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Relevant bibliographies by topics / Diffusion controlled reactions

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Academic literature on the topic 'Diffusion controlled reactions'

Author: Grafiati

Published: 4 June 2021

Last updated: 4 February 2022

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Journal articles on the topic "Diffusion controlled reactions"

1

ZHOU, Guo-Qiang, and Wei-Zhu ZHONG. "Diffusion-Controlled Reactions of Enzymes." European Journal of Biochemistry 128, no. 2-3 (March 3, 2005): 383–87. http://dx.doi.org/10.1111/j.1432-1033.1982.tb06976.x.

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Burlatsky, S. F., and G. S. Oshanin. "Diffusion-controlled reactions with polymers." Physics Letters A 145, no. 1 (March 1990): 61–65. http://dx.doi.org/10.1016/0375-9601(90)90278-v.

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Berezhkovskii, A. M., Yu A. Makhnovskii, and R. A. Suris. "Kinetics of diffusion-controlled reactions." Chemical Physics 137, no. 1-3 (October 1989): 41–49. http://dx.doi.org/10.1016/0301-0104(89)87091-0.

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Ayscough, Peter B., Keith D. Bartle, Anthony A. Clifford, and Derek Mills. "Measurement of diffusion coefficients for diffusion-controlled reactions." International Journal of Chemical Kinetics 20, no. 11 (November 1988): 849–55. http://dx.doi.org/10.1002/kin.550201103.

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Mazor, Michael H., Chung F. Wong, J. Andrew McCammon, John M. Deutch, and George Whitesides. "Effective molarity in diffusion-controlled reactions." Journal of Physical Chemistry 94, no. 9 (May 1990): 3807–12. http://dx.doi.org/10.1021/j100372a084.

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Moreau, M., G. Oshanin, O. Bénichou, and M. Coppey. "Stochastic theory of diffusion-controlled reactions." Physica A: Statistical Mechanics and its Applications 327, no. 1-2 (September 2003): 99–104. http://dx.doi.org/10.1016/s0378-4371(03)00458-8.

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Szabo, Attila, Robert Zwanzig, and Noam Agmon. "Diffusion-Controlled Reactions with Mobile Traps." Physical Review Letters 61, no. 21 (November 21, 1988): 2496–99. http://dx.doi.org/10.1103/physrevlett.61.2496.

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Argyrakis, Panos, Harvey Gould, and Jan Tobochnik. "Simulation of Diffusion-Controlled Chemical Reactions." Computers in Physics 6, no. 5 (1992): 525. http://dx.doi.org/10.1063/1.4823102.

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Durning, Chris, and Ben O’Shaughnessy. "Diffusion controlled reactions at an interface." Journal of Chemical Physics 88, no. 11 (June 1988): 7117–28. http://dx.doi.org/10.1063/1.454362.

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Mita, Itaru, and Kazuyuki Horie. "Diffusion-Controlled Reactions in Polymer Systems." Journal of Macromolecular Science, Part C: Polymer Reviews 27, no. 1 (February 1987): 91–169. http://dx.doi.org/10.1080/07366578708078641.

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Dissertations / Theses on the topic "Diffusion controlled reactions"

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Abercrombie, Stuart Christopher Benedict. "Numerical simulation of diffusion controlled reactions." Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401748.

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Wang, Aileen Ruiling Zhu Shiping. "Diffusion-controlled atom transfer radical polymerization." *McMaster only, 2005.

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Bracht, Hartmut. "Diffusion and defect reactions in isotopically controlled semiconductors." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-192855.

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Point defects in semiconductors play a decisive role for the functionality of semiconductors. A detailed, quantitative understanding of diffusion and defect reactions of dopants is required for advanced modelling of modern nanometer size electronic devices. With isotope heterostructures which consist of epitaxial layers of isotopically pure and deliberately mixed stable isotopes, we have studied the simultaneous self- and dopant diffusion in several major semiconductors such as silicon and germanium. Detailed analysis of the simultaneous diffusion of self- and dopant atoms in Si and Ge yields information about the ionization levels of native defects and about dopant-defect interactions in Si and Ge. The results of these diffusion studies are highlighted in this work.

