Publications of  Tamás Turányi


1      A. Császár, L. Jicsinszky, T. Turányi
        Generation of model reactions leading to limit cycle behaviour
        React.Kinet.Catal.Lett., 18, 65-71(1981)
        ABSTRACT 

2      A. Császár, P. Érdi, L. Jicsinszky, T. Tóth, T. Turányi
        Several exact results on deterministic exotic kinetics
        Z. Phys. Chem. (Leipzig), 264, 449-463(1983)
        ABSTRACT 

3      S. Vajda, P. Valkó, T. Turányi
        Principal component analysis of kinetic models
        Int.J.Chem.Kinet., 17, 55-81(1985)
        ABSTRACT 

4      S. Vajda, T. Turányi
        Principal component analysis for reducing the Edelson-Field-Noyes model of the Belousov-Zhabotinsky reaction
        J.Phys.Chem., 90, 1664-1670(1986)
        ABSTRACT 

5      T. Bérces, T. Turányi, L. Haszpra
        The kinetics of reactions occuring in the unpolluted troposphere I , Formulation of reaction mechanism
        Acta Chim.Hung., 122, 147-161(1986)
        ABSTRACT 

6      L. Haszpra, T. Turányi
        Production of nitric acid in the atmosphere under different conditions
        Időjárás, 90, 332-338(1986)
        ABSTRACT 

7      T. Turányi, L. Haszpra, T. Bérces
        A photochemical air pollution model
        Proceedings of the European Congress on Simulation
        Academia , Prague , 1987 , Appendix pp 204-207
        ABSTRACT 

8      T. Turányi, T. Bérces, J. Tóth
        The method of quasi-stationary sensitivity analysis
        J.Math.Chem., 2, 401-410(1988)
        ABSTRACT 

9      L. Haszpra, I. Szilágyi, Gy. Bácskai, T. Cziczó, A. Demeter, M. Kertész, T. Turányi
        Exploratory measurements in Budapest for the detection of photochemical air pollution (in Hungarian)
        Egészségtudomány, 32, 363-374(1988)
        ABSTRACT 

10    T. Turányi, T. Bérces, S. Vajda
        Reaction rate analysis of complex kinetics systems
        Int.J.Chem.Kinet., 21, 83-99(1989)
        ABSTRACT 

11    T. Turányi, T. Bérces
        The kinetics of reactions occuring in the unpolluted troposphere, II . Sensitivity analysis
        React.Kinet.Catal.Lett., 41, 103-108(1990)
        ABSTRACT 

12    T. Turányi
        Rate sensitivity analysis of a model of the Briggs-Rauscher reaction
        React.Kinet.Catal.Lett., 45, 235-241(1991)
        ABSTRACT 

13    T. Turányi
        KINAL: A program package for kinetic analysis of complex reaction mechanisms
        Comp.Chem., 14, 253-254(1990)
        ABSTRACT 

14    T. Turányi
        Reduction of large reaction mechanisms
        New J.Chem., 14, 795-803(1990)
        ABSTRACT 

15    T. Turányi
        Sensitivity analysis of complex kinetic systems: Tools and applications
        J.Math.Chem., 5, 203-248(1990)
        ABSTRACT 

16    L. Györgyi, T. Turányi, R.J. Field
        Mechanistic details of the oscillatory Belousov-Zhabotinskii reaction
        J.Phys.Chem., 94, 7162-7170(1990)
        ABSTRACT 

17    T. Turányi, L. Györgyi, R.J. Field
        Analysis and simplification of the GTF model of the Belousov-Zhabotinsky reaction
        J.Phys.Chem, 97, 1931-1941(1993)
        ABSTRACT 

18    S. Dóbé, T. Turányi, T. Bérces, F. Márta
        The kinetics of hydroxyl radical reactions with cyclopropane and cyclobutane
        Proc.Indian Acad.Sci.(Chem.Sci.), 103, 499-503(1991)
        ABSTRACT 

19    L. Haszpra, I. Szilágyi, A. Demeter, T. Turányi, T. Bérces
        Non-methane hydrocarbon and aldehyde measurements in Budapest, Hungary
        Atm.Environm., 25A, 2103-2110(1991)
        ABSTRACT 

20    T. Bérces, T. Turányi
        Generation and distribution of ozone in the vicinity of large pollution sources (in Hungarian)
        Időjárás, 95, 110-118(1991)
        ABSTRACT 

21    A.S. Tomlin, M.J. Pilling, T. Turányi, J.H. Merkin, J. Brindley
        Mechanism reduction for the oscillatory oxidation of hydrogen sensitivity and quasi-steady state analyses
        Combust.Flame, 91, 107-130(1992)
        ABSTRACT  

22    K.J. Hughes, P.A. Halford-Maw, P.D. Lightfoot, T. Turányi, M.J. Pilling
        Direct measurements of the neopentyl peroxy-hydroperoxy radical isomerisation over the temperature range 660-750 K
        Proc.Combust.Inst, 24, 645-652(1992)
        ABSTRACT 

23    T. Turányi, A.S. Tomlin, M.J. Pilling
        On the error of the quasi-steady-state approximation
        J.Phys.Chem., 97, 163-172(1993)
        ABSTRACT 

24    S. Dóbé, T. Turányi, I. Iogansen, T. Bérces
        Rate constants of the reactions of OH radicals with cyclopropane and cyclobutane
        Int.J.Chem.Kinet., 24, 191-198(1992)
        ABSTRACT  

25    T. Turányi
        Computational investigation of the kinetics of reaction systems (in Hungarian)
        Kemiai kozlemenyek, 75, 97-110(1992)
        ABSTRACT 

26    T. Bérces, T. Turányi
        Role of chemistry in the characterization and depletion of air pollution (in Hungarian)
        Kemiai kozlemenyek, 75, 7-16(1992) 

27    T. Turányi, J. Tóth
        Comments to an article of Frank-Kamenetskii on the Quasi Steady State Approximation
        Acta Chim.Hung., 129, 903-914(1992)
        ABSTRACT  

28    I.Börger, A.Merkel, J.Lachmann, H.-J.Spangenberg, T.Turányi
        An extended kinetic model and its reduction by sensitivity analysis for the methanol/oxygen gas-phase thermolysis
        Acta Chim. Hung., 129, 855-864(1992)
        ABSTRACT  

29    T. Turányi, L. Györgyi
        Investigation of complex reaction mechanisms by sensitivity analysis
        pp. 298-320 (in Hungarian)
        in: Non-linear dynamics and exotic kinetic phenomena in
        chemical systems ( Ed. Gy. Bazsa)
        Debrecen-Budapest-Godollo, 1992

30    L. Zalotai, T. Turányi, T. Bérces, F. Márta
        Collisional energy transfer in the two channel decomposition of 1,1,2,2-tetrafluorocyclobutane and 1-methyl-2,2,3,3-tetrafluorocyclobutane I. Gas/gas collisions
        Reac.Kinet.Catal.Lett., 51, 401-408(1993)
        ABSTRACT  

31    L. Zalotai, T. Turányi, T. Bérces, F. Márta
        Collisional energy transfer in the two channel decomposition of 1,1,2,2-tetrafluorocyclobutane and 1-methyl-2,2,3,3-tetrafluorocyclobutane II. Gas/wall collisions
        Reac.Kinet.Catal.Lett., 51, 409-414(1993)
        ABSTRACT  

32    S. Dóbé, T. Bérces, I. Szilágyi, T. Turányi, F. Márta
        Kinetic investigations on oxygen-containing free radicals
        Magyar Kem.Lapja, 48, 361-368(1993) (in Hungarian)

33    T. Turányi
        Parameterization of reaction mechanisms using orthonormal polynomials
        Computers Chem., 18, 45-54(1994)
        ABSTRACT 

34    T. Turányi
        Application of repro-modelling for the reduction of combustion mechanisms
        Proc.Combust.Inst., 25, 949-955(1995)
        ABSTRACT 

35    A.S. Tomlin, T. Turányi, M.J. Pilling
        Mathematical tools for the construction, investigation and reduction of combustion mechanisms
        in: `Low temperature combustion and autoignition', eds. M.J. Pilling and G. Hancock,
        Comprehensive Chemical Kinetics, 35, 293–437(1997)
        ABSTRACT 

36    F.C. Christo, A.R. Masri, E.M. Nebot, T. Turányi
        Utilising artifical neural network and repro-modelling in turbulent combustion
        Proceedings of the IEEE International Conference
        on Neural Networks, Perth, 27th November-1st December 1995,
        Vol. 1, pp. 911-916, 1995
        ABSTRACT 

37    T. Turányi
        Applications of sensitivity analysis to combustion chemistry
        Proceedings of SAMO '95 (Theory and applications of
        sensitivity analysis of model output in computer simulation),
        25-27 September, 1995, Belgirate, Italy, pp. 33-35

38    S. Dóbé, T. Bérces, T. Turányi, F. Márta, J. Grüssdorf, F. Temps, H.Gg. Wagner
        Direct kinetic studies of the reactions Br+CH3OH and CH2OH+HBr: The heat of formation of CH2OH
        J.Phys.Chem, 100, 19864-19873(1996)
        ABSTRACT  

39    T. Turányi
        Applications of sensitivity analysis to combustion chemistry
        Reliability Engineering & System Safety, 57, 41-48(1997)
        ABSTRACT  

40    T. Turányi
        Reduction of reaction mechanisms on the basis of the repro-modelling approach
        in: Proceedings of the workshop on 'Numerical aspects of reduction in chemical kinetics'
        2nd September, 1997, CERMICS, Paris  

41    L.J. Clifford, A.M. Milne, T. Turányi, D. Boulton
        An induction parameter model for shock-induced hydrogen combustion simulations
        Combustion and Flame, 113, 106-118(1998)
        ABSTRACT  

42    T. Turányi, H. Rabitz
        Local methods
        pp. 81-99, in: 'Sensitivity analysis'
        eds: A. Saltelli, K. Chan, E.M. Scott
        Wiley, Chichester, 2000
        FURTHER INFO 

43    A. Obieglo, J. Gass, A. Büki, T. Turányi
        PDF-Berechnung einer turbulenten Flamme unter Verwendung des Repromodellierens
        VDI Berichte, 1492, 487-492(1999)
        ABSTRACT 

44    T. Turányi
        A reakciókinetika néhány újabb eredménye a légkörkémiában és az égéstudományban
        (Some new results of reaction kinetics in atmospheric and combustion chemistry)
        Magy. Kém. Folyóirat, 55, 323-326(2000)
        ABSTRACT 
        

45    K.J. Hughes, T. Turányi, A. Clague, M.J.Pilling
        Development and testing of a comprehensive chemical mechanism for the oxidation of methane
        Int.J.Chem.Kinet., 33, 513-538(2001)
        ABSTRACT          

46    K.J. Hughes, A.S. Tomlin, E. Hampartsoumian, W. Nimmo, I.G. Zsély, M.Ujvári,
        T. Turányi, A.R. Clague, M.J. Pilling
        An Investigation of Important Gas Phase Reactions of Nitrogen Species from the
        Simulation of Bulk Experimental Data in Combustion Systems
        Combust.Flame, 124, 573-589(2001)
        ABSTRACT 

47    T. Turányi, T. Perger and L. Balázs
        Reaction-diffusion modelling of cylindrical halogen lamps
        in: High Temperature Materials Chemistry
        Proceedings of the 10th International IUPAC Conference
        held from 10 to 14 April 2000 at the Forschungszentrum Jülich, Germany
        Editors: K. Hilpert, F.W. Froben and L. Singheiser
        Schriften des Forschungszentrum Jülich, Vol. 15, Part I, pp. 321-324, 2000
        ABSTRACT 

48    I. Lagzi, A.S. Tomlin, T. Turányi, L. Haszpra, R. Mészáros, M. Berzins
        Modelling Photochemical Air Pollution in Hungary Using an Adaptive Grid Model
        pp. 264-273   in:'Air Pollution Modelling and Simulation', editor: B. Sportisse,
        Springer, Berlin, 2002, ISBN 3-540-42515-2
        ABSTRACT 

49    I. Lagzi, A.S. Tomlin, T. Turányi, L. Haszpra, R. Mészáros, M. Berzins
        The Simulation of Photochemical Smog Episodes in Hungary and Central Europe Using Adaptive Gridding Models.
        Lecture Notes in Computer Science, 2074, 67-76(2001)
        ABSTRACT 

50    I.Gy. Zsély, T. Turányi
        Investigation and reduction of two methane combustion mechanisms
        Archivum Combustionis, 21, 173-177(2001)
        ABSTRACT 

51    T. Turányi, L. Zalotai, S. Dóbé, T. Bérces
        Effect of the uncertainty of kinetic and thermodynamic data on methane flame simulation results
        Phys.Chem.Chem.Phys., 4, 2568-2578(2002)
        ABSTRACT 
        FULL TEXT 

52    A. Büki, T. Perger, T. Turányi, U. Maas
        Repro-modelling Based Generation of Intrinsic Low-dimensional Manifolds
        J.Math.Chem., 31, 345-362(2002)
        ABSTRACT 

53    I. Lagzi, A.S. Tomlin, T. Turányi, L. Haszpra, R. Mészáros, M. Berzins
        Modelling Tropospheric Ozone Formation in Hungary using an Adaptive Gridding Method
        Proceedings from the EUROTRAC-2 Symposium 2002, P.M. Midgley, M. Reuters (Eds.),
        Margraf Verlag, Weikersheim, 2002
        ABSTRACT 

54    T. Perger, T. Kovács, T. Turányi, C. Trevińo
        Determination of adsorption and desorption parameters from ignition temperature measurements
        in catalytic combustion systems
        J.Phys.Chem. B, 107, 2262-2274(2003)
        ABSTRACT 

55    I. Gy. Zsély, J. Zádor, T. Turányi
        Similarity of sensitivity functions of reaction kinetic models
         J.Phys.Chem. A, 107, 2216-2238 (2003)
        ABSTRACT 

56    L. Haszpra, I. Lagzi, T. Turányi, A.S.Tomlin, G. Radnóti
        Nyári szmog-helyzetek előrejelzése adaptív rácsmodellel
        (Forecast of summer smog episodes using an adaptive grid model, in Hungarian)
        Proceedings of 'Meteorológiai Tudományos Napok 2002'
        pp. 119-123 and Table IX in: , A meteorológiai előrejelzések és alkalmazásaik
        (Forecast in meteorology and its applications), ed: J. Mika,
        Országos Meteorológiai Szolgálat, Budapest, 2002, ISBN 963 7702 86 5
        ABSTRACT 

57    I. Lagzi, T. Turányi, A.S. Tomlin, L. Haszpra.
        Simulation of the effect of the plume of Budapest on the photochemical air pollutants formation in Hungary
        pp. 55-57 in: Proceedings of the 4th International Conference on Urban Air Quality
        23-27 March, 2003, Prague, R.S. Sokhi and J. Brechler (eds.)
        ABSTRACT 

58    I. Gy. Zsély, J. Zádor and T. Turányi
        Local and global similarity of sensitivity vectors of combustion kinetic models
        pp. 849-859 in: Proceedings of the 3rd Mediterranean Combustion Symposium,
        Marrakech, Morocco, June 8-13, 2003
        Editors: F. Beretta and A. Bouhafid
        ABSTRACT 

59    T. Perger, T. Kovács, T. Turányi, C. Trevińo
        Determination of adsorption and desorption parameters from heterogeneous ignition temperature measurements
        pp. 860-870 in: Proceedings of the 3rd Mediterranean Combustion Symposium,
        Marrakech, Morocco, June 8-13, 2003
        Editors: F. Beretta and A. Bouhafid
        ABSTRACT 

60    I. Lagzi, T. Nagy, T. Turányi, L. Haszpra, A.S. Tomlin
        Simulation of the formation and spread of photochemical air pollution in Hungary
        pp. 495-500 in: Proceedings of the Conference on Modelling Fluid Flow (CMFF'03)
        Budapest, Hungary, September 3 - 6, 2003
        ABSTRACT 

61    Kovács T., Turányi T.
        Modelling of the decomposition of CCl4 in thermal plasma
        in: Proceedings of the 2nd International Meeting on Chemistry,
        3-6 June, 2003, Santa Clara, Cuba
        ISBN 959-250-080-0
        ABSTRACT 

62    R. Deters, H. Gg. Wagner, Á. Bencsura, K. Imrik, S. Dóbé, T. Bérces, F. Márta, F. Temps, T. Turányi, I. Gy. Zsély
        Direct kinetic determination of rate parameters for the reaction CH3 + OH. Implications for methane flame modelling
        Proceedings of the European Combustion Meeting 2003, Paper No. 21
        ABSTRACT 

63    I. Gy. Zsély, J. Zádor, T. Turányi
        Uncertainty analysis backed development of combustion mechanisms
        Proceedings of the European Combustion Meeting 2003, Paper No. 35
        ABSTRACT 

64    I. Gy. Zsély, T. Turányi
        The influence of thermal coupling and diffusion on the importance of reactions:
        The case study of hydrogen-air combustion
        Phys.Chem.Chem.Phys., 5, 3622-3631(2003)
        ABSTRACT 

65    I. Lagzi, D. Kármán, T. Turányi, A.S. Tomlin, L. Haszpra
        Simulation of the dispersion of nuclear contamination using an adaptive Eulerian grid model
        J. Environm. Radioact., 75, 59-82(2004)
        ABSTRACT 

66   J. Zádor, I. Gy. Zsély, T. Turányi
        Investigation of the correlation of sensitivity vectors of hydrogen combustion models
        Int.J.Chem.Kinet., 36, 238-252(2004)
        ABSTRACT 

67    R. Lovas, P. Kacsuk, I. Lagzi, T. Turányi
        Unified development solution for cluster and grid computing and its application in chemistry
        Lecture Notes Comp. Sci., 3044, 226-235(2004)
        ABSTRACT 

68     T. Turányi, I. Gy. Zsély, and J. Zádor
        Selforganization in high temperature reaction kinetic systems
        pp. 134-137, in: Proceedings of the conference "Selforganization in nonequilibrium systems" 
        Slobodan Anic, Zeljko Cupic, Ljiljana Kolar-Anic (eds.)
        (Belgrade, September 24-25, 2004), ISBN: 86-82475-15-4
        ABSTRACT 

69     I. Gy. Zsély, J. Zádor, T. Turányi
        Uncertainty analysis of updated hydrogen and carbon monoxide oxidation mechanisms
        Proc. Combust. Inst., 30, 1273-1281(2005)
        ABSTRACT 

70     I. Lagzi, R. Mészáros, L. Horváth, A.S. Tomlin, T. Weidinger, T. Turányi, F. Ács, L. Haszpra
        Modelling ozone fluxes over Hungary
        Atm. Environm., 38, 6211-6222 (2004)
        ABSTRACT 

71   J. Zádor, I. Gy. Zsély, T. Turányi
        Local and global uncertainty analysis of complex chemical kinetic systems
        Rel. Engng. Syst. Safety, 91, 1232–1240 (2006)
        ABSTRACT 

72    I. Lagzi, R. Lovas, T. Turányi
        Development of a Grid enabled chemistry application
        in: Distributed and Parallel Systems: Cluster and Grid Computing, Z. Juhasz; P. Kacsuk; D. Kranzlmuller (Eds.)
        The Kluwer International Series in Engineering and Computer Science,
        777, 137-144(2004), ISBN: 0-387-23094-7
        ABSTRACT 

73    T. Kovács, T. Turányi, K. Föglein, J. Szépvölgyi
        Kinetic modelling of the decomposition of carbon tetrachloride in thermal plasma
        Plasma Chemistry and Plasma Processing, 25, 109-119(2005)
        ABSTRACT 

74    T. Perger, T. Kovács, T. Turányi, C. Trevińo
        Determination of the adsorption and desorption parameters for ethene and propene
        from measurements of the heterogenous ignition temperature
        Combustion and Flame, 142, 107-116(2005)
        ABSTRACT 

75    I. Gy. Zsély, J. Zádor, T. Turányi
        On the similarity of the sensitivity functions of methane combustion models
        Combustion Theory and Modelling, 9, 721-738(2005)
        ABSTRACT 

76    J. Zádor, I. Gy. Zsély, T. Turányi, M. Ratto, S. Tarantola, A. Saltelli
        Local and global uncertainty analyses of a methane flame model
        J. Phys. Chem. A, 109, 9795-9807(2005)
        ABSTRACT 

77    I. Gy. Zsély, I. Virág, T. Turányi
        Investigation of a methane oxidation mechanism via the visualization of element fluxes
        Paper IX.4 in: Proceedings of the 4th Mediterranean Combustion Symposium,
        Lisbon, Portugal, 5-10 October, 2005
        Editors: F. Beretta, N. Selçuk, M.S. Mansour
        ABSTRACT 

78    T. Kovács, T. Turányi, K. Föglein, J. Szépvölgyi
        Modelling of Carbon Tetrachloride Decomposition in Oxidative RF Thermal Plasma
        Plasma Chemistry and Plasma Processing, 26, 293-318(2006)
        ABSTRACT 

79    I. Lagzi, A. S. Tomlin, T. Turányi, L. Haszpra
        Photochemical air pollutant formation in Hungary using an adaptive gridding technique
        Int.J. Environment and Pollution, 36, 44-58(2009)
        ABSTRACT 

80    R. Mészáros, D. Szinyei, Cs. Vincze, I. Lagzi, T. Turányi, L. Haszpra, A. S. Tomlin
        Effect of the soil wetness state on the stomatal ozone fluxes over Hungary
        Int.J. Environment and Pollution36, 180-194(2009)
        ABSTRACT 
   
81    J. Zádor, T. Turányi,  K. Wirtz, M. J. Pilling
        Measurement and investigation of chamber radical sources in the European Photoreactor (EUPHORE)        
        J. Atmos. Chem., 55, 147-166(2006)
        ABSTRACT 

82    R. Lovas, J. Patvarczki, P. Kacsuk, I. Lagzi, T. Turányi, L. Kullmann, L. Haszpra, R. Mészaros, A. Horányi, A. Bencsura, Gy.Lendvay:
        Air pollution forecast on the HUNGRID infrastructure
        Gerhard R. Joubert, Wolfgang E. Nagel, Frans J. Peters, Oscar G. Plata, P. Tirado, Emilio L. Zapata (Eds.), ISBN 3-00-017352-8
        Parallel Computing: Current & Future Issues of High-End Computing, John von Neumann Institute for Computing, Julich, Germany 2005,
        NIC Series, 33, 121-128 (2006)
        ABSTRACT 

83     T. Kovács, I. Gy. Zsély, Á. Kramarics, T. Turányi 
         Kinetic analysis of mechanisms of complex pyrolytic reactions
         J. Anal. Appl. Pyrolysis, 79, 252-258(2007)
         
ABSTRACT

84    A. Lovrics, A. Csikász-Nagy, I. Gy. Zsély, J. Zádor, T. Turányi, B Novák
        Time scale and dimension analysis of a budding yeast cell cycle model
        BMC Bioinformatics, 7:494(2006)
         
ABSTRACT

85    I. Lagzi, R Mészáros, F Ács, A S Tomlin, L Haszpra, T Turányi
        Description and evaluation of a coupled Eulerian transport-exchange model: Part I. Model development
        Idöjárás, 110, 349-363 (2006)
        ABSTRACT

86    Á. Kramarics, I. Gy. Zsély, T. Turányi
        Analysis of a methane partial oxidation mechanism relevant
at the conditions of the anode channels of a solid-oxide fuel cell
        Proceedings of the European Combustion Meeting 2007, Paper 13-6
        ABSTRACT

87    T. Kovács, T. Turányi, K. Föglein, J. Szépvölgyi
        Comparison of the efficiencies and kinetic analysis of the carbon tetrachloride decomposition in RF thermal plasma in inert and oxidative environments
        Proceedings of the 18th International Symposium on Plasma Chemistry (ISPC), Kyoto, Japan, 26-31 August, 2007
        ABSTRACT

88    T. Turányi
        Sensitivity analysis in chemical kinetics (editorial)
        Int.J.Chem.Kinet., 40, 685-686 (2008)
        ABSTRACT

89    A. Lovrics, I. Gy. Zsély, A. Csikász-Nagy, J. Zádor, T. Turányi, B. Novák
        Analysis of a budding yeast cell cycle model using the shapes of local sensitivity functions
        Int.J.Chem.Kinet., 40, 710-720 (2008)
        ABSTRACT

90    I. Gy. Zsély, J. Zádor, T. Turányi
        Uncertainty analysis of NO production during methane combustion
        Int.J.Chem.Kinet., 40, 754-768 (2008)
        ABSTRACT

91    T. Nagy, T. Turányi
        Reduction of very large reaction mechanisms using methods based on simulation error minimization
        Combustion and Flame, 156,  417–428 (2009)
        ABSTRACT
        Related computer codes are available.

