Predictions of titanium alloy properties using thermodynamic modeling tools
Zhang, F.; Xie, F.-Y.; Chen, S.-L.; Chang, Y. A.; Furrer, D.; Venkatesh, V.
2005-12-01
Thermodynamic modeling tools have become essential in understanding the effect of alloy chemistry on the final microstructure of a material. Implementation of such tools to improve titanium processing via parameter optimization has resulted in significant cost savings through the elimination of shop/laboratory trials and tests. In this study, a thermodynamic modeling tool developed at CompuTherm, LLC, is being used to predict β transus, phase proportions, phase chemistries, partitioning coefficients, and phase boundaries of multicomponent titanium alloys. This modeling tool includes Pandat, software for multicomponent phase equilibrium calculations, and PanTitanium, a thermodynamic database for titanium alloys. Model predictions are compared with experimental results for one α-β alloy (Ti-64) and two near-β alloys (Ti-17 and Ti-10-2-3). The alloying elements, especially the interstitial elements O, N, H, and C, have been shown to have a significant effect on the β transus temperature, and are discussed in more detail herein.
Energy Technology Data Exchange (ETDEWEB)
Hagemann, Sven; Schoenwiese, Dagmar; Scharge, Tina
2015-07-15
The report on tools and data for the geochemical modeling covers the following issues: experimental methods and theoretical models, design of a thermodynamic model for reduced sulfur species, thermodynamic models for background salts, tools for the uncertainty and sensitivity analyses of geochemical equilibrium modeling.
Araujo, Pablo Granda; Gras, Anna; Ginovart, Marta
2016-01-01
Modelling cellular metabolism is a strategic factor in investigating microbial behaviour and interactions, especially for bio-technological processes. A key factor for modelling microbial activity is the calculation of nutrient amounts and products generated as a result of the microbial metabolism. Representing metabolic pathways through balanced reactions is a complex and time-consuming task for biologists, ecologists, modellers and engineers. A new computational tool to represent microbial pathways through microbial metabolic reactions (MMRs) using the approach of the Thermodynamic Electron Equivalents Model has been designed and implemented in the open-access framework NetLogo. This computational tool, called MbT-Tool (Metabolism based on Thermodynamics) can write MMRs for different microbial functional groups, such as aerobic heterotrophs, nitrifiers, denitrifiers, methanogens, sulphate reducers, sulphide oxidizers and fermenters. The MbT-Tool's code contains eighteen organic and twenty inorganic reduction-half-reactions, four N-sources (NH4 (+), NO3 (-), NO2 (-), N2) to biomass synthesis and twenty-four microbial empirical formulas, one of which can be determined by the user (CnHaObNc). MbT-Tool is an open-source program capable of writing MMRs based on thermodynamic concepts, which are applicable in a wide range of academic research interested in designing, optimizing and modelling microbial activity without any extensive chemical, microbiological and programing experience.
Directory of Open Access Journals (Sweden)
Pablo Araujo Granda
2016-01-01
Full Text Available Modelling cellular metabolism is a strategic factor in investigating microbial behaviour and interactions, especially for bio-technological processes. A key factor for modelling microbial activity is the calculation of nutrient amounts and products generated as a result of the microbial metabolism. Representing metabolic pathways through balanced reactions is a complex and time-consuming task for biologists, ecologists, modellers and engineers. A new computational tool to represent microbial pathways through microbial metabolic reactions (MMRs using the approach of the Thermodynamic Electron Equivalents Model has been designed and implemented in the open-access framework NetLogo. This computational tool, called MbT-Tool (Metabolism based on Thermodynamics can write MMRs for different microbial functional groups, such as aerobic heterotrophs, nitrifiers, denitrifiers, methanogens, sulphate reducers, sulphide oxidizers and fermenters. The MbT-Tool's code contains eighteen organic and twenty inorganic reduction-half-reactions, four N-sources (NH4+, NO3−, NO2−, N2 to biomass synthesis and twenty-four microbial empirical formulas, one of which can be determined by the user (CnHaObNc. MbT-Tool is an open-source program capable of writing MMRs based on thermodynamic concepts, which are applicable in a wide range of academic research interested in designing, optimizing and modelling microbial activity without any extensive chemical, microbiological and programing experience.
Hudson, R.; Omanovic, D.; Kogut, M.; Voelker, B. M.
2016-02-01
Complexometric titration of natural ligands in seawater using the competitive ligand equilibration-adsorptive cathodic stripping voltammetry method (CLE-AdCSV) is the method of choice for characterizing the organic complexation of Cu and Fe in seawater. Interpreting such titration data is made difficult by the complexity of the modeling process, which arises from the need to estimate non-linear model equations, the potential for artifacts, and the use of reference equilibrium constants that have been subject of only limited study. Due to the need to model multi-component equilibrium systems when these titration data, a variety of approximations have been made in order to allow standard linear and non-linear regression tools to be applied. Two software tools, KINETEQL and ProMCC, solve the model equations exactly and allow users to estimate complexation model parameters accurately. ProMCC excels in visualization and ease-of-use, while KINETEQL provides the user with flexibility in the definition of equilibrium models and has the additional capability of solving reaction kinetics problems. A detailed example of the application of KINETQL to simulating the kinetics of Cu(II) complexation by EDTA in seawater will be illustrated. The implications of kinetics for experimental determination of the stability constants of natural Cu- and Fe-binding ligands will be addressed. These modeling tools make it feasible to design experiments and analyze datasets using new, complex approaches to data analysis, i.e., data from multiple CLE-AdCSV titrations obtained in different analytical windows. This approach can help solve to the problem of internal calibration in waters that contain mixtures of weak and strong ligands. Because it attempts to model data that span a much wider range in chemistries, the "multiwindow" approach is especially vulnerable to bias in the reference complex stability constants. The difficulty of obtaining coherent models of multiwindow CLE-AdCSV datasets
Energy Technology Data Exchange (ETDEWEB)
PIERSON KL; MEINERT FL
2012-01-26
Two notable modeling efforts within the Hanford Tank Waste Operations Simulator (HTWOS) are currently underway to (1) increase the robustness of the underlying chemistry approximations through the development and implementation of an aqueous thermodynamic model, and (2) add enhanced planning capabilities to the HTWOS model through development and incorporation of the lifecycle cost model (LCM). Since even seemingly small changes in apparent waste composition or treatment parameters can result in large changes in quantities of high-level waste (HLW) and low-activity waste (LAW) glass, mission duration or lifecycle cost, a solubility model that more accurately depicts the phases and concentrations of constituents in tank waste is required. The LCM enables evaluation of the interactions of proposed changes on lifecycle mission costs, which is critical for decision makers.
Microscopic Models for Chemical Thermodynamics
Malyshev, Vadim A.
2011-01-01
We introduce an infinite particle system dynamics, which includes stochastic chemical kinetics models, the classical Kac model and free space movement. We study energy redistribution between two energy types (kinetic and chemical) in different time scales, similar to energy redistribution in the living organisms. One example is considered in great detail, where the model provides main formulas of chemical thermodynamics.
Microscopic Models for Chemical Thermodynamics
Malyshev, V A
2011-01-01
We introduce an infinite particle system dynamics, which includes stochastic chemical kinetics models, the classical Kac model and free space movement. We study energy redistribution between two energy types (kinetic and chemical) in different time scales, similar to energy redistribution in the living cell. One example is considered in great detail, where the model provides main formulas of chemical thermodynamics.
Microscopic Models for Chemical Thermodynamics
Malyshev, V. A.
2005-06-01
We introduce an infinite particle system dynamics, which includes stochastic chemical kinetics models, the classical Kac model and free space movement. We study energy redistribution between two energy types (kinetic and chemical) in different time scales, similar to energy redistribution in the living cell. One example is considered in great detail, where the model provides main formulas of chemical thermodynamics.
Thermodynamic Model of Spatial Memory
Kaufman, Miron; Allen, P.
1998-03-01
We develop and test a thermodynamic model of spatial memory. Our model is an application of statistical thermodynamics to cognitive science. It is related to applications of the statistical mechanics framework in parallel distributed processes research. Our macroscopic model allows us to evaluate an entropy associated with spatial memory tasks. We find that older adults exhibit higher levels of entropy than younger adults. Thurstone's Law of Categorical Judgment, according to which the discriminal processes along the psychological continuum produced by presentations of a single stimulus are normally distributed, is explained by using a Hooke spring model of spatial memory. We have also analyzed a nonlinear modification of the ideal spring model of spatial memory. This work is supported by NIH/NIA grant AG09282-06.
Thermodynamics of the PNJL model
Energy Technology Data Exchange (ETDEWEB)
Ratti, C. [ECT, Villazzano (Trento) (Italy); INFN, Gruppo Collegato di Trento, Povo (Trento) (Italy); Roessner, S.; Thaler, M.A.; Weise, W. [Technische Universitaet Muenchen, Physik-Department, Garching (Germany)
2007-01-15
QCD thermodynamics is investigated by means of the Polyakov-loop-extended Nambu-Jona-Lasinio (PNJL) model, in which quarks couple simultaneously to the chiral condensate and to a background temporal gauge field representing Polyakov loop dynamics. The behaviour of the Polyakov loop as a function of temperature is obtained by minimising the thermodynamic potential of the system. A Taylor series expansion of the pressure is performed. Pressure difference and quark number density are then evaluated up to sixth order in the quark chemical potential and compared to the corresponding lattice data. The validity of the Taylor expansion is discussed within our model through a comparison between the full results and the truncated ones. (orig.)
Thermodynamic modeling of complex systems
DEFF Research Database (Denmark)
Liang, Xiaodong
Offshore reservoirs represent one of the major growth areas of the oil and gas industry, and environmental safety is one of the biggest challenges for the offshore exploration and production. The oil accidents in the Gulf of Mexico in 1979 and 2010 were two of the biggest disasters in history...... after an oil spill. Engineering thermodynamics could be applied in the state-of-the-art sonar products through advanced artificial technology, if the speed of sound, solubility and density of oil-seawater systems could be satisfactorily modelled. The addition of methanol or glycols into unprocessed well...
Modeling the thermodynamics of QCD
Energy Technology Data Exchange (ETDEWEB)
Hell, Thomas
2010-07-26
Strongly interacting (QCD) matter is expected to exhibit a multifaceted phase structure: a hadron gas at low temperatures, a quark-gluon plasma at very high temperatures, nuclear matter in the low-temperature and high-density region, color superconductors at asymptotically high densities. Most of the conjectured phases cannot yet be scrutinized by experiments. Much of the present picture - particularly concerning the intermediate temperature and density area of the phase diagram of QCD matter - is based on model calculations. Further insights come from Lattice-QCD computations. The present thesis elaborates a nonlocal covariant extension of the Nambu and Jona-Lasinio (NJL) model with built-in constraints from the running coupling of QCD at high-momentum and instanton physics at low-momentum scales. We present this model for two and three quark flavors (in the latter case paying particular attention to the axial anomaly). At finite temperatures and densities, gluon dynamics is incorporated through a gluonic background field, expressed in terms of the Polyakov loop (P). The thermodynamics of this nonlocal PNJL model accounts for both chiral and deconfinement transitions. We obtain results in mean-field approximation and beyond, including additional pionic and kaonic contributions to the chiral condensate, the pressure and other thermodynamic quantities. Finally, the nonlocal PNJL model is applied to the finite-density region of the QCD phase diagram; for three quark flavors we investigate, in particular, the dependence of the critical point appearing in the models on the axial anomaly. The thesis closes with a derivation of the nonlocal PNJL model from first principles of QCD. (orig.)
Thermodynamic Model of Transcription Elongation
Tadigotla, Vasisht; O'Maoileidigh, Daibhid; Sengupta, Anirvan; Epshtein, Vitaly; Ebright, Richard; Nudler, Evgeny; Ruckenstein, Andrei
2006-03-01
We present a statistical mechanics approach to the prediction of backtracked pauses in prokaryotic transcription elongation derived from structural models of the transcription elongation complex (TEC). Our algorithm is based on the thermodynamic stability of TEC along the DNA template calculated from the sequence dependent free-energy of DNA-DNA, DNA-RNA and RNA-RNA base pairing associated with (a) the translocation and size fluctuations of the transcription bubble; (b) the changes in the DNA-RNA hybrid; and (c) the changes in the RNA folding free-energy. The calculations involve no adjustable parameters apart from a cutoff used to discriminate paused from non-paused complexes. When applied to 100 experimental pauses in transcription elongation by E. coli RNA polymerase on ten DNA templates the approach produces highly statistically significant results. Transcription elongation is an inherently kinetic process and a simplified kinetic model with the same predictive power is presented separately.
Thermodynamically consistent model calibration in chemical kinetics
Directory of Open Access Journals (Sweden)
Goutsias John
2011-05-01
Full Text Available Abstract Background The dynamics of biochemical reaction systems are constrained by the fundamental laws of thermodynamics, which impose well-defined relationships among the reaction rate constants characterizing these systems. Constructing biochemical reaction systems from experimental observations often leads to parameter values that do not satisfy the necessary thermodynamic constraints. This can result in models that are not physically realizable and may lead to inaccurate, or even erroneous, descriptions of cellular function. Results We introduce a thermodynamically consistent model calibration (TCMC method that can be effectively used to provide thermodynamically feasible values for the parameters of an open biochemical reaction system. The proposed method formulates the model calibration problem as a constrained optimization problem that takes thermodynamic constraints (and, if desired, additional non-thermodynamic constraints into account. By calculating thermodynamically feasible values for the kinetic parameters of a well-known model of the EGF/ERK signaling cascade, we demonstrate the qualitative and quantitative significance of imposing thermodynamic constraints on these parameters and the effectiveness of our method for accomplishing this important task. MATLAB software, using the Systems Biology Toolbox 2.1, can be accessed from http://www.cis.jhu.edu/~goutsias/CSS lab/software.html. An SBML file containing the thermodynamically feasible EGF/ERK signaling cascade model can be found in the BioModels database. Conclusions TCMC is a simple and flexible method for obtaining physically plausible values for the kinetic parameters of open biochemical reaction systems. It can be effectively used to recalculate a thermodynamically consistent set of parameter values for existing thermodynamically infeasible biochemical reaction models of cellular function as well as to estimate thermodynamically feasible values for the parameters of new
Directory of Open Access Journals (Sweden)
Juan Carlos Armas
2011-05-01
Full Text Available An analysis of a chilled water central air conditioning system is presented. The object was to calculate main cycle component irreversibility, as well as evaluating this indicator’s sensitivity to operational variations. Artificial neural networks (ANN, genetic algorithms (GA and Matlab tools were used to calculate refrigerant thermodynamic properties during each cycle stage. These tools interacted with equations describing the system’s thermodynamic behaviour. Refrigerant temperature, when released from the compressor, was determined by a hybrid model combining the neural model with a simple genetic algorithm used as optimisation tool; the cycle’s components which were most sensitive to changes in working conditions were identified. It was concluded that the compressor, evaporator and expansion mechanism (in that order represented significant exergy losses reaching 85.62% of total system irreversibility. A very useful tool was thus developed for evaluating these systems.
Thermodynamic Model of Noise Information Transfer
Hejna, Bohdan
2008-10-01
In this paper we apply a certain unifying physical description of the results of Information Theory. Assuming that heat entropy is a thermodynamic realization of information entropy [2], we construct a cyclical, thermodynamic, average-value model of an information transfer chain [3] as a general heat engine, in particular a Carnot engine, reversible or irreversible. A working medium of the cycle (a thermodynamic system transforming input heat energy) can be considered as a thermodynamic, average-value model or, as such, as a realization of an information transfer channel. We show that in a model realized in this way the extended II. Principle of Thermodynamics is valid [2] and we formulate its information form.
Ogunwuyi, Oluwatosin
Technology is becoming a more critical agent for supporting learning as well as research in science and engineering. In particular, technology-based tools in the form of simulations and virtual environments support learning using mathematical models and computational methods. The purpose of this research is to: (a) measure the value added in conveying Thermodynamics of materials concepts with a blended learning environment using computational simulation tools with lectures; and (b) characterize students' use of representational forms to convey their conceptual understanding of core concepts within a learning environment that blended Gibbs computational resource and traditional lectures. A mix-method approach was implemented that included the use of statistical analysis to compare student test performance as a result of interacting with Gibbs tool and the use of Grounded Theory inductive analysis to explore students' use of representational forms to express their understanding of thermodynamics of material concepts. Results for the quantitative study revealed positive gains in students' conceptual understanding before and after interacting with Gibbs tool for the majority of the concepts tested. In addition, insight gained from the qualitative analysis helped provide understanding about how students utilized representational forms in communicating their understanding of thermodynamics of material concepts. Knowledge of how novice students construct meaning in this context will provide insight for engineering education instructors and researchers in understanding students' learning processes in the context of educational environments that integrate expert simulation tools as part of their instructional resources for foundational domain knowledge.
A thermodynamic model of sliding friction
Directory of Open Access Journals (Sweden)
Lasse Makkonen
2012-03-01
Full Text Available A first principles thermodynamic model of sliding friction is derived. The model predictions are in agreement with the observed friction laws both in macro- and nanoscale. When applied to calculating the friction coefficient the model provides a quantitative agreement with recent atomic force microscopy measurements on a number of materials.
Thermodynamic state ensemble models of cis-regulation.
Directory of Open Access Journals (Sweden)
Marc S Sherman
Full Text Available A major goal in computational biology is to develop models that accurately predict a gene's expression from its surrounding regulatory DNA. Here we present one class of such models, thermodynamic state ensemble models. We describe the biochemical derivation of the thermodynamic framework in simple terms, and lay out the mathematical components that comprise each model. These components include (1 the possible states of a promoter, where a state is defined as a particular arrangement of transcription factors bound to a DNA promoter, (2 the binding constants that describe the affinity of the protein-protein and protein-DNA interactions that occur in each state, and (3 whether each state is capable of transcribing. Using these components, we demonstrate how to compute a cis-regulatory function that encodes the probability of a promoter being active. Our intention is to provide enough detail so that readers with little background in thermodynamics can compose their own cis-regulatory functions. To facilitate this goal, we also describe a matrix form of the model that can be easily coded in any programming language. This formalism has great flexibility, which we show by illustrating how phenomena such as competition between transcription factors and cooperativity are readily incorporated into these models. Using this framework, we also demonstrate that Michaelis-like functions, another class of cis-regulatory models, are a subset of the thermodynamic framework with specific assumptions. By recasting Michaelis-like functions as thermodynamic functions, we emphasize the relationship between these models and delineate the specific circumstances representable by each approach. Application of thermodynamic state ensemble models is likely to be an important tool in unraveling the physical basis of combinatorial cis-regulation and in generating formalisms that accurately predict gene expression from DNA sequence.
Thermodynamic Model of Afterburning in Explosions
Energy Technology Data Exchange (ETDEWEB)
Kuhl, A L; Howard, M; Fried, L
2003-04-23
Thermodynamic states encountered during afterburning of explosion products gases in air were analyzed with the Cheetah code. Results are displayed in the form of Le Chatelier diagrams: the locus of states of specific internal energy versus temperature, for six different condensed explosives charges. Accuracy of the results was confirmed by comparing the fuel and products curves with the heats of detonation and combustion, and species composition as measured in bomb calorimeter experiments. Results were fit with analytic functions u = f ( T ) suitable for specifying the thermodynamic properties required for gas-dynamic models of afterburning in explosions.
Systematic assignment of thermodynamic constraints in metabolic network models
Directory of Open Access Journals (Sweden)
Heinemann Matthias
2006-11-01
Full Text Available Abstract Background The availability of genome sequences for many organisms enabled the reconstruction of several genome-scale metabolic network models. Currently, significant efforts are put into the automated reconstruction of such models. For this, several computational tools have been developed that particularly assist in identifying and compiling the organism-specific lists of metabolic reactions. In contrast, the last step of the model reconstruction process, which is the definition of the thermodynamic constraints in terms of reaction directionalities, still needs to be done manually. No computational method exists that allows for an automated and systematic assignment of reaction directions in genome-scale models. Results We present an algorithm that – based on thermodynamics, network topology and heuristic rules – automatically assigns reaction directions in metabolic models such that the reaction network is thermodynamically feasible with respect to the production of energy equivalents. It first exploits all available experimentally derived Gibbs energies of formation to identify irreversible reactions. As these thermodynamic data are not available for all metabolites, in a next step, further reaction directions are assigned on the basis of network topology considerations and thermodynamics-based heuristic rules. Briefly, the algorithm identifies reaction subsets from the metabolic network that are able to convert low-energy co-substrates into their high-energy counterparts and thus net produce energy. Our algorithm aims at disabling such thermodynamically infeasible cyclic operation of reaction subnetworks by assigning reaction directions based on a set of thermodynamics-derived heuristic rules. We demonstrate our algorithm on a genome-scale metabolic model of E. coli. The introduced systematic direction assignment yielded 130 irreversible reactions (out of 920 total reactions, which corresponds to about 70% of all irreversible
NONEQUILIBRIUM THERMODYNAMICS: A POWER FUL TOOL FOR SCIENTISTS AND ENGINEERS
Directory of Open Access Journals (Sweden)
HANS CHRISTIAN ÖTTINGER
2012-01-01
Full Text Available We present the two-generator framework of nonequilibrium thermodynamics with a strong emphasis on fundamental notions rather than mathematical details. The underlying sta- tistical mechanics and the implications for thermodynamically guided simulation techniques are sketched briefly. The usefulness and maturity of the framework are illustrated by reviewing a large number of recent far-from-equilibrium applications, where nonlinearity rules. Finally, we oter some promising perspectives for the future of nonequilibrium thermodynamics.
Improving a Mars photochemical model with thermodynamics
Delgado-Bonal, A.; Martin-Torres, F. J.; Simoncini, E.
2012-12-01
Different conditions of temperature and pressure drive the chemistry of a planetary atmosphere to different steady states. However, the different thermodynamic conditions are not considered in many studies about the abundance of liquid water, methane or other important compounds called sometimes biomarkers, leading to wrong calculations. We have adapted a photochemical model for Mars atmosphere [1] to the proper thermodynamical conditions and coupled it with realistic profiles of Temperature and Pressure previously calculated with PRAMS GCM. As we have shown previously [2], the influence of T,P and molar fraction in the Gibbs Free Energy calculations and therefore in the kinetics of the gases in a planetary atmosphere has a huge influence in the final steady state and concentrations. The study is applied to different compounds and determine their abundance with real Mars conditions. The existence and reactivity of liquid water on Mars is highly linked with the presence of other compounds in the atmosphere such as Ozone, OH or CH4, and the determination of those also require the thermodynamical studies. [1 ] Franck Lefèvre and François Forget. Observed variations of methane on Mars unexplained by known atmospheric chemistry and physics. Nature 460, 720-723 (6 August 2009) [2] Simoncini E., Delgado-Bonal A., Martin-Torres F.J., Accounting thermodynamic conditions in chemical models of planetary atmospheres. Submitted to Astrophysical Journal.
Population Density Modeling Tool
2014-02-05
194 POPULATION DENSITY MODELING TOOL by Davy Andrew Michael Knott David Burke 26 June 2012 Distribution...MARYLAND NAWCADPAX/TR-2012/194 26 June 2012 POPULATION DENSITY MODELING TOOL by Davy Andrew Michael Knott David Burke...Density Modeling Tool 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Davy Andrew Michael Knott David Burke 5d. PROJECT NUMBER
Expanding Universe: Thermodynamical Aspects From Different Models
Pal, Sridip
2012-01-01
The pivotal point of the paper is to discuss the behavior of temperature, pressure, energy density as a function of volume along with determination of caloric EoS from following two model: $w(z)=w_{0}+w_{1}\\ln(1+z)$ & $ w(z)=-1+\\frac{(1+z)}{3}\\frac{A_{1}+2A_{2}(1+z)}{A_{0}+2A_{1}(1+z)+A_{2}(1+z)^{2}}$. The time scale of instability for this two models is discussed. In the paper we then generalize our result and arrive at general expression for energy density irrespective of the model. The thermodynamical stability for both of the model and the general case is discussed from this viewpoint. We also arrive at a condition on the limiting behavior of thermodynamic parameter to validate the third law of thermodynamics and interpret the general mathematical expression of integration constant $U_{0}$ (what we get while integrating energy conservation equation) physically relating it to number of micro states. The constraint on the allowed values of the parameters of the models is discussed which ascertains stabi...
Modeling thermodynamics of Fe-N phases
DEFF Research Database (Denmark)
Pekelharing, Marjon I.; Böttger, Amarante; Somers, Marcel A. J.
1999-01-01
In the present work homogeneous epsilon-nitride powders prepared at 723 K, having nitrogen contents ranging from 26.1 at. % N (z=0.29) to 31.1 at.% N (z=0.10), were investigated with X-ray diffraction (XRD) and Mössbauer spectroscopy. A thermodynamic model accounting for the two possible configur......In the present work homogeneous epsilon-nitride powders prepared at 723 K, having nitrogen contents ranging from 26.1 at. % N (z=0.29) to 31.1 at.% N (z=0.10), were investigated with X-ray diffraction (XRD) and Mössbauer spectroscopy. A thermodynamic model accounting for the two possible...
Molecular Thermodynamic Model for Associated Polymers
Institute of Scientific and Technical Information of China (English)
PENG,Chang-Jun(彭昌军); LIU,Hong-Lai(刘洪来); HU,Ying(胡英)
2001-01-01
A molecular thermedynmnic model for homopolyrner and copolymer systems with association segments was establishedby adopting the molecular thermodynamic model for hard-sphere-chain fluid as a reference,a perturbation term contributed by the square-well potential and a contribution of as sociation terms.The latter considers the multi-associated-seg-ments in a chain-like molecule based on the shield-sticky model of chemical association.The model can be used to correlate the pVT of melten homopolymer and copolymer.Good agree-ments with experimental data have been obtained.
Thermodynamic and kinetic modelling: creep resistant materials
DEFF Research Database (Denmark)
Hald, John; Korcakova, L.; Danielsen, Hilmar Kjartansson
2008-01-01
particles and coarsening of MX, M23C6 and Laves phase particles. The modelling provided new insight into the long term stability of new steels. Modelling of the detrimental precipitation of Z phase Cr(V,Nb)N is described, which points to new approaches in alloy development for higher temperatures......The use of thermodynamic and kinetic modelling of microstructure evolution in materials exposed to high temperatures in power plants is demonstrated with two examples. Precipitate stability in martensitic 9–12%Cr steels is modelled including equilibrium phase stability, growth of Laves phase...
Thermodynamic and kinetic modeling of transcriptional pausing
Tadigotla, Vasisht R.; Maoiléidigh, Dáibhid Ó; Sengupta, Anirvan M.; Epshtein, Vitaly; Ebright, Richard H.; Nudler, Evgeny; Ruckenstein, Andrei E.
2006-01-01
We present a statistical mechanics approach for the prediction of backtracked pauses in bacterial transcription elongation derived from structural models of the transcription elongation complex (EC). Our algorithm is based on the thermodynamic stability of the EC along the DNA template calculated from the sequence-dependent free energy of DNA–DNA, DNA–RNA, and RNA–RNA base pairing associated with (i) the translocational and size fluctuations of the transcription bubble; (ii) changes in the as...
Standard Model thermodynamics across the electroweak crossover
Energy Technology Data Exchange (ETDEWEB)
Laine, M.; Meyer, M. [Institute for Theoretical Physics, Albert Einstein Center, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland)
2015-07-22
Even though the Standard Model with a Higgs mass m{sub \\tiny H}=125 GeV possesses no bulk phase transition, its thermodynamics still experiences a “soft point” at temperatures around T=160 GeV, with a deviation from ideal gas thermodynamics. Such a deviation may have an effect on precision computations of weakly interacting dark matter relic abundances if their mass is in the few TeV range, or on leptogenesis scenarios operating in this temperature range. By making use of results from lattice simulations based on a dimensionally reduced effective field theory, we estimate the relevant thermodynamic functions across the crossover. The results are tabulated in a numerical form permitting for their insertion as a background equation of state into cosmological particle production/decoupling codes. We find that Higgs dynamics induces a non-trivial “structure” visible e.g. in the heat capacity, but that in general the largest radiative corrections originate from QCD effects, reducing the energy density by a couple of percent from the free value even at T>160 GeV.
Thermodynamic Modeling of Savannah River Evaporators
Energy Technology Data Exchange (ETDEWEB)
Weber, C.F.
2001-08-02
A thermodynamic model based on the code SOLGASMIX is developed to calculate phase equilibrium in evaporators and related tank wastes at the Savannah River Site (SRS). This model uses the Pitzer method to calculate activity coefficients, and many of the required Pitzer parameters have been determined in the course of this work. Principal chemical species in standard SRS simulant solutions are included, and the temperature range for most parameters has been extended above 100 C. The SOLGASMIX model and calculations using the code Geochemists Workbench are compared to actual solubility data including silicate, aluminate, and aluminosilicate solutions. In addition, SOLGASMIX model calculations are also compared to transient solubility data involving SRS simulant solutions. These comparisons indicate that the SOLGASMIX predictions closely match reliable data over the range of temperature and solution composition expected in the SRS evaporator and related tanks. Predictions using the Geochemists Workbench may be unreliable, due primarily to the use of an inaccurate activity coefficient model.
Thermodynamic modeling of CO2 mixtures
DEFF Research Database (Denmark)
Bjørner, Martin Gamel
performed satisfactorily and predicted the general behavior of the systems, but qCPA used fewer adjustable parameters to achieve similar predictions. It has been demonstrated that qCPA is a promising model which, compared to CPA, systematically improves the predictions of the experimentally determined phase......, accurate predictions of the thermodynamic properties and phase equilibria of mixtures containing CO2 are challenging with classical models such as the Soave-Redlich-Kwong (SRK) equation of state (EoS). This is believed to be due to the fact, that CO2 has a large quadrupole moment which the classical models...... do not explicitly account for. In this thesis, in an attempt to obtain a physically more consistent model, the cubicplus association (CPA) EoS is extended to include quadrupolar interactions. The new quadrupolar CPA (qCPA) can be used with the experimental value of the quadrupolemoment...
Energy Technology Data Exchange (ETDEWEB)
Abergel, Rebecca J.; D' Aleo, Anthony; Ng Pak Leung, Clara; Shuh, David; Raymond, Kenneth
2009-11-20
While widely used in bioassays, the spectrofluorimetric method described here uses the antenna effect as a tool to probe the thermodynamic parameters of ligands that sensitize lanthanide luminescence. The Eu3+ coordination chemistry, solution thermodynamic stability and photophysical properties of the spermine-based hydroxypyridonate octadentate chelator 3,4,3-LI(1,2-HOPO) are reported. The complex [EuIII(3,4,3-LI(1,2-HOPO))]- luminesces with a long lifetime (805 mu s) and a quantum yield of 7.0percent in aqueous solution, at pH 7.4. These remarkable optical properties were exploited to determine the high (and proton-independent) stability of the complex (log beta 110 = 20.2(2)) and to define the influence of the ligand scaffold on the stability and photophysical properties.
Fermi, Enrico
1956-01-01
Indisputably, this is a modern classic of science. Based on a course of lectures delivered by the author at Columbia University, the text is elementary in treatment and remarkable for its clarity and organization. Although it is assumed that the reader is familiar with the fundamental facts of thermometry and calorimetry, no advanced mathematics beyond calculus is assumed.Partial contents: thermodynamic systems, the first law of thermodynamics (application, adiabatic transformations), the second law of thermodynamics (Carnot cycle, absolute thermodynamic temperature, thermal engines), the entr
A thermodynamic model for coal gas outbursts
Energy Technology Data Exchange (ETDEWEB)
Toth, J.; Lakatos, J. (Hungarian Academy of Sciences (Hungary). Research Lab. for Mining Chemistry)
1994-06-01
A thermodynamic model-scheme has been formulated based on the laboratory modelling results of gas/coal outbursts and sorption properties of the gas/coal systems. The sorption properties include the inversion of sorption isotherms, the maximum characters of isobar functions, the activated sorption of gases in coal (methane, carbon-dioxide, nitrogen, ethane) and two equilibria (a metastable and a stable one) in the coal/gas systems. The basic idea of the model is that between the two equilibria exists a potential barrier. When this barrier is crossed by the gas sorbed in the bulk phase of coal a considerable amount of energy is released. This energy may be stored in a definite volume of the rock and if it becomes greater than the compressive strength of the coal the outburst takes place. 4 refs., 5 figs.
Thermodynamic modeling of lead blast furnace
Institute of Scientific and Technical Information of China (English)
TAN Peng-fu
2005-01-01
A thermodynamic model was developed to predict the distribution behavior of Cu,Fe,S,O,Pb,Zn,As,and the heat balance in a lead blast furnace.The modeling results are validated by the plant data of a lead smelter in Kazakhstan.The model can be used to predict any set of controllable process parameters such as feed composition,smelting temperature,degree of oxygen enrichment and volume of oxygen-enriched air.The effects of the blast air,industrial oxygen,and coke charge on the distribution of Cu,Fe,S,O,Pb,Zn,As,the heat balance,and the lead loss in slag,were presented and discussed.
Thermodynamic watershed hydrological model: Constitutive relationship
Institute of Scientific and Technical Information of China (English)
2008-01-01
The representative elementary watershed (REW) approach proposed by Reggiani et al. was the first attempt to develop scale adaptable equations applicable directly at the macro scale. Tian et al. extended the initial definition of REW for simulating the energy related processes, and re-organized the deriving procedure of balance equations so that additional sub-regions and substances could be easily incorpo-rated. The resultant ordinary differential equation set can simulate various hydro-logical processes in a physically reasonable way. However, constitutive and geo-metric relationships have not been developed for Tian et al.’s equation set, which are necessary for the thermodynamic watershed hydrological model to apply in hydrological modeling practice. In this work, the constitutive equations for mass exchange terms and momentum exchange terms were developed as well as geo-metric relationships. The closed ordinary differential equation set with nine equa-tions was finally obtained.
Thermodynamic watershed hydrological model: Constitutive relationship
Institute of Scientific and Technical Information of China (English)
TIAN FuQiang; HU HePing; LEI ZhiDong
2008-01-01
The representative elementary watershed (REW) approach proposed by Reggiani et al. Was the first attempt to develop scale adaptable equations applicable directly at the macro scale. Tian et al. Extended the initial definition of REW for simulating the energy related processes, and re-organized the deriving procedure of balance equations so that additional sub-regions and substances could be easily incorpo- rated. The resultant ordinary differential equation set can simulate various hydro- logical processes in a physically reasonable way. However, constitutive and geo- metric relationships have not been developed for Tian et al.'s equation set, which are necessary for the thermodynamic watershed hydrological model to apply in hydrological modeling practice. In this work, the constitutive equations for mass exchange terms and momentum exchange terms were developed as well as geo- metric relationships. The closed ordinary differential equation set with nine equations was finally obtained.
Calculation of Thermodynamic Parameters for Freundlich and Temkin Isotherm Models
Institute of Scientific and Technical Information of China (English)
ZHANGZENGQIANG; ZHANGYIPING; 等
1999-01-01
Derivation of the Freundlich and Temkin isotherm models from the kinetic adsorption/desorption equations was carried out to calculate their thermodynamic equilibrium constants.The calculation formulase of three thermodynamic parameters,the standard molar Gibbs free energy change,the standard molar enthalpy change and the standard molar entropy change,of isothermal adsorption processes for Freundlich and Temkin isotherm models were deduced according to the relationship between the thermodynamic equilibrium constants and the temperature.
Nonequilibrium Thermodynamic Model of Manganese Carbonate Oxidation
Institute of Scientific and Technical Information of China (English)
郝瑞霞; 彭省临
1999-01-01
Manganese carbonate can be converted to many kinds of manganese oxides when it is aerated in air and oxygen.Pure manganese carbonate can be changed into Mn3O4 and γ-MnOOH,and manganese carbonate ore can be converted to MnO2 under the air-aerating and oxygen-aerating circumstances.The oxidation process of manganese carbonate is a changing process of mineral association,and is also a converting process of valence of manganese itself.Not only equilibrium stat,but also nonequilibrium state are involved in this whole process,This process is an irreversible heterogeneous complex reaction,and oberys the nonequilibrium thermodynamic model,The oxidation rate of manganese cabonate is controlled by many factors,especially nonmanganese metallic ions which play an important role in the oxidation process of manganese carbonate.
A thermodynamic counterpart of the Axelrod model of social influence
Gandica, Y; Bonalde, I
2012-01-01
We propose a thermodynamic version of the Axelrod model of social influence. In one-dimensional lattices, the thermodynamic model becomes a Potts model of several coupled chains with a site (agent) interaction that increases with the site matching traits. We analytically calculate thermodynamic and critical properties for a one-dimensional system and show that an order-disorder phase transition only occurs at T=0 independent of the number of cultural traits q and features F of the agents. We find that the parameter q does not induce any transition or anomaly in the thermodynamic model, as it does in the standard social model that violates detailed balance. The one-dimensional thermodynamic Axelrod model belongs to the same universality class of the Ising and Potts models notwithstanding the increase of the internal dimension of the local degree of freedom (agent).
Climatic and thermodynamic modelling of rapid development drivages
Energy Technology Data Exchange (ETDEWEB)
Crossley, A.J.; Lowndes, I.S. [University of Nottingham (United Kingdom). School of Chemical, Environmental and Mining Engineering
2001-07-01
This paper details the construction of a computer based climatic prediction tool currently being developed at the University of Nottingham. The model predicts the psychrometric and thermodynamic conditions within single entry drivages, taking into account the effects of the strata and the machinery on the ventilation air. The interaction between the air travelling through the forced ventilation ducting and back down the drivage is considered, through a series of leakage and heat transfer calculations. It is intended that the model may be further developed to include procedures to investigate the effects of applying localized cooling systems. Preliminary results obtained from the model are shown and compared against measurements collected from within a UK rapid development drivage. 14 refs., 4 figs.
A constitutive model for magnetostriction based on thermodynamic framework
Ho, Kwangsoo
2016-08-01
This work presents a general framework for the continuum-based formulation of dissipative materials with magneto-mechanical coupling in the viewpoint of irreversible thermodynamics. The thermodynamically consistent model developed for the magnetic hysteresis is extended to include the magnetostrictive effect. The dissipative and hysteretic response of magnetostrictive materials is captured through the introduction of internal state variables. The evolution rate of magnetostrictive strain as well as magnetization is derived from thermodynamic and dissipative potentials in accordance with the general principles of thermodynamics. It is then demonstrated that the constitutive model is competent to describe the magneto-mechanical behavior by comparing simulation results with the experimental data reported in the literature.
Thermodynamic and kinetic modeling of transcriptional pausing.
Tadigotla, Vasisht R; O Maoiléidigh, Dáibhid; Sengupta, Anirvan M; Epshtein, Vitaly; Ebright, Richard H; Nudler, Evgeny; Ruckenstein, Andrei E
2006-03-21
We present a statistical mechanics approach for the prediction of backtracked pauses in bacterial transcription elongation derived from structural models of the transcription elongation complex (EC). Our algorithm is based on the thermodynamic stability of the EC along the DNA template calculated from the sequence-dependent free energy of DNA-DNA, DNA-RNA, and RNA-RNA base pairing associated with (i) the translocational and size fluctuations of the transcription bubble; (ii) changes in the associated DNA-RNA hybrid; and (iii) changes in the cotranscriptional RNA secondary structure upstream of the RNA exit channel. The calculations involve no adjustable parameters except for a cutoff used to discriminate paused from nonpaused complexes. When applied to 100 experimental pauses in transcription elongation by Escherichia coli RNA polymerase on 10 DNA templates, the approach produces statistically significant results. We also present a kinetic model for the rate of recovery of backtracked paused complexes. A crucial ingredient of our model is the incorporation of kinetic barriers to backtracking resulting from steric clashes of EC with the cotranscriptionally generated RNA secondary structure, an aspect not included explicitly in previous attempts at modeling the transcription elongation process.
Thermodynamic modeling of the Co-Fe-O system
DEFF Research Database (Denmark)
Zhang, Weiwei; Chen, Ming
2013-01-01
As a part of the research project aimed at developing a thermodynamic database of the La-Sr-Co-Fe-O system for applications in Solid Oxide Fuel Cells (SOFCs), the Co-Fe-O subsystem was thermodynamically re-modeled in the present work using the CALPHAD methodology. The solid phases were described...
Formulations of moist thermodynamics for atmospheric modelling
Marquet, Pascal
2015-01-01
Internal energy, enthalpy and entropy are the key quantities to study thermodynamic properties of the moist atmosphere, because they correspond to the First (internal energy and enthalpy) and Second (entropy) Laws of thermodynamics. The aim of this chapter is to search for analytical formulas for the specific values of enthalpy and entropy and for the moist-air mixture composing the atmosphere. The Third Law of thermodynamics leads to the definition of absolute reference values for thermal enthalpies and entropies of all atmospheric species. It is shown in this Chapter 22 that it is possible to define and compute a general moist-air entropy potential temperature, which is really an equivalent of the moist-air specific entropy in all circumstances (saturated, or not saturated). Similarly, it is shown that it is possible to define and compute the moist-air specific enthalpy, which is different from the thermal part of what is called Moist-Static-Energy in atmospheric studies.
Molecular Thermodynamic Model for Polyelectrolyte Solutions with Added Salts
Institute of Scientific and Technical Information of China (English)
ZHANGBo; CAIJun; 等
2002-01-01
A molecular thermodynamic model of polyelectrolyte developed previously was extended to polyelectrolyte solutions with added salts.Thermodynamic properties,such as activity coefficients of polyelectrolytes or added salts and osmotic coefficients of solvent, of a number of aqueous mixtures of polyelectrolytes and salts are analyzed with the proposed model.Successful correlation is obtained in the range of moderate or higher polyion concentration.For the same sample,thermodynamic properties of polyelectrolytes with and without simple electrolytes can be predicted mutually using parameters from regression data.
Coupling geodynamic with thermodynamic modelling for reconstructions of magmatic systems
Rummel, Lisa; Kaus, Boris J. P.; White, Richard
2016-04-01
thermodynamic dependent properties from pre-computed phase diagrams are carried by each particle using marker-in-cell method . Thus the physical and chemical properties can change locally as a function of previous melt extraction events, pressure and temperature conditions. After each melt extraction event, the residual rock composition is compared with the bulk composition of previous computed phase diagrams, so that the used phase diagram is replaced by the phase diagram with the closest bulk chemistry. In the thermo-mechanical code, the melt is extracted directly to the surface as volcanites and within the crust as plutonites. The density of the crust and new generated crust is calculated with the thermodynamic modelling tool Perple_X. We have investigated the influence of several input parameters on the magma composition to compare it with real rock samples from Eifel (West-Germany). In order to take the very inhomogeneous chemistry of European mantle into account, we include not only primitive mantle but also metasomatised mantle fragments in the melting source of a plume (Eifel plume).
Kinetic, equilibrium and thermodynamic modelling of the sorption of ...
African Journals Online (AJOL)
Kinetic, equilibrium and thermodynamic modelling of the sorption of metals ... Batch sorption studies were conducted to assess the potential of a ... negative Ea values, indicating their preference to bind to low-energy sites. ... Article Metrics.
Gujrati, P D
2010-05-01
Starting from the second law of thermodynamics applied to an isolated system consisting of the system surrounded by an extremely large medium, we formulate a general nonequilibrium thermodynamic description of the system when it is out of thermal and mechanical equilibrium with the medium. Our approach allows us to identify the correct form of the Gibbs free energy and enthalpy. We also obtain an extension of the classical nonequilibrium thermodynamics due to de Donder in which one normally assumes thermal and mechanical equilibrium with the medium; see text. We find that the temperature and pressure differences between the system and the medium act as thermodynamic forces, which are normally neglected in the classical nonequilibrium thermodynamics. The Prigogine-Defay ratio is found to be greater than 1 merely due to the lack of equilibrium with the medium, even though we do not consider any internal order parameters. This shows that these forces should play an important role in relaxation processes. We then apply our approach to study the general trend during structural relaxation in glasses and establish the phenomenology behind the concept of the fictive temperature and of the empirical Tool-Narayanaswamy equation on firmer theoretical foundation.
Thermodynamic Behavior of particular $f(R,T)$ Gravity Models
Sharif, M
2014-01-01
We investigate the thermodynamics at the apparent horizon of the FRW universe in $f(R,T)$ theory under non-equilibrium description. The laws of thermodynamics have been discussed for two particular models of $f(R,T)$ theory. The first law of thermodynamics is expressed in the form of Clausius relation $T_hd\\hat{S}_h=\\delta{Q}$, where $\\delta{Q}=-d\\hat{E}+Wd\\mathbb{V}+T_hd_{\\jmath}\\hat{S}$ is the energy flux across the horizon and $d_{\\jmath}\\hat{S}$ is the entropy production term. Furthermore, the conditions to preserve the generalized second law of thermodynamics are established with the constraints of positive temperature and attractive gravity. We have illustrated our results for some concrete models in this theory.
Carvalho, Eduardo O.; Araki, Marcelo K.; Freitas, Sergio F.; de Godoy, Carlos M. G.; Faljoni-Alario, Adelaide; Frare-Junior, Pedro L.; Nantes, Iseli L.
2009-01-01
This study describes the application and evaluation of a novel didactic tool (thermodynamic device) developed for students in the area of biology who have conceptual deficiencies that render the learning of thermodynamic principles difficult. Systems of communicant vessels with equal and different compartments were constructed to correlate the…
Evaluation of the Thermodynamic Models for the Thermal Diffusion Factor
DEFF Research Database (Denmark)
Gonzalez-Bagnoli, Mariana G.; Shapiro, Alexander; Stenby, Erling Halfdan
2003-01-01
Over the years, several thermodynamic models for the thermal diffusion factors for binary mixtures have been proposed. The goal of this paper is to test some of these models in combination with different equations of state. We tested the following models: those proposed by Rutherford and Drickame...
A Thermodynamic Point of View on Dark Energy Models
Directory of Open Access Journals (Sweden)
Vincenzo F. Cardone
2017-07-01
Full Text Available We present a conjugate analysis of two different dark energy models, namely the Barboza–Alcaniz parameterization and the phenomenologically-motivated Hobbit model, investigating both their agreement with observational data and their thermodynamical properties. We successfully fit a wide dataset including the Hubble diagram of Type Ia Supernovae, the Hubble rate expansion parameter as measured from cosmic chronometers, the baryon acoustic oscillations (BAO standard ruler data and the Planck distance priors. This analysis allows us to constrain the model parameters, thus pointing at the region of the wide parameters space, which is worth focusing on. As a novel step, we exploit the strong connection between gravity and thermodynamics to further check models’ viability by investigating their thermodynamical quantities. In particular, we study whether the cosmological scenario fulfills the generalized second law of thermodynamics, and moreover, we contrast the two models, asking whether the evolution of the total entropy is in agreement with the expectation for a closed system. As a general result, we discuss whether thermodynamic constraints can be a valid complementary way to both constrain dark energy models and differentiate among rival scenarios.
Thermodynamic modeling of the Au-Sb-Si ternary system
Energy Technology Data Exchange (ETDEWEB)
Wang, J., E-mail: jiang.wang@empa.ch [School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Joining and Interface Technology, Uberlandstrasse 129, Duebendorf, Zuerich CH-8600 (Switzerland); Liu, Y.J. [Western Transportation Institute, Montana State University, Bozeman, MT 59715 (United States); Liu, L.B. [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China); Zhou, H.Y. [School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Jin, Z.P. [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China)
2011-02-10
Research highlights: > Thermodynamic optimization of the Au-Sb binary system was updated. > The Si-Sb binary system was assessed from critical review of experimental information. > Thermodynamic modeling of the Au-Sb-Si ternary system was performed. > The phase relations of this ternary system are useful to design Au-based solders. - Abstract: Thermodynamic optimization of the Au-Sb binary system was updated as well as the Si-Sb binary system was assessed thermodynamically using the CALPHAD method based on the critical review of the available experimental information from the published literature. The solution phases including liquid, fcc{sub A}1(Au), diamond{sub A}4(Si) and rhombohedral{sub A}7(Sb), are modeled as substitutional solutions and their excess Gibbs energies are expressed by a Redlich-Kister polynomial. The solubility of Si in the intermetallic compound AuSb{sub 2} is not taken into account because of the lack of experimental information. Combined with previous assessment of the Au-Si binary system, thermodynamic modeling of the Au-Sb-Si ternary system was performed to reproduce well the measured phase equilibria. The liquidus projection and several vertical sections of this ternary system were calculated, which are in reasonable agreement with the reported experimental data.
Ab Initio Thermodynamic Model for Magnesium Carbonates and Hydrates
Energy Technology Data Exchange (ETDEWEB)
Chaka, Anne M.; Felmy, Andrew R.
2014-03-28
An ab initio thermodynamic framework for predicting properties of hydrated magnesium carbonate minerals has been developed using density-functional theory linked to macroscopic thermodynamics through the experimental chemical potentials for MgO, water, and CO2. Including semiempirical dispersion via the Grimme method and small corrections to the generalized gradient approximation of Perdew, Burke, and Ernzerhof for the heat of formation yields a model with quantitative agreement for the benchmark minerals brucite, magnesite, nesquehonite, and hydromagnesite. The model shows how small differences in experimental conditions determine whether nesquehonite, hydromagnesite, or magnesite is the result of laboratory synthesis from carbonation of brucite, and what transformations are expected to occur on geological time scales. Because of the reliance on parameter-free first principles methods, the model is reliably extensible to experimental conditions not readily accessible to experiment and to any mineral composition for which the structure is known or can be hypothesized, including structures containing defects, substitutions, or transitional structures during solid state transformations induced by temperature changes or processes such as water, CO2, or O2 diffusion. Demonstrated applications of the ab initio thermodynamic framework include an independent means to evaluate differences in thermodynamic data for lansfordite, predicting the properties of Mg analogs of Ca-based hydrated carbonates monohydrocalcite and ikaite which have not been observed in nature, and an estimation of the thermodynamics of barringtonite from the stoichiometry and a single experimental observation.
Ab initio thermodynamic model for magnesium carbonates and hydrates.
Chaka, Anne M; Felmy, Andrew R
2014-09-04
An ab initio thermodynamic framework for predicting properties of hydrated magnesium carbonate minerals has been developed using density-functional theory linked to macroscopic thermodynamics through the experimental chemical potentials for MgO, water, and CO2. Including semiempirical dispersion via the Grimme method and small corrections to the generalized gradient approximation of Perdew, Burke, and Ernzerhof for the heat of formation yields a model with quantitative agreement for the benchmark minerals brucite, magnesite, nesquehonite, and hydromagnesite. The model shows how small differences in experimental conditions determine whether nesquehonite, hydromagnesite, or magnesite is the result of laboratory synthesis from carbonation of brucite, and what transformations are expected to occur on geological time scales. Because of the reliance on parameter-free first-principles methods, the model is reliably extensible to experimental conditions not readily accessible to experiment and to any mineral composition for which the structure is known or can be hypothesized, including structures containing defects, substitutions, or transitional structures during solid state transformations induced by temperature changes or processes such as water, CO2, or O2 diffusion. Demonstrated applications of the ab initio thermodynamic framework include an independent means to evaluate differences in thermodynamic data for lansfordite, predicting the properties of Mg analogues of Ca-based hydrated carbonates monohydrocalcite and ikaite, which have not been observed in nature, and an estimation of the thermodynamics of barringtonite from the stoichiometry and a single experimental observation.
A Thermodynamic Mixed-Solid Asphaltene Precipitation Model
DEFF Research Database (Denmark)
Lindeloff, Niels; Heidemann, R.A.; Andersen, Simon Ivar
1998-01-01
A simple model for the prediction of asphaltene precipitation is proposed. The model is based on an equation of state and uses standard thermodynamics, thus assuming that the precipitation phenomenon is a reversible process. The solid phase is treated as an ideal multicomponent mixture. An activity...
Thermodynamic analysis of regulation in metabolic networks using constraint-based modeling
Directory of Open Access Journals (Sweden)
Mahadevan Radhakrishnan
2010-05-01
Full Text Available Abstract Background Geobacter sulfurreducens is a member of the Geobacter species, which are capable of oxidation of organic waste coupled to the reduction of heavy metals and electrode with applications in bioremediation and bioenergy generation. While the metabolism of this organism has been studied through the development of a stoichiometry based genome-scale metabolic model, the associated regulatory network has not yet been well studied. In this manuscript, we report on the implementation of a thermodynamics based metabolic flux model for Geobacter sulfurreducens. We use this updated model to identify reactions that are subject to regulatory control in the metabolic network of G. sulfurreducens using thermodynamic variability analysis. Findings As a first step, we have validated the regulatory sites and bottleneck reactions predicted by the thermodynamic flux analysis in E. coli by evaluating the expression ranges of the corresponding genes. We then identified ten reactions in the metabolic network of G. sulfurreducens that are predicted to be candidates for regulation. We then compared the free energy ranges for these reactions with the corresponding gene expression fold changes under conditions of different environmental and genetic perturbations and show that the model predictions of regulation are consistent with data. In addition, we also identify reactions that operate close to equilibrium and show that the experimentally determined exchange coefficient (a measure of reversibility is significant for these reactions. Conclusions Application of the thermodynamic constraints resulted in identification of potential bottleneck reactions not only from the central metabolism but also from the nucleotide and amino acid subsystems, thereby showing the highly coupled nature of the thermodynamic constraints. In addition, thermodynamic variability analysis serves as a valuable tool in estimating the ranges of ΔrG' of every reaction in the model
Institute of Scientific and Technical Information of China (English)
胡继敏; 金家善; 严志腾
2013-01-01
The thermodynamic charge performance of a variable-mass thermodynamic system was investigated by the simulation modeling and experimental analysis. Three sets of experiments were conducted for various charge time and charge steam flow under three different control strategies of charge valve. Characteristic performance parameters from the average sub-cooled degree and the charging energy coefficient point of views were also defined to evaluate and predict the charge performance of system combined with the simulation model and experimental data. The results show that the average steam flow reflects the average sub-cooled degree qualitatively, while the charging energy coefficients of 74.6%, 69.9% and 100% relate to the end value of the average sub-cooled degree at 2.1, 2.9 and 0 respectively for the three sets of experiments. The mean and maximum deviations of the results predicted from those by experimental data are smaller than 6.8% and 10.8%, respectively. In conclusion, the decrease of average steam flow can effectively increase the charging energy coefficient in the same charge time condition and therefore improve the thermodynamic charge performance of system. While the increase of the charging energy coefficient by extending the charge time needs the consideration of the operating frequency for steam users.
A THERMODYNAMIC CAVITATION MODEL APPLICABLE TO HIGH TEMPERATURE FLOW
Directory of Open Access Journals (Sweden)
De-Min Liu
2011-01-01
Full Text Available Cavitation is not only related with pressure, but also affected by temperature. Under high temperature, temperature depression of liquids is caused by latent heat of vaporization. The cavitation characteristics under such condition are different from those under room temperature. The paper focuses on thermodynamic cavitation based on the Rayleigh-Plesset equation and modifies the mass transfer equation with fully consideration of the thermodynamic effects and physical properties. To validate the modified model, the external and internal flow fields, such as hydrofoil NACA0015 and nozzle, are calculated, respectively. The hydrofoil NACA0015's cavitation characteristic is calculated by the modified model at different temperatures. The pressure coefficient is found in accordance with the experimental data. The nozzle cavitation under the thermodynamic condition is calculated and compared with the experiment.
Thermodynamic modeling of the Sr-Co-Fe-O system
DEFF Research Database (Denmark)
Zhang, Wei Wei; Povoden-Karadeniz, Erwin; Chen, Ming
2016-01-01
This paper reviews and assesses phase equilibria and thermodynamic properties of phases in the Sr-Co-Fe-O system, with a focus on oxides, especially the SrCo1 - xFexO3 - δ perovskite. In our work, the SrCo1 - xFexO3 - δ perovskite was modeled with a three-sublattice model, where the three...... sublattices correspond to the A, B and oxygen sites in an ABO3 perovskite, respectively. A number of other important ternary oxide phases in Sr-Co-O and Sr-Co-Fe-O were also considered. Available thermodynamic and phase diagram data were carefully assessed. A thermodynamic description of Sr-Co-O was derived...... using the CALPHAD approach and was further extrapolated to that of Sr-Co-Fe-O. The thermodynamic database of Sr-Co-Fe-O established in this work allows for calculating phase diagrams, thermodynamic properties, cation distribution and defect chemistry properties, and therefore enables material...
Vakalis, Stergios; Patuzzi, Francesco; Baratieri, Marco
2016-04-01
Modeling can be a powerful tool for designing and optimizing gasification systems. Modeling applications for small scale/fixed bed biomass gasifiers have been interesting due to their increased commercial practices. Fixed bed gasifiers are characterized by a wide range of operational conditions and are multi-zoned processes. The reactants are distributed in different phases and the products from each zone influence the following process steps and thus the composition of the final products. The present study aims to improve the conventional 'Black-Box' thermodynamic modeling by means of developing multiple intermediate 'boxes' that calculate two phase (solid-vapor) equilibriums in small scale gasifiers. Therefore the model is named ''Multi-Box''. Experimental data from a small scale gasifier have been used for the validation of the model. The returned results are significantly closer with the actual case study measurements in comparison to single-stage thermodynamic modeling.
Thermodynamic modeling and kinetics simulation of precipitate phases in AISI 316 stainless steels
Energy Technology Data Exchange (ETDEWEB)
Yang, Y., E-mail: yangying@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Busby, J.T. [Fusion and Materials for Nuclear Systems Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)
2014-05-01
This work aims at utilizing modern computational microstructural modeling tools to accelerate the understanding of phase stability in austenitic steels under extended thermal aging. Using the CALPHAD approach, a thermodynamic database OCTANT (ORNL Computational Thermodynamics for Applied Nuclear Technology), including elements of Fe, C, Cr, Ni, Mn, Mo, Si, and Ti, has been developed with a focus on reliable thermodynamic modeling of precipitate phases in AISI 316 austenitic stainless steels. The thermodynamic database was validated by comparing the calculated results with experimental data from commercial 316 austenitic steels. The developed computational thermodynamics was then coupled with precipitation kinetics simulation to understand the temporal evolution of precipitates in austenitic steels under long-term thermal aging (up to 600,000 h) at a temperature regime from 300 to 900 °C. This study discusses the effect of dislocation density and difusion coefficients on the precipitation kinetics at low temperatures, which shed a light on investigating the phase stability and transformation in austenitic steels used in light water reactors.
Applications of ArcelorMittal Thermodynamic Computation Tools to Steel Production
Lehmann, Jean
CEQCSI is an ArcelorMittal in-house built thermodynamic equilibrium calculation software which is used both at high temperatures typically for slag-metal reactions but also at "low" temperatures to study solid phase transformations and precipitation in solid steel. It has been built to accommodate different thermodynamic models for slag (the Cell model, the Generalized Central Atom model - product of a collaboration between ArcelorMittal Global R&D Maizieres and CSIRO Melbourne), for steel (sublattice model, Wagner Interaction Parameter Formalism) as well as for oxide, sulfide, carbide… solid solutions. Examples of application concern Si, Mn, S slag-metal equilibrium in Blast-Furnace, P partition in BOF slags, slag-metal equilibrium for flat and long products in ladle… Apart from data relating to mass transfer between different phases at equilibrium, CEQCSI proposes several estimates for slag viscosities with among them one delivered by a new model based on the Generalized Central Atom thermodynamic model for slags. CEQCSI conception allows also handling some kinetic problems such as desulfurization in ladle or slag/metal reaction in mold.
Thermodynamics-based models of transcriptional regulation with gene sequence.
Wang, Shuqiang; Shen, Yanyan; Hu, Jinxing
2015-12-01
Quantitative models of gene regulatory activity have the potential to improve our mechanistic understanding of transcriptional regulation. However, the few models available today have been based on simplistic assumptions about the sequences being modeled or heuristic approximations of the underlying regulatory mechanisms. In this work, we have developed a thermodynamics-based model to predict gene expression driven by any DNA sequence. The proposed model relies on a continuous time, differential equation description of transcriptional dynamics. The sequence features of the promoter are exploited to derive the binding affinity which is derived based on statistical molecular thermodynamics. Experimental results show that the proposed model can effectively identify the activity levels of transcription factors and the regulatory parameters. Comparing with the previous models, the proposed model can reveal more biological sense.