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Bracht, Hartmut. "Diffusion and defect reactions in isotopically controlled semiconductors." Diffusion fundamentals 8 (2008) 1, S. 1-8, 2008. https://ul.qucosa.de/id/qucosa%3A14147.

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Point defects in semiconductors play a decisive role for the functionality of semiconductors. A detailed, quantitative understanding of diffusion and defect reactions of dopants is required for advanced modelling of modern nanometer size electronic devices. With isotope heterostructures which consist of epitaxial layers of isotopically pure and deliberately mixed stable isotopes, we have studied the simultaneous self- and dopant diffusion in several major semiconductors such as silicon and germanium. Detailed analysis of the simultaneous diffusion of self- and dopant atoms in Si and Ge yields information about the ionization levels of native defects and about dopant-defect interactions in Si and Ge. The results of these diffusion studies are highlighted in this work.

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Hannech, El Bahi. "Diffusion-controlled reactions in gold/lead-tin solder systems." Thesis, University of Warwick, 1989. http://wrap.warwick.ac.uk/106459/.

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Au/PbSn joints are widely used in the microelectronics industry. Intermetallic formation in Au/60Sn-40wt. %Pb and in Au/62Sn-36Pb-2wt. %Ag systems has been studied in the temperature range 80°C-160°C using diffusion couples. Interdiffusion between Au films and 60Sn-40wt. %Pb solder doped with 2 wt. % zinc has also been studied but at 125°C only, also using diffusion couples. The intermetallic phases were identified by Energy Dispersive X-ray Analysis (EDAX) in the Scanning Electron Microscope (SEM) and found to be gold-tin compounds. The predominant phases were found to be AuSn4 and AuSn2 but all the phases predicted in that range of temperatures by the equilibrium phase diagram of the Au-Sn system were present in the couples after long annealing times. The kinetics of the intermetallic layers were determined and an activation energy for the growth of the layer of AuSn4 of 0.84 ± 0.02 eV was found. The effect of both silver and zinc on the growth rates of the intermetallic layers were determined. It was found that both additives reduce the intermetallic layer growth rates. In addition to the Au-Sn intermetallics, a compound layer of composition Au0.3Sn0.3Zn0.4 forms between the AuSn4 layer and the solder in the Au/PbSnZn system. The tensile strengths of the joints, before and after aging, were also evaluated and the weak bonds within the joints identified. It was found that the weak bonds within a Au/PbSn joint, with or without silver in the solder, were the intermetallic layer interfaces. The joint tensile strength is not weakened by the increase of the intermetallic layer thicknesses with aging time. Joint weakening occurs after degradation of the gold film of the joint, but that happens a long aging time after the depletion of the gold film. The joint made with the zinc containing solder was found to lose strength rapidly after aging. The weak area of the joint is the solder/wire interface.

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Sereshki, Leila Esmaeili [Verfasser], Ralf [Akademischer Betreuer] Metzler, and Martin [Akademischer Betreuer] Zacharias. "Modelling diffusion controlled reactions in living cells / Leila Esmaeili Sereshki. Gutachter: Martin Zacharias. Betreuer: Ralf Metzler." München : Universitätsbibliothek der TU München, 2012. http://d-nb.info/1021975907/34.

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Reigada, Sanz Ramon. "Effects of some mixing flows on diffusion-controlled reactions = Efectes d'alguns fluxes de mescla en reaccions controlades per difusió." Doctoral thesis, Universitat de Barcelona, 1997. http://hdl.handle.net/10803/666101.

