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Journal articles on the topic 'Chemical equilibrium – Simulation methods'

Author: Grafiati

Published: 4 June 2021

Last updated: 4 February 2022

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1

Tanaka, Y., K. Tomita, Y. Inada, et al. "Non-equilibrium Studies in Switching Arc Plasmas in Japan." PLASMA PHYSICS AND TECHNOLOGY 4, no. 3 (2017): 225–33. http://dx.doi.org/10.14311/ppt.2017.3.225.

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This paper briefly introduce research work examples of non-equilibrium studies in switching arcs. In understanding arc behavior, one often assumes local thermodynamic equilibrium (LTE) condition in the arc plasma. However, actual arc plasmas are not completely and not always in LTE state because of strong temperature change temporally and spatially, and high electric field application etc. Recently, we have a collaboration work in numerical simulations and experimental approaches for decaying arcs without LTE assumption. First, our numerical model is presented for decaying arcs without chemica

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Hu, Yumeng, Haiming Huang, and Zimao Zhang. "Numerical simulation of a hypersonic flow past a blunt body." International Journal of Numerical Methods for Heat & Fluid Flow 27, no. 6 (2017): 1351–64. http://dx.doi.org/10.1108/hff-05-2016-0187.

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Purpose The purpose of this paper is to explore the characteristics of hypersonic flow past a blunt body. Design/methodology/approach The implicit finite volume schemes are derived from axisymmetric Navier–Stokes equations by means of AUSM+ and LU-SGS methods, and programmed in FORTRAN. Based on the verified result that a 2D axisymmetric chemical equilibrium flow has a good agreement with the literature, the characteristics of hypersonic flow past a sphere are simulated by using four different models which involve four factors, namely, viscous, inviscid, equilibrium and calorically perfect gas

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Coates, J. A., and J. J. Delfino. "Sources of Uncertainty in the Application of the Equilibrium Partitioning Approach to Sediment Quality Assessment." Water Science and Technology 28, no. 8-9 (1993): 317–28. http://dx.doi.org/10.2166/wst.1993.0630.

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One widely discussed method to assess biological impact of contaminated sediments is through the application of the equilibrium partitioning model. The partitioning model can be used to develop normalized chemical concentrations that can be correlated to biological effects resulting from sediment contamination. The application of the equilibrium partitioning model requires the measurement or estimation of several model variables. However, the combined uncertainties in the determination of these variables may limit the usefulness of this approach. Uncertainty in estimated pore water effects con

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Khokha, Yu V., M. B. Yakovenko, and O. V. Lyubchak. "Simulation of kerogen evolution by thermodynamic methods (on the example of Southern oil and gas region)." Prospecting and Development of Oil and Gas Fields, no. 3(76) (September 27, 2020): 33–45. http://dx.doi.org/10.31471/1993-9973-2020-3(76)-33-45.

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The article considers the methods for estimating the level of organic matter transformation, scattered in sedimentary strata, in the process of catagenetic transformations. The authors show the efficiency of kerogen property research by coal petrographic methods and palynological analysis, the purpose of which is to establish the paleotemperature that was actualized in the process of evolution. The advantages and disadvantages of establishing the organic matter generation potential by pyrolytic methods, primarily by pyrolysis by Rock-Eval, are evaluated. In the context of the organic matter ev

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Gallis, Michael A., and John K. Harvey. "Modelling of chemical reactions in hypersonic rarefied flow with the direct simulation Monte Carlo method." Journal of Fluid Mechanics 312 (April 10, 1996): 149–72. http://dx.doi.org/10.1017/s0022112096001954.

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In this paper the phenomenon of chemical reactivity in hypersonic rarefied flows is examined. A new model is developed to describe the reactions and post-collision energy exchange processes that take place under conditions of molecular non-equilibrium. The new scheme, which is applied within the framework of the direct simulation Monte Carlo (DSMC) method, draws its inspiration from the principles of maximum entropy which were developed by Levine & Bernstein. Sample hypersonic flow fields, typical of spacecraft re-entry conditions in which reactions play an important role, are presented an

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Chen, Qiu, and Lisha Feng. "Simulation Study of Citronellol-geraniol Rectification Tower Based on Aspen Plus Software." MATEC Web of Conferences 267 (2019): 02008. http://dx.doi.org/10.1051/matecconf/201926702008.

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Aspen Plus is a large-scale chemical simulation software based on steady-state chemical simulation, optimization, sensitivity analysis and economic evaluation. It can analyze the planning, research, development and technical reliability of chemical processes. High-purity citronellol and geraniol, the main high-value components of citronella oil, make the rectification and purification process difficult due to their boiling point and heat sensitivity, with high separation cost and poor effect, resulting in low economic benefits. This paper uses Aspen Plus software to estimate the physical prope

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Nguyen, Van T., D. D. Do, and D. Nicholson. "Reconciliation of different simulation methods in the determination of the equilibrium branch for adsorption in pores." Molecular Simulation 40, no. 7-9 (2014): 713–20. http://dx.doi.org/10.1080/08927022.2013.829229.

