Fundamentals of Cryobiology Physical Phenomena and Mathematical Models
Zhmakin, Alexander I
2009-01-01
The book gives a summary of the state-of-the-art of cryobiology and its applications. The accent is on the underlying physical phenomena, which are common in such opposite applications as cryosurgery and cryoconservation, and the corresponding mathematical models, including numerical ones. The treatment of some more special issues is moved to the appendices. The glossary contains definitions and explanations of the major entities. All the topics considered are well referenced. The book is useful to both biologists and physicits of different level including practioners and graduate students.
Modelling transport phenomena in a multi-physics context
Marra, Francesco
2015-01-01
Innovative heating research on cooking, pasteurization/sterilization, defrosting, thawing and drying, often focuses on areas which include the assessment of processing time, evaluation of heating uniformity, studying the impact on quality attributes of the final product as well as considering the energy efficiency of these heating processes. During the last twenty years, so-called electro-heating-processes (radio-frequency - RF, microwaves - MW and ohmic - OH) gained a wide interest in industrial food processing and many applications using the above mentioned technologies have been developed with the aim of reducing processing time, improving process efficiency and, in many cases, the heating uniformity. In the area of innovative heating, electro-heating accounts for a considerable portion of both the scientific literature and commercial applications, which can be subdivided into either direct electro-heating (as in the case of OH heating) where electrical current is applied directly to the food or indirect electro-heating (e.g. MW and RF heating) where the electrical energy is firstly converted to electromagnetic radiation which subsequently generates heat within a product. New software packages, which make easier solution of PDEs based mathematical models, and new computers, capable of larger RAM and more efficient CPU performances, allowed an increasing interest about modelling transport phenomena in systems and processes - as the ones encountered in food processing - that can be complex in terms of geometry, composition, boundary conditions but also - as in the case of electro-heating assisted applications - in terms of interaction with other physical phenomena such as displacement of electric or magnetic field. This paper deals with the description of approaches used in modelling transport phenomena in a multi-physics context such as RF, MW and OH assisted heating.
Modelling transport phenomena in a multi-physics context
Energy Technology Data Exchange (ETDEWEB)
Marra, Francesco [Dipartimento di Ingegneria Chimica e Alimentare - Università degli studi di Salerno Via Ponte Don Melillo - 84084 Fisciano SA (Italy)
2015-01-22
Innovative heating research on cooking, pasteurization/sterilization, defrosting, thawing and drying, often focuses on areas which include the assessment of processing time, evaluation of heating uniformity, studying the impact on quality attributes of the final product as well as considering the energy efficiency of these heating processes. During the last twenty years, so-called electro-heating-processes (radio-frequency - RF, microwaves - MW and ohmic - OH) gained a wide interest in industrial food processing and many applications using the above mentioned technologies have been developed with the aim of reducing processing time, improving process efficiency and, in many cases, the heating uniformity. In the area of innovative heating, electro-heating accounts for a considerable portion of both the scientific literature and commercial applications, which can be subdivided into either direct electro-heating (as in the case of OH heating) where electrical current is applied directly to the food or indirect electro-heating (e.g. MW and RF heating) where the electrical energy is firstly converted to electromagnetic radiation which subsequently generates heat within a product. New software packages, which make easier solution of PDEs based mathematical models, and new computers, capable of larger RAM and more efficient CPU performances, allowed an increasing interest about modelling transport phenomena in systems and processes - as the ones encountered in food processing - that can be complex in terms of geometry, composition, boundary conditions but also - as in the case of electro-heating assisted applications - in terms of interaction with other physical phenomena such as displacement of electric or magnetic field. This paper deals with the description of approaches used in modelling transport phenomena in a multi-physics context such as RF, MW and OH assisted heating.
Modelling transport phenomena in a multi-physics context
International Nuclear Information System (INIS)
Marra, Francesco
2015-01-01
Innovative heating research on cooking, pasteurization/sterilization, defrosting, thawing and drying, often focuses on areas which include the assessment of processing time, evaluation of heating uniformity, studying the impact on quality attributes of the final product as well as considering the energy efficiency of these heating processes. During the last twenty years, so-called electro-heating-processes (radio-frequency - RF, microwaves - MW and ohmic - OH) gained a wide interest in industrial food processing and many applications using the above mentioned technologies have been developed with the aim of reducing processing time, improving process efficiency and, in many cases, the heating uniformity. In the area of innovative heating, electro-heating accounts for a considerable portion of both the scientific literature and commercial applications, which can be subdivided into either direct electro-heating (as in the case of OH heating) where electrical current is applied directly to the food or indirect electro-heating (e.g. MW and RF heating) where the electrical energy is firstly converted to electromagnetic radiation which subsequently generates heat within a product. New software packages, which make easier solution of PDEs based mathematical models, and new computers, capable of larger RAM and more efficient CPU performances, allowed an increasing interest about modelling transport phenomena in systems and processes - as the ones encountered in food processing - that can be complex in terms of geometry, composition, boundary conditions but also - as in the case of electro-heating assisted applications - in terms of interaction with other physical phenomena such as displacement of electric or magnetic field. This paper deals with the description of approaches used in modelling transport phenomena in a multi-physics context such as RF, MW and OH assisted heating
On Process Modelling Using Physical Oriented And Phenomena Based Principles
Directory of Open Access Journals (Sweden)
Mihai Culea
2000-12-01
Full Text Available This work presents a modelling framework based on phenomena description of the process. The approach is taken to easy understand and construct process model in heterogeneous possible distributed modelling and simulation environments. A simplified case study of a heat exchanger is considered and Modelica modelling language to check the proposed concept. The partial results are promising and the research effort will be extended in a computer aided modelling environment based on phenomena.
Constructive Models of Discrete and Continuous Physical Phenomena
2014-02-08
time. The hardware description language VHDL has a related model of time, where time is a member of N×N, and the second value is used in a manner...behaviors. Tech. Rep. RR 95–52, rev. RR (96–56), I3S, April 1996. 4. ARMSTRONG, J. R., AND GRAY, F. G. VHDL Design Representation and Synthesis, sec- ond
Mathematical and physical modeling of thermal stratification phenomena in steel ladles
Putan, V.; Vilceanu, L.; Socalici, A.; Putan, A.
2018-01-01
By means of CFD numerical modeling, a systematic analysis of the similarity between steel ladles and hot-water model regarding natural convection phenomena was studied. The key similarity criteria we found to be dependent on the dimensionless numbers Fr and βΔT. These similarity criteria suggested that hot-water models with scale in the range between 1/5 and 1/3 and using hot water with temperature of 45 °C or higher are appropriate for simulating natural convection in steel ladles. With this physical model, thermal stratification phenomena due to natural convection in steel ladles were investigated. By controlling the cooling intensity of water model to correspond to the heat loss rate of steel ladles, which is governed by Fr and βΔT, the temperature profiles measured in the water bath of the model were to deduce the extent of thermal stratification in liquid steel bath in the ladles. Comparisons between mathematically simulated temperature profiles in the prototype steel ladles and those physically simulated by scaling-up the measured temperatures profiles in the water model showed good agreement. This proved that it is feasible to use a 1/5 scale water model with 45 °C hot water to simulate natural convection in steel ladles. Therefore, besides mathematical CFD models, the physical hot-water model provided an additional means of studying fluid flow and heat transfer in steel ladles.
Costa, Antonio
2016-04-01
Volcanic hazards may have destructive effects on economy, transport, and natural environments at both local and regional scale. Hazardous phenomena include pyroclastic density currents, tephra fall, gas emissions, lava flows, debris flows and avalanches, and lahars. Volcanic hazards assessment is based on available information to characterize potential volcanic sources in the region of interest and to determine whether specific volcanic phenomena might reach a given site. Volcanic hazards assessment is focussed on estimating the distances that volcanic phenomena could travel from potential sources and their intensity at the considered site. Epistemic and aleatory uncertainties strongly affect the resulting hazards assessment. Within the context of critical infrastructures, volcanic eruptions are rare natural events that can create severe hazards. In addition to being rare events, evidence of many past volcanic eruptions is poorly preserved in the geologic record. The models used for describing the impact of volcanic phenomena generally represent a range of model complexities, from simplified physics based conceptual models to highly coupled thermo fluid dynamical approaches. Modelling approaches represent a hierarchy of complexity, which reflects increasing requirements for well characterized data in order to produce a broader range of output information. In selecting models for the hazard analysis related to a specific phenomenon, questions that need to be answered by the models must be carefully considered. Independently of the model, the final hazards assessment strongly depends on input derived from detailed volcanological investigations, such as mapping and stratigraphic correlations. For each phenomenon, an overview of currently available approaches for the evaluation of future hazards will be presented with the aim to provide a foundation for future work in developing an international consensus on volcanic hazards assessment methods.
Redfors, Andreas; Ryder, Jim
2001-01-01
Examines third year university physics students' use of models when explaining familiar phenomena involving interaction between metals and electromagnetic radiation. Concludes that few students use a single model consistently. (Contains 27 references.) (DDR)
Modelling of Transport Phenomena
K., Itoh; S.-I., Itoh; A., Fukuyama
1993-01-01
In this review article, we discuss key features of the transport phenomena and theoretical modelling to understand them. Experimental observations have revealed the nature of anomalous transport, i.e., the enhancement of the transport coefficients by the gradients of the plasma profiles, the pinch phenomena, the radial profile of the apomalous transport coefficients, the variation of the transport among the Bohm diffusion, Pseudo-classical confinement, L-mode and variety of improved confineme...
International Nuclear Information System (INIS)
McCauley, E.W.; Holman, G.S.; Aust, E.; Schwan, H.; Vollbrandt, J.
1980-01-01
Using the results of large scale multivent tests conducted by GKSS, a physical model of chugging is developed. The unique combination of accurate digital data and cinematic data has provided the derivation of a detailed, quantified correlation between the dynamic physical variables and the associated two-phase thermo-hydraulic phenomena occurring during lean suppression (chugging) phases of the loss-of-coolant accident in a boiling water reactor pressure suppression system
International Nuclear Information System (INIS)
Benjamin, A.S.; Paez, T.L.; Brown, N.N.
1998-01-01
In most probabilistic risk assessments, there is a subset of accident scenarios that involves physical challenges to the system, such as high heat rates and/or accelerations. The system's responses to these challenges may be complicated, and their prediction may require the use of long-running computer codes. To deal with the many scenarios demanded by a risk assessment, the authors have been investigating the use of artificial neural networks (ANNs) as a fast-running estimation tool. They have developed a multivariate linear spline algorithm by extending previous ANN methods that use radial basis functions. They have applied the algorithm to problems involving fires, shocks, and vibrations. They have found that within the parameter range for which it is trained, the algorithm can simulate the nonlinear responses of complex systems with high accuracy. Running times per case are less than one second
A Mind/Brain/Matter Model Consistent with Quantum Physics and UFO phenomena
1979-01-01
realities of a second type (E.P. Wigr, ,.’ "Two Kinds of Reality," The Monist , Vol. 48, No. 2, April 1964). Note that the modei -eing c dvanced by the...biological organism, including egos of "dead" biosystems. Note also that the wave-packet reduction (collapse of the wave function) is not a relativistically ...new fourth law of logic, which is briefly described and summarized. A new photon interaction model. of quantized observable changc is also presented
New phenomena in neutrino physics
International Nuclear Information System (INIS)
Kopp, Joachim
2009-01-01
In this thesis, we discuss two new concepts in neutrino physics: The neutrino Moessbauer effect and non-standard neutrino interactions. We show that neutrinos emitted and absorbed in recoil-free processes (Moessbauer neutrinos) can oscillate in spite of their near monochromaticity. We support this statement by quantum mechanical wave packet arguments and by a quantum field theoretical (QFT) calculation of the combined rate of Moessbauer neutrino emission, propagation and absorption. The QFT approach does not require any a priori assumptions on the neutrino wave function, and it allows us to include a realistic treatment of the different mechanisms leading to broadening of the emission and absorption lines. In the second part of this work, we study the phenomenology of non-standard neutrino interactions (NSI). We classifying the allowed NSI operators according to their impact on future oscillation experiments and present numerical results for the NSI sensitivities of reactor, superbeam and neutrino factory experiments. We point out that NSI could mimic standard oscillation effects, and might therefore lead to incorrect fit values for the oscillation parameters. For the case of the neutrino factory, we perform a detailed optimisation study to determine the optimum muon energy and detector configuration. (orig.)
New phenomena in neutrino physics
Energy Technology Data Exchange (ETDEWEB)
Kopp, Joachim
2009-04-15
In this thesis, we discuss two new concepts in neutrino physics: The neutrino Moessbauer effect and non-standard neutrino interactions. We show that neutrinos emitted and absorbed in recoil-free processes (Moessbauer neutrinos) can oscillate in spite of their near monochromaticity. We support this statement by quantum mechanical wave packet arguments and by a quantum field theoretical (QFT) calculation of the combined rate of Moessbauer neutrino emission, propagation and absorption. The QFT approach does not require any a priori assumptions on the neutrino wave function, and it allows us to include a realistic treatment of the different mechanisms leading to broadening of the emission and absorption lines. In the second part of this work, we study the phenomenology of non-standard neutrino interactions (NSI). We classifying the allowed NSI operators according to their impact on future oscillation experiments and present numerical results for the NSI sensitivities of reactor, superbeam and neutrino factory experiments. We point out that NSI could mimic standard oscillation effects, and might therefore lead to incorrect fit values for the oscillation parameters. For the case of the neutrino factory, we perform a detailed optimisation study to determine the optimum muon energy and detector configuration. (orig.)
Modelling of condensation phenomena
International Nuclear Information System (INIS)
Jeong, Jae Jun; Chang, Won Pyo
1996-07-01
Condensation occurs when vapor is cooled sufficiently below the saturation temperature to induce the nucleation of droplets. Such nucleation may occur homogeneously within the vapor or heterogeneously on entrained particular matter. Heterogeneous nucleation may occur on the walls of the system, where the temperature is below the saturation temperature. There are two forms of heterogeneous condensation, drop-wise and film-wise. Another form of condensation occurs when vapor directly contacts to subcooled liquid. In nuclear power plant systems, all forms of condensation may occur during normal operation or accident conditions. In this work the modelling of condensation is surveyed, including the Nusselts' laminar film condensation theory in 1916, Rohsenow's turbulent film condensation model in 1950s, and Chen's models in 1987. Major attention is paid on the film condensation models among various research results because of its importance in engineering applications. It is found that theory, experiment, and empirical correlations for film condensation are well established, but research for drop-wise and direct-contact condensation are not sufficient yet. Condensation models in the best-estimate system codes such as RELAP5/MOD3 and CATHARE2 are also investigated. 3 tabs., 11 figs., 36 refs. (Author)
Self-organization phenomena in plasma physics
International Nuclear Information System (INIS)
Sanduloviciu, M.; Popescu, S.
2001-01-01
The self-assembling in nature and laboratory of structures in systems away from thermodynamic equilibrium is one of the problems that mostly fascinates the scientists working in all branches of science. In this context a substantial progress has been obtained by investigating the appearance of spatial and spatiotemporal patterns in plasma. These experiments revealed the presence of a scenario of self-organization able to suggest an answer to the central problem of the 'Science of Complexity', why matter transits spontaneously from a disordered into an ordered state? Based on this scenario of self-organization we present arguments proving the possibility to explain the challenging problems of nonequilibrium physics in general. These problems refer to: (i) genuine origin of phase transitions observed in gaseous conductors and semiconductors; (ii) the elucidation of the role played by self-organization in the simulation of oscillations; (iii) the physical basis of anomalous transport of matter and energy with special reference to the possibilities of improving the economical performance of fusion devices; (iv) the possibility to use self-confined gaseous space charged configurations as an alternative to the magnetically confined plasma used at present in fusion devices. In other branches of sciences, as for instance in Biology, the self-organization scenario reveals a new insight into a mechanism able to explain the appearance of the simplest possible space charge configuration able to evolve, under suitable conditions, into prebiotic structures. Referring to phenomena observed in nature, the same self-organization scenario suggests plausible answers to the appearance of ball lightening but also to the origin of the flickering phenomena observed in the light emission of the Sun and stars. For theory the described self-organization scenario offers a new physical basis for many problems of nonlinear science not solved yet and also a new model for the so-called 'self
Mathematical Modeling of Diverse Phenomena
Howard, J. C.
1979-01-01
Tensor calculus is applied to the formulation of mathematical models of diverse phenomena. Aeronautics, fluid dynamics, and cosmology are among the areas of application. The feasibility of combining tensor methods and computer capability to formulate problems is demonstrated. The techniques described are an attempt to simplify the formulation of mathematical models by reducing the modeling process to a series of routine operations, which can be performed either manually or by computer.
Advances in modelling of condensation phenomena
Energy Technology Data Exchange (ETDEWEB)
Liu, W.S.; Zaltsgendler, E. [Ontario Hydro Nuclear, Toronto (Canada); Hanna, B. [Atomic Energy of Canada Limited, Pinawa, Manitoba (Canada)
1997-07-01
The physical parameters in the modelling of condensation phenomena in the CANDU reactor system codes are discussed. The experimental programs used for thermal-hydraulic code validation in the Canadian nuclear industry are briefly described. The modelling of vapour generation and in particular condensation plays a key role in modelling of postulated reactor transients. The condensation models adopted in the current state-of-the-art two-fluid CANDU reactor thermal-hydraulic system codes (CATHENA and TUF) are described. As examples of the modelling challenges faced, the simulation of a cold water injection experiment by CATHENA and the simulation of a condensation induced water hammer experiment by TUF are described.
PREFACE: Physics and Mathematics of Nonlinear Phenomena 2013 (PMNP2013)
Konopelchenko, B. G.; Landolfi, G.; Martina, L.; Vitolo, R.
2014-03-01
Modern theory of nonlinear integrable equations is nowdays an important and effective tool of study for numerous nonlinear phenomena in various branches of physics from hydrodynamics and optics to quantum filed theory and gravity. It includes the study of nonlinear partial differential and discrete equations, regular and singular behaviour of their solutions, Hamitonian and bi- Hamitonian structures, their symmetries, associated deformations of algebraic and geometrical structures with applications to various models in physics and mathematics. The PMNP 2013 conference focused on recent advances and developments in Continuous and discrete, classical and quantum integrable systems Hamiltonian, critical and geometric structures of nonlinear integrable equations Integrable systems in quantum field theory and matrix models Models of nonlinear phenomena in physics Applications of nonlinear integrable systems in physics The Scientific Committee of the conference was formed by Francesco Calogero (University of Rome `La Sapienza', Italy) Boris A Dubrovin (SISSA, Italy) Yuji Kodama (Ohio State University, USA) Franco Magri (University of Milan `Bicocca', Italy) Vladimir E Zakharov (University of Arizona, USA, and Landau Institute for Theoretical Physics, Russia) The Organizing Committee: Boris G Konopelchenko, Giulio Landolfi, Luigi Martina, Department of Mathematics and Physics `E De Giorgi' and the Istituto Nazionale di Fisica Nucleare, and Raffaele Vitolo, Department of Mathematics and Physics `E De Giorgi'. A list of sponsors, speakers, talks, participants and the conference photograph are given in the PDF. Conference photograph
Modeling in transport phenomena a conceptual approach
Tosun, Ismail
2007-01-01
Modeling in Transport Phenomena, Second Edition presents and clearly explains with example problems the basic concepts and their applications to fluid flow, heat transfer, mass transfer, chemical reaction engineering and thermodynamics. A balanced approach is presented between analysis and synthesis, students will understand how to use the solution in engineering analysis. Systematic derivations of the equations and the physical significance of each term are given in detail, for students to easily understand and follow up the material. There is a strong incentive in science and engineering to
Modeling electrical dispersion phenomena in Earth materials
Directory of Open Access Journals (Sweden)
D. Patella
2008-06-01
Full Text Available It is illustrated that IP phenomena in rocks can be described using conductivity dispersion models deduced as solutions to a 2nd-order linear differential equation describing the motion of a charged particle immersed in an external electrical field. Five dispersion laws are discussed, namely: the non-resonant positive IP model, which leads to the classical Debye-type dispersion law and by extension to the Cole-Cole model, largely used in current practice; the non-resonant negative IP model, which allows negative chargeability values, known in metals at high frequencies, to be explained as an intrinsic physical property of earth materials in specific field cases; the resonant flat, positive or negative IP models, which can explain the presence of peak effects at specific frequencies superimposed on flat, positive or negative dispersion spectra.
Elementary particle physics and high energy phenomena
International Nuclear Information System (INIS)
Barker, A.R.; Cumalat, J.P.; De Alwis, S.P.; DeGrand, T.A.; Ford, W.T.; Mahanthappa, K.T.; Nauenberg, U.; Rankin, P.; Smith, J.G.
1992-06-01
Experimental and theoretical high-energy physics programs at the University of Colorado are reported. Areas of concentration include the following: study of the properties of the Z 0 with the SLD detector; fixed-target K-decay experiments; the R ampersand D program for the muon system: the SDC detector; high-energy photoproduction of states containing heavy quarks; electron--positron physics with the CLEO II detector at CESR; lattice QCD; and spin models and dynamically triangulated random surfaces. 24 figs., 2 tabs., 117 refs
Introduction to symmetry-breaking phenomena in physics
CERN. Geneva. Audiovisual Unit
2001-01-01
The notion of broken symmetries started slowly to emerge in the 19th century. The early studies of Pasteur on the parity asymmetry of life, the studies of Curie on piezoelectricity and on the symmetries of effects versus the symmetry of causes ( which clearly excluded spontaneous symmetry breaking), are important historical landmarks. However the possibility of spontaneous symmetry breaking within the usual principles of statistical mechanics, waited for the work of Peierls and Onsager. The whole theory of phase transitions and critical phenomena, as well as the construction of field theoretic models as long distance limit of yet unknown physics, relies nowadays on the concept of criticality associated to spontaneous symmetry breaking. The phenomena of Goldstone bosons, of Meissner-Higgs effects, are central to the theory of condensed matter as well as to particle physics. In cosmology as well, the various inflationary scenarios begin similarly with this same concept. The three lectures will provide a simple ...
Using Spatial Gradients to Model Localization Phenomena
Energy Technology Data Exchange (ETDEWEB)
D.J.Bammann; D.Mosher; D.A.Hughes; N.R.Moody; P.R.Dawson
1999-07-01
We present the final report on a Laboratory-Directed Research and Development project, Using Spatial Gradients to Model Localization Phenomena, performed during the fiscal years 1996 through 1998. The project focused on including spatial gradients in the temporal evolution equations of the state variables that describe hardening in metal plasticity models. The motivation was to investigate the numerical aspects associated with post-bifurcation mesh dependent finite element solutions in problems involving damage or crack propagation as well as problems in which strain Localizations occur. The addition of the spatial gradients introduces a mathematical length scale that eliminates the mesh dependency of the solution. In addition, new experimental techniques were developed to identify the physical mechanism associated with the numerical length scale.
Multiscale Modeling of Mesoscale and Interfacial Phenomena
Petsev, Nikolai Dimitrov
With rapidly emerging technologies that feature interfaces modified at the nanoscale, traditional macroscopic models are pushed to their limits to explain phenomena where molecular processes can play a key role. Often, such problems appear to defy explanation when treated with coarse-grained continuum models alone, yet remain prohibitively expensive from a molecular simulation perspective. A prominent example is surface nanobubbles: nanoscopic gaseous domains typically found on hydrophobic surfaces that have puzzled researchers for over two decades due to their unusually long lifetimes. We show how an entirely macroscopic, non-equilibrium model explains many of their anomalous properties, including their stability and abnormally small gas-side contact angles. From this purely transport perspective, we investigate how factors such as temperature and saturation affect nanobubbles, providing numerous experimentally testable predictions. However, recent work also emphasizes the relevance of molecular-scale phenomena that cannot be described in terms of bulk phases or pristine interfaces. This is true for nanobubbles as well, whose nanoscale heights may require molecular detail to capture the relevant physics, in particular near the bubble three-phase contact line. Therefore, there is a clear need for general ways to link molecular granularity and behavior with large-scale continuum models in the treatment of many interfacial problems. In light of this, we have developed a general set of simulation strategies that couple mesoscale particle-based continuum models to molecular regions simulated through conventional molecular dynamics (MD). In addition, we derived a transport model for binary mixtures that opens the possibility for a wide range of applications in biological and drug delivery problems, and is readily reconciled with our hybrid MD-continuum techniques. Approaches that couple multiple length scales for fluid mixtures are largely absent in the literature, and
Tramontin, Deise P; Gressler, Pablo D; Rörig, Leonardo R; Derner, Roberto B; Pereira-Filho, Jurandir; Radetski, Claudemir M; Quadri, Marintho B
2018-04-01
In recent years, numerous studies have justified the use of microalgae as a sustainable alternative for the generation of different types of fuels, food supplementation, and cosmetics, as well as bioremediation processes. To improve the cost/benefit ratio of microalgae mass production, many culture systems have been built and upgraded. Mathematical modeling the growth of different species in different systems has become an efficient and practical tool to understand both physical and biochemical phenomena in play during algae cultivation. In addition, growth modeling can guide design changes that lead to process optimization. In the present work, growth of the green microalga Scenedesmus obliquus was modeled in a hybrid photobioreactor that combines the characteristics of tubular photobioreactors (TPB) with thin-layer cascades (TLC). The system showed productivity greater than 8.0 g m -2 day -1 (dry mass) for CO 2 -fed cultures, and the model proved to be an accurate representation of experimental data with R 2 greater than 0.7 for all cases under variable conditions of temperature and irradiance to determine subsystem efficiency. Growth modeling also allowed growth prediction relative to the operating conditions of TLC, making it useful for estimating the system given other irradiance and temperature conditions, as well as other microalgae species. © 2017 Wiley Periodicals, Inc.