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Los sistemas de reacción-difusión donde el proceso difusivo es la etapa lenta están controlados, a bajas dimensionalidades, por las fluctuaciones en las distribuciones iniciales de reactivos. Concretamente, estos sistemas se segregan en dominios de las diferentes especies obteniéndose comportamientos cinéticos anómalos. Estudiamos estos comportamientos no formales en el sistema reactivo binario A+B=O mediante la explotación analítica y numérica de las ecuaciones deterministas de reacción-difusión para las concentraciones locales de ambos reactivos suponiendo válida la aproximación de campo medio para el término de reacción. En una segunda parte del trabajo se ha incorporado al modelo un tercer proceso, el de mezcla, con el que intentamos homogeneizar el sistema y recuperar el comportamiento cinético clásico. Trabajamos principalmente con dos flujos hidrodinámicos bidimensionales, el de red de remolinos y el turbulento. Si bien en ambos casos a tiempos intermedios recuperamos la conducta clásica, a tiempos suficientemente grandes conseguimos evitar la segregación del sistema.

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Kasahara, Kento. "Integral Equation Theories of Diffusion and Solvation for Molecular Liquids." Kyoto University, 2018. http://hdl.handle.net/2433/232056.

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BOUDIBA, NASSIMA. "Existence globale pour des systemes de reaction-diffusion avec controle de masse." Rennes 1, 1999. http://www.theses.fr/1999REN10125.

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Ce travail est une contribution a l'etude de l'existence globale en temps de solutions pour des systemes de reaction-diffusion ou la structure des non-linearites assure a priori que la masse totale de la solution est uniformement bornee. Ce type de systemes apparait souvent dans les applications. Notre premiere contribution consiste a examiner l'influence de la dependance en le gradient des solutions dans les termes non-lineaires et des donnees initiales seulement integrables. Nous adoptons le point de vue de solution faible. Dans la seconde partie de ce travail, nous considerons le cas des systemes de reaction-diffusion fortement couples et semi-lineaires. Un premier resultat montre precisement que nous ne pouvons pas esperer d'existence globale de solutions classiques dans cette situation generale. Par contre si le couplage est seulement triangulaire, la situation est meilleure. Enfin, nous nous interessons a une classe de systemes de reaction-diffusion faiblement couples et semi-lineaires ou les non-linearites changent de signe : il s'agit d'etendre le critere d'existence globale connu dans le cas de donnees initiales bornees au cas de donnees initiales seulement integrables. Nous prouvons d'autre part l'existence d'effets regularisants pour montrer la regularite de la solution obtenue.

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Tang, Kunkun. "Combining Discrete Equations Method and Upwind Downwind-Controlled Splitting for Non-Reacting and Reacting Two-Fluid Computations." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00819824.

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Lors que nous examinons numériquement des phénomènes multiphasiques suite à un accidentgrave dans le réacteur nucléaire, la dimension caractéristique des zones multi-fluides(non-réactifs et réactifs) s'avère beaucoup plus petite que celle du bâtiment réacteur, cequi fait la Simulation Numérique Directe de la configuration à peine réalisable. Autrement,nous proposons de considérer la zone de mélange multiphasique comme une interface infinimentfine. Puis, le solveur de Riemann réactif est inséré dans la Méthode des ÉquationsDiscrètes Réactives (RDEM) pour calculer le front de combustion à grande vitesse représentépar une interface discontinue. Une approche anti-diffusive est ensuite couplée avec laRDEM afin de précisément simuler des interfaces réactives. La robustesse et l'efficacité decette approche en calculant tant des interfaces multiphasiques que des écoulements réactifssont à la fois améliorées grâce à la méthode ici proposée : upwind downwind-controlled splitting(UDCS). UDCS est capable de résoudre précisément des interfaces avec les maillagesnon-structurés multidimensionnels, y compris des fronts réactifs de détonation et de déflagration.

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Books on the topic "Diffusion controlled reactions"

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Gusak, Andriy M., Yuriy A. Lyashenko, Semen V. Kornienko, Mykola O. Pasichnyy, Aram S. Shirinyan, and Tatyana V. Zaporozhets, eds. Diffusion-Controlled Solid State Reactions. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2010. http://dx.doi.org/10.1002/9783527631025.