THERMODYNAMIC MODELING AND FIRST-PRINCIPLES CALCULATIONS
Energy Technology Data Exchange (ETDEWEB)
Turchi, P; Abrikosov, I; Burton, B; Fries, S; Grimvall, G; Kaufman, L; Korzhavyi, P; Manga, R; Ohno, M; Pisch, A; Scott, A; Zhang, W
2005-12-15
The increased application of quantum mechanical-based methodologies to the study of alloy stability has required a re-assessment of the field. The focus is mainly on inorganic materials in the solid state. In a first part, after a brief overview of the so-called ab initio methods with their approximations, constraints, and limitations, recommendations are made for a good usage of first-principles codes with a set of qualifiers. Examples are given to illustrate the power and the limitations of ab initio codes. However, despite the ''success'' of these methodologies, thermodynamics of complex multi-component alloys, as used in engineering applications, requires a more versatile approach presently afforded within CALPHAD. Hence, in a second part, the links that presently exist between ab initio methodologies, experiments, and CALPHAD approach are examined with illustrations. Finally, the issues of dynamical instability and of the role of lattice vibrations that still constitute the subject of ample discussions within the CALPHAD community are revisited in the light of the current knowledge with a set of recommendations.
Thermodynamic Modeling and Analysis of Human Stress Response
Boregowda, S. C.; Tiwari, S. N.
1999-01-01
A novel approach based on the second law of thermodynamics is developed to investigate the psychophysiology and quantify human stress level. Two types of stresses (thermal and mental) are examined. A Unified Stress Response Theory (USRT) is developed under the new proposed field of study called Engineering Psychophysiology. The USRT is used to investigate both thermal and mental stresses from a holistic (human body as a whole) and thermodynamic viewpoint. The original concepts and definitions are established as postulates which form the basis for thermodynamic approach to quantify human stress level. An Objective Thermal Stress Index (OTSI) is developed by applying the second law of thermodynamics to the human thermal system to quantify thermal stress or dis- comfort in the human body. The human thermal model based on finite element method is implemented. It is utilized as a "Computational Environmental Chamber" to conduct series of simulations to examine the human thermal stress responses under different environmental conditions. An innovative hybrid technique is developed to analyze human thermal behavior based on series of human-environment interaction simulations. Continuous monitoring of thermal stress is demonstrated with the help of OTSI. It is well established that the human thermal system obeys the second law of thermodynamics. Further, the OTSI is validated against the experimental data. Regarding mental stress, an Objective Mental Stress Index (OMSI) is developed by applying the Maxwell relations of thermodynamics to the combined thermal and cardiovascular system in the human body. The OMSI is utilized to demonstrate the technique of monitoring mental stress continuously and is validated with the help of series of experimental studies. Although the OMSI indicates the level of mental stress, it provides a strong thermodynamic and mathematical relationship between activities of thermal and cardiovascular systems of the human body.
Thermodynamic Model of Aluminum Combustion in SDF Explosions
Energy Technology Data Exchange (ETDEWEB)
Kuhl, . L
2006-06-19
Thermodynamic states encountered during combustion of Aluminum powder in Shock-Dispersed-Fuel (SDF) explosions were analyzed with the Cheetah code. Results are displayed in the Le Chatelier diagram: the locus of states of specific internal energy versus temperature. Accuracy of the results was confirmed by comparing the fuel and products curves with the heats of detonation and combustion, and species composition as measured in bomb calorimeter experiments. Results were fit with analytic functions u = f(T) suitable for specifying the thermodynamic properties required for gas-dynamic models of combustion in explosions.
Thermodynamics of O(N) sigma models : 1/N corrections
Andersen, JO; Boer, D; Warringa, HJ
2004-01-01
The thermodynamics of the O(N) linear and nonlinear sigma models in 3+1 dimensions is studied. We calculate the pressure to next-to-leading order in the 1/N expansion and show that at this order, temperature-independent renormalization is only possible at the minimum of the effective potential. The
WATEQ3 geochemical model: thermodynamic data for several additional solids
Energy Technology Data Exchange (ETDEWEB)
Krupka, K.M.; Jenne, E.A.
1982-09-01
Geochemical models such as WATEQ3 can be used to model the concentrations of water-soluble pollutants that may result from the disposal of nuclear waste and retorted oil shale. However, for a model to competently deal with these water-soluble pollutants, an adequate thermodynamic data base must be provided that includes elements identified as important in modeling these pollutants. To this end, several minerals and related solid phases were identified that were absent from the thermodynamic data base of WATEQ3. In this study, the thermodynamic data for the identified solids were compiled and selected from several published tabulations of thermodynamic data. For these solids, an accepted Gibbs free energy of formation, ..delta..G/sup 0//sub f,298/, was selected for each solid phase based on the recentness of the tabulated data and on considerations of internal consistency with respect to both the published tabulations and the existing data in WATEQ3. For those solids not included in these published tabulations, Gibbs free energies of formation were calculated from published solubility data (e.g., lepidocrocite), or were estimated (e.g., nontronite) using a free-energy summation method described by Mattigod and Sposito (1978). The accepted or estimated free energies were then combined with internally consistent, ancillary thermodynamic data to calculate equilibrium constants for the hydrolysis reactions of these minerals and related solid phases. Including these values in the WATEQ3 data base increased the competency of this geochemical model in applications associated with the disposal of nuclear waste and retorted oil shale. Additional minerals and related solid phases that need to be added to the solubility submodel will be identified as modeling applications continue in these two programs.
Graphical Modeling Language Tool
Rumnit, M.
2003-01-01
The group of the faculty EE-Math-CS of the University of Twente is developing a graphical modeling language for specifying concurrency in software design. This graphical modeling language has a mathematical background based on the theorie of CSP. This language contains the power to create trustworth
DEFF Research Database (Denmark)
Olesen, H. R.
1998-01-01
Proceedings of the Twenty-Second NATO/CCMS International Technical Meeting on Air Pollution Modeling and Its Application, held June 6-10, 1997, in Clermont-Ferrand, France.......Proceedings of the Twenty-Second NATO/CCMS International Technical Meeting on Air Pollution Modeling and Its Application, held June 6-10, 1997, in Clermont-Ferrand, France....
A unified viscoplasticity constitutive model based on irreversible thermodynamics
Institute of Scientific and Technical Information of China (English)
LIU ChangChun; LV HeXiang; GUAN Ping
2008-01-01
A unified viscoplasticity constitutive model for metal materials is developed within the framework of irreversible thermodynamics, and an expression for the Helmholtz free energy function involving the parameters reflecting kinematic hardening and isotropic hardening is given. At the same time a non-associated flow potential function including the corresponding state variables is also given, from which the flow equation and the evolution equations of the internal state variables are derived. Thus, a general theoretical framework constructing a unified viscoplasticity con-stitutive model is given. Compared with the typical unified viscoplasticity constitu-tive models, the presented model evidently satisfies the irreversible thermody-namics laws. Moreover, this method not only provides a new theoretical foundation for further development of the unified viscoplasticity constitutive model, but also gives a new theoretical framework for the stress-strain analysis of more materials.
Simulation of styrene polymerization reactors: kinetic and thermodynamic modeling
Directory of Open Access Journals (Sweden)
A. S. Almeida
2008-06-01
Full Text Available A mathematical model for the free radical polymerization of styrene is developed to predict the steady-state and dynamic behavior of a continuous process. Special emphasis is given for the kinetic and thermodynamic models, where the most sensitive parameters were estimated using data from an industrial plant. The thermodynamic model is based on a cubic equation of state and a mixing rule applied to the low-pressure vapor-liquid equilibrium of polymeric solutions, suitable for modeling the auto-refrigerated polymerization reactors, which use the vaporization rate to remove the reaction heat from the exothermic reactions. The simulation results show the high predictive capability of the proposed model when compared with plant data for conversion, average molecular weights, polydispersity, melt flow index, and thermal properties for different polymer grades.
A unified viscoplasticity constitutive model based on irreversible thermodynamics
Institute of Scientific and Technical Information of China (English)
2008-01-01
A unified viscoplasticity constitutive model for metal materials is developed within the framework of irreversible thermodynamics, and an expression for the Helmholtz free energy function involving the parameters reflecting kinematic hardening and isotropic hardening is given. At the same time a non-associated flow potential function including the corresponding state variables is also given, from which the flow equation and the evolution equations of the internal state variables are derived. Thus, a general theoretical framework constructing a unified viscoplasticity constitutive model is given. Compared with the typical unified viscoplasticity constitutive models, the presented model evidently satisfies the irreversible thermodynamics laws. Moreover, this method not only provides a new theoretical foundation for further development of the unified viscoplasticity constitutive model, but also gives a new theoretical framework for the stress-strain analysis of more materials.
Thermodynamic and Kinetic Modeling of Transcriptional Pausing
National Research Council Canada - National Science Library
Vasisht R. Tadigotla; Dáibhid Ó. Maoiléidigh; Anirvan M. Sengupta; Vitaly Epshtein; Richard H. Ebright; Evgeny Nudler; Andrei E. Ruckenstein
2006-01-01
We present a statistical mechanics approach for the prediction of backtracked pauses in bacterial transcription elongation derived from structural models of the transcription elongation complex (EC...
anNET: a tool for network-embedded thermodynamic analysis of quantitative metabolome data
Directory of Open Access Journals (Sweden)
Zamboni Nicola
2008-04-01
Full Text Available Abstract Background Compared to other omics techniques, quantitative metabolomics is still at its infancy. Complex sample preparation and analytical procedures render exact quantification extremely difficult. Furthermore, not only the actual measurement but also the subsequent interpretation of quantitative metabolome data to obtain mechanistic insights is still lacking behind the current expectations. Recently, the method of network-embedded thermodynamic (NET analysis was introduced to address some of these open issues. Building upon principles of thermodynamics, this method allows for a quality check of measured metabolite concentrations and enables to spot metabolic reactions where active regulation potentially controls metabolic flux. So far, however, widespread application of NET analysis in metabolomics labs was hindered by the absence of suitable software. Results We have developed in Matlab a generalized software called 'anNET' that affords a user-friendly implementation of the NET analysis algorithm. anNET supports the analysis of any metabolic network for which a stoichiometric model can be compiled. The model size can span from a single reaction to a complete genome-wide network reconstruction including compartments. anNET can (i test quantitative data sets for thermodynamic consistency, (ii predict metabolite concentrations beyond the actually measured data, (iii identify putative sites of active regulation in the metabolic reaction network, and (iv help in localizing errors in data sets that were found to be thermodynamically infeasible. We demonstrate the application of anNET with three published Escherichia coli metabolome data sets. Conclusion Our user-friendly and generalized implementation of the NET analysis method in the software anNET allows users to rapidly integrate quantitative metabolome data obtained from virtually any organism. We envision that use of anNET in labs working on quantitative metabolomics will provide the
CALPHAD formalism for Portland clinker: thermodynamic models and databases
De Noirfontaine, Marie-Noëlle; Tusseau-Nenez, Sandrine; Girod-Labianca, Caroline; Pontikis, V.
2012-01-01
International audience; The so-called CALPHAD method is widely used in metallurgy to predict phase diagrams of multi-component systems. The application of the method to oxide systems is much more recent, because of the difficulty of modelling the ionic liquid phase. Since the 1980s, several models have been proposed by various communities. Thermodynamic databases for oxides are available and still under development. The purpose of this article is to discuss the distinct approaches of the meth...
Integrated thermodynamic model for ignition target performance
Directory of Open Access Journals (Sweden)
Springer P.T.
2013-11-01
Full Text Available We have derived a 3-dimensional synthetic model for NIF implosion conditions, by predicting and optimizing fits to a broad set of x-ray and nuclear diagnostics obtained on each shot. By matching x-ray images, burn width, neutron time-of-flight ion temperature, yield, and fuel ρr, we obtain nearly unique constraints on conditions in the hotspot and fuel in a model that is entirely consistent with the observables. This model allows us to determine hotspot density, pressure, areal density (ρr, total energy, and other ignition-relevant parameters not available from any single diagnostic. This article describes the model and its application to National Ignition Facility (NIF tritium–hydrogen–deuterium (THD and DT implosion data, and provides an explanation for the large yield and ρr degradation compared to numerical code predictions.
Thermodynamics and phase structure of the Polyakov-Quark-Meson model
Energy Technology Data Exchange (ETDEWEB)
Braun, Jens [Institut fuer Kernphysik (Theoriezentrum), Technische Universitaet Darmstadt (Germany); ExtreMe Matter Institute EMMI, GSI (Germany); Fraga, Eduardo S. [Instituto de Fisica, Universidade Federal do Rio de Janeiro (Brazil); Institut fuer Theoretische Physik, Goethe-Universitaet Frankfurt (Germany); Haas, Lisa M.; Pawlowski, Jan M. [Institut fuer Theoretische Physik, Universitaet Heidelberg (Germany); ExtreMe Matter Institute EMMI, GSI (Germany); Herbst, Tina K.; Stiele, Rainer [Institut fuer Theoretische Physik, Universitaet Heidelberg (Germany); Mintz, Bruno W.; Ramos, Rudnei O. [Departamento de Fisica Teorica, Universidade do Estado do Rio de Janeiro (Brazil); Mitter, Mario [Institut fuer Theoretische Physik, Universitaet Heidelberg (Germany); Institut fuer Theoretische Physik, Goethe-Universitaet Frankfurt (Germany); Schaefer, Bernd-Jochen [Institut fuer Theoretische Physik, Justus-Liebig-Universitaet Giessen (Germany); Institut fuer Physik, Karl-Franzens-Universitaet Graz (Austria); Schaffner-Bielich, Juergen [Institut fuer Theoretische Physik, Goethe-Universitaet Frankfurt (Germany)
2014-07-01
Polyakov-loop extended chiral effective models are important tools to describe the phase structure and thermodynamics of strongly interacting matter. We show that taking into account the backreaction of quarks onto the gauge sector is crucial in such models to achieve results for the order parameters and thermodynamics that are in line with lattice calculations. Achieving a good description of lattice data at zero density, we test the reliability of those models in systems containing other control parameters besides the temperature by confronting its results with lattice data at nonzero isospin. Furthermore, we investigate the phase structure of the three-dimensional T-μ{sub isospin}-μ{sub quark} phase diagram and calculate the surface tension of the first order phase transition at small temperatures and large quark densities.
On the ternary Ag – Cu – Ga system: Electromotive force measurement and thermodynamic modeling
Energy Technology Data Exchange (ETDEWEB)
Gierlotka, Wojciech, E-mail: wojtek@mail.ndhu.edu.tw [Materials Science and Engineering Department, National Dong Hwa University, Hualien, Taiwan (China); Jendrzejczyk-Handzlik, Dominika; Fitzner, Krzysztof; Handzlik, Piotr [Non-Ferrous Metals Department, AGH University of Science and Technology, Krakow (Poland)
2015-10-15
The ternary silver–copper–gallium system found application as a solder material in jewel crafting and electronics, thus a phase diagram of this system seems to be important tool, which is necessary for a proper application of different alloys. The activity of gallium in liquid phase was determined by electromotive measurement technique and after that the equilibrium diagram of Ag – Cu – Ga was modeled based on available experimental data using Calphad approach. A set of Gibbs energies was found and used for calculation a phase diagram and thermodynamic properties of liquid phase. The experimental data was reproduced well by calculation. - Highlights: • For the first time activity of Ga in liquid Ag – Cu – Ga alloys was measured. • For the first time the ternary Ag – Cu – Ga system was thermodynamically modeled. • Modeled Ag – Cu – Ga system reproduces experimental data well.
Emergent Dynamics of a Thermodynamically Consistent Particle Model
Ha, Seung-Yeal; Ruggeri, Tommaso
2017-03-01
We present a thermodynamically consistent particle (TCP) model motivated by the theory of multi-temperature mixture of fluids in the case of spatially homogeneous processes. The proposed model incorporates the Cucker-Smale (C-S) type flocking model as its isothermal approximation. However, it is more complex than the C-S model, because the mutual interactions are not only " mechanical" but are also affected by the "temperature effect" as individual particles may exhibit distinct internal energies. We develop a framework for asymptotic weak and strong flocking in the context of the proposed model.
Thermodynamic characterisation and modelling of coal liquids
Veen, A.M.H. van der
1997-01-01
For the description of the temperature-pressure relationship of coal oils, a model is required that requires as input only data from analytical chemical techniques. Coal oils are obtained during liquefaction and differ in properties from crude oils in their contents of aromatic hydrocarbons. As
Energy Technology Data Exchange (ETDEWEB)
Rock, P.A.
1983-01-01
This book, suitable as an introductory text for undergraduates, presents temperature, internal energy, and entropy with a minimum of mathematics. The basic mathematical models of classical chemical thermodynamics are developed later in the text. Includes numerous problems at the end of each chapter, an appendix giving thermodynamic data for common substances, a short list of references, answers to selected problems, and a subject index. Contents, abridged: Energy and the first law of thermodynamics. Thermodynamic functions. The third law of thermodynamics and absolute entropies. Thermodynamics of chemical reactions. Phase equilibria: the activity function. Thermodynamics of ions in solution. Statistical thermodynamics. Appendices. Index.
Building Qualitative Models of Thermodynamic Processes
2007-01-01
two containers 61 53 Envisionment for simple flow with thermal properties 62 54 Envisionment for simple flow without thermal properties 63 55 A...pump and a path connecting two containers 64 56 Scenario input for a pump and a return path between two containers . . 64 57 Envisionment for the...Specifically, the domain model is written in the language of QPE[8], an envisioner for Qualitative Process theory . We assume a reading knowledge of QP theory
Thermodynamical aspects of running vacuum models
Energy Technology Data Exchange (ETDEWEB)
Lima, J.A.S. [Universidade de Sao Paulo, Departamento de Astronomia, Sao Paulo (Brazil); Basilakos, Spyros [Academy of Athens, Research Center for Astronomy and Applied Mathematics, Athens (Greece); Sola, Joan [Univ. de Barcelona, High Energy Physics Group, Dept. d' Estructura i Constituents de la Materia, Institut de Ciencies del Cosmos (ICC), Barcelona, Catalonia (Spain)
2016-04-15
The thermal history of a large class of running vacuum models in which the effective cosmological term is described by a truncated power series of the Hubble rate, whose dominant term is Λ(H) ∝ H{sup n+2}, is discussed in detail. Specifically, by assuming that the ultrarelativistic particles produced by the vacuum decay emerge into space-time in such a way that its energy density ρ{sub r} ∝ T{sup 4}, the temperature evolution law and the increasing entropy function are analytically calculated. For the whole class of vacuum models explored here we find that the primeval value of the comoving radiation entropy density (associated to effectively massless particles) starts from zero and evolves extremely fast until reaching a maximum near the end of the vacuum decay phase, where it saturates. The late-time conservation of the radiation entropy during the adiabatic FRW phase also guarantees that the whole class of running vacuum models predicts the same correct value of the present day entropy, S{sub 0} ∝ 10{sup 87}-10{sup 88} (in natural units), independently of the initial conditions. In addition, by assuming Gibbons¨CHawking temperature as an initial condition, we find that the ratio between the late-time and primordial vacuum energy densities is in agreement with naive estimates from quantum field theory, namely, ρ{sub Λ0}/ρ{sub ΛI} 10{sup -123}. Such results are independent on the power n and suggests that the observed Universe may evolve smoothly between two extreme, unstable, non-singular de Sitter phases. (orig.)
Negative specific heat in a thermodynamic model of multifragmentation
Das, C B; Mekjian, A Z
2003-01-01
We consider a soluble model of multifragmentation which is similar in spirit to many models which have been used to fit intermediate energy heavy ion collision data. In this model $c_v$ is always positive but for finite nuclei $c_p$ can be negative for some temperatures and pressures. Furthermore, negative values of $c_p$ can be obtained in canonical treatment. One does not need to use the microcanonical ensemble. Negative values for $c_p$ can persist for systems as large as 200 paticles but this depends upon parameters used in the model calculation. As expected, negative specific heats are absent in the thermodynamic limit.
Advances on statistical/thermodynamical models for unpolarized structure functions
Trevisan, Luis A.; Mirez, Carlos; Tomio, Lauro
2013-03-01
During the eights and nineties many statistical/thermodynamical models were proposed to describe the nucleons' structure functions and distribution of the quarks in the hadrons. Most of these models describe the compound quarks and gluons inside the nucleon as a Fermi / Bose gas respectively, confined in a MIT bag[1] with continuous energy levels. Another models considers discrete spectrum. Some interesting features of the nucleons are obtained by these models, like the sea asymmetries ¯d/¯u and ¯d-¯u.
A thermodynamic model of contact angle hysteresis
Makkonen, Lasse
2017-08-01
When a three-phase contact line moves along a solid surface, the contact angle no longer corresponds to the static equilibrium angle but is larger when the liquid is advancing and smaller when the liquid is receding. The difference between the advancing and receding contact angles, i.e., the contact angle hysteresis, is of paramount importance in wetting and capillarity. For example, it determines the magnitude of the external force that is required to make a drop slide on a solid surface. Until now, fundamental origin of the contact angle hysteresis has been controversial. Here, this origin is revealed and a quantitative theory is derived. The theory is corroborated by the available experimental data for a large number of solid-liquid combinations. The theory is applied in modelling the contact angle hysteresis on a textured surface, and these results are also in quantitative agreement with the experimental data.
Developing and assessing research-based tools for teaching quantum mechanics and thermodynamics
Brown, Benjamin R.
Research-based tools to educate college students in physics courses from introductory level to graduate level are essential for helping students with a diverse set of goals and backgrounds learn physics. This thesis explores issues related to student common difficulties with some topics in undergraduate quantum mechanics and thermodynamics courses. Student difficulties in learning quantum mechanics and thermodynamics are investigated by administering written tests and surveys to many classes and conducting individual interviews with a subset of students outside the class to unpack the cognitive mechanisms of the difficulties. The quantum mechanics research also focuses on using the research on student difficulties for the development and evaluation of a Quantum Interactive Learning Tutorial (QuILT) to help students learn about the time-dependence of expectation values using the context of Larmor precession of spin and evaluating the role of asking students to self-diagnose their mistakes on midterm examination on their performance on subsequent problem solving. The QuILT on Larmor precession of spin has both paper-pencil activities and a simulation component to help students learn these foundational issues in quantum mechanics. Preliminary evaluations suggest that the QuILT, which strives to help students build a robust knowledge structure of time-dependence of expectation values in quantum mechanics using a guided approach, is successful in helping students learn these topics in the junior-senior level quantum mechanics courses. The technique to help upper-level students in quantum mechanics courses effectively engage in the process of learning from their mistakes is also found to be effective. In particular, research shows that the self-diagnosis activity in upper-level quantum mechanics significantly helps students who are struggling and this activity can reduce the gap between the high and low achieving students on subsequent problem solving. Finally, a survey
Statistical thermodynamics concepts and mathematical tools for a multi-agent ecosystem.
Segovia, Javier
2014-01-01
Finding the distribution of systems over their possible states is a mathematical problem. One possible solution is the method of the most probable distribution developed by Boltzmann. This method has been instrumental in developing statistical mechanics and explaining the origin of many thermodynamics concepts, like entropy or temperature, but is also applicable in many other fields like ecology or economics. Artificial ecosystems have many features in common with ecological or economic systems, but surprisingly the method does not appear to have been very successful in this field of application. The hypothesis of this article is that this failure is due to the incorrect interpretation of the method's concepts and mathematical tools. We propose to review and reinterpret the method so that it can be correctly applied and all its potential exploited in order to study and characterize the global behavior of an artificial multi-agent ecosystem.
A Thermodynamic Model for Genome Packaging in Hepatitis B Virus.
Kim, Jehoon; Wu, Jianzhong
2015-10-20
Understanding the fundamentals of genome packaging in viral capsids is important for finding effective antiviral strategies and for utilizing benign viral particles for gene therapy. While the structure of encapsidated genomic materials has been routinely characterized with experimental techniques such as cryo-electron microscopy and x-ray diffraction, much less is known about the molecular driving forces underlying genome assembly in an intracellular environment and its in vivo interactions with the capsid proteins. Here we study the thermodynamic basis of the pregenomic RNA encapsidation in human Hepatitis B virus in vivo using a coarse-grained molecular model that captures the essential components of nonspecific intermolecular interactions. The thermodynamic model is used to examine how the electrostatic interaction between the packaged RNA and the highly charged C-terminal domains (CTD) of capsid proteins regulate the nucleocapsid formation. The theoretical model predicts optimal RNA content in Hepatitis B virus nucleocapsids with different CTD lengths in good agreement with mutagenesis measurements, confirming the predominant role of electrostatic interactions and molecular excluded-volume effects in genome packaging. We find that the amount of encapsidated RNA is not linearly correlated with the net charge of CTD tails as suggested by earlier theoretical studies. Our thermodynamic analysis of the nucleocapsid structure and stability indicates that ∼10% of the CTD residues are free from complexation with RNA, resulting in partially exposed CTD tails. The thermodynamic model also predicts the free energy of complex formation between macromolecules, which corroborates experimental results for the impact of CTD truncation on the nucleocapsid stability.
Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS) User's Guide
Chapman, Jeffryes W.; Lavelle, Thomas M.; May, Ryan D.; Litt, Jonathan S.; Guo, Ten-Huei
2014-01-01
The Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS) software package is an open source, MATLABSimulink toolbox (plug in) that can be used by industry professionals and academics for the development of thermodynamic and controls simulations.
Integrated stoichiometric, thermodynamic and kinetic modelling of steady state metabolism.
Fleming, R M T; Thiele, I; Provan, G; Nasheuer, H P
2010-06-07
The quantitative analysis of biochemical reactions and metabolites is at frontier of biological sciences. The recent availability of high-throughput technology data sets in biology has paved the way for new modelling approaches at various levels of complexity including the metabolome of a cell or an organism. Understanding the metabolism of a single cell and multi-cell organism will provide the knowledge for the rational design of growth conditions to produce commercially valuable reagents in biotechnology. Here, we demonstrate how equations representing steady state mass conservation, energy conservation, the second law of thermodynamics, and reversible enzyme kinetics can be formulated as a single system of linear equalities and inequalities, in addition to linear equalities on exponential variables. Even though the feasible set is non-convex, the reformulation is exact and amenable to large-scale numerical analysis, a prerequisite for computationally feasible genome scale modelling. Integrating flux, concentration and kinetic variables in a unified constraint-based formulation is aimed at increasing the quantitative predictive capacity of flux balance analysis. Incorporation of experimental and theoretical bounds on thermodynamic and kinetic variables ensures that the predicted steady state fluxes are both thermodynamically and biochemically feasible. The resulting in silico predictions are tested against fluxomic data for central metabolism in Escherichia coli and compare favourably with in silico prediction by flux balance analysis.
Multiensemble Markov models of molecular thermodynamics and kinetics.
Wu, Hao; Paul, Fabian; Wehmeyer, Christoph; Noé, Frank
2016-06-07
We introduce the general transition-based reweighting analysis method (TRAM), a statistically optimal approach to integrate both unbiased and biased molecular dynamics simulations, such as umbrella sampling or replica exchange. TRAM estimates a multiensemble Markov model (MEMM) with full thermodynamic and kinetic information at all ensembles. The approach combines the benefits of Markov state models-clustering of high-dimensional spaces and modeling of complex many-state systems-with those of the multistate Bennett acceptance ratio of exploiting biased or high-temperature ensembles to accelerate rare-event sampling. TRAM does not depend on any rate model in addition to the widely used Markov state model approximation, but uses only fundamental relations such as detailed balance and binless reweighting of configurations between ensembles. Previous methods, including the multistate Bennett acceptance ratio, discrete TRAM, and Markov state models are special cases and can be derived from the TRAM equations. TRAM is demonstrated by efficiently computing MEMMs in cases where other estimators break down, including the full thermodynamics and rare-event kinetics from high-dimensional simulation data of an all-atom protein-ligand binding model.
Thermodynamics of Paint Related Systems with Engineering Models
DEFF Research Database (Denmark)
Lindvig, Thomas; Michelsen, Michael Locht; Kontogeorgis, Georgios
2001-01-01
Paints are complex materials composed of polymers (binders) dissolved in one or more solvents, pigments, and other additives. The thermodynamics of such systems is essential, for example, for selecting improved solvents and understanding a number of phenomena related especially! to adhesion...... to solid surfaces and drying. Many engineering models have been applied over the last decades for solutions with commoditity polymers. In this work the performance of some of these models is investigated for paint-related systems, focusing on those drying by the so-called " lacquer mechanism " (evaporation...
Simple thermodynamic model for the hydrogen phase diagram
Magdǎu, Ioan B.; Marqués, Miriam; Borgulya, Balint; Ackland, Graeme J.
2017-03-01
We describe a classical thermodynamic model that reproduces the main features of the solid hydrogen phase diagram. In particular, we show how the general structure types, which are found by electronic structure calculations and the quantum nature of the protons, can also be understood from a classical viewpoint. The model provides a picture not only of crystal structure, but also for the anomalous melting curve and insights into isotope effects, liquid metallisation, and infrared activity. The existence of a classical picture for this most quantum of condensed matter systems provides a surprising extension of the correspondence principle of quantum mechanics, in particular the equivalent effects of classical and quantum uncertainty.
A Zeroth Law Compatible Model to Kerr Black Hole Thermodynamics
Directory of Open Access Journals (Sweden)
Viktor G. Czinner
2017-02-01
Full Text Available We consider the thermodynamic and stability problem of Kerr black holes arising from the nonextensive/nonadditive nature of the Bekenstein–Hawking entropy formula. Nonadditive thermodynamics is often criticized by asserting that the zeroth law cannot be compatible with nonadditive composition rules, so in this work we follow the so-called formal logarithm method to derive an additive entropy function for Kerr black holes also satisfying the zeroth law’s requirement. Starting from the most general, equilibrium compatible, nonadditive entropy composition rule of Abe, we consider the simplest non-parametric approach that is generated by the explicit nonadditive form of the Bekenstein–Hawking formula. This analysis extends our previous results on the Schwarzschild case, and shows that the zeroth law-compatible temperature function in the model is independent of the mass–energy parameter of the black hole. By applying the Poincaré turning point method, we also study the thermodynamic stability problem in the system.
Energy Technology Data Exchange (ETDEWEB)
Morrison, J.L.
1992-12-01
The objective of this research is to develop a simple, yet accurate, lumped parameter mathematical model for an explosively driven magnetohydrodynamic generator that can predict the pulse power variables of voltage and current from startup through regenerative operation. The inputs to the model will be the plasma properties entering the generator as predicted by the explosive shock model of Reference [1]. The strategy used was to simplify electromagnetic and thermodynamic three dimensional effects into a zero dimensional model. The model will provide a convenient tool for researchers to optimize designs to be used in pulse power applications. The model is validated using experimental data of Reference [1]. An overview of the operation of the explosively driven generator is first presented. Then a simplified electrical circuit model that describes basic performance of the device is developed. Then a lumped parameter model that incorporates the coupled electromagnetic and thermodynamic effects that govern generator performance is described and developed. The model is based on fundamental physical principles and parameters that were either obtained directly from design data or estimated from experimental data. The model was used to obtain parameter sensitivities and predict beyond the limits observed in the experiments to the levels desired by the potential Department of Defense sponsors. The model identifies process limitations that provide direction for future research.
Thermodynamic Modeling of the Al-Cr-Mn Ternary System
Cui, Senlin; Jung, In-Ho
2017-03-01
The phase diagram information available in the literature on the Al-Cr-Mn system was comprehensively evaluated and optimized for the first time to obtain a set of Gibbs energies of all the solid and liquid phases in the Al-Cr-Mn system. The Modified Quasi-chemical Model (MQM) was utilized to describe the Gibbs energy of the liquid phase of the Al-Cr-Mn system. The Compound Energy Formalism (CEF) was used to model the solid solution phases. A revision of the Al-Mn system was simultaneously conducted to consider the γ_H (Al8Mn5) phase. The liquid Cr-Mn phase was also remodeled using the Modified Quasi-chemical Model (MQM) to obtain a consistent description of the ternary Al-Cr-Mn liquid phase. Accurate description of the phase diagram of the entire Al-Cr-Mn system was obtained from the thermodynamic models with optimized parameters in the present study, and the model parameters can be used to predict the thermodynamic properties of the ternary system.
Integrating a Decision Management Tool with UML Modeling Tools
DEFF Research Database (Denmark)
Könemann, Patrick
Numerous design decisions are made while developing software systems, which influence the architecture of these systems as well as following decisions. A number of decision management tools already exist for capturing, documenting, and maintaining design decisions, but also for guiding developers...... the development process. In this report, we propose an integration of a decision management and a UML-based modeling tool, based on use cases we distill from a case study: the modeling tool shall show all decisions related to a model and allow its users to extend or update them; the decision management tool shall...... trigger the modeling tool to realize design decisions in the models. We define tool-independent concepts and architecture building blocks supporting these use cases and present how they can be implemented in the IBM Rational Software Modeler and Architectural Decision Knowledge Wiki. This seamless...
Thermodynamic properties of lattice hard-sphere models.
Panagiotopoulos, A Z
2005-09-08
Thermodynamic properties of several lattice hard-sphere models were obtained from grand canonical histogram- reweighting Monte Carlo simulations. Sphere centers occupy positions on a simple cubic lattice of unit spacing and exclude neighboring sites up to a distance sigma. The nearestneighbor exclusion model, sigma = radical2, was previously found to have a second-order transition. Models with integer values of sigma = 1 or 2 do not have any transitions. Models with sigma = radical3 and sigma = 3 have weak first-order fluid-solid transitions while those with sigma = 2 radical2, 2 radical3, and 3 radical2 have strong fluid-solid transitions. Pressure, chemical potential, and density are reported for all models and compared to the results for the continuum, theoretical predictions, and prior simulations when available.
Thermodynamic Modeling of Natural Gas Systems Containing Water
DEFF Research Database (Denmark)
Karakatsani, Eirini K.; Kontogeorgis, Georgios M.
2013-01-01
with a heavy phase were previously obtained using cubic plus association (CPA) coupled with a solid phase model in the case of hydrates, for the binary systems of water–methane and water–nitrogen and a few natural gas mixtures. In this work, CPA is being validated against new experimental data, both water...... content and phase equilibrium data, and solid model parameters are being estimated for four natural gas main components (methane, ethane, propane, and carbon dioxide). Different tests for the solid model parameters are reported, including vapor-hydrate-equilibria (VHE) and liquid-hydrate-equilibria (LHE......As the need for dew point specifications remains very urgent in the natural gas industry, the development of accurate thermodynamic models, which will match experimental data and will allow reliable extrapolations, is needed. Accurate predictions of the gas phase water content in equilibrium...
Thermodynamic models for bounding pressurant mass requirements of cryogenic tanks
Vandresar, Neil T.; Haberbusch, Mark S.
1994-01-01
Thermodynamic models have been formulated to predict lower and upper bounds for the mass of pressurant gas required to pressurize a cryogenic tank and then expel liquid from the tank. Limiting conditions are based on either thermal equilibrium or zero energy exchange between the pressurant gas and initial tank contents. The models are independent of gravity level and allow specification of autogenous or non-condensible pressurants. Partial liquid fill levels may be specified for initial and final conditions. Model predictions are shown to successfully bound results from limited normal-gravity tests with condensable and non-condensable pressurant gases. Representative maximum collapse factor maps are presented for liquid hydrogen to show the effects of initial and final fill level on the range of pressurant gas requirements. Maximum collapse factors occur for partial expulsions with large final liquid fill fractions.
Thermodynamically consistent model of brittle oil shales under overpressure
Izvekov, Oleg
2016-04-01
The concept of dual porosity is a common way for simulation of oil shale production. In the frame of this concept the porous fractured media is considered as superposition of two permeable continua with mass exchange. As a rule the concept doesn't take into account such as the well-known phenomenon as slip along natural fractures, overpressure in low permeability matrix and so on. Overpressure can lead to development of secondary fractures in low permeability matrix in the process of drilling and pressure reduction during production. In this work a new thermodynamically consistent model which generalizes the model of dual porosity is proposed. Particularities of the model are as follows. The set of natural fractures is considered as permeable continuum. Damage mechanics is applied to simulation of secondary fractures development in low permeability matrix. Slip along natural fractures is simulated in the frame of plasticity theory with Drucker-Prager criterion.
Thermodynamic Development of Corrosion Rate Modeling in Iron Phosphate Glasses
Energy Technology Data Exchange (ETDEWEB)
Schlesinger, Mark [Missouri Univ. of Science and Technology, Rolla, MO (United States); Brow, Richard [Missouri Univ. of Science and Technology, Rolla, MO (United States)
2011-10-31
A two-year research program investigated links between the thermodynamic properties of phosphate glasses and their corrosion rates in different solutions. Glasses in the Na_{2}O-CaO-P_{2}O_{5} and Na_{2}O-Fe_{2}O_{3}-PO_{5} systems were prepared and characterized. These glasses were then exposed in bulk and powder form to acid (0.1M HCl), basic (0.1M KOH) and neutral (deionized water) solutions at varying exposure times and temperatures. Analysis of the solution and the glass after exposure determined the rate and type of corrosion that occurred. Simultaneously, efforts were made to determine the thermodynamic properties of solid iron phosphate compounds. This included measurement of low temperature (5-300 K) heat capacities, measured at Brigham Young University; the attempted use of a Parr calorimeter to measure ambient temperature enthalpies of formation; and attempted measurement of temperature heat capacities. Only the first of the three tasks was successfully accomplished. In lieu of experimental measurement of enthalpies of formation, first-principles calculation of enthalpies of formation was performed at Missouri S&T; these results will be used in subsequent modeling efforts.
On the thermodynamic properties of the generalized Gaussian core model
Directory of Open Access Journals (Sweden)
B.M.Mladek
2005-01-01
Full Text Available We present results of a systematic investigation of the properties of the generalized Gaussian core model of index n. The potential of this system interpolates via the index n between the potential of the Gaussian core model and the penetrable sphere system, thereby varying the steepness of the repulsion. We have used both conventional and self-consistent liquid state theories to calculate the structural and thermodynamic properties of the system; reference data are provided by computer simulations. The results indicate that the concept of self-consistency becomes indispensable to guarantee excellent agreement with simulation data; in particular, structural consistency (in our approach taken into account via the zero separation theorem is obviously a very important requirement. Simulation results for the dimensionless equation of state, β P / ρ, indicate that for an index-value of 4, a clustering transition, possibly into a structurally ordered phase might set in as the system is compressed.
A Thermodynamic Model for Argon Plasma Kernel Formation
Directory of Open Access Journals (Sweden)
James Keck
2010-11-01
Full Text Available Plasma kernel formation of argon is studied experimentally and theoretically. The experiments have been performed in a constant volume cylindrical vessel located in a shadowgraph system. The experiments have been done in constant pressure. The energy of plasma is supplied by an ignition system through two electrodes located in the vessel. The experiments have been done with two different spark energies to study the effect of input energy on kernel growth and its properties. A thermodynamic model employing mass and energy balance was developed to predict the experimental data. The agreement between experiments and model prediction is very good. The effect of various parameters such as initial temperature, initial radius of the kernel, and the radiation energy loss have been investigated and it has been concluded that initial condition is very important on formation and expansion of the kernel.
Thermodynamic Modeling of Arsenic in Copper Smelting Processes
Chen, Chunlin; Zhang, Ling; Jahanshahi, Sharif
2010-12-01
Published data on the activity coefficients of arsenic in liquid copper, matte and, slag have been reviewed, assessed, and used in the development of thermodynamic databases for solution models of melts. The databases were validated against the literature data on the equilibrium distribution of arsenic between the matte and the slag. The models and databases were used in investigating the effects of matte grade, slag chemistry, SO2 partial pressure, arsenic loading, and temperature on the equilibrium distribution of arsenic between the melts and gas phase during copper smelting and converting. The results obtained show that the continuous smelting processes operates close to equilibrium between condensed phases with most arsenic reporting to the gas phase. A comparison of the batch and continuous converting processes showed a considerable difference with respect to the elimination of the arsenic from condensed phases. These results indicate batch processes to be more efficient in the removal of arsenic through the gas stream.
Modeling Tool Advances Rotorcraft Design
2007-01-01
Continuum Dynamics Inc. (CDI), founded in 1979, specializes in advanced engineering services, including fluid dynamic modeling and analysis for aeronautics research. The company has completed a number of SBIR research projects with NASA, including early rotorcraft work done through Langley Research Center, but more recently, out of Ames Research Center. NASA Small Business Innovation Research (SBIR) grants on helicopter wake modeling resulted in the Comprehensive Hierarchical Aeromechanics Rotorcraft Model (CHARM), a tool for studying helicopter and tiltrotor unsteady free wake modeling, including distributed and integrated loads, and performance prediction. Application of the software code in a blade redesign program for Carson Helicopters, of Perkasie, Pennsylvania, increased the payload and cruise speeds of its S-61 helicopter. Follow-on development resulted in a $24 million revenue increase for Sikorsky Aircraft Corporation, of Stratford, Connecticut, as part of the company's rotor design efforts. Now under continuous development for more than 25 years, CHARM models the complete aerodynamics and dynamics of rotorcraft in general flight conditions. CHARM has been used to model a broad spectrum of rotorcraft attributes, including performance, blade loading, blade-vortex interaction noise, air flow fields, and hub loads. The highly accurate software is currently in use by all major rotorcraft manufacturers, NASA, the U.S. Army, and the U.S. Navy.
Systematic assignment of thermodynamic constraints in metabolic network models
Kümmel, Anne; Panke, Sven; Heinemann, Matthias
2006-01-01
Background: The availability of genome sequences for many organisms enabled the reconstruction of several genome-scale metabolic network models. Currently, significant efforts are put into the automated reconstruction of such models. For this, several computational tools have been developed that par
Fundamental Thermodynamic Model for Analysis of Stream Temperature Data
Davis, L.; Reiter, M.; Groom, J.; Dent, L.
2012-12-01
Stream temperature is a critical aquatic ecosystem parameter and has been extensively studied for many years. Complex models have been built as a way to understand stream temperature dynamics and estimate the magnitude of anthropogenic influences on temperature. These models have proven very useful in estimating the relative contribution of various thermal energy sources to the stream heat budget and how management can alter the heat budget. However, the large number of measured or estimated input parameters required by such models makes their application to the analysis of specific stream temperature data difficult when the necessary input data is not readily available. To gain insight into the physical processes governing stream temperature behavior in forested streams we analyzed data based on fundamental thermodynamic concepts. The dataset we used is from a recent multi-year study on the effects of timber harvest on stream temperature in the Oregon Coast Range. From the hourly temperature data we extracted time-averaged diurnal heating and cooling rates. Examining the data in this context allowed us to qualitatively assess changes in the relative magnitude of stream temperature (T), stream equilibrium temperature (Teq), and effective heat transfer coefficient (h) across years and treatments. A benefit of analyzing the data in this way is that it separates the influence of timber harvest on stream temperature from that of climate variation. To categorize longitudinal temperature behaviors before and after timber harvest we developed a data-event matrix which specifies qualitative constraints (i.e., what is physically possible for T, Teq and h) for a given set of observed stream temperature responses. We then analyzed data from 18 different streams to categorize the temperature response to management. Understanding stream temperature dynamics using fundamental thermodynamic concepts provides insight into the processes governing stream temperature and the pathways
Thermodynamics of bread baking: A two-state model
Zürcher, Ulrich
2014-03-01
Bread baking can be viewed as a complex physico-chemical process. It is governed by transport of heat and is accompanied by changes such as gelation of starch, the expansion of air cells within dough, and others. We focus on the thermodynamics of baking and investigate the heat flow through dough and find that the evaporation of excess water in dough is the rate-limiting step. We consider a simplified one-dimensional model of bread, treating the excess water content as a two-state variable that is zero for baked bread and a fixed constant for unbaked dough. We arrive at a system of coupled, nonlinear ordinary differential equations, which are solved using a standard Runge-Kutta integration method. The calculated baking times are consistent with common baking experience.
Thermodynamic model of coherent island formation on vicinal substrate
Energy Technology Data Exchange (ETDEWEB)
Zhang, Xu, E-mail: zhangxubetter@gmail.com; Sun, Xiao-Hong [Henan Key Laboratory of Laser and Opto-electric Information Technology, School of Information Engineering, Zhengzhou University, Zhengzhou 450052 (China); Yu, Yanguang [School of Electrical, Computer and Telecommunications Engineering, University of Wollongong, Northfields Ave, Wollongong, New South Wales 2522 (Australia); Ren, Xiaomin [State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876 (China)
2014-04-28
A thermodynamic model has been proposed to address the formation of coherent island on the vicinal substrate. The morphological transition from square based island to elongated based one with various substrate misorientations is described. The initial stage of nucleation and growth process of islands in Stranski–Krastanow system is studied by taking into account the elastic deformations and the change of energy in the case of two-dimensional growth mode. The theoretical analysis shows the minimum nucleation barrier of island is on the decrease with increment of substrate misorientation, which means the nucleation of island on vicinal substrate is more favorable than that on flat substrate. By using the fitting data of experimental results done by Persichetti et al., [Phys. Rev. Lett. 104, 036104 (2010) and Phys. Rev. B 82, 121309(R) (2010)], we provide a meaningful explanation of the experimental observations.
Coal pyrolysis in plasma and thermodynamic analysis for model compound
Energy Technology Data Exchange (ETDEWEB)
Lu, Y.; Pang, X.; Bao, W.; Xie, K. [Shanxi Key Laboratory of Coal Science and Technology, Taiyuan (China)
2001-02-01
On the basis of study on coal and graphite pyrolysis in hydrogen-enriched argon plasma jet reactor, thermodynamic analysis for reactions producing acetylene was carried out by the means of selecting model compounds including various gaseous aliphatic and liquid aromatic hydrocarbons, which were regarded as similar to the primary volatile of coal, and by calculating the changes of Gibbs functions under deferent temperatures. The fact that the reactions of the volatiles releasing from coal play an essential part in acetylene formation from coal in H{sub 2}-Ar plasma was verified. The result that acetylene can be produced easily in high temperature can be deduced from entropy effects by theoretical analysis and experiment. These results are of significance for mechanism investigation of acetylene formation in plasma reactor. 7 refs., 1 fig., 3 tabs.
Numerical model study of radio frequency vessel sealing thermodynamics
Pearce, John
2015-03-01
Several clinically successful clinical radio frequency vessel-sealing devices are currently available. The dominant thermodynamic principles at work involve tissue water vaporization processes. It is necessary to thermally denature vessel collagen, elastin and their adherent proteins to achieve a successful fusion. Collagens denature at middle temperatures, between about 60 and 90 C depending on heating time and rate. Elastin, and its adherent proteins, are more thermally robust, and require temperatures in excess of the boiling point of water at atmospheric pressure to thermally fuse. Rapid boiling at low apposition pressures leads to steam vacuole formation, brittle tissue remnants and frequently to substantial disruption in the vessel wall, particularly in high elastin-content arteries. High apposition pressures substantially increase the equilibrium boiling point of tissue water and are necessary to ensure a high probability of a successful seal. The FDM numerical models illustrate the beneficial effects of high apposition pressures.
Thermodynamic modeling of the Ba - Mg binary system
Energy Technology Data Exchange (ETDEWEB)
Ren, Xin; Li, Changrong; Du, Zhenmin; Guo, Cuiping; Chen, Sicheng [Univ. of Science and Technology, Beijing (China). School of Materials Science and Engineering
2013-04-15
On the basis of the thermochemical and phase equilibrium experimental data, the phase diagram of the Ba - Mg binary system has been assessed by means of the calculation of phase diagrams technique. The liquid phase is of unlimited solubility and modeled as a solution phase using the Redlich-Kister equation. The intermetallic compounds, Mg{sub 17}Ba{sub 2}, Mg{sub 23}Ba{sub 6} and Mg{sub 2}Ba, with no solubility ranges are treated as strict stoichiometric compounds with the formula Mg{sub m} Ba{sub n}. Two terminal phases, BccBa and HcpMg, are kept as solution phases, since the solubilities of the two phases are of considerable importance. After optimization, a set of self-consistent thermodynamic parameters has been obtained. The calculated values agree well with the available experimental data.
Thermodynamic study on some alkanediol solutions: Measurement and modeling
Energy Technology Data Exchange (ETDEWEB)
Moosavi, Mehrdad; Motahari, Ahmad; Omrani, Abdollah, E-mail: omrani@umz.ac.ir; Rostami, Abbas Ali
2013-06-10
Highlights: • Measuring densities and viscosities for binary mixtures of some alkanediols. • Finding excess molar volume, partial molar volume and thermal expansion coefficient. • Fitting excess molar volume values with PFP and Redlich–Kister polynomial equations. • Deducing excess Gibbs free energy of activation and other thermodynamic parameters. • Predicting viscosity values with different single parameter semi empirical equations. - Abstract: The densities ρ and viscosities η of 1,2-ethanediol with 1,2-propanediol or 1,3-propanediol, and 1,2-propanediol with 1,3-propanediol binary liquid mixtures over the entire concentration range at temperatures (298.15 to 308.15) K with 5 K interval were measured. The experimental data were used to calculate the excess molar volume V{sub m}{sup E}, partial molar volume V{sup ¯}{sub m,i}, partial molar volume at infinite dilution V{sup ¯}{sub i}{sup ∞}, apparent molar volume V{sub φi}, coefficient of thermal expansion α{sub p}, excess coefficient of thermal expansion α{sub p}{sup E}, excess viscosity η{sup E}, excess Gibbs energy of activation ΔG{sup *E}, and other thermodynamic parameters. A Redlich–Kister equation and Prigogine–Flory–Patterson (PFP) model was applied to correlate the excess molar volume results. Moreover, the viscosity data were correlated with the Grunberg–Nissan, Tamura–Kurata, Hind–Ubbelohde and Katti–Chaudhary equations. Good agreement was found between experimental data and modeling results.
Dark Energy Models and Laws of Thermodynamics in Bianchi I Model
Sharif, M
2013-01-01
This paper is devoted to check validity of the laws of thermodynamics for LRS Bianchi type I universe model which is filled with combination of dark matter and dark energy. We take two types of dark energy models, i.e., generalized holographic dark energy and generalized Ricci dark energy. It is proved that the first and generalized second law of thermodynamics are valid on the apparent horizon for both the models. Further, we take fixed radius $L$ of the apparent horizon with original holographic or Ricci dark energy. We conclude that the first and generalized second laws of thermodynamics do not hold on the horizon of fixed radius $L$ for both the models.
Energy Technology Data Exchange (ETDEWEB)
Caro, J A
2007-07-31
This research has two main objectives: (1) The development of computational tools to evaluate alloy properties, using the information contained in thermodynamic functions. We aim at improving the ability of classical potentials to account for complex alloy behavior; and (2) The application of these tools to predict properties of alloys under irradiation. Atomistic simulations of alloys at the empirical level face the challenge of correctly modeling basic thermodynamic properties. In the periods reported previously we develop a methodology to generalize many-body classic potentials to incorporate complex formation energy curves. Application to Fe-Cr allows us to predict the implications of the ab initio results of formation energy on the phase diagram of this alloy and to get a detailed insight into the processes leading to precipitation of {alpha}{prime} phase under irradiation. In particular in this period we report on the consequences of the negative heat of formation at low Cr composition on the short range order SRO existing in the {alpha} phase. We elaborate a simple description of SRO on a two phase alloy and compare the predictions with experiments. We provide a key to rationalize a diversity of experiments on SRO versus annealing time or irradiation dose.
Jacobs, M. H.; Van Den Berg, A. P.
2013-12-01
Thermodynamic databases are indispensable tools in materials science and mineral physics to derive thermodynamic properties in regions of pressure-temperature-composition space for which experimental data are not available or scant. Because the amount of phases and substances in a database is arbitrarily large, thermodynamic formalisms coupled to these databases are often kept as simple as possible to sustain computational efficiency. Although formalisms based on parameterizations of 1 bar thermodynamic data, commonly used in Calphad methodology, meet this requirement, physically unrealistic behavior in properties hamper the application in the pressure regime prevailing in the Earth's lower mantle. The application becomes especially cumbersome when they are applied to planetary mantles of massive super earth exoplanets or in the development of pressure scales, where Hugoniot data at extreme conditions are involved. Methods based on the Mie-Grüneisen-Debye formalism have the advantage that physically unrealistic behavior in thermodynamic properties is absent, but due to the simple construction of the vibrational density of states (VDoS), they lack engineering precision in the low-pressure regime, especially at 1 bar pressure, hampering application of databases incorporating such formalism to industrial processes. To obtain a method that is generally applicable in the complete stability range of a material, we developed a method based on an alternative use of Kieffer's lattice vibrational formalism. The method requires experimental data to constrain the model parameters and is therefore semi-empirical. It has the advantage that microscopic properties for substances, such as the VDoS, Grüneisen parameters and electronic and static lattice properties resulting from present-day ab-initio methods can be incorporated to constrain a thermodynamic analysis of experimental data. It produces results free from physically unrealistic behavior at high pressure and temperature
T-MATS Toolbox for the Modeling and Analysis of Thermodynamic Systems
Chapman, Jeffryes W.
2014-01-01
The Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS) is a MATLABSimulink (The MathWorks Inc.) plug-in for creating and simulating thermodynamic systems and controls. The package contains generic parameterized components that can be combined with a variable input iterative solver and optimization algorithm to create complex system models, such as gas turbines.
A thermodynamic model of microtubule assembly and disassembly.
Directory of Open Access Journals (Sweden)
Bernard M A G Piette
Full Text Available Microtubules are self-assembling polymers whose dynamics are essential for the normal function of cellular processes including chromosome separation and cytokinesis. Therefore understanding what factors effect microtubule growth is fundamental to our understanding of the control of microtubule based processes. An important factor that determines the status of a microtubule, whether it is growing or shrinking, is the length of the GTP tubulin microtubule cap. Here, we derive a Monte Carlo model of the assembly and disassembly of microtubules. We use thermodynamic laws to reduce the number of parameters of our model and, in particular, we take into account the contribution of water to the entropy of the system. We fit all parameters of the model from published experimental data using the GTP tubulin dimer attachment rate and the lateral and longitudinal binding energies of GTP and GDP tubulin dimers at both ends. Also we calculate and incorporate the GTP hydrolysis rate. We have applied our model and can mimic published experimental data, which formerly suggested a single layer GTP tubulin dimer microtubule cap, to show that these data demonstrate that the GTP cap can fluctuate and can be several microns long.
A thermodynamic model of microtubule assembly and disassembly.
Piette, Bernard M A G; Liu, Junli; Peeters, Kasper; Smertenko, Andrei; Hawkins, Timothy; Deeks, Michael; Quinlan, Roy; Zakrzewski, Wojciech J; Hussey, Patrick J
2009-08-11
Microtubules are self-assembling polymers whose dynamics are essential for the normal function of cellular processes including chromosome separation and cytokinesis. Therefore understanding what factors effect microtubule growth is fundamental to our understanding of the control of microtubule based processes. An important factor that determines the status of a microtubule, whether it is growing or shrinking, is the length of the GTP tubulin microtubule cap. Here, we derive a Monte Carlo model of the assembly and disassembly of microtubules. We use thermodynamic laws to reduce the number of parameters of our model and, in particular, we take into account the contribution of water to the entropy of the system. We fit all parameters of the model from published experimental data using the GTP tubulin dimer attachment rate and the lateral and longitudinal binding energies of GTP and GDP tubulin dimers at both ends. Also we calculate and incorporate the GTP hydrolysis rate. We have applied our model and can mimic published experimental data, which formerly suggested a single layer GTP tubulin dimer microtubule cap, to show that these data demonstrate that the GTP cap can fluctuate and can be several microns long.
STREAM: Static Thermodynamic REgulAtory Model of transcription.
Bauer, Denis C; Bailey, Timothy L
2008-11-01
Understanding the transcriptional regulation of a gene in detail is a crucial step towards uncovering and ultimately utilizing the regulatory grammar of the genome. Modeling transcriptional regulation using thermodynamic equations has become an increasingly important approach towards this goal. Here, we present stream, the first publicly available framework for modeling, visualizing and predicting the regulation of the transcription rate of a target gene. Given the concentrations of a set of transcription factors (TFs), the TF binding sites (TFBSs) in a regulatory DNA region, and the transcription rate of the target gene, stream will optimize its parameters to generate a model that best fits the input data. This trained model can then be used to (a) validate that the given set of TFs is able to regulate the target gene and (b) to predict the transcription rate under different conditions (e.g. different tissues, knockout/additional TFs or mutated/missing TFBSs). The platform independent executable of stream, as well as a tutorial and the full documentation, are available at http://bioinformatics.org.au/stream/. stream requires Java version 5 or higher.
Tancret, F.
2013-06-01
A new alloy design procedure is proposed, combining in a single computational tool several modelling and predictive techniques that have already been used and assessed in the field of materials science and alloy design: a genetic algorithm is used to optimize the alloy composition for target properties and performance on the basis of the prediction of mechanical properties (estimated by Gaussian process regression of data on existing alloys) and of microstructural constitution, stability and processability (evaluated by computational themodynamics). These tools are integrated in a unique Matlab programme. An example is given in the case of the design of a new nickel-base superalloy for future power plant applications (such as the ultra-supercritical (USC) coal-fired plant, or the high-temperature gas-cooled nuclear reactor (HTGCR or HTGR), where the selection criteria include cost, oxidation and creep resistance around 750 °C, long-term stability at service temperature, forgeability, weldability, etc.
Critical, statistical, and thermodynamical properties of lattice models
Energy Technology Data Exchange (ETDEWEB)
Varma, Vipin Kerala
2013-10-15
In this thesis we investigate zero temperature and low temperature properties - critical, statistical and thermodynamical - of lattice models in the contexts of bosonic cold atom systems, magnetic materials, and non-interacting particles on various lattice geometries. We study quantum phase transitions in the Bose-Hubbard model with higher body interactions, as relevant for optical lattice experiments of strongly interacting bosons, in one and two dimensions; the universality of the Mott insulator to superfluid transition is found to remain unchanged for even large three body interaction strengths. A systematic renormalization procedure is formulated to fully re-sum these higher (three and four) body interactions into the two body terms. In the strongly repulsive limit, we analyse the zero and low temperature physics of interacting hard-core bosons on the kagome lattice at various fillings. Evidence for a disordered phase in the Ising limit of the model is presented; in the strong coupling limit, the transition between the valence bond solid and the superfluid is argued to be first order at the tip of the solid lobe.
Directory of Open Access Journals (Sweden)
Charles-Michel Marle
2016-10-01
Full Text Available I present in this paper some tools in symplectic and Poisson geometry in view of their applications in geometric mechanics and mathematical physics. After a short discussion of the Lagrangian an Hamiltonian formalisms, including the use of symmetry groups, and a presentation of the Tulczyjew’s isomorphisms (which explain some aspects of the relations between these formalisms, I explain the concept of manifold of motions of a mechanical system and its use, due to J.-M. Souriau, in statistical mechanics and thermodynamics. The generalization of the notion of thermodynamic equilibrium in which the one-dimensional group of time translations is replaced by a multi-dimensional, maybe non-commutative Lie group, is fully discussed and examples of applications in physics are given.
DEFF Research Database (Denmark)
Sadegh, Negar; Stenby, Erling Halfdan; Thomsen, Kaj
2015-01-01
Aqueous MDEA is the most commonly used solvent for H2S removal from natural gas. A reliable thermodynamic model is required for the proper design of natural gas sweetening processes. In this study, a rigorous thermodynamic model is developed to represent properties of the H2S-MDEA-H2O ternary......-180°C, H2S partial pressure of 0.0033-8329.71kPa, MDEA mass% of 0-50 and loading range of 0-2.17....
Alien wavelength modeling tool and field trial
DEFF Research Database (Denmark)
Sambo, N.; Sgambelluri, A.; Secondini, M.
2015-01-01
A modeling tool is presented for pre-FEC BER estimation of PM-QPSK alien wavelength signals. A field trial is demonstrated and used as validation of the tool's correctness. A very close correspondence between the performance of the field trial and the one predicted by the modeling tool has been...
Gladkov, Svyatoslav; Kochmann, Julian; Reese, Stefanie; Hütter, Markus; Svendsen, Bob
2016-04-01
The purpose of the current work is the comparison of thermodynamic model formulations for chemically and structurally inhomogeneous solids at finite deformation based on "standard" non-equilibrium thermodynamics [SNET: e. g. S. de Groot and P. Mazur, Non-equilibrium Thermodynamics, North Holland, 1962] and the general equation for non-equilibrium reversible-irreversible coupling (GENERIC) [H. C. Öttinger, Beyond Equilibrium Thermodynamics, Wiley Interscience, 2005]. In the process, non-isothermal generalizations of standard isothermal conservative [e. g. J. W. Cahn and J. E. Hilliard, Free energy of a non-uniform system. I. Interfacial energy. J. Chem. Phys. 28 (1958), 258-267] and non-conservative [e. g. S. M. Allen and J. W. Cahn, A macroscopic theory for antiphase boundary motion and its application to antiphase domain coarsening. Acta Metall. 27 (1979), 1085-1095; A. G. Khachaturyan, Theory of Structural Transformations in Solids, Wiley, New York, 1983] diffuse interface or "phase-field" models [e. g. P. C. Hohenberg and B. I. Halperin, Theory of dynamic critical phenomena, Rev. Modern Phys. 49 (1977), 435-479; N. Provatas and K. Elder, Phase Field Methods in Material Science and Engineering, Wiley-VCH, 2010.] for solids are obtained. The current treatment is consistent with, and includes, previous works [e. g. O. Penrose and P. C. Fife, Thermodynamically consistent models of phase-field type for the kinetics of phase transitions, Phys. D 43 (1990), 44-62; O. Penrose and P. C. Fife, On the relation between the standard phase-field model and a "thermodynamically consistent" phase-field model. Phys. D 69 (1993), 107-113] on non-isothermal systems as a special case. In the context of no-flux boundary conditions, the SNET- and GENERIC-based approaches are shown to be completely consistent with each other and result in equivalent temperature evolution relations.