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Schwoebel, Stephan Daniel, Dominik Höhlich, Thomas Mehner, and Thomas Lampke. "Stabilization of the Computation of Stability Constants and Species Distributions from Titration Curves." Computation 9, no. 5 (2021): 55. http://dx.doi.org/10.3390/computation9050055.

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Thermodynamic equilibria and concentrations in thermodynamic equilibria are of major importance in chemistry, chemical engineering, physical chemistry, medicine etc. due to a vast spectrum of applications. E.g., concentrations in thermodynamic equilibria play a central role for the estimation of drug delivery, the estimation of produced mass of products of chemical reactions, the estimation of deposited metal during electro plating and many more. Species concentrations in thermodynamic equilibrium are determined by the system of reactions and to the reactions’ associated stability constants. I

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Yakhyaev, M. A., V. S. Gutenkov, and Yu A. Pisarenko. "DEVELOPMENT OF REACTION-RECTIFICATION PROCESS OF OBTAINING MESITYL OXIDE. I. SIMULATION OF KINETICS AND PHASE EQUILIBRIUM IN THE REACTION SYSTEM." Fine Chemical Technologies 13, no. 5 (2018): 5–13. http://dx.doi.org/10.32362/2410-6593-2018-13-5-5-13.

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Mesityl oxide is an important product of organic synthesis, which is used in the manufacture of pharmaceuticals and as a solvent. The demand for mesityl oxide is growing, which determines the need for further improvement of its production. The disadvantages of the traditional methods of obtaining mesityl oxide are low values of reagent conversion and selectivity. To eliminate them, it is proposed to obtain mesityl oxide in a combined reaction-rectification process. The combination of chemical transformation and separation of the resulting reaction mixture by means of rectification in one appar

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Özmen, Haluk, and Akbar Naseriazar. "Effect of simulations enhanced with conceptual change texts on university students’ understanding of chemical equilibrium." Journal of the Serbian Chemical Society 83, no. 1 (2018): 121–37. http://dx.doi.org/10.2298/jsc161222065o.

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The aim of this research was to investigate the effect of computer simulations enhanced with conceptual change texts (CS-CCT) on first year university students? understanding of chemical equilibrium. A quasi-experimental design and one control group (CG, N = 60) as well as one experimental group (EG, N = 65) were used in the study. While students in CG were taught with traditional methods based on textbooks and blackboard, the EG studied the same unit with CS-CCT. The chemical equilibrium concept test (CECT) was administered as pre-test, post-test and delayed test to collect data. The results

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Ohno, Shiho, Noriyoshi Manabe, Takumi Yamaguchi, Jun Uzawa, and Yoshiki Yamaguchi. "Ribitol in Solution Is an Equilibrium of Asymmetric Conformations." Molecules 26, no. 18 (2021): 5471. http://dx.doi.org/10.3390/molecules26185471.

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Ribitol (C5H12O5), an acyclic sugar alcohol, is present on mammalian α-dystroglycan as a component of O-mannose glycan. In this study, we examine the conformation and dynamics of ribitol by database analysis, experiments, and computational methods. Database analysis reveals that the anti-conformation (180°) is populated at the C3–C4 dihedral angle, while the gauche conformation (±60°) is seen at the C2–C3 dihedral angle. Such conformational asymmetry was born out in a solid-state 13C-NMR spectrum of crystalline ribitol, where C1 and C5 signals are unequal. On the other hand, solution 13C-NMR h

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Renane, R., Olivier Serro-Guillaume, A. Nour, and R. Allouche. "Simulation and Analysis of the Structure of Laminar Premixed Flame." Advanced Materials Research 274 (July 2011): 23–32. http://dx.doi.org/10.4028/www.scientific.net/amr.274.23.

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The aim of our work is to contribute to the analysis of the structure of laminar premixed Methane-Air flames using two methods. This allows us to validate the chemical mechanisms, to know the fine structure of the flame front and to get, for a given pressure and temperature of fresh gases, the speed and the mass fractions of all chemical species of the combustion reaction. The first method is based on controlling combustion parameters of laminar premixed flame. The numerical resolution strategy used consist in the discretization of the balance equations completed by the transport properties an

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Hress, Oleksandr Volodimirovich, O. B. Isayev, O. O. Chebotaryova, and Kaiming Wu. "Numerical Simulation of Macrosegregation Impurities in the Solidifying Continuous Casting Steel Billet." Materials Physics and Chemistry 1, no. 1 (2018): 88. http://dx.doi.org/10.18282/mpc.v1i1.570.