Ether and interpretation of some physical phenomena and concepts
International Nuclear Information System (INIS)
Rzayev, S.G.
2008-01-01
On the basis of the concept of existence of an ether representation about time, space, matters and physical field are profound and also the essence of such phenomena, as corpuscular - wave dualism, change of time, scale and mass at movement body's is opened. The opportunity of transition from probability-statistical interpretation of the quantum phenomena to Laplace's determinism is shown
GIS and dynamic phenomena modeling
Czech Academy of Sciences Publication Activity Database
Klimešová, Dana
2006-01-01
Roč. 4, č. 4 (2006), s. 11-15 ISSN 0139-570X Institutional research plan: CEZ:AV0Z10750506 Keywords : dynamic modelling * temporal analysis * dynamics evaluation * temporal space Subject RIV: BC - Control Systems Theory
Physical phenomena in new organic conductors
Energy Technology Data Exchange (ETDEWEB)
Gor' kov, L.P.
1984-11-01
Recent theoretical and experimental results on new synthetic metals: Bechgaard's salts: are reviewed. Superconductivity has been observed in these organic compounds for the first time. Furthermore, these materials exhibit such a variety of new and unusual physical properties that research on them is opening up a new branch of solid state physics.
Geochemical modelling: what phenomena are missing
International Nuclear Information System (INIS)
Jacquier, P.
1989-12-01
In the framework of safety assessment of radioactive waste disposal, retention phenomena are usually taken into account by the Kd concept. It is well recognized that this concept is not enough for safety assessment models, because of the several and strong assumptions which are involved in this kind of representation. One way to have a better representation of the retention phenomena, is to substitute for this Kd concept an explicit description of geochemical phenomena and then couple transport codes with geochemical codes in a fully or a two-step procedure. We use currently such codes, but the scope of this paper is to display the limits today of the geochemical modelling in connection with sites analysis for deep disposal. In this paper, we intend to give an overview of phenomena which are missing in the geochemical models, or which are not completely introduced in the models. We can distinguish, on one hand phenomena for which modelling concepts exist such as adsorption/desorption and, on the other hand, phenomena for which modelling concepts do not exist for the moment such as colloids, and complexation by polyelectrolyte solutions (organics). Moreover we have to take care of very low concentrations of radionuclides, which can be expected from the leaching processes in the repository. Under those conditions, some reactions may not occur. After a critical review of the involved phenomena, we intend to stress the main directions of the wishful evolution of the geochemical modelling. This evolution should improve substantially the quality of the above-mentioned site assessments
Elementary particle physics and high energy phenomena
International Nuclear Information System (INIS)
Barker, A.R.; Cumalat, J.P.; de Alwis, S.P.; DeGrand, T.A.; Ford, W.T.; Mahanthappa, K.T.; Nauenberg, U.; Rankin, P.; Smith, J.G.
1992-06-01
This report discusses the following research in high energy physics: the properties of the z neutral boson with the SLD detector; the research and development program for the SDC muon detector; the fixed-target k-decay experiments; the Rocky Mountain Consortium for HEP; high energy photoproduction of states containing heavy quarks; and electron-positron physics with the CLEO II and Mark II detectors. (LSP)
Elementary particle physics and high energy phenomena
Energy Technology Data Exchange (ETDEWEB)
Barker, A.R.; Cumalat, J.P.; de Alwis, S.P.; DeGrand, T.A.; Ford, W.T.; Mahanthappa, K.T.; Nauenberg, U.; Rankin, P.; Smith, J.G.
1992-06-01
This report discusses the following research in high energy physics: the properties of the z neutral boson with the SLD detector; the research and development program for the SDC muon detector; the fixed-target k-decay experiments; the Rocky Mountain Consortium for HEP; high energy photoproduction of states containing heavy quarks; and electron-positron physics with the CLEO II and Mark II detectors. (LSP).
Flavour Physics and Implication for New Phenomena
Isidori, Gino
2016-01-01
Flavour physics represents one of the most interesting and, at the same time, less understood sector of the Standard Theory. On the one hand, the peculiar pattern of quark and lepton masses, and their mixing angles, may be the clue to some new dynamics occurring at high-energy scales. On the other hand, the strong suppression of flavour-changing neutral-current processes, predicted by the Standard Theory and confirmed by experiments, represents a serious challenge to extend the Theory. This article reviews both these aspects of flavour physics from a theoretical perspective.
[Spin dependent phenomena in medium energy physics
International Nuclear Information System (INIS)
Souder, P.A.
1992-11-01
The Syracuse University Medium Energy Physics Group was actively engaged in several research projects. A laser was used to polarize muonic atoms with the goal of measuring fundamental spin-dependent parameters in the reaction μ - + 3 He → 3 H + ν. Time-averaged polarizations of 26.8±2.3% were achieved for the muon in muonic 3 He. The new approach uses atomic spin-dependent reactions between laser polarized Rb vapor and muonic helium. To exploit these high polarizations in a muon capture experiment an ion chamber which will detect the recoil tritons and also serve as a polarizing cell. Final data-taking will begin for an experiment to measure the spin-dependent structure functions of the neutron. A 288-element hodoscope system which features good timing and precise mechanical tolerances was constructed and evaluated
Modelling of flow phenomena during DC casting
Zuidema, J.
2005-01-01
Modelling of Flow Phenomena during DC Casting Jan Zuidema The production of aluminium ingots, by semi-continuous casting, is a complex process. DC Casting stands for direct chill casting. During this process liquid aluminium transforms to solid aluminium while cooling down. This is not an
All basic condensed matter physics phenomena and notions mirror ...
Indian Academy of Sciences (India)
light harvesting in biological photosynthesis, of mesoscopic exciton condensation related phenomena at room temperature. Keywords. Condensed matter physics; magnetic crystals in biology; excitons and photosynthesis. PACS Nos 87.10. ..... Figure 1. Schematic diagram of the light harvesting complex containing LH1 and.
A LCIA Model Considering Pollution Transfer Phenomena
Yu, Xi; Sekhari, Aicha; Nongaillard, Antoine; Bouras, Abdelaziz; Yu, Suiran; Yang, Qingyan
2013-01-01
Part 7: PLM and Influence of/from Social Networks; International audience; Due to market pressure and government regulations, environmental consciousness in manufacturing is becoming increasingly important. Currently, the global environmental impact (EI) of a product is a crucial criterion to judge its environmental performance. Many models were proposed in the last three decades to evaluate the global EI of products, but none of them considers the pollution transfer phenomena (PTP) of produc...
Magnetohydrodynamic (MHD) modelling of solar active phenomena via numerical methods
Wu, S. T.
1988-01-01
Numerical ideal MHD models for the study of solar active phenomena are summarized. Particular attention is given to the following physical phenomena: (1) local heating of a coronal loop in an isothermal and stratified atmosphere, and (2) the coronal dynamic responses due to magnetic field movement. The results suggest that local heating of a magnetic loop will lead to the enhancement of the density of the neighboring loops through MHD wave compression. It is noted that field lines can be pinched off and may form a self-contained magnetized plasma blob that may move outward into interplanetary space.
Mesoscopic Modeling of Multiphysicochemical Transport Phenomena in Porous Media
Directory of Open Access Journals (Sweden)
Qinjun Kang
2010-01-01
Full Text Available We present our recent progress on mesoscopic modeling of multiphysicochemical transport phenomena in porous media based on the lattice Boltzmann method. Simulation examples include injection of CO2-saturated brine into a limestone rock, two-phase behavior and flooding phenomena in polymer electrolyte fuel cells, and electroosmosis in homogeneously charged porous media. It is shown that the lattice Boltzmann method can account for multiple, coupled physicochemical processes in these systems and can shed some light on the underlying physics occurring at the fundamental scale. Therefore, it can be a potential powerful numerical tool to analyze multiphysicochemical processes in various energy, earth, and environmental systems.
Physically vapor deposited coatings on tools: performance and wear phenomena
International Nuclear Information System (INIS)
Koenig, W.; Fritsch, R.; Kammermeier, D.
1991-01-01
Coatings produced by physical vapor deposition (PVD) enhance the performance of tools for a broad variety of production processes. In addition to TiN, nowadays (Ti,Al)N and Ti(C,N) coated tools are available. This gives the opportunity to compare the performance of different coatings under identical machining conditions and to evaluate causes and phenomena of wear. TiN, (Ti,Al)N and Ti(C,N) coatings on high speed steel (HSS) show different performances in milling and turning of heat treated steel. The thermal and frictional properties of the coating materials affect the structure, the thickness and the flow of the chips, the contact area on the rake face and the tool life. Model tests show the influence of internal cooling and the thermal conductivity of coated HSS inserts. TiN and (Ti,Zr)N PVD coatings on cemented carbides were examined in interrupted turning and in milling of heat treated steel. Experimental results show a significant influence of typical time-temperature cycles of PVD and chemical vapor deposition (CVD) coating processes on the physical data and on the performance of the substrates. PVD coatings increase tool life, especially towards lower cutting speeds into ranges which cannot be applied with CVD coatings. The reason for this is the superior toughness of the PVD coated carbide. The combination of tough, micrograin carbide and PVD coating even enables broaching of case hardened sliding gears at a cutting speed of 66 m min -1 . (orig.)
Sixth Microgravity Fluid Physics and Transport Phenomena Conference Abstracts
Singh, Bhim (Compiler)
2002-01-01
The Sixth Microgravity Fluid Physics and Transport Phenomena Conference provides the scientific community the opportunity to view the current scope of the Microgravity Fluid Physics and Transport Phenomena Program, current research opportunities, and plans for the near future. The conference focuses not only on fundamental research but also on applications of this knowledge towards enabling future space exploration missions. A whole session dedicated to biological fluid physics shows increased emphasis that the program has placed on interdisciplinary research. The conference includes invited plenary talks, technical paper presentations, poster presentations, and exhibits. This TM is a compilation of abstracts of the papers and the posters presented at the conference. Web-based proceedings, including the charts used by the presenters, will be posted on the web shortly after the conference.
Simple models of equilibrium and nonequilibrium phenomena
International Nuclear Information System (INIS)
Lebowitz, J.L.
1987-01-01
This volume consists of two chapters of particular interest to researchers in the field of statistical mechanics. The first chapter is based on the premise that the best way to understand the qualitative properties that characterize many-body (i.e. macroscopic) systems is to study 'a number of the more significant model systems which, at least in principle are susceptible of complete analysis'. The second chapter deals exclusively with nonequilibrium phenomena. It reviews the theory of fluctuations in open systems to which they have made important contributions. Simple but interesting model examples are emphasised
Modelling of thermohydraulic emergency core cooling phenomena
International Nuclear Information System (INIS)
Yadigaroglu, G.; Andreani, M.; Lewis, M.J.
1990-10-01
The codes used in the early seventies for safety analysis and licensing were based either on the homogeneous model of two-phase flow or on the so-called separate-flow models, which are mixture models accounting, however, for the difference in average velocity between the two phases. In both cases the behavior of the mixture is prescribed a priori as a function of local parameters such as the mass flux and the quality. The modern best-estimate codes used for analyzing LWR LOCA's and transients are often based on a two-fluid or 6-equation formulation of the conservation equations. In this case the conservation equations are written separately for each phase; the mixture is allowed to evolve on its own, governed by the interfacial exchanges of mass, momentum and energy between the phases. It is generally agreed that such relatively sophisticated 6-equation formulations of two-phase flow are necessary for the correct modelling of a number of phenomena and situations arising in LWR accidental situations. They are in particular indispensible for the analysis of stratified or countercurrent flows and of situations in which large departures from thermal and velocity equilibrium exist. This report will be devoted to a discussion of the need for, the capacity and the limitations of the two-phase flow models (with emphasis on the 6-equation formulations) in modelling these two-phase flow and heat transfer phenomena and/or different core cooling situations. 18 figs., 1 tab., 72 refs
Two-Stage Modelling Of Random Phenomena
Barańska, Anna
2015-12-01
The main objective of this publication was to present a two-stage algorithm of modelling random phenomena, based on multidimensional function modelling, on the example of modelling the real estate market for the purpose of real estate valuation and estimation of model parameters of foundations vertical displacements. The first stage of the presented algorithm includes a selection of a suitable form of the function model. In the classical algorithms, based on function modelling, prediction of the dependent variable is its value obtained directly from the model. The better the model reflects a relationship between the independent variables and their effect on the dependent variable, the more reliable is the model value. In this paper, an algorithm has been proposed which comprises adjustment of the value obtained from the model with a random correction determined from the residuals of the model for these cases which, in a separate analysis, were considered to be the most similar to the object for which we want to model the dependent variable. The effect of applying the developed quantitative procedures for calculating the corrections and qualitative methods to assess the similarity on the final outcome of the prediction and its accuracy, was examined by statistical methods, mainly using appropriate parametric tests of significance. The idea of the presented algorithm has been designed so as to approximate the value of the dependent variable of the studied phenomenon to its value in reality and, at the same time, to have it "smoothed out" by a well fitted modelling function.
Social phenomena from data analysis to models
Perra, Nicola
2015-01-01
This book focuses on the new possibilities and approaches to social modeling currently being made possible by an unprecedented variety of datasets generated by our interactions with modern technologies. This area has witnessed a veritable explosion of activity over the last few years, yielding many interesting and useful results. Our aim is to provide an overview of the state of the art in this area of research, merging an extremely heterogeneous array of datasets and models. Social Phenomena: From Data Analysis to Models is divided into two parts. Part I deals with modeling social behavior under normal conditions: How we live, travel, collaborate and interact with each other in our daily lives. Part II deals with societal behavior under exceptional conditions: Protests, armed insurgencies, terrorist attacks, and reactions to infectious diseases. This book offers an overview of one of the most fertile emerging fields bringing together practitioners from scientific communities as diverse as social sciences, p...
Space Commercial Opportunities for Fluid Physics and Transport Phenomena Applications
Gavert, R.
2000-01-01
Microgravity research at NASA has been an undertaking that has included both science and commercial approaches since the late 80s and early 90s. The Fluid Physics and Transport Phenomena community has been developed, through NASA's science grants, into a valuable base of expertise in microgravity science. This was achieved through both ground and flight scientific research. Commercial microgravity research has been primarily promoted thorough NASA sponsored Centers for Space Commercialization which develop cost sharing partnerships with industry. As an example, the Center for Advanced Microgravity Materials Processing (CAMMP)at Northeastern University has been working with cost sharing industry partners in developing Zeolites and zeo-type materials as an efficient storage medium for hydrogen fuel. Greater commercial interest is emerging. The U.S. Congress has passed the Commercial Space Act of 1998 to encourage the development of a commercial space industry in the United States. The Act has provisions for the commercialization of the International Space Station (ISS). Increased efforts have been made by NASA to enable industrial ventures on-board the ISS. A Web site has been established at http://commercial/nasa/gov which includes two important special announcements. One is an open request for entrepreneurial offers related to the commercial development and use of the ISS. The second is a price structure and schedule for U.S. resources and accommodations. The purpose of the presentation is to make the Fluid Physics and Transport Phenomena community, which understands the importance of microgravity experimentation, aware of important aspects of ISS commercial development. It is a desire that this awareness will be translated into a recognition of Fluid Physics and Transport Phenomena application opportunities coordinated through the broad contacts of this community with industry.
Impact of measurable physical phenomena on contact thermal comfort
Fojtlín, Miloš; Pokorný, Jan; Fišer, Jan; Toma, Róbert; Tuhovčák, Ján
Cabin HVAC (Heating Ventilation and Air-conditioning) systems have become an essential part of personal vehicles as demands for comfortable transport are still rising. In fact, 85 % of the car trips in Europe are shorter than 18 km and last only up to 30 minutes. Under such conditions, the HVAC unit cannot often ensure desired cabin environment and passengers are prone to experience thermal stress. For this reason, additional comfort systems, such as heated or ventilated seats, are available on the market. However, there is no straightforward method to evaluate thermal comfort at the contact surfaces nowadays. The aim of this work is to summarise information about heated and ventilated seats. These technologies use electrical heating and fan driven air to contact area in order to achieve enhanced comfort. It is also expected, that such measures may contribute to lower energy consumption. Yet, in real conditions it is almost impossible to measure the airflow through the ventilated seat directly. Therefore, there is a need for an approach that would correlate measurable physical phenomena with thermal comfort. For this reason, a method that exploits a measurement of temperatures and humidity at the contact area is proposed. Preliminary results that correlate comfort with measurable physical phenomena are demonstrated.
Impact of measurable physical phenomena on contact thermal comfort
Directory of Open Access Journals (Sweden)
Fojtlín Miloš
2017-01-01
Full Text Available Cabin HVAC (Heating Ventilation and Air-conditioning systems have become an essential part of personal vehicles as demands for comfortable transport are still rising. In fact, 85 % of the car trips in Europe are shorter than 18 km and last only up to 30 minutes. Under such conditions, the HVAC unit cannot often ensure desired cabin environment and passengers are prone to experience thermal stress. For this reason, additional comfort systems, such as heated or ventilated seats, are available on the market. However, there is no straightforward method to evaluate thermal comfort at the contact surfaces nowadays. The aim of this work is to summarise information about heated and ventilated seats. These technologies use electrical heating and fan driven air to contact area in order to achieve enhanced comfort. It is also expected, that such measures may contribute to lower energy consumption. Yet, in real conditions it is almost impossible to measure the airflow through the ventilated seat directly. Therefore, there is a need for an approach that would correlate measurable physical phenomena with thermal comfort. For this reason, a method that exploits a measurement of temperatures and humidity at the contact area is proposed. Preliminary results that correlate comfort with measurable physical phenomena are demonstrated.
Ultrafast phenomena in molecular sciences femtosecond physics and chemistry
Bañares, Luis
2014-01-01
This book presents the latest developments in Femtosecond Chemistry and Physics for the study of ultrafast photo-induced molecular processes. Molecular systems, from the simplest H2 molecule to polymers or biological macromolecules, constitute central objects of interest for Physics, Chemistry and Biology, and despite the broad range of phenomena that they exhibit, they share some common behaviors. One of the most significant of those is that many of the processes involving chemical transformation (nuclear reorganization, bond breaking, bond making) take place in an extraordinarily short time, in or around the femtosecond temporal scale (1 fs = 10-15 s). A number of experimental approaches - very particularly the developments in the generation and manipulation of ultrashort laser pulses - coupled with theoretical progress, provide the ultrafast scientist with powerful tools to understand matter and its interaction with light, at this spatial and temporal scale. This book is an attempt to reunite some of the ...
International Nuclear Information System (INIS)
Rauck, St.
2000-10-01
The aim of this work is to develop a scheme for experimental reactors, based on transport equations. This type of reactors is characterized by a small core, a complex, very heterogeneous geometry and a large leakage. The possible insertion of neutron beams in the reflector and the presence of absorbers in the core increase the difficulty of the 3D-geometrical description and the physical modeling of the component parameters of the reactor. The Orphee reactor has been chosen for our study. Physical models (homogenization, collapsing cross section in few groups, albedo multigroup condition) have been developed in the APOLLO2 and CRONOS2 codes to calculate flux and power maps in a 3D-geometry, with different burnup and through transport equations. Comparisons with experimental measurements have shown the interest of taking into account anisotropy, steep flux gradients by using Sn methods, and on the other hand using a 12-group cross section library. The modeling of neutron beams has been done outside the core modeling through Monte Carlo calculations and with the total geometry, including a large thickness of heavy water. Thanks to this calculations, one can evaluate the neutron beams anti-reactivity and determinate the core cycle. We assure these methods more accurate than usual transport-diffusion calculations will be used for the conception of new research reactors. (author)
Proceedings of the physical phenomena at high magnetic fields - II
Energy Technology Data Exchange (ETDEWEB)
Fisk, Z.; Gor`kov, L.; Meltzer, D.; Schrieffer, R. [eds.
1996-12-31
Physical Phenomena at High Magnetic Fields-II was the second conference sponsored by the National High Magnetic Field Laboratory in Tallahassee, FL. The success of the first conference encouraged the Laboratory to once again bring together experts in scientific research areas where high magnetic fields play an important role, to critically assess the current status of research in these areas, and discuss promising new directions in science, as well as applications which are at the forefront of these fields. For the Laboratory, this conference has some additional significance. The Laboratory had just completed its construction stage and full scale scientific efforts were already underway. The Laboratory especially benefited from the invited lectures, original presentations, and open discussions of the conference participants. The Laboratory intends to continue this tradition and host the conference every three years. Separate papers from this proceedings were indexed to the energy database.
Modeling as an Anchoring Scientific Practice for Explaining Friction Phenomena
Neilson, Drew; Campbell, Todd
2017-12-01
Through examining the day-to-day work of scientists, researchers in science studies have revealed how models are a central sense-making practice of scientists as they construct and critique explanations about how the universe works. Additionally, they allow predictions to be made using the tenets of the model. Given this, alongside research suggesting that engaging students in developing and using models can have a positive effect on learning in science classrooms, the recent national standards documents in science education have identified developing and using models as an important practice students should engage in as they apply and refine their ideas with peers and teachers in explaining phenomena or solving problems in classrooms. This article details how students can be engaged in developing and using models to help them make sense of friction phenomena in a high school conceptual physics classroom in ways that align with visions for teaching and learning outlined in the Next Generation Science Standards. This particular unit has been refined over several years to build on what was initially an inquiry-based unit we have described previously. In this latest iteration of the friction unit, students developed and refined models through engaging in small group and whole class discussions and investigations.
Modeling transport phenomena and uncertainty quantification in solidification processes
Fezi, Kyle S.
Direct chill (DC) casting is the primary processing route for wrought aluminum alloys. This semicontinuous process consists of primary cooling as the metal is pulled through a water cooled mold followed by secondary cooling with a water jet spray and free falling water. To gain insight into this complex solidification process, a fully transient model of DC casting was developed to predict the transport phenomena of aluminum alloys for various conditions. This model is capable of solving mixture mass, momentum, energy, and species conservation equations during multicomponent solidification. Various DC casting process parameters were examined for their effect on transport phenomena predictions in an alloy of commercial interest (aluminum alloy 7050). The practice of placing a wiper to divert cooling water from the ingot surface was studied and the results showed that placement closer to the mold causes remelting at the surface and increases susceptibility to bleed outs. Numerical models of metal alloy solidification, like the one previously mentioned, are used to gain insight into physical phenomena that cannot be observed experimentally. However, uncertainty in model inputs cause uncertainty in results and those insights. The analysis of model assumptions and probable input variability on the level of uncertainty in model predictions has not been calculated in solidification modeling as yet. As a step towards understanding the effect of uncertain inputs on solidification modeling, uncertainty quantification (UQ) and sensitivity analysis were first performed on a transient solidification model of a simple binary alloy (Al-4.5wt.%Cu) in a rectangular cavity with both columnar and equiaxed solid growth models. This analysis was followed by quantifying the uncertainty in predictions from the recently developed transient DC casting model. The PRISM Uncertainty Quantification (PUQ) framework quantified the uncertainty and sensitivity in macrosegregation, solidification
Contribution to the study of multi-physical phenomena in cementitious materials
International Nuclear Information System (INIS)
Bary, B.