Chemical thermodynamics as a predictive tool in the reactive metal brazing of ceramics
Energy Technology Data Exchange (ETDEWEB)
Wang, G. [Edison Welding Inst., Columbus, OH (United States); Lannutti, J.J. [Ohio State Univ., Columbus, OH (United States)
1995-06-01
Thermodynamics have long been applied to the understanding of the reactive wetting phenomena in metal-ceramic joining. The authors postulate the existence of a ``solvent effect`` due to the interaction between the reactive element addition and the brazing alloy. This effect plays a significant role in reactive wetting. By taking this effect into account, more realistic reactivities of different reactive element additions into a given brazing base alloy are predicted. Irreversible thermodynamics are also used to characterize the driving forces for reactive metal-ceramic joining.
Chemical thermodynamics as a predictive tool in the reactive metal brazing of ceramics
Wang, G.; Lannutti, J. J.
1995-06-01
Thermodynamics have long been applied to our understanding of the reactive wetting phenomena in metal-ceramic joining. We postulate the existence of a “solvent effect” due to the interaction between the reactive element addition and the brazing alloy. This effect plays a significant role in reactive wetting. By taking this effect into account, more realistic reactivities of different reactive element additions into a given brazing base alloy are predicted. Irreversible thermodynamics are also used to characterize the driving forces for reactive metal-ceramic joining.
THERMODYNAMIC AND KINETIC MODELING OF ADVANCED NUCLEAR FUELS - FINAL LDRD-ER REPORT
Energy Technology Data Exchange (ETDEWEB)
Turchi, P
2011-11-28
This project enhanced our theoretical capabilities geared towards establishing the basic science of a high-throughput protocol for the development of advanced nuclear fuel that should couple modern computational materials modeling and simulation tools, fabrication and characterization capabilities, and targeted high throughput performance testing experiments. The successful conclusion of this ER project allowed us to upgrade state-of-the-art modeling codes, and apply these modeling tools to ab initio energetics and thermodynamic assessments of phase diagrams of various mixtures of actinide alloys, propose a tool for optimizing composition of complex alloys for specific properties, predict diffusion behavior in diffusion couples made of actinide and transition metals, include one new equation in the LLNL phase-field AMPE code, and predict microstructure evolution during alloy coring. In FY11, despite limited funding, the team also initiated an experimental activity, with collaboration from Texas A&M University by preparing samples of nuclear fuels in bulk forms and for diffusion couple studies and metallic matrices, and performing preliminary characterization.
Comparison of thermodynamic properties of coarse-grained and atomic-level simulation models.
Baron, Riccardo; Trzesniak, Daniel; de Vries, Alex H; Elsener, Andreas; Marrink, Siewert J; van Gunsteren, Wilfred F
2007-02-19
Thermodynamic data are often used to calibrate or test amomic-level (AL) force fields for molecular dynamics (MD) simulations. In contrast, the majority of coarse-grained (CG) force fields do not rely extensively on thermodynamic quantities. Recently, a CG force field for lipids, hydrocarbons, ions, and water, in which approximately four non-hydrogen atoms are mapped onto one interaction site, has been proposed and applied to study various aspects of lipid systems. To date, no extensive investigation of its capability to describe salvation thermodynamics has been undertaken. In the present study, a detailed picture of vaporization, solvation, and phase-partitioning thermodynamics for liquid hydrocarbons and water was obtained at CG and AL resolutions, in order to compare the two types or models and evaluate their ability to describe thermodynamic properties in the temperature range between 263 and 343 K. Both CG and AL models capture the experimental dependence of the thermodynamic properties on the temperature, albeit a systematically weaker dependence is found for the CG model. Moreover, deviations are found for solvation thermodynamics and for the corresponding enthalpy-entropy compensation for the CG model. Particularly water/oil repulsion seems to be overestimated. However, the results suggest that the thermodynamic properties considered should be reproducible by a CG model provided it is reparametrized on the basis of these liquid-phase properties.
Incorporating nucleosomes into thermodynamic models of transcription regulation.
Raveh-Sadka, Tali; Levo, Michal; Segal, Eran
2009-08-01
Transcriptional control is central to many cellular processes, and, consequently, much effort has been devoted to understanding its underlying mechanisms. The organization of nucleosomes along promoter regions is important for this process, since most transcription factors cannot bind nucleosomal sequences and thus compete with nucleosomes for DNA access. This competition is governed by the relative concentrations of nucleosomes and transcription factors and by their respective sequence binding preferences. However, despite its importance, a mechanistic understanding of the quantitative effects that the competition between nucleosomes and factors has on transcription is still missing. Here we use a thermodynamic framework based on fundamental principles of statistical mechanics to explore theoretically the effect that different nucleosome organizations along promoters have on the activation dynamics of promoters in response to varying concentrations of the regulating factors. We show that even simple landscapes of nucleosome organization reproduce experimental results regarding the effect of nucleosomes as general repressors and as generators of obligate binding cooperativity between factors. Our modeling framework also allows us to characterize the effects that various sequence elements of promoters have on the induction threshold and on the shape of the promoter activation curves. Finally, we show that using only sequence preferences for nucleosomes and transcription factors, our model can also predict expression behavior of real promoter sequences, thereby underscoring the importance of the interplay between nucleosomes and factors in determining expression kinetics.
Thermodynamic Property Model of Wide-Fluid Phase Propane
Directory of Open Access Journals (Sweden)
I Made Astina
2007-05-01
Full Text Available A new thermodynamic property model for propane is expressed in form of the Helmholtz free energy function. It consists of eight terms of the ideal-gas part and eighteen terms of the residual part. Accurate experimental data of fluid properties and theoretical approach from the intermolecular potential were simultaneously considered in the development to insure accuracy and to improve reliability of the equation of state over wide range of pressures and temperatures. Based on the state range of experimental data used in the model development, the validity range is judged from the triple-point of 85.48 K to temperature of 450 K and pressure up to 60 MPa. The uncertainties with respect to different properties are estimated to be 0.03% in ideal-gas isobaric specific heat, 0.2% in liquid phase density, 0.3% in gaseous phase density 1% in specific heats, 0.1% in vapor-pressure except at very low temperatures, 0.05% in saturated-liquid density, 0.02% in speed of sound of the gaseous phase and 1% in speed of sound of the liquid phase.
Thermodynamic model of heterochromatin formation through epigenetic regulation
Mulligan, Peter J.; Koslover, Elena F.; Spakowitz, Andrew J.
2015-02-01
Gene regulation in eukaryotes requires the segregation of silenced genomic regions into densely packed heterochromatin, leaving the active genes in euchromatin regions more accessible. We introduce a model that connects the presence of epigenetically inherited histone marks, methylation at histone 3 lysine-9, to the physical compaction of chromatin fibers via the binding of heterochromatin protein 1 (HP1). Our model demonstrates some of the key physical features that are necessary to explain experimental observations. In particular, we demonstrate that strong cooperative interactions among the HP1 proteins are necessary to see the phase segregation of heterochromatin and euchromatin regions. We also explore how the cell can use the concentration of HP1 to control condensation and under what circumstances there is a threshold of methylation over which the fibers will compact. Finally, we consider how different potential in vivo fiber structures as well as the flexibility of the histone 3 tail can affect the bridging of HP1. Many of the observations that we make about the HP1 system are guided by general thermodynamics principles and thus could play a role in other DNA organizational processes such as the binding of linker histones.
A Thermodynamically-consistent FBA-based Approach to Biogeochemical Reaction Modeling
Shapiro, B.; Jin, Q.
2015-12-01
Microbial rates are critical to understanding biogeochemical processes in natural environments. Recently, flux balance analysis (FBA) has been applied to predict microbial rates in aquifers and other settings. FBA is a genome-scale constraint-based modeling approach that computes metabolic rates and other phenotypes of microorganisms. This approach requires a prior knowledge of substrate uptake rates, which is not available for most natural microbes. Here we propose to constrain substrate uptake rates on the basis of microbial kinetics. Specifically, we calculate rates of respiration (and fermentation) using a revised Monod equation; this equation accounts for both the kinetics and thermodynamics of microbial catabolism. Substrate uptake rates are then computed from the rates of respiration, and applied to FBA to predict rates of microbial growth. We implemented this method by linking two software tools, PHREEQC and COBRA Toolbox. We applied this method to acetotrophic methanogenesis by Methanosarcina barkeri, and compared the simulation results to previous laboratory observations. The new method constrains acetate uptake by accounting for the kinetics and thermodynamics of methanogenesis, and predicted well the observations of previous experiments. In comparison, traditional methods of dynamic-FBA constrain acetate uptake on the basis of enzyme kinetics, and failed to reproduce the experimental results. These results show that microbial rate laws may provide a better constraint than enzyme kinetics for applying FBA to biogeochemical reaction modeling.
Nathoo, Jeeten; Randall, Dyllon Garth
2016-01-01
Membrane distillation (MD) could be applicable in zero liquid discharge applications. This is due to the fact that MD is applicable at high salinity ranges which are generally outside the scope of reverse osmosis (RO) applications, although this requires proper management of precipitating salts to avoid membrane fouling. One way of managing these salts is with MD crystallisation (MDC). This paper focuses on the applicability of MDC for the treatment of mining wastewater by thermodynamically modelling the aqueous chemistry of the process at different temperatures. The paper is based on the typical brine generated from an RO process in the South African coal mining industry and investigates the effect water recovery and operating temperature have on the salts that are predicted to crystallise out, the sequence in which they will crystallise out and purities as a function of the water recovery. The study confirmed the efficacy of using thermodynamic modelling as a tool for investigating and predicting the crystallisation aspects of the MDC process. The key finding from this work was that, for an MDC process, a purer product can be obtained at higher operating temperatures and recoveries because of the inverse solubility of calcium sulphate.
The Laboratory as a Tool for Learning Thermodynamics, Heat Transfer, and Thermal Systems.
Neto, Alberto Hernandez; Tribess, Arlindo; Fiorelli, Flavio Augusto Sanzogo
The consolidation of the theoretical concepts as well as the use and learning of experimental techniques that are compatible with the technological evolution has been the main goals in Thermodynamics and Heat Transfer and Thermal Systems Laboratories at Escola Politecnica of University of Sao Paulo. The infra-structure and experimental benches in…
DEFF Research Database (Denmark)
Fontenete, Sílvia; Guimarães, Nuno; Wengel, Jesper
2016-01-01
Abstract The thermodynamics and kinetics of DNA hybridization, i.e. the process of self-assembly of one, two or more complementary nucleic acid strands, has been studied for many years. The appearance of the nearest-neighbor model led to several theoretical and experimental papers on DNA thermody......Abstract The thermodynamics and kinetics of DNA hybridization, i.e. the process of self-assembly of one, two or more complementary nucleic acid strands, has been studied for many years. The appearance of the nearest-neighbor model led to several theoretical and experimental papers on DNA...... thermodynamics that provide reasonably accurate thermodynamic information on nucleic acid duplexes and allow estimation of the melting temperature. Because there are no thermodynamic models specifically developed to predict the hybridization temperature of a probe used in a fluorescence in situ hybridization...
Thermodynamic Modeling of the YO(l.5)-ZrO2 System
Jacobson, Nathan S.; Liu, Zi-Kui; Kaufman, Larry; Zhang, Fan
2003-01-01
The YO1.5-ZrO2 system consists of five solid solutions, one liquid solution, and one intermediate compound. A thermodynamic description of this system is developed, which allows calculation of the phase diagram and thermodynamic properties. Two different solution models are used-a neutral species model with YO1.5 and ZrO2 as the components and a charged species model with Y(+3), Zr(+4), O(-2), and vacancies as components. For each model, regular and sub-regular solution parameters are derived fiom selected equilibrium phase and thermodynamic data.
Thermodynamic Modeling of the YO(l.5)-ZrO2 System
Jacobson, Nathan S.; Liu, Zi-Kui; Kaufman, Larry; Zhang, Fan
2003-01-01
The YO1.5-ZrO2 system consists of five solid solutions, one liquid solution, and one intermediate compound. A thermodynamic description of this system is developed, which allows calculation of the phase diagram and thermodynamic properties. Two different solution models are used-a neutral species model with YO1.5 and ZrO2 as the components and a charged species model with Y(+3), Zr(+4), O(-2), and vacancies as components. For each model, regular and sub-regular solution parameters are derived fiom selected equilibrium phase and thermodynamic data.
Performability Modelling Tools, Evaluation Techniques and Applications
Haverkort, Boudewijn R.H.M.
1990-01-01
This thesis deals with three aspects of quantitative evaluation of fault-tolerant and distributed computer and communication systems: performability evaluation techniques, performability modelling tools, and performability modelling applications. Performability modelling is a relatively new
Coupled thermodynamic-dynamic semi-analytical model of Free Piston Stirling engines
Formosa, Fabien
2013-01-01
The study of free piston Stirling engine (FPSE) requires both accurate thermodynamic and dynamic modelling to predict its performances. The steady state behaviour of the engine partly relies on non linear dissipative phenomena such as pressure drop loss within heat exchangers which is dependant on the temperature within the associated components. An analytical thermodynamic model which encompasses the effectiveness and the flaws of the heat exchangers and the regenerator has been previously developed and validated. A semi-analytical dynamic model of FPSE is developed and presented in this paper. The thermodynamic model is used to define the thermal variables that are used in the dynamic model which evaluates the kinematic results. Thus, a coupled iterative strategy has been used to perform a global simulation. The global modelling approach has been validated using the experimental data available from the NASA RE-1000 Stirling engine prototype. The resulting coupled thermodynamic-dynamic model using a standard...
Thermodynamic model of Mars Oxygen ISRU Experiment (MOXIE)
Meyen, Forrest E.; Hecht, Michael H.; Hoffman, Jeffrey A.
2016-12-01
As humankind expands its footprint in the solar system, it is increasingly important to make use of the resources already in our solar system to make these missions economically feasible and sustainable. In-Situ Resource Utilization (ISRU), the science of using resources at a destination to support exploration missions, unlocks potential destinations by significantly reducing the amount of resources that need to be launched from Earth. Carbon dioxide is an example of an in-situ resource that comprises 96% of the Martian atmosphere and can be used as a source of oxygen for propellant and life support systems. The Mars Oxygen ISRU Experiment (MOXIE) is a payload being developed for NASA's upcoming Mars 2020 rover. MOXIE will produce oxygen from the Martian atmosphere using solid oxide electrolysis (SOXE). MOXIE is on the order of magnitude of a 1% scale model of an oxygen processing plant that might enable a human expedition to Mars in the 2030s through the production of the oxygen needed for the propellant of a Mars ascent vehicle. MOXIE is essentially an energy conversion system that draws energy from the Mars 2020 rover's radioisotope thermoelectric generator and ultimately converts it to stored energy in oxygen and carbon monoxide molecules. A thermodynamic model of this novel system is used to understand this process in order to derive operating parameters for the experiment. This paper specifically describes the model of the SOXE component. Assumptions and idealizations are addressed, including 1D and 2D simplifications. Operating points are discussed as well as impacts of flow rates and production.
Energy Technology Data Exchange (ETDEWEB)
Li, Yulan; Hu, Shenyang Y.; Sun, Xin; Khaleel, Mohammad A.
2011-06-15
Microstructure evolution kinetics in irradiated materials has strongly spatial correlation. For example, void and second phases prefer to nucleate and grow at pre-existing defects such as dislocations, grain boundaries, and cracks. Inhomogeneous microstructure evolution results in inhomogeneity of microstructure and thermo-mechanical properties. Therefore, the simulation capability for predicting three dimensional (3-D) microstructure evolution kinetics and its subsequent impact on material properties and performance is crucial for scientific design of advanced nuclear materials and optimal operation conditions in order to reduce uncertainty in operational and safety margins. Very recently the meso-scale phase-field (PF) method has been used to predict gas bubble evolution, void swelling, void lattice formation and void migration in irradiated materials,. Although most results of phase-field simulations are qualitative due to the lake of accurate thermodynamic and kinetic properties of defects, possible missing of important kinetic properties and processes, and the capability of current codes and computers for large time and length scale modeling, the simulations demonstrate that PF method is a promising simulation tool for predicting 3-D heterogeneous microstructure and property evolution, and providing microstructure evolution kinetics for higher scale level simulations of microstructure and property evolution such as mean field methods. This report consists of two parts. In part I, we will present a new phase-field model for predicting interstitial loop growth kinetics in irradiated materials. The effect of defect (vacancy/interstitial) generation, diffusion and recombination, sink strength, long-range elastic interaction, inhomogeneous and anisotropic mobility on microstructure evolution kinetics is taken into account in the model. The model is used to study the effect of elastic interaction on interstitial loop growth kinetics, the interstitial flux, and sink
Fire behavior modeling-a decision tool
Jack Cohen; Bill Bradshaw
1986-01-01
The usefulness of an analytical model as a fire management decision tool is determined by the correspondence of its descriptive capability to the specific decision context. Fire managers must determine the usefulness of fire models as a decision tool when applied to varied situations. Because the wildland fire phenomenon is complex, analytical fire spread models will...
Spatial Modeling Tools for Cell Biology
2006-10-01
34 iv Figure 5.1: Computational results for a diffusion problem on planar square thin film............ 36 Figure 5.2... Wisc . Open Microscopy Env. Pre-CoBi Model Lib. CFDRC CoBi Tools CFDRC CoBi Tools Simulation Environment JigCell Tools Figure 4.1: Cell biology
Donnet, Marcel; Bowen, Paul; Lemaître, Jacques
2009-12-15
Thermodynamic solubility calculations are normally only related to thermodynamic equilibria in solution. In this paper, we extend the use of such solubility calculations to help elucidate possible precipitation reaction pathways during the entire reaction. We also estimate the interfacial energy of particles using only solubility data by a modification of Mersmann's approach. We have carried this out by considering precipitation reactions as a succession of small quasi-equilibrium states. Thus possible equilibrium precipitation pathways can be evaluated by calculating the evolution of surface charge, particle size and/or interfacial energy during the ongoing reaction. The approach includes the use of the Kelvin's law to express the influence of particle size on the solubility constant of precipitates, the use of Nernst's law to calculate surface potentials from solubility calculations and relate this to experimentally measured zeta potentials. Calcium carbonate precipitation and zeta potential measurements of well characterised high purity calcite have been used as a model system to validate the calculated values. The clarification of the change in zeta potential on titration illustrates the power of this approach as a tool for reaction pathway prediction and hence knowledge based tailoring of precipitation reactions.
Thermodynamic modelling of Mg(BH{sub 4}){sub 2}
Energy Technology Data Exchange (ETDEWEB)
Pinatel, E.R.; Albanese, E.; Civalleri, B.; Baricco, M.
2015-10-05
Highlights: • DFT calculations providing missing thermodynamic data for Mg(BH{sub 4}){sub 2}were performed. • A Calphad assessment of Mg(BH{sub 4}){sub 2} was performed, considering all the available data. • Stable and metastable phase diagrams have been calculated for Mg(BH{sub 4}){sub 2}. • Several dehydrogenation paths of Mg(BH{sub 4}){sub 2} have been analysed and discussed. - Abstract: Application of the Calphad method to the description of thermodynamic properties in complex borohydride-based systems may allow a faster development of hydrogen storage materials. It is, however, limited by the low number of available thermodynamic description for borohydrides in thermodynamic databases. In the present work, a Calphad assessment of Mg(BH{sub 4}){sub 2} has been performed, considering available thermodynamic data. DFT calculations have been performed in order to provide missing thermodynamic data and to calculate the relative stability of the α, β and γ polymorphs. Experimental results have been compared detecting inconsistencies between them. The database obtained has been used to estimate driving forces for several dehydrogenation reactions. The dehydrogenation reaction leading to the formation of MgB{sub 2} and gaseous hydrogen is the most favoured thermodynamically, even if at low temperatures the formation of MgB{sub 12}H{sub 12} is competitive. On the contrary, positive driving forces have been calculated for the decomposition into B{sub 2}H{sub 6} and Mg(B{sub 3}H{sub 8}){sub 2}.
On Thermodynamics Problems in the Single-Phase-Lagging Heat Conduction Model
Directory of Open Access Journals (Sweden)
Shu-Nan Li
2016-11-01
Full Text Available Thermodynamics problems for the single-phase-lagging (SPL model have not been much studied. In this paper, the violation of the second law of thermodynamics by the SPL model is studied from two perspectives, which are the negative entropy production rate and breaking equilibrium spontaneously. The methods for the SPL model to avoid the negative entropy production rate are proposed, which are extended irreversible thermodynamics and the thermal relaxation time. Modifying the entropy production rate positive or zero is not enough to avoid the violation of the second law of thermodynamics for the SPL model, because the SPL model could cause breaking equilibrium spontaneously in some special circumstances. As comparison, it is shown that Fourier’s law and the CV model cannot break equilibrium spontaneously by analyzing mathematical energy integral.
Thermodynamics of spin chains of Haldane-Shastry type and one-dimensional vertex models
Energy Technology Data Exchange (ETDEWEB)
Enciso, Alberto [Instituto de Ciencias Matematicas, Consejo Superior de Investigaciones Cientificas, 28049 Madrid (Spain); Finkel, Federico [Departamento de Fisica Teorica II, Universidad Complutense de Madrid, 28040 Madrid (Spain); Gonzalez-Lopez, Artemio, E-mail: artemio@fis.ucm.es [Departamento de Fisica Teorica II, Universidad Complutense de Madrid, 28040 Madrid (Spain)
2012-11-15
We study the thermodynamic properties of spin chains of Haldane-Shastry type associated with the A{sub N-1} root system in the presence of a uniform external magnetic field. To this end, we exactly compute the partition function of these models for an arbitrary finite number of spins. We then show that these chains are equivalent to a suitable inhomogeneous classical Ising model in a spatially dependent magnetic field, generalizing the results of Basu-Mallick et al. for the zero magnetic field case. Using the standard transfer matrix approach, we are able to compute in closed form the free energy per site in the thermodynamic limit. We perform a detailed analysis of the chains' thermodynamics in a unified way, with special emphasis on the zero field and zero temperature limits. Finally, we provide a novel interpretation of the thermodynamic quantities of spin chains of Haldane-Shastry type as weighted averages of the analogous quantities over an ensemble of classical Ising models. - Highlights: Black-Right-Pointing-Pointer Partition function of spin chains of Haldane-Shastry type in magnetic field. Black-Right-Pointing-Pointer Equivalence to classical inhomogeneous Ising models. Black-Right-Pointing-Pointer Free energy per site, other thermodynamic quantities in thermodynamic limit. Black-Right-Pointing-Pointer Zero field, zero temperature limits. Black-Right-Pointing-Pointer Thermodynamic equivalence with ensemble of classical Ising models.
Tomar, Dheeraj S.; Weber, Valéry; Pettitt, B. Montgomery; Asthagiri, D.
2014-01-01
The hydration thermodynamics of the amino acid X relative to the reference G (glycine) or the hydration thermodynamics of a small-molecule analog of the side chain of X is often used to model the contribution of X to protein stability and solution thermodynamics. We consider the reasons for successes and limitations of this approach by calculating and comparing the conditional excess free energy, enthalpy, and entropy of hydration of the isoleucine side chain in zwitterionic isoleucine, in ex...
Requirements for clinical information modelling tools.
Moreno-Conde, Alberto; Jódar-Sánchez, Francisco; Kalra, Dipak
2015-07-01
This study proposes consensus requirements for clinical information modelling tools that can support modelling tasks in medium/large scale institutions. Rather than identify which functionalities are currently available in existing tools, the study has focused on functionalities that should be covered in order to provide guidance about how to evolve the existing tools. After identifying a set of 56 requirements for clinical information modelling tools based on a literature review and interviews with experts, a classical Delphi study methodology was applied to conduct a two round survey in order to classify them as essential or recommended. Essential requirements are those that must be met by any tool that claims to be suitable for clinical information modelling, and if we one day have a certified tools list, any tool that does not meet essential criteria would be excluded. Recommended requirements are those more advanced requirements that may be met by tools offering a superior product or only needed in certain modelling situations. According to the answers provided by 57 experts from 14 different countries, we found a high level of agreement to enable the study to identify 20 essential and 21 recommended requirements for these tools. It is expected that this list of identified requirements will guide developers on the inclusion of new basic and advanced functionalities that have strong support by end users. This list could also guide regulators in order to identify requirements that could be demanded of tools adopted within their institutions. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
Modeling thermodynamic distance, curvature and fluctuations a geometric approach
Badescu, Viorel
2016-01-01
This textbook aims to briefly outline the main directions in which the geometrization of thermodynamics has been developed in the last decades. The textbook is accessible to people trained in thermal sciences but not necessarily with solid formation in mathematics. For this, in the first chapters a summary of the main mathematical concepts is made. In some sense, this makes the textbook self-consistent. The rest of the textbook consists of a collection of results previously obtained in this young branch of thermodynamics. The manner of presentation used throughout the textbook is adapted for ease of access of readers with education in natural and technical sciences.
Computer-Aided Modelling Methods and Tools
DEFF Research Database (Denmark)
Cameron, Ian; Gani, Rafiqul
2011-01-01
The development of models for a range of applications requires methods and tools. In many cases a reference model is required that allows the generation of application specific models that are fit for purpose. There are a range of computer aided modelling tools available that help to define...... a taxonomy of aspects around conservation, constraints and constitutive relations. Aspects of the ICAS-MoT toolbox are given to illustrate the functionality of a computer aided modelling tool, which incorporates an interface to MS Excel....
Energy Technology Data Exchange (ETDEWEB)
2015-05-15
MATK provides basic functionality to facilitate model analysis within the Python computational environment. Model analysis setup within MATK includes: - define parameters - define observations - define model (python function) - define samplesets (sets of parameter combinations) Currently supported functionality includes: - forward model runs - Latin-Hypercube sampling of parameters - multi-dimensional parameter studies - parallel execution of parameter samples - model calibration using internal Levenberg-Marquardt algorithm - model calibration using lmfit package - model calibration using levmar package - Markov Chain Monte Carlo using pymc package MATK facilitates model analysis using: - scipy - calibration (scipy.optimize) - rpy2 - Python interface to R
A Chemically Relevant Model for Teaching the Second Law of Thermodynamics.
Williamson, Bryce E.; Morikawa, Tetsuo
2002-01-01
Introduces a chemical model illustrating the aspects of the second law of thermodynamics which explains concepts such as reversibility, path dependence, and extrapolation in terms of electrochemistry and calorimetry. Presents a thought experiment using an ideal galvanic electrochemical cell. (YDS)
Thermodynamic model of hardness: Particular case of boron-rich solids
Mukhanov, V. A.; Kurakevych, O. O.; Solozhenko, V. L.
2011-01-01
A number of successful theoretical models of hardness have been developed recently. A thermodynamic model of hardness, which supposes the intrinsic character of correlation between hardness and thermodynamic properties of solids, allows one to predict hardness of known or even hypothetical solids from the data on Gibbs energy of atomization of the elements, which implicitly determine the energy density per chemical bonding. The only structural data needed is the coordination number of the ato...
Introduction to thermodynamics of spin models in the Hamiltonian limit
Berche, B; Berche, Bertrand; Lopez, Alexander
2006-01-01
A didactic description of the thermodynamic properties of classical spin systems is given in terms of their quantum counterpart in the Hamiltonian limit. Emphasis is on the construction of the relevant Hamiltonian, and the calculation of thermal averages is explicitly done in the case of small systems described, in Hamiltonian field theory, by small matrices.
The Ising model as a pedagogical tool
Smith, Ryan; Hart, Gus L. W.
2010-10-01
Though originally developed to analyze ferromagnetic systems, the Ising model also provides an excellent framework for modeling alloys. The original Ising model represented magnetic moments (up or down) by a +1 or -1 at each point on a lattice and allowed only nearest neighbors interactions to be non-zero. In alloy modeling, the values ±1 represent A and B atoms. The Ising Hamiltonian can be used in a Monte Carlo approach to simulate the thermodynamics of the system (e.g., an order-disorder transition occuring as the temperature is lowered). The simplicity of the model makes it an ideal starting point for a qualitative understanding of magnetism or configuration ordering in a metal. I will demonstrate the application of the Ising model in simple, two-dimensional ferromagnetic systems and alloys.
Hidayat, Taufiq; Shishin, Denis; Decterov, Sergei A.; Hayes, Peter C.; Jak, Evgueni
2017-01-01
Uncertainty in the metal price and competition between producers mean that the daily operation of a smelter needs to target high recovery of valuable elements at low operating cost. Options for the improvement of the plant operation can be examined and decision making can be informed based on accurate information from laboratory experimentation coupled with predictions using advanced thermodynamic models. Integrated high-temperature experimental and thermodynamic modelling research on phase equilibria and thermodynamics of copper-containing systems have been undertaken at the Pyrometallurgy Innovation Centre (PYROSEARCH). The experimental phase equilibria studies involve high-temperature equilibration, rapid quenching and direct measurement of phase compositions using electron probe X-ray microanalysis (EPMA). The thermodynamic modelling deals with the development of accurate thermodynamic database built through critical evaluation of experimental data, selection of solution models, and optimization of models parameters. The database covers the Al-Ca-Cu-Fe-Mg-O-S-Si chemical system. The gas, slag, matte, liquid and solid metal phases, spinel solid solution as well as numerous solid oxide and sulphide phases are included. The database works within the FactSage software environment. Examples of phase equilibria data and thermodynamic models of selected systems, as well as possible implementation of the research outcomes to selected copper making processes are presented.
Modelling of physical and thermodynamic properties in systems containing edible oils and biodiesel
DEFF Research Database (Denmark)
Cunico, Larissa; Ceriani, Roberta; Sarup, Bent
The knowledge of physical and thermodynamic properties of pure components and their mixtures is a basic requirement for performing tasks related to process design, simulation, and optimization and also for performing chemical product design using computer aided molecular/mixture design (CAMD) tools...
Generalized second law of thermodynamics for non-canonical scalar field model with corrected-entropy
Das, Sudipta; Debnath, Ujjal; Mamon, Abdulla Al
2015-10-01
In this work, we have considered a non-canonical scalar field dark energy model in the framework of flat FRW background. It has also been assumed that the dark matter sector interacts with the non-canonical dark energy sector through some interaction term. Using the solutions for this interacting non-canonical scalar field dark energy model, we have investigated the validity of generalized second law (GSL) of thermodynamics in various scenarios using first law and area law of thermodynamics. For this purpose, we have assumed two types of horizons viz apparent horizon and event horizon for the universe and using first law of thermodynamics, we have examined the validity of GSL on both apparent and event horizons. Next, we have considered two types of entropy-corrections on apparent and event horizons. Using the modified area law, we have examined the validity of GSL of thermodynamics on apparent and event horizons under some restrictions of model parameters.
Generalized Second Law of Thermodynamics for Non-canonical Scalar Field Model with Corrected-Entropy
Das, Sudipta; Mamon, Abdulla Al
2015-01-01
In this work, we have considered a non-canonical scalar field dark energy model in the framework of flat FRW background. It has also been assumed that the dark matter sector interacts with the non-canonical dark energy sector through some interaction term. Using the solutions for this interacting non-canonical scalar field dark energy model, we have investigated the validity of generalized second law (GSL) of thermodynamics in various scenarios using first law and area law of thermodynamics. For this purpose, we have assumed two types of horizons viz apparent horizon and event horizon for the universe and using first law of thermodynamics, we have examined the validity of GSL on both apparent and event horizons. Next, we have considered two types of entropy-corrections on apparent and event horizons. Using the modified area law, we have examined the validity of GSL of thermodynamics on apparent and event horizons under some restrictions of model parameters.
Generalized second law of thermodynamics for non-canonical scalar field model with corrected-entropy
Energy Technology Data Exchange (ETDEWEB)
Das, Sudipta; Mamon, Abdulla Al [Visva-Bharati, Department of Physics, Santiniketan (India); Debnath, Ujjal [Indian Institute of Engineering Science and Technology, Department of Mathematics, Shibpur, Howrah (India)
2015-10-15
In this work, we have considered a non-canonical scalar field dark energy model in the framework of flat FRW background. It has also been assumed that the dark matter sector interacts with the non-canonical dark energy sector through some interaction term. Using the solutions for this interacting non-canonical scalar field dark energy model, we have investigated the validity of generalized second law (GSL) of thermodynamics in various scenarios using first law and area law of thermodynamics. For this purpose, we have assumed two types of horizons viz apparent horizon and event horizon for the universe and using first law of thermodynamics, we have examined the validity of GSL on both apparent and event horizons. Next, we have considered two types of entropy-corrections on apparent and event horizons. Using the modified area law, we have examined the validity of GSL of thermodynamics on apparent and event horizons under some restrictions of model parameters. (orig.)
Software Engineering Tools for Scientific Models
Abrams, Marc; Saboo, Pallabi; Sonsini, Mike
2013-01-01
Software tools were constructed to address issues the NASA Fortran development community faces, and they were tested on real models currently in use at NASA. These proof-of-concept tools address the High-End Computing Program and the Modeling, Analysis, and Prediction Program. Two examples are the NASA Goddard Earth Observing System Model, Version 5 (GEOS-5) atmospheric model in Cell Fortran on the Cell Broadband Engine, and the Goddard Institute for Space Studies (GISS) coupled atmosphere- ocean model called ModelE, written in fixed format Fortran.
Thermodynamic properties of a quasi-harmonic model for ferroelectric transitions
Energy Technology Data Exchange (ETDEWEB)
Mkam Tchouobiap, S E [Laboratory of Research on Advanced Materials and Nonlinear Sciences (LaRAMaNS), Department of Physics, Faculty of Science, University of Buea, PO Box 63, Buea (Cameroon); Mashiyama, H, E-mail: esmkam@yahoo.com [Department of Physics, Faculty of Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8512 (Japan)
2011-03-30
Within a framework of a quasi-harmonic model for quantum particles in a local potential of the double Morse type and within the mean-field approximation for interactions between particles, we investigate the thermodynamic properties of ferroelectric materials. A quantum thermodynamic treatment gives analytic expressions for the internal energy, the entropy, the specific heat, and the static susceptibility. The calculated thermodynamic characteristics are studied as a function of temperature and energy barrier, where it is shown that at the proper choice of the theory parameters, particularly the energy barrier, the model system exhibits characteristic features of either second-order tricritical or first-order phase transitions. Our results indicate that the barrier energy seems to be an important criterion for the character of the structural phase transition. The influence of quantum fluctuations manifested on zero-point energy on the phase transition and thermodynamic properties is analyzed and discussed. This leads to several quantum effects, including the existence of a saturation regime at low temperatures, where the order parameter saturates giving thermodynamic saturation of the calculated thermodynamic quantities. It is found that both quantum effects and energy barrier magnitude have an important influence on the thermodynamic properties of the ferroelectric materials and on driving the phase transition at low temperatures. Also, the analytical parameters' effect on the transition temperature is discussed, which seems to give a general insight into the structural phase transition and its nature.
Energy Technology Data Exchange (ETDEWEB)
Andren, Hans-Olof
2003-07-25
Atom probe field ion microscopy (APFIM) gives accurate data on phase composition for all elements and has a good sensitivity and excellent spatial resolution. APFIM data have therefore been used as support for thermodynamic modelling of phase equilibria and phase transformations. This paper describes a number of cases where atom probe data from Chalmers University have been used to judge the accuracy of modelling: the solubility of W and C in Co, the equilibrium volume fraction of VN in a complex chromium steel, the content of B in M{sub 23}C{sub 6} precipitates, the growth of Laves phase during ageing of a chromium steel, and the growth of secondary NbC precipitates in a stabilised austenitic stainless steel. Atomistic modelling is now emerging as a tool for materials science, in particular for modelling of interfacial structure and energies. The status of the activities in this field at Chalmers University is described, and the role of APFIM in atomistic modelling is discussed.
Model uncertainties of local-thermodynamic-equilibrium K-shell spectroscopy
Nagayama, T.; Bailey, J. E.; Mancini, R. C.; Iglesias, C. A.; Hansen, S. B.; Blancard, C.; Chung, H. K.; Colgan, J.; Cosse, Ph.; Faussurier, G.; Florido, R.; Fontes, C. J.; Gilleron, F.; Golovkin, I. E.; Kilcrease, D. P.; Loisel, G.; MacFarlane, J. J.; Pain, J.-C.; Rochau, G. A.; Sherrill, M. E.; Lee, R. W.
2016-09-01
Local-thermodynamic-equilibrium (LTE) K-shell spectroscopy is a common tool to diagnose electron density, ne, and electron temperature, Te, of high-energy-density (HED) plasmas. Knowing the accuracy of such diagnostics is important to provide quantitative conclusions of many HED-plasma research efforts. For example, Fe opacities were recently measured at multiple conditions at the Sandia National Laboratories Z machine (Bailey et al., 2015), showing significant disagreement with modeled opacities. Since the plasma conditions were measured using K-shell spectroscopy of tracer Mg (Nagayama et al., 2014), one concern is the accuracy of the inferred Fe conditions. In this article, we investigate the K-shell spectroscopy model uncertainties by analyzing the Mg spectra computed with 11 different models at the same conditions. We find that the inferred conditions differ by ±20-30% in ne and ±2-4% in Te depending on the choice of spectral model. Also, we find that half of the Te uncertainty comes from ne uncertainty. To refine the accuracy of the K-shell spectroscopy, it is important to scrutinize and experimentally validate line-shape theory. We investigate the impact of the inferred ne and Te model uncertainty on the Fe opacity measurements. Its impact is small and does not explain the reported discrepancies.
DEFF Research Database (Denmark)
Faramarzi, Leila; Kontogeorgis, Georgios; Thomsen, Kaj
2009-01-01
The extended UNIQUAC model [K. Thomsen, R Rasmussen, Chem. Eng. Sci. 54 (1999) 1787-1802] was applied to the thermodynamic representation of carbon dioxide absorption in aqueous monoethanolamine (MEA), methyldiethanolamine (MDEA) and varied strength mixtures of the two alkanolamines (MEA-MDEA). F......The extended UNIQUAC model [K. Thomsen, R Rasmussen, Chem. Eng. Sci. 54 (1999) 1787-1802] was applied to the thermodynamic representation of carbon dioxide absorption in aqueous monoethanolamine (MEA), methyldiethanolamine (MDEA) and varied strength mixtures of the two alkanolamines (MEA......) are included in the parameter estimation process. The previously unavailable standard state properties of the alkanolamine ions appearing in this work, i.e. MEA protonate, MEA carbamate and MDEA protonate are determined. The concentration of the species in both MEA and MDEA solutions containing CO2...
Botvina, A; Gupta, S Das; Mishustin, I
2008-01-01
The statistical multifragmentation model (SMM) has been widely used to explain experimental data of intermediate energy heavy ion collisions. A later entrant in the field is the canonical thermodynamic model (CTM) which is also being used to fit experimental data. The basic physics of both the models is the same, namely that fragments are produced according to their statistical weights in the available phase space. However, they are based on different statistical ensembles, and the methods of calculation are different: while the SMM uses Monte-Carlo simulations, the CTM solves recursion relations. In this paper we compare the predictions of the two models for a few representative cases.
A development of multi-Species mass transport model considering thermodynamic phase equilibrium
DEFF Research Database (Denmark)
Hosokawa, Yoshifumi; Yamada, Kazuo; Johannesson, Björn
2008-01-01
In this paper, a multi-species mass transport model, which can predict time dependent variation of pore solution and solid-phase composition due to the mass transport into the hardened cement paste, has been developed. Since most of the multi-species models established previously, based...... by the penetration of mineral salts during marine seawater exposure conditions. Those phenomena in concrete can be predicted using the coupled multi-species mass transport model and the thermodynamic equilibrium model described in this paper....... on the Poisson-Nernst-Planck theory, did not involve the modeling of chemical process, it has been coupled to thermodynamic equilibrium model in this study. By the coupling of thermodynamic equilibrium model, the multi-species model could simulate many different behaviours in hardened cement paste such as: (i...
Simulation Tool for Inventory Models: SIMIN
Pratiksha Saxen; Tulsi Kushwaha
2014-01-01
In this paper, an integrated simulation optimization model for the inventory system is developed. An effective algorithm is developed to evaluate and analyze the back-end stored simulation results. This paper proposes simulation tool SIMIN (Inventory Simulation) to simulate inventory models. SIMIN is a tool which simulates and compares the results of different inventory models. To overcome various practical restrictive assumptions, SIMIN provides values for a number of performance measurement...
Directory of Open Access Journals (Sweden)
Abdallah Haouam
2012-03-01
Full Text Available Samples of Inconel 600 were isothermally oxidized in a controlled atmosphere with a special mounting at high-temperature oxidation. Along with this experimental study, a simulation of thermodynamic behavior of the material in the same oxidation conditions was carried out using the Thermo-Calc code. The thermodynamic modeling is able to predict the phase nature and its distribution in the structure of the surface layer resulting from the corrosion of the material in thermodynamic equilibrium in the absence of mechanical stress. The results of this simulation are supplemented to results obtained from the analysis by glow discharge spectrometry (GDS which is performed on the samples tested.
Computational Models of Thermodynamic Properties of Uranium Nitride
Mei, Zhi-Gang; Stan, Marius
2014-06-01
The structural, elastic, electronic, phonon and thermodynamic properties of uranium nitride (UN) have been systematically studied by density functional theory (DFT) calculations. The calculated electronic band structure shows that UN is a metallic phase. The ground state structural and elastic properties predicted by DFT agree well with experiments. The thermodynamic properties of UN are studied by quasiharmonic approximation by including both lattice vibrational and thermal electronic contributions to free energies. The calculated enthalpy, entropy, Gibbs energy and heat capacity show an excellent agreement with experimental results. The thermal electronic contribution due to 5f electrons of U is found to be critical to describe the free energy of UN due to its metallic character.
Quantum thermodynamics for a model of an expanding universe
Liu, Nana; Fuentes, Ivette; Vedral, Vlatko; Modi, Kavan; Bruschi, David Edward
2016-01-01
We investigate the thermodynamical properties of quantum fields in curved spacetime. Our approach is to consider quantum fields in curved spacetime as a quantum system undergoing an out-of-equilibrium transformation. The non-equilibrium features are studied by using a formalism which has been developed to derive fluctuation relations and emergent irreversible features beyond the linear response regime. We apply these ideas to an expanding universe scenario, therefore avoiding assumptions on the relation between entropy and quantum matter. We provide a fluctuation theorem which allows us to understand particle production due to the expansion of the universe as an entropic increase. Our results pave the way towards a different understanding of the thermodynamics of relativistic and quantum systems in our universe.
Modelling plasticity of unsaturated soils in a thermodynamically consistent framework
Coussy, O
2010-01-01
Constitutive equations of unsaturated soils are often derived in a thermodynamically consistent framework through the use a unique 'effective' interstitial pressure. This later is naturally chosen as the space averaged interstitial pressure. However, experimental observations have revealed that two stress state variables were needed to describe the stress-strain-strength behaviour of unsaturated soils. The thermodynamics analysis presented here shows that the most general approach to the behaviour of unsaturated soils actually requires three stress state variables: the suction, which is required to describe the retention properties of the soil and two effective stresses, which are required to describe the soil deformation at water saturation held constant. Actually, it is shown that a simple assumption related to internal deformation leads to the need of a unique effective stress to formulate the stress-strain constitutive equation describing the soil deformation. An elastoplastic framework is then presented ...
Faroongsarng, Damrongsak
2016-06-01
Although differential scanning calorimetry (DSC) is a non-equilibrium technique, it has been used to gain energetic information that involves phase equilibria. DSC has been widely used to characterize the equilibrium melting parameters of small organic pharmaceutical compounds. An understanding of how DSC measures an equilibrium event could make for a better interpretation of the results. The aim of this mini-review was to provide a theoretical insight into the DSC measurement to obtain the equilibrium thermodynamics of a phase transition especially the melting process. It was demonstrated that the heat quantity obtained from the DSC thermogram (ΔH) was related to the thermodynamic enthalpy of the phase transition (ΔH (P) ) via: ΔH = ΔH (P) /(1 + K (- 1)) where K was the equilibrium constant. In melting, the solid and liquefied phases presumably coexist resulting in a null Gibbs free energy that produces an infinitely larger K. Thus, ΔH could be interpreted as ΔH (P). Issues of DSC investigations on melting behavior of crystalline solids including polymorphism, degradation impurity due to heating in situ, and eutectic melting were discussed. In addition, DSC has been a tool for determination of the impurity based on an ideal solution of the melt that is one of the official methods used to establish the reference standard.
Thermodynamics of a physical model implementing a Maxwell demon
Strasberg, Philipp; Schaller, Gernot; Brandes, Tobias; Esposito, Massimiliano
2012-01-01
We present a physical implementation of a Maxwell demon which consists of a conventional single electron transistor (SET) capacitively coupled to another quantum dot detecting its state. Altogether, the system is described by stochastic thermodynamics. We identify the regime where the energetics of the SET is not affected by the detection, but where its coarse-grained entropy production is shown to contain a new contribution compared to the isolated SET. This additional contributi...
Thermodynamics of water modeled using ab initio simulations
Weber, Valéry
2010-01-01
We regularize the potential distribution framework to calculate the excess free energy of liquid water simulated with the BLYP-D density functional. The calculated free energy is in fair agreement with experiments but the excess internal energy and hence also the excess entropy are not. Our work emphasizes the importance of thermodynamic characterization in assessing the quality of electron density functionals in describing liquid water and hydration phenomena.
Cantera Integration with the Toolbox for Modeling and Analysis of Thermodynamic Systems (T-MATS)
Lavelle, Thomas M.; Chapman, Jeffryes W.; May, Ryan D.; Litt, Jonathan S.; Guo, Ten-Huei
2014-01-01
NASA Glenn Research Center (GRC) has recently developed a software package for modeling generic thermodynamic systems called the Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS). T-MATS is a library of building blocks that can be assembled to represent any thermodynamic system in the Simulink (The MathWorks, Inc.) environment. These elements, along with a Newton Raphson solver (also provided as part of the T-MATS package), enable users to create models of a wide variety of systems. The current version of T-MATS (v1.0.1) uses tabular data for providing information about a specific mixture of air, water (humidity), and hydrocarbon fuel in calculations of thermodynamic properties. The capabilities of T-MATS can be expanded by integrating it with the Cantera thermodynamic package. Cantera is an object-oriented analysis package that calculates thermodynamic solutions for any mixture defined by the user. Integration of Cantera with T-MATS extends the range of systems that may be modeled using the toolbox. In addition, the library of elements released with Cantera were developed using MATLAB native M-files, allowing for quicker prototyping of elements. This paper discusses how the new Cantera-based elements are created and provides examples for using T-MATS integrated with Cantera.
Ali, Ashraf; Lovell, Michael
1995-08-01
This presentation summarizes the capabilities in the ANSYS program that relate to the computational modeling of tires. The power and the difficulties associated with modeling nearly incompressible rubber-like materials using hyperelastic constitutive relationships are highlighted from a developer's point of view. The topics covered include a hyperelastic material constitutive model for rubber-like materials, a general overview of contact-friction capabilities, and the acoustic fluid-structure interaction problem for noise prediction. Brief theoretical development and example problems are presented for each topic.
Solution chemistry of Mo(III) and Mo(IV): Thermodynamic foundation for modeling localized corrosion
Energy Technology Data Exchange (ETDEWEB)
Wang Peiming [OLI Systems Inc., 108 American Road, Morris Plains, NJ 07950 (United States); Wilson, Leslie L.; Wesolowski, David J.; Rosenqvist, Joergen [Chemical Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831-6110 (United States); Anderko, Andrzej [OLI Systems Inc., 108 American Road, Morris Plains, NJ 07950 (United States)], E-mail: aanderko@olisystems.com
2010-05-15
To investigate the behavior of molybdenum dissolution products in systems that approximate localized corrosion environments, solubility of Mo(III) in equilibrium with solid MoO{sub 2} has been determined at 80 deg. C as a function of solution acidity, chloride concentration and partial pressure of hydrogen. The measurements indicate a strong increase in solubility with acidity and chloride concentration and a weak effect of hydrogen partial pressure. The obtained results have been combined with literature data for systems containing Mo(III), Mo(IV), and Mo(VI) in solutions to develop a comprehensive thermodynamic model of aqueous molybdenum chemistry. The model is based on a previously developed framework for simulating the properties of electrolyte systems ranging from infinite dilution to solid saturation or fused salt limit. To reproduce the measurements, the model assumes the presence of a chloride complex of Mo(III) (i.e., MoCl{sup 2+}) and hydrolyzed species (MoOH{sup 2+}, Mo(OH){sub 2}{sup +}, and Mo(OH){sub 3}{sup 0}) in addition to the Mo{sup 3+} ion. The model generally reproduces the experimental data within experimental scattering and provides a tool for predicting the phase behavior and speciation in complex, concentrated aqueous solutions. Thus, it provides a foundation for simulating the behavior of molybdenum species in localized corrosion environments.
Gas turbine cooling modeling - Thermodynamic analysis and cycle simulations
Energy Technology Data Exchange (ETDEWEB)
Jordal, Kristin
1999-02-01
Considering that blade and vane cooling are a vital point in the studies of modern gas turbines, there are many ways to include cooling in gas turbine models. Thermodynamic methods for doing this are reviewed in this report, and, based on some of these methods, a number of model requirements are set up and a Cooled Gas Turbine Model (CGTM) for design-point calculations of cooled gas turbines is established. Thereafter, it is shown that it is possible to simulate existing gas turbines with the CGTM. Knowledge of at least one temperature in the hot part of the turbine (TET, TRIT or possibly TIT) is found to be vital for a complete heat balance over the turbine. The losses, which are caused by the mixing of coolant and main flow, are in the CGTM considered through a polytropic efficiency reduction factor S. Through the study of S, it can be demonstrated that there is more to gain from coolant reduction in a small and/or old turbine with poor aerodynamics, than there is to gain in a large, modern turbine, where the losses due to interaction between coolant and main flow are, relatively speaking, small. It is demonstrated, at the design point (TET=1360 deg C, {pi}=20) for the simple-cycle gas turbine, that heat exchanging between coolant and fuel proves to have a large positive impact on cycle efficiency, with an increase of 0.9 percentage points if all of the coolant passes through the heat exchanger. The corresponding improvement for humidified coolant is 0.8 percentage points. A design-point study for the HAT cycle shows that if all of the coolant is extracted after the humidification tower, there is a decrease in coolant requirements of 7.16 percentage points, from 19.58% to 12.52% of the compressed air, and an increase in thermal efficiency of 0.46 percentage points, from 53.46% to 53.92%. Furthermore, it is demonstrated with a TET-parameter variation, that the cooling of a simple-cycle gas turbine with humid air can have a positive effect on thermal efficiency
STUDY ON THERMODYNAMIC MODEL OF A COMPRESSOR WITH ARTIFICIAL NEURAL NETWORKS
Institute of Scientific and Technical Information of China (English)
无
1999-01-01
A new compressor thermodynamic model is set up. Artificial neural networks(ANN) which have self-adjusting functions are adopted to calculate volumetric efficiency and electrical efficiency of a compressor. The new compressor model composed of the theoretical model and ANN reaches more precise results than traditional ones. Furthermore, the new compressor model is of better flexibility in a large scale.
Thermodynamic studies of spin-1/2 Falicov-Kimball model (FKM) on a triangular lattice
Energy Technology Data Exchange (ETDEWEB)
Kumar, Sant, E-mail: santkumar1210@gmail.com; Maitra, Tulika; Singh, Ishwar [Department of Physics, Indian Institute of Technology Roorkee, Roorkee-247667, Uttarakhand (India); Yadav, Umesh K. [Center for Condensed Matter Theory, Indian Institute of Science Bangalore-560012 (India)
2016-05-23
Thermodynamic properties of the spin-dependent Falicov-Kimball model are studied on a triangular lattice for one-fourth filled case. Numerical diagonalization and Monte-Carlo simulation are used to study the thermodynamic properties. Continuous phase transitions are observed at finite temperature. We have observed that critical temperature (Tc) increases with the increase in on-site Coulomb correlation U. The second order nature of the transition is also revealed from the temperature dependence of specific heat.
Thermodynamic studies of spin-1/2 Falicov-Kimball model (FKM) on a triangular lattice
Kumar, Sant; Yadav, Umesh K.; Maitra, Tulika; Singh, Ishwar
2016-05-01
Thermodynamic properties of the spin-dependent Falicov-Kimball model are studied on a triangular lattice for one-fourth filled case. Numerical diagonalization and Monte-Carlo simulation are used to study the thermodynamic properties. Continuous phase transitions are observed at finite temperature. We have observed that critical temperature (Tc) increases with the increase in on-site Coulomb correlation U. The second order nature of the transition is also revealed from the temperature dependence of specific heat.
Thermodynamic modelling of acid gas removal from natural gas using the Extended UNIQUAC model
DEFF Research Database (Denmark)
Sadegh, Negar; Stenby, Erling Halfdan; Thomsen, Kaj
2017-01-01
Thermodynamics of natural gas sweetening process needs to be known for proper design of natural gas treating plants. Absorption with aqueous N-Methyldiethanolamine is currently the most commonly used process for removal of acid gas (CO2 and H2S) impurities from natural gas. Model parameters...... for the Extended UNIQUAC model have already been determined by the same authors to calculate single acid gas solubility in aqueous MDEA. In this study, the model is further extended to estimate solubility of CO2 and H2S and their mixture in aqueous MDEA at high pressures with methane as a makeup gas....
Thermodynamics of Biological Processes
Garcia, Hernan G.; Kondev, Jane; Orme, Nigel; Theriot, Julie A.; Phillips, Rob
2012-01-01
There is a long and rich tradition of using ideas from both equilibrium thermodynamics and its microscopic partner theory of equilibrium statistical mechanics. In this chapter, we provide some background on the origins of the seemingly unreasonable effectiveness of ideas from both thermodynamics and statistical mechanics in biology. After making a description of these foundational issues, we turn to a series of case studies primarily focused on binding that are intended to illustrate the broad biological reach of equilibrium thinking in biology. These case studies include ligand-gated ion channels, thermodynamic models of transcription, and recent applications to the problem of bacterial chemotaxis. As part of the description of these case studies, we explore a number of different uses of the famed Monod–Wyman–Changeux (MWC) model as a generic tool for providing a mathematical characterization of two-state systems. These case studies should provide a template for tailoring equilibrium ideas to other problems of biological interest. PMID:21333788
Energy Technology Data Exchange (ETDEWEB)
Wolery, Thomas J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Tayne, Andrew [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Jove-Colon, Carlos F. [Sandia National Lab. (SNL-CA), Livermore, CA (United States)
2011-07-29
Thermodynamic data are essential for understanding and evaluating geochemical processes, as by speciation-solubility calculations, reaction -path modeling, or reactive transport simulation. These data are required to evaluate both equilibrium states and the kinetic approach to such states (via the affinity term in rate laws). The development of thermodynamic databases for these purposes has a long history in geochemistry (e.g., Garrels and Christ, 1965; Helgeson et al., 1969; Helgeson et al., 1978, Johnson et al., 1992; Robie and Hemingway, 1995), paralleled by related and applicable work in the larger scientific community (e.g., Wagman et al., 1982, 1989; Cox et al., 1989; Barin and Platzki, 1995; Binneweis and Milke, 1999). The Yucca Mountain Project developed two qualified thermodynamic databases for to model geochemical processes, including ones involving repository components such as spent fuel. The first of the two (BSC, 2007a) was for systems containing dilute aqueous solutions only, the other (BSC, 2007b) for systems involving concentrated aqueous solutions and incorporating a model for such based on Pitzer’s (1991) equations . A 25°C-only database with similarities to the latter was also developed for WIPP (cf. Xiong, 2005). The YMP dilute systems database is widely used in the geochemistry community for a variety of applications involving rock/water interactions. The purpose of the present task is to improve these databases for work on the Used Fuel Disposition Project and maintain some semblance of order that will support qualification in support of the development of future underground high level nuclear waste disposal.
Energy Technology Data Exchange (ETDEWEB)
Xiao Yamping; Holappa, L. [Helsinki Univ. of Technology, Otaniemi (Finland). Lab. of Metallurgy
1996-12-31
This article summaries the research work on thermodynamics of chromium slags and kinetic modelling of chromite reduction. The thermodynamic properties of FeCr slag systems were calculated with the regular solution model. The effects of CaO/MgO ratio, Al{sub 2}0{sub 3} amount as well as the slag basicity on the activities of chromium oxides and the oxidation state of chromium were examined. The calculated results were compared to the experimental data in the literature. In the kinetic modelling of the chromite reduction, the reduction possibilities and tendencies of the chromite constitutes with CO were analysed based on the thermodynamic calculation. Two reaction models, a structural grain model and a multi-layers reaction model, were constructed and applied to simulate the chromite pellet reduction and chromite lumpy ore reduction, respectively. The calculated reduction rates were compared with the experimental measurements and the reaction mechanisms were discussed. (orig.) SULA 2 Research Programme; 4 refs.
Energy Technology Data Exchange (ETDEWEB)
Lo, Ch. K.; Lim, Y. S.; Tan, S. G.; Rahman, F. A. [Faculty of Engineering and Science, University Tunku Abdul Rahman, Jalan Genting Klang, 53300, Kuala Lumpur (Malaysia)
2010-12-15
A Luminescent Solar Concentrator (LSC) is a transparent plate containing luminescent material with photovoltaic (PV) cells attached to its edges. Sunlight entering the plate is absorbed by the luminescent material, which in turn emits light. The emitted light propagates through the plate and arrives at the PV cells through total internal reflection. The ratio of the area of the relatively cheap polymer plate to that of the expensive PV cells is increased, and the cost per unit of solar electricity can be reduced by 75%. To improve the emission performance of LSCs, simulation modeling of LSCs becomes essential. Ray-tracing modeling is a popular approach for simulating LSCs due to its great ability of modeling various LSC structures under direct and diffuse sunlight. However, this approach requires substantial amount of measurement input data. Also, the simulation time is enormous because it is a forward-ray tracing method that traces all the rays propagating from the light source to the concentrator. On the other hand, the thermodynamic approach requires substantially less input parameters and simulation time, but it can only be used to model simple LSC designs with direct sunlight. Therefore, a new hybrid model was developed to perform various simulation studies effectively without facing the issues arisen from the existing ray-tracing and thermodynamic models. The simulation results show that at least 60% of the total output irradiance of a LSC is contributed by the light trapped and channeled by the LSC. The novelty of this hybrid model is the concept of integrating the thermodynamic model with a well-developed Radiance ray-tracing model, hence making this model as a fast, powerful and cost-effective tool for the design of LSCs. (authors)
Directory of Open Access Journals (Sweden)
Chin Kim Lo
2010-11-01
Full Text Available A Luminescent Solar Concentrator (LSC is a transparent plate containing luminescent material with photovoltaic (PV cells attached to its edges. Sunlight entering the plate is absorbed by the luminescent material, which in turn emits light. The emitted light propagates through the plate and arrives at the PV cells through total internal reflection. The ratio of the area of the relatively cheap polymer plate to that of the expensive PV cells is increased, and the cost per unit of solar electricity can be reduced by 75%. To improve the emission performance of LSCs, simulation modeling of LSCs becomes essential. Ray-tracing modeling is a popular approach for simulating LSCs due to its great ability of modeling various LSC structures under direct and diffuse sunlight. However, this approach requires substantial amount of measurement input data. Also, the simulation time is enormous because it is a forward-ray tracing method that traces all the rays propagating from the light source to the concentrator. On the other hand, the thermodynamic approach requires substantially less input parameters and simulation time, but it can only be used to model simple LSC designs with direct sunlight. Therefore, a new hybrid model was developed to perform various simulation studies effectively without facing the issues arisen from the existing ray-tracing and thermodynamic models. The simulation results show that at least 60% of the total output irradiance of a LSC is contributed by the light trapped and channeled by the LSC. The novelty of this hybrid model is the concept of integrating the thermodynamic model with a well-developed Radiance ray-tracing model, hence making this model as a fast, powerful and cost-effective tool for the design of LSCs.