92    T. Nagy, T. Turányi
        Relaxation of concentration perturbation in chemical kinetic systems
        Reaction Kinetics and Catalysis Letters96, 269−278 (2009)
        ABSTRACT

93    I. Lagzi, T. Turányi, R. Lovas
        Development of a grid enabled chemistry application
        Int. J. Computational Science and Engineering, 4, 195-203 (2009)
        ABSTRACT

94    T. Kovács, T. Turányi 
        Chemical reactions in the Titan's troposphere during lightning
        Icarus, 207, 938–947(2010)
        ABSTRACT        

95    T. Kovács, T. Turányi, J. Szépvölgyi
        CCl4 decomposition in RF thermal plasma in inert and oxidative environments
        Plasma Chemistry and Plasma Processing, 30, 281-286 (2010)
        ABSTRACT 

96    Turányi T.
        Reakciómechanizmusok vizsgálata
        Akadémiai Kiadó, Budapest, 2010
        ABSTRACT 

97    T. Nagy, T. Turányi
        Uncertainty analysis of varying temperature chemical kinetic systems
        Procedia Social and Behavioral Sciences, 2, 7757–7758 (2010)
        ABSTRACT 

98    T. Nagy, T. Turányi
         Uncertainty of Arrhenius parameters
        Int. J. Chem. Kinet., 43, 359–378(2011)
        ABSTRACT
        Related computer codes are available.

99    L. Varga, B. Szabó, I.Gy. Zsély, A. Zempléni, T. Turányi
        Numerical investigation of the uncertainty of Arrhenius parameters
         J. Math. Chem., 49, 1798-1809 (2011)
        ABSTRACT

100   T. Nagy, T. Turányi
         Determination of the uncertainty domain of the Arrhenius parameters needed for the investigation of combustion kinetic models
         Reliability Engineering and System Safety, 107, 29–34 (2012)
        Related computer codes are available.
        ABSTRACT

101   I. Sedyó, T. Nagy, I. Zsély, T. Turányi
         Uncertainty of the Arrhenius parameters of important elementary reactions of the hydrogen-oxygen system
         Proceedings of the ECM, Paper 163, 2011
         ABSTRACT

102   T. Varga, I. Zsély, T. Turányi
         Collaborative development of reaction mechanisms using PrIMe datafiles
         Proceedings of the ECM, Paper 164, 2011
         ABSTRACT

103   J. Danis, T. Turányi
         Sensitivity analysis of bacterial chemotaxis models
         Procedia Computer Science, 7,  233–234(2011)
         ABSTRACT

104   T. Turányi, T. Nagy, I. Gy. Zsély, M. Cserháti, T. Varga, B.T. Szabó, I. Sedyó, P. T. Kiss, A. Zempléni, H. J. Curran         
         
Determination of rate parameters based on both direct and indirect measurements
         Int.J.Chem.Kinet., 44, 284–302(2012)
         ABSTRACT

105   I. Gy. Zsély, T. Varga, T. Nagy, M. Cserháti, T. Turányi, S. Peukert, M. Braun-Unkhoff, C. Naumann, U. Riedel
         Determination of rate parameters of cyclohexane and 1-hexene decomposition reactions
         Energy43 , 85-93(2012)
         ABSTRACT

106   T. Turányi, Z. Tóth
         Hungarian university students’ misunderstandings in thermodynamics and chemical kinetics
         Chemistry Education Research and Practice14, 105-116(2013) 
         ABSTRACT

107   T. Turányi
         Cell Cycle Models, Sensitivity Analysis
         Encyclopedia of Systems Biology, (editors in chief: Werner Dubitzky, Olaf Wolkenhauer, Kwang-Hyun Cho, Hiroki Yokota)
         Springer, 2013
         ABSTRACT
         
108   Bazsó G., Góbi S. Magyarfalvi G., Zügner G., Demeter A., Turányi T., Dóbé S., Tarczay Gy.
         Az ELTE TTK Lézerlaboratóriuma: Első eredmények és kutatási perspektívák
         Magyar Kémiai Folyóirat118, 65-71(2012)  
         ABSTRACT

109   Turányi T, Zsély I.Gy., Nagy T, Varga T., Pálvölgyi R.
         Reakciósebességi paraméterek meghatározása közvetlen és közvetett mérések együttes felhasználásával
         Magyar Kémiai Folyóirat118, 129-136(2012)  
         ABSTRACT
 
110    I.Gy. Zsély, C. Olm, R. Pálvölgyi, T. Varga, T. Nagy, T. Turányi
          Comparison of the performance of several recent hydrogen combustion mechanisms
          Proceedings of the European Combustion Meeting 2013, Paper P4-13. ISBN 978-91-637-2151-9.
         ABSTRACT

111    C. Olm, I. Gy. Zsély, T. Varga, T. Nagy, T. Turányi
          Comparison of the performance of several recent wet CO combustion mechanisms
          Proceedings of the European Combustion Meeting 2013, Paper P5-2. ISBN 978-91-637-2151-9.
         ABSTRACT

112    T. Nagy, C. Olm, I. Gy. Zsély, T. Varga, R. Pálvölgyi, É. Valkó, G. Vincze, T. Turányi
          Optimisation of a hydrogen combustion mechanism
          Proceedings of the European Combustion Meeting 2013, Paper P4-14. ISBN 978-91-637-2151-9.
          ABSTRACT

113    A.S. Tomlin, T. Turányi 
          Investigation and improvement of reaction mechanisms using sensitivity analysis and optimization
          Chapter 16 in: Development of detailed chemical kinetic models for cleaner combustion
          editors: F. Battin-Leclerc, E. Blurock, J. Simmie, pp. 411-445
          Springer, Heidelberg, 2013
          ISBN: 978-1-4471-5306-1 (Print) 978-1-4471-5307-8 (Online)
          ABSTRACT

114    A.S. Tomlin, T. Turányi 
          Mechanism reduction to skeletal form and species lumping
          Chapter 17 in: Development of detailed chemical kinetic models for cleaner combustion
          editors: F. Battin-Leclerc, E. Blurock, J. Simmi, pp. 447-466
          Springer, Heidelberg, 2013
          ISBN: 978-1-4471-5306-1 (Print) 978-1-4471-5307-8 (Online)
          ABSTRACT

115    T. Turányi, A.S. Tomlin 
          Storage of chemical kinetic information
          Chapter 19 in: Development of detailed chemical kinetic models for cleaner combustion
          editors: F. Battin-Leclerc, E. Blurock, J. Simmie, pp. 485-512
          Springer, Heidelberg, 2013
          ISBN: 978-1-4471-5306-1 (Print) 978-1-4471-5307-8 (Online)
          ABSTRACT

116    B. Könnyű, S. K. Sadiq, T. Turányi, R. Hírmondó, B. Müller, H-G Kräusslich, P. V. Coveney, V. Müller
          Gag-Pol Processing during HIV-1 Virion Maturation: a Systems Biology Approach           
          PLoS Comput. Biol., 9(6): e1003103. doi:10.1371/journal.pcbi.1003103  (2013)
          ABSTRACT

117    Bányai István, Gáspár Vilmos, Horváthné Csajbók Éva, Kiss Éva, Nagy Noémi, Póta György, Purgel Mihály, Turányi Tamás, Viskolcz Béla:
          Modern fizikai kémia
          Debrecen-Budapest-Szeged, 2013

118   T. Varga, I. Gy. Zsély, T. Turányi, T. Bentz, M. Olzmann
         Kinetic analysis of ethyl iodide pyrolysis based on shock tube measurements
         Int.J.Chem.Kinet., 46, 295–304 (2014)
         ABSTRACT

119   C. Olm, I. Gy. Zsély, R. Pálvölgyi, T. Varga, T. Nagy, H. J. Curran, T. Turányi
         Comparison of the performance of several recent hydrogen combustion mechanisms
          Combust. Flame
161, 2219-2234 (2014)
         ABSTRACT

120   T. Varga, T. Nagy, C. Olm, I.Gy. Zsély, R. Pálvölgyi, É. Valkó, G. Vincze, M. Cserháti, H.J. Curran, T. Turányi
         Optimization of a hydrogen combustion mechanism using both direct and indirect measurements
         Proc. Combust. Inst.,  35, 589-596
(2015)
         ABSTRACT

121   T. Turányi, A. S. Tomlin
         Analysis of kinetic reaction mechanisms
         
Springer, 2014
         ABSTRACT

122   C. Olm, I. Gy. Zsély, T. Varga, H. J. Curran, T. Turányi
         Comparison of the performance of several recent syngas combustion mechanisms
         Combust. Flame,  162, 1793-1812 (2015)
          ABSTRACT

123   T. Nagy, É. Valkó, I. Sedyó, I. Gy. Zsély, M. J. Pilling, T. Turányi
         
Uncertainty of the rate parameters of several important elementary reactions of the H2 and syngas combustion systems
         Combust. Flame, 162, 2059-2076 (2015)
         ABSTRACT
 
124  Tamás Varga, Tamás Turányi, Eszter Czinki, Tibor Furtenbacher, Attila G. Császár
        ReSpecTh: a joint reaction kinetics, spectroscopy, and thermodynamics information system
        Proceedings of the European Combustion Meeting – 2015, Paper P1-04, March 30–April 2, 2015, Budapest, Hungary,
        ISBN 978-963-12-1257-0
        ABSTRACT

125  Carsten Olm, Tamás Varga, Éva Valkó, Sandra Hartl, Christian Hasse, Tamás Turányi
        Development of an ethanol combustion mechanism based on a hierarchical optimization approach
        Proceedings of the European Combustion Meeting – 2015, Paper P1-35, March 30–April 2, 2015, Budapest, Hungary,
        ISBN 978-963-12-1257-0
        ABSTRACT

126   Viktor Samu, Tamás Varga, Tamás Turányi
         Investigation of ethane pyrolysis and oxidation at high pressures using global optimization based on shock tube data
        Proceedings of the European Combustion Meeting – 2015, Paper P1-38, March 30–April 2, 2015, Budapest, Hungary,
        ISBN 978-963-12-1257-0
        ABSTRACT

127  Éva Valkó, Alison S. Tomlin, Tamás Varga, Tamás Turányi
        Investigation of the effect of correlated uncertain rate parameters on a model of hydrogen combustion using a generalized HDMR method
        Proceedings of the European Combustion Meeting – 2015, Paper P1-39, March 30–April 2, 2015, Budapest, Hungary,
        ISBN 978-963-12-1257-0
        ABSTRACT

128  Róbert Pálvölgyi, Tamás Varga, Tamás Turányi
        Investigations of available experimental and modeling data on the oxidative coupling and partial oxidation of methane
        Proceedings of the European Combustion Meeting – 2015, Paper P1-70, March 30–April 2, 2015, Budapest, Hungary,
        ISBN 978-963-12-1257-0
        ABSTRACT

129  Tamás Turányi
        Analysis of Complex Reaction Schemes
        Elsevier Reference Module in Chemistry, Molecular Sciences and Chemical Engineering, Article 11529, 2016
        doi:10.1016/B978-0-12-409547-2.11529-X
        ABSTRACT

130  T. Varga, C. Olm, T. Nagy, I. Gy. Zsély, É. Valkó, R. Pálvölgyi, H. J. Curran, T. Turányi
        Development of a joint hydrogen and syngas combustion mechanism based on an optimization approach     
         Int.J.Chem.Kinet., 48, 407–422 (2016)
         ABSTRACT

131    C. Olm, T. Varga, É. Valkó, S, Hartl, C. Hasse, T. Turányi
          Development of an ethanol combustion mechanism based on a hierarchical optimization approach
         Int.J.Chem.Kinet.48, 423–441 (2016)
         ABSTRACT

132    V. Samu, T. Varga, K. Brezinsky, T. Turányi
          Investigation of ethane pyrolysis and oxidation at high pressures using global optimization based on shock tube data
         Proc. Combust. Inst.36, 691–698 (2017)
         ABSTRACT

133    É. Valkó, T. Varga, A.S. Tomlin, T. Turányi
          Investigation of the effect of correlated uncertain rate parameters on a model of hydrogen combustion
          using a generalized HDMR methodusing a generalized HDMR method
          Proc. Combust. Inst.36, 681-689 (2017)
         ABSTRACT

134    É. Valkó, T. Varga, A.S. Tomlin, Á. Busai, T. Turányi
          Általánosított HDMR-módszer alkalmazása korrelált bizonytalan paraméterek hatásának vizsgálatára
          Alkalmazott Matematikai Lapok, 33, 139-157 (2016)
         ABSTRACT

135   Cheng Chi, Gábor Janiga, Abouelmagd Abdelsamie Katharina Zahringer, Tamás Turányi, Dominique Thévenin
         DNS study of the optimal chemical markers for heat release in syngas flames
         Flow, Turbulence and Combustion98, 1117–1132 (2017)
         DOI: 10.1007/s10494-016-9799-1
         ABSTRACT

136   Carsten Olm, Tamás Varga, Éva Valkó, Henry J. Curran, Tamás Turányi
         Uncertainty quantification of a newly optimized methanol and formaldehyde combustion mechanism
         Combust. Flame 186, 45-64 (2017)
         ABSTRACT

137   Viktor Samu; Tamás Varga; Igor Rahinov; Sergey Cheskis; Tamás Turányi
         Determination of rate parameters based on NH2 concentration profiles measured in ammonia-doped methane−air flames
         Fuel, in press (2017)
         ABSTRACT

138   É. Valkó, T. Varga, A.S. Tomlin, Á. Busai, T. Turányi
         Investigation of the effect of correlated uncertain rate parameters via the calculation of global and local sensitivity indices
         J. Math.Chem., in press (2017)
         ABSTRACT



Abstracts


1      A. Császár, L. Jicsinszky, T. Turányi
        Generation of model reactions leading to limit cycle behaviour
        React.Kinet.Catal.Lett., 18, 65-71(1981)

The system of differential equations by Feistel and Ebelig has been generalized. Some new formal kinetic reactions with two internal components, which may exhibit limit cycle behavior have been studied. Based upon the numerical integration of the deterministic models of these reactions the oscillatory character of the systems has been confirmed.


2      A. Császár, P. Érdi, L. Jicsinszky, T. Tóth, T. Turányi
        Several exact results on deterministic exotic kinetics
        Z.phys.Chemie, Leibzig, 264, 449-463(1983)

Exotic phenomena in the deterministic model of complex chemical reactions are studied on the basis of preliminarily reported results. It is shown that the absence of a special kind of autocatalysis, autoinhibition and cooperativity implies the existence of a unique, asymptotically stable, positive equilibrium point. The class of chemical reactions with gradient system as its deterministic model is delineated. A procedure is given for the construction of oscillatory reactions. A neurobiological application of one of the constructed models is shown.


3      S. Vajda, P. Valkó, T. Turányi
        Principal component analysis of kinetic models
        Int.J.Chem.Kinet., 17, 55-81(1985)

An eigenvalue-eigenvector analysis is used to extract meaningful kinetic information from linear sensitivity coefficients computed for several species of a reacting system at several time points. The main advantage of this method lies in its ability to reveal those parts of the mechanism which consist of strongly interacting reactions, an to indicate their importance within the mechanism. Results can be used to solve three general kinetic problems. Firstly, an objective condition for constructing a minimal reaction set is presented. Secondly, the uncovered dependencies among the parameters are shown to confirm or deny validity of quasi-steady-state assumptions under the considered experimental conditions. Thirdly, taking into account only sensitivities of observed species, the analysis is used to yield error estimates on unknown parameters determined from the experimental observations, and to suggest the parameters that should be kept fixes in the estimation procedure. To illustrate we chose the will-known hydrogen-bromine reaction and the kinetics of formaldehyde oxidation in the presence of CO.


4      S. Vajda, T. Turányi
        Principal component analysis for reducing the Edelson-Field-
        Noyes model of the Belousov-Zhabotinsky reaction
        J.Phys.Chem., 90, 1664-1670(1986)

Principal component analysis is a general method of extracting kinetic information from the array of sensitivity coefficients computed for several species of a reacting system. Eigenvectors corresponding to small eigenvalues indicate unimportant reactions and/or the validity of simplifying kinetic assumptions, thereby enabling one to optimally reduce the mechanism. Application of the method to the Edelson-Field-Noyes mechanism of the Belousov-Zhabotinsky reaction yields Oregonator-type simple models and clearly shows the kinetic approximations required for such reduction. The relative significance of individual reactions in the EFN mechanism is also determined over different subintervals of the period.


5      T. Bérces, T. Turányi, L. Haszpra
        The kinetics of reactions occuring in the unpolluted
        troposphere I , Formulation of reaction mechanism
        Acta Chim.Hung., 122, 147-161(1986)

A reaction mechanism called background model has been formuled which is intended to describe the photochemistry in the "unpolluted" troposphere i.e. in the relatively clean atmosphere not exposed to the direct perturbation from local emitting sources. The mechanism consist of 48 chemical reactions, including 12 photochemical steps, and 12 emission and deposition processes. Selection of the reactions included in the scheme has been based on competitive kinetic consideration using recent kinetic and photochemical parameters. The model has been applied to the computation of diurnal concentration profiles of the trace pollutants of the troposphere.


6      L. Haszpra, T. Turányi
        Production of nitric acid in the atmosphere under different conditions
        Idojaras, 90, 332-338(1986)

In the atmosphere the transformations of the nitrogen compounds are controlled by complicated non-linear interactions. Therefore, the relations between the emission, concentration and deposition can be described only by complex mathematical models. In the paper a model is presented by means of which the dependence of the concentration and the production rate of nitric acid on the chemical composition of the pollution emitted is studied. The calculations prove that there is no linear relation between the rate of the nitric acid production and nitrogen oxide concentration. The production rate and the concentration of nitric acid are influenced by the hydrocarbon emission/concentration.


7      T. Turányi, L. Haszpra, T. Bérces
        A photochemical air pollution model
        Proceedings of the European Congress on Simulation
        Academia , Prague , 1987 , Appendix pp 204-207

A photochemical air pollution model suitable for urban air quality calculations has been developed and tested under realistic conditions. The model treats pollutant transport by adopting the Langrangian approach. Detailed chemistry is contained in the model which includes emission and deposition processes taken into account as first order steps. A recent version of sensitivity analysis is used to reduce the original reaction mechanism to a favourable size.


8      T. Turányi, T. Bérces, J. Tóth
        The method of quasi-stationary sensitivity analysis
        J.Math.Chem., 2, 401-410(1988)

A new sensitivity analysis technique is developed by utilizing Tihonov's singular pertubation theory. The described sensitivity analysis method deals with algebraic equations instead of solving the system of differential equations, which is the case in conventional sensitivity analysis. In the field of chemical kinetics, the proposed technique can supply information on the importance of elementary steps in complex reaction mechanisms. As examples, high-temperature propane pyrolysis and the chemistry of the "unpolluted" troposphere are studied.


9      L. Haszpra, I. Szilágyi, Gy. Bácskai, T. Cziczó, A. Demeter, M. Kertész, T. Turányi
        Exploratory measurements in Budapest for the detection of
        photochemical air pollution (in Hungarian)
        Egeszsegtudomany, 32, 363-374(1988)

Exploratory measurements for the detection of the photochemical contamination of the air were carried out by co-workers of the Central Research Institute for Chemistry, of the Institute of Atmospheric Physics and of the National Institute of Public Health on seven work-days in Budapest, between August 17 and September 2, 1987. A measuring point was established on the flat roof of the National Institute of Public Health, where the hydrocarbon and aldehyde contamination and the total oxidant content of the air was measured and by the use of a recorder, the nitrogen oxide concentration of the air was monitored.
According to the measurements, the hydrocarbon concentration of the air is rather high (400-1800 ppbC) in the mornings and formaldehyde concentration shows disquietingly high values (10-180 ppb). The atmospheric total oxidant concentration did not exceed the acceptable level (10-120 ppb) in spite of the sunny summer weather. However, the measured high nitrogen oxide and hydrocarbon concentrations render probable that outside the towns, in the main current of the town contamination, high oxidant concentration may develop, endangering both the agricultural production and the natural vegetation.
The placement of the measuring point and the average weather conditions without extremities make probable that the measurements represent the average contamination conditions of a larger area.


10    T. Turányi, T. Bérces, S. Vajda
        Reaction rate analysis of complex kinetics systems
        Int.J.Chem.Kinet., 21, 83-99(1989)

Using the elementary sensitivity densities, a reaction rate sensitivity gradient is obtained which is the derivative of the rate of species concentration change with respect to the rate coefficient. The dimensionless (log-normalized) form of the reaction rate sensitivity gradient is the ratio of the rate of concentration change of species i due to elementary reaction j and the net rate of concentration change of species i. This result provides a mathematical basis for the use of various forms of reaction rate analyses. The method is used to analyze the mechanism of high-temperature formaldehyde oxidation and high-temperature propane pyrolysis. Ranking of the elementary reactions allowed us to reduce significantly the original mechanisms and a detailed study of the results revealed the reaction structures and the major reaction paths of the species.


11    T. Turányi, T. Bérces
        The kinetics of reactions occuring in the unpolluted
        troposphere, II . Sensitivity analysis
        React.Kinet.Catal.Lett., 41, 103-108(1990)

A reaction mechanism suggested for the description of the kinetics in the unpolluted troposphere was investigated by rate sensitivity and concentration sensitivity analyses. The study resulted in a 50-step reduced model and revealed the change of the importance of reactions during a diurnal cycle.



12    T. Turányi
        Rate sensitivity analysis of a model of the Briggs-Rauscher reaction
        React.Kinet.Catal.Lett., 45, 235-241(1991)

An updated mechanism for the Briggs-Rauscher reaction (also known as "Iodine Clock" reaction) has been investigated by the principal component analysis of the rate sensitivity matrix. The analysis revealed that five reactions of the 15-step model were redundant. The results of principal component and of rate-of-production analyses together gave an insight into the basic processes of the "Iodine Clock" reaction.



13      T. Turányi
        KINAL: A program package for kinetic analysis of complex reaction mechanisms
        Comp.Chem., 14, 253-254(1990)

A program package is provided for analysis of kinetic mechanisms on personal computers. KINAL consists of four programs called DIFF, SENS, PROC and YRED. These require similar input data and use common subroutines. DIFF solves stiff differential equations and SENS computes the local concentration sensitivity matrix. PROC generates the rate sensitivity matrix of the quasi-stationary sensitivity matrix from concentration data or uses a matrix computed by SENS and extract the kinetic information inherent in sensitivity matrices by principal component analysis. Finally, YRED provides suggestions for the elimination of species from the reaction mechanism.



