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Steuer, Haiko. "Thermodynamical properties of a model liquid crystal." [S.l.] : [s.n.], 2004. http://edocs.tu-berlin.de/diss/2004/steuer_haiko.htm.
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Pracný, Vladislav. "Neural network based shock absorber model with a thermodynamical coupling : experiment, modeling and vehicle simulation /." Aachen : Shaker, 2009. http://d-nb.info/994209967/04.
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Ramos, Luís Roberto. "Propriedades termodinâmicas do Modelo de Falicov-Kimball de duas impurezas sem spin." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-03062014-103216/.
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Neste trabalho estudamos o modelo de Falicov-Kimball, que descreve duas impurezas sem spin, localizadas e hibridizadas com elétrons de condução de um metal hospedeiro, o que faz com que a valência flutuante seja algo intrínseco do modelo. Os estados de condução são, também, espalhados eletrostaticamente quando uma carga estiver presente nos níveis locais das impurezas. O estudo foi realizado através do cálculo de propriedades termo dinâmicas do modelo, mais precisamente, da análise do calor específico e da suscetibilidade de carga em função da temperatura e para vários parâmetros diferentes do modelo. Para a obtenção do espectro de energias do Hamiltoniano que descreve o modelo, do qual as propriedades termodinâmicas são obtidas, utilizamos o Grupo de Renormalização Numérico com dois parâmetros de discretização. Em nossos estudos, mostramos alguns resultados que vão além da usual aproximação que projeta todos os momentos no nível de Fermi. Começamos nosso estudo da termodinâmica do modelo analisando regiões do espaço de parâmetros onde o Hamiltoniano toma-se mais simples (regiões onde não há hibridização ou espalhamento eletrostático) e, então, interpretações mais simples dos dados são possíveis. Verificamos, por exemplo, que quando a hibridização é diferente de zero o sistema se comporta como líquido de Fermi para temperaturas indo à zero. Para algumas escolhas de parâmetros o sistema tem o comportamento de férmions pesados. Outro ponto a se destacar é que a razão de Wilson, definida aqui como a divisão da suscetibilidade de carga pelo calor específico, tem o valor universal R = 1, quando a hibridização está presente.In this work, we study the Falicov-Kimball model with two localized spinless impurities hybridized with conduction electrons of a host metal, therefore, valence fluctuation is intrinsic to the model. The conduction states are also electrostatically scattered whenever a charge is present em the local levels of the impurities. The study was realized computing thermodynamics properties of the model, more specifically, we analyze the temperature dependent specific heat end charge susceptibility for many different parameters of the model. The Numerical Renormalization Group with two discretization parameters is used to obtain the spectrum of the model, from what the thermodynamics is obtained. We discuss the importance of going beyond the usual approximation that projects all moment at the Fermi Level. We begun our study of the thermodynamical properties analyzing values of the parameters space, where the model becomes quadratic (that is, where hybridization or Coulomb scattering are absent), and thus simple interpretations of the data are possible. We verified, for example, that for non-zero hybridization, the system shows Fermi liquid behavior at low temperature. The Wilson ratio, defined here with the charge susceptibility instead of magnetic one, has the universal value R = 1, whenever the hybridization is present. For some choices of the model parameters the model behaviors like heavy fermion.
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Pracný, Vladislav [Verfasser]. "Neural network-based shock absorber model with a thermodynamical coupling : Experiment, modeling and vehicle simulation / Vladislav Pracny." Aachen : Shaker, 2009. http://d-nb.info/1161302549/34.
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Lima, Washington Luiz Carvalho. "Assimetria partícula-buraco no modelo de Kondo de duas impurezas." Universidade de São Paulo, 1997. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-07012009-093355/.
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Este trabalho tem como objetivo estudar as propriedades termodinâmicas do Hamiltoniano Kondo de duas impurezas. Desenvolvemos uma extensão da técnica do grupo de renormalização numérico (GRN) que permite diagonalizar o modelo Kondo de duas impurezas convencional preservando a sua assimetria partícula-buraco. Essa assimetria elimina o ponto crítico, com propriedades de líquido não de Fermi, encontrado dez anos atrás em trabalhos que estudaram o modelo simétrico usando o GRN ou a invariância conforme. Nossos resultados para a susceptibilidade, o calor específico e a defasagem da banda de condução em T = 0 mostram uma dependência contínua com a razão I/kbTk, onde I é a interação RKKY e Tk é a temperatura de Kondo. Esses resultados contrastam com os do Hamiltoniano simétrico que apresenta uma divergência no calor específico e uma descontinuidade na defasagem para o ponto crítico I/kbTk ~ 2.2. Calculamos, também, a dependência térmica da susceptibilidade magnética das impurezas. Nossas curvas são qualitativamente equivalente às encontradas num cálculo recente do GRN no modelo simétrico e confirmam os resultados qualitativos, obtidos no início dos anos 80, baseados na técnica de \"scaling\" perturbativos: (i) Para | I | << kbTk a susceptibilidade magnética por impureza é idêntica à de uma impureza isolada. (ii) Para I >> kbTk (interação RKKY antiferromagnética) as impurezas formam um estado fundamental singleto desacoplado da banda de condução. (iii) Para -I >> kbTk (acoplamento RKKY ferromagnético), com o decréscimo da temperatura, as impurezas se acoplam inicialmente num estado tripleto, cujo momento efetivo é, então, compensado por um efeito Kondo de dois estágios. Para confirmar essa interpretação dos resultados numéricos, apresentamos expressões fenomenológicas que ajustam muita bem a susceptibilidade calculada para os regimentos quais as energias características do sistema dividem o eixo de temperatura.This thesis studies the thermodynamical properties of the two-impurity Kondo Hamiltonian. Our generalized numerical renormalization-group approach maintains the particle-hole asymmetry found in the conventional model, which asymmetry washes out the critical point with non-Fermi liquid properties discovered ten years ago in numerical and analytical studies of the symmetric model. Our computation of the low-temperature susceptibility, linear coefficient of the specific heat, and ground-state phase shifts shows smooth dependencies on the ratio I/kbTk where I is the RKKY interaction and Tk the Kondo temperature. This contrasts with the symmetric Hamiltonian, which yields a specific-heat singularity and a sharp phase-shift discontinuity at the critical ratio I/kbTk ~ 2.2. We have also computed the temperature dependence of the impurity magnetic susceptibility. Our curves show the qualitative features encountered in a recent numerical renormalization-group study of the symmetric model and confirm the predictions of a scaling analysis carried out in the early 80\'s: (i) For | I | << kbTk the per-impurity susceptibility mimics that of an isolated impurity. (ii) For I >> kbTk (antiferromagnetic RKKY interaction), the impurities tend to lock into a ground-state singlet decoupled from the conduction electrons. (iii) For -I >> kbTk (ferromagnetic RK KY coupling), as the temperature decreases, the impurities first lock into a triplet, whose effective moment is then screened in a two-stage Kondo effect. To further confirm this interpretation of the numerical results, we present phenomenological expressions that fit well the calculated susceptibilities for each regime into which the characteristic energy scales divide the temperature axis.
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Belkhiri, Madeny. "Plasma out of thermodynamical equilibrium : influence of the plasma environment on atomic structure and collisional cross sections." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112268/document.
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Dans les plasmas chauds denses, la distribution spatiale des électrons libres et des ions peut affecter fortement la structure atomique. Pour tenir compte de ces effets, nous avons implémenter un potentiel plasma fond´ sur le modèle d’un gaz d’électron uniforme et sur une approche de type Thomas-Fermi dans le Flexible Atomic Code (FAC). Ce code a été utilisé, pour obtenir les énergies, les fonctions d’onde, et les taux radiative modifiés par l’environnement plasma. Dans des ions hydrogénoides, les résultats numériques ont été comparés avec succès à un calcul analytique basé sur la théorie des perturbations du premier ordre. Dans le cas des ions multi-électronique, on observe un décalage des niveaux, en accord avec d’autre calcul récent. Diverses méthodes pour les calculs de section efficace de collision sont examinées. L’influence de la densité du plasma sur ces sections est analysée en détail. Certaines expressions analytiques sont propos´es pour les ions hydrogénoides comme dans la limite où l’approximation de Born ou Lotz s’applique et sont comparés aux résultats numériques du code de FAC. Enfin, à partir de ce travail, nous étudions l’influence de l’environnement de plasma sur notre modèle collisionel-radiatif nommé -Foch-. En raison de cet environnement, la charge moyenne du plasma augmente, ceci est principalement due a l’abaissement du continuum. Nous observons également, le décalage des raies sur les spectres d’émission lié-lié. Un bon accord est trouvé entre notre travail et les données expérimentales sur un plasma de titaneIn hot dense plasmas, the free-electron and ion spatial distribution may strongly affect the atomic structure. To account for such effects we have implemented a potential correction based on the uniform electron gas model and on a Thomas-Fermi Approach in the Flexible Atomic Code (FAC). This code has been applied to obtain energies, wave-functions and radiative rates modified by the plasma environment. In hydrogen-like ions, these numerical results have been successfully compared to an analytical calculation based on first-order perturbation theory. In the case of multi-electron ions, we observe level crossings in agreement with another recent model calculation. Various methods for the collision cross-section calculations are reviewed. The influence of plasma environment on these cross-sections is analyzed in detail. Some analytical expressions are proposed for hydrogen-like ions in the limit where Born or Lotz approximations apply and are compared to the numerical results from the FAC code. Finally, from this work, we study the influence of the plasma environment on our collisional-radiative model so-called -Foch-. Because of this environment, the mean charge state of the ions increases. The line shift is observed on the bound-bound emission spectra. A good agreement is found between our work and experimental data on a Titanium plasma
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Padilha, Igor Tavares. "Estudo das propriedades termodinâmicas no modelo de Ising aleatoriamente decorado com interações competitivas." Universidade Federal do Amazonas, 2006. http://tede.ufam.edu.br/handle/tede/3464.