Comparison of two different modelling tools
DEFF Research Database (Denmark)
Brix, Wiebke; Elmegaard, Brian
2009-01-01
In this paper a test case is solved using two different modelling tools, Engineering Equation Solver (EES) and WinDali, in order to compare the tools. The system of equations solved, is a static model of an evaporator used for refrigeration. The evaporator consists of two parallel channels......, and it is investigated how a non-uniform airflow influences the refrigerant mass flow rate distribution and the total cooling capacity of the heat exchanger. It is shown that the cooling capacity decreases significantly with increasing maldistribution of the airflow. Comparing the two simulation tools it is found...
A numerical model on thermodynamic analysis of free piston Stirling engines
Mou, Jian; Hong, Guotong
2017-02-01
In this paper, a new numerical thermodynamic model which bases on the energy conservation law has been used to analyze the free piston Stirling engine. In the model all data was taken from a real free piston Stirling engine which has been built in our laboratory. The energy conservation equations have been applied to expansion space and compression space of the engine. The equation includes internal energy, input power, output power, enthalpy and the heat losses. The heat losses include regenerative heat conduction loss, shuttle heat loss, seal leakage loss and the cavity wall heat conduction loss. The numerical results show that the temperature of expansion space and the temperature of compression space vary with the time. The higher regeneration effectiveness, the higher efficiency and bigger output work. It is also found that under different initial pressures, the heat source temperature, phase angle and engine work frequency pose different effects on the engine’s efficiency and power. As a result, the model is expected to be a useful tool for simulation, design and optimization of Stirling engines.
Directory of Open Access Journals (Sweden)
Liliana Giraldo
2008-10-01
Full Text Available The interaction of guest molecules ranging from pentan-1-ol to octan-1-ol with ÃŽÂ±-cyclodextrin (ÃŽÂ±-CD in water of has been studied calorimetrically at 283.15, 288.15, 293.15, 298.15 and 308.15 K with an isoperibolic titration calorimeter designed in our laboratory. The calorimetric method employed allows the determination of the thermodynamic parameters characterizing the binding process, ÃŽÂ”GÃ‚Â°m, ÃŽÂ”HÃ‚Â°m, ÃŽÂ”SÃ‚Â°mand ÃŽÂ”CpÃ‚Â°, namely free energy, enthalpy, and calorific capacity. These results show that in the temperature range investigated, the entropy change increased with chain length. This is in line with what is expected for a hydrophobic dehydration process. However, that effect is not expected to lead to the more pronounced negative CH2-increment observed for nc > 5 or 6. As for many other ligand binding processes, we can observe a significant enthalpy - entropy compensation for this system, both with respect to temperature and structure.
Thermodynamic Modeling as a Strategy for Casting High Alloy Steels
Institute of Scientific and Technical Information of China (English)
Peri Reddy V; S Raman Sankaranarayanan
2009-01-01
Strategies based on thermodynamic calculations can be used to overcome the problems associated with oxides encountered in steel plant operations, which can lead to certain difficulties in the process such as clogging of submerged entry nozzle during continuous casting. Approaches to producing high alloy steels by continuous casting have been taken. One of the strategies to avoid the oxidation of chromium is to add a small amount of other elements (subject to other constraints), which do not cause subsequent problems. The problem has been studied using the Thermo-CalcR software, with related databases; and the results obtained for different process conditions or generic com-positions have been presented.
Cockpit System Situational Awareness Modeling Tool
Keller, John; Lebiere, Christian; Shay, Rick; Latorella, Kara
2004-01-01
This project explored the possibility of predicting pilot situational awareness (SA) using human performance modeling techniques for the purpose of evaluating developing cockpit systems. The Improved Performance Research Integration Tool (IMPRINT) was combined with the Adaptive Control of Thought-Rational (ACT-R) cognitive modeling architecture to produce a tool that can model both the discrete tasks of pilots and the cognitive processes associated with SA. The techniques for using this tool to predict SA were demonstrated using the newly developed Aviation Weather Information (AWIN) system. By providing an SA prediction tool to cockpit system designers, cockpit concepts can be assessed early in the design process while providing a cost-effective complement to the traditional pilot-in-the-loop experiments and data collection techniques.
Theoretical models for fluid thermodynamics based on the quasi-Gaussian entropy theory
Amadei, Andrea
1998-01-01
Summary The theoretical modeling of fluid thermodynamics is one of the most challenging fields in physical chemistry. In fact the fluid behavior, except at very low density conditions, is still extremely difficult to be modeled from a statistical mechanical point of view, as for any realistic model
Hamilton, Joshua J; Dwivedi, Vivek; Reed, Jennifer L
2013-07-16
Constraint-based methods provide powerful computational techniques to allow understanding and prediction of cellular behavior. These methods rely on physiochemical constraints to eliminate infeasible behaviors from the space of available behaviors. One such constraint is thermodynamic feasibility, the requirement that intracellular flux distributions obey the laws of thermodynamics. The past decade has seen several constraint-based methods that interpret this constraint in different ways, including those that are limited to small networks, rely on predefined reaction directions, and/or neglect the relationship between reaction free energies and metabolite concentrations. In this work, we utilize one such approach, thermodynamics-based metabolic flux analysis (TMFA), to make genome-scale, quantitative predictions about metabolite concentrations and reaction free energies in the absence of prior knowledge of reaction directions, while accounting for uncertainties in thermodynamic estimates. We applied TMFA to a genome-scale network reconstruction of Escherichia coli and examined the effect of thermodynamic constraints on the flux space. We also assessed the predictive performance of TMFA against gene essentiality and quantitative metabolomics data, under both aerobic and anaerobic, and optimal and suboptimal growth conditions. Based on these results, we propose that TMFA is a useful tool for validating phenotypes and generating hypotheses, and that additional types of data and constraints can improve predictions of metabolite concentrations.
A thermodynamically consistent phase-field model for two-phase flows with thermocapillary effects
Guo, Zhenlin
2014-01-01
In this paper, we develop a phase-field model for binary incompressible fluid with thermocapillary effects, which allows the different properties (densities, viscosities and heat conductivities) for each component and meanwhile maintains the thermodynamic consistency. The governing equations of the model including the Navier-Stokes equations, Cahn-Hilliard equations and energy balance equation are derived together within a thermodynamic framework based on the entropy generation, which guarantees the thermodynamic consistency. The sharp-interface limit analysis is carried out to show that the interfacial conditions of the classical sharp-interface models can be recovered from our phase-field model. Moreover, some numerical examples including thermocapillary migration of a bubble and thermocapillary convections in a two- layer fluid system are computed by using a continuous finite element method. The results are compared to the existing analytical solutions and theoretical predictions as validations for our mod...
Size-dependent melting of nanoparticles: Hundred years of thermodynamic model
Indian Academy of Sciences (India)
K K Nanda
2009-04-01
Thermodynamic model first published in 1909, is being used extensively to understand the size-dependent melting of nanoparticles. Pawlow deduced an expression for the size-dependent melting temperature of small particles based on the thermodynamic model which was then modified and applied to different nanostructures such as nanowires, prism-shaped nanoparticles, etc. The model has also been modified to understand the melting of supported nanoparticles and superheating of embedded nanoparticles. In this article, we have reviewed the melting behaviour of nanostructures reported in the literature since 1909.
Recent Advances in Study on Thermodynamic Models for Real Systems Including Electrolytes
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
A comprehensive review of recent advances in study on thermodynamic models for real electrolyte solutions is presented. The differences between primitive and non-primitive electrolyte models are demonstrated. Some new thermodynamic models for electrolyte solutions based on the mean spherical approximation and perturbation theory are introduced. An extended scaled-particle theory and modified CleggPitz er equation are presented for physical and chemical absorption processes with mixed solvents, respectively. A pseudo one-component two-Yukawa equation of state is used for the aqueous two-phase extraction process in charged colloidal systems.
Thermodynamic Modeling of Organic-Inorganic Aerosols with the Group-Contribution Model AIOMFAC
Zuend, A.; Marcolli, C.; Luo, B. P.; Peter, T.
2009-04-01
Liquid aerosol particles are - from a physicochemical viewpoint - mixtures of inorganic salts, acids, water and a large variety of organic compounds (Rogge et al., 1993; Zhang et al., 2007). Molecular interactions between these aerosol components lead to deviations from ideal thermodynamic behavior. Strong non-ideality between organics and dissolved ions may influence the aerosol phases at equilibrium by means of liquid-liquid phase separations into a mainly polar (aqueous) and a less polar (organic) phase. A number of activity models exists to successfully describe the thermodynamic equilibrium of aqueous electrolyte solutions. However, the large number of different, often multi-functional, organic compounds in mixed organic-inorganic particles is a challenging problem for the development of thermodynamic models. The group-contribution concept as introduced in the UNIFAC model by Fredenslund et al. (1975), is a practical method to handle this difficulty and to add a certain predictability for unknown organic substances. We present the group-contribution model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients), which explicitly accounts for molecular interactions between solution constituents, both organic and inorganic, to calculate activities, chemical potentials and the total Gibbs energy of mixed systems (Zuend et al., 2008). This model enables the computation of vapor-liquid (VLE), liquid-liquid (LLE) and solid-liquid (SLE) equilibria within one framework. Focusing on atmospheric applications we considered eight different cations, five anions and a wide range of alcohols/polyols as organic compounds. With AIOMFAC, the activities of the components within an aqueous electrolyte solution are very well represented up to high ionic strength. We show that the semi-empirical middle-range parametrization of direct organic-inorganic interactions in alcohol-water-salt solutions enables accurate computations of vapor-liquid and liquid
Thermodynamic modeling using BINGO-ANTIDOTE: A new strategy to investigate metamorphic rocks
Lanari, Pierre; Duesterhoeft, Erik
2016-04-01
BINGO-ANTIDOTE is a new program, combing the achievements of the two petrological software packages XMAPTOOLS[1] and THERIAK-DOMINO[2]. XMAPTOOLS affords information about compositional zoning in mineral and local bulk composition of domains at the thin sections scale. THERIAK-DOMINO calculates equilibrium phase assemblages from given bulk rock composition, temperature T and pressure P. Primarily BINGO-ANTIDOTE can be described as an inverse THERIAK-DOMINO, because it uses the information provided by XMAPTOOLS to calculate the probable P-T equilibrium conditions of metamorphic rocks. Consequently, the introduced program combines the strengths of forward Gibbs free energy minimization models with the intuitive output of inverse thermobarometry models. In order to get "best" P-T equilibrium conditions of a metamorphic rock sample and thus estimating the degree of agreement between the observed and calculated mineral assemblage, it is critical to define a reliable scoring strategy. BINGO uses the THERIAKD ADD-ON[3] (Duesterhoeft and de Capitani, 2013) and is a flexible model scorer with 3+1 evaluation criteria. These criteria are the statistical agreement between the observed and calculated mineral-assemblage, -proportions (vol%) and -composition (mol). Additionally, a total likelihood, consisting of the first three criteria, allows the user an evaluation of the most probable equilibrium P-T condition. ANTIDOTE is an interactive user interface, displaying the 3+1 evaluation criteria as probability P-T-maps. It can be used with and without XMAPTOOLS. As a stand-alone program, the user is able to give the program macroscopic observations (i.e., mineral names and proportions), which ANTIDOTE converts to a readable BINGO input. In this manner, the use of BINGO-ANTIDOTE opens up thermodynamics to students and people with only a basic knowledge of phase diagrams and thermodynamic modeling techniques. This presentation introduces BINGO-ANTIDOTE and includes typical examples
Thermodynamic modeling of hydrogen storage capacity in Mg-Na alloys.
Abdessameud, S; Mezbahul-Islam, M; Medraj, M
2014-01-01
Thermodynamic modeling of the H-Mg-Na system is performed for the first time in this work in order to understand the phase relationships in this system. A new thermodynamic description of the stable NaMgH3 hydride is performed and the thermodynamic models for the H-Mg, Mg-Na, and H-Na systems are reassessed using the modified quasichemical model for the liquid phase. The thermodynamic properties of the ternary system are estimated from the models of the binary systems and the ternary compound using CALPHAD technique. The constructed database is successfully used to reproduce the pressure-composition isotherms for MgH2 + 10 wt.% NaH mixtures. Also, the pressure-temperature equilibrium diagram and reaction paths for the same composition are predicted at different temperatures and pressures. Even though it is proved that H-Mg-Na does not meet the DOE hydrogen storage requirements for onboard applications, the best working temperatures and pressures to benefit from its full catalytic role are given. Also, the present database can be used for thermodynamic assessments of higher order systems.
Thermodynamic Modeling of Hydrogen Storage Capacity in Mg-Na Alloys
Directory of Open Access Journals (Sweden)
S. Abdessameud
2014-01-01
Full Text Available Thermodynamic modeling of the H-Mg-Na system is performed for the first time in this work in order to understand the phase relationships in this system. A new thermodynamic description of the stable NaMgH3 hydride is performed and the thermodynamic models for the H-Mg, Mg-Na, and H-Na systems are reassessed using the modified quasichemical model for the liquid phase. The thermodynamic properties of the ternary system are estimated from the models of the binary systems and the ternary compound using CALPHAD technique. The constructed database is successfully used to reproduce the pressure-composition isotherms for MgH2 + 10 wt.% NaH mixtures. Also, the pressure-temperature equilibrium diagram and reaction paths for the same composition are predicted at different temperatures and pressures. Even though it is proved that H-Mg-Na does not meet the DOE hydrogen storage requirements for onboard applications, the best working temperatures and pressures to benefit from its full catalytic role are given. Also, the present database can be used for thermodynamic assessments of higher order systems.
Dutt, Arun K.
1990-03-01
Thermodynamic analysis of the reversible Selkov model (a simple kinetic model describing glycolytic oscillations) has been done by an entropy production technique of Prigogine and it is shown that only the autocatalytic step can destabilize the steady state in this model. It is derived that at thermodynamic equilibrium, the product δS δP is always a positive quantity which appears to be a Chatelier-like principle for local concentration fluctuation applicable to the autocatalytic step S ⇄ P of this model.
The european Trans-Tools transport model
Rooijen, T. van; Burgess, A.
2008-01-01
The paper presents the use of ArcGIS in the Transtools Transport Model, TRANS-TOOLS, created by an international consortium for the European Commission. The model describe passenger as well as freight transport in Europe with all medium and long distance modes (cars, vans, trucks, train, inland
The european Trans-Tools transport model
Rooijen, T. van; Burgess, A.
2008-01-01
The paper presents the use of ArcGIS in the Transtools Transport Model, TRANS-TOOLS, created by an international consortium for the European Commission. The model describe passenger as well as freight transport in Europe with all medium and long distance modes (cars, vans, trucks, train, inland wate
System level modelling with open source tools
DEFF Research Database (Denmark)
Jakobsen, Mikkel Koefoed; Madsen, Jan; Niaki, Seyed Hosein Attarzadeh;
, called ForSyDe. ForSyDe is available under the open Source approach, which allows small and medium enterprises (SME) to get easy access to advanced modeling capabilities and tools. We give an introduction to the design methodology through the system level modeling of a simple industrial use case, and we...
Coupled thermodynamic-dynamic semi-analytical model of free piston Stirling engines
Energy Technology Data Exchange (ETDEWEB)
Formosa, F., E-mail: fabien.formosa@univ-savoie.f [Laboratoire SYMME, Universite de Savoie, BP 80439, 74944 Annecy le Vieux Cedex (France)
2011-05-15
Research highlights: {yields} The free piston Stirling behaviour relies on its thermal and dynamic features. {yields} A global semi-analytical model for preliminary design is developed. {yields} The model compared with NASA-RE1000 experimental data shows good correlations. -- Abstract: The study of free piston Stirling engine (FPSE) requires both accurate thermodynamic and dynamic modelling to predict its performances. The steady state behaviour of the engine partly relies on non linear dissipative phenomena such as pressure drop loss within heat exchangers which is dependant on the temperature within the associated components. An analytical thermodynamic model which encompasses the effectiveness and the flaws of the heat exchangers and the regenerator has been previously developed and validated. A semi-analytical dynamic model of FPSE is developed and presented in this paper. The thermodynamic model is used to define the thermal variables that are used in the dynamic model which evaluates the kinematic results. Thus, a coupled iterative strategy has been used to perform a global simulation. The global modelling approach has been validated using the experimental data available from the NASA RE-1000 Stirling engine prototype. The resulting coupled thermodynamic-dynamic model using a standardized description of the engine allows efficient and realistic preliminary design of FPSE.
TOOL FORCE MODEL FOR DIAMOND TURNING
Institute of Scientific and Technical Information of China (English)
Wang Hongxiang; Sun Tao; Li Dan; Dong Shen
2004-01-01
A new tool force model to be presented is based upon process geometry and the characteristics of the force system,in which the forces acting on the tool rake face,the cutting edge rounding and the clearance face have been considered,and the size effect is accountable for the new model.It is desired that the model can be well applicable to conventional diamond turning and the model may be employed as a tool in the design of diamond tools.This approach is quite different from traditional investigations primarily based on empirical studies.As the depth of cut becomes the same order as the rounded cutting edge radius,sliding along the clearance face due to elastic recovery of workpiece material and plowing due to the rounded cutting edge may become important in micro-machining,the forces acting on the cutting edge rounding and the clearance face can not be neglected.For this reason,it is very important to understand the influence of some parameters on tool forces and develop a model of the relationship between them.
The Second Law of Thermodynamics in a Quantum Heat Engine Model
Zhang, Ting; Cai, Li-Feng; Chen, Ping-Xing; Li, Cheng-Zu
2006-03-01
The second law of thermodynamics has been proven by many facts in classical world. Is there any new property of it in quantum world? In this paper, we calculate the change of entropy in T.D. Kieu's model for quantum heat engine (QHE) and prove the broad validity of the second law of thermodynamics. It is shown that the entropy of the quantum heat engine neither decreases in a whole cycle, nor decreases in either stage of the cycle. The second law of thermodynamics still holds in this QHE model. Moreover, although the modified quantum heat engine is capable of extracting more work, its efficiency does not improve at all. It is neither beyond the efficiency of T.D. Kieu's initial model, nor greater than the reversible Carnot efficiency.
The Second Law of Thermodynamics in a Quantum Heat Engine Model
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
The second law of thermodynamics has been proven by many facts in classical world. Is there any new property of it in quantum world? In this paper, we calculate the change of entropy in T.D. Kieu's model for quantum heat engine (QHE) and prove the broad validity of the second law of thermodynamics. It is shown that the entropy of the quantum heat engine neither decreases in a whole cycle, nor decreases in either stage of the cycle. The second law of thermodynamics still holds in this QHE model. Moreover, although the modified quantum heat engine is capable of extracting more work, its efficiency does not improve at all. It is neither beyond the efficiency of T.D. Kieu's initial model, nor greater than the reversible Carnot efficiency.
Directory of Open Access Journals (Sweden)
Chellaboina Vijaysekhar
2005-01-01
Full Text Available We develop thermodynamic models for discrete-time large-scale dynamical systems. Specifically, using compartmental dynamical system theory, we develop energy flow models possessing energy conservation, energy equipartition, temperature equipartition, and entropy nonconservation principles for discrete-time, large-scale dynamical systems. Furthermore, we introduce a new and dual notion to entropy; namely, ectropy, as a measure of the tendency of a dynamical system to do useful work and grow more organized, and show that conservation of energy in an isolated thermodynamic system necessarily leads to nonconservation of ectropy and entropy. In addition, using the system ectropy as a Lyapunov function candidate, we show that our discrete-time, large-scale thermodynamic energy flow model has convergent trajectories to Lyapunov stable equilibria determined by the system initial subsystem energies.
Thermodynamic Modelling of Dolomite Behavior in Aqueous Media
Directory of Open Access Journals (Sweden)
Tadeusz Michałowski
2012-01-01
Full Text Available The compact thermodynamic approach to the systems containing calcium, magnesium, and carbonate species is referred to dissolution of dolomite, as an example of nonequilibrium ternary salt when introduced into aqueous media. The study of dolomite is based on all attainable physicochemical knowledge, involved in expressions for equilibrium constants, where the species of the system are interrelated. The species are also involved in charge and concentration balances, considered as constraints put on a closed system, separated from the environment by diathermal walls. The inferences are gained from calculations performed with use of an iterative computer program. The simulated quasistatic processes occurred under isothermal conditions, started at a preassumed pH0 value of the solution where dolomite was introduced, and are usually involved with formation of other solid phases. None simplifying assumptions in the calculations were made.
Thermodynamical modeling of viscous dissipation in magnetohydrodynamic ﬂow
Directory of Open Access Journals (Sweden)
Chandrasekar M.
2007-01-01
Full Text Available A genuine variational principle developed by Gyarmati, in the field of thermodynamics of irreversible processes unifying the theoretical requirements of technical, environmental and biological sciences is employed to study the effects of viscous dissipation and stress work on MHD forced convection flow adjacent to a non-isothermal wedge. The velocity and temperature distributions inside the boundary layer are considered as simple polynomial functions and the variational principle is formulated. The Euler-Lagrange equations are reduced to simple polynomial equations in terms of boundary layer thicknesses. The values of skin friction coefficient and the Nusselt number are presented for various values of wedge angle parameter m, wall temperature exponent 2m, magnetic parameter ξ, Prandtl number (Pr and Eckert number (Ec. The present results are compared with known available results and the comparison is found to be satisfactory and the present study establishes the fact that the accuracy is remarkable.
Revisiting the thermodynamic relations in AdS /CMT models
Hyun, Seungjoon; Park, Sang-A.; Yi, Sang-Heon
2017-03-01
Motivated by the recent unified approach to the Smarr-like relation of anti-de Sitter (AdS) planar black holes in conjunction with the quasilocal formalism on conserved charges, we revisit the quantum statistical and thermodynamic relations of hairy AdS planar black holes. By extending the previous results, we identify the hairy contribution in the bulk and show that the holographic computation can be improved so that it is consistent with the bulk computation. We argue that the first law can be retained in its universal form and that the relation between the on-shell renormalized Euclidean action and its free energy interpretation in gravity may also be undeformed even with the hairy contribution in hairy AdS black holes.
Thermodynamic modeling of the Eu–Te and Te–Yb systems
Energy Technology Data Exchange (ETDEWEB)
Ghamri, H., E-mail: ghamri.houda@hotmail.fr; Djaballah, Y.; Belgacem-Bouzida, A.
2015-09-15
Highlights: • The Eu–Te and Te–Yb binary systems were not previously thermodynamically assessed. • The Eu–Te and Te–Yb systems were assessed by using the CALPHAD technique. • A coherent set of thermodynamic parameters was obtained for both systems. • An agreement between the calculated results and experimental data was obtained for both systems. - Abstract: In this work, thermodynamic assessments of the Eu–Te and Te–Yb binary systems were carried out by using the CALculation of PHase Diagrams (CALPHAD) method based on the available experimental data including thermodynamic properties and phase equilibria. Reasonable models were constructed for all the phases of the two systems. The liquid phases were described by the substitutional solution model with the Redlich–Kister polynomial. The three intermetallic compounds, Eu{sub 4}Te{sub 7}, Eu{sub 3}Te{sub 7} and TeYb in the two systems, were treated as stoichiometric phases, while the non-stoichiometric phase (EuTe), which has an homogeneity range, was treated by a two-sublattice model following the schema: (Eu,Te){sub 0.5}(Te){sub 0.5}. A consistent set of thermodynamic parameters leading to reasonable agreement between the calculated results and experimental data was obtained.
Satoh, Katsuhiko
2013-08-28
The thermodynamic scaling of molecular dynamic properties of rotation and thermodynamic parameters in a nematic phase was investigated by a molecular dynamic simulation using the Gay-Berne potential. A master curve for the relaxation time of flip-flop motion was obtained using thermodynamic scaling, and the dynamic property could be solely expressed as a function of TV(γτ) , where T and V are the temperature and volume, respectively. The scaling parameter γτ was in excellent agreement with the thermodynamic parameter Γ, which is the logarithm of the slope of a line plotted for the temperature and volume at constant P2. This line was fairly linear, and as good as the line for p-azoxyanisole or using the highly ordered small cluster model. The equivalence relation between Γ and γ(τ) was compared with results obtained from the highly ordered small cluster model. The possibility of adapting the molecular model for the thermodynamic scaling of other dynamic rotational properties was also explored. The rotational diffusion constant and rotational viscosity coefficients, which were calculated using established theoretical and experimental expressions, were rescaled onto master curves with the same scaling parameters. The simulation illustrates the universal nature of the equivalence relation for liquid crystals.
The matrix model, a driven state variables approach to non-equilibrium thermodynamics
Jongschaap, R.J.J.
2001-01-01
One of the new approaches in non-equilibrium thermodynamics is the so-called matrix model of Jongschaap. In this paper some features of this model are discussed. We indicate the differences with the more common approach based upon internal variables and the more sophisticated Hamiltonian and GENERIC
Effects of quantum instantons on the thermodynamics of the CPN-1 model
Andersen, Jens O.; Boer, Daniel; Warringa, Harmen J.
2006-01-01
Using the 1/N expansion, we study the influence of quantum instantons on the thermodynamics of the CPN-1 model in 1+1 dimensions. We do this by calculating the pressure to next-to-leading order in 1/N, without quantum instanton contributions. The fact that the CP1 model is equivalent to the O(3) non
ms2: A molecular simulation tool for thermodynamic properties, new version release
Glass, Colin W; Rutkai, Gábor; Deublein, Stephan; Köster, Andreas; Carrión, Gabriela Guevara; Wafai, Amer; Horsch, Martin; Bernreuther, Martin F; Windmann, Thorsten; Hasse, Hans; Vrabec, Jadran
2015-01-01
A new version release (2.0) of the molecular simulation tool ms2 [S. Deublein et al., Comput. Phys. Commun. 182 (2011) 2350] is presented. Version 2.0 of ms2 features a hybrid parallelization based on MPI and OpenMP for molecular dynamics simulation to achieve higher scalability. Furthermore, the formalism by Lustig [R. Lustig, Mol. Phys. 110 (2012) 3041] is implemented, allowing for a systematic sampling of Massieu potential derivatives in a single simulation run. Moreover, the Green-Kubo formalism is extended for the sampling of the electric conductivity and the residence time. To remove the restriction of the preceding version to electro-neutral molecules, Ewald summation is implemented to consider ionic long range interactions. Finally, the sampling of the radial distribution function is added.
Vapor-liquid equilibrium thermodynamics of N2 + CH4 - Model and Titan applications
Thompson, W. R.; Zollweg, John A.; Gabis, David H.
1992-01-01
A thermodynamic model is presented for vapor-liquid equilibrium in the N2 + CH4 system, which is implicated in calculations of the Titan tropospheric clouds' vapor-liquid equilibrium thermodynamics. This model imposes constraints on the consistency of experimental equilibrium data, and embodies temperature effects by encompassing enthalpy data; it readily calculates the saturation criteria, condensate composition, and latent heat for a given pressure-temperature profile of the Titan atmosphere. The N2 content of condensate is about half of that computed from Raoult's law, and about 30 percent greater than that computed from Henry's law.
Zinnecker, Alicia M.; Chapman, Jeffryes W.; Lavelle, Thomas M.; Litt, Johathan S.
2014-01-01
The Toolbox for Modeling and Analysis of Thermodynamic Systems (T-MATS) is a tool that has been developed to allow a user to build custom models of systems governed by thermodynamic principles using a template to model each basic process. Validation of this tool in an engine model application was performed through reconstruction of the Commercial Modular Aero-Propulsion System Simulation (C-MAPSS) (v2) using the building blocks from the T-MATS (v1) library. In order to match the two engine models, it was necessary to address differences in several assumptions made in the two modeling approaches. After these modifications were made, validation of the engine model continued by integrating both a steady-state and dynamic iterative solver with the engine plant and comparing results from steady-state and transient simulation of the T-MATS and C-MAPSS models. The results show that the T-MATS engine model was accurate within 3 of the C-MAPSS model, with inaccuracy attributed to the increased dimension of the iterative solver solution space required by the engine model constructed using the T-MATS library. This demonstrates that, given an understanding of the modeling assumptions made in T-MATS and a baseline model, the T-MATS tool provides a viable option for constructing a computational model of a twin-spool turbofan engine that may be used in simulation studies.
Zinnecker, Alicia M.; Chapman, Jeffryes W.; Lavelle, Thomas M.; Litt, Jonathan S.
2014-01-01
The Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS) is a tool that has been developed to allow a user to build custom models of systems governed by thermodynamic principles using a template to model each basic process. Validation of this tool in an engine model application was performed through reconstruction of the Commercial Modular Aero-Propulsion System Simulation (C-MAPSS) (v2) using the building blocks from the T-MATS (v1) library. In order to match the two engine models, it was necessary to address differences in several assumptions made in the two modeling approaches. After these modifications were made, validation of the engine model continued by integrating both a steady-state and dynamic iterative solver with the engine plant and comparing results from steady-state and transient simulation of the T-MATS and C-MAPSS models. The results show that the T-MATS engine model was accurate within 3% of the C-MAPSS model, with inaccuracy attributed to the increased dimension of the iterative solver solution space required by the engine model constructed using the T-MATS library. This demonstrates that, given an understanding of the modeling assumptions made in T-MATS and a baseline model, the T-MATS tool provides a viable option for constructing a computational model of a twin-spool turbofan engine that may be used in simulation studies.
Directory of Open Access Journals (Sweden)
Mohamad Javad Kamali
2015-01-01
Full Text Available Thermodynamic modeling of surface tension of different electrolyte systems in presence of gas phase is studied. Using the solid-liquid equilibrium, Langmuir gas-solid adsorption, and ENRTL activity coefficient model, the surface tension of electrolyte solutions is calculated. The new model has two adjustable parameters which could be determined by fitting the experimental surface tension of binary aqueous electrolyte solution in single temperature. Then the values of surface tension for other temperatures in binary and ternary system of aqueous electrolyte solution are predicted. The average absolute deviations for calculation of surface tension of binary and mixed electrolyte systems by new model are 1.98 and 1.70%, respectively.
Chapman, Jeffryes W.; Lavelle, Thomas M.; May, Ryan D.; Litt, Jonathan S.; Guo, Ten-Huei (OA)
2014-01-01
A simulation toolbox has been developed for the creation of both steady-state and dynamic thermodynamic software models. This presentation describes the Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS), which combines generic thermodynamic and controls modeling libraries with a numerical iterative solver to create a framework for the development of thermodynamic system simulations, such as gas turbine engines. The objective of this presentation is to present an overview of T-MATS, the theory used in the creation of the module sets, and a possible propulsion simulation architecture.
He I lines in B stars - Comparison of non-local thermodynamic equilibrium models with observations
Heasley, J. N.; Timothy, J. G.; Wolff, S. C.
1982-01-01
Profiles of He gamma-gamma 4026, 4387, 4471, 4713, 5876, and 6678 have been obtained in 17 stars of spectral type B0-B5. Parameters of the nonlocal thermodynamic equilibrium models appropriate to each star are determined from the Stromgren index and fits to H-alpha line profiles. These parameters yield generally good fits to the observed He I line profiles, with the best fits being found for the blue He I lines where departures from local thermodynamic equilibrium are relatively small. For the two red lines it is found that, in the early B stars and in stars with log g less than 3.5, both lines are systematically stronger than predicted by the nonlocal thermodynamic equilibrium models.
Thermodynamic modeling of the Na-X (X = Si, Ag, Cu, Cr systems
Directory of Open Access Journals (Sweden)
Hao D.
2012-01-01
Full Text Available The Na-X (X = Si, Ag, Cu, Cr systems have been critically reviewed and modeled by means of the CALPHAD approach. The two compounds, NaSi and Ag2Na, are treated as stoichiometric ones. By means of first-principles calculations, the enthalpies of formation at 0 K for the LT-NaSi (low temperature form of NaSi and Ag2Na have been computed to be -5210 and -29821.8 Jmol-1, respectively, with the desire to assist thermodynamic modeling. One set of self-consistent thermodynamic parameters is obtained for each of these binary systems. Comparisons between calculated and measured phase diagrams show that most of the experimental information can be satisfactorily accounted for by the present thermodynamic descriptions.
Institute of Scientific and Technical Information of China (English)
陈建彬; 吕小强
2011-01-01
Aiming at the fact that the energy and mass exchange phenomena exist between barrel and gas-operated device of the automatic weapon, for describing its interior ballistics and dynamic characteristics of the gas-operated device accurately, a new variable-mass thermodynamics model is built. It is used to calculate the automatic mechanism velocity of a certain automatic weapon, the calculation results coincide with the experimental results better, and thus the model is validated. The influences of structure parameters on gas-operated device＇ s dynamic characteristics are discussed. It shows that the model is valuable for design and accurate performance prediction of gas-operated automatic weapon.
HIGH TEMPERATURE HIGH PRESSURE THERMODYNAMIC MEASUREMENTS FOR COAL MODEL COMPOUNDS
Energy Technology Data Exchange (ETDEWEB)
Vinayak N. Kabadi
2000-05-01
The flow VLE apparatus designed and built for a previous project was upgraded and recalibrated for data measurements for this project. The modifications include better and more accurate sampling technique, addition of a digital recorder to monitor temperature and pressure inside the VLE cell, and a new technique for remote sensing of the liquid level in the cell. VLE data measurements for three binary systems, tetralin-quinoline, benzene--ethylbenzene and ethylbenzene--quinoline, have been completed. The temperature ranges of data measurements were 325 C to 370 C for the first system, 180 C to 300 C for the second system, and 225 C to 380 C for the third system. The smoothed data were found to be fairly well behaved when subjected to thermodynamic consistency tests. SETARAM C-80 calorimeter was used for incremental enthalpy and heat capacity measurements for benzene--ethylbenzene binary liquid mixtures. Data were measured from 30 C to 285 C for liquid mixtures covering the entire composition range. An apparatus has been designed for simultaneous measurement of excess volume and incremental enthalpy of liquid mixtures at temperatures from 30 C to 300 C. The apparatus has been tested and is ready for data measurements. A flow apparatus for measurement of heat of mixing of liquid mixtures at high temperatures has also been designed, and is currently being tested and calibrated.
A review of electricity market modelling tools
Directory of Open Access Journals (Sweden)
Sandra Milena Londoño Hernández
2010-05-01
Full Text Available Deregulating electricity markets around the world in the search for efficiency has introduced competition into the electricity marke- ting and generation business. Studying interactions amongst the participants has thus acquired great importance for regulators and market participants for analysing market evolution and suitably defining their bidding strategies. Different tools have thereof- re been used for modelling competitive electricity markets during the last few years. This paper presents an analytical review of the bibliography found regarding this subject; it also presents the most used tools along with their advantages and disadvantages. Such analysis was done by comparing the models used, identifying the main market characteristics such as market structure, bid structure and kind of bidding. This analysis concluded that the kind of tool to be used mainly depends on a particular study’s goal and scope.
Wang, W B; Cao, Z M; Hu, R F
2013-01-01
A model based on a thermodynamic approach is proposed for predicting the dynamics of communicable epidemics in a city, when the epidemic is governed by controlling efforts of multiple scales so that an entropy is associated with the system. All the epidemic details are factored into a single parameter that is determined by maximizing the rate of entropy production. Despite the simplicity of the final model, it predicts the number of hospitalized cases with a reasonable accuracy, using the data of SARS of the year 2003, once the inflexion point characterizing the effect of multiple controlling efforts is known. This model is supposed to be of potential usefulness since epidemics such as avian influenza like H7H9 in China this year have the risk to become communicable among human beings.
HYDROLOGICAL PROCESSES MODELLING USING ADVANCED HYDROINFORMATIC TOOLS
Directory of Open Access Journals (Sweden)
BEILICCI ERIKA
2014-03-01
Full Text Available The water has an essential role in the functioning of ecosystems by integrating the complex physical, chemical, and biological processes that sustain life. Water is a key factor in determining the productivity of ecosystems, biodiversity and species composition. Water is also essential for humanity: water supply systems for population, agriculture, fisheries, industries, and hydroelectric power depend on water supplies. The modelling of hydrological processes is an important activity for water resources management, especially now, when the climate change is one of the major challenges of our century, with strong influence on hydrological processes dynamics. Climate change and needs for more knowledge in water resources require the use of advanced hydroinformatic tools in hydrological processes modelling. The rationale and purpose of advanced hydroinformatic tools is to develop a new relationship between the stakeholders and the users and suppliers of the systems: to offer the basis (systems which supply useable results, the validity of which cannot be put in reasonable doubt by any of the stakeholders involved. For a successful modelling of hydrological processes also need specialists well trained and able to use advanced hydro-informatics tools. Results of modelling can be a useful tool for decision makers to taking efficient measures in social, economical and ecological domain regarding water resources, for an integrated water resources management.
Study on swelling model and thermodynamic structure of native konjac glucomannan
Institute of Scientific and Technical Information of China (English)
Long LI; Hui RUAN; Liu-liu MA; Wei WANG; Ping ZHOU; Guo-qing HE
2009-01-01
We investigated the higher structure of konjac glucomannan (KGM) in the amorphous state and solution using a laser particle size analyzer and a water activity meter. The results show that the thermodynamic structures of native KGM were pri-marily composed of the lamella structure units, which involve both granular crystalline and amorphous regions, and that the connection zones of such units contained both loose and tight aggregation regions. The value of surface tension (σ) of native KGM,resting with the density of its hydroxyl groups' self-association, Was an important parameter to analyze the higher structures of native KGM in the thermodynamic swelling model of native KGM.
An analytical model for resistivity tools
Energy Technology Data Exchange (ETDEWEB)
Hovgaard, J.
1991-04-01
An analytical model for resistivity tools is developed. It takes into account the effect of the borehole and the actual shape of the electrodes. The model is two-dimensional, i.e. the model does not deal with eccentricity. The electrical potential around a current source satisfies Poisson`s equation. The method used here to solve Poisson`s equation is the expansion fo the potential function in terms of a complete set of functions involving one of the coordinates with coefficients which are undetermined functions of the other coordinate. Numerical examples of the use of the model are presented. The results are compared with results given in the literature. (au).
Thermodynamic Modeling of Zinc Speciation in Electric Arc Furnace Dust
Pickles, Chris A.
2011-04-01
The remelting of automobile scrap, containing galvanized steel, in an electric arc furnace (EAF) results in the generation of a dust, which contains considerable amounts of zinc and other metals. Typically, the amount of zinc is of significant commercial value, but the recovery of this metal can be hindered by the varied speciation of zinc. The majority of the zinc exists as zincite (ZnO) and zinc ferrite (ZnFe2O4) or ferritic spinels ((Zn x Mn y Fe1-x-y )Fe2O4), but other zinccontaining species such as zinc chloride, zinc hydroxide chlorides, hydrated zinc sulphates and zinc silicates have also been identified. There is a scarcity of research literature on the thermodynamic aspects of the formation of these zinc-containing species, in particular, the minor zinc-containing species. Therefore, in this study, the equilibrium module of HSC Chemistry® 6.1 was utilized to calculate the types and the amounts of the zinc-containing species. The variables studied were: the gas composition, the temperature and the dust composition. At high temperatures, zincite forms via the reaction of zinc vapour with oxygen gas and the zinc-manganese ferrites form as a result of the reaction of iron-manganese particles with zinc vapour and oxygen. At intermediate temperatures, zinc sulphates are produced through the reaction of zinc oxide and sulphur dioxide gas. As room temperature is approached, zinc chlorides and fluorides form by the reaction of zinc oxide with hydrogen chloride and hydrogen fluoride gases, respectively. Zinc silicate likely forms via the high temperature reaction of zinc vapour and oxygen with silica. In the presence of excess water and as room temperature is approached, the zinc sulphates, chlorides and fluorides can become hydrated.
Stability and Thermodynamic Restrictions for a Dual-Phase-Lag Thermal Model
Fabrizio, Mauro; Lazzari, Barbara; Tibullo, Vincenzo
2017-06-01
In this paper, the seeming inconsistency highlighted by Fabrizio and Lazzari (Stability and second law of thermodynamics in dual-phase-lag heat conduction, Int. J. Heat Mass Transfer 74 (2014), 484-489) and Quintanilla and Racke (A note on stability of dual-phase-lag heat conduction, Int. J. Heat Mass Transfer 49 (2007), 1209-1213) for a thermoelastic material, between the thermodynamic restrictions and the stability conditions is studied. Actually, we show as these results are due to the use of different formulations of the thermodynamic principles, which are not always equivalent. So that, we prove by the model considered in the paper that these two formulations do not lead to the same restrictions on the constitutive equations. This analysis allowed us to restore the compatibility by an appropriate and wide representation of the Second Law.
A Thermodynamic Model for Square-well Chain Fluid: Theory and Monte Carlo Simulation
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
A thermodynamic model for the freely jointed square-well chain fluids was developed based on the thermodynamic perturbation theory of Barker-Henderson, Zhang and Wertheim. In this derivation Zhang's expressions for square-well monomers improved from Barker-Henderson compressibility approximation were adopted as the reference fluid, and Wertheim＇s polymerization method was used to obtain the free energy term due to the bond connectivity. An analytic expression for the Helmholtz free energy of the square-well chain fluids was obtained. The expression without adjustable parameters leads to the thermodynamic consistent predictions of the compressibility factors, residual internal energy and constant-volume heat capacity for dimer,4-mer, 8-mer and 16-mer square-well fluids. The results are in good agreement with the Monte Carlo simulation. To obtain the MC data of residual internal energy and the constant-volume heat capacity needed, NVT MC simulations were performed for these square-well chain fluids.
Thermodynamic and mechanical properties of curved interfaces : A discussion of models
Oversteegen, S.M.
2000-01-01
Although relatively much is known about the physics of curved interfaces, several models for these kind of systems seem conflicting or internally inconsistent. It is the aim of this thesis to derive a rigorous framework of thermodynamic and mechanical expressions and study their relation to previous
Huang, M.; Rivera-Diaz-del-Castillo, P.E.J.; Bouaziz, O.; Van der Zwaag, S.
2009-01-01
Based on the theory of irreversible thermodynamics, the present work proposes a dislocation-based model to describe the plastic deformation of FCC metals over wide ranges of strain rates. The stress-strain behaviour and the evolution of the average dislocation density are derived. It is found that t
Particle Model for Work, Heat, and the Energy of a Thermodynamic System
DeVoe, Howard
2007-01-01
A model of a thermodynamic system is described in which particles (representing atoms) interact with one another, the surroundings, and the earth's gravitational field according to the principles of classical mechanics. The system's energy "E" and internal energy "U" are defined. The importance is emphasized of the dependence of energy and work on…
The simplified Hubbard model in one and two dimensions. Thermodynamic and dynamic properties
Vries, Pedro de; Michielsen, Kristel; Raedt, Hans De
1993-01-01
Thermodynamic and dynamic properties of the one and two-dimensional simplified Hubbard model are studied. At zero temperature and half filling, no metal-insulator transition occurs for nonzero coupling U and the system is an antiferromagnetic insulator. The behavior of the gap in the single-particle
THE SIMPLIFIED HUBBARD-MODEL IN ONE AND 2 DIMENSIONS - THERMODYNAMIC AND DYNAMIC PROPERTIES
DEVRIES, P; MICHIELSEN, K; DERAEDT, H
1993-01-01
Thermodynamic and dynamic properties of the one and two-dimensional simplified Hubbard model are studied. At zero temperature and half filling, no metal-insulator transition occurs for nonzero coupling U and the system is an antiferromagnetic insulator. The behavior of the gap in the single-particle
Thermodynamic and Process Modelling of Gas Hydrate Systems in CO2 Capture Processes
DEFF Research Database (Denmark)
Herslund, Peter Jørgensen
A novel gas separation technique based on gas hydrate formation (solid precipitation) is investigated by means of thermodynamic modeling and experimental investigations. This process has previously been proposed for application in post-combustion carbon dioxide capture from power station flue gas...
Modeling thermodynamics of Fe-N phases; characterisation of e-Fe2N1-z
DEFF Research Database (Denmark)
Pekelharing, M.I.; Böttger, A.; Somers, Marcel A.J.
1999-01-01
In order to arrive at modeling the thermodynamics of Fe-N phases, including long-range (LRO) and short-range ordering (SRO) of the N atoms, it is important to understand the role of N interstitially dissolved in an Fe-host lattice. The crystal structure of -Fe2N1-z consists of an h.c.p. iron...
Network thermodynamic curation of human and yeast genome-scale metabolic models.
Martínez, Verónica S; Quek, Lake-Ee; Nielsen, Lars K
2014-07-15
Genome-scale models are used for an ever-widening range of applications. Although there has been much focus on specifying the stoichiometric matrix, the predictive power of genome-scale models equally depends on reaction directions. Two-thirds of reactions in the two eukaryotic reconstructions Homo sapiens Recon 1 and Yeast 5 are specified as irreversible. However, these specifications are mainly based on biochemical textbooks or on their similarity to other organisms and are rarely underpinned by detailed thermodynamic analysis. In this study, a to our knowledge new workflow combining network-embedded thermodynamic and flux variability analysis was used to evaluate existing irreversibility constraints in Recon 1 and Yeast 5 and to identify new ones. A total of 27 and 16 new irreversible reactions were identified in Recon 1 and Yeast 5, respectively, whereas only four reactions were found with directions incorrectly specified against thermodynamics (three in Yeast 5 and one in Recon 1). The workflow further identified for both models several isolated internal loops that require further curation. The framework also highlighted the need for substrate channeling (in human) and ATP hydrolysis (in yeast) for the essential reaction catalyzed by phosphoribosylaminoimidazole carboxylase in purine metabolism. Finally, the framework highlighted differences in proline metabolism between yeast (cytosolic anabolism and mitochondrial catabolism) and humans (exclusively mitochondrial metabolism). We conclude that network-embedded thermodynamics facilitates the specification and validation of irreversibility constraints in compartmentalized metabolic models, at the same time providing further insight into network properties.
Thermodynamic and mechanical properties of curved interfaces : a discussion of models
Oversteegen, M.
2000-01-01
Although relatively much is known about the physics of curved interfaces, several models for these kind of systems seem conflicting or internally inconsistent. It is the aim of this thesis to derive a rigorous framework of thermodynamic and mechanical expressions and study their relation to
Induction generator models in dynamic simulation tools
DEFF Research Database (Denmark)
Knudsen, Hans; Akhmatov, Vladislav
1999-01-01
. It is found to be possible to include a transient model in dynamic stability tools and, then, obtain correct results also in dynamic tools. The representation of the rotating system influences on the voltage recovery shape which is an important observation in case of windmills, where a heavy mill is connected......For AC network with large amount of induction generators (windmills) the paper demonstrates a significant discrepancy in the simulated voltage recovery after fault in weak networks when comparing dynamic and transient stability descriptions and the reasons of discrepancies are explained...
Ben-Naim, Arieh
2017-01-01
This textbook introduces thermodynamics with a modern approach, starting from four fundamental physical facts (the atomic nature of matter, the indistinguishability of atoms and molecules of the same species, the uncertainty principle, and the existence of equilibrium states) and analyzing the behavior of complex systems with the tools of information theory, in particular with Shannon's measure of information (or SMI), which can be defined on any probability distribution. SMI is defined and its properties and time evolution are illustrated, and it is shown that the entropy is a particular type of SMI, i.e. the SMI related to the phase-space distribution for a macroscopic system at equilibrium. The connection to SMI allows the reader to understand what entropy is and why isolated systems follow the Second Law of Thermodynamics. The Second Llaw is also formulated for other systems, not thermally isolated and even open with respect to the transfer of particles. All the fundamental aspects of thermodynamics are d...
Fontenete, Sílvia; Guimarães, Nuno; Wengel, Jesper; Azevedo, Nuno Filipe
2016-01-01
The thermodynamics and kinetics of DNA hybridization, i.e. the process of self-assembly of one, two or more complementary nucleic acid strands, has been studied for many years. The appearance of the nearest-neighbor model led to several theoretical and experimental papers on DNA thermodynamics that provide reasonably accurate thermodynamic information on nucleic acid duplexes and allow estimation of the melting temperature. Because there are no thermodynamic models specifically developed to predict the hybridization temperature of a probe used in a fluorescence in situ hybridization (FISH) procedure, the melting temperature is used as a reference, together with corrections for certain compounds that are used during FISH. However, the quantitative relation between melting and experimental FISH temperatures is poorly described. In this review, various models used to predict the melting temperature for rRNA targets, for DNA oligonucleotides and for nucleic acid mimics (chemically modified oligonucleotides), will be addressed in detail, together with a critical assessment of how this information should be used in FISH.
Thermodynamic Model for Updraft Gasifier with External Recirculation of Pyrolysis Gas
Directory of Open Access Journals (Sweden)
Fajri Vidian
2016-01-01
Full Text Available Most of the thermodynamic modeling of gasification for updraft gasifier uses one process of decomposition (decomposition of fuel. In the present study, a thermodynamic model which uses two processes of decomposition (decomposition of fuel and char is used. The model is implemented in modification of updraft gasifier with external recirculation of pyrolysis gas to the combustion zone and the gas flowing out from the side stream (reduction zone in the updraft gasifier. The goal of the model obtains the influences of amount of recirculation pyrolysis gas fraction to combustion zone on combustible gas and tar. The significant results of modification updraft are that the increases amount of recirculation of pyrolysis gas will increase the composition of H2 and reduce the composition of tar; then the composition of CO and CH4 is dependent on equivalence ratio. The results of the model for combustible gas composition are compared with previous study.
Animal models: an important tool in mycology.
Capilla, Javier; Clemons, Karl V; Stevens, David A
2007-12-01
Animal models of fungal infections are, and will remain, a key tool in the advancement of the medical mycology. Many different types of animal models of fungal infection have been developed, with murine models the most frequently used, for studies of pathogenesis, virulence, immunology, diagnosis, and therapy. The ability to control numerous variables in performing the model allows us to mimic human disease states and quantitatively monitor the course of the disease. However, no single model can answer all questions and different animal species or different routes of infection can show somewhat different results. Thus, the choice of which animal model to use must be made carefully, addressing issues of the type of human disease to mimic, the parameters to follow and collection of the appropriate data to answer those questions being asked. This review addresses a variety of uses for animal models in medical mycology. It focuses on the most clinically important diseases affecting humans and cites various examples of the different types of studies that have been performed. Overall, animal models of fungal infection will continue to be valuable tools in addressing questions concerning fungal infections and contribute to our deeper understanding of how these infections occur, progress and can be controlled and eliminated.
Concepts, Challenges and Successes in Modeling Thermodynamics of Metabolism
Directory of Open Access Journals (Sweden)
William R. Cannon
2014-11-01
Full Text Available The modeling of the chemical reactions involved in metabolism is a daunting task. Ideally, the modeling of metabolism would use kinetic simulations, but these simulations require knowledge of the thousands of rate constants involved in the reactions. The measurement of rate constants is very labor intensive, and hence rate constants for most enzymatic reactions are not available. Consequently, flux-based approaches have been the methods of choice because they do not require the use of the rate constants of the law of mass action. However, this convenience also limits the predictive power of flux-based approaches in that the law of mass action is not used directly, making it very difficult to predict metabolite levels or energy requirements of pathways.An alternative to both of these approaches is to model metabolism using simulations of states rather than simulations of reactions, in which the state is defined as the set of all metabolite counts or concentrations. While kinetic simulations model reactions based on the likelihood of the reaction derived from the law of mass action, states are modeled based on likelihood ratios of mass action. Both approaches provide information on the energy requirements of metabolic reactions and pathways. However, modeling states rather than reactions has the advantage that the parameters needed to model states (chemical potentials are much easier to determine than the parameters needed to model reactions (rate constants. Herein we discuss recent results, assumptions and issues in using simulations of state to model metabolism.
Choukroun, M.
2010-12-01
pure water, and of more complex chemical systems relevant to icy moons (sulfate salts, ammonia, volatiles). This presentation will review phases of interest, their physical properties, and their influence on the geophysical behavior of icy satellites. Then the focus will shift toward thermodynamic tools (equations of state, thermodynamic models), which can provide the inputs required by geophysical models. The specific case of the modeling of the water and water-ammonia phase diagrams will be presented,8,9 along with its planetary implications, and anticipated developments to address the chemical complexity of icy satellites. The author acknowledges support from a NASA Postdoctoral Program Fellowship, administered by Oak Ridge Associated Universities. This work has been conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. Government sponsorship acknowledged. References : 1Greeley et al., Icarus, 1998. 2McCord et al., J. Geophys. Res., 1999. 3Porco et al., Science, 2006. 4Waite et al., Nature, 2009. 5Toon et al., Icarus 1988. 6Sohl et al., Icarus 2002. 7Tobie et al., Icarus, 2005. 8Choukroun and Grasset, J. Chem. Phys, 2007. 9Choukroun and Grasset, J. Chem. Phys., in press.
Cheng, Hong-Bang; Kumar, Mathava; Lin, Jih-Gaw
2007-01-01
Nernst equation has been directly used to formulate the oxidation reduction potential (ORP) of reversible thermodynamic conditions but applied to irreversible conditions after several assumptions and/or modifications. However, the assumptions are sometimes inappropriate in the quantification of ORP in nonequilibrium system. We propose a linear nonequilibrium thermodynamic model, called microbial related reduction and oxidation reaction (MIRROR Model No. 1) for the interpretation of ORP in biological process. The ORP was related to the affinities of catabolism and anabolism. The energy expenditure of catabolism and anabolism was directly proportional to overpotential (η), straight coefficient of electrode (LEE), and degree of coupling between catabolism and ORP electrode, respectively. Finally, the limitations of MIRROR Model No. 1 were discussed for expanding the applicability of the model. PMID:17496027
Reščič, J.; Kalyuzhnyi, Y. V.; Cummings, P. T.
2016-10-01
The approach developed earlier to describe the dimerizing shielded attractive shell (SAS) primitive model of chemical association due to Cummings and Stell is generalized and extended to include a description of a polymerizing SAS model. Our extension is based on the combination of the resummed thermodynamic perturbation theory for central force (RTPT-CF) associating potential and self consistent scheme, which takes into account the changes in the system free volume due to association. Theoretical results for thermodynamical properties of the model at different bonding length, density and temperature are compared against newly generated computer simulation results. The theory gives very accurate predictions for the model with bonding length L * from the range 0 < L * < 0.6 at all values of the density and temperature studied, including the limit of infinitely large temperature.
Thermodynamic Modeling of Sulfide Capacity of Na2O-Containing Oxide Melts
Moosavi-Khoonsari, Elmira; Jung, In-Ho
2016-10-01
Thermodynamic modeling of the sulfide dissolution in the Na2O-FetO-CaO-MgO-MnO-Al2O3-SiO2 multicomponent slags was performed to investigate the desulfurization of hot metal using Na2O-containing fluxes. The dissolution behavior of sulfur in the melts was modeled using the modified quasi-chemical model in the quadruplet approximation. This model can take into account the short-range ordering and the reciprocal exchange reaction of cations and anions in oxy-sulfide slags. Experimental sulfide capacity data were well predicted from the model with only three model parameters.
A tool box for implementing supersymmetric models
Staub, Florian; Ohl, Thorsten; Porod, Werner; Speckner, Christian
2012-10-01
We present a framework for performing a comprehensive analysis of a large class of supersymmetric models, including spectrum calculation, dark matter studies and collider phenomenology. To this end, the respective model is defined in an easy and straightforward way using the Mathematica package SARAH. SARAH then generates model files for CalcHep which can be used with micrOMEGAs as well as model files for WHIZARD and O'Mega. In addition, Fortran source code for SPheno is created which facilitates the determination of the particle spectrum using two-loop renormalization group equations and one-loop corrections to the masses. As an additional feature, the generated SPheno code can write out input files suitable for use with HiggsBounds to apply bounds coming from the Higgs searches to the model. Combining all programs provides a closed chain from model building to phenomenology. Program summary Program title: SUSY Phenomenology toolbox. Catalog identifier: AEMN_v1_0. Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEMN_v1_0.html. Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland. Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html. No. of lines in distributed program, including test data, etc.: 140206. No. of bytes in distributed program, including test data, etc.: 1319681. Distribution format: tar.gz. Programming language: Autoconf, Mathematica. Computer: PC running Linux, Mac. Operating system: Linux, Mac OS. Classification: 11.6. Nature of problem: Comprehensive studies of supersymmetric models beyond the MSSM is considerably complicated by the number of different tasks that have to be accomplished, including the calculation of the mass spectrum and the implementation of the model into tools for performing collider studies, calculating the dark matter density and checking the compatibility with existing collider bounds (in particular, from the Higgs searches). Solution method: The
Thermodynamically consistent mesoscopic fluid particle models for a van der Waals fluid
Serrano, Mar; Español, Pep
2000-01-01
The GENERIC structure allows for a unified treatment of different discrete models of hydrodynamics. We first propose a finite volume Lagrangian discretization of the continuum equations of hydrodynamics through the Voronoi tessellation. We then show that a slight modification of these discrete equations has the GENERIC structure. The GENERIC structure ensures thermodynamic consistency and allows for the introduction of correct thermal noise. In this way, we obtain a consistent discrete model ...
Thermodynamics of the BMN matrix model at strong coupling
Costa, Miguel S.; Greenspan, Lauren; Penedones, João; Santos, Jorge E.
2015-03-01
We construct the black hole geometry dual to the deconfined phase of the BMN matrix model at strong 't Hooft coupling. We approach this solution from the limit of large temperature where it is approximately that of the non-extremal D0-brane geometry with a spherical S 8 horizon. This geometry preserves the SO(9) symmetry of the matrix model trivial vacuum. As the temperature decreases the horizon becomes deformed and breaks the SO(9) to the SO(6) × SO(3) symmetry of the matrix model. When the black hole free energy crosses zero the system undergoes a phase transition to the confined phase described by a Lin-Maldacena geometry. We determine this critical temperature, whose computation is also within reach of Monte Carlo simulations of the matrix model.
Thermodynamics of the BMN matrix model at strong coupling
Costa, Miguel S; Penedones, Joao; Santos, Jorge
2014-01-01
We construct the black hole geometry dual to the deconfined phase of the BMN matrix model at strong 't Hooft coupling. We approach this solution from the limit of large temperature where it is approximately that of the non-extremal D0-brane geometry with a spherical $S^8$ horizon. This geometry preserves the $SO(9)$ symmetry of the matrix model trivial vacuum. As the temperature decreases the horizon becomes deformed and breaks the $SO(9)$ to the $SO(6)\\times SO(3)$ symmetry of the matrix model. When the black hole free energy crosses zero the system undergoes a phase transition to the confined phase described by a Lin-Maldacena geometry. We determine this critical temperature, whose computation is also within reach of Monte Carlo simulations of the matrix model.
Modeling the Thermosphere as a Driven-Dissipative Thermodynamic System
2013-03-01
Schoendorf, K. D., Siebert, K. D., et al. “Hill Model of Transpolar Potential Saturation: Comparison with MHD Simulation,” Journal of Geophysical...March and 1 December, 2009, where the risk of collision with debris has forced the crew of the International Space Station to take emergency actions to...Solomon, S. C. “A Model of Nitric Oxide in the Lower Thermosphere,” Journal of Geophysical Research, 107: 1205 (2002). Borovsky, J. E., and Denton, M
Xia, Ke; Shen, Guang-Bin; Zhu, Xiao-Qing
2015-06-14
32 F420 coenzyme models with alkylation of the three different N atoms (N1, N3 and N10) in the core structure (XFH(-)) were designed and synthesized and the thermodynamic driving forces (defined in terms of the molar enthalpy changes or the standard redox potentials in this work) of the 32 XFH(-) releasing hydride ions, hydrogen atoms and electrons, the thermodynamic driving forces of the 32 XFH˙ releasing protons and hydrogen atoms and the thermodynamic driving forces of XF(-)˙ releasing electrons in acetonitrile were determined using titration calorimetry and electrochemical methods. The effects of the methyl group at N1, N3 and N10 and a negative charge on N1 and N10 atoms on the six thermodynamic driving forces of the F420 coenzyme models and their related reaction intermediates were examined; the results show that seating arrangements of the methyl group and the negative charge have remarkably different effects on the thermodynamic properties of the F420 coenzyme models and their related reaction intermediates. The effects of the substituents at C7 and C8 on the six thermodynamic driving forces of the F420 coenzyme models and their related reaction intermediates were also examined; the results show that the substituents at C7 and C8 have good Hammett linear free energy relationships with the six thermodynamic parameters. Meanwhile, a reasonable determination of possible reactions between members of the F420 family and NADH family in vivo was given according to a thermodynamic analysis platform constructed using the elementary step thermodynamic parameter of F420 coenzyme model 2FH(-) and NADH model MNAH releasing hydride ions in acetonitrile. The information disclosed in this work can not only fill a gap in the chemical thermodynamics of F420 coenzyme models as a class of very important organic sources of electrons, hydride ions, hydrogen atoms and protons, but also strongly promote the fast development of the chemistry and applications of F420 coenzyme.