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<p>In this study, new theoretical conceptions have been developed about an impurity segregation mechanism at the time of alloy solidification considering present microvolumes with different chemical compositions during alloy solidification. It has been concluded that this conception allows to establish and optimize technologic parameters that influence the production of the main types of macro-heterogeneity. The derived model conceptions have confirmed the final condition of real continuous casting billets by using the advanced analyzing methods. </p><p>Highlights </p>&

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Hečko, Dávid, Pavol Mičko, Michal Holubčík, and Andrej Kapjor. "Experimental Simulation of Hydrate Formation Process in a Circulating Device." Processes 9, no. 9 (2021): 1529. http://dx.doi.org/10.3390/pr9091529.

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This paper focuses on the model of gas hydrate formation in an experimental device, which allows the circulation of the resulting mixture (water and gas) and significantly accelerates the process of hydrate formation in the laboratory. A 3D model was developed to better imagine the placement of individual parts of the device. The kinetics of hydrate formation were predicted from equilibrium values of chemical potentials. The aim of solving the equations of state gases in the mathematical model was to optimize the parameters involved in the formation of hydrates. The prediction of the mathemati

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R. Zohar, Asnat, and Sharona T. Levy. "Attraction vs. repulsion – learning about forces and energy in chemical bonding with the ELI-Chem simulation." Chemistry Education Research and Practice 20, no. 4 (2019): 667–84. http://dx.doi.org/10.1039/c9rp00007k.

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This work seeks to solve one of the basic problems in chemistry learning: understanding the chemical bond as a dynamic equilibrium between attractive and repulsive forces. This force-based model is difficult to grasp, as there are no analogues from everyday life for both attractions and repulsions happening simultaneously. In addition, current teaching approaches often mislead by using mainly the ‘octet rule’ heuristic. As a result, students construct naïve models of the chemical bond, usually viewing atoms as solid balls that are attached to each other in order to “achieve an octet.” To repre

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BELOUAGGADIA, N., H. OLIVIER, and R. BRUN. "Numerical and theoretical study of the shock stand-off distance in non-equilibrium flows." Journal of Fluid Mechanics 607 (June 30, 2008): 167–97. http://dx.doi.org/10.1017/s0022112008001973.

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A theoretical model based on a quasi-one-dimensional formulation is developed which allows determination of the shock stand-off distance at the stagnation point of blunt bodies in hypersonic non-equilibrium flows. Despite the simple ideal dissociating gas model implemented in the theoretical approach, it gives insight into the main physics governing the shock stand-off problem. More detailed and precise data are obtained by a numerical simulation where vibrational and chemical relaxation processes as well as their interactions are taken into account. The physical modelling of these processes i

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Ziegler, U. "A chemistry and cooling module for the NIRVANA code." Astronomy & Astrophysics 620 (December 2018): A81. http://dx.doi.org/10.1051/0004-6361/201834033.

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Context. Gas cooling and other thermal processes in the interstellar medium are intimately related to its chemical evolution. To accurately model chemical processes in large-scale gas-dynamical simulations the usage of existing sophisticated astrochemical networks is presently impossible due to prohibitive computational costs. A viable way to deal with the problem is by the design of reduced chemical networks that satisfactorily reproduce the most important features of the more elaborate networks. Aims. A chemistry and cooling module for the interstellar medium is developed that is realistic f

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Grujicic, Mica, Jennifer Snipes, and S. Ramaswami. "A computational analysis of the utility of chemical reactions within protective structures in mitigating shockwave-impact effects." Multidiscipline Modeling in Materials and Structures 12, no. 3 (2016): 438–72. http://dx.doi.org/10.1108/mmms-04-2015-0019.

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Purpose The purpose of this paper is to introduce and analyze a new blast-wave impact-mitigation concept using advanced computational methods and tools. The concept involves the use of a protective structure consisting of bimolecular reactants displaying a number of critical characteristics, including: a high level of thermodynamic stability under ambient conditions (to ensure a long shelf-life of the protective structure); the capability to undergo fast/large-yield chemical reactions under blast-impact induced shock-loading conditions; large negative activation and reaction volumes to provide

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Fernandes, Fabiano A. N., Francisco E. Linhares-Junior, and Samuel J. M. Cartaxo. "Prediction of Fischer–Tropsch Synthesis Kinetic Parameters Using Neural Networks." Chemical Product and Process Modeling 9, no. 2 (2014): 97–103. http://dx.doi.org/10.1515/cppm-2013-0048.