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In this work we will study the thermodynamics properties of the quenched decorated Ising model with competitive interactions through the effective field theory (EFT) of a one-spin cluster. The quenched decorated Ising model with competitive interactions is here used to describe the thermodynamics properties of the cooper-based oxide superconductors compounds in the insulating phase (antiferromagnetic). The model consists of planes in which the nodal spins interact antiferromagnetically (JA < 0) with their nerest-neighbors and ferromagnetically (JF > 0) with the spins that decorated the bonds, which are quenched randomly distributed over the twodimensional lattice. The planes interact antiferromagnetically with weak exchange interaction (i.e., JA´=λ JA , λ=10-5 ). By using the framework of an effective-field theory, based in the differential operator technique, we discuss beyond thermodynamics properties the antiferromagnetic-phase stability limit in the temperature-decorated bond concentration space (T-p), for λ =10-5 and various values of frustration parameter (α= JA / JF), magnetic field (H) and concentration parameter (p). For certain range of the parameter α we observe a reentrant behavior in low-temperature what it reflects in the properties behavior itself.
Neste trabalho estudaremos as propriedades termodinâmicas do modelo de Ising decorado de forma quenched (temperada) com interações competitivas através da teoria de campo efetivo (EFT) com aglomerado de um spin. O modelo de Ising decorado com interações competitivas aqui é utilizado para descrever as propriedades termodinâmicas dos compostos supercondutores baseados em planos de Cobre-Oxigênio em sua fase isolante (antiferromagnética). O modelo consiste em planos nos quais os spins nodais interagem antiferromagneticamente (JA < 0) com seus primeiros vizinhos, e ferromagneticamente (JF > 0) com os spins decoradores, os quais são distribuídos aleatoriamente de forma quenched sobre uma rede bidimensional. Os planos interagem antiferromagneticamente com uma fraca interação de troca (i.e., JA´=λ JA , λ=10-5). Utilizando o formalismo da teoria do campo efetivo, baseado na técnica do operador diferencial, discutiremos além das propriedades termodinâmicas do sistema o limite de estabilidade antiferromagnética no diagrama temperatura e concentração (T-p), para λ=10-5 e vários valores do parâmetro de frustração (α=JA / JF), campo magnético (H) e parâmetro de concentração (p). Observamos que para certos intervalos de valores do parâmetro α, o sistema apresenta um comportamento reentrante em baixas temperaturas o que se reflete nas propriedades do sistema.
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Ozkan, Ibrahim Ali. "Thermodynamic model for associating polymer solutions." Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-05042004-142825/unrestricted/ozkan%5Fibrahim%5Fa%5F200408%5Fphd.pdf.
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Thesis (Ph. D.)--School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 2005. Directed by Amyn S. Teja.Dr. Thomas H. Sanders, Committee Member ; Dr. Peter J. Ludovice, Committee Member ; Dr. J. Carson Meredith, Committee Member ; Dr. William J. Koros, Committee Member ; Dr. Amyn S. Teja, Committee Chair. Includes bibliographical references.
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Kopečný, Lukáš. "McKibbenův pneumatický sval - modelování a použití v hmatovém rozhraní." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-233458.
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This work describes exceptional properties of McKibben pneumatical muscle and introduces its state-of-the-art model. The mathematical model is extended especially in a field of a thermodymical behavior. A new model applies a method used for describing of a thermodynamical behavior of pneumatic cylinders until now. This method is significantly upgraded to fit a muscle behavior, particularly by considering a heat generated by a muscle internal natural friction. The model is than verified and discussed with a real system. The haptic part introduces a development and design of a haptic glove interface for the use in robotics, especially in telepresence, or in VR. The force and touch feedback is provided by Pneumatic Muscles controlled by an open loop algorithm using the introduced mathematical model. The design is light and compact.
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Green, E. "Thermodynamics of melting in model mantle compositions." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599659.
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A set of thermodynamic models suitable for mantle mineral phases, accompanied by a mafic melt model, has been calibrated in the system CaO-MgO-Al2O3-SiO2 (CMAS) and its subsystems, over the pressure range 0.50 kbar. The models are able to reproduce phase assemblages and reactions observed by experiment. Having a fundamentally thermodynamic form, they can be interpolated reliably between the pressures, temperatures and compositions of the experiments. The models may be used with the phase equilibrium calculation software THERMOCALC, and they incorporate end-members from its internally consistent dataset for greater rigour of calibration. The mafic melt model was the focus of model development. It takes a simple regular solution formulation, in common with many of the solid solution models used in THERMOCALC. However a number of modifications had to be made in order to attain a suitably flexible model melt, since natural mafic liquids cover a very much larger compositional range than any solid solution, and have many more degrees of structural freedom. Faced with these intrinsic problems in melt modelling, the approach taken has been to calibrate the model first in small systems of one, two and three components, combining these to make larger systems. Such an approach leads to a more comprehensive model calibration, exploiting the information available in very simple systems about liquid behaviour. In the CMAS system, model fit is excellent in the pressure range 15-50 kbar. During the fitting process, a case was made for applying a pressure adjustment of -15% to one group of calibration experiments. If this is appropriate, model calculations reproduce the melting reactions well within the experimental error of ±10°C, otherwise, the reactions are calculated at temperatures up to 50°C too high. Calculated phase relations at lower pressure require further attention. Liquid and solid solution compositions are difficult to determine experimentally and probably have large unquantified errors; calculated values typically match those of the calibration experiments to within 20%. The models are able to mimic subtle features of experimental melting relations in CMAS, mostly arising from the interaction of clinopyroxene solid solution with liquid. A preliminary extension of the models was made into the system Na2O-CaO-FeO-MgO-Al2O3-Fe2O3-SiO2-Cr2O3 (NCFMASCrO), producing a reasonable fit to experimentally determined oxide trends. A set of sample calculations produced with the CMAS models is presented, demonstrating the modelling of fractional and batch melting and crystallisation. Further calculations take the form of pseudosections: maps of the phase assemblages in P-T space drawn for a single bulk composition, and contoured for phase composition. Pseudosections are powerful means of investigating thermodynamic equilibrium in a rock, since they incorporate the natural constraint of bulk composition – however they cannot produce meaningful calculations without sophisticated and reliable thermodynamic phase models. The propagation of uncertainties in fitted model parameters into pseudosection calculations is explored for the first time using Monte Carlo techniques.
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Potapova, Julia. "Melting ice with salt - a thermodynamic model." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bygg, anlegg og transport, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18473.
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Road salting forms an essential element in the winter maintenance of roads. With salt usage increasing there is a need for an optimizing of salt practices. This master thesis is focused on the melting of ice below 0°C with use of salt (the de-icing process). The use of dissolved salt (Sodium Chloride) is considered only, and the melting process that takes place in an adiabatic system. The increased understanding of the physics of ice melting will hopefully contribute into optimizing de-icing operations. The thermodynamics of ice melting by salt has been studied by developing a calculation model, which can be used to predict the final temperature of an “ice-salt solution” system and the amount of melted ice, for a given salt solution.Five solutions with different salt concentrations (5, 10, 15, 20 and 23 w%) have been experimentally tested to determine the temperature change inside the reactor caused by adding of a certain amount of ice to the solution. The calculated and experimentally determined values of final temperature (T_f) have been further compared to identify the discrepancy in obtained results and to which extent the developed model is theoretically applicable. The comparison between the model and experiments has shown that the model was able to predict the final temperature of the “ice-salt solution” system with high precision throughout the investigated temperature range between -16°C and 0°C. In 89% of the cases the error between the determined results lies within temperature interval ± 1°C. The model has showed to have a better performance and gives lower level of discrepancies between the calculated and measured results when the solution has reached its ice melting capacity, i.e. when unmelted ice fractions are present in salt solution. In order for decrease the level of existent uncertainties and obtain more accurate results, it is recommended to incorporate the omitted value for heat loss in the developed model and to conduct all experiments in a cold room under constant, low temperature conditions.
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Tagner, Nikita, and Arian Abedin. "Thermodynamic model for power generating gas turbines." Thesis, KTH, Energiteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-170917.
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Gasturbiner används i en mängd olika sammanhang, från kraftgenerering till flygplansmotorer. Prestandan hos gasturbiner beror på omgivningstillstånd såsom temperatur och tryck. Gasturbintillverkare förser ofta vissa parametrar, exempelvis uteffekt och massflöde i avgaserna vid väldefinierade standard tillstånd, ofta refererade till som ISO-tillstånd. På grund av det tidigare beskrivna beroendet är det nödvändigt för köpare att kunna förutspå prestandan vid platsen där gasturbinen ska användas. I denna studie har en termodynamisk modell för kraftgenerande gasturbiner konstruerats. Modellen förutspår uteffekten vid full belastning för varierande omgivningstemperatur och omgivningstryck. Den konstruerade modellen har jämförts med prestandadata från Siemens egna modeller, vid varieande temperatur. Prestandadata för varierande tryck kunde inte erhållas. Den konstruerade modellen är konsekvent med Siemens modeller inom vissa temperaturintervall vars längd beror på den utvärderade gasturbinens storlek. För mindre gasturbiner är temperaturintervallet för vilken den konstruerade modellen är konsekvent längre än för större gasturbiner.Gas turbines are used for a variety of purposes ranging from power generation to aircraft engines. Their performance is dependent on ambient conditions such as temperature and pressure. Gas turbine manufacturers often provide certain parameters like power output and exhaust mass flow at well-defined standard conditions, usually referred to as ISO-conditions. Due to the aforementioned dependency, it is necessary for buyers to be able to predict gas turbine performance at their chosen site of operation. In this study, a thermodynamic model for power generating gas turbines has been constructed. It predicts the power output at full load for varying ambient temperature and pressure. The constructed model has been compared with performance data taken from Siemens own models for varying temperatures. No performance data for varying pressures could be obtained. The constructed model is consistent with the Siemens models within certain temperature intervals, which differ depending on the size of the gas turbine. For smaller gas turbines, the interval where the constructed model is consistent is greater than for larger gas turbines.