Computational models with thermodynamic and composition features improve siRNA design
Directory of Open Access Journals (Sweden)
Ogurtsov Aleksey Y
2006-02-01
Full Text Available Abstract Background Small interfering RNAs (siRNAs have become an important tool in cell and molecular biology. Reliable design of siRNA molecules is essential for the needs of large functional genomics projects. Results To improve the design of efficient siRNA molecules, we performed a comparative, thermodynamic and correlation analysis on a heterogeneous set of 653 siRNAs collected from the literature. We used this training set to select siRNA features and optimize computational models. We identified 18 parameters that correlate significantly with silencing efficiency. Some of these parameters characterize only the siRNA sequence, while others involve the whole mRNA. Most importantly, we derived an siRNA position-dependent consensus, and optimized the free-energy difference of the 5' and 3' terminal dinucleotides of the siRNA antisense strand. The position-dependent consensus is based on correlation and t-test analyses of the training set, and accounts for both significantly preferred and avoided nucleotides in all sequence positions. On the training set, the two parameters' correlation with silencing efficiency was 0.5 and 0.36, respectively. Among other features, a dinucleotide content index and the frequency of potential targets for siRNA in the mRNA added predictive power to our model (R = 0.55. We showed that our model is effective for predicting the efficiency of siRNAs at different concentrations. We optimized a neural network model on our training set using three parameters characterizing the siRNA sequence, and predicted efficiencies for the test siRNA dataset recently published by Novartis. On this validation set, the correlation coefficient between predicted and observed efficiency was 0.75. Using the same model, we performed a transcriptome-wide analysis of optimal siRNA targets for 22,600 human mRNAs. Conclusion We demonstrated that the properties of the siRNAs themselves are essential for efficient RNA interference. The 5' ends
Thermodynamic modeling of Cu–Ni–Y system coupled with key experiments
Energy Technology Data Exchange (ETDEWEB)
Mezbahul-Islam, Mohammad [Department of Mechanical Engineering, Concordia University, 1455 de Maisonneuve Blvd West, Montreal, Quebec, Montreal H3G 1M8 (Canada); Medraj, Mamoun, E-mail: mmedraj@encs.concordia.ca [Department of Mechanical Engineering, Concordia University, 1455 de Maisonneuve Blvd West, Montreal, Quebec, Montreal H3G 1M8 (Canada); Department of Mechanical and Materials Engineering, Masdar Institute of Science and Technology, Masdar City, Abu Dhabi (United Arab Emirates)
2015-03-01
A complete thermodynamic description of the Cu–Ni–Y ternary system has been obtained using the CALPHAD (CALculation of PHAse Diagram) approach. Ternary solubility of the third element in the binary compounds in the Cu–Ni–Y system is described using sublattice model within the compound energy formalism (CEF) to take into account the recently reported experimental solubility ranges. The modified quasi-chemical model (MQM) has been used to describe the liquid phase in order to account for the presence of short range ordering properly. To study the melting behavior of the Cu–Ni–Y alloys and to verify the consistency of the thermodynamic model with experimental results, 10 key samples were prepared and the phase transformation temperatures were measured using differential scanning calorimeter (DSC). The microstructural characterization and crystallographic analysis of the alloys were carried out using scanning electron microscopy (SEM) coupled with WDS analysis and X-ray diffraction (XRD). Several vertical sections, liquidus projection and isothermal section at 973 K have been calculated and found to be in good agreement with the current experimental data as well as with the literature. - Highlights: • Thermodynamic modeling of the Cu–Ni–Y system has been performed. • Ternary solubilities of the binary compounds have been reproduced. • Modified quasi-chemical model is used to model the liquid phase. • DSC experiments are performed on selected key alloys. • The calculations are consistent with the experimental results.
Advancing dynamic and thermodynamic modelling of magma oceans
Bower, Dan; Wolf, Aaron; Sanan, Patrick; Tackley, Paul
2017-04-01
The techniques for modelling low melt-fraction dynamics in planetary interiors are well-established by supplementing the Stokes equations with Darcy's Law. But modelling high-melt fraction phenomena, relevant to the earliest phase of magma ocean cooling, necessitates parameterisations to capture the dynamics of turbulent flow that are otherwise unresolvable in numerical models. Furthermore, it requires knowledge about the material properties of both solid and melt mantle phases, the latter of which are poorly described by typical equations of state. To address these challenges, we present (1) a new interior evolution model that, in a single formulation, captures both solid and melt dynamics and hence charts the complete cooling trajectory of a planetary mantle, and (2) a physical and intuitive extension of a "Hard Sphere" liquid equation of state (EOS) to describe silicate melt properties for the pressure-temperature (P-T) range of Earth's mantle. Together, these two advancements provide a comprehensive and versatile modelling framework for probing the far-reaching consequences of magma ocean cooling and crystallisation for Earth and other rocky planets. The interior evolution model accounts for heat transfer by conduction, convection, latent heat, and gravitational separation. It uses the finite volume method to ensure energy conservation at each time-step and accesses advanced time integration algorithms by interfacing with PETSc. This ensures it accurately and efficiently computes the dynamics throughout the magma ocean, including within the ultra-thin thermal boundary layers (important for multi-component systems). Our new high P-T liquid EOS accurately captures the energetics and physical properties of the partially molten system whilst retaining the largest number of familiar EOS parameters. We demonstrate the power of our integrated dynamic and EOS model by exploring two crystallisation scenarios for Earth that are dictated by the coincidence of the liquid
GridTool: A surface modeling and grid generation tool
Samareh-Abolhassani, Jamshid
1995-01-01
GridTool is designed around the concept that the surface grids are generated on a set of bi-linear patches. This type of grid generation is quite easy to implement, and it avoids the problems associated with complex CAD surface representations and associated surface parameterizations. However, the resulting surface grids are close to but not on the original CAD surfaces. This problem can be alleviated by projecting the resulting surface grids onto the original CAD surfaces. GridTool is designed primary for unstructured grid generation systems. Currently, GridTool supports VGRID and FELISA systems, and it can be easily extended to support other unstructured grid generation systems. The data in GridTool is stored parametrically so that once the problem is set up, one can modify the surfaces and the entire set of points, curves and patches will be updated automatically. This is very useful in a multidisciplinary design and optimization process. GridTool is written entirely in ANSI 'C', the interface is based on the FORMS library, and the graphics is based on the GL library. The code has been tested successfully on IRIS workstations running IRIX4.0 and above. The memory is allocated dynamically, therefore, memory size will depend on the complexity of geometry/grid. GridTool data structure is based on a link-list structure which allows the required memory to expand and contract dynamically according to the user's data size and action. Data structure contains several types of objects such as points, curves, patches, sources and surfaces. At any given time, there is always an active object which is drawn in magenta, or in their highlighted colors as defined by the resource file which will be discussed later.
The regular conducting fluid model for relativistic thermodynamics
Carter, Brandon
2012-01-01
The "regular" model presented here can be considered to be the most natural solution to the problem of constructing the simplest possible relativistic analogue of the category of classical Fourier--Euler thermally conducting fluid models as characterised by a pair of equations of state for just two dependent variables (an equilibrium density and a conducting scalar). The historically established but causally unsatisfactory solution to this problem due to Eckart is shown to be based on an ansatz that is interpretable as postulating a most unnatural relation between the (particle and entropy) velocities and their associated momenta, which accounts for the well known bad behaviour of that model which has recently been shown to have very pathological mixed-elliptic-hyperbolic comportments. The newer (and more elegant) solution of Landau and Lifshitz has a more mathematically respectable parabolic-hyperbolic comportment, but is still compatible with a well posed initial value problem only in such a restricted limi...
Finite size effects on the phase diagram of the thermodynamical cluster model
Mallik, S; Chaudhuri, G
2016-01-01
The thermodynamical cluster model is known to present a first-order liquid-gas phase transition in the idealized case of an uncharged, infinitely extended medium. However, in most practical applications of this model, the system is finite and charged. In this paper we study how the phase diagram is modified by finite size and Coulomb effects. We show that the thermodynamic anomalies which are associated to the finite system counterpart of first order phase transitions, are correctly reproduced by this effective model. However, approximations in the calculation of the grandcanonical partition sum prevent obtaining the exact mapping between statistical ensembles which should be associated to finite systems. The ensemble inequivalence associated to the transition persists in the presence of Coulomb, but the phase diagram is deeply modified with respect to the simple liquid-gas phase transition characteristic of the neutral system.
A model for exergy analysis and thermodynamic bounds of Stirling refrigerators
Razani, A.; Dodson, C.; Roberts, T.
2010-04-01
A thermodynamic model based on exergy flow through a Stirling Refrigerator is developed. Important irreversibilities of the refrigerator due to external heat transfer with the reservoirs, heat leak, flow and heat transfer in regenerator are included in the model. Expansion and compression efficiencies are introduced in the model to account for the losses in these processes. The effect of a control phase shift between the mass flow rate and pressure across regenerator on the performance of the refrigerator is presented. Analytical solutions representing important quantities in the design of Stirling refrigerators such as the load curve, cooling power and efficiency in terms of basic system input parameters are developed. Thermodynamic bounds for the performance of Stirling refrigerators are obtained. Results indicating a compromise between cooling power and efficiency that are dependent on the constraint of the system are presented and discussed.
Ignition models and simulation of solid propellant of thermodynamic undersea vehicle
Institute of Scientific and Technical Information of China (English)
ZHANG Jin-jun; QIAN Zhi-bo; YANG Jie; YAN Ping
2007-01-01
The starting characteristics of thermodynamic undersea vehicle systems are determined by the geometry, size and combustion area of solid propellants, which directly effect liquid propellant pipeline design. It is necessary to establish accurate burning models for solid propellants. Based on combustion models using powder tings and two different solid ignition grains, namely star-shaped ignition grains and stuffed ignition grains, a mathematic model of the ignition process of the propulsion system was built.With the help of Matlah, a series of calculations were made to determine the effects of different grains on ignition characteristics. The results show that stuffed ignition grain is best suited to be the ignition grain of a thermodynamic undersea vehicle system.
Gesing, Adam J.; Das, Subodh K.
2017-02-01
With United States Department of Energy Advanced Research Project Agency funding, experimental proof-of-concept was demonstrated for RE-12TM electrorefining process of extraction of desired amount of Mg from recycled scrap secondary Al molten alloys. The key enabling technology for this process was the selection of the suitable electrolyte composition and operating temperature. The selection was made using the FactSage thermodynamic modeling software and the light metal, molten salt, and oxide thermodynamic databases. Modeling allowed prediction of the chemical equilibria, impurity contents in both anode and cathode products, and in the electrolyte. FactSage also provided data on the physical properties of the electrolyte and the molten metal phases including electrical conductivity and density of the molten phases. Further modeling permitted selection of electrode and cell construction materials chemically compatible with the combination of molten metals and the electrolyte.
Gesing, Adam J.; Das, Subodh K.
2016-06-01
With United States Department of Energy Advanced Research Project Agency funding, experimental proof-of-concept was demonstrated for RE-12TM electrorefining process of extraction of desired amount of Mg from recycled scrap secondary Al molten alloys. The key enabling technology for this process was the selection of the suitable electrolyte composition and operating temperature. The selection was made using the FactSage thermodynamic modeling software and the light metal, molten salt, and oxide thermodynamic databases. Modeling allowed prediction of the chemical equilibria, impurity contents in both anode and cathode products, and in the electrolyte. FactSage also provided data on the physical properties of the electrolyte and the molten metal phases including electrical conductivity and density of the molten phases. Further modeling permitted selection of electrode and cell construction materials chemically compatible with the combination of molten metals and the electrolyte.
Energy Technology Data Exchange (ETDEWEB)
Krupka, Kenneth M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Cantrell, Kirk J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); McGrail, B. Peter [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
2010-09-01
Permanent storage of anthropogenic CO2 in deep geologic formations is being considered as a means to reduce the concentration of atmospheric CO2 and thus its contribution to global climate change. To ensure safe and effective geologic sequestration, numerous studies have been completed of the extent to which the CO2 migrates within geologic formations and what physical and geochemical changes occur in these formations when CO2 is injected. Sophisticated, computerized reservoir simulations are used as part of field site and laboratory CO2 sequestration studies. These simulations use coupled multiphase flow-reactive chemical transport models and/or standalone (i.e., no coupled fluid transport) geochemical models to calculate gas solubility, aqueous complexation, reduction/oxidation (redox), and/or mineral solubility reactions related to CO2 injection and sequestration. Thermodynamic data are critical inputs to modeling geochemical processes. The adequacy of thermodynamic data for carbonate compounds has been identified as an important data requirement for the successful application of these geochemical reaction models to CO2 sequestration. A review of thermodynamic data for CO2 gas and carbonate aqueous species and minerals present in published data compilations and databases used in geochemical reaction models was therefore completed. Published studies that describe mineralogical analyses from CO2 sequestration field and natural analogue sites and laboratory studies were also reviewed to identify specific carbonate minerals that are important to CO2 sequestration reactions and therefore require thermodynamic data. The results of the literature review indicated that an extensive thermodynamic database exists for CO2 and CH4 gases, carbonate aqueous species, and carbonate minerals. Values of ΔfG298° and/or log Kr,298° are available for essentially all of these compounds. However, log Kr,T° or heat capacity values at temperatures above 298 K exist for less than
Five-Brane Thermodynamics from the Matrix Model
Furuuchi, K; Semenoff, G W
2003-01-01
A certain sector of the matrix model for M-theory on a plane wave background has recently been shown to produce the transverse five-brane. We consider this theory at finite temperature. We find that, at a critical temperature it has a Gross-Witten phase transition which corresponds to deconfinement of the matrix model gauge theory. We interpret the phase transition as the Hagedorn transition of M-theory and of type II string theory in the five-brane background. We also show that there is no Hagedorn behaviour in the transverse membrane background case.
Thermodynamic Models from Fluctuation Solution Theory Analysis of Molecular Simulations
DEFF Research Database (Denmark)
Christensen, Steen; Peters, Günther H.j.; Hansen, Flemming Yssing
2007-01-01
Fluctuation solution theory (FST) is employed to analyze results of molecular dynamics (MD) simulations of liquid mixtures. The objective is to generate parameters for macroscopic GE-models, here the modified Margules model. We present a strategy for choosing the number of parameters included......, Mol. Simul. 33 (4–5) (2007) 449–457.]. The new one has advantages for systems with data points at dilute conditions. Prediction of bubble point pressures using parameters from the two objective functions are compared with experimental data for the binary mixtures methyl acetate–n-pentane and methyl...
Thermodynamic model for bouncing charged particles inside a capacitor
Rezaeizadeh, Amin; Mameghani, Pooya
2013-08-01
We introduce an equation of state for a conducting particle inside a charged parallel-plate capacitor and show that it is similar to the equation of state for an ideal gas undergoing an adiabatic process. We describe a simple experiment that shows reasonable agreement with the theoretical model.
A thermodynamic model to predict wax formation in petroleum fluids
Energy Technology Data Exchange (ETDEWEB)
Coutinho, J.A.P. [Universidade de Aveiro (Portugal). Dept. de Quimica. Centro de Investigacao em Quimica]. E-mail: jcoutinho@dq.ua.pt; Pauly, J.; Daridon, J.L. [Universite de Pau et des Pays de l' Adour, Pau (France). Lab. des Fluides Complexes
2001-12-01
Some years ago the authors proposed a model for the non-ideality of the solid phase, based on the Predictive Local Composition concept. This was first applied to the Wilson equation and latter extended to NRTL and UNIQUAC models. Predictive UNIQUAC proved to be extraordinarily successful in predicting the behaviour of both model and real hydrocarbon fluids at low temperatures. This work illustrates the ability of Predictive UNIQUAC in the description of the low temperature behaviour of petroleum fluids. It will be shown that using Predictive UNIQUAC in the description of the solid phase non-ideality a complete prediction of the low temperature behaviour of synthetic paraffin solutions, fuels and crude oils is achieved. The composition of both liquid and solid phases, the amount of crystals formed and the cloud points are predicted within the accuracy of the experimental data. The extension of Predictive UNIQUAC to high pressures, by coupling it with an EOS/G{sup E} model based on the SRK EOS used with the LCVM mixing rule, is proposed and predictions of phase envelopes for live oils are compared with experimental data. (author)
Thermodynamics of a Simple Three-Dimensional DNA Hairpin Model
Kremer, Kellan; Boggess, Erin; Mask, Walker; Saucedo, Tony; Hansen, JJ; Appelgate, Ian; Jurgensen, Taylor; Santos, Aaron
2016-01-01
We characterize the equation of state for a simple three-dimensional DNA hairpin model using a Metropolis Monte Carlo algorithm. This algorithm was run at constant temperature and fixed separation between the terminal ends of the strand. From the equation of state, we compute the compressibility, thermal expansion coefficient, and specific heat along with adiabatic path.
A THERMODYNAMIC MODEL TO PREDICT WAX FORMATION IN PETROLEUM FLUIDS
Directory of Open Access Journals (Sweden)
J.A.P. Coutinho
2001-12-01
Full Text Available Some years ago the authors proposed a model for the non-ideality of the solid phase, based on the Predictive Local Composition concept. This was first applied to the Wilson equation and latter extended to NRTL and UNIQUAC models. Predictive UNIQUAC proved to be extraordinarily successful in predicting the behaviour of both model and real hydrocarbon fluids at low temperatures. This work illustrates the ability of Predictive UNIQUAC in the description of the low temperature behaviour of petroleum fluids. It will be shown that using Predictive UNIQUAC in the description of the solid phase non-ideality a complete prediction of the low temperature behaviour of synthetic paraffin solutions, fuels and crude oils is achieved. The composition of both liquid and solid phases, the amount of crystals formed and the cloud points are predicted within the accuracy of the experimental data. The extension of Predictive UNIQUAC to high pressures, by coupling it with an EOS/G E model based on the SRK EOS used with the LCVM mixing rule, is proposed and predictions of phase envelopes for live oils are compared with experimental data.
Model for the Prediction of the Hydriding Thermodynamics of Pd-Rh-Co Ternary Alloys
Energy Technology Data Exchange (ETDEWEB)
Teter, D.F.; Thoma, D.J.
1999-03-01
A dilute solution model (with respect to the substitutional alloying elements) has been developed, which accurately predicts the hydride formation and decomposition thermodynamics and the storage capacities of dilute ternary Pd-Rh-Co alloys. The effect of varying the rhodium and cobalt compositions on the thermodynamics of hydride formation and decomposition and hydrogen capacity of several palladium-rhodium-cobalt ternary alloys has been investigated using pressure-composition (PC) isotherms. Alloying in the dilute regime (<10 at.%) causes the enthalpy for hydride formation to linearly decrease with increasing alloying content. Cobalt has a stronger effect on the reduction in enthalpy than rhodium for equivalent alloying amounts. Also, cobalt reduces the hydrogen storage capacity with increasing alloying content. The plateau thermodynamics are strongly linked to the lattice parameters of the alloys. A near-linear dependence of the enthalpy of hydride formation on the lattice parameter was observed for both the binary Pd-Rh and Pd-Co alloys, as well as for the ternary Pd-Rh-Co alloys. The Pd-5Rh-3Co (at. %) alloy was found to have similar plateau thermodynamics as a Pd-10Rh alloy, however, this ternary alloy had a diminished hydrogen storage capacity relative to Pd-10Rh.
New general pore size distribution model by classical thermodynamics application: Activated carbon
Lordgooei, M.; Rood, M.J.; Rostam-Abadi, M.
2001-01-01
A model is developed using classical thermodynamics to characterize pore size distributions (PSDs) of materials containing micropores and mesopores. The thermal equation of equilibrium adsorption (TEEA) is used to provide thermodynamic properties and relate the relative pore filling pressure of vapors to the characteristic pore energies of the adsorbent/adsorbate system for micropore sizes. Pore characteristic energies are calculated by averaging of interaction energies between adsorbate molecules and adsorbent pore walls as well as considering adsorbate-adsorbate interactions. A modified Kelvin equation is used to characterize mesopore sizes by considering variation of the adsorbate surface tension and by excluding the adsorbed film layer for the pore size. The modified-Kelvin equation provides similar pore filling pressures as predicted by density functional theory. Combination of these models provides a complete PSD of the adsorbent for the micropores and mesopores. The resulting PSD is compared with the PSDs from Jaroniec and Choma and Horvath and Kawazoe models as well as a first-order approximation model using Polanyi theory. The major importance of this model is its basis on classical thermodynamic properties, less simplifying assumptions in its derivation compared to other methods, and ease of use.
Induction generator models in dynamic simulation tools
DEFF Research Database (Denmark)
Knudsen, Hans; Akhmatov, Vladislav
1999-01-01
For AC network with large amount of induction generators (windmills) the paper demonstrates a significant discrepancy in the simulated voltage recovery after fault in weak networks when comparing dynamic and transient stability descriptions and the reasons of discrepancies are explained. It is fo......For AC network with large amount of induction generators (windmills) the paper demonstrates a significant discrepancy in the simulated voltage recovery after fault in weak networks when comparing dynamic and transient stability descriptions and the reasons of discrepancies are explained....... It is found to be possible to include a transient model in dynamic stability tools and, then, obtain correct results also in dynamic tools. The representation of the rotating system influences on the voltage recovery shape which is an important observation in case of windmills, where a heavy mill is connected...
Kolesnichenko, A. V.
2004-03-01
A thermodynamic approach to the construction of a phenomenological macroscopic model of developed turbulence in a compressible fluid is considered with regard for the formation of space-time dissipative structures. A set of random variables were introduced into the model as internal parameters of the turbulent-chaos subsystem. This allowed us to obtain, by methods of nonequilibrium thermodynamics, the kinetic Fokker-Planck equation in the configuration space. This equation serves to determine the temporary evolution of the conditional probability distribution function of structural parameters pertaining to the cascade process of fragmentation of large-scale eddies and temperature inhomogeneities and to analyze Markovian stochastic processes of transition from one nonequilibrium stationary turbulent-motion state to another as a result of successive loss of stability caused by a change in the governing parameters. An alternative method for investigating the mechanisms of such transitions, based on the stochastic Langevin-type equation intimately related to the derived kinetic equation, is also considered. Some postulates and physical and mathematical assumptions used in the thermodynamic model of structurized turbulence are discussed in detail. In particular, we considered, using the deterministic transport equation for conditional means, the cardinal problem of the developed approach-the possibility of the existence of asymptotically stable stationary states of the turbulent-chaos subsystem. Also proposed is the nonequilibrium thermodynamic potential for internal coordinates, which extends the well-known Boltzmann-Planck relationship for equilibrium states to the nonequilibrium stationary states of the representing ensemble. This potential is shown to be the Lyapunov function for such states. The relation is also explored between the internal intermittence in the inertial interval of scales and the fluctuations of the energy of dissipation. This study is aimed at
QCD thermodynamics from 3d adjoint Higgs model
Karsch, Frithjof; Patkós, András; Petreczky, P; Szép, Z; Szep, Zs.
1998-01-01
The screening masses of hot SU(N) gauge theory, defined as poles of the corresponding propagators are studied in 3d adjoint Higgs model, considered as an effective theory of QCD, using coupled gap equations and lattice Monte-Carlo simulations (for N=2). Using so-called lambda gauges non-perturbative evidence for gauge independence of the pole masses within this class of gauges is given. A possible application of the screening masses for the resummation of the free energy is discussed.
Molecular Thermodynamic Modeling of Fluctuation Solution Theory Properties
DEFF Research Database (Denmark)
O’Connell, John P.; Abildskov, Jens
2013-01-01
Fluctuation Solution Theory provides relationships between integrals of the molecular pair total and direct correlation functions and the pressure derivative of solution density, partial molar volumes, and composition derivatives of activity coefficients. For dense fluids, the integrals follow...... for densities and gas solubilities, including ionic liquids and complex mixtures such as coal liquids. The approach is especially useful in systems with strong nonidealities. This chapter describes successful application of such modeling to a wide variety of systems treated over several decades and suggests how...
Study of Thermodynamic Properties of Nonstoichiometric Phase with Compound Energy Model
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
Using compound energy model (CEM), the thermodynamic properties of and were evaluated.The evaluation was based on the optimization of ZrO2-CeO2 and ZrO2-CeO1.5 systems, as well as the miscibility gap inCeO1.5-CeO2 system. Except the cubic fluorite structure phase assessed with compound energy model, all the other solutionphases were assessed with subsitutional solution model. The model parameters were evaluated through fitting the selectedexperimental data by means of thermodynamic optimization. A set of parameters with thermodynamics self-consistency wasobtained and satisfactorily described the complex relation between y in and the partial pressure of oxygen atdifferent temperatures, also the interdependence among miscellaneous factors such as temperature, oxygen partial pressure,seem to be reasonable when put into the explanation of pressureless sintering of CeO2-stabilized ZrO2 powder compacts at acontrolled oxygen partial pressure.
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
By introducing a parameter of difference in ferrite formation temperature between binary Fe-C and multicomponent system, and referring to the thermodynamic model for Fe-C binary system, a simplified thermodynamic model for pro-eutectoid ferrite formation in Fe-ΣXi-C multicomponent structural steels (Xi=Mn, Si, Mo, Cr, Ni or Ti, etc) was suggested. The comparison of the calculated Ae3 temperatures with the measured data of steels 42 shows that the relative standard deviation and root-mean-square (RMS) error between them are only 0.71 % and 8.92 K, respectively. However, the deviations between the same measured data and the values calculated from the superelement model are as high as 1.86 % and 23.83 K, respectively. It can be concluded that the simplified thermodynamic model for pro-eutectoid ferrite formation in multicomponent structural steels is acceptable and the calculated Ae3 temperatures are in good agreement with the experimental data.
Chapman, Jeffryes W.; Lavelle, Thomas M.; May, Ryan D.; Litt, Jonathan S.; Guo, Ten-Huei
2014-01-01
A simulation toolbox has been developed for the creation of both steady-state and dynamic thermodynamic software models. This paper describes the Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS), which combines generic thermodynamic and controls modeling libraries with a numerical iterative solver to create a framework for the development of thermodynamic system simulations, such as gas turbine engines. The objective of this paper is to present an overview of T-MATS, the theory used in the creation of the module sets, and a possible propulsion simulation architecture. A model comparison was conducted by matching steady-state performance results from a T-MATS developed gas turbine simulation to a well-documented steady-state simulation. Transient modeling capabilities are then demonstrated when the steady-state T-MATS model is updated to run dynamically.
Chapman, Jeffryes W.; Lavelle, Thomas M.; May, Ryan D.; Litt, Jonathan S.; Guo, Ten-Huei
2014-01-01
A simulation toolbox has been developed for the creation of both steady-state and dynamic thermodynamic software models. This paper describes the Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS), which combines generic thermodynamic and controls modeling libraries with a numerical iterative solver to create a framework for the development of thermodynamic system simulations, such as gas turbine engines. The objective of this paper is to present an overview of T-MATS, the theory used in the creation of the module sets, and a possible propulsion simulation architecture. A model comparison was conducted by matching steady-state performance results from a T-MATS developed gas turbine simulation to a well-documented steady-state simulation. Transient modeling capabilities are then demonstrated when the steady-state T-MATS model is updated to run dynamically.
Phase diagram determination and thermodynamic modeling of the Cu-Mg-Si system
Directory of Open Access Journals (Sweden)
Zhao J.
2016-01-01
Full Text Available 13 ternary Cu-Mg-Si alloys were prepared by means of the powder metallurgy method. Phase equilibria at 500 and 700 oC of the Cu-Mg-Si system were determined using X-ray diffraction analysis (XRD. The existence of 3 ternary compounds in this system was verified: CuMgSi_Sigma (Cu16Mg6Si7, Tau (Cu3Mg2Si, and Laves ((Cu0.8Si0.22(Mg0.88Cu0.12. A thermodynamic modeling for the Cu-Mg-Si system was then conducted on the basis of the experimental data obtained in this work and those critically reviewed from the literature. The complex phase relationship between Laves phase and other phases has been successfully modeled in this work. Comparisons between the calculated and the measured phase diagrams show that most of the experimental data can be reproduced by the presently obtained thermodynamic parameters.
M3FT-15OR0202212: SUBMIT SUMMARY REPORT ON THERMODYNAMIC EXPERIMENT AND MODELING
Energy Technology Data Exchange (ETDEWEB)
McMurray, Jake W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Brese, Robert G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Silva, Chinthaka M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Besmann, Theodore M. [Univ. of South Carolina, Columbia, SC (United States)
2015-09-01
Modeling the behavior of nuclear fuel with a physics-based approach uses thermodynamics for key inputs such as chemical potentials and thermal properties for phase transformation, microstructure evolution, and continuum transport simulations. Many of the lanthanide (Ln) elements and Y are high-yield fission products. The U-Y-O and U-Ln-O ternaries are therefore key subsystems of multi-component high-burnup fuel. These elements dissolve in the dominant urania fluorite phase affecting many of its properties. This work reports on an effort to assess the thermodynamics of the U-Pr-O and U-Y-O systems using the CALPHAD (CALculation of PHase Diagrams) method. The models developed within this framework are capable of being combined and extended to include additional actinides and fission products allowing calculation of the phase equilibria, thermochemical and material properties of multicomponent fuel with burnup.
Thermodynamic geometry of a kagome Ising model in a magnetic field
Energy Technology Data Exchange (ETDEWEB)
Mirza, B., E-mail: b.mirza@cc.iut.ac.ir [Department of Physics, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Talaei, Z., E-mail: zs_talaie@ph.iut.ac.ir [Department of Physics, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)
2013-02-15
We derived the thermodynamic curvature of the Ising model on a kagome lattice under the presence of an external magnetic field. The curvature was found to have a singularity at the critical point. We focused on the zero field case to derive thermodynamic curvature and its components near the criticality. According to standard scaling, scalar curvature R behaves as |β−β{sub c}|{sup α−2} for α>0 where β is the inverse temperature and α is the critical exponent of specific heat. In the model considered here in which α is zero, we found that R behaves as |β−β{sub c}|{sup α−1}.
Es-haghi, Siamak Shams
2012-01-01
In this paper, diffusion in polymer solutions undergoing evaporation of solvent is modeled as a coupled heat and mass transfer problem with moving boundary condition within the framework of nonequilibrium thermodynamics. The proposed governing equations derived from the fundamental equation of classical thermodynamics using the local equilibrium hypothesis display more complex connection between heat and non-convective mass fluxes than what has been presented in the previous research works. Numerical computations, performed using an explicit finite difference scheme, indicate that the model is able to capture the effect of thermal diffusion in polymer solutions. This effect manifests itself as an increase in local concentration of solvent near warm substrates during solution casting process.
A new model for thermodynamic analysis on wetting behavior of superhydrophobic surfaces
Energy Technology Data Exchange (ETDEWEB)
Zhang Hongyun [Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education and Faculty of Materials, Optoelectronics and Physics, Xiangtan University, Xiangtan 411105 (China); Li Wen, E-mail: liwen@xtu.edu.cn [Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education and Faculty of Materials, Optoelectronics and Physics, Xiangtan University, Xiangtan 411105 (China); Fang Guoping [Department of mechanical Engineering, University of Alberta, Edmonton, AB, T6G 2G8 (Canada)
2012-01-15
Superhydrophobic surfaces have shown inspiring applications in microfluidics, and self-cleaning coatings owing to water-repellent and low-friction properties. However, thermodynamic mechanism responsible for contact angle hysteresis (CAH) and free energy barrier (FEB) have not been understood completely yet. In this work, we propose an intuitional 3-dimension (3D) droplet model along with a reasonable thermodynamic approach to gain a thorough insight into the physical nature of CAH. Based on this model, the relationships between radius of three-phase contact line, change in surface free energy (CFE), average or local FEB and contact angle (CA) are established. Moreover, a thorough theoretical consideration is given to explain the experimental phenomena related to the superhydrophobic behavior. The present study can therefore provide some guidances for the practical fabrications of the superhydrophobic surfaces.
Fagerström, Anton; Kocherbitov, Vitaly; Ruzgas, Tautgirdas; Westbye, Peter; Bergström, Karin; Engblom, Johan
2013-03-01
The main objective of this study was to investigate the mechanism of molecular transport across the cuticle of Clivia leaves. In vitro diffusion methodology was used to investigate the transport of a systemic fungicide, tebuconazole, over a model silicone membrane, enzymatically isolated cuticle membranes, and dermatomed leaves. It was shown that dermatomed leaves may replace enzymatically isolated cuticles. Furthermore, the effects of two surfactants, C(10)EO(7) and C(8)G(1.6), on the fungicide transport were investigated. Tebuconazole cuticle permeation was described using Fick's first law of diffusion, expressed by the thermodynamic activity of the solute in the membrane. A new method for calculation of diffusion coefficients in the membrane is proposed. To access the thermodynamic activity of the fungicide in the membranes, sorption isotherms of tebuconazole in the membrane materials studied were recorded. The thermodynamic activity of the fungicide in aqueous solutions was calculated from solubility data. For that purpose, the effect of surfactants on tebuconazole solubility was studied. The results show that addition of surfactants allows for higher concentrations of tebuconazole available for penetration. Nonetheless, at a fixed fungicide thermodynamic activity, all formulations produced the same flux over the silicone membrane independently on the fungicide concentration. This shows that the driving force across non-responding membranes is the gradient of thermodynamic activity, rather than the gradient of the fungicide concentration. In case of leaves, surfactants induced the same quantitative increase in both flux and diffusion coefficient of solute in the cuticle, while the cuticle-water partition coefficient was unaffected.
A Thermodynamic Approach to Predict Formation Enthalpies of Ternary Systems Based on Miedema's Model
Mousavi, Mahbubeh Sadat; Abbasi, Roozbeh; Kashani-Bozorg, Seyed Farshid
2016-07-01
A novel modification to the thermodynamic semi-empirical Miedema's model has been made in order to provide more precise estimations of formation enthalpy in ternary alloys. The original Miedema's model was modified for ternary systems based on surface concentration function revisions. The results predicted by the present model were found to be in excellent agreement with the available experimental data of over 150 ternary intermetallic compounds. The novel proposed model is capable of predicting formation enthalpies of ternary intermetallics with small discrepancies of ≤20 kJ/mol as well as providing reliable enthalpy variations.
An MCMC Circumstellar Disks Modeling Tool
Wolff, Schuyler; Perrin, Marshall D.; Mazoyer, Johan; Choquet, Elodie; Soummer, Remi; Ren, Bin; Pueyo, Laurent; Debes, John H.; Duchene, Gaspard; Pinte, Christophe; Menard, Francois
2016-01-01
We present an enhanced software framework for the Monte Carlo Markov Chain modeling of circumstellar disk observations, including spectral energy distributions and multi wavelength images from a variety of instruments (e.g. GPI, NICI, HST, WFIRST). The goal is to self-consistently and simultaneously fit a wide variety of observables in order to place constraints on the physical properties of a given disk, while also rigorously assessing the uncertainties in the derived properties. This modular code is designed to work with a collection of existing modeling tools, ranging from simple scripts to define the geometry for optically thin debris disks, to full radiative transfer modeling of complex grain structures in protoplanetary disks (using the MCFOST radiative transfer modeling code). The MCMC chain relies on direct chi squared comparison of model images/spectra to observations. We will include a discussion of how best to weight different observations in the modeling of a single disk and how to incorporate forward modeling from PCA PSF subtraction techniques. The code is open source, python, and available from github. Results for several disks at various evolutionary stages will be discussed.
2011-01-01
Modeling the Thermodynamic and Transport Properties of Decahydronaphthalene/Propane Mixtures: Phase Equilibria , Density, and Viscosity Nathaniel...Decahydronaphthalene/Propane Mixtures: Phase Equilibria , Density, And Viscosity 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d...Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 Keywords: phase equilibria ; modified Sanchez-Lacombe equation of state
Energy Technology Data Exchange (ETDEWEB)
Minelli, Matteo; Doghieri, Ferruccio [Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali (DICAM), Centro Interdipartimentale per la Ricerca Industriale - Meccanica Avanzata e Materiali (CIRI-MAM), Alma Mater Studiorum - Università di Bologna, via Terracini 28 - (Italy)
2014-05-15
Data for kinetics of mass uptake from vapor sorption experiments in thin glassy polymer samples are here interpreted in terms of relaxation times for volume dilation. To this result, both models from non-equilibrium thermodynamics and from mechanics of volume relaxation contribute. Different kind of sorption experiments have been considered in order to facilitate the direct comparison between kinetics of solute induced volume dilation and corresponding data from process driven by pressure or temperature jumps.
Thermodynamic modeling of the RE–Pb (RE = Sc, Dy, Gd) systems
Energy Technology Data Exchange (ETDEWEB)
Iddaoudi, A., E-mail: iddaoudi19@gmail.com [Laboratoire de Thermodynamique et Energétique, LTE, Université Ibn-Zohr, B.P. 8106 Agadir (Morocco); Servant, C., E-mail: colette.servant@orange.fr [Laboratoire de Physicochimie de l’Etat Solide, ICMMO, Université Paris-Sud, 91405 Orsay Cedex (France); Selhaoui, N.; Kardellass, S.; Mahdouk, K.; Bouirden, L. [Laboratoire de Thermodynamique et Energétique, LTE, Université Ibn-Zohr, B.P. 8106 Agadir (Morocco)
2014-03-15
Highlights: • Rare earth (RE) and Pb alloys or compounds are interesting as magnetic materials. • The phase diagrams and thermodynamic properties of RE–Pb (RE = Sc, Dy, Gd) systems have been assessed. • The CALPHAD method was used with the Redlich–Kister model to optimize the solution phases. • A self-consistent set of thermodynamic parameters has been evaluated. • A good agreement was found between the calculation and experiments. -- Abstract: The phase diagrams and thermodynamic properties of RE–Pb (RE = Sc, Dy, Gd) systems have been assessed by means of the CALPHAD method. The solution phases (liquid, fcc, bcc and hcp) were described by the sublattice formalism and the excess term of the Gibbs energy with the Redlich–Kister equation. The stoichiometric intermetallic compounds (Sc{sub 5}Pb{sub 3}, Sc{sub 6}Pb{sub 5}, Dy{sub 5}Pb{sub 4}, DyPb, DyPb{sub 2}, DyPb{sub 3}, β-Gd{sub 5}Pb{sub 4}, α-Gd{sub 5}Pb{sub 4}, Gd{sub 11}Pb{sub 10}, Gd{sub 6}Pb{sub 7}, GdPb{sub 2} and GdPb{sub 2}) were modeled as line compounds. The non-stoichiometric Dy{sub 5}Pb{sub 3} and Gd{sub 5}Pb{sub 3} phases with a narrow homogeneity range were modeled using a two-sublattice model with substitution. A consistent set of the thermodynamic parameters leading to a reasonable agreement between the calculated results and literature data was obtained.
Thermodynamic Modeling of an Ammonia-Water Absorption System Associated with a Microturbine
Edson Bazzo; Janilson Arcangelo Rossa
2009-01-01
Thermodynamic modeling and Second Law analysis of a small-scale cogeneration system consisting of a 5 refrigerant ton absorption chiller connected by a thermosyphon heat exchanger to a 28 kWe natural gas microturbine are presented. The proposed configuration changes the heat source of the absorption chiller, replacing the original natural gas burning system. A computational algorithm was programmed to analyze the global efficiency of the combined cooling and power plant and the coefficient of...
WMT: The CSDMS Web Modeling Tool
Piper, M.; Hutton, E. W. H.; Overeem, I.; Syvitski, J. P.
2015-12-01
The Community Surface Dynamics Modeling System (CSDMS) has a mission to enable model use and development for research in earth surface processes. CSDMS strives to expand the use of quantitative modeling techniques, promotes best practices in coding, and advocates for the use of open-source software. To streamline and standardize access to models, CSDMS has developed the Web Modeling Tool (WMT), a RESTful web application with a client-side graphical interface and a server-side database and API that allows users to build coupled surface dynamics models in a web browser on a personal computer or a mobile device, and run them in a high-performance computing (HPC) environment. With WMT, users can: Design a model from a set of components Edit component parameters Save models to a web-accessible server Share saved models with the community Submit runs to an HPC system Download simulation results The WMT client is an Ajax application written in Java with GWT, which allows developers to employ object-oriented design principles and development tools such as Ant, Eclipse and JUnit. For deployment on the web, the GWT compiler translates Java code to optimized and obfuscated JavaScript. The WMT client is supported on Firefox, Chrome, Safari, and Internet Explorer. The WMT server, written in Python and SQLite, is a layered system, with each layer exposing a web service API: wmt-db: database of component, model, and simulation metadata and output wmt-api: configure and connect components wmt-exe: launch simulations on remote execution servers The database server provides, as JSON-encoded messages, the metadata for users to couple model components, including descriptions of component exchange items, uses and provides ports, and input parameters. Execution servers are network-accessible computational resources, ranging from HPC systems to desktop computers, containing the CSDMS software stack for running a simulation. Once a simulation completes, its output, in NetCDF, is packaged
Lava-substrate heat transfer: Laboratory experiments and thermodynamic modeling
Rumpf, M.; Fagents, S. A.; Hamilton, C. W.; Wright, R.; Crawford, I.
2012-12-01
We have performed laboratory experiments and numerical modeling to investigate the heat transfer from a lava flow into various substrate materials, focusing on the effects of the differing thermophysical properties of substrate materials. Initial motivation for this project developed from the desire to understand the loss of solar wind volatiles embedded in lunar regolith deposits that were subsequently covered by a lava flow. The Moon lacks a significant atmosphere and magnetosphere, leaving the surface regolith exposed to bombardment by solar flare and solar wind particles, and by the cosmogenic products of galactic cosmic rays. Preservation of particle-rich regolith deposits may have occurred by the emplacement of an active lava flow on top of the regolith layer, provided the embedded particles survive heating by the lava. During future expeditions to the lunar surface, ancient regolith deposits could be sampled through surface drilling to extract the extra-lunar particles, revealing a history of the solar activity and galactic events not available on the Earth. This project also has important implications for terrestrial lava flows, particularly in the prediction of lava flow hazards. Lava erupted on Earth may be emplaced on various substrates, including solid lava rock, volcanic tephra, sands, soils, etc. The composition, grain size, consolidation, moisture content, etc. of these materials will vary greatly and have different effects on the cooling of the flow. Accounting for specific properties of the substrate could be an important improvement in lava flow models We have performed laboratory experiments in collaboration with the Department of Art and Art History at the University of Hawaii at Manoa in which ~5-6 kg of basalt, collected at Kilauea Volcano, Hawaii, is melted to ~1200 °C. The lava is poured into a device constructed of calcium silicate sheeting that has been filled with a solid or particulate substrate material and embedded with thermocouples
Comparison of BrainTool to other UML modeling and model transformation tools
Nikiforova, Oksana; Gusarovs, Konstantins
2017-07-01
In the last 30 years there were numerous model generated software systems offered targeting problems with the development productivity and the resulting software quality. CASE tools developed due today's date are being advertised as having "complete code-generation capabilities". Nowadays the Object Management Group (OMG) is calling similar arguments in regards to the Unified Modeling Language (UML) models at different levels of abstraction. It is being said that software development automation using CASE tools enables significant level of automation. Actual today's CASE tools are usually offering a combination of several features starting with a model editor and a model repository for a traditional ones and ending with code generator (that could be using a scripting or domain-specific (DSL) language), transformation tool to produce the new artifacts from the manually created and transformation definition editor to define new transformations for the most advanced ones. Present paper contains the results of CASE tool (mainly UML editors) comparison against the level of the automation they are offering.
Bohr's semiclassical model of the black hole thermodynamics
Directory of Open Access Journals (Sweden)
Panković V.
2008-01-01
Full Text Available We propose a simple procedure for evaluating the main attributes of a Schwarzschild's black hole: Bekenstein-Hawking entropy, Hawking temperature and Bekenstein's quantization of the surface area. We make use of the condition that the circumference of a great circle on the black hole horizon contains finite and whole number of the corresponding reduced Compton's wavelength. It is essentially analogous to Bohr's quantization postulate in Bohr's atomic model interpreted by de Broglie's relation. It implies the standard meaning of the black hole entropy corresponding to surface of the quantum variation of the great circles on the black hole horizon surface area. We present black hole radiation in the form conceptually analogous to Bohr's postulate on the photon emission by discrete quantum jump of the electron within the Old quantum theory. This enables us, in accordance with Heisenberg's uncertainty relation and Bohr's correspondence principle, to make a rough estimate of the time interval for black hole evaporation, which turns out very close to time interval predicted by the standard Hawking's theory. Our calculations confirm Bekenstein's semiclassical result for the energy quantization, in variance with Frasca's (2005 calculations. Finally we speculate about the possible source-energy distribution within the black hole horizon.
Directory of Open Access Journals (Sweden)
Xuan L Liu
Full Text Available The phase relations and thermodynamic properties of the condensed Al-Co-Cr ternary alloy system are investigated using first-principles calculations based on density functional theory (DFT and phase-equilibria experiments that led to X-ray diffraction (XRD and electron probe micro-analysis (EPMA measurements. A thermodynamic description is developed by means of the calculations of phase diagrams (CALPHAD method using experimental and computational data from the present work and the literature. Emphasis is placed on modeling the bcc-A2, B2, fcc-γ, and tetragonal-σ phases in the temperature range of 1173 to 1623 K. Liquid, bcc-A2 and fcc-γ phases are modeled using substitutional solution descriptions. First-principles special quasirandom structures (SQS calculations predict a large bcc-A2 (disordered/B2 (ordered miscibility gap, in agreement with experiments. A partitioning model is then used for the A2/B2 phase to effectively describe the order-disorder transitions. The critically assessed thermodynamic description describes all phase equilibria data well. A2/B2 transitions are also shown to agree well with previous experimental findings.
Thermodynamic data base needs for modeling studies of the Yucca Mountain project
Energy Technology Data Exchange (ETDEWEB)
Palmer, C.E.A.; Silva, R.J. [Lawrence Livermore National Lab., CA (United States). Nuclear Chemistry Div.; Bucher, J.J. [Lawrence Berkeley Lab., CA (United States). Materials and Chemical Sciences Div.
1996-07-12
This document is the first in a series of documents outlining the thermodynamic data needs for performing geochemical modeling calculations in support of various waste package performance assessment activities for the Yucca Mountain Project. The documents are intended to identify and justify the critical thermodynamic data needs for the data base to be used with the models. The Thermodynamic Data Determinations task supplies data needed to resolve performance or design issues and the development of the data base will remain an iterative process as needs change or data improve. For example, data are needed to predict: (1) major ion groundwater chemistry and its evolution, (2) mineral stabilities and evolution, (3) engineered barrier near-field transport and retardation properties, (4) changes in geochemical conditions and processes, (5) solubilities, speciation and transport of waste radionuclides and (6) the dissolution of corrosion of construction and canister materials and the effect on groundwater chemistry and radionuclide solubilities and transport. The system is complex and interactive, and data need to be supplied in order to model the changes and their effect on other components of the system, e.g., temperature, pH and redox conditions (Eh). Through sensitivity and uncertainty analyses, the critical data and system parameters will be identified and the acceptable variations in them documented.
Istok, J. D.
2007-12-01
We present an approach that couples thermodynamic descriptions for microbial growth and geochemical reactions to provide quantitative predictions for the effects of substrate addition or other enviornmental perturbations on microbial community composition. A synthetic microbial community is defined as a collection of defined microbial groups; each with a growth equation derived from bioenergetic principles. The growth equations and standard-state free energy yields are appended to a thermodynamic database for geochemical reactions and the combined equations are solved simultaneously to predict coupled changes in microbial biomass, community composition, and system geochemistry. This approach, with a single set of thermodynamic parameters (one for each growth equation), was used to predict the results of laboratory and field experiments at three geochemically diverse research sites. Predicted effects of ethanol or acetate addition on radionuclide and heavy metal solubility, major ion geochemistry, mineralogy, microbial biomass and community composition were in general agreement with experimental observations although the available experimental data precluded rigorous model testing. Model simulations provide insight into the long-standing difficulty in transferring experimental results from the laboratory to the field and from one site to the next, especially if the form, concentration, or delivery of growth substrate is varied from one experiment to the next. Although originally developed for use in better understanding bioimmobilization of radionuclides and heavy metals via reductive precipitation, the modeling approach is potentially useful for exploring the coupling of microbial growth and geochemical reactions in a variety of basic and applied biotechnology research settings.
Directory of Open Access Journals (Sweden)
Wei Wang
2013-01-01
Full Text Available The precipitation of wax/solid paraffin during production, transportation, and processing of crude oil is a serious problem. It is essential to have a reliable model to predict the wax appearance temperature and the amount of solid precipitated at different conditions. This paper presents a work to predict the solid precipitation based on solid-liquid equilibrium with regular solution-molecular thermodynamic theory and characterization of the crude oil plus fraction. Due to the differences of solubility characteristics between solid and liquid phase, the solubility parameters of liquid and solid phase are calculated by a modified model. The heat capacity change between solid and liquid phase is considered and estimated in the thermodynamic model. An activity coefficient based thermodynamic method combined with two characteristic methods to calculate wax precipitation in crude oil, especially heavy oil, has been tested with experimental data. The results show that the wax appearance temperature and the amount of weight precipitated can be predicted well with the experimental data.
Decreasing Kd uncertainties through the application of thermodynamic sorption models.
Domènech, Cristina; García, David; Pękala, Marek
2015-09-15
Radionuclide retardation processes during transport are expected to play an important role in the safety assessment of subsurface disposal facilities for radioactive waste. The linear distribution coefficient (Kd) is often used to represent radionuclide retention, because analytical solutions to the classic advection-diffusion-retardation equation under simple boundary conditions are readily obtainable, and because numerical implementation of this approach is relatively straightforward. For these reasons, the Kd approach lends itself to probabilistic calculations required by Performance Assessment (PA) calculations. However, it is widely recognised that Kd values derived from laboratory experiments generally have a narrow field of validity, and that the uncertainty of the Kd outside this field increases significantly. Mechanistic multicomponent geochemical simulators can be used to calculate Kd values under a wide range of conditions. This approach is powerful and flexible, but requires expert knowledge on the part of the user. The work presented in this paper aims to develop a simplified approach of estimating Kd values whose level of accuracy would be comparable with those obtained by fully-fledged geochemical simulators. The proposed approach consists of deriving simplified algebraic expressions by combining relevant mass action equations. This approach was applied to three distinct geochemical systems involving surface complexation and ion-exchange processes. Within bounds imposed by model simplifications, the presented approach allows radionuclide Kd values to be estimated as a function of key system-controlling parameters, such as the pH and mineralogy. This approach could be used by PA professionals to assess the impact of key geochemical parameters on the variability of radionuclide Kd values. Moreover, the presented approach could be relatively easily implemented in existing codes to represent the influence of temporal and spatial changes in geochemistry
Greco, Cristina; Yiang, Ying; Kremer, Kurt; Chen, Jeff; Daoulas, Kostas
Polymer liquid crystals, apart from traditional applications as high strength materials, are important for new technologies, e.g. Organic Electronics. Their studies often invoke mesoscale models, parameterized to reproduce thermodynamic properties of the real material. Such top-down strategies require advanced simulation techniques, predicting accurately the thermodynamics of mesoscale models as a function of characteristic features and parameters. Here a recently developed model describing nematic polymers as worm-like chains interacting with soft directional potentials is considered. We present a special thermodynamic integration scheme delivering free energies in particle-based Monte Carlo simulations of this model, avoiding thermodynamic singularities. Conformational and structural properties, as well as Helmholtz free energies are reported as a function of interaction strength. They are compared with state-of-art SCF calculations invoking a continuum analog of the same model, demonstrating the role of liquid-packing and fluctuations.
Energy Technology Data Exchange (ETDEWEB)
Yang, Ying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Field, Kevin G [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Allen, Todd R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Busby, Jeremy T [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2015-09-01
Irradiation-assisted stress corrosion cracking (IASCC) of austenitic stainless steels in Light Water Reactor (LWR) components has been linked to changes in grain boundary composition due to irradiation induced segregation (RIS). This work developed a robust RIS modeling tool to account for thermodynamics and kinetics of the atom and defect transportation under combined thermal and radiation conditions. The diffusion flux equations were based on the Perks model formulated through the linear theory of the thermodynamics of irreversible processes. Both cross and non-cross phenomenological diffusion coefficients in the flux equations were considered and correlated to tracer diffusion coefficients through Manning’s relation. The preferential atomvacancy coupling was described by the mobility model, whereas the preferential atom-interstitial coupling was described by the interstitial binding model. The composition dependence of the thermodynamic factor was modeled using the CALPHAD approach. Detailed analysis on the diffusion fluxes near and at grain boundaries of irradiated austenitic stainless steels suggested the dominant diffusion mechanism for chromium and iron is via vacancy, while that for nickel can swing from the vacancy to the interstitial dominant mechanism. The diffusion flux in the vicinity of a grain boundary was found to be greatly influenced by the composition gradient formed from the transient state, leading to the oscillatory behavior of alloy compositions in this region. This work confirms that both vacancy and interstitial diffusion, and segregation itself, have important roles in determining the microchemistry of Fe, Cr, and Ni at irradiated grain boundaries in austenitic stainless steels.
Development of a thermodynamic model for a cold cycle 3He-4He dilution refrigerator
Mueller, B. W.; Miller, F. K.
2016-10-01
A thermodynamic model of a 3He-4He cold cycle dilution refrigerator with no actively-driven mechanical components is developed and investigated. The refrigerator employs a reversible superfluid magnetic pump, passive check valves, a phase separation chamber, and a series of recuperative heat exchangers to continuously circulate 3He-4He and maintain a 3He concentration gradient across the mixing chamber. The model predicts cooling power and mixing chamber temperature for a range of design and operating parameters, allowing an evaluation of feasibility for potential 3He-4He cold cycle dilution refrigerator prototype designs. Model simulations for a prototype refrigerator design are presented.
Energy Technology Data Exchange (ETDEWEB)
V. Glazoff, Michael; Charit, Indrajt; Sabharwall, Piyush
2014-09-17
An evaluation of thermodynamic aspects of hot corrosion of the superalloys Haynes 242 and HastelloyTM N in the eutectic mixtures of KF and ZrF4 is carried out for development of Advanced High Temperature Reactor (AHTR). This work models the behavior of several superalloys, potential candidates for the AHTR, using computational thermodynamics tool (ThermoCalc), leading to the development of thermodynamic description of the molten salt eutectic mixtures, and on that basis, mechanistic prediction of hot corrosion. The results from these studies indicated that the principal mechanism of hot corrosion was associated with chromium leaching for all of the superalloys described above. However, HastelloyTM N displayed the best hot corrosion performance. This was not surprising given it was developed originally to withstand the harsh conditions of molten salt environment. However, the results obtained in this study provided confidence in the employed methods of computational thermodynamics and could be further used for future alloy design efforts. Finally, several potential solutions to mitigate hot corrosion were proposed for further exploration, including coating development and controlled scaling of intermediate compounds in the KF-ZrF4 system.
Some uses and misuses of thermodynamic models for dilute liquid solutions
Energy Technology Data Exchange (ETDEWEB)
Cabezas, H. Jr. (Univ. of Arizona, Tucson, AZ (United States). Dept. of Chemical Engineering); O' Connell, J.P. (Univ. of Virginia, Charlottesville, VA (United States). Dept. of Chemical Engineering)
1993-11-01
Polymer solubility, liquid-liquid solute partitioning, and electrolyte activities are examples of important thermodynamic properties of liquid systems where components are found at low concentrations in solvents. It is common to analyze solution composition data with expressions such as osmotic virial expansions and/or Debye-Hueckel electrostatic models without careful regard for the correct relationship of the coefficients to the molecular solute-solute interactions. The purpose of this work is to (1) note the different thermodynamic variables of solutions, (2) briefly summarize the connections of the coefficients to molecular interactions, (3) demonstrate how the differences are related to experimental values, and (4) illustrate practical cases in phase equilibria of polymeric and ionic solutes.
Institute of Scientific and Technical Information of China (English)
COQUELET Christophe; RICHON Dominique
2007-01-01
In 1987, the Montreal Protocol prohibited the worldwide use and production of chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) and hydro fluorocarbons (HFCs) were proposed as alternative refrigerants. Unfortunately,HFCs have non negligible global warning potential and therefore new refrigerants must be proposed or old refrigerants must be used associated with HFC. Accurate experimental thermodynamic data and predictive techniques are required for better understanding of the performance of the newly proposed refrigerants. In this communication, experimental techniques based on either analytic or synthetic methods are first described. Data are reported. Then two newly developed predictive models based on thermodynamic approach with the isofugacity criterion and artificial neural network method are presented. The results can provide better evaluation of refrigerants, especially with the aim of studying global warning effects.
Modeling thermodynamics of Fe-N phases; characterisation of e-Fe2N1-z
DEFF Research Database (Denmark)
Pekelharing, M.I.; Böttger, A.; Somers, Marcel A.J.
1999-01-01
In order to arrive at modeling the thermodynamics of Fe-N phases, including long-range (LRO) and short-range ordering (SRO) of the N atoms, it is important to understand the role of N interstitially dissolved in an Fe-host lattice. The crystal structure of -Fe2N1-z consists of an h.c.p. iron...... sublattice and a hexagonal nitrogen sublattice formed by octahedral interstices of the Fe sublattice [1]. Two ground-state structures have been proposed for the ordered arrangement of the N atoms on their own sublattice [1], which were shown to be thermodynamically favourable [2]: configuration A for Fe2N1...... investigated with X-ray diffraction (XRD) and Mössbauer spectroscopy. A thermodynamic model accounting for the two configurations of LRO of the N atoms [2,3] was fitted to the N-absorption isotherm at 723 K and resulted in the occupancies of the sites of the nitrogen sublattice. A miscibility gap between...
Weigand, T. M.; Miller, C. T.; Dye, A. L.; Gray, W. G.; McClure, J. E.; Rybak, I.
2015-12-01
The thermodynamically constrained averaging theory (TCAT) has been usedto formulate general classes of porous medium models, including newmodels for two-fluid-phase flow. The TCAT approach provides advantagesthat include a firm connection between the microscale, or pore scale,and the macroscale; a thermodynamically consistent basis; explicitinclusion of factors such as interfacial areas, contact angles,interfacial tension, and curvatures; and dynamics of interface movementand relaxation to an equilibrium state. In order to render the TCATmodel solvable, certain closure relations are needed to relate fluidpressure, interfacial areas, curvatures, and relaxation rates. In thiswork, we formulate and solve a TCAT-based two-fluid-phase flow model. We detail the formulation of the model, which is a specific instancefrom a hierarchy of two-fluid-phase flow models that emerge from thetheory. We show the closure problem that must be solved. Using recentresults from high-resolution microscale simulations, we advance a set ofclosure relations that produce a closed model. Lastly, we solve the model using a locally conservative numerical scheme and compare the TCAT model to the traditional model.
Institute of Scientific and Technical Information of China (English)
ZHOU Xiaopeng; SU Xueli; SUN Yan
2007-01-01
A study of nonlinear competitive adsorption equilibria of proteins is of fundamental importance in understanding the behavior of preparative chromatographic separation.This work describes the nonlinear binary protein adsorption equilibria on ion exchangers by the statistical thermodynamic (ST) model.The single-component and binary protein adsorption isotherms of bovine hemoglobin (Hb) and bovine serum albumin(BSA)on SP Sepharose FF were determined by batch adsorption experiments in 0.05 mol/L sodium acetate buffer at three pH values(4.5,5.0 and 5.5)and three NaCl concentrations(0.05,0.10 and 0.15 mol/L)at pH 5.0.The ST model was found to depict the effects of pH and ionic strength on the single-component equilibria well,with model parameters depending on the pH and ionic strength.Moreover,the ST model gave acceptable fitting to the binary adsorption data with the fltted singlecomponent model parameters,leading to the estimation of the binary ST model parameter.The effects of pH and ionic strength on the model parameters are reasonably interpreted by the electrostatic and thermodynamic theories.Results demonstrate the availability of the ST model for describing nonlinear competitive protein adsorption equilibria in the presence of two proteins.
Towards a Realistic, Data-Driven Thermodynamic MHD Model of the Global Solar Corona
Downs, Cooper; van der Holst, Bart; Lugaz, Noé; Sokolov, Igor V; Gombosi, Tamas I
2009-01-01
In this work we describe our implementation of a thermodynamic energy equation into the global corona model of the Space Weather Modeling Framework (SWMF), and its development into the new Lower Corona (LC) model. This work includes the integration of the additional energy transport terms of coronal heating, electron heat conduction, and optically thin radiative cooling into the governing magnetohydrodynamic (MHD) energy equation. We examine two different boundary conditions using this model; one set in the upper transition region (the Radiative Energy Balance model), as well as a uniform chromospheric condition where the transition region can be modeled in its entirety. Via observation synthesis from model results and the subsequent comparison to full sun extreme ultraviolet (EUV) and soft X-Ray observations of Carrington Rotation (CR) 1913 centered on Aug 27, 1996, we demonstrate the need for these additional considerations when using global MHD models to describe the unique conditions in the low corona. Th...