14    T. Turányi
        Reduction of large reaction mechanisms
        New J.Chem., 14, 795-803(1990)

Systematic methods for mechanism reduction published so far consider each species equally important and therefore these
methods do not eliminate species from a mechanism even if they are insignificant. Two methods are given here for the
identification of species, which are necessary for the description of the concentration changes of important species. A reduced mechanism is obtained if the important reactions of important and necessary species are identified by the principal component analysis of the normed algebraic rate sensitivity matrix. As an example, the well-known low-temperature alkane pyrolysis model of Edelson and Allara, consisting of 98 reactions and 36 species, is reduced to a mechanism for propane pyrolysis which includes 38 reactions of 13 species. The deviations between the two models are in the order of half percent, while the computer time requirement for the solution of the reduced model is about one tenth compared to that of the full model.



15     T. Turányi
        Sensitivity analysis of complex kinetic systems:
        Tools and applications
        J.Mat.Chem., 5, 203-248(1990)

Sensitivty analysis investigation the effect of parameter change on the solution of mathematical models. In chemical kinetics, models are usually based on differential equations and the results are concentration-time curves, reaction rates, and various kinetic features of the reaction. This review discusses in detail the concentration sensitivity, rate sensitivity, and feature sensitivity analysis of spatially homogeneous constant-parameter reaction systems. Sensitivity analyses of distributed parameter systems and of stochastic systems are also briefly described. Special attention is paid to the interpretation of sensitivity coefficients which can provide information about the importance and interconnection of parameters and variables. Applications of sensitivity analysis to uncertainty analysis, parametric scaling, parameter estimation, experimental design, stability analysis, repro-modelling, and investigation and reduction of complex reaction mechanisms are discussed profoundly.



16     L. Györgyi, T. Turányi, R.J. Field
        Mechanistic details of the oscillatory Belousov-Zhabotinskii reaction
        J.Phys.Chem., 94, 7162-7170(1990)

The reactions constituting the mechanism of the oscillatory Belousov-Zhabotinskii (BZ) reaction may be divided into an inorganic and an organic subset. The former is well established and generally accepted, but the latter remains under development. There has been considerable work on component reactions of the organic subset over the past few years, but little effort has been made to incorporate the results of this work into an improved BZ mechanism. We do so and present a BZ mechanism containing 80 elementary reactions and 26 variable species concentrations and which implements recent experimental results and suggestions concerning the complicated organic chemistry, involved. The possible role of organic radicals as a second control intermediate is explored. The rate constants of the inorganic subset also are adjusted for acidity effect. The performance of the model in simulating either quantitatively of semiquantitatively a number of recent BZ experiments is substantially better than that of pervious models. Several areas in need of further work are identified.



17    T. Turányi, L. Györgyi, R.J. Field
        Analysis and simplification of the GTF model of the Belousov-Zhabotinsky reaction
        J.Phys.Chem, 97, 1931-1941(1993)

An 80-reaction, 26-species mechanistic model of the oscillatory Belousov-Zhabotinsky (BZ) reaction recently introduced by Gyorgyi, Turányi and Field (GTF model) is analyzed in this work. Major reaction interactions within the large mechanism are revealed, and by reaction rate sensitivity analysis redundant species and reactions are identified. Removal of these results in a 42-reaction, 22-species mechanism that quantitatively agrees with the original model in three test simulations. This mechanism was further simplified to 3-variable (HBrO2, Br-, Ce(IV)) skeleton models that are oscillatory under the conditions where the transient oscillations appear in the batch simulations. Two such models are put forward that oscillate without any change in the original parameter values. These skeleton models are contrasted with the Oregonator model and proved to be better description of the experimental system. It is of particular interest that these simple models do not contain any adjustable parameters. The 42-reaction mechanism is suggested as a starting point for further modeling studies with the BZ reaction. This model still contains both negative feedbacks suggested for this system, the bromide-control and the organic radical control. In the skeletons only the inhibition by bromide ions is necessary for the oscillations to occur. The simplification process reveals that the radical transfer process between malonyl radical and bromomalonic acid is of great importance in this mechanism. Recent experimental study by Forsterling and Stuk finds this reaction to be unimportant in the BZ chemistry. We propose the addition of the hydrolysis of bromomalonyl radical to the GTF model to deal with the problem and with that provide an alternative interpretation for the above experiments.



18      S. Dóbé, T. Turányi, T. Bérces, F. Márta
        The kinetics of hydroxyl radical reactions with cyclopropane and cyclobutane
        Proc.Indian Acad.Sci.(Chem.Sci.), 103, 499-503(1991)

A laser flash photolysis/resonance fluorescence investigation has been carried out to study the kinetics of the overall
reactions OH + cyclopropane (1) and OH + cyclobutane (2) in the temperature range 298-490 K and at 298 K, respectively. The following kinetic parameters have been determined: k1 = (3.9 +/- 0.6)10(-12) exp {-(2.2 +/- 0.1)kcal mol-1/RT} molecule-1 cm3 s-1, k2(298 K) = (17.5 +/- 1.5)10(-13) molecule-1 cm3 s-1.



19    L. Haszpra, I. Szilágyi, A. Demeter, T. Turányi, T. Bérces
        Non-methane hydrocarbon and aldehyde measurements in Budapest, Hungary
        Atm.Environm., 25A, 2103-2110(1991)

During three summer measuring campaigns the atmospheric concentration of non-methane hydrocarbons and aldehydes were measured at two sites in Budapest. Two hundred and forty-five flask samples were analyzed for non-methane hydrocarbon concentration and hydrocarbon composition. For formaldehyde and acetaldehyde concentration 185 and 122 samples were analyzed, respectively. The total non-methane hydrocarbon concentration shows a characteristic diurnal variation with a peak between 6 a.m. and 9 a.m. At the two sites the average concentrations between 6 a.m. and 9 a.m. are 802 and 606 ppbC, respectively. Comparing the speciation of hydrocarbons in the air of Budapest with that measured in other cities we have realized a relative surplus in C6 alkanes which is balanced by the low contribution of C3-C4 alkanes. Both the formaldehyde and acetaldehyde concentration were found rather high. In the downtown the average concentrations are 10.4 and 4.4 ppb, while 3 km away from the center of the city the corresponding values are 28.0 and 5.8 ppb.



20    T. Bérces, T. Turányi
        Generation and distribution of ozone in the vicinity of
        large pollution sources (in Hungarian)
        Idojaras, 95, 110-118(1991)

Tropospheric ozone has two origins: (i) transport from the stratosphere and (ii) O3 is a product of the NOx catalized photooxidation of airbone organic compounds. The concentration and the spatial and temporal distribution of ozone is determined by the intensity of the emission of primary pollutants, by the composition of emitted gases and by meteorological factors. Results of measurements and of model calculations for Budapest and for the surrounding areas are presented. The model calculations show that the rural areas near Budapest are highly polluted by ozone. Results of model calculations also indicate that the level of pollution expected in the future to improve significantly with the decrease of the number of vehicles equipped with two-stroke engines.



21    A.S. Tomlin, M.J. Pilling, T. Turányi, J.H. Merkin, J. Brindley
        Mechanism reduction for the oscillatory oxidation of hydrogen:
        sensitivity and quasi-steady state analyses
        Combust.Flame, 91, 107-130(1992)

A strategy for reducing complex chemical reaction mechanisms is developed and illustrated with reference to the oscillatory H2 + O2 system in a CSTR in the region of the second explosion limit. The approach involves the identification of redundant
species via rate sensitivity analysis and of redundant reactions by the principal component analysis of the rate sensitivity matrix. Temperature sensitivity analysis is also employed and the application of the quasi-steady-state approximation is discussed briefly and used in the final stages of the reduction. The above procedures are shown to assist the understanding of the underlying mechanisms of the reaction for the chosen conditions and the competition between branching steps during oscillatory ignitions is discussed. The reduced mechanism is compared with models discussed elsewhere.



22    K.J. Hughes, P.A. Halford-Maw, P.D. Lightfoot, T. Turányi, M.J. Pilling
        Direct measurements of the neopentyl peroxy-hydroperoxy
        radical isomerisation over the temperature range 660-750 K
        Proc.Combust.Inst., 24, 645-652, 1992

The rate constant for the isomerisation reaction neo-C5H11O2 => C5H10OOH (k3) has been determined directly over the temperature range 660-750 K. neo-C5H11I was photolysed at 248 nm using a KrF laser in the presence of O2 and He. The alkyl radical generated in the photolysis reacts with O2 to form the peroxy radical which then isomeries to the hydroperoxy radical. Subsequent raped reactions lead to the generation of OH, which was detected by laser induced fluorescence as a function of time. At high [O2] the time constant, lambda+, for the build up of OH tends to -k3. As [O2] decreases, earlier reactions in the peroxy radical chain become important and analysis of the [O2] dependence of lambda+, allows both k3 and k2, the rate constant for the peroxy radical decomposition, to be determined. Data analysis shows that the results are fully compatible with the steady-state measurements of Baldwin et al except that values for k3 a factor of over ten lower that their values are obtained. The discrepancy is shown to due to errors in the equilibrium constant, K2, they used for the (R2) reaction.

C2H11 + O2 <=> C5H11O2
An Arrhenius analysis gives
(k3/s-1)=10**(12.2+-0.77) exp{-(1.48+-0.12)x10**4 K/T}
The measurements of k-2 were combined with literature data for k2 and calculated values of S to give delta_H(298K)=142+-6 kJ/mol for the neo-C5H11 + O2 <=> C5H11O2 equilibrium, in satisfactory agreement with group additivity values.

23    T. Turányi, A.S. Tomlin, M.J. Pilling
        On the error of the quasi-steady-state approximation
        J.Phys.Chem., 97, 163-172(1993)

Application of the quasi-steady-state approximation (QSSA) in chemical kinetics allows the concentration of some species
(QSSA species) to be calculated not only via the solution of kinetic differential equations but also from the concentration
of other species using algebraic equations. The difference in the concentrations of QSSA species obtained from the two
calculations, at a single time point, is called the instantaneous QSSA error. This error represents a continuous perturbation of the calculated trajectory and causes an overall error in the concentrations of non-QSSA species as well. Two equations are given for the calculation of the instantaneous error. Initial selection of QSSA species can be based on the first equation, which predicts the instantaneous error of a single species. The second more involved error equation takes into account the interaction of errors of selected species and gives the instantaneous error for a group of QSSA species. Successful application of the QSSA requires that the overall error of important species be small. In some cases a small instantaneous error in the QSSA species can be magnified and results in large overall error. Such ''pathological'' cases can be detected by the calculation of the initial concentration sensitivity matrix. Those species, which induce large overall error, have to be excluded from the group of the QSSA species. The relation of the QSSA to the lifetime of species and to the stiffness of ODEs is also discussed. The use of the error formulas is illustrated by the application of the QSSA for a propane pyrolysis mechanism and briefly for the combustion of H2.



24    S. Dóbé, T. Turányi, I. Iogansen, T. Bérces
        Rate constants of the reactions of OH radicals with cyclopropane and cyclobutane
        Int.J.Chem.Kinet., 24, 191-198(1992)

The kinetics of the reactions of hydroxy radicals with cyclopropane and cyclobutane has been investigated in the
temperature range of 298-492 K with laser flash photolysis/resonance fluorescence technique. The temperature dependence of the rate constants is given by k1 = (1-17 +/- 0.15) x 10(-16) T3/2 exp[-(1037 +/- 87) kcal mol-1/RT] cm3 molecule-1 s1 and k2 = (5.06 +/- 0.57) x 10(-16) T 3/2 exp[-(228 +/- 78) kcal mol-1/RT] cm3 molecule-1 s-1 for the reactions OH + cyclopropane --> products (1) and OH + cyclobutane --> products (2), respectively. Kinetic data available for OH + cycloalkane reactions were analyzed in terms of structure-reactivity correlations involving kinetic and energetic parameters.



25    T. Turányi
        Computational investigation of the kinetics of reaction systems (in Hungarian)
        Kemiai kozlemenyek,75, 97-110(1992)

Nowadays, the application of models comprising several hundred of several thousand chemical reactions became wide-spread in chemical kinetics especially for the description of combustion and atmospheric chemical processes. Application of partial differential coefficients, derived from the kinetic differential equation, is discussed for the identification of important reactions and rate limiting steps and or the new generalize interpretation of chein length and life time of species. Based on a new interpretation of the quasi-steady-state approximation (QSSA), equations were derived for the accurate estimation of the error of QSSA.



26    T. Bérces, T. Turányi
        Role of chemistry in the characterization and depletion of air pollution (in Hungarian)
        Kemiai kozlemenyek, 75, 7-16(1992)

27    T. Turányi, J. Tóth
        Comments to an article of Frank-Kamenetskii on the Quasi Steady State Approximation
        Acta Chim.Hung., 129, 903-914(1992)

Due to the growing need for the simulation of distributed parameter systems, the method of quasi-steady-state approximation (QSSA) has been revitalized. The wide-spread use of the QSSA is hindered because of the lack of a general condition for the application of the QSSA for kinetic systems of arbitrary size. An early article of Frank-Kamenetskii gave such a condition but this work remained almost completely unknown. This paper is commented here in the light of recent results of chemical kinetics and of the theory of differential equations. The English translation of the complete original paper (Frank-Kamenetskii,D.A., Zh.Fiz.Him., 14, 695(1940) ) is also presented.



28    I.Börger, A.Merkel, J.Lachmann, H.-J.Spangenberg, T.Turányi
        An extended kinetic model and its reduction by sensitivity
        analysis for the methanol/oxygen gas-phase thermolysis
        Acta Chim. Hung., 129, 855-864(1992)

Thermolysis of methanol in the presence of oxygen was investigated by computational modelling and sensitivity
analysis in the temperature interval 900 K less-than-or-equal-to T less-than-or-equal-to 1100 K and at reaction times 10(-5) s <= t <= 1 s. Based on earlier experimental investigations and new kinetic data, a complex mechanism was set up to clarify the formation of formaldehyde, glycol, carbon monoxide, water, acetaldehyde, and formic acid, and the role of the radicals CH2OH, CH3, CHO, C2H3O, H, and O in the kinetic process. The resulting mechanism of 48 reactions and 20 species was reduced to 32 reactions and 17 species at 900 K and to 31 reactions and 17 species at 1000 K and at 1100 K. The results of simulations were compared to the experimentally measured concentrations of the pyrolytic products.


29    T. Turányi, L. Györgyi
        Investigation of complex reaction mechanisms by sensitivity analysis
        pp. 298-320 (in Hungarian)
        in: Non-linear dynamics and exotic kinetic phenomena in
        chemical systems ( Ed. Gy. Bazsa)
        Debrecen-Budapest-Godollo, 1992



30    L. Zalotai, T. Turányi, T. Bérces, F. Márta
        Collisional energy transfer in the two channel decomposition
        of 1,1,2,2-tetrafluorocyclobutane and 1-methyl-2,2,3,3-tetrafluorocyclobutane
        I. Gas/gas collisions
        Reac.Kinet.Catal.Lett., 51, 401-408(1993)

The two-channel thermal decomposition of 1,1,2,2-tetrafluorocyclobutane (TFCB) and 1-methyl-2,2,3,3-
tetrafluorocyclobutane (MTFCB) have been studied in the temperature range of 730-805 K at pressures varied from 1.1 Pa
up to 4.6 kPa. In the pressure independent range, Arrhenius expressions were obtained for TFCB decomposition into 2 CH2CF2 (k1) and C2H4 + C2F4 (k2), respectively. The same kinetic equations were determined for the decomposition of MTFCB into C3H4F2 + C2H2F2(k3) and C3H6 + C2F4 (k4). From the study of the pressure dependence of the homogeneous decomposition rates, the average downward energy transfer values of 1800 +/- 200 cm-1 and 1600 +/- 200 m-1 were obtained for the TFCB and MTFCB molecules, respectively.



31    L. Zalotai, T. Turányi, T. Bérces, F. Márta
        Collisional energy transfer in the two channel decomposition
        of 1,1,2,2-tetrafluorocyclobutane and 1-methyl-2,2,3,3-tetrafluorocyclobutane
        II. Gas/wall collisions
        Reac.Kinet.Catal.Lett., 51, 409-414(1993)

The efficiency of gas/wall vibrational energy transfer has been studied over the temperature range 800-1100 K by the ''variable encounter'' method. The average energies transferred per deactiviting collisions with the wall were determined at 800 K to be 3200 cm-1 and 2900 cm-1 for the 1,1,2,2-tetrafluorocyclobutane (TFCB) and 1-methyl-2,2,3,3-tetrafluorocyclobutane (MTFCB) molecules, respectively. This energy increased strongly with decreasing temperature. A comparison is made of [DELTAE'] with previous results for related molecules.



32    S. Dóbé, T. Bérces, I. Szilágyi, T. Turányi, F. Márta
        Kinetic investigations on oxygen-containing free radicals
        Magyar Kem.Lapja, 48, 361-368(1993) (in Hungarian)

33    T. Turányi
        Parameterization of reaction mechanisms using orthonormal polynomials
        Computers Chem., 18, 45-54(1994)

Recent methods for mechanism reduction convert large detailed chemical reaction mechanisms into small systems of differential or differential-algebraic equations. A possible further step is the parameterization of reaction mechanisms, i.e. the description of chemical kinetics by explicit functions. obtained by numerical fitting to the numerical solution of differential equations A new parameterization procedure, based on orthonormal polynomials, is described which is well applicable for fitting high-order polynomials having few effective parameters. A program is provided for the generation of multivariate Horner equations. The method is illustrated by the parameterization of a recent version of the Oregonator, a skeleton model of the oscillating Belousov Zhabotinsky reaction.



34    T. Turányi
        Application of repro-modelling for the reduction of combustion mechanisms
        Proc.Combust.Inst., 25, 948-955(1995)

The basic problem of mechanism reduction methods is to find functional relationships between selected state variables (e.g., some concentrations and temperature) and their rates. However, this information is present during the simulations with the full chemical model.
As a new applications of the repro-modeling approach, information for rates is extracted from detailed chemical calculations and stored in the form of high-order multivariate polynomials. For an efficient utilization of the polynomials, a computer program was written that rearranges them to the form of multivariate Horner equations. The repro-modeling method is an alternative to the application of the quasi-steady-state approximation (QSSA) and of the low-dimensional manifold method. Pros and cons of these three methods are discussed in detail considering the preparations required, the accuracy attainable, the yield in computer time, and the limitations of the techniques.
Simulations of the combustion of wet CO using two-variable and three-variable repro-models were 24,000 and 11,700 times faster, respectively, than the SENKIN calculation using the full model. These calculations represent the first use of repro-modeling for combustion mechanism reduction.



35    A.S. Tomlin, T. Turányi, M.J. Pilling
        Mathematical tools for the construction, investigation and reduction of combustion mechanisms
        in: `Low temperature combustion and autoignition', eds. M.J. Pilling and G. Hancock,
        Comprehensive Chemical Kinetics, 35, 293–437(1997)
        ABSTRACT 

Chemical mechanisms have been employed in hydrocarbon combustion as a means of understanding the underlying phenomenology of the combustion process in terms of the elementary reactions of individual species. This chapter provides an introduction to most of the mathematical methods that have been used for the construction, investigation, and reduction of combustion mechanisms. The use of algebraic manipulation in techniques, such as the quasi-steady-state approximation (QSSA) and lumping, make the production of a reduced mechanism essential and make subsequent calculations as simple as possible. Computational singular perturbation (CSP) is an alternative to the rate-of-production and sensitivity methods for mechanism reduction and provides an automatic selection of the important reactions as well as time-scale analysis. The simplest and most widely used technique involving the separation of time scales is the QSSA; however, a possible limitation is that it may not provide the minimum low-order system. Chemical lumping can prove very useful in areas, such as the combustion of hydrocarbon mixtures or soot formation. Several programs are available for the investigation and reduction of combustion mechanisms, including MECHMOD, a code for the automatic modification of CHEMKIN format combustion mechanisms, and KINALC, which is an almost automatic program for the investigation and reduction of gas-phase reaction mechanisms. KINALC is a postprocessor to CHEMKIN-based simulation packages SENKIN, PREMIX, OPPDIF, RUN1DL, PSR, SHOCK and EQLIB. Because models in combustion are expected to cover a wide range of conditions, it is natural to expect that a different approach might be used for different cases.



36    F.C. Christo, A.R. Masri, E.M. Nebot, T. Turányi
        Utilising artifical neural network and repro-modelling in turbulent combustion
        Proceedings of the IEEE International Conference
        on Neural Networks, Perth, 27th November-1st December 1995,
        Vol. 1, pp. 911-916, 1995

Two techniques, Artificial Neural Network (ANN) and Repro-Modelling (RM), are successfully used to represent the chemistry in turbulent combustion simulations. This is a novel application of both methods which show satisfactory accuracy in representing the chemical source term, and good ability in capturing the general behaviour of chemical reactions. The ANN model, however exhibits better generalisation feature over those of the RM approach. In terms of computational performance, the memory demand for handling the chemistry term is practically negligible for both methods. The total Central Processing Unit (CPU) time for Monte Carlo simulation of turbulent jet diffusion flame, which is dictated mainly by the time required to resolve the chemical reactions, is smaller if the RM method is used to represent the chemistry, in comparison to the time required by the ANN model. The potential and capabilities of these techniques are extendable to handle the chemistry of different fuels, and more complex chemical mechanisms.



37    T. Turányi
        Applications of sensitivity analysis to combustion chemistry
        Proceedings of SAMO '95 (Theory and applications of
        sensitivity analysis of model output in computer simulation),
        25-27 September, 1995, Belgirate, Italy, pp. 33-35

38    S. Dóbé, T. Bérces, T. Turányi, F. Márta, J. Grüssdorf, F. Temps, H.Gg. Wagner
        Direct kinetic studies of the reactions Br+CH3OH and CH2OH+HBr:
        The heat of formation of CH2OH
        J.Phys.Chem., 100, 19864-19873(1996)

The chemical equilibrium Br + CH3OH reversible arrow HBr + CH2OH (1, -1) has been studied by investigating the kinetics of the forward and reverse reactions. Excimer laser photolysis coupled with Br atom resonance fluorescence detection was used over the temperature range 439-713 K to obtain k(1) = (3.41 +/-0.89) x 10(9)T(1.5) exp[-(29.93 +/- 1.47) kJ mol(-1)/RT] cm(3) mol(-1) s(-1). The reverse reaction was studied with the fast flow technique, in the temperature range 220-473 K, using laser magnetic resonance for monitoring the CH2OH radicals. Thus, k(-1) = (1.20 +/- 0.25) x 10(12) exp[(3.24 +/- 0.44) kJ mol(-1)/RT] was obtained. The kinetic results were compared with available literature data and possible causes of the deviations were discussed. Kinetic information on the foward and back reactions was combined to obtain the heat of formation for CH2OH. Both second-law and third-law procedures were used in the derivations, giving a recommended value of Delta(f)H degrees(298)(CH2OH) = -16.6 +/- 1.3 kJ mol(-1), which corresponds to the C-H bond dissociation energy of DH degrees(298)(H-CH2OH) = 402.3 +/- 1.3 kJ mol(-1). These thermochemical data obtained from kinetic equilibrium studies agree within the error limits with current photoionization mass spectrometric and ab initio theoretical results.