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Ou, Zhaoyang. "An association model for specific-interaction effects in random copolymer solutions." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/9140.
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Tamim, Jihane. "A continuous thermodynamics model for multicomponent droplet vaporization." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/mq20955.pdf.
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Taylor, Andrew James David. "The Capillary-Centric Model of Coupling-As-Thermodynamics." Thesis, North Dakota State University, 2015. https://hdl.handle.net/10365/27648.
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Models of ventricular-arterial coupling (VAC) have historically described the heart as a
function of its energetic interaction with the arterial system. However, these models either
represent the dynamic, adaptive cardiovascular system (CVS) in isolation or sacrifice cardiac
mechanics to use simplified, time-averaged values across the cardiac cycle. In this thesis a
facsimile CVS is constructed that characterizes ventricular-arterial interactions with intact
cardiac mechanics as a function of whole-body thermo-fluid homeostatic regulation.
Simulation results indicate proportional-integral (PI) control of heart rate and arterial
resistance is conditionally sufficient to maintain body temperature during square-wave
exercise, but further elements may be required to mimic genuine physiological responses.
These simulations of the primitive model lay the framework of capillary-centric VAC through
the perspective of coupling-as-thermodynamics.
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Gerogiokas, Georgios. "Quantitative models of biomolecular hydration thermodynamics." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/14181.
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This thesis explores the use of cell theory calculations to characterise hydration thermodynamics in small molecules (cations, ions, hydrophobic molecules), proteins and protein-ligand complexes. Cell theory uses the average energies, forces and torques of a water molecule measured in its molecular frame of reference to parameterise a harmonic potential. From this harmonic potential analytical expressions for entropies and enthalpies are derived. In order to spatially resolve these thermodynamic quantities grid points are used to store the forces, torques, and energies of nearby waters which giving rise to the new grid cell theory (GCT) model. GCT allows one to monitor hydration thermodynamics at heterogeneous environments such as that of a protein surface. Through an understanding of the hydration thermodynamics around the protein and particularly around binding sites, robust protein-ligand scoring functions are created to estimate and rank protein-ligand binding affinities. GCT was then able to retrospectively rationalise the structure activity relationships made during lead optimisation of various ligand-protein systems including Hsp90, FXa, scytalone dehydratase among others. As well as this it was also used to analyse water behaviour in various protein environments with a dataset of 17 proteins. The grid cell theory implementation provides a theoretical framework which can aid the iterative design of ligands during the drug discovery and lead optimisation processes, and can provide insight into the effect of protein environment to hydration thermodynamics in general.
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Walters, Joseph D. "Optimization and Thermodynamic Performance Measures of a Class of Finite Time Thermodynamic Cycles." PDXScholar, 1990. https://pdxscholar.library.pdx.edu/open_access_etds/1186.
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Modifications to the quasistatic Carnot cycle are developed in order to formulate improved theoretical bounds on the thermal efficiency of certain refrigeration cycles that produce finite cooling power. The modified refrigeration cycle is based on the idealized endoreversible finite time cycle. Two of the four cycle branches are reversible adiabats, and the other two are the high and low temperature branches along which finite heat fluxes couple the refrigeration cycle with external heat reservoirs.
This finite time model has been used to obtain the following results: First, the performance of a finite time Carnot refrigeration cycle (FTCRC) is examined. In the special case of equal heat transfer coefficients along heat transfer branches, it is found that by optimizing the FTCRC to maximize thermal efficiency and then evaluating the efficiency at peak cooling power, a new bound on the thermal efficiency of certain refrigeration cycles is given by $\epsilon\sb{m} = (\tilde\tau\sp2\sb{m}\ (T\sb{H}/T\sb{L}) - 1)\sp{-1},$ where $T\sb{H}$ and $T\sb{L}$ are the absolute high and low temperatures of the heat reservoirs, respectively, and $\tilde\tau\sb{m}=\sqrt{2}$ + 1 $\simeq$ 2.41 is the dimensionless cycle period at maximum cooling power.
Second, a finite time refrigeration cycle (FTRC) is optimized to obtain four distinct optimal cycling modes that maximize efficiency and cooling power, and minimize power consumption and irreversible entropy production. It is found that to first order in cycling frequency and in the special symmetric case, the maximum efficiency and minimum irreversible entropy production modes are equally efficient. Additionally, simple analytic expressions are obtained for efficiencies at maximum cooling power within each optimal mode. Under certain limiting conditions the bounding efficiency at maximum cooling power shown above is obtained.
Third, the problem of imperfect heat switches linking the working fluid of an FTRC to external heat reservoirs is studied. The maximum efficiency cycling mode is obtained by numerically optimizing the FTRC. Two distinct optimum cycling conditions exist: (1) operation at the global maximum in efficiency, and (2) operation at the frequency of maximum cooling power. The efficiency evaluated at maximum cooling power, and the global maximum efficiency may provide improved bench-mark bounds on thermal efficiencies of certain real irreversible refrigeration cycles.
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Coram, Geoffrey J. (Geoffrey John) 1971. "Thermodynamically valid noise models for nonlinear devices." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/29886.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.Includes bibliographical references (p. 209-221).
Noise has been a concern from the very beginning of signal processing and electrical engineering in general, although it was perhaps of less interest until vacuum-tube amplifiers made it audible just after 1900. Rigorous noise models for linear resistors were developed in 1927 by Nyquist and Johnson [1, 2]. However, the intervening years have not brought similarly well-established models for noise in nonlinear devices. This thesis proposes using thermodynamic principles to determine whether a given nonlinear device noise model is physically valid. These tests are applied to several models. One conclusion is that the standard Gaussian noise models for nonlinear devices predict thermodynamically impossible circuit behavior: these models should be abandoned. But the nonlinear shot-noise model predicts thermodynamically acceptable behavior under a constraint derived here. This thesis shows how the thermodynamic requirements can be reduced to concise mathematical tests, involving no approximations, for the Gaussian and shot-noise models. When the above-mentioned constraint is satisfied, the nonlinear shot-noise model specifies the current noise amplitude at each operating point from knowledge of the device v - i curve alone. This relation between the dissipative behavior and the noise fluctuations is called, naturally enough, a fluctuation-dissipation relation. This thesis further investigates such FDRs, including one for linear resistors in nonlinear circuits that was previously unexplored. The aim of this thesis is to provide thermodynamically solid foundations for noise models. It is hoped that hypothesized noise models developed to match experiment will be validated against the concise mathematical tests of this thesis. Finding a correct noise model will help circuit designers and physicists understand the actual processes causing the noise, and perhaps help them minimize the noise or its effect in the circuit.
by Geoffrey J. Coram.
Ph.D.
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Moosbrugger, John C. "A rate-dependent bounding surface model for nonproportional cyclic viscoplasticity." Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/16353.
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Burgess, Sarah Elisabeth. "Membrane transport studies : novel methods, model systems and thermodynamics." Thesis, University of Greenwich, 2005. http://gala.gre.ac.uk/6121/.
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The work in this thesis shows that it is possible to design a diffusion cell which will allow access to the flux and lag time of a permeant without the need for invasive sampling and that this novel cell is both sensitive and reproducible. It was also shown that the cell could be used in conjunction with both simple model membranes and more complex biological membranes, namely the epidermis. From the data achieved from the cell it was possible to derive a series of equations which allowed access to thermodynamic parameters such as ?H, ?G and ?S. An extension of this calculational approach revealed that manipulation of the van’t Hoff isochore, under the condition where enthalpy is constant over the temperature range, it should be possible to calculate the partition coefficient. Ultimately these parameters can be used in the description of structure activity relationships. The systems described in this thesis are of a complex biological nature consequently the returned data reflect this complexity. In order to utilise the data to their full potential some method for dealing with this complexity was sought. One approach widely discussed in the literature is that of chemometric analysis or soft modelling. Initial studies into the use of chemometric analysis proved positive for the data presented in this thesis, and suggested that formulation contributions from components with close absorbance maxima could be separated.
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Piazzoni, Antonio Sebastiano. "Coupling thermodynamic mineralogical models and mantle convection." Diss., lmu, 2007. http://nbn-resolving.de/urn:nbn:de:bvb:19-91854.
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Piazzoni, Antonio Sebastiano. "Coupling thermodynamic mineralogical models and mantle convection." kostenfrei, 2008. http://edoc.ub.uni-muenchen.de/9185/.
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Rossi, Marco, Thomas Wallmersperger, Jorge Alejandro Ramirez, and Paola Nardinocchi. "jz Thermodynamically consistent electro-chemo-mechanical model for polymer membranes." SPIE, 2018. https://tud.qucosa.de/id/qucosa%3A35160.
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Nafion membranes, are polymeric thin films widely employed in micro-batteries and fuel cells. These devices are expected to play a key role in the next generation energy systems for use in vehicles as a replacement to combustion engines. In fact, a minimum environmental impact is guaranteed by reduced carbon dioxide emissions. It is usually complicated to investigate the behavior of thin membranes through experiments. Therefore, numerical simulations are carried out in order to enable a better understanding of the phenomena and of the multi-field couplings occurring in polymeric membranes.