Collaboro: a collaborative (meta modeling tool
Directory of Open Access Journals (Sweden)
Javier Luis Cánovas Izquierdo
2016-10-01
Full Text Available Software development is becoming more and more collaborative, emphasizing the role of end-users in the development process to make sure the final product will satisfy customer needs. This is especially relevant when developing Domain-Specific Modeling Languages (DSMLs, which are modeling languages specifically designed to carry out the tasks of a particular domain. While end-users are actually the experts of the domain for which a DSML is developed, their participation in the DSML specification process is still rather limited nowadays. In this paper, we propose a more community-aware language development process by enabling the active participation of all community members (both developers and end-users from the very beginning. Our proposal, called Collaboro, is based on a DSML itself enabling the representation of change proposals during the language design and the discussion (and trace back of possible solutions, comments and decisions arisen during the collaboration. Collaboro also incorporates a metric-based recommender system to help community members to define high-quality notations for the DSMLs. We also show how Collaboro can be used at the model-level to facilitate the collaborative specification of software models. Tool support is available both as an Eclipse plug-in a web-based solution.
A thermodynamic model of mixed organic-inorganic aerosols to predict activity coefficients
Zuend, A.; Marcolli, C.; Luo, B. P.; Peter, T.
2008-08-01
Tropospheric aerosols contain mixtures of inorganic salts, acids, water, and a large variety of organic compounds. Interactions between these substances in liquid mixtures lead to discrepancies from ideal thermodynamic behaviour. By means of activity coefficients, non-ideal behaviour can be taken into account. We present here a thermodynamic model named AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) that is able to calculate activity coefficients covering inorganic, organic, and organic-inorganic interactions in aqueous solutions over a wide concentration range. This model is based on the activity coefficient model LIFAC by Yan et al. (1999) that we modified and reparametrised to better describe atmospherically relevant conditions and mixture compositions. Focusing on atmospheric applications we considered H+, Li+, Na+, K+, NH+4, Mg2+, Ca2+, Cl-, Br-, NO-3, HSO-4, and SO2-4 as cations and anions and a wide range of alcohols/polyols composed of the functional groups CHn and OH as organic compounds. With AIOMFAC, the activities of the components within an aqueous electrolyte solution are well represented up to high ionic strength. Most notably, a semi-empirical middle-range parametrisation of direct organic-inorganic interactions in alcohol+water+salt solutions strongly improves the agreement between experimental and modelled activity coefficients. At room temperature, this novel thermodynamic model offers the possibility to compute equilibrium relative humidities, gas/particle partitioning and liquid-liquid phase separations with high accuracy. In further studies, other organic functional groups will be introduced. The model framework is not restricted to specific ions or organic compounds and is therefore also applicable for other research topics.
A thermodynamic model of mixed organic-inorganic aerosols to predict activity coefficients
Directory of Open Access Journals (Sweden)
A. Zuend
2008-08-01
Full Text Available Tropospheric aerosols contain mixtures of inorganic salts, acids, water, and a large variety of organic compounds. Interactions between these substances in liquid mixtures lead to discrepancies from ideal thermodynamic behaviour. By means of activity coefficients, non-ideal behaviour can be taken into account. We present here a thermodynamic model named AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients that is able to calculate activity coefficients covering inorganic, organic, and organic-inorganic interactions in aqueous solutions over a wide concentration range. This model is based on the activity coefficient model LIFAC by Yan et al. (1999 that we modified and reparametrised to better describe atmospherically relevant conditions and mixture compositions. Focusing on atmospheric applications we considered H^{+}, Li^{+}, Na^{+}, K^{+}, NH^{+}_{4}, Mg^{2+}, Ca^{2+}, Cl^{−}, Br^{−}, NO^{−}_{3}, HSO^{−}_{4}, and SO^{2−}_{4} as cations and anions and a wide range of alcohols/polyols composed of the functional groups CH_{n} and OH as organic compounds. With AIOMFAC, the activities of the components within an aqueous electrolyte solution are well represented up to high ionic strength. Most notably, a semi-empirical middle-range parametrisation of direct organic-inorganic interactions in alcohol+water+salt solutions strongly improves the agreement between experimental and modelled activity coefficients. At room temperature, this novel thermodynamic model offers the possibility to compute equilibrium relative humidities, gas/particle partitioning and liquid-liquid phase separations with high accuracy. In further studies, other organic functional groups will be introduced. The model framework is not restricted to specific ions or organic compounds and is therefore also
A thermodynamic model of mixed organic-inorganic aerosols to predict activity coefficients
Directory of Open Access Journals (Sweden)
A. Zuend
2008-03-01
Full Text Available Tropospheric aerosols contain mixtures of inorganic salts, acids, water, and a large variety of organic compounds. Interactions between these substances in liquid mixtures lead to discrepancies from ideal thermodynamic behaviour. By means of activity coefficients, non-ideal behaviour can be taken into account. We present here a thermodynamic model named AIOMFAC (Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients that is able to calculate activity coefficients covering inorganic, organic, and organic–inorganic interactions in aqueous solutions over a wide concentration range. This model is based on the activity coefficient model LIFAC by Yan et al. (1999 that we modified and reparametrised to better describe atmospherically relevant conditions and mixture compositions. Focusing on atmospheric applications we considered H^{+}, Li^{+}, Na^{+}, K^{+}, NH_{4}^{+}, Mg^{2+}, Ca^{2+}, Cl^{−}, Br^{−}, NO_{3}^{−}, HSO_{4}^{−}, and SO_{4}^{2−} as cations and anions and a wide range of alcohols/polyols composed of the functional groups CH_{n} and OH as organic compounds. With AIOMFAC, the activities of the components within an aqueous electrolyte solution are well represented up to high ionic strength. Most notably, a semi-empirical middle-range parametrisation of direct organic–inorganic interactions in alcohol + water + salt solutions strongly improves the agreement between experimental and modelled activity coefficients. At room temperature, this novel thermodynamic model offers the possibility to compute equilibrium relative humidities, gas/particle partitioning and liquid–liquid phase separations with high accuracy. In further studies, other organic functional groups will be introduced. The model framework is not restricted to specific ions or organic compounds and is therefore
A pandemic influenza modeling and visualization tool
Energy Technology Data Exchange (ETDEWEB)
Maciejewski, Ross; Livengood, Philip; Rudolph, Stephen; Collins, Timothy F.; Ebert, David S.; Brigantic, Robert T.; Corley, Courtney D.; Muller, George A.; Sanders, Stephen W.
2011-08-01
The National Strategy for Pandemic Influenza outlines a plan for community response to a potential pandemic. In this outline, state and local communities are charged with enhancing their preparedness. In order to help public health officials better understand these charges, we have developed a modeling and visualization toolkit (PanViz) for analyzing the effect of decision measures implemented during a simulated pandemic influenza scenario. Spread vectors based on the point of origin and distance traveled over time are calculated and the factors of age distribution and population density are taken into effect. Healthcare officials are able to explore the effects of the pandemic on the population through a spatiotemporal view, moving forward and backward through time and inserting decision points at various days to determine the impact. Linked statistical displays are also shown, providing county level summaries of data in terms of the number of sick, hospitalized and dead as a result of the outbreak. Currently, this tool has been deployed in Indiana State Department of Health planning and preparedness exercises, and as an educational tool for demonstrating the impact of social distancing strategies during the recent H1N1 (swine flu) outbreak.
Collaborative Inquiry Learning: Models, tools, and challenges
Bell, Thorsten; Urhahne, Detlef; Schanze, Sascha; Ploetzner, Rolf
2010-02-01
Collaborative inquiry learning is one of the most challenging and exciting ventures for today's schools. It aims at bringing a new and promising culture of teaching and learning into the classroom where students in groups engage in self-regulated learning activities supported by the teacher. It is expected that this way of learning fosters students' motivation and interest in science, that they learn to perform steps of inquiry similar to scientists and that they gain knowledge on scientific processes. Starting from general pedagogical reflections and science standards, the article reviews some prominent models of inquiry learning. This comparison results in a set of inquiry processes being the basis for cooperation in the scientific network NetCoIL. Inquiry learning is conceived in several ways with emphasis on different processes. For an illustration of the spectrum, some main conceptions of inquiry and their focuses are described. In the next step, the article describes exemplary computer tools and environments from within and outside the NetCoIL network that were designed to support processes of collaborative inquiry learning. These tools are analysed by describing their functionalities as well as effects on student learning known from the literature. The article closes with challenges for further developments elaborated by the NetCoIL network.
Beretta, Gian Paolo
2014-10-01
By suitable reformulations, we cast the mathematical frameworks of several well-known different approaches to the description of nonequilibrium dynamics into a unified formulation valid in all these contexts, which extends to such frameworks the concept of steepest entropy ascent (SEA) dynamics introduced by the present author in previous works on quantum thermodynamics. Actually, the present formulation constitutes a generalization also for the quantum thermodynamics framework. The analysis emphasizes that in the SEA modeling principle a key role is played by the geometrical metric with respect to which to measure the length of a trajectory in state space. In the near-thermodynamic-equilibrium limit, the metric tensor is directly related to the Onsager's generalized resistivity tensor. Therefore, through the identification of a suitable metric field which generalizes the Onsager generalized resistance to the arbitrarily far-nonequilibrium domain, most of the existing theories of nonequilibrium thermodynamics can be cast in such a way that the state exhibits the spontaneous tendency to evolve in state space along the path of SEA compatible with the conservation constraints and the boundary conditions. The resulting unified family of SEA dynamical models is intrinsically and strongly consistent with the second law of thermodynamics. The non-negativity of the entropy production is a general and readily proved feature of SEA dynamics. In several of the different approaches to nonequilibrium description we consider here, the SEA concept has not been investigated before. We believe it defines the precise meaning and the domain of general validity of the so-called maximum entropy production principle. Therefore, it is hoped that the present unifying approach may prove useful in providing a fresh basis for effective, thermodynamically consistent, numerical models and theoretical treatments of irreversible conservative relaxation towards equilibrium from far nonequilibrium
Experimental investigation and thermodynamic modeling of the Zr-Y system
Directory of Open Access Journals (Sweden)
Bu M.J.
2010-01-01
Full Text Available Based on the critical review of all the available experimental data in the literature, 8 key alloys were prepared by arc melting to investigate the phase equilibria in the Zr-Y system, These alloys, which were annealed at 5 different temperatures (800°C, 1000°C, 1100°C, 1120°C, 1160°C, were analyzed by means of X-ray diffraction, differential scanning calorimetry, optical microscopy and scanning electron microscopy with energy-dispersive X-ray spectroscopy. The results showed that a peritectoid reaction (βZr + (αY = (αZr occurs at 886°C ± 5°C, and an eutectic reaction L = (βZr + (αY occurs at 1313°C ± 5°C. Taking into account the experimental data obtained both from this work and the literature, the Zr-Y system was thermodynamically modeled. The previously reported temperature for the peritectic reaction of (βY + L = (αY at about 1490 °C is supported by our thermodynamic calculation. Comparison between the calculated and measured phase diagrams shows that the thermodynamic calculation can well account for the experimental data.
Harrold, Z.; Hertel, M.; Gorman-Lewis, D.
2012-12-01
Dissolved uranium speciation, mobility, and remediation are increasingly important topics given continued and potential uranium (U) release from mining operations and nuclear waste. Vegetative bacterial cell surfaces are known to adsorb uranium and may influence uranium speciation in the environment. Previous investigations regarding U(VI) adsorption to bacterial spores, a differentiated and dormant cell type with a tough proteinaceous coat, include U adsorption affinity and XAFS data. We investigated the thermodynamic stability of aerobic, pH dependent uranium adsorption to bacterial spore surfaces using purified Bacillus subtilis spores in solution with 5ppm uranium. Adsorption reversibility and kinetic experiments indicate that uranium does not precipitate over the duration of the experiments and equilibrium is reached within 20 minutes. Uranium-spore adsorption edges exhibited adsorption at all pH measured between 2 and 10. Maximum adsorption was achieved around pH 7 and decreased as pH increased above 7. We used surface complexation modeling (SCM) to quantify uranium adsorption based on balanced chemical equations and derive thermodynamic stability constants for discrete uranium-spore adsorption reactions. Site specific thermodynamic stability constants provide insight on interactions occurring between aqueous uranium species and spore surface ligands. The uranium adsorption data and SCM parameters described herein, also provide a basis for predicting the influence of bacterial spores on uranium speciation in natural systems and investigating their potential as biosorption agents in engineered systems.
Tušek, Jaka; Engelbrecht, Kurt; Mañosa, Lluis; Vives, Eduard; Pryds, Nini
2016-12-01
This paper presents direct and indirect methods for studying the elastocaloric effect (eCE) in shape memory materials and its comparison. The eCE can be characterized by the adiabatic temperature change or the isothermal entropy change (both as a function of applied stress/strain). To get these quantities, the evaluation of the eCE can be done using either direct methods, where one measures (adiabatic) temperature changes or indirect methods where one can measure the stress-strain-temperature characteristics of the materials and from these deduce the adiabatic temperature and isothermal entropy changes. The former can be done using the basic thermodynamic relations, i.e. Maxwell relation and Clausius-Clapeyron equation. This paper further presents basic thermodynamic properties of shape memory materials, such as the adiabatic temperature change, isothermal entropy change and total entropy-temperature diagrams (all as a function of temperature and applied stress/strain) of two groups of materials (Ni-Ti and Cu-Zn-Al alloys) obtained using indirect methods through phenomenological modelling and Maxwell relation. In the last part of the paper, the basic definition of the efficiency of the elastocaloric thermodynamic cycle (coefficient of performance) is defined and discussed.
McDougall, Trevor
2010-05-01
The Intergovernmental Oceanographic Commission (IOC) has endorsed a new equation of state of seawater to replace the International Equation of State of 1980. The new Thermodynamic Equation of Seawater 2010 (TEOS-10 for short) has been prepared by SCOR/IAPSO Working Group 127, and from 1st January 2010, is the new worldwide standard description of seawater. This thermodynamic description of seawater provides accurate algorithms for Absolute Salinity, density, entropy, enthalpy and many other properties. The software of the new seawater standard is available on line from www.TEOS-10.org. The talk will concentrate on three main topics, namely (i) the definition and use of a new form of salinity called Absolute Salinity which takes into account the spatial variation in the composition of seawater, (ii) a thermodynamic variable that can be used to accurately represent the transport and mixing of "heat" in the ocean, and (iii) the differences between the specific volume of TEOS-10 and that of EOS-80 (the International Equation of State of seawater that has been in use since 1980). The talk will discuss the relative improvements in the accuracy of observational oceanography and ocean models that can be expected from adopting TEOS-10.
Thermodynamic modeling and experimental investigation of the magnesium–zinc–samarium alloys
Energy Technology Data Exchange (ETDEWEB)
Xia, Xiangyu, E-mail: xxia5@wisc.edu [Materials Science Program, University of Wisconsin – Madison, 1509 University Ave., Madison, WI 53706 (United States); Department of Materials Science and Engineering, University of Wisconsin – Madison, 1509 University Ave., Madison, WI 53706 (United States); Sanaty-Zadeh, Amirreza [Materials Science Program, University of Wisconsin – Madison, 1509 University Ave., Madison, WI 53706 (United States); Department of Materials Science and Engineering, University of Wisconsin – Madison, 1509 University Ave., Madison, WI 53706 (United States); Zhang, Chuan [Computherm LLC, 437 S. Yellowstone Dr., Suite217, Madison, WI 53719 (United States); Luo, Alan A. [Department of Materials Science and Engineering, University of Wisconsin – Madison, 1509 University Ave., Madison, WI 53706 (United States); Department of Materials Science and Engineering, The Ohio State University, 116 W. 19th Ave., Columbus, OH 43210 (United States); Zeng, Xiaoqin [Department of Materials Science and Engineering, Shanghai Jiaotong University, 800, Dongchuan Road, Shanghai (China); Austin Chang, Y.; Stone, Donald S. [Materials Science Program, University of Wisconsin – Madison, 1509 University Ave., Madison, WI 53706 (United States); Department of Materials Science and Engineering, University of Wisconsin – Madison, 1509 University Ave., Madison, WI 53706 (United States)
2014-04-01
Highlights: • Ternary phases in Mg–Zn–Sm alloy system were experimentally determined. • One previously-reported ternary phase is determined as Mg{sub 3}Sm binary phase. • Phase relationships of Mg–Zn–Sm system near Mg corner are obtained experimentally. • A thermodynamic description of this system was developed using CALPHAD method. - Abstract: Magnesium (Mg)–Zinc (Zn)–Samarium (Sm) alloy system is being considered for the development of high-strength novel Mg alloys for structural applications. In this work, ternary phases in Mg–Zn–Sm system at Mg-rich corner were identified experimentally, based upon the investigation of five key alloys. Phase relationships at 350, 400 and 450 °C of this system were also established. Furthermore, a self-consistent thermodynamic description of Mg–Zn–Sm system at Mg-rich corner was developed for the first time using the CALPHAD (CALculation of PHAse Diagram) method. Good agreement between the calculated phase diagrams and the experimentally measured data from both this study and literature validated the thermodynamic modeling approach used in this work.
Vrabec, Jadran; Kedia, Gaurav Kumar; Buchhauser, Ulrich; Meyer-Pittroff, Roland; Hasse, Hans
2009-02-01
For the design and optimization of CO 2 recovery from alcoholic fermentation processes by distillation, models for vapor-liquid equilibria (VLE) are needed. Two such thermodynamic models, the Peng-Robinson equation of state (EOS) and a model based on Henry's law constants, are proposed for the ternary mixture N 2 + O 2 + CO 2. Pure substance parameters of the Peng-Robinson EOS are taken from the literature, whereas the binary parameters of the Van der Waals one-fluid mixing rule are adjusted to experimental binary VLE data. The Peng-Robinson EOS describes both binary and ternary experimental data well, except at high pressures approaching the critical region. A molecular model is validated by simulation using binary and ternary experimental VLE data. On the basis of this model, the Henry's law constants of N 2 and O 2 in CO 2 are predicted by molecular simulation. An easy-to-use thermodynamic model, based on those Henry's law constants, is developed to reliably describe the VLE in the CO 2-rich region.
Thermodynamic Model and Database for Sulfides Dissolved in Molten Oxide Slags
Kang, Youn-Bae; Pelton, Arthur D.
2009-12-01
A thermodynamic model has been developed in the framework of the modified quasichemical model in the quadruplet approximation to permit the calculation of solubilities of various gaseous species (sulfide, sulfate, nitride, carbide, water, etc.) in molten slags. The model calculates the solubilities solely from knowledge of the thermodynamic activities of the component oxides and the Gibbs energies of the pure liquid components (oxides, sulfides, sulfates, etc.). In the current article, it is shown that solubilities of sulfur as sulfide in Al2O3-CaO-FeO-Fe2O3-MgO-MnO-SiO2-TiO2-Ti2O3 multicomponent slags, which are predicted from the current model with no adjustable model parameters, are in good agreement with all available experimental data. The article also provides a thorough review of experimental sulfide capacity data for this system. The model applies at all compositions from pure oxides to pure sulfides and from basic to acidic slags. By coupling this database with other evaluated databases, such as those for molten metal and gaseous phases, and with general software for Gibbs energy minimization, practically important slag/metal/gas/solid equilibria can be computed such as S-distribution ratios.
Thermodynamic forward modeling of retrogressive hydration reactions induced by geofluid infiltration
Kuwatani, Tatsu; Toriumi, Mitsuhiro
2017-01-01
We have developed a new methodology for forward analysis of retrogressive hydration (rehydration) reactions by an improved thermodynamic forward modeling technique based on a differential thermodynamic approach (Gibbs' method). Based on natural observations and theoretical considerations, the progress of a rehydration reaction is modeled by incorporating a change in the effective bulk composition on account of the breakdown of the non-equilibrated phase and the amount of water infiltration into the system. Forward analyses of rehydration reactions under greenschist-facies conditions show that (1) the reaction progress of rehydration is proportional to the external water supply, and (2) the mineral compositions of equilibrated minerals are mainly controlled by P- T conditions and are similar to those in the global equilibrium model. Calculated results are in accordance with natural observations of rehydration reactions in greenschist-facies rocks, which supports the validity of the proposed model. The proposed model can be used as a basic forward model for various inversion analyses and numerical simulations and thus to understand the distribution and behavior of geofluids.[Figure not available: see fulltext.
Vrabec, J; Buchhauser, U; Meyer-Pittroff, R; Hasse, H
2009-01-01
For the design and optimization of CO2 recovery from alcoholic fermentation processes by distillation, models for vapor-liquid equilibria (VLE) are needed. Two such thermodynamic models, the Peng-Robinson equation of state (EOS) and a model based on Henry's law constants, are proposed for the ternary mixture N2+O2+CO2. Pure substance parameters of the Peng-Robinson EOS are taken from the literature, whereas the binary parameters of the Van der Waals one-fluid mixing rule are adjusted to experimental binary VLE data. The Peng-Robinson EOS describes both binary and ternary experimental data well, except at high pressures approaching the critical region. A molecular model is validated by simulation using binary and ternary experimental VLE data. On the basis of this model, the Henry's law constants of N2 and O2 in CO2 are predicted by molecular simulation. An easy-to-use thermodynamic model, based on those Henry's law constants, is developed to reliably describe the VLE in the CO2-rich region.
Hess, Julian; Wang, Yongqi
2016-11-01
A new mixture model for granular-fluid flows, which is thermodynamically consistent with the entropy principle, is presented. The extra pore pressure described by a pressure diffusion equation and the hypoplastic material behavior obeying a transport equation are taken into account. The model is applied to granular-fluid flows, using a closing assumption in conjunction with the dynamic fluid pressure to describe the pressure-like residual unknowns, hereby overcoming previous uncertainties in the modeling process. Besides the thermodynamically consistent modeling, numerical simulations are carried out and demonstrate physically reasonable results, including simple shear flow in order to investigate the vertical distribution of the physical quantities, and a mixture flow down an inclined plane by means of the depth-integrated model. Results presented give insight in the ability of the deduced model to capture the key characteristics of granular-fluid flows. We acknowledge the support of the Deutsche Forschungsgemeinschaft (DFG) for this work within the Project Number WA 2610/3-1.
Eichhorn, Ralf; Aurell, Erik
2014-04-01
'Stochastic thermodynamics as a conceptual framework combines the stochastic energetics approach introduced a decade ago by Sekimoto [1] with the idea that entropy can consistently be assigned to a single fluctuating trajectory [2]'. This quote, taken from Udo Seifert's [3] 2008 review, nicely summarizes the basic ideas behind stochastic thermodynamics: for small systems, driven by external forces and in contact with a heat bath at a well-defined temperature, stochastic energetics [4] defines the exchanged work and heat along a single fluctuating trajectory and connects them to changes in the internal (system) energy by an energy balance analogous to the first law of thermodynamics. Additionally, providing a consistent definition of trajectory-wise entropy production gives rise to second-law-like relations and forms the basis for a 'stochastic thermodynamics' along individual fluctuating trajectories. In order to construct meaningful concepts of work, heat and entropy production for single trajectories, their definitions are based on the stochastic equations of motion modeling the physical system of interest. Because of this, they are valid even for systems that are prevented from equilibrating with the thermal environment by external driving forces (or other sources of non-equilibrium). In that way, the central notions of equilibrium thermodynamics, such as heat, work and entropy, are consistently extended to the non-equilibrium realm. In the (non-equilibrium) ensemble, the trajectory-wise quantities acquire distributions. General statements derived within stochastic thermodynamics typically refer to properties of these distributions, and are valid in the non-equilibrium regime even beyond the linear response. The extension of statistical mechanics and of exact thermodynamic statements to the non-equilibrium realm has been discussed from the early days of statistical mechanics more than 100 years ago. This debate culminated in the development of linear response
Evaluation of clinical information modeling tools.
Moreno-Conde, Alberto; Austin, Tony; Moreno-Conde, Jesús; Parra-Calderón, Carlos L; Kalra, Dipak
2016-11-01
Clinical information models are formal specifications for representing the structure and semantics of the clinical content within electronic health record systems. This research aims to define, test, and validate evaluation metrics for software tools designed to support the processes associated with the definition, management, and implementation of these models. The proposed framework builds on previous research that focused on obtaining agreement on the essential requirements in this area. A set of 50 conformance criteria were defined based on the 20 functional requirements agreed by that consensus and applied to evaluate the currently available tools. Of the 11 initiative developing tools for clinical information modeling identified, 9 were evaluated according to their performance on the evaluation metrics. Results show that functionalities related to management of data types, specifications, metadata, and terminology or ontology bindings have a good level of adoption. Improvements can be made in other areas focused on information modeling and associated processes. Other criteria related to displaying semantic relationships between concepts and communication with terminology servers had low levels of adoption. The proposed evaluation metrics were successfully tested and validated against a representative sample of existing tools. The results identify the need to improve tool support for information modeling and software development processes, especially in those areas related to governance, clinician involvement, and optimizing the technical validation of testing processes. This research confirmed the potential of these evaluation metrics to support decision makers in identifying the most appropriate tool for their organization. Los Modelos de Información Clínica son especificaciones para representar la estructura y características semánticas del contenido clínico en los sistemas de Historia Clínica Electrónica. Esta investigación define, prueba y valida
A set of molecular models based on quantum mechanical ab initio calculations and thermodynamic data
Eckl, Bernhard; Hasse, Hans
2009-01-01
A parameterization strategy for molecular models on the basis of force fields is proposed, which allows a rapid development of models for small molecules by using results from quantum mechanical (QM) ab initio calculations and thermodynamic data. The geometry of the molecular models is specified according to the atom positions determined by QM energy minimization. The electrostatic interactions are modeled by reducing the electron density distribution to point dipoles and point quadrupoles located in the center of mass of the molecules. Dispersive and repulsive interactions are described by Lennard-Jones sites, for which the parameters are iteratively optimized to experimental vapor-liquid equilibrium (VLE) data, i.e. vapor pressure, saturated liquid density, and enthalpy of vaporization of the considered substance. The proposed modeling strategy was applied to a sample set of ten molecules from different substance classes. New molecular models are presented for iso-butane, cyclohexane, formaldehyde, dimethyl...
Müller, W.; Alkan, H.; Xie, M.; Moog, H.; Sonnenthal, E. L.
2009-12-01
for both Pitzer ion-interaction parameters and thermodynamic equilibrium constants. The reliability of the parameters is as important as the accuracy of the modelling tool. For this purpose the project THEREDA (www.thereda.de)was set up. The project aims at a comprehensive and internally consistent thermodynamic reference database for geochemical modelling of near and far-field processes occurring in repositories for radioactive wastes in various host rock formations. In the framework of the project all data necessary to perform thermodynamic equilibrium calculations for elevated temperature in the system of oceanic salts are under revision, and it is expected that related data will be available for download by 2010-03. In this paper the geochemical issues that can play an essential role for the transport of radioactive contaminants within and around waste repositories are discussed. Some generic calculations are given to illustrate the geochemical interactions and their probable effects on the transport properties around HLW emplacements and on CO2 generating and/or containing repository systems.
A deformation and thermodynamic model for hydride precipitation kinetics in spent fuel cladding
Energy Technology Data Exchange (ETDEWEB)
Stout, R.B.
1989-10-01
Hydrogen is contained in the Zircaloy cladding of spent fuel rods from nuclear reactors. All the spent fuel rods placed in a nuclear waste repository will have a temperature history that decreases toward ambient; and as a result, most all of the hydrogen in the Zircaloy will eventually precipitate as zirconium hydride platelets. A model for the density of hydride platelets is a necessary sub-part for predicting Zircaloy cladding failure rate in a nuclear waste repository. A model is developed to describe statistically the hydride platelet density, and the density function includes the orientation as a physical attribute. The model applies concepts from statistical mechanics to derive probable deformation and thermodynamic functionals for cladding material response that depend explicitly on the hydride platelet density function. From this model, hydride precipitation kinetics depend on a thermodynamic potential for hydride density change and on the inner product of a stress tensor and a tensor measure for the incremental volume change due to hydride platelets. The development of a failure response model for Zircaloy cladding exposed to the expected conditions in a nuclear waste repository is supported by the US DOE Yucca Mountain Project. 19 refs., 3 figs.
Industrial-scale Fixed-bed Coal Gasification:Modeling, Simulation and Thermodynamic Analysis
Institute of Scientific and Technical Information of China (English)
何畅; 冯霄; 李安学; 刘永健
2014-01-01
We have developed a process model to simulate the behavior of an industrial-scale pressurized Lurgi fixed-bed coal gasifier using Aspen Plus and General Algebraic Modeling System (GAMS). Reaction characteristics in the fixed-bed gasifier comprising four sequential reaction zones-drying, pyrolysis, combustion and gasification are respectively modeled. A non-linear programming (NLP) model is developed for the pyrolysis zone to estimate the products composition which includes char, coal gases and distillable liquids. A four-stage model with restricted equilibrium temperature is used to study the thermodynamic equilibrium characteristics and calculate the composi-tion of syngas in the combustion and gasification zones. The thermodynamic analysis shows that the exergetic effi-ciency of the fixed-bed gasifier is mainly determined by the oxygen/coal ratio. The exergetic efficiency of the proc-ess will reach an optimum value of 78.3%when the oxygen/coal and steam/coal mass ratios are 0.14 and 0.80, re-spectively.
Thermodynamic modeling of Al–U–X (X = Si,Zr)
Energy Technology Data Exchange (ETDEWEB)
Rabin, Daniel; Shneck, Roni Z. [Department of Materials Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105 (Israel); Rafailov, Gennady [Department of Materials Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105 (Israel); NRCN, P.O. Box 9001, Beer-Sheva 84190 (Israel); Dahan, Isaac [NRCN, P.O. Box 9001, Beer-Sheva 84190 (Israel); Meshi, Louisa [Department of Materials Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105 (Israel); Brosh, Eli, E-mail: ebrosh1@gmail.com [NRCN, P.O. Box 9001, Beer-Sheva 84190 (Israel)
2015-09-15
Highlights: • Thermodynamic models of the U–Al–Si and U–Al–Zr systems were constructed. • The extrapolation methods of the ternary liquid phase were explored. • The order–disorder transition of the U(Al,Si){sub 3} phase was modeled. • New experiments fix the composition of U(Al,Si){sub 3} in equilibrium with Al and Si. • Effects of Si on microstructures of solidified U–Al alloys are clarified. - Abstract: Thermodynamic models are constructed for the U–Al–Si and U–A–Zr ternary alloy systems using the CALPHAD (CALculation of PHAse Diagrams) method. For the U–Al–Zr system the modeling covers only the aluminum-rich corner (from 100 at% to 67 at% Al) and is based only on literature data. For the U–Al–Si system, the whole range of compositions is covered and new key experiments were done in the uranium-poor region of the U–Al–Si system. These experiments have shown that under conditions of equilibrium with Al and Si, the Si-content of the U(Al,Si){sub 3} is significantly higher than reported by earlier works. Different extrapolation methods were tried for the Gibbs energy of the liquid phase. However, it was found that for the U–Al–Si and U–Al–Zr systems, symmetric Muggianu method and the asymmetric method by Hillert give similar predictions. The constructed thermodynamic database was investigated by calculating isothermal sections, vertical sections and the liquidus projection. The calculated diagrams are in reasonable agreement with experimental data. Finally, solidification simulation (Scheil simulation) was done in order to assess the phases obtained in solidification as a function of the silicon addition to U–Al alloys.
Thermodynamic modeling of the La-Mg-Y system and Mg-based alloys database
Institute of Scientific and Technical Information of China (English)
DU Zhenmin; GUO Cuiping; LI Changrong; ZHANG Weijing
2006-01-01
As an example of the La-Mg-Y system, the method how to set up the thermodynamic model of individual phases was introduced in the process of thermodynamic optimization. The solution phases (liquid, body-centered cubic,face-centered cubic, hexagonal close-packed and double hexagonal close-packed) were modeled with the Redlich-Kister equation. The compound energy model has been used to describe the thermodynamic functions of the intermetallic compounds in the La-Mg-Y systems. The compounds Mg2Y, Mg24Y5, Mg12La, Mg17La2, Mg41La5, Mg3La and Mg2La in the La-Mg-Y system were treated as the formulae (Mg, Y)2(La,Mg, Y), Mg24(La,Mg, Y)4Y, Mg12(La, Y), Mg17(La, Y)2,Mg41(La,Y)5, Mg3(La,Mg,Y) and Mg2(La,Y), respectively. A model (La,Mg,Y)0.5(La,Mg,Y)0.5 was applied to describe the compound MgM formed by MgLa and MgY in order to cope with the order-disorder transition between body-centered cubic solution (A2) and MgM with CsCl-type structure (B2) in the La-Mg-Y system. The Gibbs energies of individual phases were optimized in the La-Mg, La-Y and La-Mg-Y systems by CALPHAD technique. The projection of the liquidus surfaces for the La-Mg-Y system was predicted. The Mg-based alloys database including 36 binary and 15 ternary systems formed by Mg, Al, Cu, Ni, Mn, Zn and rare earth elements was set up in SGTE standard.
A thermodynamically consistent model of the post-translational Kai circadian clock
Lubensky, David K.; ten Wolde, Pieter Rein
2017-01-01
The principal pacemaker of the circadian clock of the cyanobacterium S. elongatus is a protein phosphorylation cycle consisting of three proteins, KaiA, KaiB and KaiC. KaiC forms a homohexamer, with each monomer consisting of two domains, CI and CII. Both domains can bind and hydrolyze ATP, but only the CII domain can be phosphorylated, at two residues, in a well-defined sequence. While this system has been studied extensively, how the clock is driven thermodynamically has remained elusive. Inspired by recent experimental observations and building on ideas from previous mathematical models, we present a new, thermodynamically consistent, statistical-mechanical model of the clock. At its heart are two main ideas: i) ATP hydrolysis in the CI domain provides the thermodynamic driving force for the clock, switching KaiC between an active conformational state in which its phosphorylation level tends to rise and an inactive one in which it tends to fall; ii) phosphorylation of the CII domain provides the timer for the hydrolysis in the CI domain. The model also naturally explains how KaiA, by acting as a nucleotide exchange factor, can stimulate phosphorylation of KaiC, and how the differential affinity of KaiA for the different KaiC phosphoforms generates the characteristic temporal order of KaiC phosphorylation. As the phosphorylation level in the CII domain rises, the release of ADP from CI slows down, making the inactive conformational state of KaiC more stable. In the inactive state, KaiC binds KaiB, which not only stabilizes this state further, but also leads to the sequestration of KaiA, and hence to KaiC dephosphorylation. Using a dedicated kinetic Monte Carlo algorithm, which makes it possible to efficiently simulate this system consisting of more than a billion reactions, we show that the model can describe a wealth of experimental data. PMID:28296888
DATA QUALITY TOOLS FOR DATAWAREHOUSE MODELS
Directory of Open Access Journals (Sweden)
JASPREETI SINGH
2015-05-01
Full Text Available Data quality tools aim at detecting and correcting data problems that influence the accuracy and efficiency of data analysis applications. Data warehousing activities require data quality tools to ready the data and ensure that clean data populates the warehouse, thus raising usability of the warehouse. This research targets on the problems in the data that are addressed by data quality tools. We classify data quality tools based on datawarehouse stages and features of tool; which address the data quality problems and understand their functionalities.
Thermodynamic re-modelling of the ternary Al–Cr–Ti system with refined Al–Cr description
Energy Technology Data Exchange (ETDEWEB)
Witusiewicz, V.T., E-mail: v.vitusevych@access-technology.de [ACCESSe.V., Intzestr. 5, D-52072 Aachen (Germany); Bondar, A.A. [Frantsevich Institute for Problems of Materials Science, Krzhyzhanovsky Str. 3, 03680 Kyiv (Ukraine); Hecht, U. [ACCESSe.V., Intzestr. 5, D-52072 Aachen (Germany); Velikanova, T.Ya. [Frantsevich Institute for Problems of Materials Science, Krzhyzhanovsky Str. 3, 03680 Kyiv (Ukraine)
2015-09-25
Highlights: • Thermodynamic refinement of the Al–Cr system. • Key experimental investigations of the ternary Al–Cr–Ti alloys. • Thermodynamic modelling of the complete Al–Cr–Ti system. - Abstract: In the present paper, the ternary Al–Cr–Ti and binary constituent Al–Cr systems are thermodynamically re-modelled based on new experimental information reported in the literature within the past few years. Few key experiments were performed with selected ternary alloys in order to complement data on phase equilibria in the composition range of common TiAl-based alloys. Six sample compositions were prepared and analyzed in the as-cast and annealed conditions by means of SEM/EDS, XRD and DTA techniques. The elaborated thermodynamic description was applied to calculate selected phase equilibria as to provide a comparison between calculated and experimental results. The calculations are shown to reproduce the experimental data reasonably well.
Methods to Increase the Robustness of Finite-Volume Flow Models in Thermodynamic Systems
Directory of Open Access Journals (Sweden)
Sylvain Quoilin
2014-03-01
Full Text Available This paper addresses the issues linked to simulation failures during integration in finite-volume flow models, especially those involving a two-phase state. This kind of model is particularly useful when modeling 1D heat exchangers or piping, e.g., in thermodynamic cycles involving a phase change. Issues, such as chattering or stiff systems, can lead to low simulation speed, instabilities and simulation failures. In the particular case of two-phase flow models, they are usually linked to a discontinuity in the density derivative between the liquid and two-phase zones. In this work, several methods to tackle numerical problems are developed, described, implemented and compared. In addition, methods available in the literature are also implemented and compared to the proposed approaches. Results suggest that the robustness of the models can be significantly increased with these different methods, at the price of a small increase of the error in the mass and energy balances.
Institute of Scientific and Technical Information of China (English)
PallabGhosh
2003-01-01
Nanofiltration separation has become a popular technique for removing large organic molecules and inorganic substances from water. It is achieved by a combination of three mechanisms: electrostatic repulsion,sieving and diffusion. In the present work, a model based on irreversible thermodynamics is extended and used to estimate rejection of inorganic salts and organic substances. Binary systems are modeled, where the feed contains an ion that is much less permeable to the membrane as compared with the other ion. The two model parameters are estimated by fitting the model to the experimental data. Variation of these parameters with the composition of the feed is described by an empirical correlation. This work attempts to describe transport through the nanofiltration membranes bv a simple model.
Resolution of conflicting views on thermodynamics of glass transition: A unified model
Indian Academy of Sciences (India)
K T Jacob; Sagar Prabhudev; R M Mallya
2010-10-01
Classical description of thermodynamic properties during glass transition has been questioned by the entropy-loss model. The uncompensated loss of entropy at the glass transition temperature and zero residual entropy is at the heart of the controversy. Both the models are critically reviewed. A unified model is presented which incorporates features of both entropy loss and residual entropy. It implies two different types of contributions to the entropy of the supercooled liquid, one of which vanishes at the transition and the other which contributes to residual entropy. Entropy gain during spontaneous relaxation of glass, and the nature of heat capacity ‘hysteresis’ during cooling and heating through the glass transition range support the proposed model. Experiments are outlined for differentiating between the models.
A molecular thermodynamic model for the stability of hepatitis B capsids
Energy Technology Data Exchange (ETDEWEB)
Kim, Jehoon; Wu, Jianzhong, E-mail: jwu@engr.ucr.edu [Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521 (United States)
2014-06-21
Self-assembly of capsid proteins and genome encapsidation are two critical steps in the life cycle of most plant and animal viruses. A theoretical description of such processes from a physiochemical perspective may help better understand viral replication and morphogenesis thus provide fresh insights into the experimental studies of antiviral strategies. In this work, we propose a molecular thermodynamic model for predicting the stability of Hepatitis B virus (HBV) capsids either with or without loading nucleic materials. With the key components represented by coarse-grained thermodynamic models, the theoretical predictions are in excellent agreement with experimental data for the formation free energies of empty T4 capsids over a broad range of temperature and ion concentrations. The theoretical model predicts T3/T4 dimorphism also in good agreement with the capsid formation at in vivo and in vitro conditions. In addition, we have studied the stability of the viral particles in response to physiological cellular conditions with the explicit consideration of the hydrophobic association of capsid subunits, electrostatic interactions, molecular excluded volume effects, entropy of mixing, and conformational changes of the biomolecular species. The course-grained model captures the essential features of the HBV nucleocapsid stability revealed by recent experiments.
Modeling Xenon Tank Pressurization using One-Dimensional Thermodynamic and Heat Transfer Equations
Gilligan, Ryan P.; Tomsik, Thomas M.
2017-01-01
As a first step in understanding what ground support equipment (GSE) is required to provide external cooling during the loading of 5,000 kg of xenon into 4 aluminum lined composite overwrapped pressure vessels (COPVs), a modeling analysis was performed using Microsoft Excel. The goals of the analysis were to predict xenon temperature and pressure throughout loading at the launch facility, estimate the time required to load one tank, and to get an early estimate of what provisions for cooling xenon might be needed while the tanks are being filled. The model uses the governing thermodynamic and heat transfer equations to achieve these goals. Results indicate that a single tank can be loaded in about 15 hours with reasonable external coolant requirements. The model developed in this study was successfully validated against flight and test data. The first data set is from the Dawn mission which also utilizes solar electric propulsion with xenon propellant, and the second is test data from the rapid loading of a hydrogen cylindrical COPV. The main benefit of this type of model is that the governing physical equations using bulk fluid solid temperatures can provide a quick and accurate estimate of the state of the propellant throughout loading which is much cheaper in terms of computational time and licensing costs than a Computation Fluid Dynamics (CFD) analysis while capturing the majority of the thermodynamics and heat transfer.
A molecular thermodynamic model for the stability of hepatitis B capsids
Kim, Jehoon; Wu, Jianzhong
2014-06-01
Self-assembly of capsid proteins and genome encapsidation are two critical steps in the life cycle of most plant and animal viruses. A theoretical description of such processes from a physiochemical perspective may help better understand viral replication and morphogenesis thus provide fresh insights into the experimental studies of antiviral strategies. In this work, we propose a molecular thermodynamic model for predicting the stability of Hepatitis B virus (HBV) capsids either with or without loading nucleic materials. With the key components represented by coarse-grained thermodynamic models, the theoretical predictions are in excellent agreement with experimental data for the formation free energies of empty T4 capsids over a broad range of temperature and ion concentrations. The theoretical model predicts T3/T4 dimorphism also in good agreement with the capsid formation at in vivo and in vitro conditions. In addition, we have studied the stability of the viral particles in response to physiological cellular conditions with the explicit consideration of the hydrophobic association of capsid subunits, electrostatic interactions, molecular excluded volume effects, entropy of mixing, and conformational changes of the biomolecular species. The course-grained model captures the essential features of the HBV nucleocapsid stability revealed by recent experiments.
Thermodynamic database development-modeling and phase diagram calculations in oxide systems
Institute of Scientific and Technical Information of China (English)
Arthur D. Pelton
2006-01-01
The databases of the FactSage thermodynamic computer system have been under development for 30 years. These databases contain critically evaluated and optimized data for thousands of compounds and hundreds of multicomponent solutions of solid and liquid metals, oxides, salts, sulfides, etc. The databases are automatically accessed by user-friendly software that calculates complex multiphase equilibria in large multicomponent systems for a wide variety of possible input/output constraints. The databases for solutions have been developed by critical evaluation/optimization of all available phase equilibrium and thermodynamic data. The databases contain parameters of models specifically developed for different types of solutions involving sublattices, ordering, etc. Through the optimization process, model parameters are found which reproduce all thermodynamic and phase equilibrium data within experimental error limits and permit extrapolation into regions of temperature and composition where data are unavailable. The present article focuses on the databases for solid and liquid oxide phases involving 25 elements. A short review of the available databases is presented along with the models used for the molten slag and the solid solutions such as spinel, pyroxene, olivine, monoxide, corundum, etc. The critical evaluation/optimization procedure is outlined using examples from the A12O3-SiO2-CaO-FeO-Fe2O3 system. Sample calculations are presented in which the oxide databases are used in conjunction with the FactSage databases for metallic and other phases. In particular, the use of the FactSage module for the calculation of multicomponent phase diagrams is illustrated.
An Irreversible Thermodynamics Model for Graphite Sublimation in Intense Radiation Environments.
1980-09-15
AD-AOG9 405 AEROSPACE CORP EL SEGUNDO CA VEHICLE ENGINEERING DIV F/IG 7/4 AN IRREVERSIBLE THERMODYNAMICS MODEL FOR GRAPHITE SUBLIMATION I--ETC(U) SEP...approved for The Aerospace Corporation by E. G. Hertler of the Vehicle Engineering Division and W. P. Thompson of the Space Plans Directorate. The Air Force...reason for this nonuniqueness is illustrated in Fig. 3. The sum of the species partial pressures and the sum of the species vapor pressures are shown
Thermodiffusion in Multicomponent Mixtures Thermodynamic, Algebraic, and Neuro-Computing Models
Srinivasan, Seshasai
2013-01-01
Thermodiffusion in Multicomponent Mixtures presents the computational approaches that are employed in the study of thermodiffusion in various types of mixtures, namely, hydrocarbons, polymers, water-alcohol, molten metals, and so forth. We present a detailed formalism of these methods that are based on non-equilibrium thermodynamics or algebraic correlations or principles of the artificial neural network. The book will serve as single complete reference to understand the theoretical derivations of thermodiffusion models and its application to different types of multi-component mixtures. An exhaustive discussion of these is used to give a complete perspective of the principles and the key factors that govern the thermodiffusion process.
A reduced thermodynamic model on the formation of the Nansha warm water
Institute of Scientific and Technical Information of China (English)
CAI Shuqun; GAN Zijun; LI Chiwai; LONG Xiaomin; DONG Danpeng
2004-01-01
A reduced vertically integrated upper mixed layer model is set up to numerically study the thermodynamic process of the formation of the "Nansha warm water"(NWW) in the Nansha Islands sea areas in spring. According to the numerical experiments, it is shown that, in spring, the formation of the NWW is mainly due to the sea surface net heat flux and the local weak current strength; the contribution from temperature advection transport and warm water exchange with the outer seas (Sulu Sea or south of Sunda shelf) is very little. In the sea areas where the current is strong, the advection may also play an important role in the temperature field.
Energy Technology Data Exchange (ETDEWEB)
Gonzalez-Perez, Alfredo [Group of Biophysics and Interfaces, Department of Applied Physics, Faculty of Physics, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain)], E-mail: alf@usc.es; Ruso, Juan M. [Group of Biophysics and Interfaces, Department of Applied Physics, Faculty of Physics, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Romero, Maria J. [Department of Inorganic Chemistry, Faculty of Chemistry, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Blanco, Elena [Group of Biophysics and Interfaces, Department of Applied Physics, Faculty of Physics, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Prieto, Gerardo [Group of Biophysics and Interfaces, Department of Applied Physics, Faculty of Physics, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Sarmiento, Felix [Group of Biophysics and Interfaces, Department of Applied Physics, Faculty of Physics, University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain)
2005-06-27
Sodium perfluoroalkyl carboxylates (CnFONa) with n = 6, 9, 10 have been studied by conductivity measurements at different temperatures. The Krafft point was determined for C9FONa and C10FONa at the highest concentration studied by measuring the temperature dependence of the specific conductivity. The critical micelle concentration (cmc) and the ionization degree of the micelle ({beta}) were estimated from conductivity vs. molality plots at different temperatures. Using these data and previous results on temperature dependence of cmc and {beta} of sodium perfluoroheptanoate and perfluorooctanoate, different models were applied to obtain the thermodynamic properties of micellization. The results are discussed in terms of alkyl chain length.
General model for boring tool optimization
Moraru, G. M.; rbes, M. V. Ze; Popescu, L. G.
2016-08-01
Optimizing a tool (and therefore those for boring) consist in improving its performance through maximizing the objective functions chosen by the designer and/or by user. In order to define and to implement the proposed objective functions, contribute numerous features and performance required by tool users. Incorporation of new features makes the cutting tool to be competitive in the market and to meet user requirements.
Models and Modelling Tools for Chemical Product and Process Design
DEFF Research Database (Denmark)
Gani, Rafiqul
2016-01-01
The design, development and reliability of a chemical product and the process to manufacture it, need to be consistent with the end-use characteristics of the desired product. One of the common ways to match the desired product-process characteristics is through trial and error based experiments......-based framework is that in the design, development and/or manufacturing of a chemical product-process, the knowledge of the applied phenomena together with the product-process design details can be provided with diverse degrees of abstractions and details. This would allow the experimental resources......, are the needed models for such a framework available? Or, are modelling tools that can help to develop the needed models available? Can such a model-based framework provide the needed model-based work-flows matching the requirements of the specific chemical product-process design problems? What types of models...
Kou, Jisheng
2016-01-01
A general diffuse interface model with a realistic equation of state (e.g. Peng-Robinson equation of state) is proposed to describe the multi-component two-phase fluid flow based on the principles of the NVT-based framework which is a latest alternative over the NPT-based framework to model the realistic fluids. The proposed model uses the Helmholtz free energy rather than Gibbs free energy in the NPT-based framework. Different from the classical routines, we combine the first law of thermodynamics and related thermodynamical relations to derive the entropy balance equation, and then we derive a transport equation of the Helmholtz free energy density. Furthermore, by using the second law of thermodynamics, we derive a set of unified equations for both interfaces and bulk phases that can describe the partial miscibility of two fluids. A relation between the pressure gradient and chemical potential gradients is established, and this relation leads to a new formulation of the momentum balance equation, which dem...
Tomar, Dheeraj S; Weber, Valéry; Pettitt, B Montgomery; Asthagiri, D
2014-04-17
The hydration thermodynamics of the amino acid X relative to the reference G (glycine) or the hydration thermodynamics of a small-molecule analog of the side chain of X is often used to model the contribution of X to protein stability and solution thermodynamics. We consider the reasons for successes and limitations of this approach by calculating and comparing the conditional excess free energy, enthalpy, and entropy of hydration of the isoleucine side chain in zwitterionic isoleucine, in extended penta-peptides, and in helical deca-peptides. Butane in gauche conformation serves as a small-molecule analog for the isoleucine side chain. Parsing the hydrophobic and hydrophilic contributions to hydration for the side chain shows that both of these aspects of hydration are context-sensitive. Furthermore, analyzing the solute-solvent interaction contribution to the conditional excess enthalpy of the side chain shows that what is nominally considered a property of the side chain includes entirely nonobvious contributions of the background. The context-sensitivity of hydrophobic and hydrophilic hydration and the conflation of background contributions with energetics attributed to the side chain limit the ability of a single scaling factor, such as the fractional solvent exposure of the group in the protein, to map the component energetic contributions of the model-compound data to their value in the protein. But ignoring the origin of cancellations in the underlying components the group-transfer model may appear to provide a reasonable estimate of the free energy for a given error tolerance.
Zimmermann, Eva; Seifert, Udo
2015-02-01
Many single-molecule experiments for molecular motors comprise not only the motor but also large probe particles coupled to it. The theoretical analysis of these assays, however, often takes into account only the degrees of freedom representing the motor. We present a coarse-graining method that maps a model comprising two coupled degrees of freedom which represent motor and probe particle to such an effective one-particle model by eliminating the dynamics of the probe particle in a thermodynamically and dynamically consistent way. The coarse-grained rates obey a local detailed balance condition and reproduce the net currents. Moreover, the average entropy production as well as the thermodynamic efficiency is invariant under this coarse-graining procedure. Our analysis reveals that only by assuming unrealistically fast probe particles, the coarse-grained transition rates coincide with the transition rates of the traditionally used one-particle motor models. Additionally, we find that for multicyclic motors the stall force can depend on the probe size. We apply this coarse-graining method to specific case studies of the F(1)-ATPase and the kinesin motor.
Revisiting the thermodynamic modelling of type I gas-hydroquinone clathrates.
Conde, M M; Torré, J P; Miqueu, C
2016-04-21
Under specific pressure and temperature conditions, certain gaseous species can be engaged in a host lattice of hydroquinone molecules, forming a supramolecular entity called a gas hydroquinone clathrate. This study is devoted to the thermodynamic modelling of type I hydroquinone clathrates. The gases considered in this work are argon, krypton, xenon, methane, nitrogen, oxygen and hydrogen sulphide. The basic van der Waals and Platteeuw model, which is, for example, not able to predict well the phase equilibrium properties of such clathrates at high temperature, is modified and extended by considering first the solubility of the guest in solid HQ and then the mutual interactions between the gaseous molecules inside the clathrate structure (i.e. guest-guest interactions). Other improvements of the basic theory, such as the choice of the reference state, are proposed, and a unique set of thermodynamic parameters valid for all the studied guests are finally calculated. Very good agreement is obtained between the model predictions and the experimental data available in the literature. Our results clearly demonstrate that the highest level of theory is necessary to describe well both the triphasic equilibrium line (where the HQ clathrate, the native hydroquinone HQα and the gas coexist), the occupancy of the guest in the clathrate, and the intercalation enthalpy.
Response of an ocean general circulation model to wind and thermodynamic forcings
Indian Academy of Sciences (India)
A Chakraborty; H C Upadhyaya; O P Sharma
2000-09-01
The stretched-coordinate ocean general circulation model has been designed to study the observed variability due to wind and thermodynamic forcings. The model domain extends from 60°N to 60°S and cyclically continuous in the longitudinal direction. The horizontal resolution is 5° × 5° and 9 discrete vertical levels. First a spin-up experiment has been done with ECMWF-AMIP 1979 January mean fields. The wind stress, ambient atmospheric temperature, evaporation and precipitation have been used in order to derive mechanical and thermodynamical surface forcings. Next, the experiment has been extended for another 30 years (3 cycles each of 10 year period) with varying surface boundary conditions (from January 1979 to December 1988 of ECMWF-AMIP monthly fields for each cycle) along with 120 years extended spin-up control run's results as initial conditions. The results presented here are for the last 10 years simulations. The preliminary results of this experiment show that the model is capable of simulating some of the general features and the pattern of interannual variability of the ocean.
Thermodynamic constitutive model for load-biased thermal cycling test of shape memory alloy
Energy Technology Data Exchange (ETDEWEB)
Young, Sung, E-mail: ysy@kut.ac.kr [Korea University of Technology and Education, Chonan (Korea, Republic of); Nam, Tae-Hyun, E-mail: tahynam@gnu.ac.kr [School of Materials Science and Engineering and ERI, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of)
2013-12-15
Graphical abstract: - Highlights: • Thermodynamic calculation model for martensitic transformation of shape memory alloy was proposed. • Evolution of the self-accommodation was considered independently by a rate-dependent kinetic equation. • Finite element calculation was conducted for B2–B19′ transformation of Ti–44.5Ni–5Cu–0.5 V (at.%). • Three-dimensional numerical results predict the macroscopic strain under bias loading accurately. - Abstract: This paper presents a three-dimensional calculation model for martensitic phase transformation of shape memory alloy. Constitutive model based on thermodynamic theory was provided. The average behavior was accounted for by considering the volume fraction of each martensitic variant in the material. Evolution of the volume fraction of each variant was determined by a rate-dependent kinetic equation. We assumed that nucleation rate is faster for the self-accommodation than for the stress-induced variants. Three-dimensional finite element analysis was conducted and the results were compared with the experimental data of Ti–44.5Ni–5Cu–0.5 V (at.%) alloy under bias loading.
Latent Heating Retrieval from TRMM Observations Using a Simplified Thermodynamic Model
Grecu, Mircea; Olson, William S.
2003-01-01
A procedure for the retrieval of hydrometeor latent heating from TRMM active and passive observations is presented. The procedure is based on current methods for estimating multiple-species hydrometeor profiles from TRMM observations. The species include: cloud water, cloud ice, rain, and graupel (or snow). A three-dimensional wind field is prescribed based on the retrieved hydrometeor profiles, and, assuming a steady-state, the sources and sinks in the hydrometeor conservation equations are determined. Then, the momentum and thermodynamic equations, in which the heating and cooling are derived from the hydrometeor sources and sinks, are integrated one step forward in time. The hydrometeor sources and sinks are reevaluated based on the new wind field, and the momentum and thermodynamic equations are integrated one more step. The reevalution-integration process is repeated until a steady state is reached. The procedure is tested using cloud model simulations. Cloud-model derived fields are used to synthesize TRMM observations, from which hydrometeor profiles are derived. The procedure is applied to the retrieved hydrometeor profiles, and the latent heating estimates are compared to the actual latent heating produced by the cloud model. Examples of procedure's applications to real TRMM data are also provided.
Thermodynamic model for glass forming ability of ternary metallic glass systems
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The thermodynamic model of multicomponent chemical short range order (MCSRO) was established in order to evaluate the glass forming ability (GFA) of ternary alloys. Comprehensive numerical calculations using MSCRO software were conducted to obtain the composition dependence of the MCSRO undercooling in Zr-Ni-Cu, Zr-Si-Cu and Pd-Si-Cu ternary systems. By the MCSRO undercooling principle, the composition range of Zr-Ni-Cu system with optimum GFA is determined to be 62.5～75Zr, 5～20Cu, 12.5～25Ni (n(Ni)/n(Cu)=1～5). The TTT curves of Zr-Ni-Cu system were also calculated based on the MCSRO model. The critical cooling rates for Zr-based alloy with deep MSCRO undercooling are estimated to be as low as 100?K/s, which is consistent with the practical cooling rate in the preparation of Zr-based bulk metallic glass (BMG). The calculation also illustrates that the easy glass forming systems such as Pd-based alloys exhibit an extraordinary deep MCSRO undercooling. It is shown that the thermodynamic model of MCSRO provides an effective method for the alloy designing of BMG.
Thermodynamics and higher order moments in SU(3) linear σ-model with gluonic quasiparticles
Nasser Tawfik, Abdel; Magdy, Niseem
2015-01-01
In the framework of the linear σ-model (LSM) with three quark flavors, the chiral phase diagram at finite temperature and density is investigated. For temperatures higher than the critical temperature ({{T}c}), we added to the LSM the gluonic sector from the quasi-particle model (QPM), which assumes that the interacting gluons in the strongly interacting matter, the quark-gluon plasma (QGP), are phenomenologically the same as non-interacting massive quasi-particles. The dependence of the chiral condensates of strange and non-strange quarks on the temperature and chemical potential is analyzed. Then, we calculate the thermodynamics in the new approach (using a combination of the LSM and the QPM). Confronting the results with those from recent lattice quantum chromodynamics simulations reveals an excellent agreement for almost all thermodynamic quantities. The dependences of the first-order and second-order moments of the particle multiplicity on the chemical potential at fixed temperature are studied. These investigations are implemented through characterizing the large fluctuations accompanying the chiral phase transition. The results for the first-order and second-order moments are compared with those from the SU(3) Polyakov linear σ-model (PLSM). Also, the resulting phase diagrams deduced in the PLSM and the LSM+QPM are compared with each other.
Thermodynamic modelling of phase equilibria in Al–Ga–P–As system
Indian Academy of Sciences (India)
S Acharya; J P Hajra
2005-04-01
A generalized thermodynamic expression of the liquid Al–Ga–P–As alloys is used in conjunction with the solid solution model in determining the solid–liquid equilibria at 1173 K and 1273 K. The liquid solution model contains thirtyseven parameters. Twentyfour of them pertain to those of the six constituent binaries, twelve refer to the specific ternary interactions. Additionally the liquid solution model also contains a specific quaternary interaction parameter. The latter has been evaluated here based on the experimental data available in the literature. The present research shows an excellent agreement between the derived and experimental values at 1173 K and 1273 K for the system. The article also presents a comparison between the evaluated values with those based on the regular solution model for the liquid alloys.
A Combined Thermodynamic and Kinetic Model for Barite Prediction at Oil Reservoir Conditions
DEFF Research Database (Denmark)
Zhen Wu, Bi Yun
of the literature (PhD Study 1). The reviewed dataset was used as starting point for geochemical speciation modelling and applied to predict the stability of sulphate minerals in North Sea oil field brines. Second, for modelling of high salinity solutions using the Pitzer ion interaction approach, the temperature......In marine environments, barite (BaSO4) is a key proxy that has been used for understanding the biological and chemical evolution of oceans and for tracking the origin of fluids. In the oil industry, barite scale can clog pipelines and pores in the reservoirs, reducing oil yield. The goal...... of this research was to develop a model, based on thermodynamics and kinetics, for predicting barite precipitation rates in saline waters at the pressures and temperatures of oil bearing reservoirs, using the geochemical modelling code PHREEQC. This task is complicated by the conditions where traditional methods...