2010-09-01
This document is a synthesis of the applied research studies undertaken by the author during ten years, first at the University of Marne-La-Vallee during the period 1999-2002, then at the CEA. These studies concern the modeling and the numerical simulations of the cementitious materials behavior subjected on the one hand to moderate thermomechanical and hydric loadings, and on the other hand to chemical attacks due to the migration of calcium, carbonate and sulfate ions. The developed approaches may be viewed as multi-physical in the sense that the models used for describing the behavior couple various fields and phenomena such as mechanics, thermal, hydric and ionic transfers, and chemistry. In addition, analytical up-scaling techniques are applied to estimate the physical properties associated with these phenomena (mechanical, hydraulic and diffusive parameters) as a function of the microstructure and the hydric state of the material. (author)
Foam rheology: a model of viscous phenomena
International Nuclear Information System (INIS)
Kraynik, A.M.; Hansen, M.G.
1987-01-01
A theoretical model for foam rheology that includes viscous forces is developed by considering the deformation of two-dimensional, spatially periodic cells in simple shearing and planar extensional flow. The undeformed hexagonal cells are separated by thin liquid films. Plateau border curvature and liquid drainage between films is neglected. Interfacial tension and viscous tractions due to stretching lamellar liquid determine the individual film tensions. The network motion is described by a system of nonlinear ordinary differential equations for which numerical solutions are obtained. Coalescense and disproportionation of Plateau borders results in the relative separation of cells and provides a mechanism for yielding and flow. This process is assumed to occur when a film's length reduces to its thickness. The time and position dependence of the cell-scale dynamics are computed explicitly. The effective continuum stress of the foam is described by instantaneous and time-averaged quantities. The capillary number, a dimensionless deformation rate, represents the relative importance of viscous and surface tension effects. The small-capillary-number or quasistatic response determines a yield stress. The dependence of the shear and normal stress material functions upon deformation rate, foam structure and physical properties is determined. A plausible mechanism for shear-induced material failure, which would determine a shear strength, is revealed for large capillary numbers. The mechanism involves large cell distortion and film thinning, which provide favorable conditions for film rupture
The mysteries of leptons. New physics and unexplained phenomena
Energy Technology Data Exchange (ETDEWEB)
Merle, Alexander
2009-12-09
This doctoral thesis deals with the mysteries of the leptonic sector of the Standard Model of Elementary Particle Physics. After giving a short overview about the Standard Model itself, the text starts with introducing the so-called ''GSI anomaly'', the observation of a periodic modulation of the exponential decay law, which is still unexplained and has erroneously been attributed to neutrino oscillations. It is argued why this interpretation is incorrect and several further aspects of the phenomenon are discussed. Afterwards two topics of New Physics beyond the Standard Model are treated, double beta processes and lepton flavour violation. Some important phenomenological aspects of the former are discussed before performing a detailed calculation of the radiative process of neutrino-less double electron capture. In spite of the tiny rates, a detailed understanding of this process is important for setting proper experimental limits. The last part of the thesis starts with very general (and nearly model-independent) constraints for lepton flavour conservation, before discussing the interplay of structure and freedom in the Yukawa sector when a model is confronted with phenomenology. We also comment on a new mechanism that can indeed introduce some realistic structures leading to lepton flavour violating effects. (orig.)
Rethinking earthquake-related DC-ULF electromagnetic phenomena: towards a physics-based approach
Directory of Open Access Journals (Sweden)
Q. Huang
2011-11-01
Full Text Available Numerous electromagnetic changes possibly related with earthquakes have been independently reported and have even been attempted to apply to short-term prediction of earthquakes. However, there are active debates on the above issue because the seismogenic process is rather complicated and the studies have been mainly empirical (i.e. a kind of experience-based approach. Thus, a physics-based study would be helpful for understanding earthquake-related electromagnetic phenomena and strengthening their applications. As a potential physics-based approach, I present an integrated research scheme, taking into account the interaction among observation, methodology, and physical model. For simplicity, this work focuses only on the earthquake-related DC-ULF electromagnetic phenomena. The main approach includes the following key problems: (1 how to perform a reliable and appropriate observation with some clear physical quantities; (2 how to develop a robust methodology to reveal weak earthquake-related electromagnetic signals from noisy background; and (3 how to develop plausible physical models based on theoretical analyses and/or laboratory experiments for the explanation of the earthquake-related electromagnetic signals observed in the field conditions.
Understanding the Physical Optics Phenomena by Using a Digital Application for Light Propagation
Energy Technology Data Exchange (ETDEWEB)
Sierra-Sosa, Daniel-Esteban; Angel-Toro, Luciano, E-mail: dsierras@eafit.edu.co, E-mail: langel@eafit.edu.co [Grupo de Optica Aplicada, Universidad EAFIT, 1 Medellin (Colombia)
2011-01-01
Understanding the light propagation on the basis of the Huygens-Fresnel principle stands for a fundamental factor for deeper comprehension of different physical optics related phenomena like diffraction, self-imaging, image formation, Fourier analysis and spatial filtering. This constitutes the physical approach of the Fourier optics whose principles and applications have been developed since the 1950's. Both for analytical and digital applications purposes, light propagation can be formulated in terms of the Fresnel Integral Transform. In this work, a digital optics application based on the implementation of the Discrete Fresnel Transform (DFT), and addressed to serve as a tool for applications in didactics of optics is presented. This tool allows, at a basic and intermediate learning level, exercising with the identification of basic phenomena, and observing changes associated with modifications of physical parameters. This is achieved by using a friendly graphic user interface (GUI). It also assists the user in the development of his capacity for abstracting and predicting the characteristics of more complicated phenomena. At an upper level of learning, the application could be used to favor a deeper comprehension of involved physics and models, and experimenting with new models and configurations. To achieve this, two characteristics of the didactic tool were taken into account when designing it. First, all physical operations, ranging from simple diffraction experiments to digital holography and interferometry, were developed on the basis of the more fundamental concept of light propagation. Second, the algorithm was conceived to be easily upgradable due its modular architecture based in MATLAB (registered) software environment. Typical results are presented and briefly discussed in connection with didactics of optics.
Understanding the Physical Optics Phenomena by Using a Digital Application for Light Propagation
International Nuclear Information System (INIS)
Sierra-Sosa, Daniel-Esteban; Angel-Toro, Luciano
2011-01-01
Understanding the light propagation on the basis of the Huygens-Fresnel principle stands for a fundamental factor for deeper comprehension of different physical optics related phenomena like diffraction, self-imaging, image formation, Fourier analysis and spatial filtering. This constitutes the physical approach of the Fourier optics whose principles and applications have been developed since the 1950's. Both for analytical and digital applications purposes, light propagation can be formulated in terms of the Fresnel Integral Transform. In this work, a digital optics application based on the implementation of the Discrete Fresnel Transform (DFT), and addressed to serve as a tool for applications in didactics of optics is presented. This tool allows, at a basic and intermediate learning level, exercising with the identification of basic phenomena, and observing changes associated with modifications of physical parameters. This is achieved by using a friendly graphic user interface (GUI). It also assists the user in the development of his capacity for abstracting and predicting the characteristics of more complicated phenomena. At an upper level of learning, the application could be used to favor a deeper comprehension of involved physics and models, and experimenting with new models and configurations. To achieve this, two characteristics of the didactic tool were taken into account when designing it. First, all physical operations, ranging from simple diffraction experiments to digital holography and interferometry, were developed on the basis of the more fundamental concept of light propagation. Second, the algorithm was conceived to be easily upgradable due its modular architecture based in MATLAB (registered) software environment. Typical results are presented and briefly discussed in connection with didactics of optics.
Nonlinear structural mechanics theory, dynamical phenomena and modeling
Lacarbonara, Walter
2013-01-01
Nonlinear Structural Mechanics: Theory, Dynamical Phenomena and Modeling offers a concise, coherent presentation of the theoretical framework of nonlinear structural mechanics, computational methods, applications, parametric investigations of nonlinear phenomena and their mechanical interpretation towards design. The theoretical and computational tools that enable the formulation, solution, and interpretation of nonlinear structures are presented in a systematic fashion so as to gradually attain an increasing level of complexity of structural behaviors, under the prevailing assumptions on the geometry of deformation, the constitutive aspects and the loading scenarios. Readers will find a treatment of the foundations of nonlinear structural mechanics towards advanced reduced models, unified with modern computational tools in the framework of the prominent nonlinear structural dynamic phenomena while tackling both the mathematical and applied sciences. Nonlinear Structural Mechanics: Theory, Dynamical Phenomena...
All basic condensed matter physics phenomena and notions mirror ...
Indian Academy of Sciences (India)
A few billion years of evolutionary time and the complex process of 'selection' has given biology an opportunity to explore a variety of condensed matter phenomena and situations, some of which have been discovered by humans in the laboratory, that too only in extreme non-biological conditions such as low temperatures, ...
Nonlinear dynamic phenomena in the beer model
DEFF Research Database (Denmark)
Mosekilde, Erik; Laugesen, Jakob Lund
2007-01-01
The production-distribution system or "beer game" is one of the most well-known system dynamics models. Notorious for the complex dynamics it produces, the beer game has been used for nearly five decades to illustrate how structure generates behavior and to explore human decision making. Here we ...... in models that use piecewise-linear functions to represent nonlinearities are likely to show similar qualitative differences from the bifurcations known from smooth systems.......The production-distribution system or "beer game" is one of the most well-known system dynamics models. Notorious for the complex dynamics it produces, the beer game has been used for nearly five decades to illustrate how structure generates behavior and to explore human decision making. Here we...... present a formal bifurcation analysis to analyse the complex dynamics produced by the model. Consistent with the rules of the game, the model constitutes a piecewise-linear map with nonlinearities arising from non-negativity constraints. The bifurcations that occur in piecewise-linear systems...
Modeling Optical Lithography Physics
Neureuther, Andrew R.; Rubinstein, Juliet; Chin, Eric; Wang, Lynn; Miller, Marshal; Clifford, Chris; Yamazoe, Kenji
2010-06-01
Key physical phenomena associated with resists, illumination, lenses and masks are used to show the progress in models and algorithms for modeling optical projection printing as well as current simulation challenges in managing process complexity for manufacturing. The amazing current capability and challenges for projection printing are discussed using the 22 nm device generation. A fundamental foundation for modeling resist exposure, partial coherent imaging and defect printability is given. The technology innovations of resolution enhancement and chemically amplified resist systems and their modeling challenges are overviewed. Automated chip-level applications in pattern pre-compensation and design-anticipation of residual process variations require new simulation approaches.
Nonequilibrium phenomena in chiral physics and hot gauge theories
Sivaramakrishnan, Prem Kumar
We develop and implement a consistent quantum field theory framework for analysing a variety of non- equilibrium, non-perturbative phenomena associated with the Chiral Phase transition and gauge theories at finite temperature. We present a first principles calculation (within the framework of the gauged linear sigma-model) of the photon production rate during this phase transition and in the process we develop a new, improved approach towards quantum kinetics which goes far beyond standard Boltzmann-like equations. We also study the anomalous coupling of the neutral pion field to electromagnetism and find that under certain conditions, this coupling can lead to photon production via a process of parametric amplification which is intrinsically a non- perturbative phenomenon. The resulting spectrum of photons has very distinctive peaks and exhibits a polarisation asymmetry. We argue that these electromagnetic signals could be striking signatures of the Chiral Phase transition out-of-equilibrium. Motivated by certain issues associated with baryogenesis in the hot electroweak theory and with a view towards gaining an understanding of the dynamics of soft collective excitations in the Quark-Gluon Plasma, we turn our attention to the nonequilibrium dynamics of soft gauge field configurations in hot scalar QED. We argue that the dynamics of the long-wavelength excitations is determined by the Hard Thermal Loop self-energy which has the same form in both scalar QED and the non-Abelian case. We find that the relaxation of these excitations proceeds via power laws which are completely determined by the spectral density at the thresholds of Landau damping cuts. We then show that a Markovian approximation fails to describe the dynamics both at short and long times. We also introduce a new kinetic approach that goes beyond the standard Boltzmann equation by incorporating off-shell processes and find that the distribution function for soft quasiparticles relaxes with a power law
Clear and fuzzy fractal models of spreading dangerous environmental phenomena
Directory of Open Access Journals (Sweden)
A.E. Guy
2006-04-01
Full Text Available This article is devoted to investigation of possibility of widening models of spreading dangerous environmental phenomena, in particular Grassberger’s models, on the base of notion of fuzzy fractal sets introduced by one of the authors. Basic concepts from the theory of fuzzy fractals are considered.
Modelling of transport phenomena and defects in crystal growth ...
Indian Academy of Sciences (India)
A brief review of single crystal growth techniques and the associated problems is presented. Emphasis is placed on models for various transport and defect phenomena involoved in the growth process with the ultimate aim of integrating them into a comprehensive numerical model. The sources of dislocation nucleation in ...
Ancient Chinese observations of physical phenomena attending solar eclipses
International Nuclear Information System (INIS)
Wang, P.K.; Siscoe, G.L.
1980-01-01
The realization that solar activity probably undergoes changes in qualitative character on time scales greater than the 11 or 22 year cycle but short compared to the duration of recorded history gives renewed importance to historical documents describing the state of solar activity. Modern eclipse observation reveal the presence of solar acitivity through the appearance of coronal structures and prominences. It has been widely remarked that eclipse records prior to the 18th century are uniformly silent on these conspicuous solar eclipse features, raising the possibility, however unlikely, that a change in solar activity has occurred which rendered them only recently noticeable. We present here material from ancient Chinese sources, primarily astrological, that describe phenomena attending solar eclipses that are almost certainly coronal structures and prominences. Thus, these aspects of the present character of solar activity have apparently occurred at other times in history, if not continuously. (orig.)
Searches for phenomena beyond the Standard Model at the Large ...
Indian Academy of Sciences (India)
Keywords. LHC; ATLAS; CMS; BSM; supersymmetry; exotic. Abstract. The LHC has delivered several fb-1 of data in spring and summer 2011, opening new windows of opportunity for discovering phenomena beyond the Standard Model. A summary of the searches conducted by the ATLAS and CMS experiments based on ...
Searches for phenomena beyond the Standard Model at the Large
Indian Academy of Sciences (India)
The LHC has delivered several fb-1 of data in spring and summer 2011, opening new windows of opportunity for discovering phenomena beyond the Standard Model. A summary of the searches conducted by the ATLAS and CMS experiments based on about 1 fb-1 of data is presented.
Modeling and simulation of transport phenomena in ionic gels
Leichsenring, Peter; Wallmersperger, Thomas
2015-04-01
Ionic hydrogels belong to the class of polyelectrolyte gels or ionic gels. Their ability to swell or shrink under different environmental conditions such as change of pH, ion concentration or temperature make them promising materials, e.g. for microsensoric or microactuatoric devices. The hydrogel swelling exhibits nonlinear effects due to the occurrence of different interacting transport phenomena. Numerical simulations are an essential part in the ongoing development of microsensors and microactuators. In order to determine transport effects due to diffusion, migration and convection a multiphase mesoscale model based on the Theory of Porous Media is applied. The governing field equations are solved in the transient regime by applying the Finite Element Method. By means of the derived numerical framework a detailed investigation of the different transport phenomena is carried out. Numerical experiments are performed to characterize the dominating transfer phenomena for ionic gels under chemical stimulation.
Singh, Bhim (Compiler)
2002-01-01
The Sixth Microgravity Fluid Physics and Transport Phenomena Conference provides the scientific community the opportunity to view the current scope of the Microgravity Fluid Physics and Transport Phenomena Program, current research opportunities, and plans for the near future. The conference focuses not only on fundamental research but also on applications of this knowledge towards enabling future space exploration missions. A whole session dedicated to biological fluid physics shows increased emphasis that the program has placed on interdisciplinary research. The conference includes invited plenary talks, technical paper presentations, poster presentations, and exhibits. This CP (conference proceeding) is a compilation of the abstracts, presentations, and posters presented at the conference.
Mesoscopic modeling of multi-physicochemical transport phenomena in porous media
Energy Technology Data Exchange (ETDEWEB)
Kang, Qinjin [Los Alamos National Laboratory; Wang, Moran [Los Alamos National Laboratory; Mukherjee, Partha P [Los Alamos National Laboratory; Lichtner, Peter C [Los Alamos National Laboratory
2009-01-01
We present our recent progress on mesoscopic modeling of multi-physicochemical transport phenomena in porous media based on the lattice Boltzmann method. Simulation examples include injection of CO{sub 2} saturated brine into a limestone rock, two-phase behavior and flooding phenomena in polymer electrolyte fuel cells, and electroosmosis in homogeneously charged porous media. It is shown that the lattice Boltzmann method can account for multiple, coupled physicochemical processes in these systems and can shed some light on the underlying physics occuning at the fundamental scale. Therefore, it can be a potential powerful numerical tool to analyze multi-physicochemical processes in various energy, earth, and environmental systems.
Basic physical phenomena, neutron production and scaling of the dense plasma focus
International Nuclear Information System (INIS)
Kaeppeler, H.J.
This paper presents an attempt at establishing a model theory for the dense plasma focus in order to present a consistent interpretation of the basic physical phenomena leading to neutron production from both acceleration and thermal processes. To achieve this, the temporal history of the focus is divided into the compression of the plasma sheath, a qiescent and very dense phase with ensuing expansion, and an instable phase where the focus plasma is disrupted by instabilities. Finally, the decay of density, velocity and thermal fields is considered. Under the assumption that Io 2 /sigmaoRo 2 = const and to/Tc = const, scaling laws for plasma focus devices are derived. It is shown that while generally the neutron yield scales with the fourth power of maximum current, neutron production from thermal processes becomes increasingly important for large devices, while in the small devices neutron production from acceleration processes is by far predominant. (orig.) [de
Possilibity of estimating payoff matrix from model for hit phenomena
International Nuclear Information System (INIS)
Ishii, Akira; Sakaidani, Shota; Iwanaga, Saori
2016-01-01
The conflicts of topics on social media is considered using an extended mathematical model based on the mathematical model for hit phenomena that has been used to analyze entertainment hits. The social media platform used in this study was blog. The calculation results shows examples of strong conflict, weak conflict, and no conflict cases. Since the conflict of two topics can be considered in the framework of game theory, the results can be used to determine each matrix element of the payoff matrix of game theory.
Simulation of thermohydraulic phenomena and model test for FBR
International Nuclear Information System (INIS)
Satoh, Kazuziro
1994-01-01
This paper summarizes the major thermohydraulic phenomena of FBRs and the conventional ways of their model tests, and introduces the recent findings regarding measurement technology and computational science. In the future commercial stage of FBRs, the design optimization will becomes important to improve economy and safety more and more. It is indispensable to use computational science to the plant design and safety evaluation. The most of the model tests will be replaced by the simulation analyses based on computational science. The measurement technology using ultrasonic and the numerical simulation with super parallel computing are considered to be the key technology to realize the design by analysis method. (author)
Singh, Bhim S.
1999-01-01
This paper provides an overview of the microgravity fluid physics and transport phenomena experiments planned for the International Spare Station. NASA's Office of Life and Microgravity Science and Applications has established a world-class research program in fluid physics and transport phenomena. This program combines the vast expertise of the world research community with NASA's unique microgravity facilities with the objectives of gaining new insight into fluid phenomena by removing the confounding effect of gravity. Due to its criticality to many terrestrial and space-based processes and phenomena, fluid physics and transport phenomena play a central role in the NASA's Microgravity Program. Through widely publicized research announcement and well established peer-reviews, the program has been able to attract a number of world-class researchers and acquired a critical mass of investigations that is now adding rapidly to this field. Currently there arc a total of 106 ground-based and 20 candidate flight principal investigators conducting research in four major thrust areas in the program: complex flows, multiphase flow and phase change, interfacial phenomena, and dynamics and instabilities. The International Space Station (ISS) to be launched in 1998, provides the microgravity research community with a unprecedented opportunity to conduct long-duration microgravity experiments which can be controlled and operated from the Principal Investigators' own laboratory. Frequent planned shuttle flights to the Station will provide opportunities to conduct many more experiments than were previously possible. NASA Lewis Research Center is in the process of designing a Fluids and Combustion Facility (FCF) to be located in the Laboratory Module of the ISS that will not only accommodate multiple users but, allow a broad range of fluid physics and transport phenomena experiments to be conducted in a cost effective manner.
Simulations of Heat Transport Phenomena in a Three-Dimensional Model of Knitted Fabric
Directory of Open Access Journals (Sweden)
Puszkarz A.K.
2016-09-01
Full Text Available The main goal of the current work is to analyse the three-dimensional approach for modelling knitted fabric structures for future analysis of physical properties and thermal phenomena. The introduced model assumes some simplification of morphology. First, fibres in knitted fabrics are described as monofilaments characterized by isotropic thermal properties. The current form of the considered knitted fabric is determined by morphological properties of the used monofilament and simplification of the stitch shape. This simplification was based on a particular technology for the knitting process that introduces both geometric parameters and physical material properties. Detailed descriptions of heat transfer phenomena can also be considered. A sensitivity analysis of the temperature field with respect to selected structural parameters was also performed.
The physics of nanoelectronics transport and fluctuation phenomena at low temperatures
Heikkila, Tero T
2013-01-01
Advances in nanotechnology have allowed physicists and engineers to miniaturize electronic structures to the limit where finite-size related phenomena start to impact their properties. This book discusses such phenomena and models made for their description. The book starts from the semiclassical description of nonequilibrium effects, details the scattering theory used for quantum transport calculations, and explains the main interference effects. It also describes how to treat fluctuations and correlations, how interactions affect transport through small islands, and how superconductivity modifies these effects. The last two chapters describe new emerging fields related with graphene and nanoelectromechanics. The focus of the book is on the phenomena rather than formalism, but the book still explains in detail the main models constructed for these phenomena. It also introduces a number of electronic devices, including the single-electron transistor, the superconducting tunnel junction refrigerator, and the s...
Modeling the Collision Phenomena of Ø11X19 Size Rolls
Directory of Open Access Journals (Sweden)
Tiberiu Manescu jr.
2011-09-01
Full Text Available This paper presents a numerical comparison using dynamic modeling techniques, of physical phenomena occurring at collisions between two rollers in a lot of distinct situations: impact on the edge at angles of 0°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80° and impact on generator. These situations occur frequently in the manufacturing process of small cylindrical rollers.
Radiation transport phenomena and modeling. Part A: Codes; Part B: Applications with examples
Energy Technology Data Exchange (ETDEWEB)
Lorence, L.J. Jr.; Beutler, D.E. [Sandia National Labs., Albuquerque, NM (United States). Simulation Technology Research Dept.
1997-09-01
This report contains the notes from the second session of the 1997 IEEE Nuclear and Space Radiation Effects Conference Short Course on Applying Computer Simulation Tools to Radiation Effects Problems. Part A discusses the physical phenomena modeled in radiation transport codes and various types of algorithmic implementations. Part B gives examples of how these codes can be used to design experiments whose results can be easily analyzed and describes how to calculate quantities of interest for electronic devices.
CFD modelling of insulation debris transport phenomena in water flow
Energy Technology Data Exchange (ETDEWEB)
Krepper, Eeckhard; Cartland-Glover, Gregory; Grahn, Alexander [Forschungszentrum Rossendorf e.V., Dresden (Germany). Inst. fuer Sicherheitsforschung
2009-11-15
The investigation of insulation debris generation, transport and sedimentation becomes important with regard to reactor safety research for PWR and BWR, when considering the long-term behaviour of emergency core cooling systems during all types of loss of coolant accidents. A joint research project on such questions is being performed in cooperation between the University of Applied Sciences Zittau/Goerlitz and the Forschungszentrum Dresden-Rossendorf. The project deals with the experimental investigation of particle transport phenomena in coolant flow and the development of CFD models for its description. While the experiments are performed at the University at Zittau/Goerlitz, the theoretical modelling efforts are concentrated at Forschungszentrum Dresden-Rossendorf. In the current paper the basic concepts for CFD modelling are described and feasibility studies are presented. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Barker, A.R.; Cumalat, J.P.; De Alwis, S.P.; DeGrand, T.A.; Ford, W.T.; Mahanthappa, K.T.; Nauenberg, U.; Rankin, P.; Smith, J.G.