A continuum-based, three-dimensional and electro-chemo-mechanical (ECM) model for a hydrated polymer membrane is presented. Different effects are taken into account: (i) mechanics, (ii) water uptake, (iii) ion transport, and (iv) electrostatics. The dissipation inequality drives the choice of the suitable constitutive equations of the multi-physics theory. In the mechanical field, an additive decomposition of the deformation gradient in (i) a distortion part, related to the ion motion, and (ii) an elastic part, is assumed. The multi-field model is numerically solved within the finite element framework. Time-dependent simulations are performed by using the commercial tool COMSOL Multiphysics. Furthermore, two closed form solutions are obtained by using (i) a one-dimensional reduced model and (ii) an approach based on the bar theory with an electro-chemical distortion field.
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Kerala, Varma Vipin [Verfasser]. "Critical, statistical, and thermodynamical properties of lattice models / Vipin Kerala Varma." Bonn : Universitäts- und Landesbibliothek Bonn, 2013. http://d-nb.info/1045276502/34.
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van, Bloemen Waanders Paul Nicholas. "Thermodynamic Based Model Eliciting Activities For Undergraduate Mechanical Engineering Education." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/555.
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Undergraduate engineering education is designed to prepare students for their careers. The rise of technology in modern engineering allows for a shift in the way undergraduates are prepared for the modern workplace. Model Eliciting Activities (MEAs) allow students to think critically about their own work and allow instructors to analyze the students’ problem solving methods. To ensure that new MEAs are as effective as possible they are subject to six basic principles: model construction, reality, generalizability, self-assessment, model documentation, and effective prototype.
This document focuses on evaluating new MEAs for their adherence to the six principles from an instructor's and student's perspective. Four new MEAs were created and implemented in the school year of 2009-2010. Two of the MEAs were designed to target a sophomore level thermal engineering class. The first was an introduction to data acquisition systems (DAQs) and the second was an introduction to strain gauges. These two MEAs were tested on two separate classes and were evaluated strictly from an instructor’s perspective. The two MEAs met their objectives for introducing DAQs and strain gauges respectively and managed to reinforce existing ideas at the same time. However, the MEA about DAQs appeared to adhere to all of the six principles while the MEA about strain gauges did not.
The other two MEAs were designed for an introductory thermodynamics course. The students' solutions to the MEAs were analyzed to determine the MEAs' effectiveness as well as how well they follow the six principles of MEAs. The first MEA was centered around a supermileage vehicle and asks the students to model an engine cycle from a P-V diagram of a real engine cycle. Careful analysis of the solutions that the students turned in found that the MEA did not provide a way for the students to verify their models. It was also found that students were learning about isothermal and adiabatic curves on their own which satisfied the main goal of the MEA which was to familiarize the students with simple processes. The second activity was based upon an industrial process that delivered waste energy into a river and the students were asked to model a power plant that could use the energy and lower the amount of heat dumped into the river. The objective was to get the students to think about entropy and how much energy can be salvaged in the system. A vast majority of students enjoyed the activity saying it was well worth their time, while only half of the students identified that entropy had some part in the MEA. Whether or not the objective to get the students to associate usable energy with entropy production was accomplished is uncertain. What was determined was that some students were unable to check their answers and they developed models that were inaccurate. From this observation it was seen that the self assessment principle was not being properly addressed.
All of the developed MEAs satisfied their end goals of teaching the students the material that the MEA was developed around. The two most prominent issues were students misunderstanding the problem statement and students not being able to verify their models. These are important observations for these particular MEAs that were only possible through intensive analysis of the solutions from a student's perspective. The detailed analysis of the solutions using the six principles as a guideline provided insight to some of the problems students were having. For future work, these same MEAs could be improved upon and then analyzed again to see if the analysis is consistent and that the identified problems were corrected.
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Abutayeh, Mohammad. "Thermodynamic Model and the Controlling Variables of Phosphate Lattice Loss." Scholar Commons, 1999. https://scholarcommons.usf.edu/etd/1551.
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A thermodynamic model was developed based upon five equilibrium reactions to predict the limits of distribution of phosphates between the liquid and the solid phases in a reactor used to extract phosphoric acid from phosphate rock. A computer code was generated to carry out different simulations of the model using several inputs of temperatures and liquid phase sulfuric acid contents. Ideal Solution, Debye-Hückel, and Robinson-Guggenheim-Bates electrolyte activity coefficient models were employed alternately in each simulation to complete the thermodynamic model and the outputs were compared to one another.
Experimental data of equilibrium constants were regressed to adjust the values of ΔCp° and ΔH° used in the simulations to obtain a more accurate representation of the thermodynamic equilibrium. Results for ionic strength, liquid phase pH, and phosphate lattice loss were used to analyze temperature and liquid phase sulfuric acid content effects on the reacting system.
Completing the thermodynamic model with Ideal Solution and Debye- Hückel electrolyte activity coefficient models was found to bind all predictions of phosphate lattice loss. The model prediction of phosphate losses was found to give a lower bound to the real phosphate losses. Furthermore, decreasing temperature and increasing liquid phase sulfuric acid content was found to minimize phosphate lattice loss.
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SEDEQI, FAISAL. "High Temperature Co-Electrolysis Model for Sector Coupling : Thermodynamic and Detailed Models of Solid Oxide Electrolysis Cells and Systems." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-286048.
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The increased development of intermittent renewable energy supplies not only demands robust storage technology, but also alternative means to produce materials in ways to avoid fossil fuel consumption and make use of the increasing electricity supply. Power to gas (PtG) through solid oxide cell (SOC) co-electrolysis reactors provide an attractive manner to overcome both challenges. The performance of co-electrolysis reactors for sector coupling purposes was investigated through mathematical models at the stack and system level.The system level model involved the development of an ideal power to methane (PtM) system with no losses in the auxiliary units and ideal SOC operation. This model was used to determine the maximum achievable efficiencies independent of technology, for a co-electrolysis and steam electrolysis based PtM in two different schemes: atmospheric SOC with pressurised methanation reactor and equal pressure between the SOC and methanation reactor. The performance of the system was analysed through the exergy method for different operating temperatures and pressures. The system was designed to be completely coupled, where the heat generated by one process was usable for another. Functional exergy efficiency was one of the main performance criteria used for comparison. It was found that for an ideal system, co-electrolysis operation was marginally beneficial over steam electrolysis at the system level based on exergetic efficiency. This is further compounded when considering the product yield, where the co-electrolysis systems outperform the steam electrolysis systems significantly.The stack level model involved introducing a new modelling framework based on fundamental charge transfer interactions to modify a transient steam/𝐻𝐻2 based SOC reactor modelled with Modelica at the DLR. This also involved modifying the reversible potential model to account for co-electrolysis as well as novel implementation of the DGM for co-electrolysis. The model was validated against experimental results of steady state operation for 1.4bar, 4bar and 8bar and feed gas compositions of 60% steam, 30% 𝐶𝐶𝑂𝑂2 and 10% 𝐻𝐻2; and 45% steam, 45% 𝐶𝐶𝑂𝑂2 and 10% 𝐻𝐻2 by volume. The model results agree with the experimental results. Further analysis of the reactor under co-electrolysis operation was performed. The 𝐶𝐶𝑂𝑂2 consumption mechanism was investigated as well as various electrochemical and thermal phenomena, to understand the operating behaviour of co-electrolysis stacks and to obtain general trends in operation with different operating conditions. The SOC reactor model was also used to predict the reactor behaviour under elevated pressure operation outside of the validation scope. Elevated pressure operation reduced polarisation overpotentials and ohmic resistance due to higher methanation rate, this led to lower cell voltages at high operating current densities thereby reducing the power demand compared to the lower pressure operation. However, the higher methanation rate led to higher methane content in the reactor outlet.The trends with pressure and temperature in the stack model were used to determine the theoretical limits of the PtM system with a state-of-the-art reactor. Invariable efficiencies were applied to the auxiliary units as average efficiencies to consider a wide range of equipment efficiencies. The system performance was analysed for different operating temperatures, pressures, current densities, and stack active areas. System and stack performance increased with temperature, while pressure had marginal impact on system performance but reasonable impact on the stack performance especially for lower auxiliary unit efficiency. The system and stack performance decreased with current density while increasing the SOC area resulted in higher efficiencies to nearly ideal, for constant flow rates.The results of the models suggest that SOC based co-electrolysis reactors provide an attractive method for sector coupling purposes. The exergy method provided a broad method to analyse and compare different systems. More research is required, especially on the thermal aspects of SOC reactor and 𝐶𝐶𝑂𝑂2 consumption mechanisms in co-electrolysis reactors.Den ökade utvecklingen av förnybara energikällor kräver inte bara pålitlig lagringsteknik utan också alternativa sätt att producera material på sätt att undvika fossila bränsleförbrukningar och använda sig av den ökande elförsörjningen. Kraft till gas (PtG) genom fasta oxidceller (SOC) samelektrolysreaktorer ger ett attraktivt sätt att övervinna båda utmaningarna. Prestanda hos samelektrolysreaktorer för sektorkopplingsändamål undersöktes genom matematiska modeller på komponent- och systemnivå.Systemnivåmodellen involverade utvecklingen av ett idealiskt kraft-till-metan-system (PtM) utan förluster i hjälpenheterna och idealisk SOC-drift. Denna modell användes för att bestämma de maximalt uppnåbara effektiviteterna oberoende av teknik, för en samelektrolys och ångelektrolysbaserad PtM i två olika scheman: atmosfärisk SOC med trycksatt metaneringsreaktor och lika tryck mellan SOC och metaneringsreaktorn. Systemets prestanda analyserades genom exergimetoden för olika driftstemperaturer och tryck. Systemet var utformat för att vara helt kopplat, där värmen som genereras av en process kunde används vidare. Funktionell energieffektivitet var ett av de viktigaste prestationskriterierna som användes för jämförelse. Det visade sig att för ett idealiskt system var samelektrolysoperation marginellt fördelaktig jämfört med ångelektrolys på systemnivå baserat på exergetisk effektivitet. Detta blandas ytterligare när man överväger produktutbytet, där samelektrolyssystemen överträffar ångelektrolyssystemen avsevärt.Stacknivåmodellen involverade införandet av ett nytt modelleringsramverk baserat på grundläggande laddningsöverföringsinteraktioner för att modifiera en övergående ånga/𝐻𝐻2-baserad SOC-reaktor modellerad med Modelica vid DLR. Detta involverade också modifiering av den reversibla potentiella modellen för att ta hänsyn till samelektrolys samt ny implementering av DGM för samelektrolys. Modellen validerades mot experimentella resultat vid stationärt förhållande för 1,4bar, 4bar och 8bar och matargaskompositioner av 60% ånga, 30% 𝐶𝐶𝑂𝑂2 och 10% 𝐻𝐻2; och 45% ånga, 45% 𝐶𝐶𝑂𝑂2 och 10% 𝐻𝐻2 i volym. Modellresultaten överensstämmer med de experimentella resultaten. Ytterligare analys av reaktorn under samelektrolysoperation utfördes. 