Towards a functional model of mental disorders incorporating the laws of thermodynamics.
Murray, George C; McKenzie, Karen
2013-05-01
The current paper presents the hypothesis that the understanding of mental disorders can be advanced by incorporating the laws of thermodynamics, specifically relating to energy conservation and energy transfer. These ideas, along with the introduction of the notion that entropic activities are symptomatic of inefficient energy transfer or disorder, were used to propose a model of understanding mental ill health as resulting from the interaction of entropy, capacity and work (environmental demands). The model was applied to Attention Deficit Hyperactivity Disorder, and was shown to be compatible with current thinking about this condition, as well as emerging models of mental disorders as complex networks. A key implication of the proposed model is that it argues that all mental disorders require a systemic functional approach, with the advantage that it offers a number of routes into the assessment, formulation and treatment for mental health problems.
A Molecular Thermodynamic Model for Restricted Swelling Behaviors of Thermo-sensitive Hydrogel☆
Institute of Scientific and Technical Information of China (English)
Cheng Lian; Dongyan Zhi; Shouhong Xu; Honglai Liu
2014-01-01
A molecular thermodynamic model was developed for describing the restricted swelling behavior of a thermo-sensitive hydrogel confined in a limited space. The Gibbs free energy includes two contributions, the contribution of mixing of polymer and solvent calculated by using the lattice model of random polymer solution, and the con-tribution due to the elasticity of polymer network. This model can accurately describe the swel ing behavior of restricted hydrogels under uniaxial and biaxial constraints by using two model parameters. One is the interaction energy parameter between polymer network and solvent, and the other is the size parameter depending on the degree of cross-linking. The calculated results show that the swelling ratio reduces significantly and the phase transition temperature decreases slightly as the restricted degree increases, which agree wel with the experi-mental data.
Lanzetta, F; Baucour, P
2016-01-01
Different economical configurations, due for instance to the relative cost of the fuel it consumes, can push a heat engine into operating whether at maximum efficiency or at maximum power produced. Any relevant design of such system hence needs to be based, at least partly, on the knowledge of its specific "power vs. efficiency" characteristic curve. However, even when a simple model is used to describe the engine, obtained for example thanks to Finite Dimensions Thermodynamics, such characteristic curve is often difficult to obtain and takes an explicit form only for the simplest of these models. When more realistic models are considered, including complex internal subsystems or processes, an explicit expression for this curve is practically impossible to obtain. In this paper, we propose to use the called Graham's scan algorithm in order to directly obtain the power vs. efficiency curve of a realistic Stirling engine model, which includes heat leakage, regenerator effectiveness, as well as internal and exte...
Quality by design--thermodynamic modelling of chromatographic separation of proteins.
Mollerup, Jørgen M; Hansen, Thomas Budde; Kidal, Steffen; Staby, Arne
2008-01-11
A desired goal of the PAT framework is to design and develop well-understood processes that will consistently ensure a predefined quality at the end of the manufacturing process. Such procedures would be consistent with the basic tenet of quality by design and could reduce risks to quality and regulatory concerns while improving efficiency. To support a more in-depth understanding of the design and development of a chromatographic purification process the paper discusses the general thermodynamic principles of ligand-binding and models of multi-component adsorption in ion-exchange and hydrophobic chromatography. The parameters in the models are easy to determine and have a well-defined physical significance. Examples demonstrate how the model parameters can be determined from experimental data and in order to validate the model, simulated chromatograms are compared to the corresponding experimental chromatograms. Finally it is demonstrated how a simulation can be used to explain an aberration.
Zuend, A.; Marcolli, C.; Luo, B.; Peter, T.
2008-12-01
Tropospheric aerosol particles contain mixtures of inorganic salts, acids, water, and a large variety of organic compounds. Interactions between these substances in liquid mixtures lead to discrepancies from ideal thermodynamic behavior. While the thermodynamics of aqueous inorganic systems at atmospheric temperatures are well established, little is known about the physicochemistry of mixed organic-inorganic particles. Salting-out and salting-in effects result from organic-inorganic interactions and are used to improve industrial separation processes. In the atmosphere, they may influence the aerosol phases. Liquid-liquid phase separations into a mainly polar (aqueous) and a less polar organic phase may considerably influence the gas/particle partitioning of semi-volatile substances compared to a single phase estimation. Moreover, the phases present in the aerosol define the reaction medium for heterogeneous and multiphase chemistry occurring in aerosol particles. A correct description of these phases is needed when gas- or cloud-phase reaction schemes are adapted to aerosols. Non-ideal thermodynamic behavior in mixtures is usually described by an expression for the excess Gibbs energy. We present the group-contribution model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients), which explicitly accounts for molecular interactions between solution constituents, both organic and inorganic, to calculate activities, chemical potentials and the total Gibbs energy of mixed systems. This model allows to compute vapor-liquid (VLE), liquid-liquid (LLE) and solid-liquid (SLE) equilibria within one framework. Focusing on atmospheric applications we considered eight different cations, five anions and a wide range of alcohols/polyols as organic compounds. With AIOMFAC, the activities of the components within an aqueous electrolyte solution are very well represented up to high ionic strength. We show that the semiempirical middle
Nakano, Tadashi; Moore, Michael
2017-01-01
(Preliminary) The book presents the state of art in the emerging field of molecular and nanoscale communication. It gives special attention to fundamental models, and advanced methodologies and tools used in the field. It covers a wide range of applications, e.g. nanomedicine, nanorobot communication, bioremediation and environmental managements. It addresses advanced graduate students, academics and professionals working at the forefront in their fields and at the interfaces between different areas of research, such as engineering, computer science, biology and nanotechnology.
Ito, Sosuke
2016-11-01
The transfer entropy is a well-established measure of information flow, which quantifies directed influence between two stochastic time series and has been shown to be useful in a variety fields of science. Here we introduce the transfer entropy of the backward time series called the backward transfer entropy, and show that the backward transfer entropy quantifies how far it is from dynamics to a hidden Markov model. Furthermore, we discuss physical interpretations of the backward transfer entropy in completely different settings of thermodynamics for information processing and the gambling with side information. In both settings of thermodynamics and the gambling, the backward transfer entropy characterizes a possible loss of some benefit, where the conventional transfer entropy characterizes a possible benefit. Our result implies the deep connection between thermodynamics and the gambling in the presence of information flow, and that the backward transfer entropy would be useful as a novel measure of information flow in nonequilibrium thermodynamics, biochemical sciences, economics and statistics.
REE Zonation in Garnet: new insights from combined Thermodynamic and Diffusion Modelling
Witte, C.; Konrad-Schmolke, M.
2013-12-01
Compositional variation in garnet provides an excellent record of element transport within their host rocks, as it precisely reflects the interplay between thermodynamically-controlled nutrient demand and kinetically-constrained element availability during growth. Element availability is controlled by (1) the thermodynamically controlled element distribution among co-existing phases and (2) by matrix transport properties. Our task is to distinguish between factors controlling the availability of major- and trace-elements and to quantify their diffusion length scales but this is hindered by the fact that the interplay of different rate-limiting factors on garnet growth and composition are not fully understood. These processes comprise: (1) fractional garnet crystallisation, which continuously changes the effective, i.e. reacting, bulk rock chemistry (EBC), which in turn influences garnet proportion, growth rate and composition; (2) kinetically-controlled element availability, such that grain boundary diffusion in the host rock's interconnecting transport matrix (ITM) or surface processes in reacting phases cannot keep pace with the material required for garnet nucleation and growth in homogeneous thermodynamic equilibrium with the coexisting phase assemblage and (3) reaction-controlled trace element availability in the host rock, which is often reflected in discontinuous trace element zoning patterns in garnet. A 1D diffusion and reaction model was developed to investigate REE distribution patterns in garnet. It combines PERPLEX thermodynamic forward modelling for a bulk rock composition along a P-T-path with control of diffusion rates in the matrix fluid which acts as a transport medium in the intergranular space. Initial REE distribution is controlled by standard distribution coefficients. Reactant phases are the source of REE and product minerals fractionate REE from the transport medium. Thus the uptake of REE in garnet is regulated by: (1) thermodynamically
Svendsen, B.; Hutter, K.; Laloui, L.
This work deals with the thermodynamic formulation of constitutive models for materials whose quasi-static behaviour is governed by internal friction, e.g., dry granular materials. The process of internal friction is represented here phenomenologically with the help of a second-order, symmetric-tensor-valued internal variable. A general class of models for the evolution of this variable is considered, including as special cases a hypoelastic-like form for this relation as well as the hypoplastic form of Kolymbas (1991). The thermodynamic formulation is carried out in the context of the Müller-Liu entropy principle. Among other things, it is shown that for the hypoelastic-type models, a true equilibrium inelastic Cauchy stress exists. On the other hand, such a stress does not exist for the hypoplastic model due to its rate-independence and incremental non-linearity. With the help of a slight generalization of the notion of thermodynamic equilibrium, i.e., to thermodynamic ``quasi-equilibrium,'' however, such a Cauchy stress can be formulated for the hypoplastic model. As it turns out, this quasi-equilibrium for the Cauchy stress represents a thermodynamic generalization of the so-called quasi-static stress postulated for example by Goddard (1986) in the context of his viscoplastic model for a frictional-dissipative, and in particular for granular, materials.
Vinyard, David J; Zachary, Chase E; Ananyev, Gennady; Dismukes, G Charles
2013-07-01
Forty-three years ago, Kok and coworkers introduced a phenomenological model describing period-four oscillations in O2 flash yields during photosynthetic water oxidation (WOC), which had been first reported by Joliot and coworkers. The original two-parameter Kok model was subsequently extended in its level of complexity to better simulate diverse data sets, including intact cells and isolated PSII-WOCs, but at the expense of introducing physically unrealistic assumptions necessary to enable numerical solutions. To date, analytical solutions have been found only for symmetric Kok models (inefficiencies are equally probable for all intermediates, called "S-states"). However, it is widely accepted that S-state reaction steps are not identical and some are not reversible (by thermodynamic restraints) thereby causing asymmetric cycles. We have developed a mathematically more rigorous foundation that eliminates unphysical assumptions known to be in conflict with experiments and adopts a new experimental constraint on solutions. This new algorithm termed STEAMM for S-state Transition Eigenvalues of Asymmetric Markov Models enables solutions to models having fewer adjustable parameters and uses automated fitting to experimental data sets, yielding higher accuracy and precision than the classic Kok or extended Kok models. This new tool provides a general mathematical framework for analyzing damped oscillations arising from any cycle period using any appropriate Markov model, regardless of symmetry. We illustrate applications of STEAMM that better describe the intrinsic inefficiencies for photon-to-charge conversion within PSII-WOCs that are responsible for damped period-four and period-two oscillations of flash O2 yields across diverse species, while using simpler Markov models free from unrealistic assumptions. Copyright © 2013 Elsevier B.V. All rights reserved.
Jacobs, M.H.G.; van den Berg, A.P.; Schmid-Fetzer, R.
2013-01-01
We use Kieffer's model to represent the vibrational density of states (VDoS) and thermodynamic properties of pure substances in pressure-temperature space. We show that this model can be simplified to a vibrational model in which the VDoS is represented by multiple Einstein frequencies without
Thermodynamic Modelling of Fe-Cr-Ni-Spinel Formation at the Light-Water Reactor Conditions
Energy Technology Data Exchange (ETDEWEB)
Kurepin, V.A.; Kulik, D.A.; Hitpold, A.; Nicolet, M
2002-03-01
In the light water reactors (LWR), the neutron activation and transport of corrosion products is of concern in the context of minimizing the radiation doses received by the personnel during maintenance works. A practically useful model for transport and deposition of the stainless steel corrosion products in LWR can only be based on an improved understanding of chemical processes, in particular, on the attainment of equilibrium in this hydrothermal system, which can be described by means of a thermodynamic solid-solution -aqueous-solution (SSAS) model. In this contribution, a new thermodynamic model for a Fe-Cr-Ni multi-component spinel solid solutions was developed that considers thermodynamic consequences of cation interactions in both spinel sub-Iattices. The obtained standard thermodynamic properties of two ferrite and two chromite end-members and their mixing parameters at 90 bar pressure and 290 *c temperature predict a large miscibility gap between (Fe,Ni) chromite and (Fe,Ni) ferrite phases. Together with the SUPCRT92-98 thermo- dynamic database for aqueous species, the 'spinel' thermodynamic dataset was applied to modeling oxidation of austenitic stainless steel in hydrothermal water at 290*C and 90 bar using the Gibbs energy minimization (GEM) algorithm, implemented in the GEMS-PSI code. Firstly, the equilibrium compositions of steel oxidation products were modelIed as function of oxygen fugacity .fO{sub 2} by incremental additions of O{sub 2} in H{sub 2}O-free system Cr-Fe- Ni-O. Secondly, oxidation of corrosion products in the Fe-Cr-Ni-O-H aquatic system was modelIed at different initial solid/water ratios. It is demonstrated that in the transition region from hydrogen regime to oxygen regime, the most significant changes in composition of two spinel-oxide phases (chromite and ferrite) and hematite must take place. Under more reduced conditions, the Fe-rich ferrite (magnetite) and Ni-poor chromite phases co-exist at equilibrium with a metal Ni
Experimental determination and thermodynamic modeling of the Ni-Re binary system
Energy Technology Data Exchange (ETDEWEB)
Yaqoob, Khurram [Chimie Metallurgique des Terres Rares (CMTR), Institut de Chimie et des Materiaux Paris-Est (ICMPE), 2-8 rue Henri Dunant, 94320 Thiais Cedex (France); Joubert, Jean-Marc, E-mail: jean-marc.joubert@icmpe.cnrs.fr [Chimie Metallurgique des Terres Rares (CMTR), Institut de Chimie et des Materiaux Paris-Est (ICMPE), 2-8 rue Henri Dunant, 94320 Thiais Cedex (France)
2012-12-15
The phase diagram of the Ni-Re binary system has been partially reinvestigated by chemical, structural and thermal characterization of the arc melted alloys. The experimental results obtained during the present investigation were combined with the literature data and a new phase diagram of the Ni-Re binary system is proposed. In comparison with the Ni-Re phase diagram proposed by Nash et al. in 1985 [1], significant differences in the homogeneity domains, freezing ranges and peritectic reaction temperature were evidenced. On the other hand, thermodynamic modeling of the studied system by using the new experimental information has also been carried out with the help of the CALPHAD method. The calculated Ni-Re phase diagram showed a good agreement with the selected experimental information. - Graphical abstract: Ni-Re phase diagram according to the present study. Highlights: Black-Right-Pointing-Pointer Re-investigation of the Ni-Re phase diagram. Black-Right-Pointing-Pointer Extended phase field of the hcp phase. Black-Right-Pointing-Pointer Different freezing ranges and peritectic reaction temperature. Black-Right-Pointing-Pointer Thermodynamic modeling of the studied system by using the CALPHAD method.
Thermal stability of pepsin: A predictive thermodynamic model of a multi-domain protein
Directory of Open Access Journals (Sweden)
Ali Asghar Rastegari
2017-03-01
Full Text Available Pepsin is generally used in the preparation of F(ab2 fragments from antibodies. The antibodies that are one of the largest and fastest growing categories of bio- pharmaceutical candidates. Differential scanning calorimetric is principally suitable method to follow the energetics of a multi-domain, fragment to perform a more exhaustive description of the thermodynamics in an associating system. The thermodynamical models of analysis include the construction of a simultaneous fitting of a theoretical expression. The expression depending on the equilibrium unfolding data from multimeric proteins that have a two-state monomer. The aim of the present study is considering the DSC data in connection with pepsin going through reversible thermal denaturation. Afterwards, we calculate the homology modeling identification of pepsin in complex multi-domain families with varied domain architectures. In order to analyze the DSC data, the thermal denaturation of multimer proteins were considered, the “two independent two-state sequential transitions with domains dissociation model” was introduced by using of the effective ΔG concept. The reversible unfolding of the protein description was followed by the two-state transition quantities which is a slower irreversible process of aggregation. The protein unfolding is best described by two non-ideal transitions, suggesting the presence of unfolding intermediates. These evaluations are also applicable for high throughput investigation of protein stability.
Energy Technology Data Exchange (ETDEWEB)
Yoozbashi, M.N., E-mail: N_Yoozbashi@sut.ac.ir [Faculty of Materials Engineering, Sahand University of Technology, Tabriz (Iran, Islamic Republic of); Yazdani, S., E-mail: Yazdani@sut.ac.ir [Faculty of Materials Engineering, Sahand University of Technology, Tabriz (Iran, Islamic Republic of)
2010-05-25
Nanostructured, low temperature bainitic steels with remarkable combination of ultimate tensile strength of about 2.5 GPa and high uniform elongation have been developed in the recent decade. To reduce the production cost of these steels, two chemical compositions were designed by using a thermodynamic model which was developed in Cambridge University by Bhadeshia. To attain optimum mechanical properties, the designed steels were transformed isothermally at the temperature range of 200-300 deg. C for different times. The optimum times for each temperature were estimated by evaluation of hardness and XRD results. The measurements of tensile properties and the fracture surface examination by scanning electron microscopy indicated that by modification of chemical composition the cost production of steel not only reduces, but also the mechanical properties particularly total elongation enhances slightly. The results of this study suggest that by using a thermodynamic model and without try and error it is possible to design a new steel with remarkable combination of mechanical properties.
Institute of Scientific and Technical Information of China (English)
沈志刚; 李世刚; 刘朝文; 张建文; 陈建峰
2005-01-01
A thermodynamic model has been developed to determine the reaction conditions favoring low temperature direct synthesis of barium titanate (BaTiO3). The method utilizes standard-state thermodynamic data for solid and aqueous species and a Debye-Hǔckel coefficients model to represent solution nonideality. The method has been used to generate phase stability diagrams that indicate the ranges of pH and reagent concentrations, for which various species predominate in the system at a given temperature. Also, yield diagrams have been constructed that indicate the concentration, pH and temperature conditions for which different yields of crystalline BaTiO3 can be obtained. The stability and yield diagrams have been used to predict the optimum synthesis conditions (e.g.,reagent concentrations, pH and temperature). Subsequently, these predictions have been experimentally verified.As a result, phase-pure perovskite BaTiO3 has been obtained at temperature ranging from 55 to 85℃ using BaCl2,TiCl4 as a source for Ba and Ti. and NaOH as a orecioitator.
A thermodynamic approach to model the caloric properties of semicrystalline polymers
Lion, Alexander; Johlitz, Michael
2016-05-01
It is well known that the crystallisation and melting behaviour of semicrystalline polymers depends in a pronounced manner on the temperature history. If the polymer is in the liquid state above the melting point, and the temperature is reduced to a level below the glass transition, the final degree of crystallinity, the amount of the rigid amorphous phase and the configurational state of the mobile amorphous phase strongly depend on the cooling rate. If the temperature is increased afterwards, the extents of cold crystallisation and melting are functions of the heating rate. Since crystalline and amorphous phases exhibit different densities, the specific volume depends also on the temperature history. In this article, a thermodynamically based phenomenological approach is developed which allows for the constitutive representation of these phenomena in the time domain. The degree of crystallinity and the configuration of the amorphous phase are represented by two internal state variables whose evolution equations are formulated under consideration of the second law of thermodynamics. The model for the specific Gibbs free energy takes the chemical potentials of the different phases and the mixture entropy into account. For simplification, it is assumed that the amount of the rigid amorphous phase is proportional to the degree of crystallinity. An essential outcome of the model is an equation in closed form for the equilibrium degree of crystallinity in dependence on pressure and temperature. Numerical simulations demonstrate that the process dependences of crystallisation and melting under consideration of the glass transition are represented.
A Combined Thermodynamic and Kinetic Model for Barite Prediction at Oil Reservoir Conditions
DEFF Research Database (Denmark)
Zhen Wu, Bi Yun
of this research was to develop a model, based on thermodynamics and kinetics, for predicting barite precipitation rates in saline waters at the pressures and temperatures of oil bearing reservoirs, using the geochemical modelling code PHREEQC. This task is complicated by the conditions where traditional methods....... Calculations for a well with seawater breakthrough results in an overestimation compared to scale samples, suggesting that significant amounts of barite precipitate in the reservoirs prior to entering to the wells. The combined model allows estimates of barite scaling rates that can be compared with field......In marine environments, barite (BaSO4) is a key proxy that has been used for understanding the biological and chemical evolution of oceans and for tracking the origin of fluids. In the oil industry, barite scale can clog pipelines and pores in the reservoirs, reducing oil yield. The goal...
DEFF Research Database (Denmark)
Nguyen, Tuong-Van; Elmegaard, Brian
2016-01-01
Natural gas liquefaction systems are based on refrigeration cycles – they consist of the same operations such as heat exchange, compression and expansion, but they have different layouts, components and working fluids. The design of these systems requires a preliminary simulation and evaluation...... of their performance. However, the thermodynamic models used for this purpose are characterised by different mathematical formulations, ranges of application and levels of accuracy. This may lead to inconsistent results when estimating hydrocarbon properties and assessing the efficiency of a given process. This paper...... presents a thorough comparison of six equations of state widely used in the academia and industry, including the GERG-2008 model, which has recently been adopted as an ISO standard for natural gases. These models are used to (i) estimate the thermophysical properties of a Danish natural gas, (ii) simulate...
Naumis, Gerardo G
2012-06-01
When a liquid melt is cooled, a glass or phase transition can be obtained depending on the cooling rate. Yet, this behavior has not been clearly captured in energy-landscape models. Here, a model is provided in which two key ingredients are considered in the landscape, metastable states and their multiplicity. Metastable states are considered as in two level system models. However, their multiplicity and topology allows a phase transition in the thermodynamic limit for slow cooling, while a transition to the glass is obtained for fast cooling. By solving the corresponding master equation, the minimal speed of cooling required to produce the glass is obtained as a function of the distribution of metastable states.
A statistic-thermodynamic model for the DOM degradation in the estuary
Zheng, Quanan; Chen, Qin; Zhao, Haihong; Shi, Jiuxin; Cao, Yong; Wang, Dan
2008-03-01
This study aims to clarify the role of dissolved salts playing in the degradation process of terrestrial dissolved organic matter (DOM) at a scale of molecular movement. The molecular thermal movement is perpetual motion. In a multi-molecular system, this random motion also causes collision between the molecules. Seawater is a multi-molecular system consisting from water, salt, and terrestrial DOM molecules. This study attributes the DOM degradation in the estuary to the inelastic collision of DOM molecule with charged salt ions. From statistic-thermodynamic theories of molecular collision, the DOM degradation model and the DOM distribution model are derived. The models are validated by the field observations and satellite data. Thus, we conclude that the inelastic collision between the terrestrial DOM molecules and dissolved salt ions in seawater is a decisive dynamic mechanism for rapid loss of terrestrial DOM.
Thermodynamics and classification of cosmological models in the Horava-Lifshitz theory of gravity
Energy Technology Data Exchange (ETDEWEB)
Wang, Anzhong; Wu, Yumei, E-mail: anzhong_wang@baylor.edu, E-mail: yumei_wu@baylor.edu [GCAP-CASPER, Physics Department, Baylor University, Waco, TX 76798-7316 (United States)
2009-07-01
We study thermodynamics of cosmological models in the Horava-Lifshitz theory of gravity, and systematically investigate the evolution of the universe filled with a perfect fluid that has the equation of state p = wρ, where p and ρ denote, respectively, the pressure and energy density of the fluid, and w is an arbitrary real constant. Depending on specific values of the free parameters involved in the models, we classify all of them into various cases. In each case the main properties of the evolution are studied in detail, including the periods of deceleration and/or acceleration, and the existence of big bang, big crunch, and big rip singularities. We pay particular attention on models that may give rise to a bouncing universe.
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
Radiative fluxes are of primary importance in the energy and mass balance of the sea-ice cover. Various parameterizations of the radiative fluxes are studied in a thermodynamic sea-ice model. Model outputs of the surface radiative and heat fluxes and mass balance are compared with observations. The contribution of short-wave radiation is limited to a long part of winter. Therefore, simple schemes are often sufficient. Errors in estimations of the short-wave radiation are due mainly to cloud effects and occasionally to multi-reflection between surface and ice crystals in the air. The long-wave radiation plays an important role in the ice surface heat and mass balance during most part of a winter. The effect of clouds on the accuracy of the simple radiative schemes is critical, which needs further attention. In general, the accuracy of an ice model depends on that of the radiative fluxes.
The Ti-Mn system revisited: experimental investigation and thermodynamic modelling.
Khan, A U; Brož, P; Premović, M; Pavlů, J; Vřeštál, J; Yan, X; Maccio, D; Saccone, A; Giester, G; Rogl, P
2016-08-17
As the Ti-Mn phase diagram is part of numerous ternary and higher order systems of technological importance, the present paper defines phase relations which have been experimentally established throughout this work from 800 °C to the melting range based on Differential Thermal Analyses (DTA), X-ray powder diffraction, metallography and Electron Probe Micro Analysis (EPMA) techniques on ∼50 alloys, which were prepared by arc melting or high frequency melting under high purity argon starting from freshly cleaned metal ingots. Novel compounds were identified and reaction isotherms were redefined accordingly. In the Ti-rich region a novel compound TiMn was detected, sandwiched between the known phases: TiMn1-x (∼45 at% Mn) and TiMn1+x (∼55 at% Mn). In the Mn-rich region the hitherto unknown crystal structure of TiMn∼3 was solved from X-ray single crystal diffraction data and found to be of a unique structure type Ti6(Ti1-xMnx)6Mn25 (x = 0.462; space group Pbam (#55); a = 0.79081(3) nm, b = 2.58557(9) nm, c = 0.47931(2) nm), which consists of two consecutive layers of the hexagonal MgZn2-type Laves phase (TiMn2) and a combined layer of alternate structure blocks of MgZn2 type and Zr4Al3 type. Whereas TiMn can be considered as a line compound (solubility range phase: Ti8(TixMn1-x)6Mn39, 80 to 84 at% Ti). Supported by ab initio calculations of the ground state energy for the Laves phase, the new experimental results enabled thermodynamic modelling of the entire Ti-Mn phase diagram providing a complete and novel set of thermodynamic data thus providing a sound basis for future thermodynamic predictions of higher order Ti-Mn-X-Y systems.
Models of thermodynamic and transport properties of POE VG68 and R410A/POE VG68 mixture
Institute of Scientific and Technical Information of China (English)
2008-01-01
The thermodynamic properties of a refrigerantoil mixture are the foundation to predict the performance of air-conditioning and refrigeration systems and to evaluate the influence of oil on heat transfer and pressure drop.Models of the thermodynamic and transport properties of POE VG68 and R410A/POE VG68 mixture were provided based on the analysis of state-of-the-art correlations.New models were developed by modifying the coefficients in existing correlations with multiple regression method according to experimental data.The maximum deviation of the predicted values of these models to the experimental data is within 5%.These models can be used for R410A/POE VG68 to obtain accurate and reliable thermodynamic and transport parameters to evaluate the influence of POE VG68 on the performance of an R410A air-conditioning and refrigeration system.
Ghiorso, M. S.
2012-12-01
The computer program PhasePlot was developed for Macintosh computers and released via the Mac App Store in December 2011. It permits the visualization of phase relations calculated from internally consistent thermodynamic data-model collections, including those from MELTS (Ghiorso and Sack, 1995, CMP 119, 197-212), pMELTS (Ghiorso et al., 2002, G-cubed 3, 10.1029/2001GC000217) and the deep mantle database of Stixrude and Lithgow-Bertelloni (2011, GJI 184, 1180-1213). The software allows users to enter a system bulk composition and a range of reference conditions, and then calculate a grid of phase relations. These relations may be visualized in a variety of ways including pseudosections, phase diagrams, phase proportion plots, and contour diagrams of phase compositions and abundances. The program interface is user friendly and the computations are fast on laptop-scale machines, which makes PhasePlot amenable to in-class demonstrations, as a tool in instructional laboratories, and as an aid in support of out-of-class exercises and research. Users focus on problem specification and interpretation of results rather than on manipulation and mechanics of computation. The software has been developed with NSF support and is free. The PhasePlot web site is at phaseplot.org where extensive user documentation, video tutorials and examples of use may be found. The original release of phase plot permitted calculations to be performed on pressure-, temperature-grids (P-T), by direct minimization of the Gibbs free energy of the system at each grid point. A revision of PhasePlot (scheduled for release to the Mac App Store in December 2012) extends capabilities to include pressure-, entropy-grids (P-S) by system enthalpy minimization, volume-, temperature-grids (V-T) by system Helmholtz energy minimization, and volume-,entropy-grids (V-S) by minimization of the Internal Energy of the system. P-S gridded results may be utilized to visualize phase relations as a function of heat
Energy Technology Data Exchange (ETDEWEB)
Mesmer, R.E.
1990-09-12
The purpose of this travel was for the traveler to participate in the 11th IUPAC International Conference on Chemical Thermodynamics and to present a paper of which he is co-author entitled The Transition from Strong-to-Weak Electrolyte Behavior Near the Critical Point of Water'' in the session on Solutions. The conference brought together nearly 500 scientists from around the world to discuss broad aspects of experimental thermodynamics and theoretical modeling. The traveler also visited the University of Karlsruhe to discuss current research with E.U. Franck and his collaborators. This institution has been for many years one of the leading centers for experimental studies on phase equilibrium and physical chemical studies especially on pure substances under the direction of Franck.
A multi-scale model for geared transmission aero-thermodynamics
McIntyre, Sean M.
A multi-scale, multi-physics computational tool for the simulation of high-per- formance gearbox aero-thermodynamics was developed and applied to equilibrium and pathological loss-of-lubrication performance simulation. The physical processes at play in these systems include multiphase compressible ow of the air and lubricant within the gearbox, meshing kinematics and tribology, as well as heat transfer by conduction, and free and forced convection. These physics are coupled across their representative space and time scales in the computational framework developed in this dissertation. These scales span eight orders of magnitude, from the thermal response of the full gearbox O(100 m; 10 2 s), through effects at the tooth passage time scale O(10-2 m; 10-4 s), down to tribological effects on the meshing gear teeth O(10-6 m; 10-6 s). Direct numerical simulation of these coupled physics and scales is intractable. Accordingly, a scale-segregated simulation strategy was developed by partitioning and treating the contributing physical mechanisms as sub-problems, each with associated space and time scales, and appropriate coupling mechanisms. These are: (1) the long time scale thermal response of the system, (2) the multiphase (air, droplets, and film) aerodynamic flow and convective heat transfer within the gearbox, (3) the high-frequency, time-periodic thermal effects of gear tooth heating while in mesh and its subsequent cooling through the rest of rotation, (4) meshing effects including tribology and contact mechanics. The overarching goal of this dissertation was to develop software and analysis procedures for gearbox loss-of-lubrication performance. To accommodate these four physical effects and their coupling, each is treated in the CFD code as a sub problem. These physics modules are coupled algorithmically. Specifically, the high- frequency conduction analysis derives its local heat transfer coefficient and near-wall air temperature boundary conditions from a quasi
Energy Technology Data Exchange (ETDEWEB)
C. M. Frazee; J. D. Christian
2004-02-01
To send calcine produced at Idaho National Engineering and Environmental Laboratory to the Yucca Mountain Project for disposal, characterization information will be required. To sample calcine from its existing storage location would require extensive personnel exposure. Sufficient analyses of the chemical composition of the calcine would be extremely difficult and very expensive. In support of characterization development, the chemical composition of calcine from Bin 3 of Calcine Solid Storage Facility II was thermodynamic modeled. This calcine was produced in the Waste Calcination Facility during its second processing campaign, operating with indirect heating at 400 C and 0.744 bar (0.734 atm) during processing of aluminum high-level liquid waste (first cycle extraction raffinate from reprocessing aluminum-clad fuels) from tanks WM-180 and -182 from December 27, 1966 through August 26, 1967. The current modeling effort documents the input compositional data (liquid feed and calciner off-gas) for Batches 300 - 620 and a methodology for estimating the calcine chemical composition. The results, along with assumptions and limitations of the thermodynamic calculations, will serve as a basis for benchmarking subsequent calculations. This will be done by comparing the predictions against extensive analytical results that are currently being obtained on representative samples of the modeled calcine. A commercial free-energy minimization program and database, HSC 5.1, was used to perform the thermodynamic calculations. Currently available experimental data and process information on the calcine were used to make judgments about specific phases and compounds to include and eliminate in the thermodynamic calculations. Some off-gas species were eliminated based on kinetics restrictions evidenced by experimental data and other estimates, and some calcine components and off-gas compounds were eliminated as improbable species (unreliable thermodynamic data). The current Yucca
Modeling and Simulation Tools for Heavy Lift Airships
Hochstetler, Ron; Chachad, Girish; Hardy, Gordon; Blanken, Matthew; Melton, John
2016-01-01
For conventional fixed wing and rotary wing aircraft a variety of modeling and simulation tools have been developed to provide designers the means to thoroughly investigate proposed designs and operational concepts. However, lighter-than-air (LTA) airships, hybrid air vehicles, and aerostats have some important aspects that are different from heavier-than-air (HTA) vehicles. In order to account for these differences, modifications are required to the standard design tools to fully characterize the LTA vehicle design and performance parameters.. To address these LTA design and operational factors, LTA development organizations have created unique proprietary modeling tools, often at their own expense. An expansion of this limited LTA tool set could be accomplished by leveraging existing modeling and simulation capabilities available in the National laboratories and public research centers. Development of an expanded set of publicly available LTA modeling and simulation tools for LTA developers would mitigate the reliance on proprietary LTA design tools in use today. A set of well researched, open source, high fidelity LTA design modeling and simulation tools would advance LTA vehicle development and also provide the analytical basis for accurate LTA operational cost assessments. This paper will present the modeling and analysis tool capabilities required for LTA vehicle design, analysis of operations, and full life-cycle support. A survey of the tools currently available will be assessed to identify the gaps between their capabilities and the LTA industry's needs. Options for development of new modeling and analysis capabilities to supplement contemporary tools will also be presented.
Directory of Open Access Journals (Sweden)
Paul Chun
2003-01-01
Full Text Available We have shown in our published work the existence of a thermodynamic switch in biological systems wherein a change of sign in ΔCp°(Treaction leads to a true negative minimum in the Gibbs free energy change of reaction, and hence, a maximum in the related Keq. We have examined 35 pair-wise, sequence-specific hydrophobic interactions over the temperature range of 273–333 K, based on data reported by Nemethy and Scheraga in 1962. A closer look at a single example, the pair-wise hydrophobic interaction of leucine-isoleucine, will demonstrate the significant differences when the data are analyzed using the Nemethy-Scheraga model or treated by the Planck-Benzinger methodology which we have developed. The change in inherent chemical bond energy at 0 K, ΔH°(T0 is 7.53 kcal mol-1 compared with 2.4 kcal mol-1, while ‹ts› is 365 K as compared with 355 K, for the Nemethy-Scheraga and Planck-Benzinger model, respectively. At ‹tm›, the thermal agitation energy is about five times greater than ΔH°(T0 in the Planck-Benzinger model, that is 465 K compared to 497 K in the Nemethy-Scheraga model. The results imply that the negative Gibbs free energy minimum at a well-defined ‹ts›, where TΔS° = 0 at about 355 K, has its origin in the sequence-specific hydrophobic interactions, which are highly dependent on details of molecular structure. The Nemethy-Scheraga model shows no evidence of the thermodynamic molecular switch that we have found to be a universal feature of biological interactions. The Planck-Benzinger method is the best known for evaluating the innate temperature-invariant enthalpy, ΔH°(T0, and provides for better understanding of the heat of reaction for biological molecules.
Energy Technology Data Exchange (ETDEWEB)
Hageman, Sven; Scharge, Tina; Willms, Thomas
2015-07-15
The report on the development of a thermodynamic data base for selected heavy metals covers the description of experimental methods, the thermodynamic model for chromate, the thermodynamic model for dichromate, the thermodynamic model for manganese (II), the thermodynamic model for cobalt, the thermodynamic model for nickel, the thermodynamic model for copper (I), the thermodynamic model for copper(II), the thermodynamic model for mercury (0) and mercury (I), the thermodynamic model for mercury (III), the thermodynamic model for arsenate.
Ghiorso, M. S.
2014-12-01
Computational thermodynamics (CT) represents a collection of numerical techniques that are used to calculate quantitative results from thermodynamic theory. In the Earth sciences, CT is most often applied to estimate the equilibrium properties of solutions, to calculate phase equilibria from models of the thermodynamic properties of materials, and to approximate irreversible reaction pathways by modeling these as a series of local equilibrium steps. The thermodynamic models that underlie CT calculations relate the energy of a phase to temperature, pressure and composition. These relationships are not intuitive and they are seldom well constrained by experimental data; often, intuition must be applied to generate a robust model that satisfies the expectations of use. As a consequence of this situation, the models and databases the support CT applications in geochemistry and petrology are tedious to maintain as new data and observations arise. What is required to make the process more streamlined and responsive is a computational framework that permits the rapid generation of observable outcomes from the underlying data/model collections, and importantly, the ability to update and re-parameterize the constitutive models through direct manipulation of those outcomes. CT procedures that take models/data to the experiential reference frame of phase equilibria involve function minimization, gradient evaluation, the calculation of implicit lines, curves and surfaces, contour extraction, and other related geometrical measures. All these procedures are the mainstay of image processing analysis. Since the commercial escalation of video game technology, open source image processing libraries have emerged (e.g., VTK) that permit real time manipulation and analysis of images. These tools find immediate application to CT calculations of phase equilibria by permitting rapid calculation and real time feedback between model outcome and the underlying model parameters.
Energy Technology Data Exchange (ETDEWEB)
De Windt, Laurent, E-mail: laurent.dewindt@mines-paristech.fr [MINES ParisTech, PSL Research University, Centre de Géosciences, 35 Rue St-Honoré, 77305 Fontainebleau Cedex (France); Bertron, Alexandra; Larreur-Cayol, Steeves; Escadeillas, Gilles [University of Toulouse, UPS/INSA/LMDC, 135 Av. de Rangueil, 31077 Toulouse Cedex 04 (France)
2015-03-15
Interactions of short-chain organic acids with hydrated cement phases affect structure durability in the agro-food and nuclear waste industries but can also be used to modify cement properties. Most previous studies have been experimental, performed at fixed concentrations and pH, without quantitatively discriminating among polyacidity effects, or complexation and salt precipitation processes. This paper addresses such issues by thermodynamic equilibrium calculations for acetic, citric, oxalic, succinic acids and a simplified hydrated CEM-I. The thermodynamic constants collected from the literature allow the speciation to be modeled over a wide range of pH and concentrations. Citric and oxalic had a stronger chelating effect than acetic acid, while succinic acid was intermediate. Similarly, Ca-citrate and Ca-oxalate salts were more insoluble than Ca-acetate and Ca-succinate salts. Regarding aluminium complexation, hydroxyls, sulfates, and acid competition was highlighted. The exploration of acid mixtures showed the preponderant effect of oxalate and citrate over acetate and succinate.
Bag model of hadrons, dual QCD thermodynamics and Quark-Gluon Plasma
Chandola, H C; Dehnen, H
2015-01-01
Using the grand canonical ensemble formulation of a multi-particle statistical system, the thermodynamical description of the dual QCD has been presented in terms of the bag model of hadrons and analyzed for the quark-gluon plasma phase of hadronic matter. The dual QCD bag construction has been shown to lead to the radial pressure on the bag surface in terms of the vector glueball masses of the magnetically condensed QCD vacuum. Constructing the grand canonical partition function to deal with the quark-gluon plasma phase of the non-strange hadrons, the energy density and the plasma pressure have been derived and used to understand the dynamics of the associated phase transition. The critical temperature for QGP-hadron phase transition has been derived and numerically estimated by using various thermodynamic considerations. A comparison of the values of the critical temperatures for QGP-hadron phase transition with those obtained for the deconfinement-phase transition, has been shown to lead to the relaxation ...
Energy Technology Data Exchange (ETDEWEB)
Serapinas, Petras, E-mail: serapinas@pfi.l [Institute of Theoretical Physics and Astronomy, Vilnius University, A. Gostauto 12, 01108 Vilnius (Lithuania); Salkauskas, Julius; Ezerinskis, Zilvinas; Acus, Arturas [Institute of Theoretical Physics and Astronomy, Vilnius University, A. Gostauto 12, 01108 Vilnius (Lithuania)
2010-01-15
Essentially higher ionization degree of small concentrations of elements in inductively coupled plasma in comparison to the ionization of pure elements is emphasized. This conclusion is used to determine the relative dependence of the sensitivity of the inductively coupled plasma mass spectrometer on the atomic mass. The possibility of evaluation of the ionization temperature and electron density from mass spectrometric signals is proposed. Temperatures about 7000 K and 8000 K were obtained from the ionization ratio dependences on ionization potentials. Electron densities of the order of magnitude 10{sup 15} cm{sup -3}, in excess to the local thermodynamic equilibrium values, follow from the application of the Saha equation to the measurement results and indicate the recombining character of the plasma in the mass spectrometer measurement region. Effects due to additional ionization from matrix were discussed. The effect is largest on minor abundant ionization state components. Matrix effect is restricted to some temperature interval, which depends on the whole matrix composition and the plasma state. The results show that the local thermodynamic equilibrium modeling, if adequately matching the sample composition, can be useful as a quantitative basis for both description of the plasma state and indication of the character of the nonequilibrium effects.
Modelling non-equilibrium thermodynamic systems from the speed-gradient principle
Khantuleva, Tatiana A.; Shalymov, Dmitry S.
2017-03-01
The application of the speed-gradient (SG) principle to the non-equilibrium distribution systems far away from thermodynamic equilibrium is investigated. The options for applying the SG principle to describe the non-equilibrium transport processes in real-world environments are discussed. Investigation of a non-equilibrium system's evolution at different scale levels via the SG principle allows for a fresh look at the thermodynamics problems associated with the behaviour of the system entropy. Generalized dynamic equations for finite and infinite number of constraints are proposed. It is shown that the stationary solution to the equations, resulting from the SG principle, entirely coincides with the locally equilibrium distribution function obtained by Zubarev. A new approach to describe time evolution of systems far from equilibrium is proposed based on application of the SG principle at the intermediate scale level of the system's internal structure. The problem of the high-rate shear flow of viscous fluid near the rigid plane plate is discussed. It is shown that the SG principle allows closed mathematical models of non-equilibrium processes to be constructed. This article is part of the themed issue 'Horizons of cybernetical physics'.
Energy Technology Data Exchange (ETDEWEB)
Huang Mingxin; Rivera-Diaz-del-Castillo, Pedro E J; Zwaag, Sybrand van der [Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS, Delft (Netherlands); Bouaziz, Olivier, E-mail: mingxin.huang@arcelormittal.com [ArcelorMittal Maizieres, Research and Development, Voie Romaine-BP30320, 57283 Maizieres-les-Metz Cedex (France)
2009-07-15
Based on the theory of irreversible thermodynamics, the present work proposes a dislocation-based model to describe the plastic deformation of FCC metals over wide ranges of strain rates. The stress-strain behaviour and the evolution of the average dislocation density are derived. It is found that there is a transitional strain rate ({approx} 10{sup 4} s{sup -1}) over which the phonon drag effects appear, resulting in a significant increase in the flow stress and the average dislocation density. The model is applied to pure Cu deformed at room temperature and at strain rates ranging from 10{sup -5} to 10{sup 6} s{sup -1} showing good agreement with experimental results.
Thermodynamics of the two-dimensional XY model from functional renormalization
Jakubczyk, Pawel
2016-01-01
We solve the nonperturbative renormalization-group flow equations for the two-dimensional XY model at the truncation level of the (complete) second-order derivative expansion. We compute the thermodynamic properties in the high-temperature phase and compare the non-universal features specific to the XY model with results from Monte Carlo simulations. In particular, we study the position and magnitude of the specific heat peak as a function of temperature. The obtained results compare well with Monte Carlo simulations. We additionally gauge the accuracy of simplified nonperturbative renormalization-group treatments relying on $\\phi^4$-type truncations. Our computation indicates that such an approximation is insufficient in the high-$T$ phase and a correct analysis of the specific heat profile requires account of an infinite number of interaction vertices.
The Disc-Jet Symbiosis Emerges: Modeling the Emission of Sagittarius A* with Electron Thermodynamics
Ressler, Sean M; Quataert, Eliot; Gammie, Charles F
2016-01-01
We calculate the radiative properties of Sagittarius A* -- spectral energy distribution, variability, and radio-infrared images -- using the first 3D, physically motivated black hole accretion models that directly evolve the electron thermodynamics in general relativistic MHD simulations. These models reproduce the coupled disc-jet structure for the emission favored by previous phenomenological analytic and numerical works. More specifically, we find that the low frequency radio emission is dominated by emission from a polar outflow while the emission above 100 GHz is dominated by the inner region of the accretion disc. The latter produces time variable near infrared (NIR) and X-ray emission, with frequent flaring events (including IR flares without corresponding X-ray flares and IR flares with weak X-ray flares). The photon ring is clearly visible at 230 GHz and 2 microns, which is encouraging for future horizon-scale observations. We also show that anisotropic electron thermal conduction along magnetic fiel...
von Bertalanffy 1.0: a COBRA toolbox extension to thermodynamically constrain metabolic models.
Fleming, Ronan M T; Thiele, Ines
2011-01-01
In flux balance analysis of genome scale stoichiometric models of metabolism, the principal constraints are uptake or secretion rates, the steady state mass conservation assumption and reaction directionality. Here, we introduce an algorithmic pipeline for quantitative assignment of reaction directionality in multi-compartmental genome scale models based on an application of the second law of thermodynamics to each reaction. Given experimental or computationally estimated standard metabolite species Gibbs energy and metabolite concentrations, the algorithms bounds reaction Gibbs energy, which is transformed to in vivo pH, temperature, ionic strength and electrical potential. This cross-platform MATLAB extension to the COnstraint-Based Reconstruction and Analysis (COBRA) toolbox is computationally efficient, extensively documented and open source. http://opencobra.sourceforge.net.
FINITE TIME THERMODYNAMIC MODELING AND ANALYSIS FOR AN IRREVERSIBLE ATKINSON CYCLE
Directory of Open Access Journals (Sweden)
Yanlin Ge
2010-01-01
Full Text Available Performance of an air-standard Atkinson cycle is analyzed by using finite-time thermodynamics. The irreversible cycle model which is more close to practice is founded. In this model, the non-linear relation between the specific heats of working fluid and its temperature, the friction loss computed according to the mean velocity of the piston, the internal irreversibility described by using the compression and expansion efficiencies, and heat transfer loss are considered. The relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, as well as the optimal relation between power output and the efficiency of the cycle are derived by detailed numerical examples. Moreover, the effects of internal irreversibility, heat transfer loss and friction loss on the cycle performance are analyzed. The results obtained in this paper may provide guidelines for the design of practical internal combustion engines.
Exact thermodynamics and phase diagram of integrable t-J model with chiral interaction
Tavares, T. S.; Ribeiro, G. A. P.
2016-09-01
We study the phase diagram and finite temperature properties of an integrable generalization of the one-dimensional super-symmetric t-J model containing interactions explicitly breaking parity-time reversal (PT) symmetries. To this purpose, we apply the quantum transfer matrix method which results in a finite set of non-linear integral equations. We obtain numerical solutions to these equations leading to results for thermodynamic quantities as a function of temperature, magnetic field, particle density and staggering parameter. Studying the maxima lines of entropy at low but non zero temperature reveals the phase diagram of the model. There are ten different phases which we may classify in terms of the qualitative behaviour of auxiliary functions, closely related to the dressed energy functions.
Crossover and thermodynamic representation in the extended η model for fractal growth
Nagatani, Takashi; Stanley, H. Eugene
1990-10-01
The η model for the dielectric breakdown is extended to the case where double power laws apply. It is shown that a crossover phenomenon between the diffusion-limited aggregation (DLA) fractal and the η fractal occurs in the extended η model. Through the use of the dimensional analysis, a dimensionless parameter is found to govern the crossover. It is shown that when η1 the inverse crossover from the η fractal to the DLA fractal appears. It is also shown that the crossover radius is controlled by changing the applied field. The global flow diagram in the two-parameter space is obtained by using a two-parameter position-space renormalization-group approach. The crossover exponent and the crossover radius are calculated. The crossover phenomenon is described in terms of a thermodynamic representation of the two-phase equilibrium.
Thermodynamics of the two-dimensional XY model from functional renormalization.
Jakubczyk, P; Eberlein, A
2016-06-01
We solve the nonperturbative renormalization-group flow equations for the two-dimensional XY model at the truncation level of the (complete) second-order derivative expansion. We compute the thermodynamic properties in the high-temperature phase and compare the nonuniversal features specific to the XY model with results from Monte Carlo simulations. In particular, we study the position and magnitude of the specific-heat peak as a function of temperature. The obtained results compare well with Monte Carlo simulations. We additionally gauge the accuracy of simplified nonperturbative renormalization-group treatments relying on ϕ^{4}-type truncations. Our computation indicates that such an approximation is insufficient in the high-T phase and a correct analysis of the specific-heat profile requires account of an infinite number of interaction vertices.
A Thermodynamic Model of Monovalent Cation Homeostasis in the Yeast Saccharomyces cerevisiae.
Directory of Open Access Journals (Sweden)
Susanne Gerber
2016-01-01
Full Text Available Cationic and heavy metal toxicity is involved in a substantial number of diseases in mammals and crop plants. Therefore, the understanding of tightly regulated transporter activities, as well as conceiving the interplay of regulatory mechanisms, is of substantial interest. A generalized thermodynamic description is developed for the complex interplay of the plasma membrane ion transporters, membrane potential and the consumption of energy for maintaining and restoring specific intracellular cation concentrations. This concept is applied to the homeostasis of cation concentrations in the yeast cells of S. cerevisiae. The thermodynamic approach allows to model passive ion fluxes driven by the electrochemical potential differences, but also primary or secondary active transport processes driven by the inter- play of different ions (symport, antiport or by ATP consumption (ATPases. The model-confronted with experimental data-reproduces the experimentally observed potassium and proton fluxes induced by the external stimuli KCl and glucose. The estimated phenomenological constants combine kinetic parameters and transport coefficients. These are in good agreement with the biological understanding of the transporters thus providing a better understanding of the control exerted by the coupled fluxes. The model predicts the flux of additional ion species, like e.g. chloride, as a potential candidate for counterbalancing positive charges. Furthermore, the effect of a second KCl stimulus is simulated, predicting a reduced cellular response for cells that were first exposed to a high KCl stimulus compared to cells pretreated with a mild KCl stimulus. By describing the generalized forces that are responsible for a given flow, the model provides information and suggestions for new experiments. Furthermore, it can be extended to other systems such as e.g. Candida albicans, or selected plant cells.
A Thermodynamic Model of Monovalent Cation Homeostasis in the Yeast Saccharomyces cerevisiae.
Gerber, Susanne; Fröhlich, Martina; Lichtenberg-Fraté, Hella; Shabala, Sergey; Shabala, Lana; Klipp, Edda
2016-01-01
Cationic and heavy metal toxicity is involved in a substantial number of diseases in mammals and crop plants. Therefore, the understanding of tightly regulated transporter activities, as well as conceiving the interplay of regulatory mechanisms, is of substantial interest. A generalized thermodynamic description is developed for the complex interplay of the plasma membrane ion transporters, membrane potential and the consumption of energy for maintaining and restoring specific intracellular cation concentrations. This concept is applied to the homeostasis of cation concentrations in the yeast cells of S. cerevisiae. The thermodynamic approach allows to model passive ion fluxes driven by the electrochemical potential differences, but also primary or secondary active transport processes driven by the inter- play of different ions (symport, antiport) or by ATP consumption (ATPases). The model-confronted with experimental data-reproduces the experimentally observed potassium and proton fluxes induced by the external stimuli KCl and glucose. The estimated phenomenological constants combine kinetic parameters and transport coefficients. These are in good agreement with the biological understanding of the transporters thus providing a better understanding of the control exerted by the coupled fluxes. The model predicts the flux of additional ion species, like e.g. chloride, as a potential candidate for counterbalancing positive charges. Furthermore, the effect of a second KCl stimulus is simulated, predicting a reduced cellular response for cells that were first exposed to a high KCl stimulus compared to cells pretreated with a mild KCl stimulus. By describing the generalized forces that are responsible for a given flow, the model provides information and suggestions for new experiments. Furthermore, it can be extended to other systems such as e.g. Candida albicans, or selected plant cells.
Tool for physics beyond the standard model
Newby, Christopher A.
The standard model (SM) of particle physics is a well studied theory, but there are hints that the SM is not the final story. What the full picture is, no one knows, but this thesis looks into three methods useful for exploring a few of the possibilities. To begin I present a paper by Spencer Chang, Nirmal Raj, Chaowaroj Wanotayaroj, and me, that studies the Higgs boson. The scalar particle first seen in 2012 may be the vanilla SM version, but there is some evidence that its couplings are different than predicted. By means of increasing the Higgs' coupling to vector bosons and fermions, we can be more consistent with the data. Next, in a paper by Spencer Chang, Gabriel Barello, and me, we elaborate on a tool created to study dark matter (DM) direct detection. The original work by Anand. et al. focused on elastic dark matter, whereas we extended this work to include the in elastic case, where different DM mass states enter and leave the collision. We also examine several direct detection experiments with our new framework to see if DAMA's modulation can be explained while avoiding the strong constraints imposed by the other experiments. We find that there are several operators that can do this. Finally, in a paper by Spencer Chang, Gabriel Barello, and me, we study an interesting phenomenon know as kinetic mixing, where two gauge bosons can share interactions with particles even though these particles aren't charged under both gauge groups. This, in and of itself, is not new, but we discuss a different method of obtaining this mixing where instead of mixing between two Abelian groups one of the groups is Nonabelian. Using this we then see that there is an inherent mass scale in the mixing strength; something that is absent in the Abelian-Abelian case. Furthermore, if the Nonabelian symmetry is the SU(2)L of the SM then the mass scale of the physics responsible for the mixing is about 1 TeV, right around the sweet spot for detection at the LHC. This dissertation
Salleh, M. S.; Omar,M.Z.; J. Syarif; M. N. Mohammed
2012-01-01
Semisolid metal (SSM) processing or Thixoforming is a new method for forming alloys in the semisolid state to near net shaped products. All the alloys which have been used to date for thixoforming were developed originally for either casting or forging operations. Thus, there is a lack of specific alloys for semi solid processing that present good fluidity, low viscosity and small grain size. Thermodynamic calculation software, such as Java-based Material Properties (JMatPro), provides a tool...
Incorporation of Electrical Systems Models Into an Existing Thermodynamic Cycle Code
Freeh, Josh
2003-01-01
Integration of entire system includes: Fuel cells, motors, propulsors, thermal/power management, compressors, etc. Use of existing, pre-developed NPSS capabilities includes: 1) Optimization tools; 2) Gas turbine models for hybrid systems; 3) Increased interplay between subsystems; 4) Off-design modeling capabilities; 5) Altitude effects; and 6) Existing transient modeling architecture. Other factors inclde: 1) Easier transfer between users and groups of users; 2) General aerospace industry acceptance and familiarity; and 3) Flexible analysis tool that can also be used for ground power applications.
Haack, Lukas; Peniche, Ricardo; Sommer, Lutz; Kather, Alfons
2017-06-01
At early project stages, the main CSP plant design parameters such as turbine capacity, solar field size, and thermal storage capacity are varied during the techno-economic optimization to determine most suitable plant configurations. In general, a typical meteorological year with at least hourly time resolution is used to analyze each plant configuration. Different software tools are available to simulate the annual energy yield. Software tools offering a thermodynamic modeling approach of the power block and the CSP thermal cycle, such as EBSILONProfessional®, allow a flexible definition of plant topologies. In EBSILON, the thermodynamic equilibrium for each time step is calculated iteratively (quasi steady state), which requires approximately 45 minutes to process one year with hourly time resolution. For better presentation of gradients, 10 min time resolution is recommended, which increases processing time by a factor of 5. Therefore, analyzing a large number of plant sensitivities, as required during the techno-economic optimization procedure, the detailed thermodynamic simulation approach becomes impracticable. Suntrace has developed an in-house CSP-Simulation tool (CSPsim), based on EBSILON and applying predictive models, to approximate the CSP plant performance for central receiver and parabolic trough technology. CSPsim significantly increases the speed of energy yield calculations by factor ≥ 35 and has automated the simulation run of all predefined design configurations in sequential order during the optimization procedure. To develop the predictive models, multiple linear regression techniques and Design of Experiment methods are applied. The annual energy yield and derived LCOE calculated by the predictive model deviates less than ±1.5 % from the thermodynamic simulation in EBSILON and effectively identifies the optimal range of main design parameters for further, more specific analysis.
Directory of Open Access Journals (Sweden)
Gandova V.
2013-01-01
Full Text Available The thermochemical properties of metals and alloys are essential for the chemists to invent and improve metallurgical and materials’ design processes. However, the properties of multicomponent systems are still scarcely known due to experimental difficulties and the large number of related systems. Thus, the modelling of some thermodynamic properties would be advantageous when experimental data are missing. Considering mentioned facts, geometric models to estimate some thermodynamic properties for the liquid phase of the Ni-Bi-Zn systems. The calculations have been performed in a wide temperature range (1000-2000 K. Ternary interaction parameters for the liquid phase allowing molar Gibbs excess energy calculation have been determined.
Computation of bone remodelling after Duracon knee arthroplasty using a thermodynamic-based model.
Bougherara, H; Nazgooei, S; Sayyidmousavi, A; Marsik, F; Marík, I A
2011-07-01
The present study utilizes a recently developed literature model for the bone remodelling process to predict the evolution of bone density following Duracon total knee arthroplasty (TKA). In this model, which is based on chemical kinetics and irreversible thermodynamics, bone is treated as a self-organizing system capable of exchanging matter, energy, and entropy with its surroundings. Unlike previous models in which mechanical loading is regarded as the only stimulus for bone remodelling, the present model establishes a unique coupling between mechanical loading and the chemical reactions involved in the process of bone remodelling. This model was incorporated into the finite element software ANSYS by means of a macro to compute density distribution in distal femoral bone both before and after TKA. Consistent with dual-energy X-ray absorptiometry (DEXA) scans reported in the literature, the results showed that the most severe bone loss occurs in the anterior region of the distal femur and that there is more bone resorption in the lateral than the medial condyle following TKA. Furthermore, the bone density distribution predicted using the present model showed a gradual and uniform pattern and thus a more realistic bone evolution contrary to the strain energy density model, where there is no gradual bone density evolution.
Energy Technology Data Exchange (ETDEWEB)
Venson, Giuliano Gardolinski [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Engenharia Mecanica], e-mail: venson@ufmg.br; Barros, Jose Eduardo Mautone; Pereira, Josemar Figueiredo [Centro Federal de Educacao Tecnologica de Minas Gerais (CEFET-MG), Belo Horizonte, MG (Brazil)], e-mail: mautone@des.cefetmg.br, e-mail: josemar_cefet@yahoo.com.br
2006-07-01
This work presents the modeling of a gas microturbine power generator. The microturbine consists in a small thermo-electrical power unit, design for combined heat and power generation. The unit has an electric generator, coaxially connected with a turbocharger, which one is driven by a fuel burner. The system also incorporates an air regenerator, used for pre-heat the combustion air, and a heat exchanger, used for water heating. The objective of the modeling is the attainment of the electrical performance and the operational limits for the microturbine in function of the subsystems operational conditions. The modeling is based on the first law of the thermodynamic, using specific models for each component. In the combustion chamber is used a model that takes the fuel injection properties, as absolute pressure and temperature. A semi-empirical model, based in the modified Euler equation, is used in the turbocharger. In the air regenerator and heat exchanger, the method of mean logarithmic temperature difference is used. Through the modeling of a commercial microturbine, reference values obtained were used in some subsystems of a new microturbine. The results for this new microturbine in development, based in automotive turbochargers, indicate a nominal electrical power of 38 kW with electrical efficiency of 33% and global efficiency of 73%. (author)
Directory of Open Access Journals (Sweden)
Wassim M. Haddad
2014-07-01
Full Text Available Advances in neuroscience have been closely linked to mathematical modeling beginning with the integrate-and-fire model of Lapicque and proceeding through the modeling of the action potential by Hodgkin and Huxley to the current era. The fundamental building block of the central nervous system, the neuron, may be thought of as a dynamic element that is “excitable”, and can generate a pulse or spike whenever the electrochemical potential across the cell membrane of the neuron exceeds a threshold. A key application of nonlinear dynamical systems theory to the neurosciences is to study phenomena of the central nervous system that exhibit nearly discontinuous transitions between macroscopic states. A very challenging and clinically important problem exhibiting this phenomenon is the induction of general anesthesia. In any specific patient, the transition from consciousness to unconsciousness as the concentration of anesthetic drugs increases is very sharp, resembling a thermodynamic phase transition. This paper focuses on multistability theory for continuous and discontinuous dynamical systems having a set of multiple isolated equilibria and/or a continuum of equilibria. Multistability is the property whereby the solutions of a dynamical system can alternate between two or more mutually exclusive Lyapunov stable and convergent equilibrium states under asymptotically slowly changing inputs or system parameters. In this paper, we extend the theory of multistability to continuous, discontinuous, and stochastic nonlinear dynamical systems. In particular, Lyapunov-based tests for multistability and synchronization of dynamical systems with continuously differentiable and absolutely continuous flows are established. The results are then applied to excitatory and inhibitory biological neuronal networks to explain the underlying mechanism of action for anesthesia and consciousness from a multistable dynamical system perspective, thereby providing a
Molecular Thermodynamic Model for Polyelectrolyte Solutions with Added Salts%含盐聚电解质溶液的分子热力学模型
Institute of Scientific and Technical Information of China (English)
张波; 蔡钧; 刘洪来; 胡英
2002-01-01
A molecular thermodynamic model of polyelectrolyte developed previously was extended to polyelectrolyte solutions with added salts. Thermodynamic properties, such as activity coefficients of polyelectrolytes or added salts and osmotic coefficients of solvent, of a number of aqueous mixtures of polyelectrolytes and salts are analyzed with the proposed model. Successful correlation is obtained in the range of moderate or higher polyion concentration. For the same sample, thermodynamic properties of polyelectrolytes with and without simple electrolytes can be predicted mutually using parameters from regression data.