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Rehm, Ronald G. Diffusion-controlled reaction in a vortex field. Gaithersburg, MD: U.S. Dept. of Commerce, National Bureau of Standards, Center for Applied Mathematics and Center for Fire Research, 1987.

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Rehm, Ronald G. Diffusion-controlled reaction in a vortex field. Gaithersburg, MD: U.S. Dept. of Commerce, National Bureau of Standards, Center for Applied Mathematics and Center for Fire Research, 1987.

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Rehm, Ronald G. Diffusion-controlled reaction in a vortex field. Gaithersburg, MD: U.S. Dept. of Commerce, National Bureau of Standards, Center for Applied Mathematics and Center for Fire Research, 1987.

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Rehm, Ronald G. Diffusion-controlled reaction in a vortex field. Gaithersburg, MD: U.S. Dept. of Commerce, National Bureau of Standards, Center for Applied Mathematics and Center for Fire Research, 1987.

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Rehm, Ronald G. Diffusion-controlled reaction in a vortex field. Gaithersburg, MD: U.S. Dept. of Commerce, National Bureau of Standards, Center for Applied Mathematics and Center for Fire Research, 1987.

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Hannech, El Bahi. Diffusion-controlled reactions in gold/lead-tin solder systems. [s.l.]: typescript, 1989.

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8

N, Kuzovkov V., ed. Modern aspects of diffusion-controlled reactions: Cooperative phenomena in bimolecular processes. Amsterdam: Elsevier, 1996.

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Williford, Ralph Eric. Matrix creep accommodation in a diffusion controlled phase transformation. 1994.

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Gusak, Andriy M., Yu O. Lyashenko, T. V. Zaporozhets, S. V. Kornienko, and M. O. Pasichnyy. Diffusion-Controlled Solid State Reactions: In Alloys, Thin Films and Nanosystems. Wiley & Sons, Limited, John, 2010.

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Book chapters on the topic "Diffusion controlled reactions"

1

Lõpez-Quintela, M. Arturo, and Wilhelm Knoche. "Fractals in Diffusion-Controlled Kinetics." In Reactions in Compartmentalized Liquids, 199–210. Berlin, Heidelberg: Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-74787-8_21.

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Gusak, Andriy M. "Introduction." In Diffusion-Controlled Solid State Reactions, 1–9. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2010. http://dx.doi.org/10.1002/9783527631025.ch1.

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Lyashenko, Yuriy A., and Andriy M. Gusak. "Interdiffusion with Formation and Growth of Two-Phase Zones." In Diffusion-Controlled Solid State Reactions, 333–58. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2010. http://dx.doi.org/10.1002/9783527631025.ch10.

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Gusak, Andriy M., and Yuriy A. Lyashenko. "The Problem of Choice of Reaction Path and Extremum Principles." In Diffusion-Controlled Solid State Reactions, 359–80. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2010. http://dx.doi.org/10.1002/9783527631025.ch11.

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Lyashenko, Yuriy A. "Choice of Optimal Regimes in Cellular Decomposition, Diffusion-Induced Grain Boundary Migration, and the Inverse Diffusion Problem." In Diffusion-Controlled Solid State Reactions, 381–424. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2010. http://dx.doi.org/10.1002/9783527631025.ch12.

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Shirinyan, Aram S., and Andriy M. Gusak. "Nucleation and Phase Separation in Nanovolumes." In Diffusion-Controlled Solid State Reactions, 425–74. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2010. http://dx.doi.org/10.1002/9783527631025.ch13.

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Gusak, Andriy M. "Nonequilibrium Vacancies and Diffusion-Controlled Processes at Nanolevel." In Diffusion-Controlled Solid State Reactions, 11–35. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2010. http://dx.doi.org/10.1002/9783527631025.ch2.