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Abstract The kinetic mechanism of the Fischer–Tropsch synthesis (FTS) is complex resembling a polymerization reaction. The kinetic rate constants for initiation, propagation and termination steps and the constants for the equilibrium reactions for methylene formation (in situ monomer) need to be estimated. A mathematical model for the FTS allows for simulating several operating conditions and determining the best operating conditions to produce a specific product distribution, so the kinetic parameters must be statistically valid. This work used neural networks (NNs) to estimate the FTS kineti

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Angel, Sam, Abraham Marmur, and Ephraim Kehat. "Comparison of methods of prediction of vapor-liquid equilibria and enthalpy in a distillation simulation program." Computers & Chemical Engineering 10, no. 2 (1986): 169–80. http://dx.doi.org/10.1016/0098-1354(86)85028-1.

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Khazaee, Manoochehr, Emerson Christie, Weixiao Cheng, Mandy Michalsen, Jennifer Field та Carla Ng. "Perfluoroalkyl Acid Binding with Peroxisome Proliferator-Activated Receptors α, γ, and δ, and Fatty Acid Binding Proteins by Equilibrium Dialysis with a Comparison of Methods". Toxics 9, № 3 (2021): 45. http://dx.doi.org/10.3390/toxics9030045.

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The biological impacts of per- and polyfluorinated alkyl substances (PFAS) are linked to their protein interactions. Existing research has largely focused on serum albumin and liver fatty acid binding protein, and binding affinities determined with a variety of methods show high variability. Moreover, few data exist for short-chain PFAS, though their prevalence in the environment is increasing. We used molecular dynamics (MD) to screen PFAS binding to liver and intestinal fatty acid binding proteins (L- and I-FABPs) and peroxisome proliferator activated nuclear receptors (PPAR-α, -δ and -γ) wi

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Faghih-Mirzaee, Ehsan, Maryam Dehestani, and Leila Zeidabadinejad. "Computational study on transfer of L-ascorbic acid by UlaA throughEscherichia colimembrane." Journal of Bioinformatics and Computational Biology 15, no. 03 (2017): 1750007. http://dx.doi.org/10.1142/s021972001750007x.

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In this study, the transfer of L-ascorbic acid by UlaA through Escherichia coli (E. coli) membrane was evaluated using density functional theory (DFT), molecular docking, and molecular dynamics (MD) simulation methods. DFT calculations at the B3lyp/6[Formula: see text]311[Formula: see text]G(p,d) level were performed to investigate the interaction properties and molecular descriptors. The physical properties, such as chemical potential, chemical hardness, and chemical electrophilicity of all studied molecules, were investigated. Natural population analysis was employed to describe the state of

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Charpentier, Jean-Claude. "In the frame of globalization, some tracks for the future of chemical and process engineering." Chemical Industry and Chemical Engineering Quarterly 12, no. 2 (2006): 87–115. http://dx.doi.org/10.2298/ciceq0602087c.

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In today's economy, chemical engineering must respond to the changing needs of the chemical process industry in order to meet market demands. The evolution of chemical engineering is necessary to remain competitive in global trade. The ability of chemical engineering to cope with managing complex systems met in scientific and technological problems is addressed in this paper. Chemical Engineering is vital for sustainability: to satisfy both the market requirements for specific end-use properties of products and the social and environmental constraints of industrial-scale processes. An integrat

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Vargas Santillán, A., J. C. Farias Sanchez, M. G. Pineda Pimentel, and A. J. Castro Montoya. "Olefins and Ethanol from Polyolefins: Analysis of Potential Chemical Recycling of Poly(ethylene) Mexican Case." International Journal of Chemical Reactor Engineering 14, no. 6 (2016): 1289–300. http://dx.doi.org/10.1515/ijcre-2015-0217.

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Abstract Plastic solid waste (PSW) presents challenges and opportunities to society regardless of their sustainability awareness and technological advances. A special emphasis is paid on waste generated from polyolefin sources, which makes up a great percentage of our daily commodities’ plastic products. In Mexico 7.6 millions of tons of plastic in 2012 were wasted, which low density polyethylene LDPE, and high density polyethylene HDPE were the most abundant. Increasing cost, and decreasing space of landfills are forcing considerations of alternative options for PSW disposal. Years of researc

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Widiyanti, Dwi Retno. "Redistribution Adjusts Efficiency in Economy; Islamic Paradigm." Global Journal of Business and Social Science Review Vol. 2(4) 2014 2, no. 4 (2014): 18–27. http://dx.doi.org/10.35609/gjbssr.2014.2.4(3).

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Objective - Islam regulates distribution also redistribution of wealth, and how this concept break away the inefficiency of economic activity.The concept of redistribution has always been a debate in every microeconomics discussion in various areas, such as its mechanism, its implementation and also its effect on the efficiency of economies. This research is trying to examine how the concept of redistribution benefits the efficiency in economy through partial equilibrium analysis. The literature on the concept of Islamic paradigm and the positive paradigm are managed to produce a comprehensive

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Din, Qamar, and Muhammad Asad Iqbal. "Bifurcation Analysis and Chaos Control for a Discrete-Time Enzyme Model." Zeitschrift für Naturforschung A 74, no. 1 (2018): 1–14. http://dx.doi.org/10.1515/zna-2018-0254.