1992-06-01
Experimental and theoretical high-energy physics programs at the University of Colorado are reported. Areas of concentration include the following: study of the properties of the Z[sup 0] with the SLD detector; fixed-target K-decay experiments; the R D program for the muon system: the SDC detector; high-energy photoproduction of states containing heavy quarks; electron--positron physics with the CLEO II detector at CESR; lattice QCD; and spin models and dynamically triangulated random surfaces. 24 figs., 2 tabs., 117 refs.
Polar Coordinate Lattice Boltzmann Kinetic Modeling of Detonation Phenomena
International Nuclear Information System (INIS)
Lin Chuan-Dong; Li Ying-Jun; Xu Ai-Guo; Zhang Guang-Cai
2014-01-01
A novel polar coordinate lattice Boltzmann kinetic model for detonation phenomena is presented and applied to investigate typical implosion and explosion processes. In this model, the change of discrete distribution function due to local chemical reaction is dynamically coupled into the modified lattice Boltzmann equation which could recover the Navier—Stokes equations, including contribution of chemical reaction, via the Chapman—Enskog expansion. For the numerical investigations, the main focuses are the nonequilibrium behaviors in these processes. The system at the disc center is always in its thermodynamic equilibrium in the highly symmetric case. The internal kinetic energies in different degrees of freedom around the detonation front do not coincide. The dependence of the reaction rate on the pressure, influences of the shock strength and reaction rate on the departure amplitude of the system from its local thermodynamic equilibrium are probed. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
Macroscopic Modeling of Transport Phenomena in Direct Methanol Fuel Cells
DEFF Research Database (Denmark)
Olesen, Anders Christian
An increasing need for energy efficiency and high energy density has sparked a growing interest in direct methanol fuel cells for portable power applications. This type of fuel cell directly generates electricity from a fuel mixture consisting of methanol and water. Although this technology...... for studying their transport. In this PhD dissertation the macroscopic transport phenomena governing direct methanol fuel cell operation are analyzed, discussed and modeled using the two-fluid approach in the computational fluid dynamics framework of CFX 14. The overall objective of this work is to extend...... the present fundamental understanding of direct methanol fuel cell operation by developing a three-dimensional, two-phase, multi-component, non-isotherm mathematical model including detailed non-ideal thermodynamics, non-equilibrium phase change and non-equilibrium sorption-desorption of methanol and water...
Modelling of particular phenomena observed in PANDA with Gothic
International Nuclear Information System (INIS)
Bandurski, Th.; Putz, F.; Andreani, M.; Analytis, M.
2000-01-01
PANDA is a large scale facility for investigating the long-term decay heat removal from the containment of a next generation 'passive' Advanced Light Water Reactor (ALWR). The first test series was aimed at the investigation of the long-term LOCA response of the Passive Containment Cooling System (PCCS) for the General Electric (GE) Simplified Boiling Water Reactor (SBWR). Recently, the facility is used in the framework of two European projects for investigating the performance of four passive cooling systems, i.e. the Building Condenser (BC) designed by Siemens for the SWR-1000 long-term containment cooling, the Passive Containment Cooling System for the European Simplified Boiling Water Reactor (ESBWR), the Containment Plate Condenser (CPC) and the Isolation Condenser (IC) for cooling of a BWR core. The PANDA tests have the dual objectives of improving confidence in the performance of the passive heat removal mechanisms underlying the design of the tested safety systems and extending the data base available for containment analysis code qualification. Among others, the containment analysis code Gothic was chosen for the analysis of particular phenomena observed during the PANDA tests. Ibis paper presents selected safety relevant phenomena observed in the PANDA tests and identified for the analyses and possible approaches for their modeling with Gothic. (author)
Physically realistic modeling of maritime training simulation
Cieutat , Jean-Marc
2003-01-01
Maritime training simulation is an important matter of maritime teaching, which requires a lot of scientific and technical skills.In this framework, where the real time constraint has to be maintained, all physical phenomena cannot be studied; the most visual physical phenomena relating to the natural elements and the ship behaviour are reproduced only. Our swell model, based on a surface wave simulation approach, permits to simulate the shape and the propagation of a regular train of waves f...
Modelling high strain rate phenomena in metal cutting simulation
International Nuclear Information System (INIS)
Wedberg, Dan; Svoboda, Ales; Lindgren, Lars-Erik
2012-01-01
Chip formation in metal cutting is associated with large strains and high strain rates, concentrated locally to deformation zones in front of the tool and beneath the cutting edge. Furthermore, dissipative plastic work and friction work generate high local temperatures. These phenomena together with numerical complications make modelling of metal cutting difficult. Material models, which are crucial in metal cutting simulations, are usually calibrated based on data from material testing. Nevertheless, the magnitude of strains and strain rates involved in metal cutting are several orders higher than those generated from conventional material testing. A highly desirable feature is therefore a material model that can be extrapolated outside the calibration range. In this study, two variants of a flow stress model based on dislocation density and vacancy concentration are used to simulate orthogonal metal cutting of AISI 316L stainless steel. It is found that the addition of phonon drag improves the results somewhat but the addition of this phenomenon still does not make it possible to extrapolate the constitutive model reliably outside its calibration range. (paper)
Proceedings of the Fourth Microgravity Fluid Physics and Transport Phenomena Conference
Singh, Bhim S. (Editor)
1999-01-01
This conference presents information to the scientific community on research results, future directions, and research opportunities in microgravity fluid physics and transport phenomena within NASA's microgravity research program. The conference theme is "The International Space Station." Plenary sessions provide an overview of the Microgravity Fluid Physics Program, the International Space Station and the opportunities ISS presents to fluid physics and transport phenomena researchers, and the process by which researchers may become involved in NASA's program, including information about the NASA Research Announcement in this area. Two plenary lectures present promising areas of research in electrohydrodynamics/electrokinetics in the movement of particles and in micro- and meso-scale effects on macroscopic fluid dynamics. Featured speakers in plenary sessions present results of recent flight experiments not heretofore presented. The conference publication consists of this book of abstracts and the full Proceedings of the 4th Microgravity Fluid Physics and Transport Phenomena Conference on CD-ROM, containing full papers presented at the conference (NASA/CP-1999-208526/SUPPL1).
Energy Technology Data Exchange (ETDEWEB)
Andersson, Martin; Yuan, Jinliang; Sunden, Bengt [Department of Energy Sciences, Lund University, SE-221 00 Lund (Sweden)
2010-05-15
A literature study is performed to compile the state-of-the-art, as well as future potential, in SOFC modeling. Principles behind various transport processes such as mass, heat, momentum and charge as well as for electrochemical and internal reforming reactions are described. A deeper investigation is made to find out potentials and challenges using a multiscale approach to model solid oxide fuel cells (SOFCs) and combine the accuracy at microscale with the calculation speed at macroscale to design SOFCs, based on a clear understanding of transport phenomena, chemical reactions and functional requirements. Suitable methods are studied to model SOFCs covering various length scales. Coupling methods between different approaches and length scales by multiscale models are outlined. Multiscale modeling increases the understanding for detailed transport phenomena, and can be used to make a correct decision on the specific design and control of operating conditions. It is expected that the development and production costs will be decreased and the energy efficiency be increased (reducing running cost) as the understanding of complex physical phenomena increases. It is concluded that the connection between numerical modeling and experiments is too rare and also that material parameters in most cases are valid only for standard materials and not for the actual SOFC component microstructures. (author)
Modeling brain resonance phenomena using a neural mass model.
Directory of Open Access Journals (Sweden)
Andreas Spiegler
2011-12-01
Full Text Available Stimulation with rhythmic light flicker (photic driving plays an important role in the diagnosis of schizophrenia, mood disorder, migraine, and epilepsy. In particular, the adjustment of spontaneous brain rhythms to the stimulus frequency (entrainment is used to assess the functional flexibility of the brain. We aim to gain deeper understanding of the mechanisms underlying this technique and to predict the effects of stimulus frequency and intensity. For this purpose, a modified Jansen and Rit neural mass model (NMM of a cortical circuit is used. This mean field model has been designed to strike a balance between mathematical simplicity and biological plausibility. We reproduced the entrainment phenomenon observed in EEG during a photic driving experiment. More generally, we demonstrate that such a single area model can already yield very complex dynamics, including chaos, for biologically plausible parameter ranges. We chart the entire parameter space by means of characteristic Lyapunov spectra and Kaplan-Yorke dimension as well as time series and power spectra. Rhythmic and chaotic brain states were found virtually next to each other, such that small parameter changes can give rise to switching from one to another. Strikingly, this characteristic pattern of unpredictability generated by the model was matched to the experimental data with reasonable accuracy. These findings confirm that the NMM is a useful model of brain dynamics during photic driving. In this context, it can be used to study the mechanisms of, for example, perception and epileptic seizure generation. In particular, it enabled us to make predictions regarding the stimulus amplitude in further experiments for improving the entrainment effect.
Artificially Structured Semiconductors to Model Novel Quantum Phenomena
Energy Technology Data Exchange (ETDEWEB)
Pinczuk, Aron [Columbia Univ., New York, NY (United States). Dept. of Applied Physics and Applied Mathematics; Wind, Shalom J. [Columbia Univ., New York, NY (United States). Dept. of Applied Physics and Applied Mathematics
2018-01-13
Award Period: September 1st, 2013 through February 15th, 2017 Submitted to the USDOE Office of Basic Energy Sciences By Aron Pinczuk and Shalom J. Wind Department of Applied Physics and Applied Mathematics Columbia University New York, NY 10027 January 2017 Award # DE-SC0010695 ABSTRACT Research in this project seeks to design, create and study a class of tunable artificial quantum structures in order to extend the range and scope of new and exciting physical phenomena and to explore the potential for new applications. Advanced nanofabrication was used to create an external potential landscape that acts as a lattice of confinement sites for electrons (and/or holes) in a two-dimensional electron gas in a high perfection semiconductor in such a manner that quantum interactions between different sites dictate the significant physics. Our current focus is on ‘artificial graphene’ (AG) in which a set of quantum dots (or sites) are patterned in a honeycomb lattice. The combination of leading edge nanofabrication with ultra-pure semiconductor materials in this project extends the frontier for small period, low-disorder AG systems, enabling the exploration of graphene physics in a semiconductor platform. TECHNICAL DESCRIPTION Contemporary condensed matter science has entered an era of discovery of new low-dimensional materials, such as graphene and other atomically thin materials, that exhibit exciting new physical phenomena that were previously inaccessible. Concurrent with the discovery and development of these new materials are impressive advancements in nanofabrication, which offer an ever-expanding toolbox for creating a myriad of high quality patterns at nanoscale dimensions. This project started about four years ago. Among its major achievements are the realizations of very small period artificial lattices with honeycomb topology in GaAs quantum wells. In our most recent work the periods of the ‘artificial graphene’ (AG) lattices extend down to 40 nm. These
Modelling high density phenomena in hydrogen fibre Z-pinches
International Nuclear Information System (INIS)
Chittenden, J.P.
1990-09-01
The application of hydrogen fibre Z-pinches to the study of the radiative collapse phenomenon is studied computationally. Two areas of difficulty, the formation of a fully ionized pinch from a cryogenic fibre and the processes leading to collapse termination, are addressed in detail. A zero-D model based on the energy equation highlights the importance of particle end losses and changes in the Coulomb logarithm upon collapse initiation and termination. A 1-D Lagrangian resistive MHD code shows the importance of the changing radial profile shapes, particularly in delaying collapse termination. A 1-D, three fluid MHD code is developed to model the ionization of the fibre by thermal conduction from a high temperature surface corona to the cold core. Rate equations for collisional ionization, 3-body recombination and equilibration are solved in tandem with fluid equations for the electrons, ions and neutrals. Continuum lowering is found to assist ionization at the corona-core interface. The high density plasma phenomena responsible for radiative collapse termination are identified as the self-trapping of radiation and free electron degeneracy. A radiation transport model and computational analogues for the effects of degeneracy upon the equation of state, transport coefficients and opacity are implemented in the 1-D, single fluid model. As opacity increases the emergent spectrum is observed to become increasingly Planckian and a fall off in radiative cooling at small radii and low frequencies occurs giving rise to collapse termination. Electron degeneracy terminates radiative collapse by supplementing the radial pressure gradient until the electromagnetic pinch force is balanced. Collapse termination is found to be a hybrid process of opacity and degeneracy effects across a wide range of line densities with opacity dominant at large line densities but with electron degeneracy becoming increasingly important at lower line densities. (author)
Transport phenomena in the human nasal cavity: a computational model.
Naftali, S; Schroter, R C; Shiner, R J; Elad, D
1998-01-01
Nasal inspiration is important for maintaining the internal milieu of the lung, since ambient air is conditioned to nearly alveolar conditions (body temperature and fully saturated with water vapor) on reaching the nasopharynx. We conducted a two-dimensional computational study of transport phenomena in model transverse cross sections of the nasal cavity of normal and diseased human noses for inspiration under various ambient conditions. The results suggest that during breathing via the normal human nose there is ample time for heat and water exchange to enable equilibration to near intraalveolar conditions. A normal nose can maintain this equilibrium under extreme environments (e.g., hot/humid, cold/dry, cold/humid). The turbinates increase the rate of local heat and moisture transport by narrowing the passageways for air and by induction of laminar swirls downstream of the turbinate wall. However, abnormal blood supply or mucous generation may reduce the rate of heat or moisture flux into the inspired air, and thereby affect the efficacy of the process.
Physical model of Nernst element
International Nuclear Information System (INIS)
Nakamura, Hiroaki; Ikeda, Kazuaki; Yamaguchi, Satarou
1998-08-01
Generation of electric power by the Nernst effect is a new application of a semiconductor. A key point of this proposal is to find materials with a high thermomagnetic figure-of-merit, which are called Nernst elements. In order to find candidates of the Nernst element, a physical model to describe its transport phenomena is needed. As the first model, we began with a parabolic two-band model in classical statistics. According to this model, we selected InSb as candidates of the Nernst element and measured their transport coefficients in magnetic fields up to 4 Tesla within a temperature region from 270 K to 330 K. In this region, we calculated transport coefficients numerically by our physical model. For InSb, experimental data are coincident with theoretical values in strong magnetic field. (author)
Modeling of Multi-Scale Channeling Phenomena in Porous Flow
Räss, Ludovic; Omlin, Samuel; Yarushina, Viktoriya; Simon, Nina; Podladchikov, Yuri
2015-04-01
Predictive modeling of fluid percolation through tight porous rocks is critical to evaluate environmental risks associated with waste storage and reservoir operations. To understand the evolution of two-phase mixtures of fluid and solid it is insufficient to only combine single-phase fluid flow methods and solid mechanics. A proper coupling of these two different multi-scales physical processes is required to describe the complex evolution of permeability and porosity in space and in time. We conduct numerical modeling experiments in geometrically simple but physically complex systems of stressed rocks containing self-focusing porous flow. Our model is physically and thermodynamically consistent and describes the formation and evolution of fluid pathways. The model consists of a system of coupled equations describing poro-elasto-viscous deformation and flow. Nonlinearity of the solid rheology is also taken into account. We have developed a numerical application based on an iterative finite difference scheme that runs on mutli-GPUs cluster in parallel. In order to validate these models, we consider the largest CO2 sequestration project in operation at the Sleipner field in the Norwegian North Sea. Attempts to match the observations at Sleipner using conventional reservoir simulations fail to capture first order observations, such as the seemingly effortless vertical flow of CO2 through low permeability shale layers and the formation of focused flow channels or chimneys. Conducted high-resolution three-dimensional numerical simulations predict the formation of dynamically evolving high porosity and permeability pathways as a natural outcome of porous flow nonlinearly coupled with rock deformation, which may trigger leakage through low permeability barriers.
International Nuclear Information System (INIS)
Ratta, G.A.; Vega, J.; Pereira, A.; Portas, A.; Luna, E. de la; Dormido-Canto, S.; Farias, G.; Dormido, R.; Sanchez, J.; Duro, N.; Vargas, H.; Santos, M.; Pajares, G.; Murari, A.
2008-01-01
Structural pattern recognition techniques allow the identification of plasma behaviours. Physical properties are encoded in the morphological structure of signals. Intelligent access methods have been applied to JET databases to retrieve data according to physical criteria. On the one hand, the structural form of signals has been used to develop general purpose data retrieval systems to search for both similar entire waveforms and similar structural shapes inside waveforms. On the other hand, domain dependent knowledge was added to the structural information of signals to create particular data retrieval methods for specific physical phenomena. The inclusion of explicit knowledge assists in data analysis. The latter has been applied in JET to look for first, cut-offs in ECE heterodyne radiometer signals and, second, L-H transitions
Energy Technology Data Exchange (ETDEWEB)
Ratta, G.A. [Asociacion EURATOM/CIEMAT para Fusion (Spain)], E-mail: giuseppe.ratta@ciemat.es; Vega, J.; Pereira, A.; Portas, A.; Luna, E. de la [Asociacion EURATOM/CIEMAT para Fusion (Spain); Dormido-Canto, S.; Farias, G.; Dormido, R.; Sanchez, J.; Duro, N.; Vargas, H. [Dpto. Informatica y Automatica-UNED, 28040 Madrid (Spain); Santos, M.; Pajares, G. [Dpto. Arquitectura de Computadores y Automatica-UCM, 28040 Madrid (Spain); Murari, A. [Consorzio RFX-Associazione EURATOM ENEA per la Fusione, Padua (Italy)
2008-04-15
Structural pattern recognition techniques allow the identification of plasma behaviours. Physical properties are encoded in the morphological structure of signals. Intelligent access methods have been applied to JET databases to retrieve data according to physical criteria. On the one hand, the structural form of signals has been used to develop general purpose data retrieval systems to search for both similar entire waveforms and similar structural shapes inside waveforms. On the other hand, domain dependent knowledge was added to the structural information of signals to create particular data retrieval methods for specific physical phenomena. The inclusion of explicit knowledge assists in data analysis. The latter has been applied in JET to look for first, cut-offs in ECE heterodyne radiometer signals and, second, L-H transitions.
Unraveling the physics of nanofluidic phenomena at the single-molecule level
Energy Technology Data Exchange (ETDEWEB)
Fornasiero, Francesco [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2015-10-13
Despite groundbreaking potential in a broad application space, several nanofluidic phenomena remain poorly understood. Toward advancing the understanding of fluid behavior under nanoscale confinement, we developed a novel, ideal platform for fundamental molecular transport studies, in which the fluidic channel is a single carbon nanotube (CNT). CNTs offer the advantage of simple chemistry and structure, which can be synthetically tuned with nanometer precision and accurately modeled. With combined experimental and computational approaches, we demonstrated that CNT pores with 1-5 nm diameters conduct giant ionic currents that follow an unusual sublinear electrolyte concentration dependence. The large magnitude of the ionic conductance appears to originate from a strong electro-osmotic flow in smooth CNT pores. First-principle simulations suggest that electro-osmotic flow arises from localized negative polarization charges on carbon atoms near a potassium (K^{+}) ion and from the strong cation-graphitic wall interactions, which drive K^{+} ions much closer to the wall than chlorides (Cl^{-}). Single-molecule translocation studies reveal that charged molecules may be distinguished from neutral species on the basis of the sign of the transient current change during their passage through the nanopore. Together with shedding light on a few controversial questions in the CNT nanofluidics area, these results may benefit LLNL’s Security Mission by providing the foundation for the development of advanced single-molecule detection system for bio/chem/explosive analytes. In addition, these experimental and computational platforms can be applied to advance fundamental knowledge in other fields, from energy storage and membrane separation to superfluid physics.
Modeling of deformation phenomena in volume label during its operation
Directory of Open Access Journals (Sweden)
Svitlana Sheludko
2017-06-01
Full Text Available BIt was considered in the article the research of physical and mechanical properties of materials based on PVC film ORACAL and RITRAMA that used in the production of volume labels. In particular, it was shown the changes of dependences between linear deformation of printed and unprinted films and the value of stress with regard to their minimum and maximum values. It was also established that deformation properties of the films are different in the transverse and longitudinal directions, which should be considered when producing labels. It was conducted the modeling of stress-strain state of volume label when gluing it to the surfaces of various shapes. We considered the boundary conditions for displacement and stress of labels layer components with regard to the chemical structure of epoxy resins and their physical and mechanical characteristics.
Natural Circulation Phenomena and Modelling for Advanced Water Cooled Reactors
International Nuclear Information System (INIS)
2012-03-01
The role of natural circulation in advanced water cooled reactor design has been extended with the adoption of passive safety systems. Some designs utilize natural circulation to remove core heat during normal operation. Most passive safety systems used in evolutionary and innovative water cooled reactor designs are driven by natural circulation. The use of passive systems based on natural circulation can eliminate the costs associated with the installation, maintenance and operation of active systems that require multiple pumps with independent and redundant electric power supplies. However, considering the weak driving forces of passive systems based on natural circulation, careful design and analysis methods must be employed to ensure that the systems perform their intended functions. Several IAEA Member States with advanced reactor development programmes are actively conducting investigations of natural circulation to support the development of advanced water cooled reactor designs with passive safety systems. To foster international collaboration on the enabling technology of passive systems that utilize natural circulation, in 2004 the IAEA initiated a coordinated research project (CRP) on Natural Circulation Phenomena, Modelling and Reliability of Passive Systems that Utilize Natural Circulation. Three reports were published within the framework of this CRP. The first report (IAEA-TECDOC-1474) contains the material developed for the first IAEA training course on natural circulation in water cooled nuclear power plants. The second report (IAEA-TECDOC-1624) describes passive safety systems in a wide range of advanced water cooled nuclear power plant designs, with the goal of gaining insights into system design, operation and reliability. This third, and last, report summarizes the research studies completed by participating institutes during the CRP period.
Numerical modeling transport phenomena in proton exchange membrane fuel cells
Suh, DongMyung
To study the coupled phenomena occurring in proton exchange membrane fuel cells, a two-phase, one-dimensional, non-isothermal model is developed in the chapter 1. The model includes water phase change, proton transport in the membrane and electro-osmotic effect. The thinnest, but most complex layer in the membrane electrode assembly, catalyst layer, is considered an interfacial boundary between the gas diffusion layer and the membrane. Mass and heat transfer and electro-chemical reaction through the catalyst layer are formulated into equations, which are applied to boundary conditions for the gas diffusion layer and the membrane. Detail accounts of the boundary equations and the numerical solving procedure used in this work are given. The polarization curve is calculated at different oxygen pressures and compared with the experimental results. When the operating condition is changed along the polarization curve, the change of physicochemical variables in the membrane electrode assembly is studied. In particular, the over-potential diagram presents the usage of the electrochemical energy at each layer of the membrane electrode assembly. Humidity in supplying gases is one of the most important factors to consider for improving the performance of PEMFE. Both high and low humidity conditions can result in a deteriorating cell performance. The effect of humidity on the cell performance is studied in the chapter 2. First, a numerical model based on computational fluid dynamics is developed. Second, the cell performances are simulated, when the relative humidity is changed from 0% to 100% in the anode and the cathode channel. The simulation results show how humidity in the reactant gases affects the water content distribution in the membrane, the over-potential at the catalyst layers and eventually the cell performance. In particular, the rapid enhancement in the cell performance caused by self-hydrating membrane is captured by the simulation. Fully humidifying either H2
Modelling of Electrodynamic Phenomena in Slowly Moving Media
Rozov, Andrey Leonidovich
2017-08-01
We discuss the feasibility of using, along with Minkowski equations obtained on the basis of the theory of relativity and used at present in electrodynamics, alternative methods of describing the processes of interaction between electromagnetic fields and moving media. In this article, a way of describing electromagnetic fields in terms of classical mechanics is offered. A system of electrodynamic equations for slowly moving media was derived on the basis of Maxwell's theory within the framework of classical mechanics using Wilsons' experimental data with dielectrics in a previous article [A. Rozov, Z. Naturforsch. 70, 1019 (2015)]. This article puts forward a physical model that explains the features of the derived equations. The offered model made it possible to suggest a new approach to the derivation of electrodynamic equations for slowly moving media. A variant of Galileo's relativity principle, in accordance with which the electrodynamic equations for slowly moving media should be considered as Galilean-invariant, is laid down on the basis of both the interpretation of Galileo's concept following from Galileo's works and Pauli's concept of postulate of relativity within the framework of the represented physical model.
Liben, Lynn S.; Golbeck, Susan L.