𝐶𝐶𝑂𝑂2-förbrukningsmekanismen undersöktes liksom olika elektrokemiska och termiska fenomen, för att förstå driftsbeteendet hos samelektrolysstaplar och för att få generella trender i drift med olika driftsförhållanden. SOC-reaktormodellen användes också för att förutsäga reaktorns beteende under förhöjd tryck utanför valideringsområdet. Förhöjt tryckdrift minskade polariseringsöverpotentialen och ohmskt motstånd på grund av högre metaneringshastighet, vilket ledde till lägre cellspänningar vid höga driftsströmtätheter, vilket minskade effektbehovet jämfört med lägre tryckoperation. Den högre metaneringshastigheten ledde emellertid till högre metanhalt i reaktorutloppet.Trenderna med tryck och temperatur i stackmodellen användes för att bestämma de teoretiska gränserna för PtM-systemet med en toppmodern reaktor. Konstanta verkningsgrader applicerades på hjälpenheterna som genomsnittliga verkningsgrad för att överväga ett brett spektrum av utrustningsverkningsgrad. Systemets prestanda analyserades med avseende på olika driftstemperaturer, tryck, strömtäthet och stack-aktiva områden. Systemets och stackens prestanda ökade med temperaturen, medan trycket hade marginell inverkan på systemets prestanda men rimlig inverkan på stackens prestanda, särskilt för de lägre hjälpaggregatens verkningsgrad. Systemets och stackens prestanda minskade med strömtätheten medan en ökning i SOC yta-resulterade i högre effektivitet till nästan idealisk för konstanta flödeshastigheter.Resultaten av modellerna antyder att SOC-baserade samelektrolysreaktorer ger en attraktiv metod för sektorkoppling. Exergimetoden gav en bred metod för att analysera och jämföra olika system. Mer forskning krävs, särskilt om de termiska aspekterna av SOC-reaktorn och 𝐶𝐶𝑂𝑂2-förbrukningsmekanismerna i samelektrolysreaktorer.
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Løvfall, Bjørn Tore. "Computer Realization of Thermodynamic Models Using Algebraic Objects." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for kjemisk prosessteknologi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-5326.
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The main focus of this thesis is to make thermodynamic models available for different computer programs on Windows, Linux and Unix computer platforms. In thermodynamic calculations, like phase or reaction equilibrium, the first and maybe higher order gradients of the thermodynamic functions are needed. The major challenge has been to enable higher order gradients (>2) of such functions, with symbolic precision, and without loosing the structure of the thermodynamic model equations. The solution to the problem lies in the novel RGrad language which enables commutative multidimensional array operations. The RGrad language introduced in this thesis is algebraically closed with respect to differentiation, which means that gradient calculations of arbitrary order are possible. The results are translated into ANSI C-code, interfaced with the user code by using a small and well defined C-interface. This interface has been demonstrated for Ruby and Matlab, but can easily be extended to other languages. The RGrad language has also been used to provide automatically generated Legendre transforms, with gradients. A few thermodynamic models generated with this methodology have been used to develop a new method for checking phase stabilities in multiphase, near-critical, phase equilibria. The method makes use of Legendre transforms to formulate the problem such that the same equations can be used for any number of phases, with any number of components. The phase stability test traverses the extensive thermodynamic space in the search for the most stable phase while keeping the chemical potentials the same as in the test phase. The final application discussed in this thesis deals with critical and tri-critical points. Legendre transforms are used to formulate stability criteria which are the same regardless of the number of components in the system. Furthermore, a Taylor expansion at the critical point has been developed to approximate the two-phase boundary of a system. The success of these calculations demonstrates that the gradient calculations are correct, and also that the automatic Legendre transform is implemented correctly.
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Cho, Kyoung Youn. "Nonequilibrium thermodynamic models and applications to hydrogen plasma." Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/17907.
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Yıldırım, Eda Didem Özerdem Barış. "A mathematical model of the human thermal system/." [s.l.]: [s.n.], 2005. http://library.iyte.edu.tr/tezler/master/makinamuh/T000421.pdf.
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Mokdad, Audrey. "Time-resolved thermodynamics studies of heme signaling proteins and model systems." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0003063.
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Stovall, Dawn Michele. "Thermodynamics of the Abraham General Solvation Model: Solubility and Partition Aspects." Thesis, University of North Texas, 2006. https://digital.library.unt.edu/ark:/67531/metadc5342/.
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Experimental mole fraction solubilities of several carboxylic acids (2-methoxybenzoic acid, 4-methoxybenzoic acid, 4-nitrobenzoic acid, 4-chloro-3-nitrobenzoic acid, 2-chloro-5-nitrobenzoic acid,2-methylbenzoic acid and ibuprofen) and 9-fluorenone, thianthrene and xanthene were measured in a wide range of solvents of varying polarity and hydrogen-bonding characteristics. Results of these measurements were used to calculate gas-to-organic solvent and water-to-organic solvent solubility ratios, which were then substituted into known Abraham process partitioning correlations. The molecular solute descriptors that were obtained as the result of these computations described the measured solubility data to within an average absolute deviation of 0.2 log units. The calculated solute descriptors also enable one to estimate many chemically, biologically and pharmaceutically important properties for the ten solutes studied using published mathematical correlations.
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Kemper, Andreas. "Transfermatrix-DMRG for dynamics of stochastic models and thermodynamics of fermionic models." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969450168.
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Hill, Alexandra. "Thermodynamic and Morphological Properties of Ceramide-1-Phosphate Model Monolayer Systems." Kent State University Honors College / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ksuhonors1291831964.
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Schulthess, Pascal. "Thermodynamic modeling explains the regulation of CYP1A1 expression in the liver." Doctoral thesis, Humboldt-Universität zu Berlin, Lebenswissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17454.
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Die vorliegende Studie präsentiert eine Analyse der Integration der AhR und Wnt/beta-catenin Signalwege in den CYP1A1 Promotor sowie den regulatorischen Einfluss der Promotorlogik auf die Genexpression. Experimentell wurde diese Analyse mithilfe 29 mutagener Reporterkonstrukte des humanen CYP1A1 Promotors durchgeführt. Ein mathematisches Modell, welches eine Repräsentation des Crosstalks der Signaltransduktionswege mit einer statistisch mechanischen Beschreibung der kombinatorischen Promotorbelegung kombiniert, komplementierte den experimentellen Ansatz. Unter zusätzlicher Zuhilfenahme von gut kontrollierbaren synthetischen Promotorkonstrukten fand ich heraus, dass nur jenes Dioxin-responsive Element das sich am nächsten am Transkriptionsstartpunkt befindet, die Promotorbelegung an die RNA Polymerase kommuniziert. Außerdem beobachtete ich, dass Transkriptionsfaktoren alleine mit Transkriptionsfaktoren interagieren die mit benachbarten Bindestellen assoziieren, d.h. Interaktionen überbrücken keine größeren Entfernungen. Der Modellierungsansatz ermöglichte zudem die erfolgreiche Vorhersage einer UND-Gatter-ähnlichen Integration der beiden Signalwege in den Promotor. Für die genomische Architektur des CYP1A1 Promotors konnte ich die Signifikanz der Zielbindestelle des Wnt/beta-catenin Signalwegs innerhalb des cis-regulatorischen Region demonstrieren. Mithilfe des Modells fand ich heraus, dass diese Bindestelle am stärksten und vielfältigsten mit den restlichen Transkriptionsfaktoren interagiert. Zusätzliche konnte, im Vergleich zu dem alles-oder-nichts UND-Gatter der synthetischen Konstrukte, eine sehr viel graduellere Antwort auf die Integration der beiden Signalwege aufgezeigt werden. Abschließend wurde das physiologisch zu beobachtende Expressionsmuster von dem Modell vorhergesagt und experimentell validiert.The study at hand presents an analysis of the integration of the AhR and the Wnt/beta-catenin signaling pathways into the CYP1A1 promoter as well as the regulatory influence of the promoter logic on gene expression. Experimentally, this analysis was conducted with the help of 29 mutant constructs of the human CYP1A1 promoter. I complemented this experimental approach with a set of mathematical models that combined a representation of the signaling crosstalk with a statistical mechanics description of the combinatorial promoter occupancy. With the help of well controllable synthetic promoter constructs I found that only the dioxin responsive element closest to the transcription start site communicates the promoter occupancy to the RNA polymerase. Furthermore, transcription factors only interact with transcription factors that associate with nearby binding sites, i.e., no long-distance binding was observed. The modeling approach subsequently enabled the successful prediction of an AND-gate-like integration of the two signaling pathways into the promoter. For the genomic architecture of the CYP1A1 promoter, I could demonstrate the importance of the Wnt/beta-catenin pathway target binding site within the cis-regulatory region. The model uncovered that this binding site is the strongest and most promiscuous interaction partner of the remaining transcription factors. In addition, a less switch-like response to the integration of the two signaling pathways as compared to the all-or-none AND-gate within the synthetic constructs could be demonstrated. And lastly, the physiological expression pattern in liver lobules could be successfully predicted by the model and experimentally verified.