39    T. Turányi
        Applications of sensitivity analysis to combustion chemistry
        Reliability Engineering & System Safety, 57, 41-48(1997)

Combustion chemical models usually contain several hundred or thousand kinetic rate parameters. Most simulation packages
calculate local concentration sensitivities, but it is frequently not easy to extract meaningful information from
large sensitivity matrices. Principal component analysis is a simple post-processing technique that summarizes sensitivity
information and also reveals the effect of simultaneously changing parameters. A new program package, called KINALC, has
been created for the analysis of gas-phase reaction systems. This program is an extension to CHEMKIN based simulation
programs. KINALC processes the concentration sensitivity information in four different ways and allows a comparison of
the sensitivity information to other methods, based on the study of reaction rates and stoichiometry, for the analysis of
complex mechanisms. KINALC is available through the World Wide Web. The various methods are illustrated by the analysis of a detailed chemical model for hydrogen combustion. Local sensitivity analysis of models of homogeneous hydrogen
explosion and of premixed laminar hydrogen-air flame has been carried out and the sensitivity results reveal that the
chemical processes are very similar in these physically different systems at the corresponding temperatures.



40    T. Turányi
        Reduction of reaction mechanisms on the basis of the repro-modelling approach
        in: Proceedings of the workshop on 'Numerical aspects of reduction in chemical kinetics'
        2nd September, 1997, CERMICS, Paris

41    L.J. Clifford, A.M. Milne, T. Turányi, D. Boulton
        An induction parameter model for shock-induced hydrogen combustion simulations
        Combustion and Flame, 113, 106-118(1998)

An induction parameter model has been constructed for the simulation of shock-induced combustion that incorporates the
repro-modeling approach for the description of the energy release phase. The model applies only explicit, algebraic
functions for the description of the chemical kinetics. These functions parameterize a set of data calculated from
homogeneous combustion simulations using a complete and detailed reaction mechanism. Based on this method a model has
been created for the simulation of shock-induced combustion of hydrogen in an argon atmosphere. The parameterized model
approximates the results of the full chemistry very closely, but the algebraic functions can be computed in a fraction of
the time of the full chemistry solution. We use the parameterized model in one- and two-dimensional reactive flow
simulations. The results simulate experimental results well, including transitions to detonations and the propagation of detonation waves.



42    T. Turányi, H. Rabitz
        Local methods
        in: 'Sensitivity analysis'
        eds: A. Saltelli, K. Chan, M. Scott
        Wiley, Chichester, 2000

FURTHER INFO



43    A. Obieglo, J. Gass, A. Büki, T. Turányi
        PDF-Berechnung einer turbulenten Flamme unter Verwendung des Repromodellierens
        VDI Berichte, 1492, 487-492(1999)

In der Arbeit werden Ergebnisse einer numerischen Simulation einer axialsymmetrischen, turbulenten nichtvorgemischten Wasserstoff-Jet-Flamme präsentiert ud mit experimentellen Daten verglichen. Das Konzept des Repromodellierens wird präsentiert und Resultate einer numerischen Simulation eines perfekt vorgemischten Reaktors mit den Ergebnissen detaillierter Chemie verglichen. Es wird aufgezeigt, wie sich chemische Abläufe mittels Repromodellieren sehr genau beschreibne lassen.
Ebenso wird erläutert, wie gut sich Temperaturen aun Hauptspezies im physikalischen Raum einer turbulenten Verbrennung mittles PDF Mehtode abbilden lassen und wo Limitierungen seitens der Chemie auftreten, wenn ein Ansatz mit Gleichgewichts-Chemie gewählt wird. Die Verwendung des Repromodellierens für den Einsatz in turbulenten Verbrennungsvorgängen wird diskutiert und anhand der Koppelung einer Trasportgleichung für die PDF mit der Methode des Repromodellierens vorgestellt.



44    T. Turányi
        A reakciókinetika néhány újabb eredménye a légkörkémiában és az égéstudományban
        (Some new results of reaction kinetics in atmospheric and combustion chemistry)
        Magy. Kém. Folyóirat, 55, 323-326(2000)

Reaction kinetics plays a central role in atmospheric and combustion chemistry. Recent research in atmospheric chemistry have identified the most sensitive parts of atmosphere and combustion research contributed to the development of environment friendly technologies. Chlorofluorocarbons and halons have proved dangerous and now risk of their surrogates is being assessed. A good surrogate must have a fast reaction with radical OH and the compound and all its decomposition products must be harmless. Sulphate aerosols are among the species that control the IR balance of the Earth. Kinetic pathways from organic sulphur compounds, emitted by marine plants, to aerosols is being studied.
Investigation of the mechanisms of combustion of fuels, like hydrogen and hydrocarbons, and fuel additives, like ethers, aldehydes and ketones, is an active field. Development of low-NOx burners require the exploration of the high temperature reaction kinetics of nitrogen compounds.



45    K.J. Hughes, T. Turányi, A. Clague, M.J. Pilling
        Development and testing of a comprehensive chemical mechanism for the oxidation of methane
        Int.J.Chem.Kinet., 33, 513-538(2001)

A comprehensive chemical mechanism to describe the oxidation of methane has been developed, consisting of 351 irreversible reactions of 37 species. The mechanism also accounts for the oxidation kinetics of hydrogen, carbon monoxide, ethane, and ethene in flames and homogeneous ignition systems in a wide concentration range. It has been tested against a variety of experimental measurements of laminar flame velocities, laminar flame species profiles, and ignition delay times. The highest sensitivity reactions of the mechanism are discussed in detail and compared with the same reactions in the GRI, Chevalier and Konnov mechanisms. Similarities and differences of the four mechanisms are discussed. Our mechanism is available on the World Wide Web as a fully documented CHEMKIN data file at the address http://www.chem.leeds.ac.uk/Combustion/Combustion.html



46    K.J. Hughes, A.S. Tomlin, E. Hampartsoumian, W. Nimmo, I.G. Zsély, M.Ujvári, T. Turányi, A.R. Clague, M.J. Pilling
        An Investigation of Important Gas Phase Reactions of Nitrogen Species from the
        Simulation of Bulk Experimental Data in Combustion Systems
        Combust.Flame, 124, 573-589(2001)

A detailed elementary reaction mechanism for nitrogen containing species in flames consisting of hydrogen, C1 or C2 fuels is presented. Simulation results obtained with this comprehensive NOx mechanism are compared with bulk experimental data obtained for nitrogen containing species in a variety of combustion systems including flow reactors, perfectly stirred reactors, and low pressure laminar flames. Sensitivity analysis has been employed to highlight the important reactions of nitrogen species in each system. The rate coefficients for these reactions have been compared against the expressions used in three other recent reaction mechanisms: version 3.0 of the GRI mechanism, the mechanism of Glarborg, Miller and co-workers, and that of Dean and Bozzelli. Comparisons indicate that there is still a large discrepancy in the reaction mechanisms used to describe nitrogen chemistry in combustion systems. Reactions for which further measurements and evaluations are required are identified and the differences between the major mechanisms available are clearly demonstrated.



47    T. Turányi, T. Perger and L. Balázs
        Reaction-diffusion modelling of cylindrical halogen lamps
        in: High Temperature Materials Chemistry
        Proceedings of the 10th International IUPAC Conference
        held from 10 to 14 April 2000 at the Forschungszentrum Jülich, Germany
        Editors: K. Hilpert, F.W. Froben and L. Singheiser
        Schriften des Forschungszentrum Jülich, Vol. 15, Part I, pp. 321-324, 2000

A detailed chemical kinetic model was produced that described the high temperature oxidative decomposition of CH3Br and HBr, and the formation of tungsten bromide and oxide compounds in halogen lamps. The Xe/Kr/W/Br/C/H/O mechanism consists of 52 reactive species and 395 irreversible reactions. A thermodynamic and transport database was set up for all species of the mechanism.
A computational model was created for stationary modelling of long, cylindrically symmetric halogen lamps. The model calculates the local chemical composition as a function of distance from the filament taking into account thermal reactions, photochemical reactions, ordinary and thermal diffusion. It allows a systematic study of the effect of envelope and filament geometry, filament and wall temperatures, pressure, and composition of the gas on the radial tungsten transport and thus on the lifetime of halogen lamps.



48    István Lagzi, Alison S. Tomlin, Tamás Turányi, László Haszpra, Róbert Mészáros, Martin Berzins
        Modelling Photochemical Air Pollution in Hungary Using an Adaptive Grid Model
        pp. 264-273   in:'Air Pollution Modelling and Simulation', editor: B. Sportisse,
        Springer, Berlin, 2002, ISBN 3-540-42515-2

An adaptive grid model, describing the formation of photochemical oxidants based on triangular unstructured grids, has been developed for the Central European Region. The model automatically places a finer resolution grid in regions were higher numerical error is predicted by the comparison of 1st order and 2nd order solutions. Using this method, grid resolutions of the order of 15 km could be achieved in a computationally effective way. Initial simulation of the photochemical episode August 1998 indicate that the model captures well the spatial and temporal tendencies of ozone production.



49    István Lagzi, Alison S. Tomlin, Tamás Turányi, László Haszpra, Róbert Mészáros, Martin Berzins
        The Simulation of Photochemical Smog Episodes in Hungary and Central Europe Using Adaptive Gridding Models.
        Lecture Notes in Computer Science, 2074,67-76(2001)

An important tool in the management of photochemical smog episodes is a computational model which can be used to test the effect of possible emission control strategies. High spatial resolution of such a model is important to reduce the impact of numerical errors on predictions and to allow better comparison of the model with experimental data during validation. This paper therefore presents the development of an adaptive grid model for the Central European Region describing the formation of photochemical oxidants based on unstructured grids. Using adaptive methods, grid resolutions of less than 20 km can be achieved in a computationally effective way. Initial simulation of the photochemical episode of August 1998 indicates that the model captures the spatial and temporal tendencies of ozone production and demonstrates the effictiveness of adaptive methods for achieving high resolution model predictions.



50    István Gy. Zsély, Tamás Turányi
        Investigation and reduction of two methane combustion mechanisms
        Archivum Combustionis, 21, 173-177(2001)

Analyses of two methane oxidation mechanisms, the GRI mechanism (version 3.0) and the Leeds Methane Oxidation Mechanism (version 1.4), are reported here. Laminar premixed flames were simulated using program PREMIX, and redundant species and the redundant reactions were identified by program KINALC. Two series of reductions were carried out, where the aims were (i) the reproducton of flame speed, flame temperature and major speces concentratons and (ii) the reproducton of also the concentrations of radicals that play an important role in NOx production. The two mechanisms were investigated at fuel lean, stoichiometric and rich conditions. More than one hundred reactions could be eliminated in each case. Simulation results obtained by the reduced mechanisms dffer by a few pertent only from that calculated by the original mechanisms.



51    Tamás Turányi, Lajos Zalotai, Sándor Dóbé, Tibor Bérces
        Effect of the uncertainty of kinetic and thermodynamic data on methane flame simulation results
        Phys.Chem.Chem.Phys,4, 2568-2578(2002)

A method for assessing and comparing the impact of uncertainties in both kinetic and thermodynamic parameters on the predictions of combustion chemistry models has been developed. Kinetic, thermodynamic and overall uncertainty parameters are defined, which allow tracking the sources of uncertainties for a particular model result. The method was applied to premixed laminar methane-air flames using the Leeds Methane Oxidation Mechanism ( K.J. Hughes et al., Int.J.Chem.Kinet., 33, 513-538(2001)).
Heat of formation and rate coefficient data for species and elementary reactions, respectively, related to methane combustion were collected from several recent reviews and critically assessed error limits were assigned to them. Local rate coefficient sensitivities and heat of formation sensitivities were calculated for lean (phi = 0.62), stoichiometric (phi = 1.00) and rich (phi = 1.20) laminar atmospheric premixed methane-air flames. Uncertainties of flame velocity, maximum flame temperature and also the value and location of maximum concentration of radicals H, O, OH, CH and CH2 were obtained from the sensitivities and the uncertainties of thermodynamic and chemical kinetic data. The uncertainty of the calculated flame velocity is typically 2-5 cm/s. Maximum flame temperature and concentration of H, O, and OH can be calculated accurately, while there is high uncertainty in the calculated maximum concentration of CH and CH2.
The calculations have revealed that the uncertainty of the calculated flame velocity is caused mainly by errors of the input rate coefficients. This is the case also for the calculated concentration of CH and CH2. The uncertainty of the location of concentration maxima is also of kinetics origin and it is caused by the very same rate coefficients that affect flame velocity. Uncertainty of maximum adiabatic flame temperature and maximum concentration of H, O and OH originates mainly from errors of the input heat of formation data. In order to obtain good simulation results for methane flames, accurate heats of formation are required in particular for radicals OH, CH2(S), CH2, CH2OH, HCCO and CH2HCO. Simulation results could be improved by better knowledge of the reaction rate parameters for the reactions O2 + H = OH + O, O2 + H + M = HO2 + M, CO + OH = CO2 + H, H + CH3(+M) = CH4(+M), CH3 + OH = CH2(S) + H2O, C2H2 + OH = C2H + H2O and C2H2 + CH = C2H + CH2. This conclusion is somewhat surprising since at least the first three reactions are among the most frequently studied ones in chemical kinetics.
The calculations demonstrate that all simulation results of chemical kinetic modelling studies should be accompanied by uncertainty information (e.g. standard deviation) for the model outputs to indicate which results are well supported by the model and which ones are merely nominal values that were obtained using the selected set of input parameters.



52    A. Büki, T. Perger, T. Turányi, U. Maas
        Repro-modelling Based Generation of Intrinsic Low-dimensional Manifolds
        J.Math.Chem., 31, 345-362(2002)

Effective procedures for the reduction of reaction mechanisms, including the intrinsic low-dimensional manifold (ILDM) and the repro-modelling methods, are all based on the existence of very different time scales in chemical kinetic systems. These two methods are reviewed and the advantages and drawbacks of them are discussed. An algorithm is presented for the repro-modelling based generation of ILDMs. This algorithm produces an unstructured table of ILDM points, which are then fitted using spline functions. These splines contain kinetic information on the behaviour of the chemical system. Combustion of hydrogen in air is used as illustrative example. Simulation results using the fitted model are compared with the outcome of calculations based on the detailed reaction mechanism for homogeneous explosions and 1D laminar flames.



53    István Lagzi, Alison S. Tomlin, Tamás Turányi, László Haszpra, Róbert Mészáros, Martin Berzins
        Modelling Tropospheric Ozone Formation in Hungary using an Adaptive Gridding Method
        Proceedings from the EUROTRAC-2 Symposium 2002, P.M. Midgley, M. Reuters (Eds.),
        Margraf Verlag, Weikersheim, 2002

Previous EUROTRAC investigations have shown that some of the highest regional ozone concentrations in Europe can be observed in Central Europe, including Hungary. Computational models are important tools in the management of photochemical smog episodes because they can be used for testing the effect of various emission control strategies. High spatial resolution of such models is very important to reduce the impact of numerical errors on predictions. Within a UK-Hungarian cooperation project a regional air quality model has been developed that describes the transport and chemical transformation of photochemical oxidants across Central Europe using an adaptive gridding method to achieve high resolution. The basic coarse grid covers a wider Central European region and a nested finer resolution grid covers Hungary. Further refinement of the unstructured triangular grid is invoked during the simulation at intermediate time-steps using spatial error estimators based on the comparison of high and low order numerical solutions of the atmospheric diffusion equation. Using this method, grid resolutions of the order of 20 km can be achieved in a computationally effective way within a domain of 1540 km X 1500 km.



54    T. Perger, T. Kovács, T. Turányi, C. Trevińo
        Determination of adsorption and desorption parameters from ignition temperature measurements
        in catalytic combustion systems
        J.Phys.Chem. B, 107, 2262-2274(2003)

Exposing a cold catalyst to a fuel-oxygen mixture, the surface gets covered with the more effectively adsorbing species. Increasing the temperature, this species is desorbed and the ignition temperature is determined by the rate of desorption. Based on the equations for the heat balance, expressions were derived for the calculation of ignition temperature from the parameters of the experimental setup, the preexponential factor Ad and activation energy Ed of desorption, the ratio of sticking coefficients, and the ratio of adsorption orders of fuel and oxygen. Published experimental data for the catalytic ignition of CO, H2 and CH4 were reinterpreted using the expressions obtained and the following parameters were determined for polycrystalline platinum catalyst: Ed(H2/Pt)=43.3±5.2 kJ/mole, Ed(CO/Pt)= 107.2±12.7 kJ/mole, Ed(O2/Pt)=190±34 kJ/mole, S(H2,0)/S(O2,0) =36.7±9.6, S(CO,0)/S(O2,0) =41.2±8.5, S(O2,0)/S(CH4,0) =5.9±0.3. Error limits refer to confidence level of 0.95. The activation energy of desorption for CO and O2 and the ratio of zero coverage sticking coefficients of O2 and CH4 are the first experimentally based determinations of these parameters. Experimental ignition temperatures could be reproduced assuming second order adsorption of CO, H2 and O2 on Pt surface. These reaction orders have been debated in the literature.



55    I. Gy. Zsély, J. Zádor, T. Turányi
        Similarity of sensitivity functions of reaction kinetic models
         J.Phys.Chem. A, 107, 2216-2238 (2003)

Local sensitivity functions d Y_i/d p_k of many chemical kinetic models exhibit three types of similarity: (i) Local similarity: ratio lambda_ij= (d Y_i/d p_k) /(d Y_j/d p_k ) is the same for any parameter k; (ii) The scaling relation: ratio lambda_ij is equal to (d Y_i/d z) /(d Y_j/d z ) ; (iii) Global similarity: ratio (d Y_i/d p_k) /(d Y_i/d p_m ) is constant in a range of the independent variable z. It is shown that the existence of low-dimensional slow manifolds in chemical kinetic systems may cause local similarity. Th scaling relation is present, if the dynamics of the system is controlled by a one-dimensional slow manifold. The rank of the local sensitivity matrix is less than or equal to the dimension of the slow manifold. Global similarity emerges if local similarity is present and the sensitivity differential equations are pseudohomogeneous. Global similarity means that the effect of the simultaneous change of several parameters can be fully compensated for all variables, in a wide range of the independent variable by changing a single parameter. Therefore, presence of global similarity has far-reaching practical consequences for the "validation" of complex reaction mechanisms, for parameter estimation in chemical kinetic systems, and in the explanation of the robustness of many self-regulating systems.



56    Haszpra L., Lagzi I., Turányi T., Tomlin A.S., Radnóti G.
        Nyári szmog-helyzetek előrejelzése adaptív rácsmodellel
        (Forecast of summer smog episodes using an adaptive grid model, in Hungarian)
        Proceedings of 'Meteorológiai Tudományos Napok 2002'
        pp. 119-123 and Table IXin: , A meteorológiai előrejelzések és alkalmazásaik
        (Forecast in meteorology and its applications), ed: J. Mika,
        Országos Meteorológiai Szolgálat, Budapest, 2002, ISBN 963 7702 86 5

57    Lagzi I., Turányi T., Tomlin A.S., Haszpra L.
        Simulation of the effect of the plume of Budapest on the photochemical air pollutants formation in Hungary
        pp. 55-57 in: Proceedings of the 4th International Conference on Urban Air Quality
        23-27 March, 2003, Prague, R.S. Sokhi and J. Brechler (eds.)

An adaptive grid model that describes the formation and transformation of photochemical oxidants, based on triangular unstructured grids has been developed to study the photochemical air pollution in the Central-European region. The model was applied here to investigate the influence of the emission of Budapest for the ozone concentration around the city. The two typical patterns are that (i) the high ozone precursor emission of Budapest causes a plume-like formation of ozone within about 100 km downwind even if no regional photochemical air pollution episode is present; (ii) in case of a regional zone episode, the large amount of NO emitted in Budapest significantly decreases the ozone concentration in the city. This latter influence is limited to a narrow region of Budapest. The model can be used for the elaboration of integrated ozone concentration maps for each year, which will allow a more comprehensive study of the emission of Budapest.



58    I. Gy. Zsély, J. Zádor and T. Turányi
        local and global similarity of sensitivity vectors of combustion kinetic models
        pp. 849-859 in: Proceedings of the 3rd Mediterranean Combustion Symposium,
        Marrakech, Morocco, June 8-13, 2003

Local sensitivity functions (d Y_i/d p_k) of many chemical kinetic models exhibit three types of similarity: (i) local similarity: ratio lambda_ij= (d Y_i/d p_k) /(d Y_j/d p_k ) is equal for any parameter k; (ii) The scaling relation: ratio lambda_ij is equal to (d Y_i/d z) /(d Y_j/d z ) ; (iii) Global similarity: ratio (d Y_i/d p_k) /(d Y_i/d p_m ) is constant in a range of the independent variable z. Similarities can be detected by calculating the ratios above or, in a more efficient way, via the investigation of the correlations based on the scalar product of the corresponding sensitivity vectors. Local similarity may be a consequence of the existence of low-dimensional slow manifolds in chemical kinetic systems. Scaling relation may be present, if the dynamics of the system is controlled by a one-dimensional slow manifold. Global similarity emerges if local similarity is present and the sensitivity differential equations are pseudo-homogeneous. Global similarity means that the effect of the simultaneous change of several parameters can be fully compensated for all variables, in a wide range of the independent variable by changing a single parameter. The similarity relations are very important from a practical point of view in the fields of the 'validation' of complex reaction mechanisms and parameter estimation of chemical kinetic systems. Global similarity of models can be revealed by the principal component analysis of the sensitivity matrices. The statements are illustrated by numerical examples related to the homogeneous explosion and adiabatic laminar flames of stoichiometric methane-air mixtures.



59    T. Perger, T. Kovács, T. Turányi, C. Trevińo
        Determination of adsorption and desorption parameters from heterogeneous ignition temperature measurements
        pp. 860-870 in: Proceedings of the 3rd Mediterranean Combustion Symposium,
        Marrakech, Morocco, June 8-13, 2003

In heterogeneous combustion, reaction of fuel and oxygen i occurs on a catalyst surface. The surface of a cold catalyst is covered with the more effectively adsorbing species; when the temperature is increased, this species is desorbed, and the rates of adsorption and desorption determine the ignition temperature. Based on the equations for the heat balance, expressions were derived for the calculation of ignition temperature from the parameters of the experimental setup and the physical parameters of adsorption and desorption. These physical parameters are the preexponential factor A_D and activation energy E_D of desorption, the ratio of zero coverage sticking coefficients, and the ratio of adsorption orders of fuel and oxygen. Several published experimental ignition temperature measurements were reanalysed to obtain adsorption-desorption parameters for CO, H2, CH4, C2H4, and C3H6 on polycrystalline platinum catalyst. The following parameters were determined via nonlinear least-squares fitting: activation energies of desorption: E_D(H2/Pt) = 43.3 ± 5.2 kJ/mol, E_D(CO/Pt) = 107.2 ± 12.7 kJ/mol, E_D(O2/Pt) = 190±34 kJ/mol, E_D(C2H4/Pt) = 136 ± 21 kJ/mol, E_D(C3H6/Pt) = 161 ± 53 kJ/mol; ratio of sticking coefficients: S(H2)/S(O2) = 36.7 ± 9.6, S(CO)/S(O2) = 41.2 ± 8.5, S(O2)/S(CH4) = 5.9 ± 0.3, S(C2H4)/S(O2) = 15.6 ± 1.9, S(C3H6)/S(O2) = 11.9 ± 1.7. Error limits refer to a confidence level of 0.95. Experimental ignition temperatures could be reproduced assuming second order adsorption of CO, H2, O2, CH4, C2H4, and C3H6 on polycrystalline platinum. These reaction orders have been debated in the literature.