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Gusak, Andriy M. "Diffusive Phase Competition: Fundamentals." In Diffusion-Controlled Solid State Reactions, 37–60. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2010. http://dx.doi.org/10.1002/9783527631025.ch3.

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Gusak, Andriy M. "Nucleation in a Concentration Gradient." In Diffusion-Controlled Solid State Reactions, 61–98. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2010. http://dx.doi.org/10.1002/9783527631025.ch4.

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Pasichnyy, Mykola O., and Andriy M. Gusak. "Modeling of the Initial Stages of Reactive Diffusion." In Diffusion-Controlled Solid State Reactions, 99–133. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2010. http://dx.doi.org/10.1002/9783527631025.ch5.

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Conference papers on the topic "Diffusion controlled reactions"

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Andre, Jean-Claude, F. Baros, Wei Dong, Jean Duhamel, and A. T. Reis e Sousa. "Diffusion-controlled reactions: molecular dynamics, continuous modeling, and experimentation." In OE/LASE '90, 14-19 Jan., Los Angeles, CA, edited by Joseph R. Lakowicz. SPIE, 1990. http://dx.doi.org/10.1117/12.17706.

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Asano, T., K. Cosstick, and H. Furuta. "Experimental evidence for a two-step mechanism of diffusion-controlled unimolecular reactions." In High-pressure science and technology—1993. AIP, 1994. http://dx.doi.org/10.1063/1.46455.

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Wu, Bei, and Hui Zhang. "A Thermal Transport and Non-Equilibrium Deposition Model in AlN Sublimation Growth Process." In ASME 2005 Summer Heat Transfer Conference collocated with the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems. ASMEDC, 2005. http://dx.doi.org/10.1115/ht2005-72257.

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Sublimation vapor transport method is a widely used technique for production of bulk crystals, such as SiC and AlN. A one-step reaction with two vapor species, i.e. aluminum (Al) vapor and nitrogen (N2) gas, is usually assumed for AlN sublimation growth with diffusion-controlled growth mechanism. However, vapor species generation/consumption is determined by surface reactions, which do not depend on the concentration gradient, but on concentration itself. Thus, the flux at the interfaces is controlled not only by the Fick’s law, but by the surface reaction. In this paper, inductively heated AlN sublimation growth process is simulated to predict the heat generation and temperature field in the growth system. The effects of coil position on heat and mass transfer are investigated. A non-equilibrium growth model considering surface reaction on the source/seed surfaces, diffusion within the boundary layers and vapor transport between source and seed is developed to predict the growth rates at different operating conditions. The predicted results are compared with the experimental data and the results from a traditional diffusion model, which assumes thermodynamic equilibrium on the solid/vapor surface/interface and vapor diffusion through bulk gas. The conditions under which the new model will provide the same as the one obtained by the diffusion model are identified.

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Kuznetsov, Vladmir V., Oleg V. Vitovsky, and Stanislav P. Kozlov. "Heat and Mass Transfer With Chemical Reactions Producing Hydrogen in Microchannels." In ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2011. http://dx.doi.org/10.1115/icnmm2011-58203.

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The reduction of effective transfer length on microscale eliminates the external diffusion limitation on reaction rate and makes it possible to realize the non-equilibrium chemical reactions. The peculiarities of methane and carbon monoxide steam reforming in a minichannel reactor with activation of reactions on thin film catalyst prepared by nanotechnology are considered in this paper. Consistent accomplishment of these reactions can increase the hydrogen yield and reduce the concentration of carbon monoxide in the product. Steam reforming of methane was studied on Rh/Al2O3 nanocatalyst deposited on the inner wall of the annular minichannel. Steam reforming of carbon monoxide was studied at Pt/CeO2/Al2O3 nanocatalyst deposited on the walls of the minichannel plate. The procedure of catalyst preparation which makes the nanoparticles of two nanometers in size is developed. The catalyst has uniform fraction of nanoparticles and optimal oxygen mobility in the lattice of carrier. During tests the data on the composition of the reacting gas mixture in temperature range from 200 C to 940 C were obtained including data on conversion in controlled temperature field when hydrogen content in the product reaches 68% and carbon monoxide content reduces to 1%. Methane steam reforming and water gas shift reaction in the minichannel were modeled numerically. The detailed information on the temperature and species concentration fields has been obtained, and kinetics of multistage reactions was defined when the external heat is supplied to proceed the steam reforming. The temperature regimes of high conversion of methane and carbon monoxide were defined and discussed in connection with the experimental data.