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AbstractBasically enzymes are biological catalysts that increase the speed of a chemical reaction without undergoing any permanent chemical change. With the application of Euler’s forward scheme, a discrete-time enzyme model is presented. Further investigation related to its qualitative behaviour revealed that discrete-time model shows rich dynamics as compared to its continuous counterpart. It is investigated that discrete-time model has a unique trivial equilibrium point. The local asymptotic behaviour of equilibrium is discussed for discrete-time enzyme model. Furthermore, with the help of

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Valdivia, Valeska, Benjamin Godard, Patrick Hennebelle, Maryvonne Gerin, Pierre Lesaffre, and Jacques Le Bourlot. "Origin of CH+ in diffuse molecular clouds." Astronomy & Astrophysics 600 (April 2017): A114. http://dx.doi.org/10.1051/0004-6361/201629905.

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Context. Molecular clouds are known to be magnetised and to display a turbulent and complex structure where warm and cold phases are interwoven. The turbulent motions within molecular clouds transport molecules, and the presence of magnetic fields induces a relative velocity between neutrals and ions known as the ion-neutral drift (vd). These effects all together can influence the chemical evolution of the clouds. Aims. This paper assesses the roles of two physical phenomena which have previously been invoked to boost the production of CH+ under realistic physical conditions: the presence of w

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Luo, Haishan, Emad W. Al-Shalabi, Mojdeh Delshad, Krishna Panthi, and Kamy Sepehrnoori. "A Robust Geochemical Simulator To Model Improved-Oil-Recovery Methods." SPE Journal 21, no. 01 (2016): 55–73. http://dx.doi.org/10.2118/173211-pa.

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Summary The interest in modeling geochemical reactions has increased significantly for different improved-oil-recovery processes such as alkali/surfactant/polymer (ASP) flood, low-salinity waterflood, and ethylenediaminetetraacetic acid (EDTA) injection as a sacrificial agent in hard brine. Numerical simulation of multiphase flow coupled with geochemical reactions is challenging because of complex and coupled aqueous, aqueous/solid, and aqueous/oleic reactions. These reactions have significant impact upon oil recovery, and hence a robust geochemical simulator is important. UTCHEM (2000) is a c

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D'Ambro, Emma L., Ben H. Lee, Jiumeng Liu, et al. "Molecular composition and volatility of isoprene photochemical oxidation secondary organic aerosol under low- and high-NO<sub><i>x</i></sub> conditions." Atmospheric Chemistry and Physics 17, no. 1 (2017): 159–74. http://dx.doi.org/10.5194/acp-17-159-2017.

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Abstract. We present measurements of secondary organic aerosol (SOA) formation from isoprene photochemical oxidation in an environmental simulation chamber at a variety of oxidant conditions and using dry neutral seed particles to suppress acid-catalyzed multiphase chemistry. A high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) utilizing iodide-adduct ionization coupled to the Filter Inlet for Gases and Aerosols (FIGAERO) allowed for simultaneous online sampling of the gas and particle composition. Under high-HO2 and low-NO conditions, highly oxygenated (O : C ≥

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Kajino, Mizuo, Makoto Deushi, Tsuyoshi Thomas Sekiyama, et al. "Comparison of three aerosol representations of NHM-Chem (v1.0) for the simulations of air quality and climate-relevant variables." Geoscientific Model Development 14, no. 4 (2021): 2235–64. http://dx.doi.org/10.5194/gmd-14-2235-2021.

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Abstract. This study provides comparisons of aerosol representation methods incorporated into a regional-scale nonhydrostatic meteorology–chemistry model (NHM-Chem). Three options for aerosol representations are currently available: the five-category non-equilibrium (Aitken, soot-free accumulation, soot-containing accumulation, dust, and sea salt), three-category non-equilibrium (Aitken, accumulation, and coarse), and bulk equilibrium (submicron, dust, and sea salt) methods. The three-category method is widely used in three-dimensional air quality models. The five-category method, the standard

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Ogunmola, B. Y., S. M. Abolarin, and A. O. Adelaja. "On the Prediction of Pollutant Emission [NO_x] in Internal Combustion Engine." Advanced Materials Research 824 (September 2013): 505–13. http://dx.doi.org/10.4028/www.scientific.net/amr.824.505.