1984-01-01
Examines reasons for sex-related differences among adults on horizontality and verticality concepts. Studies the effects on task performance of inadequate knowlege of relevant physical phenomena and pictorial examples. (Author/AS)
Model Reduction and Coarse-Graining Approaches for Multiscale Phenomena
Gorban, Alexander N; Theodoropoulos, Constantinos; Kazantzis, Nikolaos K; Öttinger, Hans Christian
2006-01-01
Model reduction and coarse-graining are important in many areas of science and engineering. How does a system with many degrees of freedom become one with fewer? How can a reversible micro-description be adapted to the dissipative macroscopic model? These crucial questions, as well as many other related problems, are discussed in this book. Specific areas of study include dynamical systems, non-equilibrium statistical mechanics, kinetic theory, hydrodynamics and mechanics of continuous media, (bio)chemical kinetics, nonlinear dynamics, nonlinear control, nonlinear estimation, and particulate systems from various branches of engineering. The generic nature and the power of the pertinent conceptual, analytical and computational frameworks helps eliminate some of the traditional language barriers, which often unnecessarily impede scientific progress and the interaction of researchers between disciplines such as physics, chemistry, biology, applied mathematics and engineering. All contributions are authored by ex...
Proceedings of the Fifth Microgravity Fluid Physics and Transport Phenomena Conference
Singh, Bhim S. (Editor)
2000-01-01
The Fifth Microgravity Fluid Physics and Transport Phenomena Conference provided the scientific community the opportunity to view the current scope of the Microgravity Fluid Physics and Transport Phenomena Program and research opportunities and plans for the near future. Consistent with the conference theme "Microgravity Research an Agency-Wide Asset" the conference focused not only on fundamental research but also on applications of this knowledge towards enabling future space exploration missions. The conference included 14 invited plenary talks, 61 technical paper presentations, 61 poster presentations, exhibits and a forum on emerging research themes focusing on nanotechnology and biofluid mechanics. This web-based proceeding includes the presentation and poster charts provided by the presenters of technical papers and posters that were scanned at the conference site. Abstracts of all the papers and posters are included and linked to the presentations charts. The invited and plenary speakers were not required to provide their charts and are generally not available for scanning and hence not posted. The conference program is also included.
3D unified CFD to modeling of bubbles phenomena
International Nuclear Information System (INIS)
Vladimir V Chudanov; Anna E Aksenova; Valerii A Pervichko
2005-01-01
Full text of publication follows: During of the last ten years the developed numerical methods and algorithms for solving of heat and mass transfer problems in compressible/incompressible fluids were successfully tested at simulation of interaction of two immiscible liquids. Now these computing tools are extended on a case of two-phase flows, such as a liquids-gas system as follows: outside of bubbles the non-stationary incompressible Navier-Stokes equations in the primitive variables coupled with the heat transfer equation are used; inside of bubble a compressible medium model with low Mach limit is applied. To observe of an interface of liquid-gas system we use the modified level set method and three-dimensional advective schemes of TVD-type with small scheme diffusion with use of sub-grid simulation. These schemes with small diffusion were already applied by us under using of sub-grid simulation for interface transfer in case of two non-mixing liquids. For bubble phenomena a numerical technique based on the developed algorithms with a small scheme diffusion, for which the discrete approximations are constructed using the finite-volume methods and fully staggered grids is adapted. Testing of the developed approach is carried out on the set of test problems and a good agreement is obtained between numerical predictions and experimental data. The numerical technique was successfully utilized for numerical support of 3D experiment financed by Nuclear Energy Agency at the Organization economic cooperation and development within the framework of MASKA Project, where computational fluid dynamics of two non-mixing fluids such as corium and steel was investigated. In this paper there is application of developed approach for simulation of bubble flows, in particular, for study of coalescence of two drops. The developed technique has a high degree of efficiency and allows on a personal computer (3 GHz and 2 Gbytes RAM) to carry out CFD calculations on a grid with 10 7
PSI-BOIL, a building block towards the multi-scale modeling of flow boiling phenomena
International Nuclear Information System (INIS)
Niceno, Bojan; Andreani, Michele; Prasser, Horst-Michael
2008-01-01
Full text of publication follows: In these work we report the current status of the Swiss project Multi-scale Modeling Analysis (MSMA), jointly financed by PSI and Swissnuclear. The project aims at addressing the multi-scale (down to nano-scale) modelling of convective boiling phenomena, and the development of physically-based closure laws for the physical scales appropriate to the problem considered, to be used within Computational Fluid Dynamics (CFD) codes. The final goal is to construct a new computational tool, called Parallel Simulator of Boiling phenomena (PSI-BOIL) for the direct simulation of processes all the way down to the small-scales of interest and an improved CFD code for the mechanistic prediction of two-phase flow and heat transfer in the fuel rod bundle of a nuclear reactor. An improved understanding of the physics of boiling will be gained from the theoretical work as well as from novel small- and medium scale experiments targeted to assist the development of closure laws. PSI-BOIL is a computer program designed for efficient simulation of turbulent fluid flow and heat transfer phenomena in simple geometries. Turbulence is simulated directly (DNS) and its efficiency plays a vital role in a successful simulation. Having high performance as one of the main prerequisites, PSIBOIL is tailored in such a way to be as efficient a tool as possible, relying on well-established numerical techniques and sacrificing all the features which are not essential for the success of this project and which might slow down the solution procedure. The governing equations are discretized in space with orthogonal staggered finite volume method. Time discretization is performed with projection method, the most obvious a the most widely used choice for DNS. Systems of linearized equation, stemming from the discretization of governing equations, are solved with the Additive Correction Multigrid (ACM). methods. Two distinguished features of PSI-BOIL are the possibility to
Exploring large-scale phenomena in composite membranes through an efficient implicit-solvent model
Laradji, Mohamed; Kumar, P. B. Sunil; Spangler, Eric J.
2016-07-01
Several microscopic and mesoscale models have been introduced in the past to investigate various phenomena in lipid membranes. Most of these models account for the solvent explicitly. Since in a typical molecular dynamics simulation, the majority of particles belong to the solvent, much of the computational effort in these simulations is devoted for calculating forces between solvent particles. To overcome this problem, several implicit-solvent mesoscale models for lipid membranes have been proposed during the last few years. In the present article, we review an efficient coarse-grained implicit-solvent model we introduced earlier for studies of lipid membranes. In this model, lipid molecules are coarse-grained into short semi-flexible chains of beads with soft interactions. Through molecular dynamics simulations, the model is used to investigate the thermal, structural and elastic properties of lipid membranes. We will also review here few studies, based on this model, of the phase behavior of nanoscale liposomes, cytoskeleton-induced blebbing in lipid membranes, as well as nanoparticles wrapping and endocytosis by tensionless lipid membranes. Topical Review article submitted to the Journal of Physics D: Applied Physics, May 9, 2016
Richardson, John G.; Moore, Karen A.; Carrington, Robert A.
2006-04-25
A method and system for detecting, locating and quantifying a physical phenomena such as strain or a deformation in a structure. A plurality of laterally adjacent conductors may each include a plurality of segments. Each segment is constructed to exhibit a unit value representative of a defined energy transmission characteristic. A plurality of identity groups are defined with each identity group comprising a plurality of segments including at least one segment from each of the plurality of conductors. The segments contained within an identity group are configured and arranged such that each of their associated unit values may be represented by a concatenated digit string which is a unique number relative to the other identity groups. Additionally, the unit values of the segments within an identity group maintain unique ratios with respect to the other unit values in the identity group.
Pipeline including network and topology for identifying, locating and quantifying physical phenomena
Richardson, John G.; Moore, Karen A.; Carrington, Robert A.
2006-02-14
A method and system for detecting, locating and quantifying a physical phenomena such as strain or a deformation in a structure. A plurality of laterally adjacent conductors may each include a plurality of segments. Each segment is constructed to exhibit a unit value representative of a defined energy transmission characteristic. A plurality of identity groups are defined with each identity group comprising a plurality of segments including at least one segment from each of the plurality of conductors. The segments contained within an identity group are configured and arranged such that each of their associated unit values may be represented by a concatenated digit string which is a unique number relative to the other identity groups. Additionally, the unit values of the segments within an identity group maintain unique ratios with respect to the other unit values in the identity group.
Richardson, John G.; Moore, Karen A.; Carrington, Robert A.
2005-05-10
A method and system for detecting, locating and quantifying a physical phenomena such as strain or a deformation in a structure. A plurality of laterally adjacent conductors may each include a plurality of segments. Each segment is constructed to exhibit a unit value representative of a defined energy transmission characteristic. A plurality of identity groups are defined with each identity group comprising a plurality of segments including at least one segment from each of the plurality of conductors. The segments contained within an identity group are configured and arranged such that each of their associated unit values may be represented by a concatenated digit string which is a unique number relative to the other identity groups. Additionally, the unit values of the segments within an identity group maintain unique ratios with respect to the other unit values in the identity group.
Using LabVIEW for Applying Mathematical Models in Representing Phenomena
Faraco, G.; Gabriele, L.
2007-01-01
Simulations make it possible to explore physical and biological phenomena, where conducting the real experiment is impracticable or difficult. The implementation of a software program describing and simulating a given physical situation encourages the understanding of a phenomenon itself. Fifty-nine students, enrolled at the Mathematical Methods…
International Nuclear Information System (INIS)
Chela Flores, J.
1995-01-01
Our present understanding of the origin and evolution of chromosomes differs considerably from current understanding of the origin and evolution of the cell itself. Chromosome origins have been less prominent in research, as the emphasis has not shifted so far appreciably from the phenomenon of primeval nucleic acid encapsulation to that of the origin of gene organization, expression, and regulation. In this work we discuss some reasons why preliminary steps in this direction are being taken. We have been led to examine properties that have contributed to raise the ancestral prokaryotic programmes to a level where we can appreciate in eukaryotes a clear departure from earlier themes in the evolution of the cell from the last common ancestor. We shift our point of view from evolution of cell morphology to the point of view of the genes. In particular, we focus attention on possible physical bases for the way transmission of information has evolved in eukaryotes, namely, the inactivation of whole chromosomes. The special case of inactivation of the X chromosome in mammals is discussed, paying particular attention to the physical process of the spread of X inactivation in monotremes (platypus and echidna.) When experimental data is unavailable some theoretical analysis is possible based on the idea that in certain cases collective phenomena in genetics, rather than chemical detail, are better correlates of complex chemical processes. (author). Abstract only
International Nuclear Information System (INIS)
Chela Flores, J.
1995-08-01
Our present understanding of the origin and evolution of chromosomes differs considerably from current understanding of the origin and evolution of the cell itself. Chromosome origins have been less prominent in research, as the emphasis has not shifted so far appreciably from the phenomenon of primeval nucleic acid encapsulation to that of the origin of gene organization, expression, and regulation. In this work we discuss some reasons why preliminary steps in this direction are being taken. We have been led to examine properties that have contributed to raise the ancestral prokaryotic programmes to a level where we can appreciate in eukaryotes a clear departure from earlier themes in the evolution of cell from the last common ancestor. We shift our point of view from evolution of cell morphology to the point of view of the genes. In particular we focus attention on possible physical bases for the way transmission of information has evolved in eukaryotes, namely, the inactivation of whole chromosomes. The special case of the inactivation of the X chromosome in mammals is discussed, paying particular attention to the physical process of the spread of X inactivation in monotremes (platypus and echidna). When experimental data is unavailable some theoretical analysis is possible based on the idea that in certain cases collective phenomena in genetics, rather than chemical detail, are better correlates of complex chemical processes. (author). 65 refs
Fluid models and simulations of biological cell phenomena
Greenspan, H. P.
1982-01-01
The dynamics of coated droplets are examined within the context of biofluids. Of specific interest is the manner in which the shape of a droplet, the motion within it as well as that of aggregates of droplets can be controlled by the modulation of surface properties and the extent to which such fluid phenomena are an intrinsic part of cellular processes. From the standpoint of biology, an objective is to elucidate some of the general dynamical features that affect the disposition of an entire cell, cell colonies and tissues. Conventionally averaged field variables of continuum mechanics are used to describe the overall global effects which result from the myriad of small scale molecular interactions. An attempt is made to establish cause and effect relationships from correct dynamical laws of motion rather than by what may have been unnecessary invocation of metabolic or life processes. Several topics are discussed where there are strong analogies droplets and cells including: encapsulated droplets/cell membranes; droplet shape/cell shape; adhesion and spread of a droplet/cell motility and adhesion; and oams and multiphase flows/cell aggregates and tissues. Evidence is presented to show that certain concepts of continuum theory such as suface tension, surface free energy, contact angle, bending moments, etc. are relevant and applicable to the study of cell biology.
Modeling of transport phenomena in concrete porous media.
Plecas, Ilija
2014-02-01
Two fundamental concerns must be addressed when attempting to isolate low-level waste in a disposal facility on land. The first concern is isolating the waste from water, or hydrologic isolation. The second is preventing movement of the radionuclides out of the disposal facility, or radionuclide migration. Particularly, we have investigated here the latter modified scenario. To assess the safety for disposal of radioactive waste-concrete composition, the leakage of 60Co from a waste composite into a surrounding fluid has been studied. Leakage tests were carried out by the original method, developed at the Vinča Institute. Transport phenomena involved in the leaching of a radioactive material from a cement composite matrix are investigated using three methods based on theoretical equations. These are: the diffusion equation for a plane source: an equation for diffusion coupled to a first-order equation, and an empirical method employing a polynomial equation. The results presented in this paper are from a 25-y mortar and concrete testing project that will influence the design choices for radioactive waste packaging for a future Serbian radioactive waste disposal center.
Crises and Collective Socio-Economic Phenomena: Simple Models and Challenges
Bouchaud, Jean-Philippe
2013-05-01
Financial and economic history is strewn with bubbles and crashes, booms and busts, crises and upheavals of all sorts. Understanding the origin of these events is arguably one of the most important problems in economic theory. In this paper, we review recent efforts to include heterogeneities and interactions in models of decision. We argue that the so-called Random Field Ising model ( rfim) provides a unifying framework to account for many collective socio-economic phenomena that lead to sudden ruptures and crises. We discuss different models that can capture potentially destabilizing self-referential feedback loops, induced either by herding, i.e. reference to peers, or trending, i.e. reference to the past, and that account for some of the phenomenology missing in the standard models. We discuss some empirically testable predictions of these models, for example robust signatures of rfim-like herding effects, or the logarithmic decay of spatial correlations of voting patterns. One of the most striking result, inspired by statistical physics methods, is that Adam Smith's invisible hand can fail badly at solving simple coordination problems. We also insist on the issue of time-scales, that can be extremely long in some cases, and prevent socially optimal equilibria from being reached. As a theoretical challenge, the study of so-called "detailed-balance" violating decision rules is needed to decide whether conclusions based on current models (that all assume detailed-balance) are indeed robust and generic.
Identification of physical models
DEFF Research Database (Denmark)
Melgaard, Henrik
1994-01-01
The problem of identification of physical models is considered within the frame of stochastic differential equations. Methods for estimation of parameters of these continuous time models based on descrete time measurements are discussed. The important algorithms of a computer program for ML or MAP...... design of experiments, which is for instance the design of an input signal that are optimal according to a criterion based on the information provided by the experiment. Also model validation is discussed. An important verification of a physical model is to compare the physical characteristics...... of the model with the available prior knowledge. The methods for identification of physical models have been applied in two different case studies. One case is the identification of thermal dynamics of building components. The work is related to a CEC research project called PASSYS (Passive Solar Components...
Modelling supply networks and business cycles as unstable transport phenomena
Helbing, Dirk
2003-07-01
Physical concepts developed to describe instabilities in traffic flows can be generalized in a way that allows one to understand the well-known instability of supply chains (the so-called 'bull-whip effect'). That is, small variations in the consumption rate can cause large variations in the production rate of companies generating the requested product. Interestingly, the resulting oscillations have characteristic frequencies which are considerably lower than the variations in the consumption rate. This suggests that instabilities of supply chains may be the reason for the existence of business cycles. At the same time, we establish some links to queueing theory and between micro- and macroeconomics.
Analysing the Competency of Mathematical Modelling in Physics
Redish, Edward F.
2016-01-01
A primary goal of physics is to create mathematical models that allow both predictions and explanations of physical phenomena. We weave maths extensively into our physics instruction beginning in high school, and the level and complexity of the maths we draw on grows as our students progress through a physics curriculum. Despite much research on the learning of both physics and math, the problem of how to successfully teach most of our students to use maths in physics effectively remains unso...
Mathematical modeling of transport phenomena in porous SOFC anodes
Energy Technology Data Exchange (ETDEWEB)
Hussain, M.M.; Li, X. [Department of Mechanical Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Dincer, I. [Faculty of Engineering and Applied Science, University of Ontario Institute of Technology (UOIT) Oshawa, Ontario L1H 7K4 (Canada)
2007-01-15
In the present study, a mathematical model describing the transport of multi-component species inside porous SOFC anodes is developed. The model considers the reaction zone layer as a distinct volume rather than a mere mathematical surface (boundary condition) as treated in the existing models. The reaction zone layer is a relatively thin layer in the vicinity of electrolyte where electrochemical H{sub 2} oxidation takes place to produce electrons and water vapor. The model also incorporates the effect of Knudsen diffusion in the porous electrode and reaction zone layers. Simulations are performed using multi-component ethanol reformate fuel to predict the distribution of multi-component species in the electrode and reaction zone layers at different loads (current densities). In addition, the effect of shift reaction on the concentration over-potential is examined. Moreover, the effect of treating reaction zone layer as a discrete volume is investigated. (author)
Marriage of Electromagnetism and Gravity in an Extended Space Model and Astrophysical Phenomena
Andreev, V. A.; Tsipenyuk, D. Yu.
2013-09-01
The generalization of Einstein's special theory of relativity (SRT) is proposed. In this model the possibility of unification of scalar gravity and electromagnetism into a single unified field is considered. Formally, the generalization of the SRT is that instead of (1+3)-dimensional Minkowski space the (1+4)-dimensional extension G is considered. As a fifth additional coordinate the interval S is used. This value is saved under the usual Lorentz transformations in Minkowski space M, but it changes when the transformations in the extended space G are used. We call this model the extended space model (ESM). From a physical point of view our expansion means that processes in which the rest mass of the particles changes are acceptable now. If the rest mass of a particle does not change and the physical quantities do not depend on an additional variable S, then the electromagnetic and gravitational fields exist independently of each other. But if the rest mass is variable and there is a dependence on S, then these two fields are combined into a single unified field. In the extended space model a photon can have a nonzero mass and this mass can be either positive or negative. The gravitational effects such as the speed of escape, gravitational red shift and detection of light can be analyzed in the frame of the extended space model. In this model all these gravitational effects can be found algebraically by the rotations in the (1+4) dimensional space. Now it becomes possible to predict some future results of visible size of supermassive objects in our Universe due to new stage of experimental astronomy development in the RadioAstron Project and analyze phenomena is an explosion of the star V838 Mon.
Going Multi-viral: Synthedemic Modelling of Internet-based Spreading Phenomena
Directory of Open Access Journals (Sweden)
Marily Nika
2015-02-01
Full Text Available Epidemics of a biological and technological nature pervade modern life. For centuries, scientific research focused on biological epidemics, with simple compartmental epidemiological models emerging as the dominant explanatory paradigm. Yet there has been limited translation of this effort to explain internet-based spreading phenomena. Indeed, single-epidemic models are inadequate to explain the multimodal nature of complex phenomena. In this paper we propose a novel paradigm for modelling internet-based spreading phenomena based on the composition of multiple compartmental epidemiological models. Our approach is inspired by Fourier analysis, but rather than trigonometric wave forms, our components are compartmental epidemiological models. We show results on simulated multiple epidemic data, swine flu data and BitTorrent downloads of a popular music artist. Our technique can characterise these multimodal data sets utilising a parsimonous number of subepidemic models.
FDTD modelling of induced polarization phenomena in transient electromagnetics
Commer, Michael; Petrov, Peter V.; Newman, Gregory A.
2017-04-01
The finite-difference time-domain scheme is augmented in order to treat the modelling of transient electromagnetic signals containing induced polarization effects from 3-D distributions of polarizable media. Compared to the non-dispersive problem, the discrete dispersive Maxwell system contains costly convolution operators. Key components to our solution for highly digitized model meshes are Debye decomposition and composite memory variables. We revert to the popular Cole-Cole model of dispersion to describe the frequency-dependent behaviour of electrical conductivity. Its inversely Laplace-transformed Debye decomposition results in a series of time convolutions between electric field and exponential decay functions, with the latter reflecting each Debye constituents' individual relaxation time. These function types in the discrete-time convolution allow for their substitution by memory variables, annihilating the otherwise prohibitive computing demands. Numerical examples demonstrate the efficiency and practicality of our algorithm.
Calibrating emergent phenomena in stock markets with agent based models.
Fievet, Lucas; Sornette, Didier
2018-01-01
Since the 2008 financial crisis, agent-based models (ABMs), which account for out-of-equilibrium dynamics, heterogeneous preferences, time horizons and strategies, have often been envisioned as the new frontier that could revolutionise and displace the more standard models and tools in economics. However, their adoption and generalisation is drastically hindered by the absence of general reliable operational calibration methods. Here, we start with a different calibration angle that qualifies an ABM for its ability to achieve abnormal trading performance with respect to the buy-and-hold strategy when fed with real financial data. Starting from the common definition of standard minority and majority agents with binary strategies, we prove their equivalence to optimal decision trees. This efficient representation allows us to exhaustively test all meaningful single agent models for their potential anomalous investment performance, which we apply to the NASDAQ Composite index over the last 20 years. We uncover large significant predictive power, with anomalous Sharpe ratio and directional accuracy, in particular during the dotcom bubble and crash and the 2008 financial crisis. A principal component analysis reveals transient convergence between the anomalous minority and majority models. A novel combination of the optimal single-agent models of both classes into a two-agents model leads to remarkable superior investment performance, especially during the periods of bubbles and crashes. Our design opens the field of ABMs to construct novel types of advanced warning systems of market crises, based on the emergent collective intelligence of ABMs built on carefully designed optimal decision trees that can be reversed engineered from real financial data.
Calibrating emergent phenomena in stock markets with agent based models
Sornette, Didier
2018-01-01
Since the 2008 financial crisis, agent-based models (ABMs), which account for out-of-equilibrium dynamics, heterogeneous preferences, time horizons and strategies, have often been envisioned as the new frontier that could revolutionise and displace the more standard models and tools in economics. However, their adoption and generalisation is drastically hindered by the absence of general reliable operational calibration methods. Here, we start with a different calibration angle that qualifies an ABM for its ability to achieve abnormal trading performance with respect to the buy-and-hold strategy when fed with real financial data. Starting from the common definition of standard minority and majority agents with binary strategies, we prove their equivalence to optimal decision trees. This efficient representation allows us to exhaustively test all meaningful single agent models for their potential anomalous investment performance, which we apply to the NASDAQ Composite index over the last 20 years. We uncover large significant predictive power, with anomalous Sharpe ratio and directional accuracy, in particular during the dotcom bubble and crash and the 2008 financial crisis. A principal component analysis reveals transient convergence between the anomalous minority and majority models. A novel combination of the optimal single-agent models of both classes into a two-agents model leads to remarkable superior investment performance, especially during the periods of bubbles and crashes. Our design opens the field of ABMs to construct novel types of advanced warning systems of market crises, based on the emergent collective intelligence of ABMs built on carefully designed optimal decision trees that can be reversed engineered from real financial data. PMID:29499049
Vacuum spark breakdown model based on exploding metal wire phenomena
International Nuclear Information System (INIS)
Haaland, J.
1984-06-01
Spark source mass spectra (SSMS) indicates that ions are extracted from an expanding and decaying plasma. The intensity distribution shows no dependance on vaporization properties of individual elements which indicates explosive vapour formation. This seems further to be a requirement for bridging a vacuum gap. A model including plasma ejection from a superheated anode spot by a process similar to that of an exploding metal wire is proposed. The appearance of hot plasma points in low inductance vacuum sparks can then be explained as exploding micro particles ejected from a final central anode spot. The phenomenological model is compared with available experimental results from literature, but no extensive quantification is attempted
Air flow phenomena in the model of the blind drift
Directory of Open Access Journals (Sweden)
Jaszczur Marek
2016-01-01
Full Text Available In the presented paper, Particle Image Velocimetry (PIV has been used to investigate flow pattern and turbulent structure in the model of blind drift. The presented model exist in mining, and has been analyzed to resolve ventilation issues. Blind region is particularly susceptible to unsafe methane accumulation. The measurement system allows us to evaluate all components of the velocity vector in channel cross-section simultaneously. First order and second order statistic of the velocity fields from different channel cross-section are computed and analyzed.