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Stamatiou, Anastasia, Peter G. Loutzenhiser, and Aldo Steinfeld. "Solar Syngas Production From H2O and CO2 via Two Step Thermochemical Cycles Based on FeO/Fe3O4 Redox Reactions: Kinetic Analysis." In ASME 2010 4th International Conference on Energy Sustainability. ASMEDC, 2010. http://dx.doi.org/10.1115/es2010-90009.

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Syngas production via a two-step H2O/CO2-splitting thermochemical cycle based on FeO/Fe3O4 redox reactions is considered using highly concentrated solar process heat. The closed cycle consists of: 1) the solar-driven endothermic dissociation of Fe3O4 to FeO; 2) the non-solar exothermic simultaneous reduction of CO2 and H2O with FeO to CO and H2 and the initial metal oxide; the latter is recycled to the first step. The second step was experimentally investigated by thermogravimetry for reactions with FeO in the range 973–1273 K and CO2/H2O concentrations of 15–75%. The reaction mechanism was characterized by an initial fast interface-controlled regime followed by a slower diffusion-controlled regime. A rate law of Langmuir-Hinshelwood type was formulated to describe the competitiveness of the reaction based on atomic oxygen exchange on active sites, and the corresponding Arrhenius kinetic parameters were determined by applying a shrinking core model.

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Asano, Yukako, Shigenori Togashi, and Yoshishige Endo. "Optimization of Chemical Reaction Processes in Microreactors Using Reaction Rate Analyses." In ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-36013.

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We applied microreactors to the three following reactions: a consecutive bromination reaction, the two-step Sandmeyer reaction, and an acetylation reaction including solvent effects. We obtained the reaction rate constants from few experimental data or quantum chemical calculations and optimized the reaction conditions such as the reaction times and temperature. We then experimentally validated them by microreactors. A consecutive bromination reaction, where the objective reaction was followed by the side reaction, was one of the processes. The reaction temperature played an important role in the effects of a microreactor. The yield of the objective product was improved by about 40% using a microreactor. The two-step Sandmeyer reaction was also applied, where the 1st-step reaction was followed by the 2nd-step reaction to produce the objective product. The 1st-step reaction had the diffusion-controlled process, while the 2nd-step reaction had the reaction-controlled one. The yield of the objective product was improved when microreactors were used and the reaction time for the 2nd-step reaction was set appropriately. Moreover, an acetylation reaction including solvent effects on reaction rates was considered and the solvent effects could be predicted from quantum chemical calculations. The calculation suggested that acetic acid with the larger electron-accepting property gave more stability to the species formed in the transition state. The reaction time was shortened using a microreactor, when the reaction process was changed from reaction-controlled to diffusion-controlled by changing the solvent used.

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Balas, Mark J. "Augmentation of Fixed Gain Controlled Infinite Dimensional Systems With Direct Adaptive Control." In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23179.