Energy Technology Data Exchange (ETDEWEB)
Bencze, L., E-mail: bencze@chem.elte.hu [Institute for Energy and Climate Research (IEK-2), Forschungszentrum Jülich GmbH, D-52425 Jülich (Germany); Eötvös Loránd University, Dept. of Physical Chemistry, H-1117 Budapest, Pázmány Péter sétány 1/A (Hungary); Henriques, D. [Institute for Energy and Climate Research (IEK-2), Forschungszentrum Jülich GmbH, D-52425 Jülich (Germany); Motalov, V. [Institute for Energy and Climate Research (IEK-2), Forschungszentrum Jülich GmbH, D-52425 Jülich (Germany); Department of Physics, Ivanovo State University of Chemistry and Technology, Sheremetevsky av.7, 153000 Ivanovo (Russian Federation); Markus, T. [Institute for Energy and Climate Research (IEK-2), Forschungszentrum Jülich GmbH, D-52425 Jülich (Germany)
2014-09-01
Highlights: • The experimental KEMS data fit well with the Redlich–Kister sub-regular solution model applied to Li–Sn melt. • The Redlich–Kister binary interaction L-parameters of the Li–Sn melt were provided in this work. • The experimental KEMS data fit well with the ideally associated mixture model, too. • The quantitative associate composition of the Li–Sn melt was given. • The thermodynamic properties of the associate-forming reactions were also provided. - Abstract: The mixing thermodynamic properties of liquid Li–Sn system, determined previously by Knudsen effusion mass spectrometry (KEMS), were successfully fitted to both Redlich–Kister (RK) sub-regular mixture and ideally associated mixture (IAMT) models. The RK binary interaction L parameters, as a function of temperature in the CALPHAD-type functional form, were obtained as follows: L{sup (0)}=-(108580±0.00171)+(16.4±1.6·10{sup -5})·T+(1.96496·10{sup -9}±2.03133·10{sup -6}) ·T·ln(T) L{sup (1)}=-(96600±4700)+(3.3±43.0)·T+(4.4±5.6)·T·ln(T) L{sup (2)}=-(64670±190)-(44.4±1.7)·T+(8.44±0.22)·T·ln(T) L{sup (3)}=-(20900±1500)-(29±14)·T+(4.3±1.8)·T·ln(T) The former literature data provided only qualitative information on possible liquid associates but no quantitative associate composition was given as a function of the sample composition and temperature. The experimental KEMS data in the composition range X{sub Li} = 0 to ∼0.7 fit well with the Li(l) + Sn(l) + LiSn(l) + LiSn{sub 2}(l) + Li{sub 2}Sn(l) associate model. At X{sub Li} > 0.7 no associate variations – including further associate variants such as Li{sub 4}Sn(l) etc. – could be fitted to the KEMS data. Nevertheless, in this work the Li(l) + Sn(l) + LiSn(l) + LiSn{sub 2}(l) + Li{sub 2}Sn(l) + Li{sub 4}Sn(l) + Li{sub 9}Sn(l) associate model was successfully fitted to the thermodynamic data of a selected literature study over the complete composition range. The thermodynamic data of the associate
Large scale experiments as a tool for numerical model development
DEFF Research Database (Denmark)
Kirkegaard, Jens; Hansen, Erik Asp; Fuchs, Jesper;
2003-01-01
for improvement of the reliability of physical model results. This paper demonstrates by examples that numerical modelling benefits in various ways from experimental studies (in large and small laboratory facilities). The examples range from very general hydrodynamic descriptions of wave phenomena to specific......Experimental modelling is an important tool for study of hydrodynamic phenomena. The applicability of experiments can be expanded by the use of numerical models and experiments are important for documentation of the validity of numerical tools. In other cases numerical tools can be applied...... hydrodynamic interaction with structures. The examples also show that numerical model development benefits from international co-operation and sharing of high quality results....
Advanced reach tool (ART) : Development of the mechanistic model
Fransman, W.; Tongeren, M. van; Cherrie, J.W.; Tischer, M.; Schneider, T.; Schinkel, J.; Kromhout, H.; Warren, N.; Goede, H.; Tielemans, E.
2011-01-01
This paper describes the development of the mechanistic model within a collaborative project, referred to as the Advanced REACH Tool (ART) project, to develop a tool to model inhalation exposure for workers sharing similar operational conditions across different industries and locations in Europe. T
Storm Water Management Model Climate Adjustment Tool (SWMM-CAT)
The US EPA’s newest tool, the Stormwater Management Model (SWMM) – Climate Adjustment Tool (CAT) is meant to help municipal stormwater utilities better address potential climate change impacts affecting their operations. SWMM, first released in 1971, models hydrology and hydrauli...
pycalphad: CALPHAD-based Computational Thermodynamics in Python
Directory of Open Access Journals (Sweden)
Richard Otis
2017-01-01
Full Text Available The pycalphad software package is a free and open-source Python library for designing thermodynamic models, calculating phase diagrams and investigating phase equilibria using the CALPHAD method. It provides routines for reading thermodynamic databases and solving the multi-component, multi-phase Gibbs energy minimization problem. The pycalphad software project advances the state of thermodynamic modeling by providing a flexible yet powerful interface for manipulating CALPHAD data and models. The key feature of the software is that the thermodynamic models of individual phases and their associated databases can be programmatically manipulated and overridden at run-time without modifying any internal solver or calculation code. Because the models are internally decoupled from the equilibrium solver and the models themselves are represented symbolically, pycalphad is an ideal tool for CALPHAD database development and model prototyping.
Qi, Weihong
2016-09-20
Conventional thermodynamics for bulk substances encounters challenges when one considers materials on the nanometer scale. Quantities such as entropy, enthalpy, free energy, melting temperature, ordering temperature, Debye temperature, and specific heat no longer remain constant but change with the crystal dimension, size, and morphology. Often, one phenomenon is associated with a variety of theories from different perspectives. Still, a model that can reconcile the size and shape dependence of the thermal properties of the nanoscaled substances remains one of the goals of nanoscience and nanotechnology. This Account highlights the nanoscopic thermodynamics for nanoparticles, nanowires, and nanofilms, with particular emphasis on the bond energy model. The central idea is that the atomic cohesive energy determines the thermodynamic performance of a substance and the cohesive energy varies with the atomic coordination environment. It is the cohesive energy difference between the core and the shell that dictates the nanoscopic thermodynamics. This bond energy model rationalizes the following: (i) how the surface dangling bonds depress the melting temperature, entropy, and enthalpy; (ii) how the order-disorder transition of the nanoparticles depends on particle size and how their stability may vary when they are embedded in an appropriate matrix; (iii) predictions of the existence of face-centered cubic structures of Ti, Zr, and Hf at small size; (iv) how two elements that are immiscible in the bulk can form an alloy on the nanoscale, where the critical size can be predicted. The model has enabled us to reproduce the size and shape dependence of a number of physical properties, such as melting temperature, melting entropy, melting enthalpy, ordering temperature, Gibbs free energy, and formation heat, among others, for materials such as Pd, Au, Ag, Cu, Ni, Sn, Pb, In, Bi, Al, Ti, Zr, Hf, In-Al, Ag-Ni, Co-Pt, Cu-Ag, Cu-Ni, Au-Ni, Ag-Pt, and Au-Pt on the nanometer scale
Quantum phase transitions and thermodynamics of the power-law Kondo model
Mitchell, Andrew K.; Vojta, Matthias; Bulla, Ralf; Fritz, Lars
2013-11-01
We revisit the physics of a Kondo impurity coupled to a fermionic host with a diverging power-law density of states near the Fermi level, ρ(ω)˜|ω|r, with exponent -1
A non-equilibrium thermodynamic model for tumor extracellular matrix with enzymatic degradation
Xue, Shi-Lei; Li, Bo; Feng, Xi-Qiao; Gao, Huajian
2017-07-01
The extracellular matrix (ECM) of a solid tumor not only affords scaffolding to support tumor architecture and integrity but also plays an essential role in tumor growth, invasion, metastasis, and therapeutics. In this paper, a non-equilibrium thermodynamic theory is established to study the chemo-mechanical behaviors of tumor ECM, which is modeled as a poroelastic polyelectrolyte consisting of a collagen network and proteoglycans. By using the principle of maximum energy dissipation rate, we deduce a set of governing equations for drug transport and mechanosensitive enzymatic degradation in ECM. The results reveal that osmosis is primarily responsible for the compression resistance of ECM. It is suggested that a well-designed ECM degradation can effectively modify the tumor microenvironment for improved efficiency of cancer therapy. The theoretical predictions show a good agreement with relevant experimental observations. This study aimed to deepen our understanding of tumor ECM may be conducive to novel anticancer strategies.
Thermodynamics and dynamical properties of the KH2PO4 type ferroelectric compounds. A unified model
Directory of Open Access Journals (Sweden)
R.R. Levitskii
2009-01-01
Full Text Available Within the framework of the proposed unified proton ordering model for the ferroelectric compounds of the KH2PO4 family, in the four-particle cluster approximation for the short-range interactions and mean field approximation for the long-range interactions, we calculate thermodynamic and longitudinal dynamic characteristics of the KD2PO4 type ferroelectrics and ND4D2PO4 type antiferroelectrics. Calculations for partially deuterated K(H1-xDx2PO4 type ferroelectrics and N(H1-xDx4(H1-xDx2PO4 type antiferroelectrics are performed within the mean crystal approximation. It is shown that at the proper choice of the theory parameters, a good quantitative description of experimental data for the KH2PO4 family crystals is obtained.
Zhu, Qi-zhi; Shao, Jian-fu; Kondo, Djimedo
2008-04-01
In the present Note, we present a discrete thermodynamic approach for modeling coupled anisotropic plastic flow and damage evolution in geomaterials. The basic idea is to extend the widely-used isotropic coupled elastoplastic damage formulation to the case with induced anisotropy using a discrete approach. The total plastic strain is considered as the consequence of frictional sliding in weak sliding planes randomly distributed in the elastic solid matrix. The effective elastic tensor of damaged material is determined using damage variable associated with each family of weak sliding planes. An example of application is shown for a typical semi-brittle rock. To cite this article: Q.-Z. Zhu et al., C. R. Mecanique 336 (2008).
Meteorites and the RNA World: A Thermodynamic Model of Nucleobase Synthesis within Planetesimals
Pearce, Ben K D
2016-01-01
The possible meteorite parent body origin of Earth's pregenetic nucleobases is substantiated by the guanine (G), adenine (A) and uracil (U) measured in various meteorites. Cytosine (C) and thymine (T) however are absent in meteorites, making the emergence of a RNA and later RNA/DNA/protein world problematic. We investigate the meteorite parent body (planetesimal) origin of all nucleobases by computationally modeling 18 reactions that potentially contribute to nucleobase formation in such environments. Out of this list, we identify the two most important reactions for each nucleobase and find that these involve small molecules such as HCN, CO, NH3, and water that ultimately arise from the protoplanetary disks in which planetesimals are built. The primary result of this study is that cytosine is unlikely to persist within meteorite parent bodies due to aqueous deamination. Thymine has a thermodynamically favourable reaction pathway from uracil, formaldehyde and formic acid, but likely did not persist within pla...
Design and off-design thermodynamic model of a gas turbine for performance prediction
Energy Technology Data Exchange (ETDEWEB)
Monteiro, Ulisses A. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE). Lab. de Ensaios de Modelos de Engenharia (LEME)]. E-mail: ulisses@peno.coppe.ufrj.br; Belchior, Carlos Rodrigues Pereira [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE). Lab. de Maquinas Termicas (LMT)]. E-mail: belchior@peno.coppe.ufrj.br
2008-07-01
There are some types of faults that do not leave 'signatures' in the vibration spectrum of a gas turbine. These faults can only be detected by other analysis techniques. One of these techniques is the gas turbine performance analysis or gas path analysis which relates the efficiency, mass flow, temperature, pressure, fuel consumption and power to the gas turbine faults. In this paper the methodology used in the development of a thermodynamic model that simulates the design and off-design operation of a gas turbine with a free power turbine will be presented. The results obtained are used to predict the gas turbine performance in both design and off-design operation point, and also to simulate some types of faults. (author)
Institute of Scientific and Technical Information of China (English)
CHENG Yan; TU Ya-Jing; ZENG Zhao-Yi; GOU Qing-Quan
2008-01-01
Shell model molecular dynamic simulation with interatomic pair potential is utilized to investigate the elastic and thermodynamic properties of gallium nitride with hexagonal wurtzite structure (w-GaN) at high pressure. The calculated elastic constants Cij at zero pressure and 300 K agree well with the experimental data and other calculated values. Meanwhile, the dependences of the relative volume V/Vo, elastic constants Cij, entropy S, enthalpy H, and heat capacities Cv and Cp on pressure are successfully obtained. From the elastic constants obtained, we also calculate the shear modulus G, bulk modulus B, Young's modulus E, Poisson's ratio v, Debye temperature ΘD, and shear anisotropic factor Ashear on pressures.
Stochastic Thermodynamics of Learning
Goldt, Sebastian; Seifert, Udo
2017-01-01
Virtually every organism gathers information about its noisy environment and builds models from those data, mostly using neural networks. Here, we use stochastic thermodynamics to analyze the learning of a classification rule by a neural network. We show that the information acquired by the network is bounded by the thermodynamic cost of learning and introduce a learning efficiency η ≤1 . We discuss the conditions for optimal learning and analyze Hebbian learning in the thermodynamic limit.
Stochastic Thermodynamics of Learning
Goldt, Sebastian
2016-01-01
Virtually every organism gathers information about its noisy environment and builds models from that data, mostly using neural networks. Here, we use stochastic thermodynamics to analyse the learning of a classification rule by a neural network. We show that the information acquired by the network is bounded by the thermodynamic cost of learning and introduce a learning efficiency $\\eta\\le1$. We discuss the conditions for optimal learning and analyse Hebbian learning in the thermodynamic limit.
Dynamic wind turbine models in power system simulation tool
DEFF Research Database (Denmark)
Hansen, A.; Jauch, Clemens; Soerensen, P.
The present report describes the dynamic wind turbine models implemented in the power system simulation tool DIgSILENT. The developed models are a part of the results of a national research project, whose overall objective is to create a model database in different simulation tools. The report...... provides a description of the wind turbine modelling, both at a component level and at a system level....
The Use of VMD Data/Model to Test Different Thermodynamic Models for Vapour-Liquid Equilibrium
DEFF Research Database (Denmark)
Abildskov, Jens; Azquierdo-Gil, M.A.; Jonsson, Gunnar Eigil
2004-01-01
Vacuum membrane distillation (VMD) has been studied as a separation process to remove volatile organic compounds from aqueous streams. A vapour pressure difference across a microporous hydrophobic membrane is the driving force for the mass transport through the membrane pores (this transport take...... values; membrane type: PTFE/PP/PVDF; feed flow rate; feed temperature. A comparison is made between different thermodynamic models for calculating the vapour-liquid equilibrium at the membrane/pore interface. (C) 2004 Elsevier B.V. All rights reserved....
Modeling Languages: metrics and assessing tools
Fonte, Daniela; Boas, Ismael Vilas; Azevedo, José; Peixoto, José João; Faria, Pedro; Silva, Pedro; Sá, Tiago de, 1990-; Costa, Ulisses; da Cruz, Daniela; Henriques, Pedro Rangel
2012-01-01
Any traditional engineering field has metrics to rigorously assess the quality of their products. Engineers know that the output must satisfy the requirements, must comply with the production and market rules, and must be competitive. Professionals in the new field of software engineering started a few years ago to define metrics to appraise their product: individual programs and software systems. This concern motivates the need to assess not only the outcome but also the process and tools em...
The mathematical and computer modeling of the worm tool shaping
Panchuk, K. L.; Lyashkov, A. A.; Ayusheev, T. V.
2017-06-01
Traditionally mathematical profiling of the worm tool is carried out on the first T. Olivier method, known in the theory of gear gearings, with receiving an intermediate surface of the making lath. It complicates process of profiling and its realization by means of computer 3D-modeling. The purpose of the work is the improvement of mathematical model of profiling and its realization based on the methods of 3D-modeling. Research problems are: receiving of the mathematical model of profiling which excludes the presence of the making lath in it; realization of the received model by means of frame and superficial modeling; development and approbation of technology of solid-state modeling for the solution of the problem of profiling. As the basic, the kinematic method of research of the mutually envelope surfaces is accepted. Computer research is executed by means of CAD based on the methods of 3D-modeling. We have developed mathematical model of profiling of the worm tool; frame, superficial and solid-state models of shaping of the mutually enveloping surfaces of the detail and the tool are received. The offered mathematical models and the technologies of 3D-modeling of shaping represent tools for theoretical and experimental profiling of the worm tool. The results of researches can be used at design of metal-cutting tools.
Wexler, David B.; Hollweg, Joseph V.; Jensen, Elizabeth; Lionello, Roberto; Macneice, Peter J.; Coster, Anthea J.
2017-08-01
Study of coronal MHD wave energetics relies upon accurate representation of plasma particle number densities (ne) and magnetic field strengths. In the lower corona, these parameters are obtained indirectly, and typically presented as empirical equations as a function of heliocentric radial distance (solar offset, SO). The development of coronal global models using synoptic solar surface magnetogram inputs has provided refined characterization of the coronal plasma organization and magnetic field. We present a cross-analysis between a MHD thermodynamic simulation and Faraday rotation (FR) observations over SO 1.63-1.89 solar radii (Rs) near solar minimum. MESSENGER spacecraft radio signals with a line of sight (LOS) passing through the lower corona were recorded in dual polarization using the Green Bank Telescope in November 2009. Polarization position angle changes were obtained from Stokes parameters. The magnetic field vector (B) and ne along the LOS were obtained from a MHD thermodynamic simulation provided by the Community Coordinated Modeling Center. The modeled FR was computed as the integrated product of ne and LOS-aligned B component. The observations over the given SO range yielded an FR change of 7 radians. The simulation reproduced this change when the modeled ne was scaled up by 2.8x, close to values obtained using the Allen-Baumbach equation. No scaling of B from the model was necessary. A refined fit to the observations was obtained when the observationally based total electron content (TEC) curves were introduced. Changes in LOS TEC were determined from radio frequency shifts as the signal passed to successively lower electron concentrations during egress. A good fit to the observations was achieved with an offset of 7e21 m-2 added. Back-calculating ne along the LOS from the TEC curves, we found that the equivalent ne scaling compared to the model output was higher by a factor of 3. The combination of solar surface magnetogram-based MHD coronal
Non-local thermodynamic equilibrium inversions from a 3D MHD chromospheric model
Rodríguez, Jaime de la Cruz; Carlsson, Mats; Leenaarts, Jorrit
2012-01-01
The structure of the solar chromosphere is believed to be governed by magnetic fields, even in quiet-Sun regions that have a relatively weak photospheric field. During the past decade inversion methods have emerged as powerful tools for analyzing the chromosphere of active regions. The applicability of inversions to infer the stratification of the physical conditions in a dynamic 3D solar chromosphere has not yet been studied in detail. This study aims to establish the diagnostic capabilities of non-local thermodynamical equilibrium (NLTE) inversion techniques of Stokes profiles induced by the Zeeman effect in the Ca II 8542 line. We computed the Ca II atomic level populations in a snapshot from a 3D radiation-MHD simulation of the quiet solar atmosphere in non-LTE using the 3D radiative transfer code Multi3d. These populations were used to compute synthetic full-Stokes profiles in the Ca II 8542 line using 1.5D radiative transfer and the inversion code Nicole. The profiles were then spectrally degraded to ac...
Many-Task Computing Tools for Multiscale Modeling
Katz, Daniel S.; Ripeanu, Matei; Wilde, Michael
2011-01-01
This paper discusses the use of many-task computing tools for multiscale modeling. It defines multiscale modeling and places different examples of it on a coupling spectrum, discusses the Swift parallel scripting language, describes three multiscale modeling applications that could use Swift, and then talks about how the Swift model is being extended to cover more of the multiscale modeling coupling spectrum.
Energy Technology Data Exchange (ETDEWEB)
Nichols, T.T.; Taylor, D.D.
2002-07-18
A status is presented of the development during FY2002 of a database for physical properties models for the simulation of the treatment of Sodium-Bearing Waste (SBW) at the Idaho National Engineering and Environmental Laboratory. An activity coefficient model is needed for concentrated, aqueous, multi-electrolyte solutions that can be used by process design practitioners. Reasonable first-order estimates of activity coefficients in the relevant media are needed rather than an incremental improvement in theoretical approaches which are not usable by practitioners. A comparison of the Electrolyte Non-Random Two-Liquid (ENRTL) and Pitzer ion-interaction models for the thermodynamic representation of SBW is presented. It is concluded that Pitzer's model is superior to ENRTL in modeling treatment processes for SBW. The applicability of the Pitzer treatment to high concentrations of pertinent species and to the determination of solubilities and chemical equilibria is addressed. Alternate values of Pitzer parameters for HCl, H2SO4, and HNO3 are proposed, applicable up to 16m, and 12m, respectively. Partial validation of the implementation of Pitzer's treatment within the commercial process simulator ASPEN Plus was performed.
Energy Technology Data Exchange (ETDEWEB)
Nichols, Todd Travis; Taylor, Dean Dalton
2002-07-01
A status is presented of the development during FY2002 of a database for physical properties models for the simulation of the treatment of Sodium-Bearing Waste (SBW) at the Idaho National Engineering and Environmental Laboratory. An activity coefficient model is needed for concentrated, aqueous, multi-electrolyte solutions that can be used by process design practitioners. Reasonable first-order estimates of activity coefficients in the relevant media are needed rather than an incremental improvement in theoretical approaches which are not usable by practitioners. A comparison of the Electrolyte Non-Random Two-Liquid (ENRTL) and Pitzer ion-interaction models for the thermodynamic representation of SBW is presented. It is concluded that Pitzer's model is superior to ENRTL in modeling treatment processes for SBW. The applicability of the Pitzer treatment to high concentrations of pertinent species and to the determination of solubilities and chemical equilibria is addressed. Alternate values of Pitzer parameters for HCl, H2SO4, and HNO3 are proposed, applicable up to 16m, and 12m, respectively. Partial validation of the implementation of Pitzer's treatment within the commercial process simulator ASPEN Plus was performed.
Confidence interval of intrinsic optimum temperature estimated using thermodynamic SSI model.
Ikemoto, Takaya; Kurahashi, Issei; Shi, Pei-Jian
2013-06-01
The intrinsic optimum temperature for the development of ectotherms is one of the most important factors not only for their physiological processes but also for ecological and evolutional processes. The Sharpe-Schoolfield-Ikemoto (SSI) model succeeded in defining the temperature that can thermodynamically meet the condition that at a particular temperature the probability of an active enzyme reaching its maximum activity is realized. Previously, an algorithm was developed by Ikemoto (Tropical malaria does not mean hot environments. Journal of Medical Entomology, 45, 963-969) to estimate model parameters, but that program was computationally very time consuming. Now, investigators can use the SSI model more easily because a full automatic computer program was designed by Shi et al. (A modified program for estimating the parameters of the SSI model. Environmental Entomology, 40, 462-469). However, the statistical significance of the point estimate of the intrinsic optimum temperature for each ectotherm has not yet been determined. Here, we provided a new method for calculating the confidence interval of the estimated intrinsic optimum temperature by modifying the approximate bootstrap confidence intervals method. For this purpose, it was necessary to develop a new program for a faster estimation of the parameters in the SSI model, which we have also done. © 2012 The Authors Insect Science © 2012 Institute of Zoology, Chinese Academy of Sciences.
Scratch as a computational modelling tool for teaching physics
Lopez, Victor; Hernandez, Maria Isabel
2015-05-01
The Scratch online authoring tool, which features a simple programming language that has been adapted to primary and secondary students, is being used more and more in schools as it offers students and teachers the opportunity to use a tool to build scientific models and evaluate their behaviour, just as can be done with computational modelling programs. In this article, we briefly discuss why Scratch could be a useful tool for computational modelling in the primary or secondary physics classroom, and we present practical examples of how it can be used to build a model.
Shape: A 3D Modeling Tool for Astrophysics.
Steffen, Wolfgang; Koning, Nicholas; Wenger, Stephan; Morisset, Christophe; Magnor, Marcus
2011-04-01
We present a flexible interactive 3D morpho-kinematical modeling application for astrophysics. Compared to other systems, our application reduces the restrictions on the physical assumptions, data type, and amount that is required for a reconstruction of an object's morphology. It is one of the first publicly available tools to apply interactive graphics to astrophysical modeling. The tool allows astrophysicists to provide a priori knowledge about the object by interactively defining 3D structural elements. By direct comparison of model prediction with observational data, model parameters can then be automatically optimized to fit the observation. The tool has already been successfully used in a number of astrophysical research projects.
Systematic Methods and Tools for Computer Aided Modelling
DEFF Research Database (Denmark)
Fedorova, Marina
-friendly system, which will make the model development process easier and faster and provide the way for unified and consistent model documentation. The modeller can use the template for their specific problem or to extend and/or adopt a model. This is based on the idea of model reuse, which emphasizes the use...... and processes can be faster, cheaper and very efficient. The developed modelling framework involves five main elements: 1) a modelling tool, that includes algorithms for model generation; 2) a template library, which provides building blocks for the templates (generic models previously developed); 3) computer...... aided methods and tools, that include procedures to perform model translation, model analysis, model verification/validation, model solution and model documentation; 4) model transfer – export/import to/from other application for further extension and application – several types of formats, such as XML...
Applying Modeling Tools to Ground System Procedures
Di Pasquale, Peter
2012-01-01
As part of a long-term effort to revitalize the Ground Systems (GS) Engineering Section practices, Systems Modeling Language (SysML) and Business Process Model and Notation (BPMN) have been used to model existing GS products and the procedures GS engineers use to produce them.
Directory of Open Access Journals (Sweden)
Cristian F. Costa
2016-06-01
Full Text Available ABSTRACT Jabuticaba is a fruit native of Brazil and, besides containing many nutritional qualities, it also has a good field for use in products such as flour for cakes and biscuits, juice, liqueur, jelly and others. This study aimed to model the drying kinetics and determine the thermodynamic properties of jabuticaba peel at different drying air temperatures. Ripe fruits of jabuticaba (Myrciaria jaboticaba were collected and pulped manually. Drying was carried out in a forced-air circulation oven with a flow of 5.6 m s-1 at temperatures of 40, 50, 60 and 70 °C. Six mathematical models commonly used to represent the drying process of agricultural products were fitted to the experimental data. The Arrhenius model was used to represent the drying constant as a function of temperature. The Midilli model showed the best fit to the experimental data of drying. The drying constant increased with the increment in drying temperature and promoted an activation energy of 37.29 kJ mol-1. Enthalpy and Gibbs free energy decreased with the increase in drying temperature, while entropy decreased and was negative.
Modeling the Jovian subnebula: I - Thermodynamical conditions and migration of proto-satellites
Alibert, Y; Benz, W; Alibert, Yann; Mousis, Olivier; Benz, Willy
2005-01-01
We have developed an evolutionary turbulent model of the Jovian subnebula consistent with the extended core accretion formation models of Jupiter described by Alibert et al. (2005b) and derived from Alibert et al. (2004,2005a). This model takes into account the vertical structure of the subnebula, as well as the evolution of the surface density as given by an $\\alpha$-disk model and is used to calculate the thermodynamical conditions in the subdisk, for different values of the viscosity parameter. We show that the Jovian subnebula evolves in two different phases during its lifetime. In the first phase, the subnebula is fed through its outer edge by the solar nebula as long as it has not been dissipated. In the second phase, the solar nebula has disappeared and the Jovian subdisk expands and gradually clears with time as Jupiter accretes the remaining material. We also demonstrate that early generations of satellites formed during the beginning of the first phase of the subnebula cannot survive in this environ...
Improved thermodynamic modelling of the no-vent fill process and correlation with experimental data
Taylor, W. J.; Chato, D. J.
1991-06-01
The United States plans to establish a permanent manned presence in space and to explore the Solar System have created the need to efficiently handle large quantities of subcritical cryogenic fluids, particularly propellants such as liquid hydrogen and liquid oxygen, in low- to zero-gravity environments. One of the key technologies to be developed for fluid handling is the ability to transfer the cryogens between storage and spacecraft tanks. The no-vent fill method has been identified as one way to perform this transfer. In order to understand how to apply this method, a model of the no-vent fill process is being developed and correlated with experimental data. The verified models then can be used to design and analyze configurations for tankage and subcritical fluid depots. This paper discusses the development of an improved macroscopic thermodynamic model of the no-vent fill process and correlates the analytical results from the computer program implementation of the model with experimental results for two different test tanks at NASA Lewis Research Center.
Destri, C
1994-01-01
We present a unified approach to the Thermodynamic Bethe Ansatz (TBA) for magnetic chains and field theories that includes the finite size (and zero temperature) calculations for lattice BA models. In all cases, the free energy follows by quadratures from the solution of a {\\bf single} non-linear integral equation (NLIE). [A system of NLIE appears for nested BA]. We derive the NLIE for: a) the six-vertex model with twisted boundary conditions; b) the XXZ chain in an external magnetic field h_z and c) the sine-Gordon-massive Thirring model (sG-mT) in a periodic box of size \\b \\equiv 1/T using the light-cone approach. This NLIE is solved by iteration in one regime (high T in the XXZ chain and low T in the sG-mT model). In the opposite (conformal) regime, the leading behaviors are obtained in closed form. Higher corrections can be derived from the Riemann-Hilbert form of the NLIE that we present.
Institute of Scientific and Technical Information of China (English)
CHENG Bin; Timo Vihma; ZHANG Zhan-hai; LI Zhi-jun; WU Hui-ding
2008-01-01
Evolution of the Arctic sea ice and its snow cover during the SHEBA year were simulated by applying a high-resolution thermodynamic snow/ice model (HIGHTSI). Attention was paid to the impact of albedo on snow and sea ice mass balance, effect of snow on total ice mass balance, and the model vertical resolution.The SHEBA annual simulation was made applying the best possible external forcing data set created by the Sea Ice Model Intercomparison Project. The HIGHTSI control run reasonably reproduced the observed snow and ice thickness. A number of albedo schemes were incorporated into HIGHTSI to study the feedhack processes between the albedo and snow and ice thickness. The snow thickness turned out to be an essential variable in the albedo parametetization. Albedo schemes dependent on the surface temperature were liable to excessive positive feedback effects generated by errors in the modelled surface temperature. The superimposed ice formation should be taken into account for the annual Arctic sea ice mass balance.
Reinisch, Guillaume; Leyssale, Jean-Marc; Vignoles, Gérard L.
2010-10-01
We present an extension of some popular hindered rotor (HR) models, namely, the one-dimensional HR (1DHR) and the degenerated two-dimensional HR (d2DHR) models, allowing for a simple and accurate treatment of internal rotations. This extension, based on the use of a variable kinetic function in the Hamiltonian instead of a constant reduced moment of inertia, is extremely suitable in the case of rocking/wagging motions involved in dissociation or atom transfer reactions. The variable kinetic function is first introduced in the framework of a classical 1DHR model. Then, an effective temperature and potential dependent constant is proposed in the cases of quantum 1DHR and classical d2DHR models. These methods are finally applied to the atom transfer reaction SiCl3+BCl3→SiCl4+BCl2. We show, for this particular case, that a proper accounting of internal rotations greatly improves the accuracy of thermodynamic and kinetic predictions. Moreover, our results confirm (i) that using a suitably defined kinetic function appears to be very adapted to such problems; (ii) that the separability assumption of independent rotations seems justified; and (iii) that a quantum mechanical treatment is not a substantial improvement with respect to a classical one.
Development of a Gas Dynamic and Thermodynamic Simulation Model of the Lontra Blade Compressor™
Karlovsky, Jerome
2015-08-01
The Lontra Blade Compressor™ is a patented double acting, internally compressing, positive displacement rotary compressor of innovative design. The Blade Compressor is in production for waste-water treatment, and will soon be launched for a range of applications at higher pressure ratios. In order to aid the design and development process, a thermodynamic and gas dynamic simulation program has been written in house. The software has been successfully used to optimise geometries and running conditions of current designs, and is also being used to evaluate future designs for different applications and markets. The simulation code has three main elements. A positive displacement chamber model, a leakage model and a gas dynamic model to simulate gas flow through ports and to track pressure waves in the inlet and outlet pipes. All three of these models are interlinked in order to track mass and energy flows within the system. A correlation study has been carried out to verify the software. The main correlation markers used were mass flow, chamber pressure, pressure wave tracking in the outlet pipe, and volumetric efficiency. It will be shown that excellent correlation has been achieved between measured and simulated data. Mass flow predictions were to within 2% of measured data, and the timings and magnitudes of all major gas dynamic effects were well replicated. The simulation will be further developed in the near future to help with the optimisation of exhaust and inlet silencers.
A thermodynamic model of the Z-phase Cr(V, Nb)N
DEFF Research Database (Denmark)
Danielsen, Hilmar Kjartansson; Hald, John
2007-01-01
Precipitation of large Z-phase particles, Cr(V, Nb)N, replacing fine MX carbonitrides, Nb(C, N) or V(N, C), has recently been identified as a major cause for premature breakdown in long-term creep strength of a number of new 9%–12% Cr martensitic steels, especially the high Cr variants....... A thermodynamic model of the Z-phase has been developed based on the regular solution model. The model predicts Z-phase to be stable and to fully replace the MX particles in most of the new 9%–12% Cr steels, which is in good agreement with experimental observations. The rate of precipitation of Z......-phase is a crucial factor for the long-term creep stability of these steels. Driving force calculations with the model allow estimates of the influence of the individual alloying elements on the rate of Z-phase precipitation, and can thus contribute useful information for alloy design to delay and retard Z...
Milosevic, M.; Hendriks, I.; Smits, R.E.R.; Schuur, Boelo; de Haan, A.B.
2013-01-01
Liquid–liquid extraction using ethers as solvents is a potentially energy saving alternative for the concentration of aqueous ferric chloride solutions. Adequate thermodynamic models that describe the behavior of the resulting quaternary systems (FeCl3, ether, acid and water) are not available in
DEFF Research Database (Denmark)
Dyekjær, Jane Dannow; Jonsdottir, Svava Osk
2003-01-01
Quantitative Structure-Property Relationship (QSPR) models for prediction of various thermodynamic properties of simple organic compounds have been developed. A number of new descriptors are proposed and used alongside with descriptors available within the Codessa program. An important feature in...
Im, Maesoon; Im, Hwon; Lee, Joo-Hyung; Yoon, Jun-Bo; Choi, Yang-Kyu
2010-11-16
A polydimethylsiloxane (PDMS) elastomer surface with perfectly ordered microstructures having an inverse-trapezoidal cross-sectional profile (simply PDMS trapezoids) showed superhydrophobic and transparent characteristics under visible light as reported in our previous work. The addition of a fluoropolymer (Teflon) coating enhances both features and provides oleophobicity. This paper focuses on the analytical modeling of the fabricated PDMS trapezoids structure and thermodynamic analysis based on the Gibbs free energy analysis. Additionally, the wetting characteristics of the fabricated PDMS trapezoids surface before and after the application of the Teflon coating are analytically explained. The Gibbs free energy analysis reveals that, due to the Teflon coating, the Cassie-Baxter state becomes energetically more favorable than the Wenzel state and the contact angle difference between the Cassie-Baxter state and the Wenzel state decreases. These two findings support the robustness of the superhydrophobicity of the fabricated Teflon-coated PDMS trapezoids. This is then verified via the impinging test of a water droplet at a high speed. The dependencies of the design parameters in the PDMS trapezoids on the hydrophobicity are also comprehensively studied through a thermodynamic analysis. Geometrical dependency on the hydrophobicity shows that overhang microstructures do not have a significant influence on the hydrophobicity. In contrast, the intrinsic contact angle of the structural material is most important in determining the apparent contact angle. On the other hand, the experimental results showed that the side angles of the overhangs are critical not for the hydrophobic but for the oleophobic property with liquids of a low surface tension. Understanding of design parameters in the PDMS trapezoids surface gives more information for implementation of superhydrophobic surfaces.
Novel multiscale modeling tool applied to Pseudomonas aeruginosa biofilm formation.
Biggs, Matthew B; Papin, Jason A
2013-01-01
Multiscale modeling is used to represent biological systems with increasing frequency and success. Multiscale models are often hybrids of different modeling frameworks and programming languages. We present the MATLAB-NetLogo extension (MatNet) as a novel tool for multiscale modeling. We demonstrate the utility of the tool with a multiscale model of Pseudomonas aeruginosa biofilm formation that incorporates both an agent-based model (ABM) and constraint-based metabolic modeling. The hybrid model correctly recapitulates oxygen-limited biofilm metabolic activity and predicts increased growth rate via anaerobic respiration with the addition of nitrate to the growth media. In addition, a genome-wide survey of metabolic mutants and biofilm formation exemplifies the powerful analyses that are enabled by this computational modeling tool.
Novel multiscale modeling tool applied to Pseudomonas aeruginosa biofilm formation.
Directory of Open Access Journals (Sweden)
Matthew B Biggs
Full Text Available Multiscale modeling is used to represent biological systems with increasing frequency and success. Multiscale models are often hybrids of different modeling frameworks and programming languages. We present the MATLAB-NetLogo extension (MatNet as a novel tool for multiscale modeling. We demonstrate the utility of the tool with a multiscale model of Pseudomonas aeruginosa biofilm formation that incorporates both an agent-based model (ABM and constraint-based metabolic modeling. The hybrid model correctly recapitulates oxygen-limited biofilm metabolic activity and predicts increased growth rate via anaerobic respiration with the addition of nitrate to the growth media. In addition, a genome-wide survey of metabolic mutants and biofilm formation exemplifies the powerful analyses that are enabled by this computational modeling tool.
XLISP-Stat Tools for Building Generalised Estimating Equation Models
Directory of Open Access Journals (Sweden)
Thomas Lumley
1996-12-01
Full Text Available This paper describes a set of Lisp-Stat tools for building Generalised Estimating Equation models to analyse longitudinal or clustered measurements. The user interface is based on the built-in regression and generalised linear model prototypes, with the addition of object-based error functions, correlation structures and model formula tools. Residual and deletion diagnostic plots are available on the cluster and observation level and use the dynamic graphics capabilities of Lisp-Stat.
A Components Library System Model and the Support Tool
Institute of Scientific and Technical Information of China (English)
MIAO Huai-kou; LIU Hui; LIU Jing; LI Xiao-bo
2004-01-01
Component-based development needs a well-designed components library and a set of support tools.This paper presents the design and implementation of a components library system model and its support tool UMLCASE.A set of practical CASE tools is constructed.UMLCASE can use UML to design Use Case Diagram, Class Diagram etc.And it integrates with components library system.
Konrad-Schmolke, M.; Schildhauer, H.
2013-12-01
Growth and chemical composition of garnet in metamorphic rocks excellently reflect thermodynamic as well kinetic properties of the host rock during garnet growth. This valuable information can be extracted from preserved compositional growth zoning patterns in garnet. However, metamorphic rocks often contain multiple garnet generations that commonly develop as corona textures with distinct compositional core-overgrowth features. This circumstance can lead to a misinterpretation of information extracted from such grains if the age- and metamorphic relations between different garnet generations are unclear. Especially garnets from high-pressure (HP) and ultra high-pressure (UHP) rocks often preserve textures that show multiple growth stages reflected in core-overgrowth differences both in main and trace element composition and in the inclusion assemblage. Distinct growth zones often have sharp boundaries with strong compositional gradients and/or inclusion- and trace-element-enriched zones. Such growth patterns indicate episodic garnet growth as well as growth interruptions during the garnet evolution. A quantitative understanding of these distinct growth pulses enables the relationship between reaction path, age determinations in spatially controlled garnet domains or temperature-time constraints to be fully characterised. In this study we apply thermodynamic forward models to simulate garnet growth along a series of HP and UHP P-T paths, representative for subducted oceanic crust. We study garnet growth in different basaltic rock compositions and under different element fractionation scenarios in order to detect path-dependent P-T regions of limited or ceased garnet growth. Modeled data along P-T trajectories involving fractional crystallisation are assembled in P-T diagrams reflecting garnet growth in a changing bulk rock composition. Our models show that in all investigated rock compositions garnet growth along most P-T trajectories is discontinuous, pulse
The Deep Crust Magmatic Refinery, Part 1: A Coupled Thermodynamic and Two-phase Flow Model
Riel, N., Jr.; Bouilhol, P.; Van Hunen, J.; Velic, M.; Magni, V.
2016-12-01
Metamorphic and magmatic processes occurring in the deep crust ultimately control the chemical and physical characteristic of the continental crust. A complex interplay between magma intrusion, crystallization, and reaction with the pre-existing crust provide a wide range of differentiated magma and cumulates (and / or restites) that will feed the upper crustal levels with evolved melt while constructing the lower crust. With growing evidence from field and experimental studies, it becomes clearer that crystallization and melting processes are non-exclusive but should be considered together. Incoming H2O bearing mantle melts will start to fractionate to a certain extent, forming cumulates but also releasing heat and H2O to the intruded host-rock allowing it to melt in saturated conditions. The end-result of such dynamic system is a function of the amount and composition of melt input, and extent of reaction with the host which is itself dependent on the migration mode of the melts. To assess the dynamics of this deep magmatic system we developed a new 2-D two-phase flow code using finite volume method. Our formulation takes into account: (i) melt flow through a viscous porous matrix with temperature- and melt-content dependent host-rock viscosity, (ii) heat transfer, assuming local thermal equilibrium between solid and liquid, (iii) thermodynamic modelling of stable phases, (iv) injection of fractionated melt from crystallizing basalt at the Moho and (v) chemical advection of both the solid and liquid compositions. Here we present the core of our modelling approach, especially the petrological implementation. We show in details that our thermodynamic model can reproduce well both the sub- and supra solidus phase relationship and composition of the host-rock. We apply our method to an idealized amphibolite lower crust that is affected by a magmatic event represented by the intrusion of a wet mantle melt into the crust at Moho depth. The models [see Bouilhol et al
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
The relationship between desert evolution and change in albedo has been investigated quasi-analytically using a zonal mean two-dimensional energy balance model which considers the radiation transmission process due to thermodynamics and bound- ary layer movement caused by kinetics. A climate state including temperature, zonal wind, meridional wind and vertical wind can be simulated according to the current zonal distribution of albedo. Given desert distribution, characterized by the value and distribution of albedo, the response of climate on albedo has been studied to analyze the evolution of desert climate. One significant result is that the simple model can reproduce mean meridional circulation. Another result indicates that climate corresponds to two equilibria. This happens when the junction temperature between vegetation and desert is higher than a certain critical value. As for the first equilibrium, the desert belt is predicted to move southward in the northern hemisphere with the increasing values of albedo, which corresponds to the current trend of climate change. For the second equilibrium, vegetation will expand northward with increasing values of albedo, which would indicate a narrowing of the desert belt. In order to determine if the two equilibria exist, new physical models are needed.
Comparison of two models of a double inlet miniature pulse tube refrigerator: Part A thermodynamics
Nika, Philippe; Bailly, Yannick
2002-10-01
The cooling of electronic components is of great interest to improve their capabilities, especially for CMOS components or infrared sensors. The purpose of this paper is to present the design and the optimization of a miniature double inlet pulse tube refrigerator (DIPTR) dedicated to such applications. Special precautions have to be considered in modeling the global functioning of small scale DIPTR systems and also in estimating the net cooling power. In fact, thermal gradients are greater than those observed in normal scale systems, and moreover, because of the small dimensions of ducts (diameter), the pulse tube cannot be assumed to be adiabatic. Hence thermal heat conduction phenomena must be considered. Besides dead volumes introduced by junctions and capillaries cannot be neglected any more in front of the volume of the gas tube itself. The hydrodynamic and thermal behaviors of the cooler are predicted by means of two different approaches: a classical thermodynamic model and a model based on an electrical analogy. The results of these analysis are tested and criticized by comparing them with experimental data obtained on a small commercial pulse tube refrigerator.
A thermodynamic and kinetic model for paste–aggregate interactions and the alkali–silica reaction
Energy Technology Data Exchange (ETDEWEB)
Guthrie, George D., E-mail: geo@lanl.gov; Carey, J. William
2015-10-15
A new conceptual model is developed for ASR formation based on geochemical principles tied to aqueous speciation, silica solubility, kinetically controlled mineral dissolution, and diffusion. ASR development is driven largely by pH and silica gradients that establish geochemical microenvironments between paste and aggregate, with gradients the strongest within the aggregate adjacent to the paste boundary (i.e., where ASR initially forms). Super-saturation of magadiite and okenite (crystalline ASR surrogates) occurs in the zone defined by gradients in pH, dissolved silica, Na{sup +}, and Ca{sup 2} {sup +}. This model provides a thermodynamic rather than kinetic explanation of why quartz generally behaves differently from amorphous silica: quartz solubility does not produce sufficiently high concentrations of H{sub 4}SiO{sub 4} to super-saturate magadiite, whereas amorphous silica does. The model also explains why pozzolans do not generate ASR: their fine-grained character precludes formation of chemical gradients. Finally, these gradients have interesting implications beyond the development of ASR, creating unique biogeochemical environments.
Spectral and thermodynamic properties of the Sachdev-Ye-Kitaev model
García-García, Antonio M.; Verbaarschot, Jacobus J. M.
2016-12-01
We study spectral and thermodynamic properties of the Sachdev-Ye-Kitaev model, a variant of the k -body embedded random ensembles studied for several decades in the context of nuclear physics and quantum chaos. We show analytically that the fourth- and sixth-order energy cumulants vanish in the limit of a large number of particles N →∞ , which is consistent with a Gaussian spectral density. However, for finite N , the tail of the average spectral density is well approximated by a semicircle law. The specific heat coefficient, determined numerically from the low-temperature behavior of the partition function, is consistent with the value obtained by previous analytical calculations. For energy scales of the order of the mean level spacing we show that level statistics are well described by random matrix theory. Due to the underlying Clifford algebra of the model, the universality class of the spectral correlations depends on N . For larger energy separations we identify an energy scale that grows with N , reminiscent of the Thouless energy in mesoscopic physics, where deviations from random matrix theory are observed. Our results are a further confirmation that the Sachdev-Ye-Kitaev model is quantum chaotic for all time scales. According to recent claims in the literature, this is an expected feature in field theories with a gravity dual.
Thermodynamic modeling of liquid–liquid phase change solvents for CO_{2} capture
DEFF Research Database (Denmark)
Waseem Arshad, Muhammad; von Solms, Nicolas; Thomsen, Kaj
2016-01-01
A thermodynamic model based on Extended UNIQUAC framework has been developed in this work for the de-mixing liquid–liquid phase change solvents, DEEA (2-(diethylamino)ethanol) and MAPA (3-(methylamino)propylamine). Parameter estimation was performed for two ternary systems, H2O-DEEA-CO2 and H2O-MAPA......-CO2, and a quaternary system, H2O-DEEA-MAPA-CO2 (phase change system), by using different types of experimental data (equilibrium and thermal) consisting of pure amine vapor pressure, vapor-liquid equilibrium, solid-liquid equilibrium, liquid–liquid equilibrium, excess enthalpy, and heat of absorption...... are valid in the temperature range from −25 to 200 °C, CO2 partial pressure from 0 to 945 kPa, and concentration of DEEA, MAPA, and CO2 up to 131, 23, and 33 mol(kg H2O)−1, respectively. The model calculated speciation are also presented for the studied systems. The model developed in this work can be used...
Mirani, Mohammad Reza; Rahimpour, Farshad
2015-11-27
Hydrophobic interaction chromatography (HIC) is a useful method for isolation and purification of macromolecules. HIC separates proteins on the basis of surface hydrophobicity while generally retaining the activity of proteins. Aqueous mobile phases with high salt concentrations are often used to adsorb the proteins on a mildly hydrophobic support. In this research, the thermodynamic model of Chen and Sun, which predicts the adsorption isotherms of protein in presence of different type of salts, was modified by substitution the protein and salt activities in the mobile phase instead of their concentrations. In addition, model was examined for studying the adsorption of BSA, HSA, α-lactalbumin and Trypsinogen on different sepharose gels. The model parameters of Chen and Sun are adsorption equilibrium constant (KP), protein dehydration equilibrium constant (Ks), salt coefficient (α) and number of ligand binding (n). By substitution activity instead of salt and protein concentration, two other parameters (c1 and As), which related to the activity coefficients, are added to the model. The parameters of this nonlinear model are calculated by genetic algorithm (GA). The maximum average absolute percentage deviation (AAD) for the data which are obtained from the adsorption isotherm of BSA on phenyl sepharose gel, in the presence of different concentration of NaCl was 4.8%, while for Chen and Sun model, was 22.0%. Also maximum ADD for HSA, α-lactalbumin, and Trypsinogen adsorption was 7.8, 6.9, and 8.4, respectively. The results indicate that the modified model has adequate accuracy to predict protein HIC behaviour.
Thermodynamically Consistent Algorithms for the Solution of Phase-Field Models
Vignal, Philippe
2016-02-11
Phase-field models are emerging as a promising strategy to simulate interfacial phenomena. Rather than tracking interfaces explicitly as done in sharp interface descriptions, these models use a diffuse order parameter to monitor interfaces implicitly. This implicit description, as well as solid physical and mathematical footings, allow phase-field models to overcome problems found by predecessors. Nonetheless, the method has significant drawbacks. The phase-field framework relies on the solution of high-order, nonlinear partial differential equations. Solving these equations entails a considerable computational cost, so finding efficient strategies to handle them is important. Also, standard discretization strategies can many times lead to incorrect solutions. This happens because, for numerical solutions to phase-field equations to be valid, physical conditions such as mass conservation and free energy monotonicity need to be guaranteed. In this work, we focus on the development of thermodynamically consistent algorithms for time integration of phase-field models. The first part of this thesis focuses on an energy-stable numerical strategy developed for the phase-field crystal equation. This model was put forward to model microstructure evolution. The algorithm developed conserves, guarantees energy stability and is second order accurate in time. The second part of the thesis presents two numerical schemes that generalize literature regarding energy-stable methods for conserved and non-conserved phase-field models. The time discretization strategies can conserve mass if needed, are energy-stable, and second order accurate in time. We also develop an adaptive time-stepping strategy, which can be applied to any second-order accurate scheme. This time-adaptive strategy relies on a backward approximation to give an accurate error estimator. The spatial discretization, in both parts, relies on a mixed finite element formulation and isogeometric analysis. The codes are
Energy Technology Data Exchange (ETDEWEB)
Aguilar, C., E-mail: claudio.aguilar@usm.cl [Departamento de Ingenieria Metalurgica y de Materiales, Universidad Tecnica Federico Santa Maria, Avenida Espana 1680, Valparaiso (Chile); Guzman, D. [Departamento de Metalurgia, Facultad de Ingenieria, Universidad de Atacama, Av. Copayapu 485, Copiapo (Chile); Rojas, P.A. [Escuela de Ingenieria Mecanica, Facultad de Ingenieria, Pontificia Universidad Catolica de Valparaiso, Av. Los Carrera 01567, Quilpue (Chile); Ordonez, Stella [Departamento de Ingenieria Metalurgica, Facultad de Ingenieria, Universidad de Santiago de Chile, Av. L. Bernardo O' Higgins 3363, Santiago (Chile); Rios, R. [Instituto de Materiales y Procesos Termomecanicos, Facultad de Ciencias de la Ingenieria, Universidad Austral de Chile, General Lagos 2086, Valdivia (Chile)
2011-08-15
Highlights: {yields} Extension of solid solution in Cu-Mo systems achieved by mechanical alloying. {yields} Simple thermodynamic model to explain extension of solid solution of Mo in Cu. {yields} Model gives results that are consistent with the solubility limit extension reported in other works. - Abstract: The objective of this work is proposing a simple thermodynamic model to explain the increase in the solubility limit of the powders of the Cu-Mo systems or other binary systems processed by mechanical alloying. In the regular solution model, the effects of crystalline defects, such as; dislocations and grain boundary produced during milling were introduced. The model gives results that are consistent with the solubility limit extension reported in other works for the Cu-Cr, Cu-Nb and Cu-Fe systems processed by mechanical alloying.
Advanced REACH tool: A Bayesian model for occupational exposure assessment
McNally, K.; Warren, N.; Fransman, W.; Entink, R.K.; Schinkel, J.; Van Tongeren, M.; Cherrie, J.W.; Kromhout, H.; Schneider, T.; Tielemans, E.
2014-01-01
This paper describes a Bayesian model for the assessment of inhalation exposures in an occupational setting; the methodology underpins a freely available web-based application for exposure assessment, the Advanced REACH Tool (ART). The ART is a higher tier exposure tool that combines disparate sourc
Techniques and tools for efficiently modeling multiprocessor systems
Carpenter, T.; Yalamanchili, S.
1990-01-01
System-level tools and methodologies associated with an integrated approach to the development of multiprocessor systems are examined. Tools for capturing initial program structure, automated program partitioning, automated resource allocation, and high-level modeling of the combined application and resource are discussed. The primary language focus of the current implementation is Ada, although the techniques should be appropriate for other programming paradigms.
Scratch as a Computational Modelling Tool for Teaching Physics
Lopez, Victor; Hernandez, Maria Isabel
2015-01-01
The Scratch online authoring tool, which features a simple programming language that has been adapted to primary and secondary students, is being used more and more in schools as it offers students and teachers the opportunity to use a tool to build scientific models and evaluate their behaviour, just as can be done with computational modelling…
Scratch as a Computational Modelling Tool for Teaching Physics
Lopez, Victor; Hernandez, Maria Isabel
2015-01-01
The Scratch online authoring tool, which features a simple programming language that has been adapted to primary and secondary students, is being used more and more in schools as it offers students and teachers the opportunity to use a tool to build scientific models and evaluate their behaviour, just as can be done with computational modelling…
Aligning building information model tools and construction management methods
Hartmann, Timo; van Meerveld, H.J.; Vossebeld, N.; Adriaanse, Adriaan Maria
2012-01-01
Few empirical studies exist that can explain how different Building Information Model (BIM) based tool implementation strategies work in practical contexts. To help overcoming this gap, this paper describes the implementation of two BIM based tools, the first, to support the activities at an estimat
Model atmospheres - Tool for identifying interstellar features
Frisch, P. C.; Slojkowski, S. E.; Rodriguez-Bell, T.; York, D.
1993-01-01
Model atmosphere parameters are derived for 14 early A stars with rotation velocities, from optical spectra, in excess of 80 km/s. The models are compared with IUE observations of the stars in regions where interstellar lines are expected. In general, with the assumption of solar abundances, excellent fits are obtained in regions longward of 2580 A, and accurate interstellar equivalent widths can be derived using models to establish the continuum. The fits are poorer at shorter wavelengths, particularly at 2026-2062 A, where the stellar model parameters seem inadequate. Features indicating mass flows are evident in stars with known infrared excesses. In gamma TrA, variability in the Mg II lines is seen over the 5-year interval of these data, and also over timescales as short as 26 days. The present technique should be useful in systematic studies of episodic mass flows in A stars and for stellar abundance studies, as well as interstellar features.
Ghiorso, Mark S.
2010-05-01
Research over the past thirty years has established that thermodynamic modeling is extremely useful for illuminating the production, transport, chemical differentiation, and eruptive potential of magmas. The key to successful modeling of this kind is the formulation of an internally consistent thermodynamic database that includes properties of liquid and solid endmember components, and - most importantly - a cohesive set of models that describe the thermodynamics of mixing of both liquid (± fluid) and mineral solid solutions. Despite numerous successes in the application of thermodynamic modeling to liquid-solid phase equilibria under crustal and upper mantle pressure-temperature conditions, there are critical and relevant areas of application where the models fail to generate useful results. Importantly, these applications include phase equilibria in hornblende- and biotite-bearing magmas and the melting relations of silicate mantle-like bulk compositions at pressures above 3 GPa. Research is underway to address many of these modeling deficiencies. Approaches include (1) the development of new solution models for igneous pyroxenes and garnets, including majoritic garnet components, (2) the reformulation of thermodynamic models for liquid solution properties in order to implement non-deal associative solutions and a more robust equation of state that allows extrapolation of liquid density and free energy to high-pressures, (3) the creation of an experimental program to generate data necessary for the calibration of solution theory for igneous hornblendes and mica, and (4) the use of molecular dynamics simulations to facilitate the creation of a data base of liquid thermochemical properties at high-pressures that will serve as a basis for the calibration of phase equilibria models under Earth-like lower mantle conditions. All of these approaches give hope that in the future it will be possible to compute melting and melt-rock reaction over a much broader range of
Lee, Yi Feng; Graalfs, Heiner; Frech, Christian
2016-09-16
An extended model is developed to describe protein retention in mixed-mode chromatography based on thermodynamic principles. Special features are the incorporation of pH dependence of the ionic interaction on a mixed-mode resin and the addition of a water term into the model which enables one to describe the total number of water molecules released at the hydrophobic interfaces upon protein-ligand binding. Examples are presented on how to determine the model parameters using isocratic elution chromatography. Four mixed-mode anion-exchanger prototype resins with different surface chemistries and ligand densities were tested using isocratic elution of two monoclonal antibodies at different pH values (7-10) and encompassed a wide range of NaCl concentrations (0-5M). U-shape mixed-mode retention curves were observed for all four resins. By taking into account of the deprotonation and protonation of the weak cationic functional groups in these mixed-mode anion-exchanger prototype resins, conditions which favor protein-ligand binding via mixed-mode strong cationic ligands as well as conditions which favor protein-ligand binding via both mixed-mode strong cationic ligands and non-hydrophobic weak cationic ligands were identified. The changes in the retention curves with pH, salt, protein, and ligand can be described very well by the extended model using meaningful thermodynamic parameters like Gibbs energy, number of ionic and hydrophobic interactions, total number of released water molecules as well as modulator interaction constant. Furthermore, the fitted model parameters based on isocratic elution data can also be used to predict protein retention in dual salt-pH gradient elution chromatography. Copyright © 2016 Elsevier B.V. All rights reserved.
Directory of Open Access Journals (Sweden)
Fei LENG
2008-09-01
Full Text Available This paper discusses the seismic analysis of concrete dams with consideration of material nonlinearity. Based on a consistent rate-dependent model and two thermodynamics-based models, two thermodynamics-based rate-dependent constitutive models were developed with consideration of the influence of the strain rate. They can describe the dynamic behavior of concrete and be applied to nonlinear seismic analysis of concrete dams taking into account the rate sensitivity of concrete. With the two models, a nonlinear analysis of the seismic response of the Koyna Gravity Dam and the Dagangshan Arch Dam was conducted. The results were compared with those of a linear elastic model and two rate-independent thermodynamics-based constitutive models, and the influences of constitutive models and strain rate on the seismic response of concrete dams were discussed. It can be concluded from the analysis that, during seismic response, the tensile stress is the control stress in the design and seismic safety evaluation of concrete dams. In different models, the plastic strain and plastic strain rate of concrete dams show a similar distribution. When the influence of the strain rate is considered, the maximum plastic strain and plastic strain rate decrease.