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Abrahamowicz, Maria Izabela. "A thermodynamic and dynamic Lagrangian model for icebergs: a data-model intercomparison for the Southern Ocean." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18677.
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A Lagrangian dynamic and thermodynamic iceberg drift model was developed, coded and validated against observations. First, the model was used to create a climatology (1979-2000) of iceberg drift in the Southern Ocean. The simulation reproduced the main patterns of motion and the northernmost extent of Antarctic icebergs as inferred from satellite and ship observations. The model was then used to hindcast 29 giant iceberg drift tracks in what was the first study of an iceberg model ability to reproduce the motion of individual icebergs around the Antarctic continent on timescales of years. The shape and timing of twelve of the twenty-nine tracks was successfully modeled with a model error in the 0.9-50% range. In six cases, the shape of the observed drift track was reproduced but the timing was off, and in the remaining eleven simulation the icebergs moved in the wrong direction. The model error was found to be independent of simulation length suggesting that the error was due to inaccuracies in the forcing data rather than in the physics of the model. In particular, model performance deteriorated in coastal areas and in the southern portions of the Weddell and Ross sea, highlighting the need for higher resolution forcing data in these regions. The model accuracy would benefit from a better definition of the Antarctic coastline, a better representation of Katabatic winds off the continent and a forcing ocean model which would include a dynamic and thermodynamic sea-ice component.Un modèle Lagrangien dynamique-thermodynamique pour la dérive d'icebergs a été développé, codé et validé à l'aide d'observations. Premièrement, nous avons produit, à l'aide du modèle, une climatologie (1979-2000) de la dérive d'icebergs dans l'Océan du Sud. Les principales tendances du mouvement des icebergs simulés sont en accord avec les observations satellitaires et les mesures in-situ. Le modèle simule bien la limite septentrionale des icebergs d'Antarctique. Nous avons ensuite simulé vingt-neuf trajectoires individuelles d'icebergs géants. C'est la première fois qu'une telle étude est menée pour des icebergs observés autour de l'Antarctique et sur une échelle de plusieurs années. Dans douze cas, le tracé et le minutage de la trajectoire observée a été reproduit avec succès (erreur de 0.9-50%). Six simulations avaient des erreurs de temps mais non de trajet et dans les onze simulations restantes, l'iceberg a dérivé dans la mauvaise direction. Il a été établi que l'erreur du modèle était indépendante de la durée de la simulation, suggérant que l'erreur était due au champ de forçage plutôt qu'aux équations physiques du modèle. En particulier, une détérioration de la qualité des résultats a été observée dans les régions côtières et dans les parties sud des mers de Ross et de Weddell; soulignant ainsi le besoin d'améliorer le champ de forçage dans ces régions. D'autres moyens d'augmenter la précision du modèle seraient, entre autre, une meilleure définition de la géographie côtière de l'Antarctique, une meilleure représentation des vents catabatiques et un modèle océanique incluant une composante de glace dynamique et thermodynamique.
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Deng, Tʻai-ho. "Thermodynamic Properties of Nonelectrolyte Solutes in Ternary Solvent Mixtures." Thesis, University of North Texas, 1999. https://digital.library.unt.edu/ark:/67531/metadc279275/.
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The purpose of this dissertation is to investigate the thermodynamic properties of nonelectrolyte solutes dissolved in ternary solvent mixtures, and to develop mathematical expressions for predicting and describing that behavior in the solvent mixtures. Thirty-four ternary solvent systems were studied containing either alcohol (1-propanol, 2-propanol, 1-butanol, and 2-butanol), alkane (cyclohexane, heptane, and 2,2,4-trimethylpentane) or alkoxyalcohol (2-ethoxyethanol and 2-butoxyethanol) cosolvents. Approximately 2500 experimental measurements were performed. Expressions were derived from the Combined Nearly Ideal Multiple Solvent (NIMS)/Redlich-Kister, the Combined Nearly Ideal Multiple Solvent (NIMS)/Bertrand, Acree and Burchfield (BAB) and the Modified Wilson models for predicting solute solubility in ternary solvent (or even higher multicomponent) mixtures based upon the model constants calculated from solubility data in sub-binary solvents. Average percent deviation between predicted and observed values were less than 2%, documenting that these models provide a fairly accurate description of the thermodynamic properties of nonelectrolyte solutions. Moreover, the models can be used for solubility prediction in solvent mixtures in order to find the optimum solvent composition for solubilization or desolubilization of a solute. From a computational standpoint, the Combined Nearly Ideal Multiple Solvent/Redlich-Kister equation is preferred because the needed model constants can be calculated with a simple linear regressional analysis. Model constants for the Modified Wilson equation had to be calculated using a reiterative trial-and-error method. The C++ program for the Modified Wilson equation applied to ternary and heptanary solvent mixtures is attached.
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White, Thomas J. "Development of a parametric analysis microcomputer model for evaluating the thermodynamic performance of a reciprocating Brayton cycle engine." PDXScholar, 1987. https://pdxscholar.library.pdx.edu/open_access_etds/3794.
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In this thesis, applicable data from research on IC engines have been adapted to PACE engine designs. Data from studies on heat transfer, friction, and pressure losses, in particular, have been used. Certain parameters which define operation and design characteristics appear to influence PACE engine performance very strongly. Some of the more critical parameters, notably friction and heat transfer coefficients, must be determined experimentally if accurate model results are to be expected. Pressure ratio, compressor RPM, and maximum combustor temperature, the independent operating parameters, also have a dramatic effect on engine performance. Other design or operating characteristics and working fluid properties are not controlled independently. These are dictated by the engine physical design configuration and operation, ambient conditions, and choice of fuel.
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Seis, Christian. "Scaling laws in two models for thermodynamically driven fluid flows." Doctoral thesis, Universitätsbibliothek Leipzig, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-81228.
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In this thesis, we consider two models from physics, which are characterized by the interplay of thermodynamical and fluid mechanical phenomena: demixing (spinodal decomposition) and Rayleigh--Bénard convection. In both models, we investigate the dependencies of certain intrinsic quantities on the system parameters.
The first model describes a thermodynamically driven demixing process of a binary viscous fluid. During the evolution, the two components of the mixture separate into two domains of the different equilibrium volume fractions. One observes a clear tendency: Larger domains grow at the expense of smaller ones, and thus, the average domain sizes increases --- a phenomenon called coarsening. It turns out that two mechanisms are relevant for the coarsening process. At an early stage of the evolution, material transport is essentially mediated by diffusion; at a later stage, when the typical domain size exceeds a certain value, due to the viscosity of the mixture, a fluid flow sets in and becomes the relevant transport mechanism. In both regimes, the growth rates of the typical domain size obey certain power laws. In this thesis, we rigorously establish one-sided bounds on these growth rates via a priori estimates.
The second model, Rayleigh--Bénard convection, describes the behavior of a fluid between two rigid horizontal plates that is heated from below and cooled from above. There are two competing heat transfer mechanisms in the system: On the one hand, thermodynamics favors a state in which temperature variations are locally minimized. Thus, in our model, the thermodynamical equilibrium state is realized by a temperature with a linearly decreasing profile, corresponding to pure conduction. On the other hand, due to differences in the densities of hot and cold fluid parcels, buoyancy forces act on the fluid. This results in an upward motion of hot parcels and a downward motion of cold parcels. We study the dependence of the average upward heat flux, measured in the so-called Nusselt number, on the temperature forcing encoded by the container height. It turns out that the efficiency of the heat transport is independent of the height of the container, and thus, the Nusselt number is a constant function of height. Using a priori estimates, we prove an upper bound on the Nusselt number that displays this dependency --- up to logarithmic errors.
Further investigations on the flow pattern in Rayleigh--Bénard convection show a clear separation of length scales: Along the horizontal top and bottom plates one observes thin boundary layers in which heat is essentially conducted, whereas the large bulk is characterized by a convective heat flow. We give first rigorous results in favor of linear temperature profiles in the boundary layers, which indicate that heat is indeed essentially conducted close to the boundaries.
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Sohn, Munhee 1981. "An integrated geometric and thermodynamic performance model of the 2.670 Stirling Engine." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32788.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references (leaf 30).