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Abstract Linear infinite dimensional systems are described by a closed, densely defined linear operator that generates a continuous semigroup of bounded operators on a general Hilbert space of states and are controlled via a finite number of actuators and sensors. Many distributed applications are included in this formulation, such as large flexible aerospace structures, adaptive optics, diffusion reactions, smart electric power grids, and quantum information systems. In this paper, we focus on infinite dimensional linear systems for which a fixed gain linear infinite or finite dimensional controller is already in place. We augment this controller with a direct adaptive controller that will maintain stability of the full closed loop system even when the fixed gain controller fails to do so. We prove that the transmission zeros of the combined system are the original open loop transmission zeros, and the point spectrum of the controller alone. Therefore, the combined plant plus controller is Almost Strictly Dissipative (ASD) if and only if the original open loop system is minimum phase, and the fixed gain controller alone is exponentially stable. This result is true whether the fixed gain controller is finite or infinite dimensional. In particular this guarantees that a controller for an infinite dimensional plant based on a reduced -order approximation can be stabilized by augmentation with direct adaptive control to mitigate risks. These results are illustrated by application to direct adaptive control of general linear diffusion systems on a Hilbert space that are described by self-adjoint operators with compact resolvent.

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Mudunuru, M. K., M. Shabouei, and K. B. Nakshatrala. "On Local and Global Species Conservation Errors for Nonlinear Ecological Models and Chemical Reacting Flows." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-52760.

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Advection-controlled and diffusion-controlled oscillatory chemical reactions appear in various areas of life sciences, hydrogeological systems, and contaminant transport. In this conference paper, we analyze whether the existing numerical formulations and commercial packages provide physically meaningful values for concentration of the chemical species for two popular oscillatory chemical kinetic schemes. The first one corresponds to the chlorine dioxide-iodine-malonic acid reaction while the second one is a simplified version of Belousov-Zhabotinsky reaction of a non-linear chemical oscillator. The governing equations for species balance are presented based on the theory of interacting continua. This results in a set of coupled non-linear partial differential equations. Obtaining analytical solutions is not practically viable. Moreover, it is well-known in literature that if the local dynamics becomes complex, the range of possible dynamic behavior in the presence of diffusion and advection becomes practically unlimited. We resort to numerical solutions, which are obtained using two popular stabilized formulations: Streamline Upwind/Petrov Galerkin and Galerkin/Least Squares. In order to make the computational analysis tractable, an estimate on the range of system-dependent parameters is obtained based on model reduction performed on the strong-form of the governing equations. Finally, we quantify the errors in satisfying the local and global species balance for various realistic benchmark problems. Through these representative numerical examples, we shall demonstrate the need and importance of developing locally conservative non-negative numerical formulations for chaotic and oscillatory chemically reacting systems.

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9

Yoshida, Jun-ichi, and Aiichiro Nagaki. "Flash Chemistry - Fast Chemical Synthesis in Micro Flow Systems." In ASME 2009 7th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2009. http://dx.doi.org/10.1115/icnmm2009-82157.

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Flash chemistry is a field of chemical synthesis where extremely fast reactions are conducted in a highly controlled manner. A key element of flash chemistry is the control of extremely fast reactions to obtain the desired products selectively. For extremely fast reactions, kinetics often cannot be used because of the lack of homogeneity of the reaction environment when they are conducted in conventional reactors such as flasks. Fast micromixing by virtue of short diffusion path solves such problems. Fast reactions are usually highly exothermic, and heat removal is an important factor in controlling such reactions. Heat transfer occurs very rapidly in micro flow systems by virtue of a large surface area per unit volume, making precise temperature control possible. Another important point is that fast reactions often involve highly unstable intermediates, which decompose very quickly, making reaction control difficult. The residence time can be greatly reduced in micro flow systems, and this feature is quite effective in controlling such reactions. The concept of flash chemistry has been successfully applied to various organic reactions for synthesis including (a) reactions in which undesired byproducts are produced in the subsequent reactions in conventional reactors, (b) highly exothermic reactions that are difficult to control in conventional reactors, and (c) reactions in which a reactive intermediate easily decomposes in conventional reactors. The concept of flash chemistry can be also applied to polymer synthesis. Cationic polymerization can be conducted with an excellent level of molecular-weight control and molecular-weight distribution control. Radical polymerization in micro flow systems leads to better molecular weight distribution control than macro batch systems. Anionic polymerization can also be carried out micro flow systems at higher temperatures than macro batch systems with high degree of molecular weight distribution control.