60    Lagzi I., Nagy T., Turányi T., Haszpra L., Tomlin A.S.
        Simulation of the formation and spread of photochemical air pollution in Hungary
        pp. 495-500 in: Proceedings of the Conference on Modelling Fluid Flow (CMFF'03)
        Budapest, Hungary, September 3 - 6, 2003

An adaptive grid model has been developed to describe the formation of photochemical air pollutants in the Central European region. The modelled region covers an area of 1500 km × 1500 km with Hungary in the centre. Grid resolution in critical places can be as fine as 6 km. Vertical stratification of the troposphere, up to 3000 meters, is described by using four layers. The meteorological data used were obtained from the weather forecast model ALADIN of the Hungarian Meteorological Service. Simulation results are presented for a smog episode of 3rd and 4th August, 1998.



61    Kovács T., Turányi T.
        Modelling of the decomposition of CCl4 in thermal plasma
        in: Proceedings of the 2nd International Meeting on Chemistry,
        3-6 June, 2003, Santa Clara, Cuba
        ISBN 959-250-080-0

Perhalogenated hydrocarbons were popular materials in many areas of the chemical industry and in the household. Their applications have been banned by international treaties because of their stratospheric ozone depleting property. However, large quantities are still stored waiting for a safe decomposition technology. Many experimental articles were published in the last few years showing that plasma technology is applicable for the decomposition of halogenated hydrocarbons in an environmentally friendly way. We have modelled the kinetics of the decomposition of carbon tetrachloride in thermal plasma in argon bulk gas in the temperature range of 300 K to 7000 K. The reaction mechanism contains 34 irreversible reaction steps and 12 species. The thermodynamic data and the kinetic parameters were obtained from Burcat's Thermodynamic Database and the NIST Chemical Kinetics Database, respectively. The conditions of the modelling were in accordance with that was used in a recent experimental paper of Föglein et al. to allow the comparison of the modelling and the experimental results. The modelled reactor was an inductively coupled plasma (ICP) reactor. The CCl4/Ar mixture was injected to the high temperature (7000 K) region of the reactor. The modelled temperature profile was in accordance with that of the laboratory reactor. The kinetic calculations provided the concentration-time profiles for each species. All initial carbon tetrachloride was consumed within a few microseconds, but a part of the CCl4 was regenerated from the decomposition products. Our calculations predicted 70% net conversion of CCl4 , which is close to the experimentally determined 60%. Apart from the regenerated CCl4 , other main products of the incineration were C2Cl2 and Cl2. The simulations were also repeated by a thermodynamic equilibrium model. Results of the kinetic and thermodynamic modelling were in good accordance above 2000 K, but our calculations showed that below 2000 K the thermodynamic equilibrium model gave wrong predictions. Therefore, application of detailed kinetic mechanisms is recommended in the modelling of plasma incineration of harmful materials. Similar modelling studies can be used for planning efficient plasma reactors for incineration technologies.



62    R. Deters, H. Gg. Wagner, Á. Bencsura, K. Imrik, S. Dóbé, T. Bérces, F. Márta, F. Temps, T. Turányi, I. Gy. Zsély
        Direct kinetic determination of rate parameters for the reaction CH3 + OH. Implications for methane flame modelling
        Proceedings of the European Combustion Meeting 2003, Paper No 21
       

Kinetics of the overall reaction CH3 + OH (1) were studied close to the high-pressure limit using the laser flash photolysis/transient UV absorption method (LFP/TAS) and in the fall-off regime with discharge flow/far infrared laser magnetic resonance (DF/LMR) at 298 K and 473 K, respectively. The product channel 1CH2 + H2O (1.1) was also studied with the DF/LMR method. The following rate constants and branching ratio were determined (in He): k1 (1463 mbar, 298 K) >= 6.2 10(13) cm3 mol-1 s-1 , k1 (1.16 mbar, 473 K) >= 5.2 10(13) cm3 mol-1 s-1 and k1.1 / k1 > 0.7 (1.16 mbar, 473 K). Flame velocity for a standard CH4-air flame was calculated in relation to the kinetics results.



63    I. Gy. Zsély, J. Zádor, T. Turányi
        Uncertainty analysis backed development of combustion mechanisms
        Proceedings of the European Combustion Meeting 2003, Paper No 35

Uncertainty analysis was used to back the development of H2/air and wet CO/air combustion mechanisms. The Leeds Methane Oxidation Mechanism was updated on the basis of the latest literature data. Uncertainties of the simulation results, caused by the uncertainties of the kinetic parameters and the heat of formation data, were analysed. The methods used were local uncertainty analysis and Monte Carlo Analysis with Latin Hypercube Sampling. There was always satisfactory agreement between the simulation results and the bulk experimental data, but in some cases the uncertainties of the simulation results were large.



64    I. Gy. Zsély, T. Turányi
        The influence of thermal coupling and diffusion on the importance of reactions:
        The case study of hydrogen-air combustion
        Phys.Chem.Chem.Phys., 5, 3622-3631(2003)

Detailed chemical kinetic mechanisms are usually developed on the basis of spatially homogeneous calculations, but utilized in the simulation of very complex physical models. A fundamental question is if the importance of reactions is determined solely by the temperature and the actual concentration set or if it is also influenced by the thermal and diffusion couplings present in the physical model. A 46-step detailed mechanism of hydrogen oxidation was studied at equivalence ratios 0.5, 1.0, 2.0, and 4.0. Six physical models were designed (homogeneous explosion, burner-stabilized and freely propagating laminar flames, with and without thermal coupling), which provided very similar concentration curves as a function of temperature, while the local sensitivity functions revealed that the couplings in these models were very different. The importance of the reactions in every model was investigated by the principal component analysis of the rate sensitivity matrix F (PCAF method), exploiting that the results of this method depend only on the concentrations and temperature. A fundamentally different method, the principal component analysis of the local sensitivity matrix S (PCAS method) was used to extract information on the importance of reactions from the sensitivity functions. The PCAF and PCAS methods selected identical reduced mechanisms at all conditions, which shows that these are equally effective methods for determining a minimal reduced mechanism. The good agreement between the results of the two methods in the case of all models demonstrated that the importance of reactions was independent of the physical model the mechanism had been embedded into. Thermal coupling did not have an effect on the selection of the reduced mechanisms. Difference between the importance of reactions in explosions and flames were caused by the difference of the concentrations in the low-temperature regions and not by the presence of diffusion. The reduced mechanisms contained 15 to 28 reaction steps, depending on the equivalence ratio and the type of the model. All species were retained in models of the combustion of lean and stoichiometric mixtures, while species H2O2 could be eliminated at rich conditions. Description of near stoichiometric conditions required more reaction steps, while rich combustion could be described by few reactions. An overall reduced mechanism, applicable in a wide range of conditions, contained 31 reaction steps. Results of the PCAS method revealed the global similarity relations of the sensitivity matrices of adiabatic explosions.
       



65    I. Lagzi, D. Kármán, T. Turányi, A.S. Tomlin, L. Haszpra
        Simulation of the dispersion of nuclear contamination using an adaptive Eulerian grid model
        J. Environm. Radioact., 75, 59-82(2004)

Application of an Eulerian model using layered adaptive unstructured grids coupled to a meso-scale meteorological model is presented for modelling the dispersion of nuclear contamination following the accidental release from a single but strong source to the atmosphere. The model automatically places a finer resolution grid, adaptively in time, in regions were high spatial numerical error is expected. The high-resolution grid region follows the movement of the contaminated air over time. Using this method, grid resolutions of the order of 6 km can be achieved in a computationally effective way. The concept is illustrated by the simulation of hypothetical nuclear accidents at the Paks NPP, in Central Hungary. The paper demonstrates that the adaptive model can achieve accuracy comparable to that of a high-resolution Eulerian model using significantly less grid points and computer simulation time.



66    J. Zádor, I. Gy. Zsély, T. Turányi
        Investigation of the correlation of sensitivity vectors of hydrogen combustion models
        Int.J.Chem.Kinet., 36, 238-252(2004)

A well-established method for the analysis of large reaction mechanisms is the calculation and interpretation of the sensitivity of the kinetic model output Yi to parameter changes. Comparison of the sensitivity vectors si = {dYi /dp} belonging to differentmodel outputs is a new tool for kinetic analysis. The relationship of the sensitivity vectors was investigated in homogeneous explosions, freely propagating and burner-stabilized laminar flames of hydrogen-air mixtures, using either calculated adiabatic or constrained temperature profiles, for fuel-to-air ratios phi = 0.5-4.0. Sensitivity vectors are called locally similar, if the relationship s_i = lambda_ij*s_j is valid, where lambda_ij is a scalar. In many systems, only approximate local similarity of the sensitivity vectors exists and the extent of it can be quantified by using an appropriate correlation function. In the cases of adiabatic explosions and burner-stabilized flames, accurate local similarity was present in wide ranges of the independent variable (time or distance), and the correlation function indicated that the local similarity was not valid near the concentration extremes of the corresponding species. The regions of poor similarity were studied further by cobweb plots. The correlation relationships found could be interpreted by the various kinetic processes in the hydrogen combustion systems. The sensitivity vector of the laminar flame velocity is usually considered to be characteristic for the whole combustion process. Our investigations showed that the flame velocity sensitivity vector has good correlation with the H and H2O concentration sensitivities at the front of the adiabatic flames, but there is poor correlation with the sensitivity vectors of all concentrations in homogeneous explosions.



67    R. Lovas, P. Kacsuk, I. Lagzi, T. Tur nyi
        Unified development solution for cluster and grid computing and its application in chemistry
        Lecture Notes Comp. Sci., 3044, 226-235(2004)

P-GRADE programming environment provides high-level graphical support to develop parallel applications transparently for both the parallel systems and the Grid. This paper gives an overview on the parallelisation of a simulation algorithm for chemical reaction-diffusion systems applying P-GRADE environment at all stages of parallel program development cycle including the design, the debugging, the execution, and the performance analysis. The automatic checkpoint mechanism for parallel programs, which supports the migration of parallel jobs between different clusters, together with the application monitoring facilities of P-GRADE enable the long-running parallel jobs to run on vARious non-dedicated clusters in the Grid while their execution can be visualised on-line for the user. The presented research achievements will be deployed in a chemistry Grid environment for air pollution forecast.



68     T. Turányi, I. Gy. Zsély, and J. Zádor
        Selforganization in high temperature reaction kinetic systems
        pp. 134-137, in: Proceedings of the conference "Selforganization in nonequilibrium systems"
        (Belgrade, September 24-25, 2004), ISBN: 86-82475-15-4

Models of homogeneous explosions and one-dimensional laminar flames of hydrogen and methane were analysed by a series of mathematical tools. The results indicated that the real dynamical dimension of these systems is 1 to 3, while the number of variables is from 10 to 38. This dimension reduction indicates strong couplings in the model, exhibited in the similarity relations among the sensitivity functions. It has consequences in areas of practical importance, like determination of rate parameters from experimental data or search for a minimal equivalent model.



69     I. Gy. Zsély, J. Zádor, T. Turányi
        Uncertainty analysis of updated hydrogen and carbon monoxide oxidation mechanisms
        Proc. Combust. Inst., 30, 1273-1281(2004)

Uncertainty analysis was used to investigate H2/air and wet CO/air combustion mechanisms. The hydrogen/carbon monoxide submechanism of the Leeds Methane Oxidation Mechanism was updated on the basis of the latest reaction kinetics and thermodynamics data. The updated mechanism was tested against three hydrogen oxidation and two wet CO bulk experiments. Uncertainties of the simulation results, caused by the uncertainties of the kinetic parameters and the heat of formation data, were analysed. The methods used were the local uncertainty analysis and Monte Carlo analysis with Latin hypercube sampling. The simulated flame velocity had relatively large uncertainty in both hydrogen-air and wet CO flames. In the case of ignition experiments, for both fuels the uncertainties of the simulated ignition delay times were small and comparable with the scatter of the experimental data. There was a good agreement between the simulation results and the measured temperature and concentration profiles of hydrogen oxidation in a flow reactor. However, accurate ignition delay is not a result of the flow reactor experiments. The uncertainty of the required time correction for matching the simulated 50% consumption of H2 to that of the experimental one (corresponding to the simulated ignition delay) was found to be very large. This means that very different parameter sets provide very different ignition delays, but very similar concentration curves after the time correction. Local uncertainty analysis of the wet CO flame revealed that uncertainties of the rate parameters of reactions O2 + H (+M) = HO2 (+M), and CO + OH = CO2 + H cause high uncertainty to the calculated flame velocity, temperature, and peak concentrations of radicals. Reaction H + HO2 = H2 + O2 also causes high uncertainty for the calculated flame velocity. The uncertainty of the enthalpy of formation of OH is highly responsible for the uncertainty of the calculated peak OH concentration.



70     I. Lagzi, R. Mészáros, L. Horváth, A.S. Tomlin, T. Weidinger, T. Turányi, F. Ács, L. Haszpra
        Modelling ozone fluxes over Hungary
        Atm. Environm., 38, 6211-6222 (2004)

This paper presents and utilises a coupled Eulerian photochemical reaction-transport model and a detailed ozone dry-deposition model for the investigation of ozone fluxes over Hungary. The reaction-diffusion-advection equations relating to ozone formation, transport and deposition are solved on an unstructured triangular grid using the SPRINT2D code. The model domain covers Central Europe including Hungary, which is located at the centre of the domain and is covered by a high-resolution nested grid. The sophisticated dry-deposition model estimates the drydeposition velocity of ozone by calculating the aerodynamic, the quasi-laminar boundary layer and the canopy resistance. The meteorological data utilised in the model were generated by the ALADIN meso-scale limited area numerical weather prediction model used by the Hungarian Meteorological Service. The ozone fluxes were simulated for three soil wetness states, corresponding to wet, moderate and dry conditions. The work demonstrates that the spatial distribution of ozone concentration is a less accurate measure of effective ozone load, than the spatial distribution of ozone fluxes. The fluxes obtained show characteristic spatial patterns, which depend on the soil wetness, the meteorological conditions, the ozone concentration and the underlying land use.



71     J. Zádor, I. Gy. Zsély, T. Turányi
        Local and global uncertainty analysis of complex chemical kinetic systems
        Rel. Engng. Syst. Safety, in press

Computer modelling plays a crucial part in the understanding of complex chemical reactions. Parameters of elementary chemical and physical processes are usually determined in independent experiments and are always associated with uncertainties. Two typical examples of complex chemical kinetic systems are the combustion of gases and the photochemical processes in the atmosphere. In this study, local uncertainty analysis, the Morris method, and Monte Carlo analysis with Latin hypercube sampling were applied to an atmospheric and to a combustion model. These models had 45 and 37 variables along with 141 and 212 uncertain parameters, respectively. The toolkit used here consists of complementary methods and is able to map both the sources and the magnitudes of uncertainties. In the case of the combustion model, the global uncertainties of the local sensitivity coefficients were also investigated, and the order of parameter importance based on local sensitivities were found to be almost independent of the parameter values within their range of uncertainty.



72     I. Lagzi, R. Lovas, T. Turányi
        Development of a Grid enabled chemistry application,
        in: Distributed and Parallel Systems: Cluster and Grid Computing, Z. Juhasz; P. Kacsuk; D. Kranzlmuller (Eds.)
        The Kluwer International Series in Engineering and Computer Science,
        777, 137-144(2004), ISBN: 0-387-23094-7

P-GRADE development and run-time environment provides high-level graphical support to develop scientific applications and to execute them efficiently on various platforms. This paper gives a short overview on the parallelization of a simulator algorithm for chemical reaction-diffusion systems. Applying the same user environment we present our experiences regarding the execution of this chemistry application on nondedicated clusters, and in different grid environments.



73     T. Kovács, T. Turányi, K. Föglein, J. Szépvölgyi
        Kinetic modelling of the decomposition of carbon tetrachloride in thermal plasma
        Plasma Chemistry and Plasma Processing, 25, 109-119(2005)

Decomposition of carbon tetrachloride in a RF thermal plasma reactor was investigated under neutral conditions. The net conversion of CCl4 and the main products of its decomposition were determined from the mass spectrometric analysis of outlet gases. Flow and temperature profiles in the reactor were calculated and concentration profiles of the species along the axis of the reactor were estimated using a newly developed chemical kinetic mechanism, containing 12 species and 34 reaction steps. The simulations indicated that all carbon tetrachloride decomposed within a few mi-croseconds. However, CCl4 was partly recombined from its decomposition products. The calculations predicted 70 % net conversion of CCl4, which was close to the experimentally determined value of 60 %. The decomposition was also simulated by a thermodynamic equilibrium model. Re-sults of the kinetic and thermodynamic simulations agreed well above 2000 K. However, below 2000 K the thermodynamic equilibrium model gave wrong predictions. Therefore, application of detailed kinetic mechanisms is recommended for modelling CCl4 decomposition under thermal plasma conditions.



74     T. Perger, T. Kovács, T. Turányi, C. Trevińo
        Determination of the adsorption and desorption parameters for ethene and propene
         from measurements of the heterogenous ignition temperature
        Combustion and Flame, 142, 107-116(2005)

If a cold catalyst is exposed to a mixture of fuel + oxygen, the surface coverage of the catalyst can be dominated by either the fuel or the oxygen, depending on the actual catalyst and the composition of the gaseous mixture. If the temperature is increased, heterogeneous ignition occurs; the ignition temperature is influenced by the adsorption and desorption properties of both the fuel and the oxygen. Based on the equations for the heat balance, expressions have been derived for calculating the ignition temperature from the parameters of the experimental setup and the adsorption and desorption parameters of the fuel and the oxygen. These expressions can also be used to evaluate measured ignition temperatures to determine unknown adsorption and desorption parameters, such as: the pre-exponential factor AD and activation energy ED for the desorption of the dominant surface species, the ratio of the sticking coefficients and the ratio of adsorption orders of fuel and oxygen. This latter approach was used to evaluate measurements made by Cho and Law for the catalytic ignition of ethene and propene on polycrystalline platinum. The following parameters were determined by means of nonlinear least-squares fitting: ED(C2H4/Pt) = 136 ± 21 kJ/mol, ED(C3H6/Pt) = 161 ± 53 kJ/mol; S(C2H4,0)/S(O2,0)= 15.6 ± 1.9, S(C3H6,0)/S(O2,0)= 11.9 ± 1.7. Using a previously determined value for the sticking coefficient of O2, the values S(C2H4,0)= 0.38 ± 0.08 and S(C3H6,0)= 0.29 ± 0.06 were obtained. These error limits refer to a confidence level of 0.95. Experimental ignition temperatures could be reproduced assuming second order adsorption of ethene and propene on a surface of Pt.



75     I. Gy. Zsély, J. Zádor, T. Turányi
        On the similarity of the sensitivity functions of methane combustion models
        Combustion Theory and Modelling, 9, 721-738(2005)

It is widely known that detailed kinetic mechanisms with identical reaction steps but with very different rate parameters may provide similar simulation results in combustion calculations. This phenomenon is related to the similarity of sensitivity functions, which arises if low-dimensional manifolds in the space of variables, and autocatalytic processes are present. We demonstrated the similarity of sensitivity functions for adiabatic explosions and burner-stabilized laminar flames of stoichiometric methane.air mixtures. The cause of similarities was investigated by calculating the dimension of the corresponding manifolds, and the pseudo-homogeneous property of the sensitivity ODE. The methane explosion model showed global similarity, which means that different parameter sets could provide the same simulation results. This was demonstrated by numerical experiments, in which two significantly different parameter sets resulted in identical concentration profiles for all species. This is important from a practical point of view in the fields of the .validation. of complex reaction mechanisms and the parameter estimation of chemical kinetic systems.



76     J. Zádor, I. Gy. Zsély, T. Turányi, Marco Ratto, Stefano Tarantola, Andrea Saltelli
        Local and global uncertainty analyses of a methane flame model
        J. Phys. Chem. A, 109, 9795-9807(2005)

Local and global uncertainty analyses of a flat, premixed, stationary, laminar methane flame model were carried out using the Leeds methane oxidation mechanism at lean (phi = 0.70), stoichiometric (phi = 1.00) and rich (phi = 1.20) equivalence ratios. Uncertainties of laminar flame velocity, maximal flame temperature, and maximal concentrations of radicals H, O, OH, CH and CH2 were investigated. Global uncertainty analysis methods included the Morris method, the Monte Carlo analysis with Latin hypercube sampling and an improved version of the Sobol' method. Assumed probability density functions (pdf) were assigned to the rate coefficients of all the 175 reactions and to the enthalpies of formation of the 37 species. The analyses provided the following answers: approximate pdfs and standard deviations of the model results, minimum and maximum values of the results at any physically realistic parameter combination, and the contribution of the uncertainty of each parameter to the uncertainty of the model result. The uncertainty of few rate parameters and few enthalpies of formation data cause most of the uncertainty of model results. Most uncertainty comes from the inappropriate knowledge of kinetic data, but the uncertainty caused by thermodynamic data is also significant.



77     I. Gy. Zsély, I. Virág, T. Turányi
        Investigation of a methane oxidation mechanism via the visualization of element fluxes
        Paper IX.4 in: Proceedings of the 4th Mediterranean Combustion Symposium,
        Lisbon, Portugal, 5-10 October, 2005
        Editors: F. Beretta, N. Selçuk, M.S. Mansour

Reaction pathway analysis is a frequently applied tool in the analysis and reduction of reaction mechanisms. Investigation of element fluxes is a rigorous way of kinetic pathway analysis. Code KINALC has been available for the post-processing of the output files of the CHEMKIN simulation programs. However, plotting the element flux figures provided by KINALC is very human time consuming, therefore a new reaction kinetics visualization tool, called FluxViewer has been developed. FluxViewer presents the species as boxes and the interconnecting reactions as arrows. Location of the boxes and the number of the arrows can be optimized in an interactive way. Development of oxidation processes in reactors and flames can be viewed as a movie. The investigation of the Leeds Methane Oxidation Mechanism via element flux analysis, using KINALC and FluxViewer is presented at plug-flow and premixed flame conditions, at several fuel-to-air ratios. Both KINALC and FluxViewer are freely available from Web address: http://garfield.chem.elte.hu/Combustion/Combustion.html



78     T. Kovács, T. Turányi, K. Föglein, J. Szépvölgyi
        Modelling of carbon tetrachloride decomposition in oxidative RF thermal plasma
        Plasma Chemistry and Plasma Processing26, 293-318(2006)

Decomposition of carbon tetrachloride in a RF thermal plasma reactor was investigated in oxygen-argon atmosphere. The net conversion of CCl4 and the main products of decomposition were determined by GC-MS (Gas Chromatographic Mass Spectroscopy) analysis of the exhaust gas. Temperature and flow profiles had been determined in computer simulations and were used for concentration calculations. Concentration profiles of the species along the axis of the reactor were calculated using a newly developed chemical kinetic mechanism, containing 34 species and 134 irreversible reaction steps. Simulations showed that all carbon tetrachloride decomposed within a few microseconds. However, CCl4 was partly recombined from its decomposition products. Calculations predicted 97.9 % net conversion of carbon tetrachloride, which was close to the experimentally determined value of 92.5%. This means that in RF thermal plasma reactor much less CCl4 was reconstructed in oxidative environment than using an oxygen-free mixture, where the net conversion had been determined to be 61%. The kinetic mechanism could be reduced to 55 irreversible reaction steps of 26 species, while the simulated concentrations of the important species were within 0.1% identical compared to that of the complete mechanism.