2.670 is a required mechanical engineering class taught during the Independent Activities Period (IAP) at MIT in which each student constructs a Stirling Engine. For the most part, all of the engine parts are uniform, but if so desired, students are allowed to make design changes to certain parts in order to compete for the fastest engine at the end of the class. The research team in the MIT CADlab is working on an environment, called DOME, which makes it easy to link together simulations in different packages to perform integrated analysis and make them operable over the Internet. An integration environment has been created as a DOME project in which students can analyze and optimize the design of the 2.670 Stirling Engine. A thermodynamics model of the engine was created in Matlab and a parametric solid model was created in SolidWorks. Then, DOME was used to link the Matlab thermodynamic models to the Solidworks cad model so that when geometric parameters are changed one can see how this will affect engine performance. Students will be allowed to change the diameter and length of the displacer piston and see how it affects the work per cycle of the engine. In general, DOME was easy to learn how to use and the capabilities of web accessibility and the speed of design analysis and optimization was impressive. The future intention is that 2.670 students could use this integration environment to better analyze the 2.670 Stirling Engine.
by Munhee Sohn.
S.B.
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Ackler, Harold D. (Harold Dale) 1964. "Thermodynamic calculations and model experiments on thin intergranular amorphous films in ceramics." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10423.
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Blanco, Cavero Diego. "Assessment and optimization of the indicated cycle with a 0D thermodynamic model." Doctoral thesis, Universitat Politècnica de València, 2019. http://hdl.handle.net/10251/115934.
Full textAbstract:
[ES] Las amenazas a las que se enfrentan los motores de combustión interna, tales como emisiones contaminantes, agotamiento del petróleo o el auge de otros tipos de motores (vehículo eléctrico), vinculan el futuro de los vehículos propulsados por este tipo de motor a la mejora del mismo en cuanto a consumo de combustible y a emisiones contaminantes se refiere. Adicionalmente, la alta exigencia de la normativa actual y venidera está forzando a las empresas de automoción a centrarse en el desarrollo de estrategias innovadoras dirigidas a aumentar el rendimiento del motor con baja repercusión en emisiones contaminantes. Un primer paso para atajar esta problemática es centrarse en los procesos que ocurren en la cámara de combustión, que es la base del motor.
Teniendo en cuenta este escenario, el objetivo principal del presente trabajo es evaluar y optimizar el ciclo indicado de un motor de combustión interna por medio de una herramienta termodinámica 0D. El acoplamiento de esta herramienta, previamente desarrollada en el grupo de trabajo, con un modelo de emisiones de \NOx{} y una herramienta de optimización, permite la evaluación del impacto sobre el rendimiento indicado de varios límites operacionales y procesos reales que tienen lugar en la cámara de combustión.
En primer lugar, se ha evaluado el rendimiento indicado de diferentes ciclos ideales en los motores estudiados en el trabajo. Debido a que la diferencia entre ciclos ideales y reales es resultado de la existencia de varias imperfecciones, se ha realizado un estudio de sensibilidad de dichas imperfecciones para determinar cuáles son las que tienen mayor impacto sobre el rendimiento indicado. A continuación, se han buscado los ciclos teóricos óptimos, en este caso ya teniendo en cuenta los principales fenómenos que ocurren en el cilindro, para obtener la ley de combustión que maximiza el rendimiento indicado a la vez que cumple con diferentes restricciones mecánicas y límites de emisiones. En este análisis se concluye que la velocidad de combustión es el parámetro más importante a tener en cuenta.
Con el fin de evaluar algunas técnicas experimentales comúnmente usadas para aumentar la velocidad de combustión, parámetro clave como se ha comentado, se han utilizado diferentes enfoques tales como balances globales de energía, división de pérdidas y diseños de experimentos. Las conclusiones extraídas de dichos análisis han sido usadas para optimizar experimentalmente la ley de combustión. La comparación entre esta optimización experimental y la teórica proporciona el impacto en el rendimiento indicado que supone la limitación en la velocidad de combustión impuesta por el motor analizado. Esta metodología actúa como una herramienta de análisis comparativo entre diferentes arquitecturas del motor, estableciendo el techo de eficiencia bajo las condiciones de operación consideradas, y con ello la ganancia máxima alcanzable por un hipotético motor perfecto.[CAT] Les amenaces a què s'enfronten els motors de combustió interna, com ara emissions contaminants, esgotament del petroli o motors alternatius (vehicle elèctric), vinculen el futur dels vehicles propulsats per aquest tipus de motor a la millora del mateix quant a consum de combustible i a emissions contaminants es refereix. Addicionalment, l'alta exigència de la normativa actual i venidora està forçant a les empreses d'automoció a centrar-se en el desenrotllament d'estratègies innovadores dirigides a augmentar el rendiment del motor amb baixa repercussió en emissions contaminants. Un primer pas per a atallar esta problemàtica és centrar-se en els processos que ocorren en la cambra de combustió, que és la base del motor. Tenint en compte aquest escenari, l'objectiu principal del present treball és avaluar i optimitzar el cicle indicat d'un motor de combustió interna per mitjà d'una ferramenta termodinàmica 0D. L'adaptament d'esta ferramenta, prèviament desenrotllada en el grup de treball, amb un model d'emissions de \NOx{} i una ferramenta d'optimització, permet l'avaluació de l'impacte sobre el rendiment indicat d'uns quants límits operacionals i processos reals que tenen lloc en la cambra de combustió. En primer lloc, s'ha avaluat el rendiment indicat de diferents cicles ideals en els motors estudiats en el treball. Pel fet que la diferència entre cicles ideals i reals és resultat de l'existència de diverses imperfeccions, s'ha realitzat un estudi de sensibilitat de les dites imperfeccions per a determinar quines són les que tenen major impacte sobre el rendiment indicat. A continuació, s'han buscat els cicles teòrics òptims, en aquest cas ja tenint en compte els principals fenòmens que ocorren en el cilindre, per a obtindre la llei de combustió que maximitza el rendiment indicat al mateix temps que compleix amb diferents restriccions mecàniques i límits d'emissions. En aquest anàlisi es conclou que la velocitat de combustió és el paràmetre més important a tindre en compte. A fi d'avaluar algunes tècniques experimentals comunament usades per a augmentar la velocitat de combustió, paràmetre clau com s'ha comentat, s'han utilitzat diferents enfocaments com ara balanços globals d'energia, divisió de pèrdues i dissenys d'experiments. Les conclusions extretes d'aquest anàlisi han sigut usades per a optimitzar experimentalment la llei de combustió. La comparació entre esta optimització experimental i la teòrica proporciona l'impacte en el rendiment indicat que suposa la limitació en la velocitat de combustió imposada pel motor analitzat. Esta metodologia actua com una ferramenta d'anàlisi comparativa entre diferents arquitectures del motor, establint el sostre d'eficiència davall les condicions d'operació considerades, i amb això el guany màxim abastable per un hipotètic motor perfecte.
[EN] Issues affecting internal combustion engines, such as pollutant emissions, oil depletion and the raising of alternative powertrains (full electric vehicle), link the future of vehicles powered by this type of powertrain to its improvement in terms of fuel consumption and pollutant emissions. Additionally, the high stringency of the current and upcoming legislation is forcing automotive manufacturers to focus on developing innovative engine strategies aimed to increase the efficiency with low penalty in emissions. A first step to tackle this issue is to focus on the processes occurring in the combustion chamber, which is the core of the engine. Taking into account this scenario, the main objective of the present work is to assess and optimize the indicated cycle of an internal combustion engine based on a zero-dimensional thermodynamic tool. The coupling of this tool, previously developed in the work group, with a \NOx{} emissions model and an optimization tool allows evaluating the impact on gross indicated efficiency of several operational limits and real processes taking place in the combustion chamber. Thus, the first step was the assessment of the indicated efficiency of some ideal cycles in the engines studied in the work. Since the difference between ideal and real cycles is due to the existence of some imperfections, a sensitivity study of these imperfections is carried out to determine the ones with the highest impact on gross indicated efficiency. Later on, the optimum theoretical cycles have been searched for, now taking into account the main phenomena occurring in the cylinder, to get the combustion profile that maximizes the indicated efficiency while keeping some mechanical restrictions and emission limits. In this analysis, the combustion velocity raised as the most important parameter to take into account. In order to assess some experimental techniques commonly used to enhance the combustion velocity, key parameter as commented, different approaches such as Global Energy Balance, split of losses and the use of design of experiments have been conducted. The conclusions extracted from these analysis have been used to optimize experimentally the combustion law. The comparison between this experimental optimization and the theoretical one provides the impact on gross indicated efficiency of the combustion velocity limitation imposed by the engine hardware. This methodology acts as a benchmarking tool between different hardware architectures, setting the efficiency ceiling of the considered operating point, and thus the maximum gain achievable by implementing an hypothetical perfect hardware.
Blanco Cavero, D. (2018). Assessment and optimization of the indicated cycle with a 0D thermodynamic model [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/115934
TESIS
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Schäpers, Markus. "Exploring the Frustrated Spin-Chain Compound Linarite by NMR and Thermodynamic Investigations." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-153947.
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Within the last decades low-dimensional frustrated quantum spin systems have attracted great interest in the field of modern research. In these systems a competition of various magnetic interactions takes place, leading to an energetically degenerated magnetic ground state, and thus to the occurrence of exotic, unconventional physical properties at low temperatures.
This thesis focuses on the quasi one-dimensional frustrated spin chain system linarite, PbCuSO4(OH)2. In this compound the basic building blocks are CuO4 plaquettes which are connected to each other along one crystallographic direction, analogue to a chain. The frustration in linarite is established due to the competition between the magnetic interactions. The nearest-neighbor magnetic spins are coupled ferromagnetically along the chain via a coupling constant J1, while the next-nearest neighbors are coupled antiferromagnetically via a coupling constant J2. For this configuration it is not possible to satisfy all magnetic couplings simultaneously, hence the system is magnetically frustrated.