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10

Balas, Mark J., and Susan A. Frost. "A Stabilization of Fixed Gain Controlled Infinite Dimensional Systems by Augmentation With Direct Adaptive Control." In ASME 2017 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/smasis2017-3726.

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Linear infinite dimensional systems are described by a closed, densely defined linear operator that generates a continuous semigroup of bounded operators on a general Hilbert space of states and are controlled via a finite number of actuators and sensors. Many distributed applications are included in this formulation, such as large flexible aerospace structures, adaptive optics, diffusion reactions, smart electric power grids, and quantum information systems. We have developed the following stability result: an infinite dimensional linear system is Almost Strictly Dissipative (ASD) if and only if its high frequency gain CB is symmetric and positive definite and the open loop system is minimum phase, i.e. its transmission zeros are all exponentially stable. In this paper, we focus on infinite dimensional linear systems for which a fixed gain linear infinite or finite dimensional controller is already in place. It is usually true that fixed gain controllers are designed for particular applications but these controllers may not be able to stabilize the plant under all variations in the operating domain. Therefore we propose to augment this fixed gain controller with a relatively simple direct adaptive controller that will maintain stability of the full closed loop system over a much larger domain of operation. This can ensure that a flexible structure controller based on a reduced order model will still maintain closed-loop stability in the presence of unmodeled system dynamics. The augmentation approach is also valuable to reduce risk in loss of control situations. First we show that the transmission zeros of the augmented infinite dimensional system are the open loop plant transmission zeros and the eigenvalues (or poles) of the fixed gain controller. So when the open-loop plant transmission zeros are exponentially stable, the addition of any stable fixed gain controller does not alter the stability of the transmission zeros. Therefore the combined plant plus controller is ASD and the closed loop stability when the direct adaptive controller augments this combined system is retained. Consequently direct adaptive augmentation of controlled linear infinite dimensional systems can produce robust stabilization even when the fixed gain controller is based on approximation of the original system. These results are illustrated by application to a general infinite dimensional model described by nuclear operators with compact resolvent which are representative of distributed parameter models of mechanically flexible structures. with a reduced order model based controller and adaptive augmentation.

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Reports on the topic "Diffusion controlled reactions"

1

Redner, Sidney. Kinetics of Diffusion-Controlled Reactions. Fort Belvoir, VA: Defense Technical Information Center, August 1989. http://dx.doi.org/10.21236/ada212161.

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Rehm, Ronald G., Howard R. Baum, and Daniel W. Lozier. Diffusion-controlled reaction in a vortex field. Gaithersburg, MD: National Bureau of Standards, 1987. http://dx.doi.org/10.6028/nbs.ir.87-3572.

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Rehm, Ronald R., Howard R. Baum, Hai C. Tang, and Daniel W. Lozier. Finite-rate diffusion-controlled reaction in a vortex:. Gaithersburg, MD: National Institute of Standards and Technology, 1992. http://dx.doi.org/10.6028/nist.ir.4768.

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Siekhaus, W. Reaction Between Thin Gold Wires And Pb-Sn-In Solder (37.5%, 37.5%, 25%), Part C. A Comprehensive Model Of The Reaction Inside The Solder Mounds In Both The Interface Controlled Regime And The Diffusion-Controlled Regime. Office of Scientific and Technical Information (OSTI), August 2012. http://dx.doi.org/10.2172/1084719.

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5

Siekhaus, W. Reaction Between Thin Gold Wires and Pb-Sn-In Solder (37.5%, 37.5%, 25%), Part C. A comprehensive Model Of The Reaction Inside the Solder Mounds In Both The "Interface Controlled Regime" and The "Diffusion-Controlled" Regime During Long-Term Exposure. Office of Scientific and Technical Information (OSTI), February 2011. http://dx.doi.org/10.2172/1068279.

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