Modelling toluene oxidation : Incorporation of mass transfer phenomena
Hoorn, J.A.A.; van Soolingen, J.; Versteeg, G. F.
The kinetics of the oxidation of toluene have been studied in close interaction with the gas-liquid mass transfer occurring in the reactor. Kinetic parameters for a simple model have been estimated on basis of experimental observations performed under industrial conditions. The conclusions for the
Searches for phenomena beyond the Standard Model at the Large ...
Indian Academy of Sciences (India)
metry searches at the LHC is thus the channel with large missing transverse momentum and jets of high transverse momentum. No excess above the expected SM background is observed and limits are set on supersymmetric models. Figures 1 and 2 show the limits from ATLAS [11] and CMS [12]. In addition to setting limits ...
Modelling of Transport Phenomena at Cement Matrix—Aggregate Interfaces
DEFF Research Database (Denmark)
van Breugel, Klaas; Koenders, Eddie; Ye, Guang
2004-01-01
The performance of a heterogeneous material like concrete is largely determined by the many interfaces in this material. This contribution focuses on the potential of numerical simulation models to investigate the character of the matrix-aggregate interfacial zone and to simulate hydration-induce...
International Nuclear Information System (INIS)
Garcia L, Carlos Eduardo; Hurtado G, Jorge Eduardo
2003-01-01
Upon considering the vulnerability of a urban system in a holistic way and taking into account some natural, technological and social factors, a model based upon a system of fuzzy logic, allowing to estimate the vulnerability of any system under natural phenomena potentially catastrophic is proposed. The model incorporates quantitative and qualitative variables in a dynamic system, in which variations in one of them have a positive or negative impact over the rest. An urban system model and an indicator model to determine the vulnerability due to natural phenomena were designed
Two-fluid modeling of thermal-hydraulic phenomena for best-estimate LWR safety analysis
International Nuclear Information System (INIS)
Yadigaroglu, G.; Andreani, M.
1989-01-01
Two-fluid formulation of the conservation equations has allowed modelling of the two-phase flow and heat transfer phenomena and situations involving strong departures in thermal and velocity equilibrium between the phases. The paper reviews the state of the art in modelling critical flows, and certain phase separation phenomena, as well as post-dryout heat transfer situations. Although the two-fluid models and the codes have the potential for correctly modelling such situations, this potential has not always been fully used in practice. (orig.)
Elementary particle physics and high energy phenomena. Progress report for FY93
Energy Technology Data Exchange (ETDEWEB)
Barker, A.R.; Cumalat, J.P.; De Alwis, S.P.; DeGrand, T.A.; Ford, W.T.; Mahanthappa, K.T.; Nauenberg, U.; Rankin, P.; Smith, J.G.
1992-06-01
Experimental and theoretical high-energy physics programs at the University of Colorado are reported. Areas of concentration include the following: study of the properties of the Z{sup 0} with the SLD detector; fixed-target K-decay experiments; the R&D program for the muon system: the SDC detector; high-energy photoproduction of states containing heavy quarks; electron--positron physics with the CLEO II detector at CESR; lattice QCD; and spin models and dynamically triangulated random surfaces. 24 figs., 2 tabs., 117 refs.
Modeling of transport phenomena in tokamak plasmas with neural networks
Energy Technology Data Exchange (ETDEWEB)
Meneghini, O., E-mail: meneghini@fusion.gat.com [Oak Ridge Associated Universities, 120 Badger Ave, Oak Ridge, Tennessee 37830 (United States); Luna, C. J. [Arizona State University, 411 N. Central Ave, Phoenix, Arizona 85004 (United States); Smith, S. P.; Lao, L. L. [General Atomics, San Diego, California 92186-5608 (United States)
2014-06-15
A new transport model that uses neural networks (NNs) to yield electron and ion heat flux profiles has been developed. Given a set of local dimensionless plasma parameters similar to the ones that the highest fidelity models use, the NN model is able to efficiently and accurately predict the ion and electron heat transport profiles. As a benchmark, a NN was built, trained, and tested on data from the 2012 and 2013 DIII-D experimental campaigns. It is found that NN can capture the experimental behavior over the majority of the plasma radius and across a broad range of plasma regimes. Although each radial location is calculated independently from the others, the heat flux profiles are smooth, suggesting that the solution found by the NN is a smooth function of the local input parameters. This result supports the evidence of a well-defined, non-stochastic relationship between the input parameters and the experimentally measured transport fluxes. The numerical efficiency of this method, requiring only a few CPU-μs per data point, makes it ideal for scenario development simulations and real-time plasma control.
Mass segregation phenomena using the Hamiltonian Mean Field model
Steiner, J. R.; Zolacir, T. O.
2018-02-01
Mass segregation problem is thought to be entangled with the dynamical evolution of young stellar clusters (Olczak, 2011 [1]). This is a common sense in the astrophysical community. In this work, the Hamiltonian Mean Field (HMF) model with different masses is studied. A mass segregation phenomenon (MSP) arises from this study as a dynamical feature. The MSP in the HMF model is a consequence of the Landau damping (LD) and it appears in systems that the interactions belongs to a long range regime. Actually HMF is a toy model known to show up the main characteristics of astrophysical systems due to the mean field character of the potential and for different masses, as stellar and galaxies clusters, also exhibits MSP. It is in this sense that computational simulations focusing in what happens over the mass distribution in the phase space are performed for this system. What happens through the violent relaxation period and what stands for the quasi-stationary states (QSS) of this dynamics is analyzed. The results obtained support the fact that MSP is observed already in the violent relaxation time and is maintained during the QSS. Some structures in the mass distribution function are observed. As a result of this study the mass distribution is determined by the system dynamics and is independent of the dimensionality of the system. MSP occurs in a one dimensional system as a result of the long range forces that acts in the system. In this approach MSP emerges as a dynamical feature. We also show that for HMF with different masses, the dynamical time scale is N.
Fine numerical modelling of thermohydraulic phenomena in EDF PWR reactors
International Nuclear Information System (INIS)
Boulot, F.
1993-01-01
Over the last 20 years, EDF has developed a family of 2D and 3D industrial thermohydraulics software to solve problems encountered in existing PWR power plants and to design new reactors for the future. The equations used in the models are the averaged Navier-Stokes and energy equations. A brief description is given of the four main codes developed for single-phase and two-phase water-steam flows, some of which use finite differences or finite volumes methods, while others make use of finite elements methods. An example of application is given for each code. (author). 4 figs., 4 refs
Silva, J. N.; Voelzke, M. R.; Araújo, M. S. T.
2018-03-01
Although Astronomy is part of everyday life of the people, peculiarities are little-known for an observer on the equator, as residents in Macapá-AP, located at Latitude Zero. So, this work aims to support physics teaching focusing on the correct diffusion of some physical phenomena which have an intrinsic relationship with Astronomy from the sight of an observer at latitude zero, highlighting the celestial sphere visualization and emphasizing which constellations are visible during an earth year, being proposed the elaboration of a planisphere to this latitude. It's also discussed about the Solstices and, more specifically, about the Equinoxes and their particularities for an observer in latitude zero. The offered approach can help teachers of Physics and Science who work in regular education schools to explore these important astronomical phenomena.
La cultura física y el deporte: fenómenos sociales /Physical culture and sport: social phenomena
Directory of Open Access Journals (Sweden)
Diana A. Camargo R
2013-08-01
Full Text Available La cultura física y el deporte son categorías que se han relacionado con la actividad física y la educación física a lo largo del tiempo, retomando diferentes paradigmas de conocimiento; sin embargo, el paradigma imperante ha sido el empírico-analítico, que reduce la mirada a los fenómenos medibles y observables. Objetivo: identificar las concepciones y enfoques de la cultura física y el deporte en los diferentes momentos de la historia, planteados desde la lógica del modelo de la determinación social propio de la epidemiología crítica. Metodología: revisión sistemática que permite reconocer los conceptos, teorías y modelos planteados nacional e internacionalmente alrededor de las categorías cultura física y deporte, tomando como modelo de análisis la determinación social. Resultados: la cultura física es un concepto relacionado con el cuerpo, la cultura y el movimiento que no se reconoce en las bases de datos; por el contrario, se relaciona con términos de búsqueda como deporte, recreación y actividad física. No obstante, en algunos países la cultura física se considera como un conjunto de programas y acciones desarrollados desde las áreas del deporte, la recreación y la actividad física, la cual se incluye dentro de las políticas públicas y planes de gobierno. Discusión: en Colombia no hay claridad sobre el significado y la implementación de la cultura física, por esto, se hace necesario revisar este concepto, el cual se ha utilizado dentro los procesos de formación de los profesionales de cultura física, el deporte y la recreación. -- Physical culture and sport are categories that have been associated with physical activity and physical education throughout time while picking up different paradigms of knowledge. However, the prevailing paradigm has been the empirical and analytical view, which focuses only on measurable and observable phenomena. Objective: to identify the concepts and approaches
DEFF Research Database (Denmark)
Kneubil, Fabiana Botelho
2016-01-01
In this work we show an approach based on models, for an usual subject in an introductory physics course, in order to foster discussions on the nature of physical knowledge. The introduction of elements of the nature of knowledge in physics lessons has been emphasised by many educators and one uses...... the case of metals to show the theoretical and phenomenological dimensions of physics. The discussion is made by means of four questions whose answers cannot be reached neither for theoretical elements nor experimental measurements. Between these two dimensions it is necessary to realise a series...... of reasoning steps to deepen the comprehension of microscopic concepts, such as electrical resistivity, drift velocity and free electrons. When this approach is highlighted, beyond the physical content, aspects of its nature become explicit and may improve the structuring of knowledge for learners...
Aguilar-Marín, Pablo; Chavez-Bacilio, Mario; Jáuregui-Rosas, Segundo
2018-05-01
Tracker is a piece of freeware software, designed to use video recorded images of the motion of objects as input data, and has been mostly applied in physics education to analyse and simulate physical phenomena in mechanics. In this work we report the application of Tracker to the study of experiments in electricity and magnetism using analog instruments for electrical signal measurements. As we are unable to directly video-track the motion of electrons in electric circuits, the angular deflections of the instruments’ pointers were video captured instead. The kinematic variables (angular position as a function of time) had to be related to the electrical ones (voltages and currents as a function of time). Two well-known experiments in physics teaching, the RC circuit for charging and discharging a capacitor and Faraday electromagnetic induction, were chosen to illustrate the procedures. The third experiment analysed and modeled with Tracker was the rather well-known electromagnetic retardation of disk- or cylinder-shaped magnets falling inside non-magnetic metallic pipes. Instead of metallic pipes we used an aluminum plate with an arrangement of a couple of parallelepiped-shaped magnets falling parallel to the plate. In the three cases studied, the experimental and the Tracker simulation results were in very good agreement. These outcomes show that it is possible to exploit the potential of Tracker software in areas other than mechanics, in areas where electrical signals are involved. The experiments are inexpensive and simple to perform, and are suitable for high school and introductory undergraduate courses in electricity, magnetism and electronics. We propose the use of Tracker combined with analog measuring devices to explore further its applications in electricity, magnetism, electronics and in other experimental sciences where electrical signals are involved.
Bi-frequency pendulum on a rotary platform: modeling various optical phenomena
International Nuclear Information System (INIS)
Zel'dovich, Boris Ya; Soileau, Marion J
2004-01-01
The teaching of optical phenomena can be enhanced through the use of analogies to the motion of a bi-freguency pendulum. In this text we target demonstrations to four groups of students and scientists: younger schoolchildren to high school seniors; 7th graders to college juniors; college juniors to final-year graduate students in physics, optics and engineering; and college seniors to research scientists. The main defference between the groups is in the level of mathematics required to make the analogy to optical phenomena. Most of the physical ideas may be understood and appreciated even in junior high school and serve as a motivation for deeper study of mathematics and science. (methodological notes)
Kaptein, Maurits; Van Emden, Robin; Iannuzzi, Davide
2017-01-01
Due to the ubiquitous presence of treatment heterogeneity, measurement error, and contextual confounders, numerous social phenomena are hard to study. Precise control of treatment variables and possible confounders is often key to the success of studies in the social sciences, yet often proves out
Kaptein, M.C.; Emden, R. van; Iannuzzi, D.
2017-01-01
Due to the ubiquitous presence of treatment heterogeneity, measurement error, and contextual confounders, numerous social phenomena are hard to study. Precise control of treatment variables and possible confounders is often key to the success of studies in the social sciences, yet often proves out
Energy Technology Data Exchange (ETDEWEB)
Bellantoni, L.
2009-11-01
There are many recent results from searches for fundamental new physics using the TeVatron, the SLAC b-factory and HERA. This talk quickly reviewed searches for pair-produced stop, for gauge-mediated SUSY breaking, for Higgs bosons in the MSSM and NMSSM models, for leptoquarks, and v-hadrons. There is a SUSY model which accommodates the recent astrophysical experimental results that suggest that dark matter annihilation is occurring in the center of our galaxy, and a relevant experimental result. Finally, model-independent searches at D0, CDF, and H1 are discussed.
Directory of Open Access Journals (Sweden)
Dongkyoung Lee
2018-02-01
Full Text Available Lithium-ion batteries have a higher energy density than other secondary batteries. Among the lithium-ion battery manufacturing process, electrode cutting is one of the most important processes since poor cut quality leads to performance degradation, separator protrusion, and local electric stress concentration. This may, eventually, lead to malfunction of lithium-ion batteries or explosion. The current mechanical cutting technology uses a contact process and this may lead to process instability. Furthermore, there are additional costs if the tools and cell design are changed. To solve these issues, laser cutting has been used. Conventional dependent parameters have limitations in investigating and explaining many physical phenomena during the laser cutting of electrodes. Therefore, this study proposes specific widths such as melting, top, and kerf width. Moreover, the relationship between laser parameters and multiphysical phenomena with the proposed widths are investigated. Five types of classification with regard to physical phenomena are presented and explained with SEM images. Cutting efficiency is estimated with the proposed widths. The proposed specific cutting widths, five types of geometrical classification, and cutting efficiency can be used as standardized parameters to evaluate the cutting quality.
Numerical modelling of tools steel hardening. A thermal phenomena and phase transformations
Directory of Open Access Journals (Sweden)
T. Domański
2010-01-01
Full Text Available This paper the model hardening of tool steel takes into considerations of thermal phenomena and phase transformations in the solid state are presented. In the modelling of thermal phenomena the heat equations transfer has been solved by Finite Elements Method. The graph of continuous heating (CHT and continuous cooling (CCT considered steel are used in the model of phase transformations. Phase altered fractions during the continuous heating austenite and continuous cooling pearlite or bainite are marked in the model by formula Johnson-Mehl and Avrami. For rate of heating >100 K/s the modified equation Koistinen and Marburger is used. Modified equation Koistinen and Marburger identify the forming fraction of martensite.
Analysis and modeling of coupled thermo-hydro-mechanical phenomena in 3D fractured media
International Nuclear Information System (INIS)
Canamon Valera, I.
2006-11-01
This doctoral research was conducted as part of a joint France-Spain co-tutelage PhD thesis in the framework of a bilateral agreement between two universities, the Institut National Polytechnique de Toulouse (INPT) and the Universidad Politecnica de Madrid (UPM). It concerns a problem of common interest at the national and international levels, namely, the disposal of radioactive waste in deep geological repositories. The present work is devoted, more precisely, to near-field hydrogeological aspects involving mass and heat transport phenomena. The first part of the work is devoted to a specific data interpretation problem (pressures, relative humidities, temperatures) in a multi-barrier experimental system at the scale of a few meters - the 'Mock-Up Test' of the FEBEX project, conducted in Spain. Over 500 time series are characterized in terms of spatial, temporal, and/or frequency/scale-based statistical analysis techniques. The time evolution and coupling of physical phenomena during the experiment are analyzed, and conclusions are drawn concerning the behavior and reliability of the sensors. The second part of the thesis develops in more detail the 3-Dimensional (3D) modeling of coupled Thermo-Hydro-Mechanical phenomena in a fractured porous rock, this time at the scale of a hundred meters, based on the data of the 'In-Situ Test' of the FEBEX project conducted at the Grimsel Test Site in the Swiss Alps. As a first step, a reconstruction of the 3D fracture network is obtained by Monte Carlo simulation, taking into account through optimization the geomorphological data collected around the FEBEX gallery. The heterogeneous distribution of traces observed on the cylindrical wall of the tunnel is fairly well reproduced in the simulated network. In a second step, we develop a method to estimate the equivalent permeability of a many-fractured block by extending the superposition method of Ababou et al. [1994] to the case where the permeability of the rock matrix is not
Directory of Open Access Journals (Sweden)
Cándido Manuel GARCÍA CRUZ
2016-06-01
Full Text Available An unabridged translation of a work of Nicolas Lémery (1645–1715 is presented for the first time in Spanish, wherein this French chemist and apothecary attempts an explanation on physical and chemical basis of several significant phenomena in Earth Sciences, such as earthquakes, subterranean fires, hurricanes, lightning and thunder. This explanation had a common cause for all the aforementioned phenomena: the processes of mineral fermentation, in this case of sulfur and iron, as a heat source, within the corpuscular theory of matter and mechanistic philosophy, and likewise it represents an interesting contribution of the influence of chemistry on the incipient development of experimental geology at the dawn of the 18th Century.
Anomalous transport phenomena in Weyl metal beyond the Drude model for Landau's Fermi liquids.
Kim, Ki-Seok; Kim, Heon-Jung; Sasaki, M; Wang, J-F; Li, L
2014-12-01
Landau's Fermi-liquid theory is the standard model for metals, characterized by the existence of electron quasiparticles near a Fermi surface as long as Landau's interaction parameters lie below critical values for instabilities. Recently this fundamental paradigm has been challenged by the physics of strong spin-orbit coupling, although the concept of electron quasiparticles remains valid near the Fermi surface, where Landau's Fermi-liquid theory fails to describe the electromagnetic properties of this novel metallic state, referred to as Weyl metal. A novel ingredient is that such a Fermi surface encloses a Weyl point with definite chirality, referred to as a chiral Fermi surface, which can arise from breaking of either time reversal or inversion symmetry in systems with strong spin-orbit coupling, responsible for both the Berry curvature and the chiral anomaly. As a result, electromagnetic properties of the Weyl metallic state are described not by conventional Maxwell equations but by axion electrodynamics, where Maxwell equations are modified with a topological-in-origin spatially modulated [Formula: see text] term. This novel metallic state was realized recently in Bi[Formula: see text]Sb x around [Formula: see text] under magnetic fields, where the Dirac spectrum appears around the critical point between the normal semiconducting ([Formula: see text]) and topological semiconducting phases ([Formula: see text]) and the time reversal symmetry breaking perturbation causes the Dirac point to split into a pair of Weyl points along the direction of the applied magnetic field for a very strong spin-orbit coupled system. In this review article, we discuss how the topological structure of both the Berry curvature and the chiral anomaly (axion electrodynamics) gives rise to anomalous transport phenomena in [Formula: see text]Sb x around [Formula: see text] under magnetic fields, thus modifying the Drude model of Landau's Fermi liquids.
Scale breaking effects in the quark-parton model for large P perpendicular phenomena
International Nuclear Information System (INIS)
Baier, R.; Petersson, B.
1977-01-01
We discuss how the scaling violations suggested by an asymptotically free parton model, i.e., the Q 2 -dependence of the transverse momentum of partons within hadrons may affect the parton model description of large p perpendicular phenomena. We show that such a mechanism can provide an explanation for the magnitude of the opposite side correlations and their dependence on the trigger momentum. (author)
Computational Modelling of a Tangentially Fired Boiler With Deposit Formation Phenomena
Modliński Norbert J.
2014-01-01
Any complete CFD model of pulverised coal-fired boiler needs to consider ash deposition phenomena. Wall boundary conditions (temperature and emissivity) should be temporally corrected to account for the effects of deposit growth on the combustion conditions. At present voluminous publications concerning ash related problems are available. The current paper presents development of an engineering tool integrating deposit formation models with the CFD code. It was then applied to two tangentiall...
Modelling of CRUD growth phenomena on PWR fuel rods under nucleate boiling conditions
International Nuclear Information System (INIS)
Ferrer, A.; Dacquait, F.; Gall, B.; Ranchoux, G.; Riot, G.
2012-09-01
PWR primary circuit materials undergo general corrosion leading to a release of metallic element release and subsequent process of particle deposition and ion precipitation on the primary circuit surfaces. The species accumulated on fuel rods are activated by neutron flux. Consequently, crud erosion and dissolution induce primary coolant contamination. In French PWRs, 58 Co volume activity is generally low and almost constant (< 30 MBq.m -3 ) throughout an ordinary operating cycle. In some specific cases, a significant increase in volume activity is observed after the middle of a cycle (100-1000 MBq.m -3 for 58 Co) when conditions for nucleate boiling are locally reached in certain fuel assemblies. Indeed, it is well known that nucleate boiling intensifies the deposition process. The thickness of the crud layer can reach some micrometers in non-boiling areas, whereas it can reach 100 micrometers in boiling areas. Crud growth in boiling conditions can be related to three phenomena: bubble growth induces deposition process (called boiling deposition), bubbles induce concentration increase at crud-coolant interface (called enrichment and modelled by the enrichment factor, the ratio between the wall concentration and the bulk concentration) and vaporisation induces concentration increase inside the crud. A literature review on the modelling of these phenomena and on the crud structure in nucleate boiling conditions has been carried out. The OSCAR [1] calculation code developed by the CEA to predict surface and volume activities in a single phase PWR primary circuit was chosen as a basis for present study. Ability to describe local nucleate boiling conditions was added to this code leading to realistic modelling of subsequent volume activity increase. In this article, we present the results obtained using a modified version of the OSCAR PC V1.2 calculation code including: - A double phase thermal-hydraulic module, - A model of boiling crud growth, able to calculate
3D numerical modeling of coupled phenomena in induced processes of heat treatment with malice
Directory of Open Access Journals (Sweden)
Triwong Peeteenut
2008-01-01
Full Text Available This paper describes a multi-method Malice package for three dimension coupled phenomena in induced processes of heat treatment by an algorithm weakly coupled with the Migen package integral method defining the electromagnetic model and the Flux-Expert package finite element method defining the thermal model. The integral method is well suited to inductive systems undergoing sinusoidal excitation at midrange or high frequency. The unknowns of both models are current density, scalar potential and temperature. Joule power in the electromagnetic model is generated by Eddy currents. It becomes the heat source in the thermal model.
How would photons describe natural phenomena based upon their physical experiences?
Roychoudhuri, Chandrasekhar
2013-10-01
The question posed in the title represents an impossible approach to scientific investigation, but the approach is like a subjectivist. Obviously, photons cannot express their views; neither can we ask directly any scientific questions to the photons. The purpose is to draw the attention of the reader that even our strongly mathematically driven scientific enterprise is full of subjectivism when we start dissecting our thinking process. First, we frame questions in our mind to understand a natural phenomenon we have been observing. Let us not forget that framing the question determine the answer. The answers guide us to frame the foundational hypotheses to build a theory to "explain" the phenomenon under study. Our mind is a product of biological evolutionary requirements; which is further re-programmed by strong human social cultures. In other words, human constructed theories cannot spontaneously become rigorously objective, unless we consciously make them so. We need to develop a methodology of scientific thinking that will automatically force us to make repeated iterative corrections in generating questions as objectively as possible. Those questions will then guide us to re-construct the foundational hypotheses and re-frame the working theories. We are proposing that we add Interaction Process Mapping Epistemology (IPM-E) as a necessary extra thinking tool; which will complement the prevailing Measurable Data Modeling Epistemology (MDM-E). We believe that ongoing interaction processes in nature represent reality ontology. So the iterative application of IPM-E, along with MDM-E, will keep us along the route of ontological reality. We apply this prescription to reveal the universal property, Non-Interaction of Waves, which we have been neglecting for centuries. Using this property, we demonstrate that a large number of ad hoc hypotheses from Classical-, QM-, Relativity- and Astro-Physics can be easily modified to make physics more causal and understandable
Discussion of heat transfer phenomena in fluids at supercritical pressure with the aid of CFD models
International Nuclear Information System (INIS)
Sharabi, Medhat; Ambrosini, Walter
2009-01-01
The paper discusses heat transfer enhancement and deterioration phenomena observed in experimental data for fluids at supercritical pressure. The results obtained by the application of various CFD turbulence models in the prediction of experimental data for water and carbon dioxide flowing in circular tubes are firstly described. On this basis, the capabilities of the addressed models in predicting the observed phenomena are shortly discussed. Then, the analysis focuses on further results obtained by a low-Reynolds number k - ε model addressing one of the considered experimental apparatuses by changing the operating conditions. In particular, the usual imposed heat flux boundary condition is changed to assigned wall temperature, in order to highlight effects otherwise impossible to point out. The obtained results, supported by considerations drawn from experimental information, allow comparing the trends observed for heat transfer deterioration at supercritical pressure with those typical of the thermal crisis in boiling systems, clarifying old concepts of similarity among them
Duives, Dorine C.; Daamen, Winnie; Hoogendoorn, Serge P.