In this work, comprehensive thermodynamic and nuclear magnetic resonance (NMR) studies demonstrate that linarite is one of the richest and most fascinating compounds in the class of low-dimensional frustrated magnets. By means of susceptibility, magnetization, specific heat, magnetocaloric effect, magnetostriction, and thermal-expansion measurements a rich magnetic phase diagram could be mapped out below a temperature of 2.8 K. The phase diagram contains five different magnetic regions/phases for an external magnetic field pointing along the chain direction. Based on the thermodynamic studies it was possible to calculate the exchange integrals within the frustrated J1-J2 model and extensions of it by using various theoretical approaches.
The magnetic microscopic nature of the different long-range magnetic phases present in linarite were investigated by NMR measurements and by collaborative neutron scattering experiments. The ground state (phase I) is identified as an incommensurate elliptical helical structure. Via a theoretical modelling the 1H-NMR spectrum of the ground state could be explained, revealing a rearrangement of the zero-field structure in an external magnetic field of 2.0 T used for the NMR studies. By further increasing the external field the system undergoes a complex spin flop transition in two steps (phase I - phase III - phase IV). In phase III a phase separation takes place where one part of the spins form a circular spiral structure while the remaining fraction form a simple antiferromagnetic structure. In phase IV the remaining circular spiral structure vanishes, so that all spins collectively form the antiferromagnetic collinear phase. The most peculiar physical properties studied in this thesis take place in region V at high fields, showing only tiny features in the thermodynamic properties. The magnetic spins in region V form a sine-wave modulated spin-density structure as identified via NMR and neutron investigations. It is discussed whether region V is related to a multipolar phase or if the spin-density wave structure could possibly coexist with such a phase.
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Fisher, Paul D. "Computer model of the performance of a thermoacoustic generator." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA237680.
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Thesis (M.S. in Physics)--Naval Postgraduate School, June 1990.Thesis Advisor(s): Atchley, A.A. Second Reader: Hofler, T.J. "June 1990." Description based on signature page. DTIC Identifiers: Thermoacoustics, sound generators. Author(s) subject terms: Thermoacoustics. Includes bibliographical references (p. 51). Also available in print.
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Lu, Xia. "Nonequilibrium thermodynamic models for the dynamic behavior of polycrystalline solids." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/12549.
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Plano, Marco. "Evaluation of thermodynamic models used for wet gas compressor design." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-26062.
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Big investments are done in developing wet gas compression technology. The reasons behind these investments are the need to improve the recovery from old reservoirs and the need to make small reservoirs economically profitable.This work will use a model with the software NeqSim in order to simulate a wet gas compressor and evaluate the sensitivity of performance evaluation to the Equation of State used. It will be easier to evaluate how much the data provided by vendors will effectively represent the real compressor's performance in the needed operating conditions. Then it is needed to know how much the work required from the compressor is influenced by the Equation of State used for the evaluation.When it comes to the compressor work estimation, a maximum of 3% of deviation has been identified. According to the API 617 [32], this deviation is considered acceptable.The deviation in estimating the compressor outlet temperature is maximum 2 K and it depends on the composition of the fluid and the pressure of operation. For the polytropic efficiency instead, the highest deviation is 2%. Again, according to the standard API 617, a deviation up to 2% is considered acceptable.Furthermore, this work will highlight the parameters that require higher accuracy when dealing with wet gas compressor performance evaluation. Thus, any equation of state able to give reasonable accuracy in these parameters will be expected to give accurate results in compressor's performance evaluation.Finally, in conjunction with the preliminary work of this thesis [3], it has been possible to identify the Cubic Plus Association (CPA) equation of state as more suitable for wet gas calculations than Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK) Equations of State.
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Ambler, Michael. "Thermodynamics of ice interfaces and structures within a coarse-grained model of water." Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/90109/.
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This research applies the capillary wave method (CWM) to quasi-2D systems in order to calculate the solid-liquid coexistence interfacial free energy (γ) of ice-Ic, ice-Ih and ice-0, with water, at 1 atm, within molecular dynamics simulations employing the coarse-grained monatomic water (mW) model. Investigations are performed to determine how the measured interfacial stiffness (~γ) is affected using various: i) order parameters, to distinguish between the solid and the liquid; ii) analysis discretisation, for interface profiling; iii) system thicknesses. The rationality that ice-I nucleation can be catalysed at strong supercooling within a shell of ice-0 is explored. It is found that at 215.2 K such nucleation could occur, forming an ice-0 shell of 3:3 Å thick around a core of ice-Ih. Free energy perturbation is also applied to the mW model using Monte Carlo simulations, in an attempt to increase the Gibbs free energy gap between ice-Ic and ice-Ih to more closely match values previously reported from experiments and ab initio calculations. However, the Gibbs free energy gap is only increased to 5.6 J mol⁻¹, at 240 K, before the ice-Ic and ice-Ih melting temperatures fall to below 240 K; failing to reach the expected value. This suggests that the mW model, despite its successes, does not capture the true mechanism behind the formation ice-Ic and ice-Ih stacking faults at all degrees of supercooling; the formation of which is rather an artefact of the model itself.
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Waters, Laura Jane. "Thermodynamic analysis of the partitioning of dialkyl phthalate esters with model cell membranes." Thesis, University of Greenwich, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.483499.
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SIQUEIRA, ROGERIO NAVARRO CORREIA DE. "THERMODYNAMIC MODELING OF TIO2 CONTAINING SLAGS: KAPOOR-FROHBERG-GAYE MODIFIED QUASI-CHEMICAL MODEL." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2005. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=8045@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORO presente trabalho teve como objetivo central, a modelagem termodinâmica computacional de escórias contendo TiO2 através do modelo termodinâmico quase-químico estatístico de Kapoor-Frohberg- Gaye. Neste contexto, os seguintes pseudo-binários foram investigados: Al2O3-TiO2, MgOTiO2, MnO-TiO2 e FeO-TiO2. Os resultados das otimizações demonstraram a possibilidade de emprego do referido modelo para uma descrição quantitativa do comportamento termodinâmico destes sistemas. Tanto os diagramas de fases quanto os dados de atividade química foram avaliados e satisfatoriamente descritos pelo modelo. Adicionalmente, ficou evidente a necessidade de correção dos modelos de energia de Gibbs (G) dos óxidos mistos presentes em cada um dos sistemas. As correções determinaram, para a faixa de temperatura onde os dados termodinâmicos foram otimizados, desvios relativos em G inferiores a 1%, sendo perfeitamente aceitáveis, levando-se em consideração comparações entre valores de energia de Gibbs disponíveis na literatura. Os resultados do presente trabalho foram comparados com os obtidos por Erickson e Pelton (1992). Nesta última referência os autores empregaram o modelo de Pelton e Blander (1986), em essência muito similar ao modelo utilizado no presente trabalho. As comparações evidenciaram que os dois modelos podem fornecer uma descrição quantitativa equivalente para o comportamento termodinâmico experimental.
The present work has the main goal of modeling liquid oxide mixtures (slags) by using the Kapoor-Frohberg-Gaye modified quasi- chemical model. In this context the thermodynamic behavior of the following systems was studied: Al2O3-TiO2, MnO-TiO2, MgO-TiO2 and FeO-TiO2. The optimization results confirmed that the Kapoor-Frohberg-Gaye model can in fact be used for the quantitative description of the thermodynamics of all the investigated systems. Phase diagrams and chemical activity data were assessed and satisfactorily described by the model. It was evident that the Gibbs energy (G) of the mixed oxides had to be modified. However, the relative energy corrections for the Gibbs energy was equal or less then 1%, for the temperature range between where the thermodynamic data was optimized, which is quite acceptable, taking into account comparisons of Gibbs energy values from the current literature. Comparisons were done with the results from Erickson e Pelton (1992), which used a modified quasi-chemical model proposed by Pelton e Blander (1986), very similar to the model used in the present work. The comparison shows that the two models can offer an equivalent quantitative description of the experimental thermodynamics.
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Foster, Andrew William. "Characterisation of a cyanobacterial nickel sensor and a thermodynamic model of metal sensing." Thesis, University of Newcastle upon Tyne, 2013. http://hdl.handle.net/10443/2395.
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The product of Synechocystis PCC 6803 open reading frame slr0176, InrS (Internal nickel responsive Sensor) a member of the CsoR-RcnR metalloregulatory family, has been characterised in the course of this work and found to regulate the expression of nrsD, encoding a nickel export protein, in a nickel dependent manner. InrS occludes a previously unidentified cryptic promoter in a nickel resistance operon. In addition to Ni(II) InrS is also competent to bind and respond to Zn(II), Co(II) Cu(II) and Cu(I) in vitro as determined by metal binding studies & fluorescence anisotropy. The factors that favour a response to nickel but disfavour responses to zinc and copper in vivo have been explored including determining allosteric coupling free energies of Ni(II) and Cu(I) binding. The cognate and non-cognate metal binding affinities of InrS, ZiaR (zinc-sensing SmtB family member), Zur (zinc-sensing Fur family member) and CoaR (cobalt-sensing MerR family) have been determined through competition with a range of metal chelators and infer that selective sensing of zinc and nickel can be dictated by the relative affinities of the metalloregulators but selective cobalt sensing cannot. The primary metal coordination sphere of InrS has been investigated through a combination of site directed mutagenesis and metal binding studies. Three of four Ni(II) ligands constituting the square planar Ni(II) site have been identified and mutant variants with weakened Ni(II) affinities produced. InrS displays metal binding properties characteristic of the copper sensing sub-branch of this protein family thought to be a consequence of the primary coordination sphere. Results of this work have been used to refine predictions as to the metal(s) sensed by uncharacterised members of this protein family based on the predicted secondary rather than primary coordination sphere. An alternative allosteric network involving a secondary coordination sphere hydrogen bond in nickel sensing CsoR-RcnRs is proposed.