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The study of internal chemical processes involving nitrogenous species forms an important part in the understanding of parameters which lower NOxemission from combustion systems. The focus of this research is to numerically model the prediction of formation of pollutant emission in a continuous internal combustion engine (ICE), from finite rate chemical equilibrium equations. The main source of nitrogen in the chemical formation of NOxis atmospheric, and a very small portion is caused by nitrogen compounds found in some fuels. A mathematical modeling was carried out with these equations using

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Hoare, Sam R. J. "The Problems of Applying Classical Pharmacology Analysis to Modern In Vitro Drug Discovery Assays: Slow Binding Kinetics and High Target Concentration." SLAS DISCOVERY: Advancing the Science of Drug Discovery 26, no. 7 (2021): 835–50. http://dx.doi.org/10.1177/24725552211019653.

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The analysis framework used to quantify drug potency in vitro (e.g., Kd or Ki) was initially developed for classical pharmacology bioassays, for example, organ bath experiments testing moderate-affinity natural products. Modern drug discovery can infringe the assumptions of the classical pharmacology analysis equations, owing to the reduction of assay volume in miniaturization, target overexpression, and the increase of compound–target affinity in medicinal chemistry. These assumptions are that (1) the compound concentration greatly exceeds the target concentration (i.e., minimal ligand deplet

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Schäbe, Alexander, Emilio Romano-Díaz, Cristiano Porciani, Aaron D. Ludlow, and Matteo Tomassetti. "A comparison of H2 formation models at high redshift." Monthly Notices of the Royal Astronomical Society 497, no. 4 (2020): 5008–23. http://dx.doi.org/10.1093/mnras/staa2313.

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ABSTRACT Modelling the molecular gas that is routinely detected through CO observations of high-redshift galaxies constitutes a major challenge for ab initio simulations of galaxy formation. We carry out a suite of cosmological hydrodynamic simulations to compare three approximate methods that have been used in the literature to track the formation and evolution of the simplest and most abundant molecule, H2. Namely, we consider (i) a semi-empirical procedure that associates H2 to dark-matter haloes based on a series of scaling relations inferred from observations, (ii) a model that assumes ch

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Ayodele, Bamidele V., and Chin Kui Cheng. "Process Modelling, Thermodynamic Analysis and Optimization of Dry Reforming, Partial Oxidation and Auto-Thermal Methane Reforming for Hydrogen and Syngas production." Chemical Product and Process Modeling 10, no. 4 (2015): 211–20. http://dx.doi.org/10.1515/cppm-2015-0027.

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Abstract In this work, process modelling, thermodynamic analysis and optimization of stand-alone dry and partial oxidation reforming of methane as well as, the auto-thermal reforming processes were investigated. Firstly, flowsheet models were developed for both the stand-alone systems and auto-thermal reforming process using ASPEN HYSYS®. Furthermore, thermodynamic studies were conducted for the stand-alone and auto-thermal reforming processes for temperatures range of 200–1000°C and pressure range of 1–3 bar using Gibbs free energy minimization methods which was also performed using ASPEN HYS

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Garcia-Tenorio, Camilo, Eduardo Mojica-Nava, Mihaela Sbarciog, and Alain Vande Wouwer. "Analysis of the ROA of an anaerobic digestion process via data-driven Koopman operator." Nonlinear Engineering 10, no. 1 (2021): 109–31. http://dx.doi.org/10.1515/nleng-2021-0009.

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Abstract Nonlinear biochemical systems such as the anaerobic digestion process experience the problem of the multi-stability phenomena, and thus, the dynamic spectrum of the system has several undesired equilibrium states. As a result, the selection of initial conditions and operating parameters to avoid such states is of importance. In this work, we present a data-driven approach, which relies on the generation of several system trajectories of the anaerobic digestion system and the construction of a data-driven Koopman operator to give a concise criterion for the classification of arbitrary

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Daley-Yates, Simon, Thomas Padioleau, Pascal Tremblin, Pierre Kestener, and Martial Mancip. "Idealised 3D simulations of diabatically forced Ledoux convection." Astronomy & Astrophysics 653 (September 2021): A54. http://dx.doi.org/10.1051/0004-6361/202040120.

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Aims. We investigate the impact of dimensionality, resolution, and long timescales on convective numerical simulations forced by thermo-compositional diabatic processes. We focus our study on simulations that are stable to the Schwarzschild criterion but unstable to the Ledoux one (i.e. simulations with a stabilising temperature gradient and a destabilising mean-molecular-weight gradient). We aim to establish the possibility of a reduced temperature gradient in such setups. Methods. A suite of 3D simulations incorporating both time series and convergence studies were conducted using a high-per

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Costa, Elinéia Castro, Welisson de Araújo Silva, Eduardo Gama Ortiz Menezes, et al. "Simulation of Organic Liquid Products Deoxygenation by Multistage Countercurrent Absorber/Stripping Using CO2 as Solvent with Aspen-HYSYS: Thermodynamic Data Basis and EOS Modeling." Molecules 26, no. 14 (2021): 4382. http://dx.doi.org/10.3390/molecules26144382.