2016-04-01
In recent years numerous pedestrian simulation tools have been developed that can support crowd managers and government officials in their tasks. New technologies to monitor pedestrian flows are in dire need of models that allow for rapid state-estimation. Many contemporary pedestrian simulation tools model the movements of pedestrians at a microscopic level, which does not provide an exact solution. Macroscopic models capture the fundamental characteristics of the traffic state at a more aggregate level, and generally have a closed form solution which is necessary for rapid state estimation for traffic management purposes. This contribution presents a next step in the calibration and validation of the macroscopic continuum model detailed in Hoogendoorn et al. (2014). The influence of global and local route choice on the development of crowd movement phenomena, such as dissipation, lane-formation and stripe-formation, is studied. This study shows that most self-organization phenomena and behavioural trends only develop under very specific conditions, and as such can only be simulated using specific parameter sets. Moreover, all crowd movement phenomena can be reproduced by means of the continuum model using one parameter set. This study concludes that the incorporation of local route choice behaviour and the balancing of the aptitude of pedestrians with respect to their own class and other classes are both essential in the correct prediction of crowd movement dynamics.
Hafner, Robert; Stewart, Jim
Past problem-solving research has provided a basis for helping students structure their knowledge and apply appropriate problem-solving strategies to solve problems for which their knowledge (or mental models) of scientific phenomena is adequate (model-using problem solving). This research examines how problem solving in the domain of Mendelian genetics proceeds in situations where solvers' mental models are insufficient to solve problems at hand (model-revising problem solving). Such situations require solvers to use existing models to recognize anomalous data and to revise those models to accommodate the data. The study was conducted in the context of 9-week high school genetics course and addressed: the heuristics charactenstic of successful model-revising problem solving: the nature of the model revisions, made by students as well as the nature of model development across problem types; and the basis upon which solvers decide that a revised model is sufficient (that t has both predictive and explanatory power).
Lee, C. T.; Lee, C. C.
2015-04-01
This paper introduces a systematic approach to investigate a higher order nonlinear dispersive wave equation for modeling different wave modes. We present both the conventional KdV-type soliton and anomaly type solitons for the equation. We also show the conservation laws and Hamiltonian structures for the equation. Our results suggest that the underlying equation has more interacting soliton phenomena than one would have known for the classical KdV and Boussinesq equation.
Energy Technology Data Exchange (ETDEWEB)
Henao, Lina J. [Centre de Recherches sur les Macromolecules Vegetales (CERMAV-CNRS), BP53, 38041 Grenoble cedex 9 (France); Mazeau, Karim, E-mail: karim.mazeau@cermav.cnrs.fr [Centre de Recherches sur les Macromolecules Vegetales (CERMAV-CNRS), BP53, 38041 Grenoble cedex 9 (France)
2009-10-15
In soils, the bacterial exopolysaccharides (EPS) aggregate mineral particles, enhancing their cohesion and their ability to retain water. These phenomena have been studied at the atomic scale by molecular modelling; we have considered seven rhizospheric polysaccharides interacting with the basal surfaces of montmorillonite. Models accounted for the aggregation phenomena induced by EPS: some segments of the polysaccharide were adsorbed on the mineral surfaces while others formed loops and bridges linking two surfaces. Adsorption energies were favourable and depended mostly on the interacting area. Cohesion of aggregates was estimated by the adhesion work, predicted values differed from one EPS to the other, suggesting that the chemical structure influences interaction strength with the mineral surface. Mechanisms of water uptake and release have also been investigated: hydration energies revealed that EPS strongly retain water at low water concentrations.
DEFF Research Database (Denmark)
Larsson, Hilde Kristina
Computational fluid dynamics (CFD) is the application of numerical methods to solve systems of partial differential equations related to fluid dynamics. The continuity and the momentum equations are the most commonly applied equations within CFD, and together they can be used to calculate...... the velocity and pressure distributions in a fluid. CFD also enables the modelling of several fluids simultaneously, e.g. gas bubbles in a liquid, as well as the presence of turbulence and dissolved chemicals in a fluid, and many other phenomena. This makes CFD an appreciated tool for studying flow structures...... and an ion-exchange reaction are also modelled and compared to experimental data. The thesis includes a comprehensive overview of the fundamentals behind a CFD software, as well as a more detailed review of the fluid dynamic phenomena investigated in this project. The momentum and continuity equations...
Numerical modelling of thermal and fluid flow phenomena in the mould channel
Directory of Open Access Journals (Sweden)
L. Sowa
2007-12-01
Full Text Available In the paper, a mathematical and a numerical model of the solidification of a cylindrical slender shaped casting, which take into account the process of filling the mould cavity with molten metal, has been proposed. Pressure and velocity fields were obtained by solving the momentum equations and the continuity equation, while the thermal fields were obtained by solving the heat conduction equation containing the convection term. Next, the numerical analysis of the solidification process of metals alloy in a cylindrical mould channel has been made. In the model one takes into account interdependence the heat transfer and fluid flow phenomena. Coupling of the thermal and fluid flow phenomena has been taken into consideration by the changes of the fluidity function and thermophysical parameters of alloy with respect to the temperature. The influence of the pressure and the temperature of metal pouring on the solid phase growth kinetics were estimated. The problem has been solved by the finite element method.
Statistical issues in searches for new phenomena in High Energy Physics
Lyons, Louis; Wardle, Nicholas
2018-03-01
Many analyses of data in High Energy Physics are concerned with searches for New Physics. We review the statistical issues that arise in such searches, and then illustrate these using the specific example of the recent successful search for the Higgs boson, produced in collisions between high energy protons at CERN’s Large Hadron Collider.
Inference of physical phenomena from FFTF [Fast Flux Test Facility] noise analysis
International Nuclear Information System (INIS)
Thie, J.A.; Damiano, B.; Campbell, L.R.
1989-01-01
The source of features observed in noise spectra collected by an automated data collection system operated by the Oak Ridge National Laboratory at the Fast Flux Test Facility (FFTF) can be identified using a methodology based on careful data observation and intuition. When a large collection of data is available, as in this case, automatic pattern recognition and parameter storage and retrieval using a data base can be used to extract useful information. However, results can be limited to empirical signature comparison monitoring unless an effort is made to determine the noise sources. This paper describes the identification of several FFTF noise data phenomena and suggests how this understanding may lead to new or enhanced monitoring. 13 refs., 4 figs
Fluid Physics and Transport Phenomena in a Simulated Reduced Gravity Environment
Lipa, J.
2004-01-01
We describe a ground-based apparatus that allows the cancellation of gravity on a fluid using magnetic forces. The present system was designed for liquid oxygen studies over the range 0.001 - 5 g s. This fluid is an essential component of any flight mission using substantial amounts of liquid propellant, especially manned missions. The apparatus has been used to reduce the hydrostatic compression near the oxygen critical point and to demonstrate inverted phase separation. It could also be used to study pool boiling and two-phase heat transfer in Martian, Lunar or near-zero gravity, as well as phenomena such as Marangoni flow and convective instabilities. These studies would contribute directly to the reliability and optimization of the Moon and Mars flight programs.
Bowers-Morrow, Vivienne M; Ali, Sinan O; Williams, Keith L
2004-08-01
Are there universal molecular mechanisms associated with cell contact phenomena during metazoan ontogenesis? Comparison of adhesion systems in disparate model systems indicates the existence of unifying principles. Requirements for multicellularity are (a) the construction of three-dimensional structures involving a crucial balance between adhesiveness and motility; and (b) the establishment of integration at molecular, cellular, tissue, and organismal levels of organization. Mechanisms for (i) cell-cell and cell-substrate adhesion, (ii) cell movement, (iii) cell-cell communication, (iv) cellular responses, (v) regulation of these processes, and (vi) their integration with patterning, growth, and other developmental processes are all crucial to metazoan development, and must have been present for the emergence and radiation of Metazoa. The principal unifying themes of this review are the dynamics and regulation of cell contact phenomena. Our knowledge of the dynamic molecular mechanisms underlying cell contact phenomena remains fragmentary. Here we examine the molecular bases of cell contact phenomena using extant model developmental systems (representing a wide range of phyla) including the simplest i.e. sponges, and the eukaryotic protist Dictyostelium discoideum, the more complex Drosophila melanogaster, and vertebrate systems. We discuss cell contact phenomena in a broad developmental context. The molecular language of cell contact phenomena is complex; it involves a plethora of structurally and functionally diverse molecules, and diverse modes of intermolecular interactions mediated by protein and/or carbohydrate moieties. Reasons for this are presumably the necessity for a high degree of specificity of intermolecular interactions, the requirement for a multitude of different signals, and the apparent requirement for an increasingly large repertoire of cell contact molecules in more complex developmental systems, such as the developing vertebrate nervous
Cavitation phenomena in mechanical heart valves: studied by using a physical impinging rod system.
Lo, Chi-Wen; Chen, Sheng-Fu; Li, Chi-Pei; Lu, Po-Chien
2010-10-01
When studying mechanical heart valve cavitation, a physical model allows direct flow field and pressure measurements that are difficult to perform with actual valves, as well as separate testing of water hammer and squeeze flow effects. Movable rods of 5 and 10 mm diameter impinged same-sized stationary rods to simulate squeeze flow. A 24 mm piston within a tube simulated water hammer. Adding a 5 mm stationary rod within the tube generated both effects simultaneously. Charged-coupled device (CCD) laser displacement sensors, strobe lighting technique, laser Doppler velocimetry (LDV), particle image velocimetry (PIV) and high fidelity piezoelectric pressure transducers measured impact velocities, cavitation images, squeeze flow velocities, vortices, and pressure changes at impact, respectively. The movable rods created cavitation at critical impact velocities of 1.6 and 1.2 m/s; squeeze flow velocities were 2.8 and 4.64 m/s. The isolated water hammer created cavitation at 1.3 m/s piston speed. The combined piston and stationary rod created cavitation at an impact speed of 0.9 m/s and squeeze flow of 3.2 m/s. These results show squeeze flow alone caused cavitation, notably at lower impact velocity as contact area increased. Water hammer alone also caused cavitation with faster displacement. Both effects together were additive. The pressure change at the vortex center was only 150 mmHg, which cannot generate the magnitude of pressure drop required for cavitation bubble formation. Cavitation occurred at 3-5 m/s squeeze flow, significantly different from the 14 m/s derived by Bernoulli's equation; the temporal acceleration of unsteady flow requires further study.
Superconductivity and superfluidity as universal emergent phenomena in diverse physical systems
International Nuclear Information System (INIS)
Guidry, Mike
2014-01-01
Superconductivity and superfluidity are observed across a strikingly broad range of physical systems. This universality seems unlikely to be coincidental but a unified understanding of superconductivity and superfluidity across these highly disparate fields seems impossible in traditional microscopic terms. I give an overview of superconductivity and superfluidity found in various fermionic condensed matter, nuclear physics, and neutron star systems, and propose that all result from generic algebraic structures for the emergent effective Hamiltonian, with the role of underlying microscopic physics largely relegated to influence on parameter values
Elementary particle physics and high energy phenomena. Progress report for FY92
Energy Technology Data Exchange (ETDEWEB)
Barker, A.R.; Cumalat, J.P.; de Alwis, S.P.; DeGrand, T.A.; Ford, W.T.; Mahanthappa, K.T.; Nauenberg, U.; Rankin, P.; Smith, J.G.
1992-06-01
This report discusses the following research in high energy physics: the properties of the z neutral boson with the SLD detector; the research and development program for the SDC muon detector; the fixed-target k-decay experiments; the Rocky Mountain Consortium for HEP; high energy photoproduction of states containing heavy quarks; and electron-positron physics with the CLEO II and Mark II detectors. (LSP).
Lattice Boltzmann modeling of transport phenomena in fuel cells and flow batteries
Xu, Ao; Shyy, Wei; Zhao, Tianshou
2017-06-01
Fuel cells and flow batteries are promising technologies to address climate change and air pollution problems. An understanding of the complex multiscale and multiphysics transport phenomena occurring in these electrochemical systems requires powerful numerical tools. Over the past decades, the lattice Boltzmann (LB) method has attracted broad interest in the computational fluid dynamics and the numerical heat transfer communities, primarily due to its kinetic nature making it appropriate for modeling complex multiphase transport phenomena. More importantly, the LB method fits well with parallel computing due to its locality feature, which is required for large-scale engineering applications. In this article, we review the LB method for gas-liquid two-phase flows, coupled fluid flow and mass transport in porous media, and particulate flows. Examples of applications are provided in fuel cells and flow batteries. Further developments of the LB method are also outlined.
Phenomena-based Uncertainty Quantification in Predictive Coupled- Physics Reactor Simulations
International Nuclear Information System (INIS)
Adams, Marvin
2017-01-01
This project has sought to develop methodologies, tailored to phenomena that govern nuclearreactor behavior, to produce predictions (including uncertainties) for quantities of interest (QOIs) in the simulation of steady-state and transient reactor behavior. Examples of such predictions include, for each QOI, an expected value as well as a distribution around this value and an assessment of how much of the distribution stems from each major source of uncertainty. The project has sought to test its methodologies by comparing against measured experimental outcomes. The main experimental platform has been a 1-MW TRIGA reactor. This is a flexible platform for a wide range of experiments, including steady state with and without temperature feedback, slow transients with and without feedback, and rapid transients with strong feedback. The original plan was for the primary experimental data to come from in-core neutron detectors. We made considerable progress toward this goal but did not get as far along as we had planned. We have designed, developed, installed, and tested vertical guide tubes, each able to accept a detector or stack of detectors that can be moved axially inside the tube, and we have tested several new detector designs. One of these shows considerable promise.
Phenomena-based Uncertainty Quantification in Predictive Coupled- Physics Reactor Simulations
Energy Technology Data Exchange (ETDEWEB)
Adams, Marvin [Texas A & M Univ., College Station, TX (United States)
2017-06-12
This project has sought to develop methodologies, tailored to phenomena that govern nuclearreactor behavior, to produce predictions (including uncertainties) for quantities of interest (QOIs) in the simulation of steady-state and transient reactor behavior. Examples of such predictions include, for each QOI, an expected value as well as a distribution around this value and an assessment of how much of the distribution stems from each major source of uncertainty. The project has sought to test its methodologies by comparing against measured experimental outcomes. The main experimental platform has been a 1-MW TRIGA reactor. This is a flexible platform for a wide range of experiments, including steady state with and without temperature feedback, slow transients with and without feedback, and rapid transients with strong feedback. The original plan was for the primary experimental data to come from in-core neutron detectors. We made considerable progress toward this goal but did not get as far along as we had planned. We have designed, developed, installed, and tested vertical guide tubes, each able to accept a detector or stack of detectors that can be moved axially inside the tube, and we have tested several new detector designs. One of these shows considerable promise.
Model and numerical analysis of mechanical phenomena of tools steel hardening
Directory of Open Access Journals (Sweden)
A. Bokota
2010-01-01
Full Text Available This paper the model hardening of tool steel takes into considerations of mechanical phenomena is presented. Fields stresses and strains are obtained from solutions by FEM equilibrium equations in rate form. The stresses generated during hardening were assumed to result from thermal load, structural deformation, and plastic deformation and transformation plasticity. Thermophysical values in the constitutive relations are depended upon both the temperature and the phase composition. Condition Huber-Misses with the isotropic strengthening for the creation of plastic strains is used. However model Leblond to determined transformations plasticity applied. The analysis of stresses associated of the elements hardening made of tool steel was done.
Computational Modelling of a Tangentially Fired Boiler With Deposit Formation Phenomena
Directory of Open Access Journals (Sweden)
Modliński Norbert J.
2014-09-01
Full Text Available Any complete CFD model of pulverised coal-fired boiler needs to consider ash deposition phenomena. Wall boundary conditions (temperature and emissivity should be temporally corrected to account for the effects of deposit growth on the combustion conditions. At present voluminous publications concerning ash related problems are available. The current paper presents development of an engineering tool integrating deposit formation models with the CFD code. It was then applied to two tangentially-fired boilers. The developed numerical tool was validated by comparing it with boiler evaporator power variation based on the on-line diagnostic system with the results from the full CFD simulation.
[OsF6]x−: Molecular Models for Spin-Orbit Entangled Phenomena
DEFF Research Database (Denmark)
Pedersen, Kasper Steen; Woodruff, Daniel N.; Singh, Saurabh Kumar
2017-01-01
. Herein, two molecular osmate analogues, [OsF6]2− and [OsF6]−, are reported as model systems for Os4+ and Os5+ centers found in oxides. Using X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) techniques, combined with state-of-the-art ab initio calculations, their ground...... state was elucidated; mirroring the osmium electronic structure in osmates. The realization of such molecular model systems provides a unique chemical playground to engineer materials exhibiting spin-orbit entangled phenomena....
Fluid structure interaction modeling of liquid sloshing phenomena in flexible tanks
International Nuclear Information System (INIS)
Nicolici, S.; Bilegan, R.M.
2013-01-01
Highlights: ► We used Ansys Workbench package to study sloshing phenomena in liquid containers. ► The interaction liquid–structure is modeled considering full and one-way coupling. ► The results obtained with the FSI models were compared against design codes. ► The results have shown that the sloshing is influenced by tank wall elasticity. -- Abstract: The present paper is concerned with the problem of modeling the fluid–structure interaction (FSI) in partially filled liquid containers. The study focuses on the sloshing phenomena and on the coupling computational fluid dynamics (CFD) analysis with the finite element stress analysis (FEA) used to predict the sloshing wave amplitude, convective mode frequency, pressure exerted on the walls and the effect of sloshing on the anchoring points forces. The interaction between fluids (water and air) and tank wall is modeled considering full and one-way coupling. Using the time history of an earthquake excitation, the results of the FSI model are compared with those obtained employing simplified mechanical models given in design codes. The coupling phenomenon was found to influence the sloshing effect, the impulsive pressure being amplified by the wall elasticity. The applied FSI methodology proves to be feasible in analyzing a 3D full coupled CFD/FEA storage tank subjected to a long time history excitation
Directory of Open Access Journals (Sweden)
Jianxun Zhang
2017-10-01
Full Text Available A lithium-Ion battery is a typical degradation product, and its performance will deteriorate over time. In its degradation process, regeneration phenomena have been frequently encountered, which affect both the degradation state and rate. In this paper, we focus on how to build the degradation model and estimate the lifetime. Toward this end, we first propose a multi-phase stochastic degradation model with random jumps based on the Wiener process, where the multi-phase model and random jumps at the changing point are used to describe the variation of degradation rate and state caused by regeneration phenomena accordingly. Owing to the complex structure and random variables, the traditional Maximum Likelihood Estimation (MLE is not suitable for the proposed model. In this case, we treat these random variables as latent parameters, and then develop an approach for model identification based on expectation conditional maximum (ECM algorithm. Moreover, depending on the proposed model, how to estimate the lifetime with fixed changing point is presented via the time-space transformation technique, and the approximate analytical solution is derived. Finally, a numerical simulation and a practical case are provided for illustration.
Encouraging Prospective Teachers to Engage Friends and Family in Exploring Physical Phenomena
Crowl, Michele; Devitt, Adam; Jansen, Henri; van Zee, Emily H.; Winograd, Kenneth J.
2013-01-01
Involving people outside of a science course can foster learning for students enrolled in the course. Assignments involving friends and family provided such opportunities in an undergraduate physics course for prospective teachers. These assignments included reflecting upon prior experiences, interviewing friends and family members, engaging them…
Anomaly! collider physics and the quest for new phenomena at Fermilab
Dorigo, Tommaso
2017-01-01
From the mid-1980s, an international collaboration of 600 physicists embarked on the investigation of subnuclear physics at the high-energy frontier. As well as discovering the top quark, the heaviest elementary particle ever observed, the physicists analyzed their data to seek signals of new physics which could revolutionize our understanding of nature. Anomaly! tells the story of that quest, and focuses specifically on the finding of several unexplained effects which were unearthed in the process. These anomalies proved highly controversial within the large team: to some collaborators they called for immediate publication, while to others their divulgation threatened to jeopardize the reputation of the experiment. Written in a confidential, narrative style, this book looks at the sociology of a large scientific collaboration, providing insight in the relationships between top physicists at the turn of the millennium. The stories offer an insider's view of the life cycle of the "failed" discoveries that un...
International Nuclear Information System (INIS)
Greenberger, D.M.
1978-01-01
We take two rather abstract concepts from elementary particle physics, and show that there actually exist analogs to both of them in undergraduate physics. In the case of spontaneous symmetry breaking, we provide an example where the most symmetrical state of a simple system suddenly becomes unstable, while a less symmetrical state develops lower energy and becomes stable. In the case of scale invariance, we consider an example with no natural scale determined, and show that a straightforward dimensional analysis of the problem leads to incorrect results, because of the occurrence of infinities, even though they would appear to be irrelevant infinities that might not be expected to affect the dimensions of the answer. We then show how a simple use of the scale invariance of the problem leads to the correct answer
Rux, Lorelynn Mary
Deregulation of the electric utility industry has increased the need to monitor the state of powerplant equipment, such as critical generators and motors, to improve availability and reduce life cycle costs via condition-based maintenance. To achieve these goals, nondestructive condition assessment and diagnostic tests are necessary to evaluate the quality and condition of a machine's stator winding insulation system. Periodic tests are generally conducted to monitor insulation aging, diagnose problems, or provide some assurance that the winding has a minimum level of electrical strength. The basic principles of insulation testing are presented herein, and the physical mechanisms that affect the current versus voltage response are described. A stator winding insulation model was developed based on this theoretical foundation for use in understanding and analyzing the macroscopic behavior of complex insulation phenomena. A comprehensive, controlled laboratory experiment was conducted on a set of stator coils that were deliberately manufactured with and without insulation defects. Specific defects were chosen to represent the types of insulation problems typically encountered during manufacture or as a result of in-service aging, and included lack of resin cure, loosely-applied insulating tapes, internal conductive contamination, reduced density of the groundwall insulation, and thermal cycling damage. Results are presented from a series of electrical tests conducted on the coil specimens to compare the effectiveness of various test methods in detecting the different insulation problems. The tests included insulation resistance, polarization index, ramped direct voltage, dissipation factor, dielectric spectroscopy, partial discharge, and recovery voltage measurements. Dielectric principles and testing experience obtained during this investigation were applied to a collection of test results obtained by the author from in-service machines during the past ten years
Hierarchical modeling of plasma and transport phenomena in a dielectric barrier discharge reactor
Bali, N.; Aggelopoulos, C. A.; Skouras, E. D.; Tsakiroglou, C. D.; Burganos, V. N.
2017-12-01
A novel dual-time hierarchical approach is developed to link the plasma process to macroscopic transport phenomena in the interior of a dielectric barrier discharge (DBD) reactor that has been used for soil remediation (Aggelopoulos et al 2016 Chem. Eng. J. 301 353–61). The generation of active species by plasma reactions is simulated at the microseconds (µs) timescale, whereas convection and thermal conduction are simulated at the macroscopic (minutes) timescale. This hierarchical model is implemented in order to investigate the influence of the plasma DBD process on the transport and reaction mechanisms during remediation of polluted soil. In the microscopic model, the variables of interest include the plasma-induced reactive concentrations, while in the macroscopic approach, the temperature distribution, and the velocity field both inside the discharge gap and within the polluted soil material as well. For the latter model, the Navier–Stokes and Darcy Brinkman equations for the transport phenomena in the porous domain are solved numerically using a FEM software. The effective medium theory is employed to provide estimates of the effective time-evolving and three-phase transport properties in the soil sample. Model predictions considering the temporal evolution of the plasma remediation process are presented and compared with corresponding experimental data.