79     I. Lagzi, A. S. Tomlin, T. Turányi, L. Haszpra
        Photochemical air pollutant formation in Hungary using an adaptive gridding technique
        Int.J. Environment and Pollution, 36, 44-58(2009)

A regional air quality model has been developed that describes the transport and chemical transformation of photochemical oxidants across Central Europe using an adaptive gridding method to achieve high spatial resolution. High-resolution emission inventories for Budapest and Hungary were utilised. The air pollution episode in August 1998 was modelled using a
fixed coarse grid (mesh size 70 km) a fixed fine grid (17.5 km) and an adaptive, variable sized (from 17.5 to 70 km) grid. The fine and the adaptive grid models provided similar results, but the latter required 50% longer computing time. High ozone concentrations appeared downwind of Budapest and the plume extended up to about 150 km from the city at 17.00 on the simulated day. The simulation results were compared with ozone concentrations measured at the K-puszta and Hortobágy monitoring stations.



80     R. Mészáros, D. Szinyei, Cs. Vincze, I. Lagzi, T. Turányi, L. Haszpra, A. S. Tomlin
        Effect of the soil wetness state on the stomatal ozone fluxes over Hungary
        Int.J. Environment and Pollution36, 180-194(2009)

A coupled Eulerian photochemical reaction-transport model and a detailed ozone dry deposition model have been utilised for the estimation of stomatal ozone fluxes over Hungary. Ozone concentrations were modelled on an unstructured triangular grid using a method of lines approach to the solution of the reaction−diffusion−advection equations describing ozone formation, transport and deposition. The model domain covers Central-Europe including Hungary, which was located at the centre of the domain and covered by a high resolution nested grid. The dry deposition velocity of ozone was calculated based on the aerodynamic, quasi-laminar boundary layer and canopy resistance. The effect of soil water content on the stomatal ozone flux was analysed. The stomatal ozone flux calculations were performed for two cases, with and without taking into account the effect of the soil moisture stress on the ozone deposition. The meteorological data were generated by the ALADIN meso-scale limited area numerical weather prediction model. It was found that soil water deficiency can strongly reduce the stomatal conductance and hence the ozone flux through it.
81     J. Zádor, T. Turányi,  K. Wirtz, M. J. Pilling
        Measurement and investigation of chamber radical sources in the European Photoreactor (EUPHORE)        
        J. Atmos. Chem., 55, 147-166(2006)

It is essential to quantify the background reactivity of smog-chambers, since this might be the major limitation of experiments carried out at low pollutant concentrations typical of the polluted atmosphere. Detailed investigation of three chamber experiments at zero-NOx in the European Photoreactor (EUPHORE) were carried out by means of rate-of-production analysis and two uncertainty analysis tools: local uncertainty analysis and Monte Carlo simulations with Latin hypercube sampling. The chemical mechanism employed was that for methane plus the inorganic subset of the Master Chemical Mechanism (MCMv3.1). Newly installed instruments in EUPHORE allowed the measurement of nitrous acid and formaldehyde at sub-ppb concentrations with high sensitivity. The presence of HONO and HCHO during the experiments could be explained only by processes taking place on the FEP Teflon walls. The HONO production rate can be described by the empirical equation W(HONO, dry, EUPHORE) = a × j ×exp( −T/ T0) in the low relative humidity region (RH<2%, a=7.3×10^21 cm–3, T0=8945 K), and by the equation W(HONO, humid, EUPHORE) = W(HONO, dry, EUPHORE) + j(NO2) ×b × RH^q in the higher relative humidity region (2%<RH<15%, b = 5.8×10^8 cm–3 and q = 0.36, and RH is the relative humidity in percentages). For HCHO the expression W(HCHO, EUPHORE) = c × j(NO2) × exp(−T/T0) is applicable (c = 3.1×10^17 cm–3 and T0= 5686K). In the 0-15% relative humidity range OH production from HONO generated at the wall is about a factor of two higher than that from the photolysis of 100 ppb ozone. Effect of added NO2 was found to be consistent with the dark HONO formation rate coefficient of MCMv3.1.


82    R. Lovas, J. Patvarczki, P. Kacsuk, I. Lagzi, T. Turányi, L. Kullmann, L. Haszpra, R. Mészaros, A. Horányi, A. Bencsura, Gy.Lendvay:
        Air pollution forecast on the HUNGRID infrastructure
        Gerhard R. Joubert, Wolfgang E. Nagel, Frans J. Peters, Oscar G. Plata, P. Tirado, Emilio L. Zapata (Eds.), ISBN 3-00-017352-8
        Parallel Computing: Current & Future Issues of High-End Computing, John von Neumann Institute for Computing, Julich, Germany 2005,
        NIC Series, 33, 121-128(2006)

Computational Grid systems are gaining more and more attention in the natural sciences but very often the end-users (biologists, chemists, physics) must tackle various problems when they want to deploy such systems. In this paper a unied software development family is presented, which is able to cover each stage of parallel software development as well as the seamless application migration from parallel systems to Grid platforms. Besides the recently established HUNGRID infrastructure, the development life-cycle is also presented through two air-pollution modelling applications, which enable the authorities to prevent the harmful effects of high-level ozone concentration and accidental releases. The developed computational models can play crucial role in the management of the photochemical smog episodes; they can be used to test the effects of the ozone uxes and possible emission control strategies and accidents.



83    T. Kovács, I. Gy. Zsély, Á. Kramarics, T. Turányi 
         Kinetic analysis of mechanisms of complex pyrolytic reactions
         J. Anal. Appl. Pyrolysis, 79, 252-258(2007)
       
Detailed reaction mechanisms are available for the description of the pyrolysis of many compounds. These mechanisms may consist of hundreds of species and thousands of reactions. Effective analysis of large reaction mechanisms includes uncertainty analysis, which provides information on the reliability of the mechanism and reaction flux analysis, which facilitates the chemical understanding of the process. Reduction of large mechanisms may include the detection and elimination of redundant species and reactions. Another branch of methods, like the QSSA, ILDM, or repro-modelling utilize the very different timescales that are usually present in chemical kinetic systems.
The methane pyrolysis mechanism of Dean et al. containing 1604 irreversible reactions of 189 species was investigated at atmospheric pressure and 1100 K temperature. According to uncertainty analysis, for this system the rate coefficients of all crucial reaction steps are relatively well known. This mechanism was reduced to 338 reactions of 62 species, which could be simulated 11.5 times faster, while the calculated concentration profiles of the mainproducts remained almost identical.Dimension analysis revealed that the process could be modelled by a system of differential equations having 18 variables only. These results were obtained using computer codes KINALC, MECHMOD and FluxViewer, which are freely available through theWeb.


84    A. Lovrics, A. Csikász-Nagy, I. Gy. Zsély, J. Zádor, T. Turányi, B Novák
        Time scale and dimension analysis of a budding yeast cell cycle model
        BMC Bioinformatics, 7:494(2006) 
 

The progress through the eukaryotic cell division cycle is driven by an underlying molecular regulatory network. Cell cycle progression can be considered as a series of irreversible transitions from one steady state to another in the correct order. Although this view has been put forward some time ago, it has not been quantitatively proven yet. Bifurcation analysis of a model for the budding yeast cell cycle has identified only two different steady states (one for G1 and one for mitosis) using cell mass as a bifurcation parameter. By analyzing the same model, using different methods of dynamical systems theory, we provide evidence for transitions among several different steady states during the budding yeast cell cycle. By calculating the eigenvalues of the Jacobian of kinetic differential equations we have determined the stability of the cell cycle trajectories of the Chen model. Based on the sign of the real part of the eigenvalues, the cell cycle can be divided into excitation and relaxation periods. During an excitation period, the cell cycle control system leaves a formerly stable steady state and, accordingly, excitation periods can be associated with irreversible cell cycle transitions like START, entry into mitosis and exit from mitosis. During relaxation periods, the control system asymptotically approaches the new steady state. We also show that the dynamical dimension of the Chen’s model fluctuates by increasing during excitation periods followed by decrease during relaxation periods. In each relaxation period the dynamical dimension of the model drops to one, indicating a period where kinetic processes are in steady state and all concentration changes are driven by the increase of cytoplasmic growth.We apply two numerical methods, which have not been used to analyze biological control systems. These methods are more sensitive than the bifurcation analysis used before because they identify those transitions between steady states that are not controlled by a bifurcation parameter (e.g. cell mass). Therefore by applying these tools for a cell cycle control model, we provide a deeper understanding of the dynamical transitions in the underlying molecular network.


85    I Lagzi, R Mészáros, F Ács, A S Tomlin, L Haszpra, T Turányi
        Description and evaluation of a coupled Eulerian transport-exchange model: Part I. Model development
        Idöjárás, 110, 349-363 (2006)




86    Á. Kramarics, I. Gy. Zsély, T. Turányi
        Analysis of a methane partial oxidation mechanism relevant
at the conditions of the anode channels of a solid-oxide fuel cell
        Proceedings of the European Combustion Meeting 2007, Paper 13-6


87        T. Kovács, T. Turányi, K. Föglein, J. Szépvölgyi
                Comparison of the efficiencies and kinetic analysis of the carbon tetrachloride decomposition in RF thermal plasma in inert and oxidative environments
                Proceedings of the 18th International Symposium on Plasma Chemistry (ISPC), Kyoto, Japan, 26-31 August, 2007

Decomposition of carbon tetrachloride was investigated in an RF inductively coupled thermal plasma reactor in inert CCl4-Ar and in oxidative CCl4-O2-Ar systems. The exhaust gas mixtures were analyzed by GC-MS. Kinetics of CCl4 decomposition at the experimental conditions was modeled in the temperature range of 300 K – 7000 K. Kinetic analysis was performed on the basis of atom fluxes.


88    T. Turányi
        Sensitivity analysis in chemical kinetics (editorial)
        Int.J.Chem.Kinet.,  40, 685-686 (2008)
 
The Fifth International Conference on Sensitivity Analysis of Model Output (SAMO 2007) was held from 18 to 22 June, 2007 at the Eötvös University (ELTE), Budapest, Hungary.  Sensitivity analysis investigates how a model depends on its input parameters. SAMO is a series of conferences devoted to the development and applications of sensitivity analysis methods. These methods are widely used in chemistry, physics, biology, engineering, environmental science, nuclear and industrial safety, and economics. The abstracts of all presented works and the slides of most lectures are available at the conference Web site: http://samo2007.chem.elte.hu/  The special issue contains  seven works that were originally presented at the SAMO 2007 conference:


89    A. Lovrics, I. Gy. Zsély, A. Csikász-Nagy, J. Zádor, T. Turányi, B. Novák
        Analysis of a budding yeast cell cycle model using the shapes of local sensitivity functions
        Int.J.Chem.Kinet., 40, 710-720 (2008)

The Chen et al. (2000) budding yeast cell cycle model is a biochemical kinetic model that describes how the controlling protein concentrations change during a proliferation cycle. Time dependence of local sensitivity coefficients was calculated for all variables and parameters of the model. Some of the local sensitivity coefficient – time functions could also be obtained from another one by multiplying it with a constant, which means that these functions exhibit global similarity. Local similarity of the sensitivity functions were also detected. The distance of the shapes of two scaled sensitivity functions was defined by the integrated squared difference of these functions. The distance matrices of function shapes were interpreted by a clustering method and the shapes could be sorted to two main groups for each model variable. Presence of the global similarity of sensitivity functions means that the change of some enzyme activities can be fully compensated by changing the activity of other enzymes. This feature can be related to the robustness of living organisms.
 

90    I. Gy. Zsély, J. Zádor, T. Turányi
        Uncertainty analysis of NO production during methane combustion
        Int.J.Chem.Kinet., 40, 754-768 (2008)
   
Local and Monte Carlo uncertainty analyses of NO production during methane combustion were carried out, investigating the effect of uncertainties of kinetic parameters and enthalpies of formation. In Case I, the original Leeds Methane Oxidation Mechanism with the NOx reaction block was used, but the enthalpies of formation of all species were updated. In Case II, the NCN-containing reactions of the prompt NO formation route were added and the rate parameters of several reactions were also updated. The NO production was examined at the conditions of the Bartok et al. experiments (PSR, = 1565-1989 K,  phi = 0.8-1.2, residence time 3 ms). The Monte Carlo analysis provided the approximate probability density function (pdf) and the variance of the calculated NO concentration, and also its attainable minimum and maximum values. Both mechanisms provided similarly good to acceptable agreement with the experimental results for lean and stoichiometric mixtures, while only mechanism Case II could reproduce the experimental data for rich mixtures after a realistic tuning of the parameters. Local uncertainty analysis was used to assess the contribution of the uncertainty of each parameter to the uncertainty of the calculated NO concentration. Enthalpies of formation of NNH and HCCO, and rate parameters of 20 reaction steps cause most of the uncertainty of the calculated NO concentrations at all conditions. The relative importance of the four main NO formation routes was investigated via the inspection of the reaction rates, embedded in the Monte Carlo analysis. NO formation in rich mixtures was dominated by the prompt route, while in leaner mixtures the share of the NO formation routes depended very much on the values of rate parameters, when varied within the uncertainty limits of kinetic data evaluations.


91      T. Nagy, T. Turányi
            Reduction of very large reaction mechanisms
using methods based on simulation error minimization
            
Combustion and Flame, 156,  417–428 (2009)

A new species reduction method called the Simulation Error Minimization Connectivity Method (SEM-CM) was developed. According to the SEM-CM algorithm, a mechanism building procedure is started from the important species. Strongly connected sets of species, identified on the basis of the normalized Jacobian, are added and several consistent mechanisms are produced. The combustion model is simulated with each of these mechanisms and the mechanism causing the smallest error (i.e. deviation from the model that uses the full mechanism), considering the important species only, is selected. Then, in several steps other strongly connected sets of species are added, the size of the mechanism is gradually increased and the procedure is terminated when the error becomes smaller than the required threshold. A new method for the elimination of redundant reactions is also presented, which is called the Principal Component Analysis of Matrix F with Simulation Error Minimization (SEM-PCAF). According to this method, several reduced mechanisms are produced by using various PCAF-thresholds. The reduced mechanism having the least CPU time requirement among the ones having almost the smallest error is selected. Application of SEM-CM and SEM-PCAF together provides a very efficient way to eliminate redundant species and reactions from large mechanisms. The suggested approach was tested on a mechanism containing 6874 irreversible reactions of 345 species that describes methane partial oxidation to high conversion. The aim is to accurately reproduce the concentration-time profiles of 12 major species with less than 5% error at the conditions of an industrial application. The reduced mechanism consists of 246 reactions of 47 species and its simulation is 116 times faster than using the full mechanism. The SEM-CM was found to be more effective than the classic Connectivity Method, and also than the DRG, two-stage DRG, DRGASA, basic DRGEP and extended DRGEP methods.
92    T. Nagy, T. Turányi
        Relaxation of concentration perturbation in chemical kinetic systems
        Reaction Kinetics and Catalysis Letters96, 269−278 (2009)

In a linear approximation, the relaxation of a concentration perturbation can be described by a matrix exponen-tial, which can be evaluated using Jordan decomposition. In time-scale analysis this approach has advantages when the Jacobian has degenerate eigenvalues, which may occur when the mechanism contains identical rate constants, characteristic to tropospheric chemistry and low-temperature combustion.


93    I. Lagzi, T. Turányi, R. Lovas
        Development of a grid enabled chemistry application
        Int. J. Computational Science and Engineering4, 195-203 (2009)

P-GRADE development and run-time environment provides high-level graphical support to develop scientific applications and to execute them efficiently on various platforms. This paper gives an overview on the parallelisation of two simulator algorithms; for chemical reaction-diffusion systems and for accidental release of chemical (or radioactive) substances. Applying the same user environment we present our experiences regarding the execution of these chemistry applications on dedicated and non-dedicated clusters, and in different grid environments.



94    T. Kovács, T. Turányi 
         Chemical reactions in the Titan's troposphere during lightning
         Icarus, 207, 938–947(2010)

In the lower troposphere of the Titan the temperature is about 90 K, therefore the chemical production of compounds in the CH4/N2 atmosphere is extremely slow. However, atmospheric electricity could provide conditions at which chemical reactions are fast. This paper is based on the assumption that there are lightning discharges in the Titan's lower atmosphere. The temporal temperature profile of a gas parcel after lightning was calculated at the conditions of 10 km above the Titan's surface. Using this temperature profile, composition of the after-lightning atmosphere was simulated using a detailed chemical kinetic mechanism consisting of 1829 reactions of 185 species. The main reaction paths leading to the products were investigated. The main products of lighting discharges in the Titan's atmosphere are H2, HCN, C2N2, C2H2, C2H4, C2H6, NH3 and H2CN. The annual production of these compounds was estimated in the Titan's atmosphere.


95    T. Kovács, T. Turányi, J. Szépvölgyi
        CCl4 decomposition in RF thermal plasma in inert and oxidative environments
        Plasma Chemistry and Plasma Processing, , 30, 281-286 (2010)

The decomposition of carbon tetrachloride was investigated in an RF inductively coupled thermal plasma reactor in inert CCl4–Ar and in oxidative CCl4–O2–Ar systems, respectively.
The exhaust gases were analyzed by gas chromatography-mass spectrometry. The kinetics of CCl4 decomposition at the experimental conditions was modeled in the temperature range of
300–7000 K. The simulations predicted 67.0% and 97.9% net conversions of CCl4 for CCl4–Ar and for CCl4–O2–Ar, respectively. These values are close to the experimentally determined values of 60.6% and 92.5%. We concluded that in RF thermal plasma much less CCl4 reconstructed in oxidative environment than in an oxygen-free mixture.

96    Turányi Tamás
        Reakciómechanizmusok vizsgálata
        Akadémiai Kiadó, Budapest, 2010

A legtöbb kémiai reakció sok reakciólépésből áll. A reakciómechanizmusok megadják ennek a több száz vagy akár több ezer reakciólépésnek a kémiai egyenletét és sebességét. Az égések reakciómechanizmusainak felhasználásával javítani lehet az erőművek és az autómotorok hatásfokát, és csökkenteni lehet szennyezőanyag kibocsátásukat. A légkörkémiai folyamatokat leíró mechanizmusok segítségével több napra előrejelezhető a várható levegőminőség. A biokémiai folyamatok reakciókinetikai modellezése új utakat nyit meg hatékony gyógyszerek kifejlesztéséhez. A reakciómechanizmusok kinetikai analízise alapján megadható, hogy adott körülmények között melyek a legfontosabb reakcióutak, és hogy milyen kölcsönhatás van az egyes részfolyamatok között. Kiszámítható, hogy egy részletes reakciómechanizmuson alapuló szimulációs modell eredményének mekkora a bizonytalansága a paraméterek bizonytalanságának következtében. Sok módszer ismert nagy reakciómechanizmusok redukciójára, azaz átalakításukra kisebb mechanizmusokká. A könyv összefoglalja az összetett reakciómechanizmusok vizsgálatának különböző módszereit. Célja az, hogy segítse a magyar egyetemi hallgatók reakciókinetikai tanulmányait, illetve hogy gyors tájékozódást nyújtson azoknak a magyar kutatóknak, akik munkájuk során reakciómechanizmusokat használnak és értelmeznek.


97    T. Nagy, T. Turányi
              Uncertainty analysis of varying temperature chemical kinetic systems
              Procedia Social and Behavioral Sciences, 2, 7757–7758 (2010)

All uncertainty analysis studies carried out so far on chemical kinetic systems assumed that the uncertainties of the rate coefficients are independent of temperature, which leads to wrong results in varying temperature systems. Most chemical kinetic databases provide the recommended values of the Arrhenius parameters, the temperature range of validity and the temperature dependence of the uncertainty of rate coefficient k. A method is presented for the transformation of the uncertainty of k to the joint probability density function of the Arrhenius parameters, which is needed for a realistic uncertainty analysis in varying temperature chemical kinetic systems. Recommendations are given for an improved representation of the uncertainty information in future chemical kinetic databases.       




98    T. Nagy, T. Turányi
              Uncertainty of Arrhenius parameters
               Int.J.Chem.Kinet., 43, 359–378(2011)

Chemical kinetics databases for many elementary gas-phase reactions provide the recommended values of the Arrhenius parameters, the temperature range of their validity, and the temperature dependence of the uncertainty of the rate coefficient k. An analytical expression is derived that describes the temperature dependence of the uncertainty of k as a function of the elements of the covariance matrix of the Arrhenius parameters. Based on this analytical expression, the various descriptions of the temperature dependence of the uncertainty of k used in the combustion, and in the IUPAC and JPL atmospheric chemical
databases are analyzed in detail. Recommendations are given for an improved representation of the uncertainty information in future chemical kinetics databases using the covariance matrix of the Arrhenius parameters. Utilization of the joint uncertainty of the Arrhenius parameters is needed for a correct uncertainty analysis in varying temperature chemical kinetic systems. A method is suggested for the determination of the covariance matrix and the joint probability
density function of the Arrhenius parameters from the present uncertainty information given in the kinetics databases. The method is demonstrated on seven gas kinetic reactions exhibiting different types of uncertainty representation 

       


99    L. Varga, B. Szabó, I.Gy. Zsély, A. Zempléni, T. Turányi
              Numerical investigation of the uncertainty of Arrhenius parameters
              J.Math.Chem., 49, 1798-1809 (2011)

The temperature dependence of rate coefficient k is usually described by the Arrhenius expression ln k = ln A - (E/R) T-1. Chemical kinetics databases contain the recommended values of Arrhenius parameters A and E, the uncertainty parameter f(T) of the rate coefficient and temperature range of validity of this information. Taking ln k as a random variable with known normal distribution at two temperatures, the corresponding uncertainty of ln k at other temperatures was calculated. An algorithm is provided for the generation of the histogram of the transformed Arrhenius parameters ln A and E/R, which is in accordance with their 2D normal probability density function (pdf). The upper and the lower edges of the 1D normal distribution of ln k correspond to the two opposite edge regions of the 2D pdf of the transformed Arrhenius parameters. Changing the temperature, these edge regions move around the 2D cone. The rate parameters and uncertainty data belonging to reactions H+H2O2=HO2+H2 and O+HO2=OH+O2 were used as examples.




100   T. Nagy, T. Turányi
              Determination of the uncertainty domain of the Arrhenius parameters needed for the investigation of combustion kinetic models
              Reliability Engineering and System Safety, 107, 29–34 (2012)

Many articles have been published on the uncertainty analysis of high temperature gas kinetic systems that are based on detailed reaction mechanisms. In all these articles a temperature independent relative uncertainty of the rate coefficient is assumed, although the chemical kinetics databases suggest temperature dependent uncertainty factors for most of the reactions. The temperature dependence of the rate coefficient is usually parameterized by the Arrhenius equation. An analytical expression is derived that describes the temperature dependence of the uncertainty of the rate coefficient as a function of the elements of the covariance matrix of the Arrhenius parameters. Utilization of the joint uncertainty of the Arrhenius parameters is needed for a correct uncertainty analysis in varying temperature chemical kinetic systems. The covariance matrix of the Arrhenius parameters, the lower and upper bounds for the rate coefficient, and the temperature interval of validity together define a truncated multivariate normal distribution of the transformed Arrhenius parameters. Determination of the covariance matrix and the joint probability density function of the Arrhenius parameters is demonstrated on the examples of two gas-phase elementary reactions.



101   I. Sedyó, T. Nagy, I. Zsély, T. Turányi, T
              Uncertainty of the Arrhenius parameters of important elementary reactions of the hydrogen-oxygen system
              Proceedings of the ECM, Paper 163, 2011

For several important elementary reactions of the H/O system, all available k measurements and theoretical
determinations were plotted; kmin(T) and kmax(T) limits were determined within a range of temperature. These k limits
were used to obtain temperature dependent uncertainty parameter f(T) and to determine the covariance matrix of the
Arrhenius parameters. The procedure was carried out for reactions H+O2+M=HO2+M, HO2+H=H2+O2,
OH+H2=H2O+H, H+O2=O+OH, O+H2=H+OH, H2O2+H=H2+HO2, OH+OH=H2O+O and H+HO2=OH+OH.