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In this work, the thermodynamic data basis and equation of state (EOS) modeling necessary to simulate the fractionation of organic liquid products (OLP), a liquid reaction product obtained by thermal catalytic cracking of palm oil at 450 °C, 1.0 atmosphere, with 10% (wt.) Na2CO3 as catalyst, in multistage countercurrent absorber/stripping columns using supercritical carbon dioxide (SC-CO2) as solvent, with Aspen-HYSYS was systematically investigated. The chemical composition of OLP was used to predict the density (ρ), boiling temperature (Tb), critical temperature (Tc), critical pressure (Pc),

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Krienke, H. "Thermodynamical, structural, and dielectric properties of molecular liquids from integral equation theories and from simulations." Pure and Applied Chemistry 76, no. 1 (2004): 63–70. http://dx.doi.org/10.1351/pac200476010063.

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A survey is given on our attempts to calculate equilibrium properties of molecular liquids (pure solvents and electrolyte solutions) with the help of spatial pair correlation functions, starting from classical molecular pair interactions. The selection of potential models, especially the influence of molecular polarizability, is discussed as well as the limitations of the different methods of calculation of molecular pair correlation functions (e.g., from molecular and site-site Ornstein-Zernike theories, from MC and from MD simulations). We have performed simulations and integral equation cal

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Sidorenko, Oleg E., and Denis A. Rodnyansky. "Evaluation of fractal dimension of star polymers with different numbers of arms in computer experiment." Butlerov Communications 63, no. 7 (2020): 39–45. http://dx.doi.org/10.37952/roi-jbc-01/20-63-7-39.

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One of the important characteristics of a polymer molecule is its fractal dimension. Fractals are objects whose Hausdorff dimension is fractional and exceeds the topological dimension. The main distinguishing feature of such objects is self-similarity. The fractal characteristics of polymer macromolecules largely determine the chemical, physicochemical, and physical properties of these objects, such as the Mark-Kuhn-Houwink scaling parameters, toughness, tangent of the angle of mechanical losses, and dynamic modulus of elasticity. Today the fractal properties of topologically linear polymers a

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Tirupathi, Seshu, Jan S. Hesthaven, and Yan Liang. "Modeling 3D Magma Dynamics Using a Discontinuous Galerkin Method." Communications in Computational Physics 18, no. 1 (2015): 230–46. http://dx.doi.org/10.4208/cicp.090314.151214a.

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AbstractDiscontinuous Galerkin (DG) and matrix-free finite element methods with a novel projective pressure estimation are combined to enable the numerical modeling of magma dynamics in 2D and 3D using the library deal.II. The physical model is an advection-reaction type system consisting of two hyperbolic equations to evolve porosity and soluble mineral abundance at local chemical equilibrium and one elliptic equation to recover global pressure. A combination of a discontinuous Galerkin method for the advection equations and a finite element method for the elliptic equation provide a robust a

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Mahmoudvand, Saba, Behnam Shahsavani, Rafat Parsaei, and Mohammad Reza Malayeri. "Prediction of asphaltene precipitation upon injection of various gases at near-wellbore conditions: A simulation study using PC-SAFT EoS." Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles 74 (2019): 63. http://dx.doi.org/10.2516/ogst/2019037.

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The depletion of oil reservoirs and increased global oil demand have given impetus to employ various secondary and tertiary oil recovery methods. Gas injection is widely used in both secondary and tertiary modes, though the major problem associated with this process is the precipitation and deposition of asphaltene, particularly at near-wellbore conditions. In-depth knowledge of asphaltene phase behavior is therefore essential for the prediction of asphaltene precipitation. Previous studies reported the impact of gas injection on asphaltene phase behavior, but the knowledge of precipitation of

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Awan, Aziz Ullah, Attia Sharif, Kashif Ali Abro, Muhammad Ozair, and Takasar Hussain. "Dynamical aspects of smoking model with cravings to smoke." Nonlinear Engineering 10, no. 1 (2021): 91–108. http://dx.doi.org/10.1515/nleng-2021-0008.

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Abstract The square-root dynamics of smoking model with cravings to smoke, in which square root of potential smokers and smokers is the interaction term, has been studied. We categorized net population in four different chambers: non-smokers/potential smokers, smokers/infected people, non-permanent smokers/temporary quitters and the permanent quitters. By dynamical systems approach, we analyzed our model. Moreover, for proving the unique equilibrium point to be globally stable, we took help of graph theoretic approach. The sensitivity analysis of the model is performed through the diseased cla

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Wargnier, Q., A. Alvarez Laguna, J. B. Scoggins, N. N. Mansour, M. Massot, and T. E. Magin. "Consistent transport properties in multicomponent two-temperature magnetized plasmas." Astronomy & Astrophysics 635 (March 2020): A87. http://dx.doi.org/10.1051/0004-6361/201834686.