102   T. Varga, I. Zsély, T. Turányi
              Collaborative development of reaction mechanisms using PrIMe datafiles
              Proceedings of the ECM, Paper 164, 2011

Detailed reaction mechanisms have to be validated before application. Agreement of the simulation results with
experimental data should be demonstrated at several reaction conditions. The PrIMe database
(http://www.primekinetics.org/) contains data for several hundred combustion experiments. These XML data files
define the experiment and cite the measured values. We have created a computational tool that is able to use the
information content of the PrIMe database and thus may speed up collaborative mechanism development work.



103   J. Danis, T. Turányi
              Sensitivity analysis of bacterial chemotaxis models
              Procedia Computer Science, 7,  233–234(2011)

Chemotaxis is the process, by which cells sense changes in their chemical environment and move towards more
favorable conditions. This process is controlled by signaling pathways, which are relatively simple, but bear several
important features of the ones of higher organisms. Sensitivity analysis of mathematical chemotaxis models of
bacteria Escherichia coli and Bacillus subtilis was carried out and the most important parameters of the signal
transduction cascades were determined. Global and local similarities of the sensitivity−time functions were found.
Groups of parameters were identified in both models and changes of parameters within the same group can
compensate each other to produce exactly the same response of the cell. This means that the parameter values in these
models are not unique. On the other hand, this feature indicates a novel type of robustness of the signaling pathways.



104   T. Turányi, T. Nagy, I. Gy. Zsély, M. Cserháti, T. Varga, B.T. Szabó, I. Sedyó, P. T. Kiss, A. Zempléni, H. J. Curran         
         
     Determination of rate parameters based on both direct and indirect measurements
               Int.J.Chem.Kinet., 44, 284–302(2012)
       
The determination of rate parameters of gas phase elementary reactions is usually based on direct measurements. The rate parameters obtained in many independent direct measurements are then used in reaction mechanisms, which are tested against the results of indirect experiments, like time-to-ignition or laminar flame velocity measurements. We suggest a new approach that takes into account both direct and indirect measurements and optimizes all influential rate parameters. First, the domain of feasibility of the Arrhenius parameters is determined from all of the available direct measurements. Thereafter, the optimal Arrhenius parameters are sought within this domain to reproduce the selected direct and indirect measurements. Other parameters of a complex mechanism (third body efficiencies, enthalpies-of-formation, parameters of pressure dependence etc.) can also be taken into account in a similar way. A new fitting algorithm and a new method for error calculation were developed to determine the optimal mean values and the covariance matrix of all parameters. The approach is demonstrated on the calculation of Arrhenius parameters of reactions R1: H + O2 = OH + O and R2: H + O2 + M = HO2 + M (low-pressure limit, M= N2 or Ar). In total, 9 direct measurements for reaction R1 (745 data points), 10 direct measurements for reaction R2 (258 data points), and 11 ignition time measurements (79 data points) were taken into account. The application of the method resulted in the following rate parameters for the investigated reactions: R1: A = 3.003x1010 cm3 mol-1 s-1, n = 0.965, E/R = 6158 K (T = 950-3550 K) and R2: A = 7.856x1018 cm6 mol-2 s-1, n = -1.100, E/R = 0 K (low pressure limit, M = N2, T = 300-1850 K). The optimized third body efficiency of Ar relative to N2 is m=0.494 (standard deviation s=0.010). The uncertainty parameter f as a function of temperature was also calculated. Average uncertainty parameter values are f = 0.025 and f = 0.049 for reactions R1 and R2 (corresponding to 6% and 12%), respectively, which are much lower than those of the previous evaluations.



105  I. Gy. Zsély, T. Varga, T. Nagy, M. Cserháti, T. Turányi, S. Peukert, M. Braun-Unkhoff, C. Naumann, U. Riedel
             Determination of rate parameters of cyclohexane and 1-hexene decomposition reactions
             Energy43 , 85-93(2012) 
       
Peukert et al. recently published (Int. J. Chem. Kinet. 2010; 43: 107-119) the results of a series of shock tube measurements on the thermal decomposition of cyclohexane (c-C6H12) and 1-hexene (1-C6H12). The experimental data included 16 and 23 series, respectively, of H-atom profiles measured behind reflected shock waves by applying the ARAS technique (temperature range 1250–1550 K, pressure range 1.48–2.13 bar).
Sensitivity analysis carried out at the experimental conditions revealed that the rate coefficients of the following six reactions have a high influence on the simulated H-atom profiles: R1: c-C6H12 = 1-C6H12, R2: 1-C6H12 = C3H5 + C3H7, R4: C3H5 = aC3H4 + H; R5: C3H7 = C2H4 + CH3; R6: C3H7 = C3H6 + H; R8: C3H5 + H = C3H6. The measured data of Peukert et al. were re-analysed together with the measurement results of Fernandes et al. (J. Phys. Chem. A 2005; 109: 1063-1070) for the rate coefficient of reaction R4, the decomposition of allyl radicals. The optimization resulted in the following Arrhenius parameters: R1: A= 2.441×1019, E/R= 52820; R2: A= 3.539×1018, E/R= 42499; R4: A= 8.563×1019, n= –3.665, E/R= 13825 (high pressure limit); R4: A= 7.676×1031 n= –3.120, E/R= 40323 (low pressure limit); R5: A= 3.600×1012, E/R= 10699; R6: A= 1.248×1017, E/R= 28538; R8: A= 6,212×1013, E/R= –970. The rate parameters above are in cm3, mol, s, and K units. Data analysis resulted in the covariance matrix of all these parameters. The standard deviations of the rate coefficients were converted to temperature dependent uncertainty parameter f(T). These uncertainty parameters were typically f = 0.1 for reaction R1, f = 0.1–0.3 for reaction R2, below 0.5 for reaction R8 in the temperature range of 1250–1380K, and above 1 for reactions R4, R5, and R6.




106   T. Turányi, Z. Tóth
         Hungarian university students’ misunderstandings in thermodynamics and chemical kinetics
         Chemistry Education Research and Practice, 14, 105-116(2013) 

The misunderstandings related to thermodynamics (including chemical equilibrium) and chemical kinetics of first and second year Hungarian students of chemistry, environmental science, biology and pharmacy were investigated. We demonstrated that Hungarian university students have similar misunderstandings in physical chemistry to those reported in published research papers. We also found that there are significant differences between the misunderstandings in physical chemistry of the students who have had very different levels of chemistry studies at the university. However, there is no significant difference between the four students’ groups in misunderstandings brought from the secondary education. Behind the students’ misunderstandings found in this survey there are some common reasons, like using everyday analogy in solving scientific problems, assuming macroscopic properties at particulate level, reducing proportionality to direct proportionality, and mixing the concepts of thermodynamics and reaction kinetics.




107   T. Turányi
         Cell Cycle Models, Sensitivity Analysis
         Encyclopedia of Systems Biology, (editors in chief: Werner Dubitzky, Olaf Wolkenhauer, Kwang-Hyun Cho, Hiroki Yokota)
         Springer, 2013



108   Bazsó G., Góbi S. Magyarfalvi G., Zügner G., Demeter A., Turányi T., Dóbé S., Tarczay Gy.
         Az ELTE TTK Lézerlaboratóriuma: Első eredmények és kutatási perspektívák
         Magyar Kémiai Folyóirat, 118, 65-71(2012) 
        
The Laser Facility at the Science Faculty of Eötvös Loránd University: First Results and Perspectives

In this communication we present the capabilities of the recently founded laser laboratory at the Science Faculty of ELTE. The aims were to start a modern, flexible and extensible facility for photochemistry, spectroscopy and chemical kinetics research and education. The Faculty has spent about 125 million Hungarian forints (~420 thousand euros) on new instruments and on their placement. The value and potential of the laboratory is greatly enhanced by the cooperation with the Institute of Materials and Environmental Chemistry of the Hungarian Academy of Sciences (HAS). A joint laboratory (Environmental Chemical Physics Laboratory) was formed and the partners have placed instruments at the laboratory thus sharing lasers, instruments and expertise. The centerpieces of the laboratory are two high-energy pulsed ns Nd:YAG lasers. The frequency doubled or tripled output of these lasers pump a tunable optical parametric oscillator (OPO) and a high-resolution dye laser or can directly be used for photolysis. A nanosecond excimer laser is also available. From the detectors an intensified CCD camera is worth mentioning. Many other necessary pieces of instrumentation were purchased (monochromator, photon multiplier, digital oscilloscope, electronic amplifier, high vacuum system, molecular jet, optical elements) and contributed by the partners (further monochromators, Xe lamps, high voltage power sources, infrared spectrometer, matrix isolation setup).





109   Turányi T, Zsély I.Gy., Nagy T, Varga T., Pálvölgyi R.
         Reakciósebességi paraméterek meghatározása közvetlen és közvetett mérések együttes felhasználásával
         Magyar Kémiai Folyóirat118, 129-136(2012)  

Utilization of direct and indirect measurements together for the determination of rate parameters

The chemical kinetic measurements can be categorised as direct and indirect ones. In direct measurements, the reaction conditions are selected in such a way that the measured signal depends mainly on the rate parameters of a single reaction step, thus a rate coefficient can be determined from it directly. In the indirect measurements, the experimental results depend on the rate parameters of several elementary reactions and these data can be interpreted via simulations using a reaction mechanism. Assignation of rate parameters of detailed reaction mechanisms is usually based on direct kinetic measurements and the performance of the mechanism is checked on the basis of the results of indirect measurements. However, the rate coefficients determined in direct measurements have large uncertainty (typically factor of 1.3 to 3.0), usually the first version of a detailed reaction mechanism do not reproduce the indirect measurements. Therefore, most published mechanisms contain tuned rate parameters that were selected almost arbitrarily. In an alternative approach, developed and applied by Frenklach et al. and Wang et al., the values of the most critical rate parameters are determined on the basis of selected indirect measurements.
A new method was suggested recently by our Laboratory that consists of the following main steps.
(i) Indirect measurements belonging to the chemical system to be investigated are selected.
(ii) The sensitivities of the simulated values corresponding to the measured signal in the indirect experiments with respect to the rate parameters are calculated. This sensitivity analysis allows the identification of the rate parameters to be optimized. Experimental rate coefficient values determined in direct experiments belonging to the highly sensitive reactions are collected.
(iii) The domain of uncertainty of the rate parameters is determined via a literature review. For the Arrhenius parameters, this determination is based on the relation between the temperature dependent uncertainty of the rate coefficient and the temperature independent uncertainty of the corresponding Arrhenius parameters.
(iv) The optimized values of the rate parameters of the selected elementary reactions within their domain of uncertainty are determined using a newly developed global nonlinear fitting procedure. The optimized rate parameters may include not only Arrhenius parameters, but also third-body efficiencies, enthalpies-of-formation, parameters of pressure dependence, etc.
(v) The covariance matrix of all fitted parameters is calculated. This covariance matrix is transformed to the uncertainty parameter f for each important reaction. Application of uncertainty parameter f is traditional for the characterization of the temperature dependence of the uncertainty of a rate coefficient in gas kinetics.




110    I.Gy. Zsély, C. Olm, R. Pálvölgyi, T. Varga, T. Nagy, T. Turányi
          Comparison of the performance of several recent hydrogen combustion mechanisms
          Proceedings of the ECM, Paper XXX, 2013

A large set of experimental data was collected for hydrogen combustion: ignition measurements in shock tubes (786 data points in 54 datasets) and rapid compression machines (166 data points in 9 datasets), flame velocity measurements (631 data points in 71 datasets) and concentration–time profiles in jet-stirred reactors (152 data points in 9 datasets), covering wide regions of temperature, pressure and equivalence ratio. The performance of 19 recently published hydrogen combustion mechanisms were tested against these experimental data and the dependence of accuracy on the types of experiment and the experimental conditions was investigated.



111   C. Olm, I. Gy. Zsély, T. Varga, T. Nagy, T. Turányi
          Comparison of the performance of several recent wet CO combustion mechanisms
          Proceedings of the ECM, Paper XXX, 2013

A large set of experimental data was collected for wet CO combustion: ignition measurements in shock tubes (532 data points in 50 datasets) and rapid compression machines (444 data points in 46 datasets), flame velocity measurements (1711 data points in 175 datasets) and concentration–time profiles in jet-stirred reactors (54 data points in 9 datasets), covering wide ranges of temperature, pressure, CO/H2 ratio and equivalence ratio. The performance of 15 recently published wet CO combustion mechanisms was tested against these experimental data. The dependence of simulation accuracy on the type of experiment and the error of reproduction of flame velocity measurements at the various experimental conditions was investigated.



112   T. Nagy, C. Olm, I. Gy. Zsély, T. Varga, R. Pálvölgyi, É. Valkó, G. Vincze, T. Turányi
          Optimisation of a hydrogen combustion mechanism
          Proceedings of the ECM, Paper XXX, 2013

A large set of experimental data was collected for hydrogen combustion and used for the optimisation of a hydrogen combustion mechanism: ignition measurements in shock tubes (786 data points in 54 datasets) and rapid compression machines (166 data points in 9 datasets), and concentration–time profiles in jet-stirred reactors (152 data points in 9 datasets), covering wide ranges of temperature, pressure and equivalence ratio. The rate parameters to be optimised were determined by local sensitivity analysis at the conditions of the experiments. Using a global optimisation method, Arrhenius parameters of 8 reactions and the third body efficiency of Ar in the H + O2 + M = HO2 + M reaction were determined. The obtained mechanism reproduces the experimental data better (including the flame velocity measurements; 631 data points in 71 datasets) than the other recent hydrogen combustion mechanisms.




113   A.S. Tomlin, T. Turányi 
          Investigation and improvement of reaction mechanisms using sensitivity analysis and optimization
          Chapter 16 in: Development of detailed chemical kinetic models for cleaner combustion
          editors: F. Battin-Leclerc, E. Blurock, J. Simmie
          Springer, Heidelberg, 2013
   
The Chapter will describe a range of mathematical tools for model sensitivity and uncertainty analysis which may assist in the evaluation of large combustion mechanisms. The aim of such methods is to determine key model input parameters that drive the uncertainty in predicted model outputs. Approaches based on linear sensitivity, linear uncertainty and global uncertainty analysis will be described as well as examples of their application to chemical kinetic modelling in combustion. Improving the robustness of model predictions depends on reducing the extent of uncertainty within the input parameters. This can be achieved via a variety of methods including measurements and theoretical calculations. Optimization techniques which bring together wide sources of data can assist in further constraining the input parameters of a model and therefore reducing the overall model uncertainty. Such methods and their recent application to several combustion mechanisms will be described here.



114      A.S. Tomlin, T. Turányi 
          Mechanism reduction to skeletal form and species lumping
          Chapter 17 in: Development of detailed chemical kinetic models for cleaner combustion
          editors: F. Battin-Leclerc, E. Blurock, J. Simmie
          Springer, Heidelberg, 2013

The numerical simulation of practical combustion devices such as engines and gas turbines requires the coupling of descriptions of complex physical flows with complex chemistry in order to accurately predict phenomena such as ignition and flame propagation. For three dimensional simulations this becomes computationally challenging where interactions between large numbers of chemical species are involved. Historically therefore such simulations used highly simplified descriptions of chemistry which limited the applicability of the models. More recently however, a range of techniques for reducing the size of chemical schemes have been developed, where the resulting reduced schemes can be shown to have accuracies which are almost as good as much larger comprehensive mechanisms. Such techniques will be described in this chapter. Skeletal reduction techniques are first introduced which aim to identify redundant species and reactions within a mechanism over wide ranges of conditions. Approaches based on sensitivity analysis, optimization and direct relation graphs are introduced. Lumping techniques are then discussed which exploit similarities between the structure and reactivity of species in describing lumped components which can represent the sum of several isomers of a particular hydrocarbon species for example. Both approaches can lead to a substantial reduction in the size of chemical mechanisms (numbers of species and reactions) without having a significant impact on model accuracy. They are combined in the chemistry guided reduction approach which is shown to generate reduced chemical schemes which are small enough be used within simulations of ignition behaviour in a homogeneous charge compression ignition (HCCI) engine.


115       T. Turányi, A.S. Tomlin 
          Storage of chemical kinetic information
          Chapter 19 in: Development of detailed chemical kinetic models for cleaner combustion
          editors: F. Battin-Leclerc, E. Blurock, J. Simmie
          Springer, Heidelberg, 2013

This chapter describes various methods for storing chemical kinetic mechanistic information within combustion models. The most obvious way is the definition of the kinetic system of differential equations by a detailed reaction mechanism. Parameterisation of such reaction mechanisms is commented upon here. Another possible approach is to store the solution of the system of ordinary or partial differential equations that defines the model within look-up tables. Such data can then be “retrieved” during combustion simulations within complex reacting flow models instead of solving the kinetic system of differential equations, often at much lower computational cost. Several such methods for storage and retrieval are reviewed here. As an alternative approach, functional representations of the time dependant kinetic changes or the look-up table contents can be achieved, using for example polynomial functions or artificial neural networks and these are also discussed.



116    B. Könnyű, S. K. Sadiq, T. Turányi, R. Hírmondó, B. Müller, H-G Kräusslich, P. V. Coveney, V. Müller
          Gag-Pol Processing during HIV-1 Virion Maturation: a Systems Biology Approach           
          PLoS Comput. Biol., 9(6): e1003103. doi:10.1371/journal.pcbi.1003103

Proteolytic processing of Gag and Gag-Pol polyproteins by the viral protease (PR) is crucial for the production of infectious HIV-1, and inhibitors of the viral PR are an integral part of current antiretroviral therapy. The process has several layers of complexity (multiple cleavage sites and substrates; multiple enzyme forms; PR auto-processing), which calls for a systems level approach to identify key vulnerabilities and optimal treatment strategies. Here we present the first full reaction kinetics model of proteolytic processing by HIV-1 PR, taking into account all canonical cleavage sites within Gag and Gag-Pol, intermediate products and enzyme forms, enzyme dimerization, the initial auto-cleavage of full-length Gag-Pol as well as self-cleavage of PR. The model allows us to identify the rate limiting step of virion maturation and the parameters with the strongest effect on maturation kinetics. Using the modelling framework, we predict interactions and compensatory potential between individual cleavage rates and drugs, characterize the time course of the process, explain the steep dose response curves associated with PR inhibitors and gain new insights into drug action. While the results of the model are subject to limitations arising from the simplifying assumptions used and from the uncertainties in the parameter estimates, the developed framework provides an extendable open-access platform to incorporate new data and hypotheses in the future.


118   T. Varga, I. Gy. Zsély, T. Turányi, T. Bentz, M. Olzmann
         Kinetic analysis of ethyl iodide pyrolysis based on shock tube measurements
         Int.J.Chem.Kinet.46, 295–304 (2014)

The optimization of a kinetic mechanism of the pyrolysis of ethyl iodide was carried out based on data obtained from reflected shock wave experiments with H-ARAS and I-ARAS detection. The analysis took into account also the measurements of Michael et al. (Chem. Phys. Lett. 2000, 319, 99-106) and Vasileiadis and Benson (Int. J. Chem. Kinet. 1997, 29, 915-925) of the reaction H2 + I = H + HI. The following Arrhenius parameters were determined for the temperature range  950 K – 1400 K and the pressure range  1 bar – 2 bar: C2H5I → C2H5 + I: log10(A)= 13.53, E/R= 24472 K; C2H5I → C2H4 + HI: log10(A)= 13.67, E/R= 27168 K; H + HI → H2 + I: log10(A)= 13.82, E/R= 491 K; C2H5I + H →C2H5 + HI: log10(A)= 15.00, E/R= 2593 K (the units of A are cm3, mol, s). The joint covariance matrix of the optimized Arrhenius parameters was also determined. This covariance matrix was converted to the temperature-dependent uncertainty parameters f of the rate coefficients and also to the temperature-dependent correlation coefficients between pairs of rate coefficients. Each fitted rate coefficient was determined with much lower uncertainty compared to the estimated uncertainty of the data available in the literature.


119   C. Olm, I. Gy. Zsély, R. Pálvölgyi, T. Varga, T. Nagy, H. J. Curran, T. Turányi
         Comparison of the performance of several recent hydrogen combustion mechanisms
         Combust. Flame
161, 2219-2234 (2014)
       
A large set of experimental data was accumulated for hydrogen combustion: ignition measurements in shock tubes (770 data points in 53 datasets) and rapid compression machines (229/20), concentration–time profiles in flow reactors (389/17), outlet concentrations in jet-stirred reactors (152/9) and flame velocity measurements (631/73) covering wide ranges of temperature, pressure and equivalence ratio. The performance of 19 recently published hydrogen combustion mechanisms was tested against these experimental data, and the dependence of accuracy on the types of experiment and the experimental conditions was investigated. The best mechanism for the reproduction of ignition delay times and flame velocities is Kéromnčs-2013, while jet-stirred reactor (JSR) experiments and flow reactor profiles are reproduced best by GRI3.0-1999 and Starik-2009, respectively. According to the reproduction of all experimental data, the Kéromnčs-2013 mechanism is currently the best, but the mechanisms NUIG-NGM-2010, ÓConaire-2004, Konnov-2008 and Li-2007 have similarly good overall performances. Several clear trends were found when the performance of the best mechanisms was investigated in various categories of experimental data. Low-temperature ignition delay times measured in shock tubes (below 1000 K) and in RCMs (below 960 K) could not be well-predicted. The accuracy of the reproduction of an ignition delay time did not change significantly with pressure and equivalence ratio. Measured H2 and O2 concentrations in JSRs could be better reproduced than the corresponding H2O profiles. Large differences were found between the mechanisms in their capability to predict flow reactor data. The reproduction of the measured laminar flame velocities improved with increasing pressure and total diluent concentration, and with decreasing equivalence ratio. Reproduction of the flame velocities measured using the flame cone method, the outwardly propagating spherical flame method, the counterflow twin-flame technique, and the heat flux burner method improved in this order. Flame cone method data were especially poorly reproduced. The investigation of the correlation of the simulation results revealed similarities of mechanisms that were published by the same research groups. Also, simulation results calculated by the best-performing mechanisms are more strongly correlated with each other than those of the weakly performing ones, indicating a convergence of mechanism development. An analysis of sensitivity coefficients was carried out to identify reactions and ranges of conditions that require more attention in future development of hydrogen combustion models. The influence of poorly reproduced experiments on the overall performance was also investigated.



120  T. Varga, T. Nagy, C. Olm, I.Gy. Zsély, R. Pálvölgyi, É. Valkó, G. Vincze, M. Cserháti, H.J. Curran, T. Turányi
         Optimization of a hydrogen combustion mechanism using both direct and indirect measurements
         Proc. Combust. Inst., 
35, 589-596 (2015)

The Kéromnčs et al. (2013) mechanism for hydrogen combustion has been optimized using a large set of indirect experimental data, consisting of ignition measurements in shock tubes (566 datapoints in 43 datasets) and rapid compression machines (219/19), and flame velocity measurements (364/59), covering wide ranges of temperature (800 K - 2300 K), pressure (0.1 bar - 65 bar) and equivalence ratio (φ = 0.2 - 5.0). According to the sensitivity analysis carried out at each experimental datapoint, 30 Arrhenius parameters and 3 third body collision efficiency parameters of 11 elementary reactions could be optimized using these experimental data. 1749 directly measured rate coefficient values in 56 datasets belonging to the 11 reaction steps were also utilized. Prior uncertainty ranges of the rate coefficients were determined from literature data. Mechanism optimization has led to a new hydrogen combustion mechanism, a set of newly recommended rate parameters with their covariance matrix, and temperature-dependent posterior uncertainty ranges of the rate coefficients. The optimized mechanism generated here was tested together with 13 recent hydrogen combustion mechanisms and proved to be the best one.


121   T. Turányi, A. S. Tomlin
         Analysis of kinetic reaction mechanisms
         
Springer, 2014

Chemical processes in many fields of science and technology, including combustion, atmospheric chemistry, environmental modelling, process engineering, and systems biology, can be described by detailed reaction mechanisms consisting of numerous reaction steps. This book describes methods that are applicable in all these fields. Topics addressed include: how sensitivity and uncertainty analyses allow the calculation of the overall uncertainty of simulation results and the identification of the most important input parameters, the ways in which mechanisms can be reduced without losing important kinetic and dynamic detail, and the application of reduced models for more accurate engineering optimizations. This monograph is invaluable for researchers and engineers dealing with detailed reaction mechanisms, but is also useful for graduate students of related courses in chemistry, mechanical engineering, energy and environmental science and biology.


122   C. Olm, I. Gy. Zsély, T. Varga, H. J. Curran, T. Turányi
         Comparison of the performance of several recent syngas combustion mechanisms
         Combust. Flame, 162, 1793-1812 (2015)
         
A large set of experimental data was accumulated for syngas combustion: ignition studies in shock tubes (732 data points in 62 datasets) and in rapid compression machines (492/47), flame velocity determinations (2116/217) and species concentration measurements from flow reactors (1104/58), shock tubes (436/21) and jet-stirred reactors (90/3). In total, 4970 data points in 408 datasets from 52 publications were collected covering wide ranges of temperature T, pressure p, equivalence ratio φ, CO/H2 ratio and diluent concentration Xdil. 16 recent syngas combustion mechanisms were tested against these experimental data, and the dependence of their predictions on the types of experiment and the experimental conditions was investigated. Several clear trends were found. Ignition delay times measured in rapid compression machines (RCM) and in shock tubes (ST) at temperatures below 1000 K could not be well-predicted. Particularly for shock tubes, facility effects at temperatures below 1000 K could not be excluded. The accuracy of the reproduction of ignition delay times did not change significantly with pressure. The agreement of measured and simulated laminar flame velocities is better at low initial (i.e. cold side) temperatures, at fuel-lean conditions, for CO-rich and highly diluted mixtures. The reproduction of the experimental flame velocities is better when these were measured using the heat flux method or the counterflow twin-flame technique, compared to the flame cone method and the outwardly propagating spherical flame approach. With respect to all data used in this comparison, five mechanisms were identified that reproduce the experimental data similarly well. These are the NUIG-NGM-2010, Kéromnčs-2013, Davis-2005, Li-2007 and USC-II-2007 mechanisms, in decreasing order of their overall performance. The influence of poorly reproduced experiments and weighting on the performance of the mechanisms was investigated. Furthermore, an analysis of local sensitivity coefficients was carried out to determine the influence of selected reactions at the given experimental conditions and to identify those reactions that require more attention in future development of syngas combustion models.


123   T. Nagy, É. Valkó, I. Sedyó, I. Gy. Zsély, M. J. Pilling, T. Turányi
         
Uncertainty of the rate parameters of several important elementary reactions of the H2 and syngas combustion systems
         Combust. Flame, 162, 2059-2076 (2015)

Re-evaluation of the temperature-dependent uncertainty parameter f(T) of elementary reactions is proposed by considering all available direct measurements and theoretical calculations. A procedure is presented for making f(T) consistent with the form of the recommended Arrhenius expression. The corresponding uncertainty domain of the transformed Arrhenius parameters (ln A, n, E/R) is convex and centrally symmetric around the mean parameter set. The f(T) function can be stored efficiently using the covariance matrix of the transformed Arrhenius parameters. The calculation of the uncertainty of a backward rate coefficient from the uncertainty of the forward rate coefficient and thermodynamic data is discussed. For many rate coefficients, a large number of experimental and theoretical determinations are available, and a normal distribution can be assumed for the uncertainty of ln k. If little information is available for the rate coefficient, equal probability of the transformed Arrhenius parameters within their domain of uncertainty (i.e. uniform distribution) can be assumed. Algorithms are provided for sampling the transformed Arrhenius parameters with either normal or uniform distributions. A suite of computer codes is presented that allows the straightforward application of these methods. For 22 important elementary reactions of the H2 and syngas (wet CO) combustion systems, the Arrhenius parameters and 3rd body collision efficiencies were collected from experimental, theoretical and review publications. For each elementary reaction, kmin and kmax limits were determined at several temperatures within a defined range of temperature. These rate coefficient limits were used to obtain a consistent uncertainty function f(T) and to calculate the covariance matrix of the transformed Arrhenius parameters.


124  Tamás Varga, Tamás Turányi, Eszter Czinki, Tibor Furtenbacher, Attila G. Császár
        ReSpecTh: a joint reaction kinetics, spectroscopy, and thermodynamics information system
        Proceedings of the European Combustion Meeting – 2015, Paper P1-04, March 30–April 2, 2015, Budapest, Hungary,
        ISBN 978-963-12-1257-0
       
Reaction kinetics, high-resolution molecular spectroscopy, and thermochemistry data are frequently used together to help the interpretation of complex experiments and to carry out simulations of complex gas-phase chemical systems. The relevant systems may involve combustion reactions, and atmospheric, stellar and interstellar environments. The principal aim of the newly set-up active information system ReSpecTh is to provide useful, accurate searchable data and utility programs that can be used in several engineering and scientific fields either separately or simultaneously. The present status of ReSpecTh, set up at http://respecth.hu/, is described. ReSpecTh is under constant development and significant extensions are expected to come regularly.


125  Carsten Olm, Tamás Varga, Éva Valkó, Sandra Hartl, Christian Hasse, Tamás Turányi
        Development of an ethanol combustion mechanism based on a hierarchical optimization approach
        Proceedings of the European Combustion Meeting – 2015, Paper P1-35, March 30–April 2, 2015, Budapest, Hungary,
        ISBN 978-963-12-1257-0
       
A detailed multi-purpose reaction mechanism for ethanol combustion was developed for the use in high-fidelity numerical simulations describing ignition, flame propagation and species concentration profiles with high accuracy. Justified by prior analysis, an optimization of 44 Arrhenius parameters of 14 crucial elementary reactions using several thousand direct and indirect measurement data points was performed, starting from the ethanol combustion mechanism of Saxena and Williams (2007). The final optimized mechanism was compared to 13 reaction mechanisms frequently used in ethanol combustion with respect to their accuracy in reproducing the various types of experimental data.


126   Viktor Samu, Tamás Varga, Tamás Turányi
         Investigation of ethane pyrolysis and oxidation at high pressures using global optimization based on shock tube data
        Proceedings of the European Combustion Meeting – 2015, Paper P1-38, March 30–April 2, 2015, Budapest, Hungary,
        ISBN 978-963-12-1257-0

Tranter et al. conducted a series of experiments of ethane oxidation and pyrolysis covering a wide range of temperature (800 K – 1500 K) and pressure (5 bar – 1000 bar) in a high pressure shock tube. The oxidation and pyrolysis of ethane were carried out behind reflected shock waves, and the concentrations of the reaction products were measured by gas chromatography. The results of these experiments were re-evaluated by optimizing selected rate parameters of the NUIG C5 combustion mechanism. The rate coefficients of 14 reactions were selected based on sensitivity analysis and preliminary uncertainty estimations for optimization. Arrhenius parameters (A, n, E) of the selected reaction steps were optimized using not only the experimental data of Tranter et al., but also the results of direct measurements related to these reactions. The obtained mechanism with the optimized rate parameters described the experiments of Tranter et al. much better than the original mechanism. New rate coefficient recommendations were obtained for all reactions with temperature dependent uncertainties including well studied reactions such as C2H6+OH = C2H5+H2O and less-known reactions like C2H3+O2 = CH2CHO+O.
        

127  Éva Valkó, Alison S. Tomlin, Tamás Varga, Tamás Turányi
        Investigation of the effect of correlated uncertain rate parameters on a model of hydrogen combustion using a generalized HDMR method
        Proceedings of the European Combustion Meeting – 2015, Paper P1-39, March 30–April 2, 2015, Budapest, Hungary,
        ISBN 978-963-12-1257-0
       
The High Dimensional Model Representation (HDMR) method has been applied in several previous studies to obtain global sensitivity indices of uncorrelated model parameters in combustion systems. The method is based on a decomposition of the model output in terms of a hierarchy of cooperative effects among the model inputs, which is unique when the input parameters are independent. However, many combustion systems will contain correlated input parameters. The development of a generalized HDMR method is therefore presented here, which uses the Rosenblatt transformation on a correlated model parameter sample to obtain a sample of independent parameters. The generalized HDMR method is used for the determination of sensitivity indices of a hydrogen combustion model with 33 correlated input parameters for a given set of experimental conditions. The effect of the correlation of rate parameters on the calculated sensitivity indices of ignition delay times is investigated.


128  Róbert Pálvölgyi, Tamás Varga, Tamás Turányi
        Investigations of available experimental and modeling data on the oxidative coupling and partial oxidation of methane
        Proceedings of the European Combustion Meeting – 2015, Paper P1-70, March 30–April 2, 2015, Budapest, Hungary,
        ISBN 978-963-12-1257-0
 
Large amount of experimental data, related to measurements of oxidative coupling and partial oxidation of methane in stirred and flow reactors were collected in which distributions of C2 and partially oxygenated products were determined. Several detailed reaction mechanisms published for the description of these processes were also gathered. Some of these mechanisms were developed primarily for the modeling of ultra-rich combustion of methane, while others were developed for a wider range of conditions. Simulations using all these reaction mechanisms were carried out at the conditions of all collected experimental data. A large part of the experimental data could be described well using one or another reaction mechanism. In general, the modern comprehensive mechanisms performed better compared to the specialized mechanisms. However, there is not a single published mechanism that is able to reproduce all these experimental data. Some other experiments reported a slow conversion from methane to oxygenates and higher hydrocarbons, which could not be described by any of the investigated mechanisms. This behavior of the models might indicate a fundamental lack of understanding of the main reaction pathways, or an incomplete description of the physical-chemical phenomena that occur during the experiments (e.g. heat loss, radical recombination at walls). Simple models for taking into account the effect of the reactor wall were investigated, but a good reproduction of these “problematic” experiments could not be achieved.


129  Tamás Turányi
        Analysis of Complex Reaction Schemes
        Elsevier Reference Module in Chemistry, Molecular Sciences and Chemical Engineering, article 11529, 2016
 
Complex kinetic reaction schemes are widely used in many areas of science and technology for computer simulations, but numerical analysis of these schemes may provide further insight. Pathway analysis identifies the key chemical transformations. Sensitivity analysis shows which are the most important parameters, and uncertainty analysis may be used for the assessment of the confidence that can be placed in simulation results. Mechanism reduction methods can produce reduced schemes that provide almost identical simulation results using much less computer time, thus allowing engineering optimizations.


130  T. Varga, C. Olm, T. Nagy, I. Gy. Zsély, É. Valkó, R. Pálvölgyi, H. J. Curran, T. Turányi       
            Development of a joint hydrogen and syngas combustion mechanism based on an optimization approach
            Int.J.Chem.Kinet., 48, 407–422 (2016)

A comprehensive and hierarchical optimization of a joint hydrogen and syngas combustion mechanism has been carried out. The Kéromnčs et al. (2013) mechanism for syngas combustion was updated with our recently optimized hydrogen combustion mechanism (Varga et al. 2015), and optimized using a comprehensive set of direct and indirect experimental data relevant to hydrogen and syngas combustion. The collection of experimental data consisted of ignition measurements in shock tubes and rapid compression machines, burning velocity measurements, and species profiles measured using shock tubes, flow reactors and jet-stirred reactors. The experimental conditions covered wide ranges of temperatures (800 - 2500 K), pressures (0.5 - 50 bar), equivalence ratios (φ = 0.3 - 5.0) and C/H ratios (0 - 3). In total, 48 Arrhenius parameters and 5 third-body collision efficiency parameters of 18 elementary reactions were optimized using these experimental data. A large number of directly measured rate coefficient values belonging to 15 of the reaction steps were also utilized. The optimization has resulted in a H2/CO combustion mechanism which is applicable to a wide range of conditions. Moreover, new recommended rate parameters with their covariance matrix and temperature-dependent uncertainty ranges of the optimized rate coefficients are provided. The optimized mechanism was compared to 19 recent hydrogen and syngas combustion mechanisms and is shown to provide the best reproduction of the experimental data.



131    C. Olm, T. Varga, É. Valkó, S, Hartl, C. Hasse, T. Turányi         
               Development of an ethanol combustion mechanism based on a hierarchical optimization approach        
                Int.J.Chem.Kinet., 48, 423–441 (2016)

A detailed reaction mechanism for ethanol combustion was developed for describing ignition, flame propagation and species concentration profiles with high accuracy. Starting from a modified version of the ethanol combustion mechanism of Saxena and Williams (2007) and adopting the H2/CO base chemistry from the joint optimized hydrogen and syngas combustion mechanism of Varga et al. (2015), an optimization of 54 Arrhenius parameters of 16 important elementary C1/C2 reactions was performed using several thousand direct and indirect measurement data points as well as the results of theoretical determinations of reaction rate coefficients. The final optimized mechanism was compared to 16 reaction mechanisms that have been used for the simulation of ethanol combustion with respect to the accuracy in reproducing the available experimental data, including measurements of ignition delay times in shock tubes (444 data points in 39 datasets) and rapid compression machines (20/3), laminar burning velocity measurements (1011/124), and species profiles measured using flow reactors (1750/23), jet stirred reactors (398/6) and shock tubes (8871/14). In addition to providing best fitted values for 54 Arrhenius parameters, the covariance matrix of the optimized parameters was calculated, which provides a description of the temperature-dependent ranges of uncertainty for each of the optimized rate coefficients.



132    V. Samu, T. Varga, K. Brezinsky, T. Turányi          
                Investigation of ethane pyrolysis and oxidation at high pressures using global optimization based on shock tube data
                Proc. Combust. Inst., 36, 691–698 (2017)
      
Tranter et al. conducted a series of experiments of ethane oxidation and pyrolysis covering a wide range of temperature (800 K – 1500 K) and pressure (40 bar – 1000 bar) in a high pressure shock tube. The reaction products were measured using gas chromatography. The results of these experiments were re-evaluated by optimizing selected rate parameters of the NUIG C5 v49 combustion mechanism updated with a previously optimized H2/CO combustion mechanism. The rate parameters of 14 reactions were selected based on sensitivity analysis and preliminary uncertainty estimations for optimization. Arrhenius parameters (A, n, E) of the selected reaction steps were optimized using not only the experimental data of Tranter et al., but also the results of direct measurements and theoretical determinations related to these reactions. The obtained mechanism with the optimized rate parameters described the experiments of Tranter et al. much better than the original mechanism. New rate coefficient expressions were obtained for the 14 reactions with temperature dependent uncertainties, recommended for the temperature and pressure ranges above.



133    É. Valkó, T. Varga, A.S. Tomlin, T. Turányi
               Investigation of the effect of correlated uncertain rate parameters on a model of hydrogen combustion using a generalized HDMR method
               Proc. Combust. Inst.36, 681-689 (2017)

The High Dimensional Model Representation (HDMR) method has been applied in several previous studies to obtain global sensitivity indices of uncorrelated model parameters in combustion systems. However, the rate parameters of combustion models are intrinsically correlated and therefore uncertainty analysis methods are needed that can handle such parameters. A generalized HDMR method is presented here, which uses the Rosenblatt transformation on a correlated model parameter sample to obtain a sample of independent parameters. The method provides a full set of both correlated and marginal sensitivity indices. Ignition delay times predicted by an optimized hydrogen–air combustion model in stoichiometric mixtures near the three explosion limits are investigated with this new global sensitivity analysis tool. The sensitivity indices which account for all the correlated effects of the rate parameters are shown to dominate uncertainties in the model output. However, these correlated indices mask the individual influence of parameters. The final marginal uncorrelated sensitivity indices for individual parameters better indicate the change of importance of homogeneous gas phase and species wall-loss reactions as the pressure is increased from above the first explosion limit to above the third limit. However, these uncorrelated indices are small and whilst they provide insights into the dominant chemical and physical processes of the model over the range of conditions studied, the correlations between parameters have a very significant effect. The implications of this result on model tuning will be discussed.



134    É. Valkó, T. Varga, A.S. Tomlin, Á. Busai, T. Turányi
          Általánosított HDMR-módszer alkalmazása korrelált bizonytalan paraméterek hatásának vizsgálatára
          Alkalmazott Matematikai Lapok, 33, 139-157 (2016)

A HDMR- (High Dimensional Model Representation) módszert széles körben alkalmazzák korrelálatlan paraméterekkel rendelkező modellek globális érzékenységanalízisére. Egyes modellek esetén azonban a modell paramétereit olyan mérési eredmények alapján határozzák meg, amelyek következtében a paraméterek értékét korreláltan kapjuk meg. A HDMR-módszer egy általánosítását mutatjuk be, amelynek során a Rosenblatt-transzformáció segítségével korrelált paraméterminta alapján független paramétereket állítunk elő. A módszer alkalmazásával kiszámíthatjuk az összes korrelált és feltételes érzékenységi indexet. Az elkészített számítógépes program pontosságát egyszerű lineáris modelleken teszteltük, majd elvégeztük egy optimalizált szintézisgáz-égési modellel számított gyulladási idők érzékenységanalízisét. Az égési modell esetén az érzékenységi eredmények megmutatták a paraméterek közötti korrelációk jelentős hatását, és hogy a korrelációkon keresztül a legtöbb vizsgált paraméternek közel azonos hatása van a modelleredmény szórására. Emellett a feltételes érzékenységi indexek alapján azonosíthatóak azok a paraméterek, amelyek a saját hatásaikon keresztül vannak jelentős befolyással az eredmény szórására, tehát önmagukban is fontos szerepet játszanak az égési folyamat szimulációja során.



135   Cheng Chi, Gábor Janiga, Abouelmagd Abdelsamie Katharina Zahringer, Tamás Turányi, Dominique Thévenin
         DNS study of the optimal chemical markers for heat release in syngas flames
         Flow, Turbulence and Combustion, 98, 1117–1132 (2017)

The purpose of this study is to identify a quantitative marker of the heat release rate (HRR) distribution using experimentally measurable species. Turbulent syngas (CO/H2/air) flames with different equivalence ratios, H2/CO ratios, and turbulence intensities are computed by Direct Numerical Simulations (DNS) in order to obtain an indirect but accurate estimation of heat release profiles. To check the robustness of the estimation, two different kinetic mechanisms have been considered. Based on a direct image analysis of the DNS results, normalized species concentrations combined with exponents are systematically tested in an attempt to reconstruct as accurately as possible the field of heat release rate. A systematic comparison is used to identify the best possible exponents associated with each species combination. Differing from previous studies, the present analysis takes into account the local thickness of the turbulent heat release zone. As a consequence, the obtained optimal species combinations represent not only the position of peak heat release but also local changes in the topology of the reaction zone (thickness, curvature). In the end, the heat release rate of atmospheric syngas flames can, in general, be best approximated using the concentrations of HCO and OH, using f=1.5 (HCO) and f=0.75 (OH) , when considering only species that are measurable by Laser-Induced Fluorescence.



136   Carsten Olm, Tamás Varga, Éva Valkó, Henry J. Curran, Tamás Turányi
         Uncertainty quantification of a newly optimized methanol and formaldehyde combustion mechanism
         Combust. Flame, 186, 45-64 (2017)
  
A detailed reaction mechanism for methanol combustion that is capable of describing ignition, flame propagation and species concentration profiles with high accuracy has been developed. Starting from a modified version of the methanol combustion mechanism of Li et al. (Int. J. Chem. Kinet. 2007) and adopting the H2/CO base chemistry from the joint optimized hydrogen and syngas combustion mechanism of Varga et al. (Int. J. Chem. Kinet., 2016), an optimization of 57 Arrhenius parameters of 17 important elementary reactions was performed, using several thousand indirect measurement data points, as well as direct and theoretical determinations of reaction rate coefficients as optimization targets. The final optimized mechanism was compared to 18 reaction mechanisms published in recent years, with respect to their accuracy in reproducing the available indirect experimental data for methanol and formaldehyde combustion. The utilized indirect measurement data, in total 24,900 data points in 265 datasets, include measurements of ignition delay times, laminar burning velocities and species profiles captured using a variety of experimental techniques. In addition to new best fit values for all rate parameters, the covariance matrix of the optimized parameters, which provides a quantitative description of the temperature-dependent ranges of uncertainty for the optimized rate coefficients, was calculated. These posterior uncertainty limits are much narrower than the prior limits in the temperature range for which experimental data are available. The uncertainty of the self-reaction of HȮ2 radicals and important H-atom abstraction reactions from the methanol molecule are discussed in detail.



137   Viktor Samu; Tamás Varga; Igor Rahinov; Sergey Cheskis; Tamás Turányi
         Determination of rate parameters based on NH2 concentration profiles measured in ammonia-doped methane−air flames
         Fuel, in press (2017)

The experiments of Rahinov et al. (Combust. Flame, 145 (2006) 105-116) measuring NH2 concentration profiles in methane−air laminar flat flames doped with ammonia were re-evaluated. The flames were simulated with the FlameMaster code using a modified NOx combustion mechanism of the CRECK Modeling Group. Based on local sensitivity analysis results, Arrhenius parameters A, n, E of reaction steps NH2+H = NH+H2 and NH3+OH = NH2+H2O were selected for optimization, which took into account not only the experimental data of Rahinov et al., but also related direct measurements and theoretical determinations as optimization targets. The optimized mechanism described the measured concentration profiles better than the original one, while the new rate parameter values were within the prior uncertainty limits obtained from the evaluation of literature data. The optimization process also provided new posterior uncertainty limits, which are within the prior uncertainty limits.




138   É. Valkó, T. Varga, A.S. Tomlin, Á. Busai, T. Turányi
         Investigation of the effect of correlated uncertain rate parameters via the calculation of global and local sensitivity indices
         J. Math.Chem., in press (2017)

Applications of global uncertainty methods for models with correlated parameters are essential to investigate chemical kinetics models. A global sensitivity analysis method is presented that is able to handle correlated parameter sets. It is based on the coupling of the Rosenblatt transformation with an optimized Random Sampling High Dimensional Model Representation (HDMR) method. The accuracy of the computational method was tested on a series of examples where the analytical solution was available. The capabilities of the method were also investigated by exploring the effect of the uncertainty of rate parameters of a syngas-air combustion mechanism on the calculated ignition delay times. Most of the parameters have large correlated sensitivity indices and the correlation between the parameters has a high influence on the results. It was demonstrated that the values of the calculated total correlated and final marginal sensitivity indices are independent of the order of the decorrelation steps. The final marginal sensitivity indices are meaningful for the investigation of the chemical significance of the reaction steps. The parameters belonging to five elementary reactions only, have significant final marginal sensitivity indices. Local sensitivity indices for correlated parameters were defined which are the linear equivalents of the global ones. The results of the global sensitivity analysis were compared with the corresponding results of local sensitivity analysis for the case of the syngas-air combustion system. The same set of reactions was indicated to be important by both approaches.


Tamás Turányi