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Aims. We present a fluid model that has been developed for multicomponent two-temperature magnetized plasmas in chemical non-equilibrium for the partially to fully ionized collisional regimes. We focus on transport phenomena with the aim of representing the atmosphere of the Sun. Methods. This study is based on an asymptotic fluid model for multicomponent plasmas derived from kinetic theory, yielding a rigorous description of the dissipative effects. The governing equations and consistent transport properties are obtained using a multiscale Chapman-Enskog perturbative solution to the Boltzmann

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Cullen, John F. "Computer simulation of chemical equilibrium." Journal of Chemical Education 66, no. 12 (1989): 1023. http://dx.doi.org/10.1021/ed066p1023.

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Oguike, R. S., A. M. Kolo, A. M. Shibdawa, and H. A. Gyenna. "Density Functional Theory of Mild Steel Corrosion in Acidic Media Using Dyes as Inhibitor: Adsorption onto Fe(110) from Gas Phase." ISRN Physical Chemistry 2013 (April 9, 2013): 1–9. http://dx.doi.org/10.1155/2013/175910.

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Quantum chemical calculations based on density functional theory (DFT) methods were performed on indigo blue (IB), methylene blue (MB), and crystal violet (CV) molecules as inhibitors for iron corrosion in acid media. DFT calculations were performed on the molecular structures to describe electronic parameters which are associated with inhibition efficiency such as the values −4.981 eV, −4.518 eV, and −3.872 eV which increased in the order IB > MB > CV while values were −3.73 eV, −3.63 eV, and −2.87 eV for IB, MB, and CV, respectively. Quench molecular dynamics simulations performed at m

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Shakil, Shazi, Syed M. Danish Rizvi, and Nigel H. Greig. "High Throughput Virtual Screening and Molecular Dynamics Simulation for Identifying a Putative Inhibitor of Bacterial CTX-M-15." Antibiotics 10, no. 5 (2021): 474. http://dx.doi.org/10.3390/antibiotics10050474.

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Background: Multidrug resistant bacteria are a major therapeutic challenge. CTX-M-type enzymes are an important group of class A extended-spectrum β-lactamases (ESBLs). ESBLs are the enzymes that arm bacterial pathogens with drug resistance to an array of antibiotics, notably the advanced-generation cephalosporins. The current need for an effective CTX-M-inhibitor is high. Objective: The aim of the current study was to identify a promising anti-CTX-M-15 ligand whose chemical skeleton could be used as a ‘seed-molecule’ for future drug design against resistant bacteria. Methods: Virtual screenin

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Warshel, Arieh, and William W. Parson. "Dynamics of biochemical and biophysical reactions: insight from computer simulations." Quarterly Reviews of Biophysics 34, no. 4 (2001): 563–679. http://dx.doi.org/10.1017/s0033583501003730.

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1. Introduction 5632. Obtaining rate constants from molecular-dynamics simulations 5642.1 General relationships between quantum electronic structures and reaction rates 5642.2 The transition-state theory (TST) 5692.3 The transmission coefficient 5723. Simulating biological electron-transfer reactions 5753.1 Semi-classical surface-hopping and the Marcus equation 5753.2 Treating quantum mechanical nuclear tunneling by the dispersed-polaron/spin-boson method 5803.3 Density-matrix treatments 5833.4 Charge separation in photosynthetic bacterial reaction centers 5844. Light-induced photoisomerizatio

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Correia, António Ferrer, João C. M. Paiva, and Victor M. S. Gil. "Le Chat: Simulation in Chemical Equilibrium." Journal of Chemical Education 79, no. 5 (2002): 640. http://dx.doi.org/10.1021/ed079p640.

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Paiva, João C. M., Victor M. S. Gil, and António Ferrer Correia. "Le Chat: Simulation in Chemical Equilibrium." Journal of Chemical Education 80, no. 1 (2003): 111. http://dx.doi.org/10.1021/ed080p111.

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Helling, Ch, P. Gourbin, P. Woitke, and V. Parmentier. "Sparkling nights and very hot days on WASP-18b: the formation of clouds and the emergence of an ionosphere." Astronomy & Astrophysics 626 (June 2019): A133. http://dx.doi.org/10.1051/0004-6361/201834085.

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Context. WASP-18b is an ultra-hot Jupiter with a temperature difference of up to 2500 K between day and night. Such giant planets begin to emerge as a planetary laboratory for understanding cloud formation and gas chemistry in well-tested parameter regimes in order to better understand planetary mass loss and for linking observed element ratios to planet formation and evolution. Aims. We aim to understand where clouds form, their interaction with the gas-phase chemistry through depletion and enrichment, the ionisation of the atmospheric gas, and the possible emergence of an ionosphere on ultra

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