Study of surface phenomena in biomaterials: The influence of physical factors
Sachelarie, Liliana; Vasiliu, Mihaela Papusa; Ciobanu, Catalina
2015-10-01
This study's purpose is pointing out the phenomenon that occurs at time of interaction between the tissue with implant. The materials used are Ti and its alloys. The oral tissue must be compatible with the materials used in surgical implant to human body. The bio-materials surface behavior is influenced by physical characteristics. The methods we use show a number of bio-compatibility aspects. The success of an implant in a hard tissue depends not only on the initial attachment and the osteogenic cells consecutive proliferation, but also on their capacity to create a new bone.
Study of surface phenomena in biomaterials: The influence of physical factors
Energy Technology Data Exchange (ETDEWEB)
Sachelarie, Liliana, E-mail: lisachero@yahoo.com; Vasiliu, Mihaela Papusa; Ciobanu, Catalina
2015-10-15
This study's purpose is pointing out the phenomenon that occurs at time of interaction between the tissue with implant. The materials used are Ti and its alloys. The oral tissue must be compatible with the materials used in surgical implant to human body. The bio-materials surface behavior is influenced by physical characteristics. The methods we use show a number of bio-compatibility aspects. The success of an implant in a hard tissue depends not only on the initial attachment and the osteogenic cells consecutive proliferation, but also on their capacity to create a new bone.
Travelling wave solutions to nonlinear physical models by means of ...
Indian Academy of Sciences (India)
On the other hand, considerable attention has been given to problem of finding spe- cial types of analytic solutions to understand biological, physical and chemical phenomena modelled by NPDEs. Among the possible solutions, certain solutions may depend only on a single combination of variables such as travelling wave ...
High-order Boussinesq-type modelling of nonlinear wave phenomena in deep and shallow water
DEFF Research Database (Denmark)
Madsen, Per A.; Fuhrman, David R.
2010-01-01
In this work, we start with a review of the development of Boussinesq theory for water waves covering the period from 1872 to date. Previous reviews have been given by Dingemans,1 Kirby,2,3 and Madsen & Schäffer.4 Next, we present our most recent high-order Boussinesq-type formulation valid...... for fully nonlinear and highly dispersive waves traveling over a rapidly varying bathymetry. Finally, we cover applications of this Boussinesq model, and we study a number of nonlinear wave phenomena in deep and shallow water. These include (1) Kinematics in highly nonlinear progressive deep-water waves; (2...
Energy Technology Data Exchange (ETDEWEB)
Veshchunov, M.S.; Kisselev, A.E.; Palagin, A.V. [Nuclear Safety Institute, Moscow (Russian Federation)] [and others
1995-09-01
The code package SVECHA for the modeling of in-vessel core degradation (CD) phenomena in severe accidents is being developed in the Nuclear Safety Institute, Russian Academy of Science (NSI RAS). The code package presents a detailed mechanistic description of the phenomenology of severe accidents in a reactor core. The modules of the package were developed and validated on separate effect test data. These modules were then successfully implemented in the ICARE2 code and validated against a wide range of integral tests. Validation results have shown good agreement with separate effect tests data and with the integral tests CORA-W1/W2, CORA-13, PHEBUS-B9+.
Energy Technology Data Exchange (ETDEWEB)
Sahraoui, Melik [Institut Preparatoire aux Etudes d' Ingenieurs de Tunis (IPEIT) (Tunisia); Kharrat, Chafik; Halouani, Kamel [UR: Micro-Electro-Thermal Systems (METS-ENIS), Industrial Energy Systems Group, Institut Preparatoire aux Etudes d' Ingenieurs de Sfax (IPEIS), University of Sfax, B.P: 1172, 3018 Sfax (Tunisia)
2009-04-15
A two-dimensional CFD model of PEM fuel cell is developed by taking into account the electrochemical, mass and heat transfer phenomena occurring in all of its regions simultaneously. The catalyst layers and membrane are each considered as distinct regions with finite thickness and calculated properties such as permeability, local protonic conductivity, and local dissolved water diffusion. This finite thickness model enables to model accurately the protonic current in these regions with higher accuracy than using an infinitesimal interface. In addition, this model takes into account the effect of osmotic drag in the membrane and catalyst layers. General boundary conditions are implemented in a way taking into consideration any given species concentration at the fuel cell inlet, such as water vapor which is a very important parameter in determining the efficiency of fuel cells. Other operating parameters such as temperature, pressure and porosity of the porous structure are also investigated to characterize their effect on the fuel cell efficiency. (author)
The role of fractional calculus in modeling biological phenomena: A review
Ionescu, C.; Lopes, A.; Copot, D.; Machado, J. A. T.; Bates, J. H. T.
2017-10-01
This review provides the latest developments and trends in the application of fractional calculus (FC) in biomedicine and biology. Nature has often showed to follow rather simple rules that lead to the emergence of complex phenomena as a result. Of these, the paper addresses the properties in respiratory lung tissue, whose natural solutions arise from the midst of FC in the form of non-integer differ-integral solutions and non-integer parametric models. Diffusion of substances in human body, e.g. drug diffusion, is also a phenomena well known to be captured with such mathematical models. FC has been employed in neuroscience to characterize the generation of action potentials and spiking patters but also in characterizing bio-systems (e.g. vegetable tissues). Despite the natural complexity, biological systems belong as well to this class of systems, where FC has offered parsimonious yet accurate models. This review paper is a collection of results and literature reports who are essential to any versed engineer with multidisciplinary applications and bio-medical in particular.
Building Mental Models by Dissecting Physical Models
Srivastava, Anveshna
2016-01-01
When students build physical models from prefabricated components to learn about model systems, there is an implicit trade-off between the physical degrees of freedom in building the model and the intensity of instructor supervision needed. Models that are too flexible, permitting multiple possible constructions require greater supervision to…
Modelling of melting and solidification transport phenomena during hypothetical NPP severe accidents
International Nuclear Information System (INIS)
Sarler, B.
1992-01-01
A physical and mathematical framework to deal with the transport phenomena occuring during melting and solidification of the hypothetical NPP severe accidents is presented. It concentrates on the transient temperature, velocity, and species concentration distributions during such events. The framework is based on the Mixture Continuum Formulation of the components and phases, cast in the boundary-domain integral shape structured by the fundamental solution of the Laplace equation. The formulation could cope with various solid-liquid sub-systems through the inclusion of the specific closure relations. The deduced system of boundary-domain integral equations for conservation of mass, energy, momentum, and species could be solved by the boundary element discrete approximative method. (author) [sl
Physical interpretation of geysering phenomena and periodic boiling instability at low flows
International Nuclear Information System (INIS)
Duffey, R.B.; Rohatgi, U.S.
1996-01-01
Over 30 years ago, Griffith showed that unstable and periodic initial boiling occurred in stagnant liquids in heated pipes coupled to a cooler or condensing plenum volume. This was called ''geysering'', and is a similar phenomenon to the rapid nucleation and voiding observed in tubes filled with superheated liquid. It is also called ''bumping'' when non-uniformly heated water or a chemical suddenly boils in laboratory glassware. In engineering, the stability and predictability has importance to the onset of bulk boiling in a natural and forced circulation loops. The latest available data show the observed stability and periodicity of the onset of boiling flow when there is a plenum, multiple heated channels, and a sustained subcooling in a circulating loop. We examine the available data, both old and new, and develop a new theory to illustrate the simple physics causing the observed periodicity of the flow. We examine the validity of the theory by comparison to all the geysering data, and develop a useful and simple correlation. We illustrate the equivalence of the onset of geysering to the onset of static instability in subcooled boiling. We also derive the stability boundary for geysering, utilizing turbulent transport analysis to determine the effects of pressure and other key parameters. This new result explains the greater stability region observed at higher pressures. The paper builds on the 30 years of quite independent thermal hydraulic work that is still fresh and useful today. We discuss the physical interpretation of geysering onset with a consistent theory, and show where refinements would be useful to the data correlations
2015-01-01
This book presents cutting-edge experimental and computational results and provides comprehensive coverage on the impact of non-equilibrium structure and dynamics on the properties of soft matter confined to the nanoscale. The book is organized into three main sections: · Equilibration and physical aging: by treating non-equilibrium phenomena with the formal methodology of statistical physics in bulk, the analysis of the kinetics of equilibration sheds new light on the physical origin of the non-equilibrium character of thin polymer films. Both the impact of sample preparation and that of interfacial interactions are analyzed using a large set of experiments. A historical overview of the investigation of the non-equilibrium character of thin polymer films is also presented. Furthermore, the discussion focuses on how interfaces and geometrical confinement perturb the pathways and kinetics of equilibrations of soft glasses (a process of tremendous technological interest). · Irr...
Haeringen, W. van
In view of remaining obscurities and difficulties in existing treatments of the infrared divergences in quantum electrodynamics this problem has been considered anew. The approximate model introduced in 1937 by Bloch and Nordsieck is rediscussed. It is explicitly shown to be a good substitute for
Lamorski, Krzysztof; Sławiński, Cezary; Barna, Gyöngyi
2014-05-01
There are some important macroscopic properties of the soil porous media such as: saturated permeability and water retention characteristics. These soil characteristics are very important as they determine soil transport processes and are commonly used as a parameters of general models of soil transport processes used extensively for scientific developments and engineering practise. These characteristics are usually measured or estimated using some statistical or phenomenological modelling, i.e. pedotransfer functions. On the physical basis, saturated soil permeability arises from physical transport processes occurring at the pore level. Current progress in modelling techniques, computational methods and X-ray micro-tomographic technology gives opportunity to use direct methods of physical modelling for pore level transport processes. Physically valid description of transport processes at micro-scale based on Navier-Stokes type modelling approach gives chance to recover macroscopic porous medium characteristics from micro-flow modelling. Water microflow transport processes occurring at the pore level are dependent on the microstructure of porous body and interactions between the fluid and the medium. In case of soils, i.e. the medium there exist relatively big pores in which water can move easily but also finer pores are present in which water transport processes are dominated by strong interactions between the medium and the fluid - full physical description of these phenomena is a challenge. Ten samples of different soils were scanned using X-ray computational microtomograph. The diameter of samples was 5 mm. The voxel resolution of CT scan was 2.5 µm. Resulting 3D soil samples images were used for reconstruction of the pore space for further modelling. 3D image threshholding was made to determine the soil grain surface. This surface was triangulated and used for computational mesh construction for the pore space. Numerical modelling of water flow through the
Exploring large-scale phenomena in composite membranes through an efficient implicit-solvent model
International Nuclear Information System (INIS)
Laradji, Mohamed; Sunil Kumar, P B; Spangler, Eric J
2016-01-01
Several microscopic and mesoscale models have been introduced in the past to investigate various phenomena in lipid membranes. Most of these models account for the solvent explicitly. Since in a typical molecular dynamics simulation, the majority of particles belong to the solvent, much of the computational effort in these simulations is devoted for calculating forces between solvent particles. To overcome this problem, several implicit-solvent mesoscale models for lipid membranes have been proposed during the last few years. In the present article, we review an efficient coarse-grained implicit-solvent model we introduced earlier for studies of lipid membranes. In this model, lipid molecules are coarse-grained into short semi-flexible chains of beads with soft interactions. Through molecular dynamics simulations, the model is used to investigate the thermal, structural and elastic properties of lipid membranes. We will also review here few studies, based on this model, of the phase behavior of nanoscale liposomes, cytoskeleton-induced blebbing in lipid membranes, as well as nanoparticles wrapping and endocytosis by tensionless lipid membranes. (topical review)
Taw, Matthew R.
The hardness and reduced modulus of aspirin, RDX, HMX, TATB, FOX-7, ADAAF, and TNT/CL-20 were experimentally measured with nanoindentation. These values are reported for the first time using as-received micron sized crystals of energetic materials with no additional mechanical processing. The results for TATB, ADAAF, and TNT/CL-20 are the first of their kind, while comparisons to previous nanoindentation studies on large, carefully grown single crystals of the other energetic materials show that mechanical properties of the larger crystals are comparable to crystals in the condition they are practically used. Measurements on aspirin demonstrate the variation that can occur between nanoindentation indents based on the orientation of a Berkovich tip relative to the surface of the sample. The Hertzian elastic contact model was used to analyze the materials initial yield, or pop-in, behavior. The length, energy, indentation load, and shear stress at initial yielding were used to characterize each material. For the energetic materials the length and energy of the yield excursions were compared to the drop weight sensitivity. This comparison revealed a general trend that more impact sensitive materials have longer, more severe pop-in excursions. Hot spot initiation mechanisms involving crystal defects such as void collapses and dislocation pile-up followed by avalanche are supported by these trends. While this only takes one aspect of impact sensitivity into consideration, if this trend is observed in a larger range of energetics these methods could possibly be used to great advantage in the early stages of new explosives synthesis to obtain an estimation of drop weight sensitivity.
High-order Boussinesq-type modelling of nonlinear wave phenomena in deep and shallow water
DEFF Research Database (Denmark)
Madsen, Per A.; Fuhrman, David R.
2010-01-01
In this work, we start with a review of the development of Boussinesq theory for water waves covering the period from 1872 to date. Previous reviews have been given by Dingemans,1 Kirby,2,3 and Madsen & Schäffer.4 Next, we present our most recent high-order Boussinesq-type formulation valid...... for fully nonlinear and highly dispersive waves traveling over a rapidly varying bathymetry. Finally, we cover applications of this Boussinesq model, and we study a number of nonlinear wave phenomena in deep and shallow water. These include (1) Kinematics in highly nonlinear progressive deep-water waves; (2......) Kinematics in progressive solitary waves; (3) Reflection of solitary waves from a vertical wall; (4) Reflection and diffraction around a vertical plate; (5) Quartet and quintet interactions and class I and II instabilities; (6) Extreme events from focused directionally spread waveelds; (7) Bragg scattering...
International Nuclear Information System (INIS)
Pulkkanen, V.-M.; Nordman, H.
2010-03-01
Traditional radionuclide transport models overestimate significantly some phenomena, or completely ignore them. This motivates the development of new more precise models. As a result, this work is a description of commissioning of a new KBS-3V near-field radionuclide transport model, which has been done with a commercial software called GoldSim. According to earlier models, GoldSim model uses rz coordinates, but the solubilities of radionuclides have been treated more precisely. To begin with, the physical phenomena concerning near-field transport have been introduced according to GoldSim way of thinking. Also, the computational methods of GoldSim have been introduced and compared to methods used earlier. The actual verification of GoldSim model has been carried out by comparing the GoldSim results from simple cases to the corresponding results obtained with REPCOM, a software developed by VTT and used in several safety assessments. The results agree well. Finally, a few complicated cases were studied. In these cases, the REPCOM's limitations in handling of some phenomena become evident. The differences in the results are caused especially by the extension of the solubility limit to the whole computational domain, and the element-wise treatment of the solubilities which was used instead of nuclide-wise treatment. This work has been carried out as a special assignment to the former laboratory of Advanced Energy Systems in Helsinki University of Technology. The work was done at VTT. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Pulkkanen, V.-M.; Nordman, H. (VTT Technical Research Centre, Espoo (Finland))
2010-03-15
Traditional radionuclide transport models overestimate significantly some phenomena, or completely ignore them. This motivates the development of new more precise models. As a result, this work is a description of commissioning of a new KBS-3V near-field radionuclide transport model, which has been done with a commercial software called GoldSim. According to earlier models, GoldSim model uses rz coordinates, but the solubilities of radionuclides have been treated more precisely. To begin with, the physical phenomena concerning near-field transport have been introduced according to GoldSim way of thinking. Also, the computational methods of GoldSim have been introduced and compared to methods used earlier. The actual verification of GoldSim model has been carried out by comparing the GoldSim results from simple cases to the corresponding results obtained with REPCOM, a software developed by VTT and used in several safety assessments. The results agree well. Finally, a few complicated cases were studied. In these cases, the REPCOM's limitations in handling of some phenomena become evident. The differences in the results are caused especially by the extension of the solubility limit to the whole computational domain, and the element-wise treatment of the solubilities which was used instead of nuclide-wise treatment. This work has been carried out as a special assignment to the former laboratory of Advanced Energy Systems in Helsinki University of Technology. The work was done at VTT. (orig.)
Chiou, Guo-Li
2013-01-01
Although prediction is claimed to be a prime function of mental models, to what extent students can run their mental models to make predictions of physical phenomena remains uncertain. The purpose of this study, therefore, was first to investigate 30 physics students' mental models of heat convection, and then to examine the relationship between…
Finite element modeling of heating phenomena of cracks excited by high-intensity ultrasonic pulses
International Nuclear Information System (INIS)
Chen Zhao-Jiang; Zheng Jiang; Zhang Shu-Yi; Mi Xiao-Bing; Zheng Kai
2010-01-01
A three-dimensional thermo-mechanical coupled finite element model is built up to simulate the phenomena of dynamical contact and frictional heating of crack faces when the plate containing the crack is excited by high-intensity ultrasonic pulses. In the finite element model, the high-power ultrasonic transducer is modeled by using a piezoelectric thermal-analogy method, and the dynamical interaction between both crack faces is modeled using a contact-impact theory. In the simulations, the frictional heating taking place at the crack faces is quantitatively calculated by using finite element thermal-structural coupling analysis, especially, the influences of acoustic chaos to plate vibration and crack heating are calculated and analysed in detail. Meanwhile, the related ultrasonic infrared images are also obtained experimentally, and the theoretical simulation results are in agreement with that of the experiments. The results show that, by using the theoretical method, a good simulation of dynamic interaction and friction heating process of the crack faces under non-chaotic or chaotic sound excitation can be obtained
Transient vibration phenomena in deep mine hoisting cables. Part 1: Mathematical model
Kaczmarczyk, S.; Ostachowicz, W.
2003-04-01
The classical moving co-ordinate frame approach and Hamilton's principle are employed to derive a distributed-parameter mathematical model to investigate the dynamic behaviour of deep mine hoisting cables. This model describes the coupled lateral-longitudinal dynamic response of the cables in terms of non-linear partial differential equations that accommodate the non-stationary nature of the system. Subsequently, the Rayleigh-Ritz procedure is applied to formulate a discrete mathematical model. Consequently, a system of non-linear non-stationary coupled second order ordinary differential equations arises to govern the temporal behaviour of the cable system. This discrete model with quadratic and cubic non-linear terms describes the modal interactions between lateral oscillations of the catenary cable and longitudinal oscillations of the vertical rope. It is shown that the response of the catenary-vertical rope system may feature a number of resonance phenomena, including external, parametric and autoparametric resonances. The parameters of a typical deep mine winder are used to identify the depth locations of the resonance regions during the ascending cycles with various winding velocities.
Capozza, R.; Vanossi, A.; Benassi, A.; Tosatti, E.
2015-02-01
Electrical charging of parallel plates confining a model ionic liquid down to nanoscale distances yields a variety of charge-induced changes in the structural features of the confined film. That includes even-odd switching of the structural layering and charging-induced solidification and melting, with important changes of local ordering between and within layers, and of squeezout behavior. By means of molecular dynamics simulations, we explore this variety of phenomena in the simplest charged Lennard-Jones coarse-grained model including or excluding the effect a neutral tail giving an anisotropic shape to one of the model ions. Using these models and open conditions permitting the flow of ions in and out of the interplate gap, we simulate the liquid squeezout to obtain the distance dependent structure and forces between the plates during their adiabatic approach under load. Simulations at fixed applied force illustrate an effective electrical pumping of the ionic liquid, from a thick nearly solid film that withstands the interplate pressure for high plate charge to complete squeezout following melting near zero charge. Effective enthalpy curves obtained by integration of interplate forces versus distance show the local minima that correspond to layering and predict the switching between one minimum and another under squeezing and charging.
International Nuclear Information System (INIS)
Garion, C.; Skoczen, B.
2004-01-01
A majority of the thin-walled components subjected to intensive plastic straining at cryogenic temperatures are made of stainless steels. The examples of such components can be found in the interconnections of particle accelerators, containing the superconducting magnets, where the thermal contraction is absorbed by thin-walled, axisymmetric shells called bellows expansion joints. The stainless steels show three main phenomena induced by plastic strains at cryogenic temperatures: serrated (discontinuous) yielding, γ→α' phase transformation and anisotropic ductile damage. In the present paper, a coupled constitutive model of γ→α' phase transformation and orthotropic ductile damage is presented. A kinetic law of phase transformation, and a kinetic law of evolution of orthotropic damage are presented. The model is extended to anisotropic plasticity comprising a constant anisotropy (texture effect), which can be classically taken into account by the Hill yield surface, and plastic strain induced anisotropy. For such a model the shape of the yield surface in the stress space varies as a function of the plastic strains. The constitutive model creates a bridge between material science (experiments) and structural analysis. It has been used to predict the response of beam vacuum and cryogenic bellows to monotonic and cyclic loads developed in the interconnections of the Large Hadron Collider at CERN
Wu, M; Li, J; Ludwig, A; Kharicha, A
2014-09-01
Part 1 of this two-part investigation presented a multiphase solidification model incorporating the finite diffusion kinetics and ternary phase diagram with the macroscopic transport phenomena (Wu et al., 2013). In Part 2, the importance of proper treatment of the finite diffusion kinetics in the calculation of macrosegregation is addressed. Calculations for a two-dimensional (2D) square casting (50 × 50 mm 2 ) of Fe-0.45 wt.%C-1.06 wt.%Mn considering thermo-solutal convection and crystal sedimentation are performed. The modeling result indicates that the infinite liquid mixing kinetics as assumed by classical models (e.g., the Gulliver-Scheil or lever rule), which cannot properly consider the solute enrichment of the interdendritic or inter-granular melt at the early stage of solidification, might lead to an erroneous estimation of the macrosegregation. To confirm this statement, further theoretical and experimental evaluations are desired. The pattern and intensity of the flow and crystal sedimentation are dependent on the crystal morphologies (columnar or equiaxed); hence, the potential error of the calculated macrosegregation caused by the assumed growth kinetics depends on the crystal morphology. Finally, an illustrative simulation of an engineering 2.45-ton steel ingot is performed, and the results are compared with experimental results. This example demonstrates the model applicability for engineering castings regarding both the calculation efficiency and functionality.
Physical Modeling Modular Boxes: PHOXES
DEFF Research Database (Denmark)
Gelineck, Steven; Serafin, Stefania
2010-01-01
This paper presents the development of a set of musical instruments, which are based on known physical modeling sound synthesis techniques. The instruments are modular, meaning that they can be combined in various ways. This makes it possible to experiment with physical interaction and sonic...
One-Dimensional, Two-Phase Flow Modeling Toward Interpreting Motor Slag Expulsion Phenomena
Kibbey, Timothy P.
2012-01-01
Aluminum oxide slag accumulation and expulsion was previously shown to be a player in various solid rocket motor phenomena, including the Space Shuttle's Reusable Solid Rocket Motor (RSRM) pressure perturbation, or "blip," and phantom moment. In the latter case, such un ]commanded side accelerations near the end of burn have also been identified in several other motor systems. However, efforts to estimate the mass expelled during a given event have come up short. Either bulk calculations are performed without enough physics present, or multiphase, multidimensional Computational Fluid Dynamic analyses are performed that give a snapshot in time and space but do not always aid in grasping the general principle. One ]dimensional, two ]phase compressible flow calculations yield an analytical result for nozzle flow under certain assumptions. This can be carried further to relate the bulk motor parameters of pressure, thrust, and mass flow rate under the different exhaust conditions driven by the addition of condensed phase mass flow. An unknown parameter is correlated to airflow testing with water injection where mass flow rates and pressure are known. Comparison is also made to full ]scale static test motor data where thrust and pressure changes are known and similar behavior is shown. The end goal is to be able to include the accumulation and flow of slag in internal ballistics predictions. This will allow better prediction of the tailoff when much slag is ejected and of mass retained versus time, believed to be a contributor to the widely-observed "flight knockdown" parameter.
Dissipative phenomena in condensed matter some applications
Dattagupta, Sushanta
2004-01-01
From the field of nonequilibrium statistical physics, this graduate- and research-level volume treats the modeling and characterization of dissipative phenomena. A variety of examples from diverse disciplines like condensed matter physics, materials science, metallurgy, chemical physics etc. are discussed. Dattagupta employs the broad framework of stochastic processes and master equation techniques to obtain models for a wide range of experimentally relevant phenomena such as classical and quantum Brownian motion, spin dynamics, kinetics of phase ordering, relaxation in glasses, dissipative tunneling. It provides a pedagogical exposition of current research material and will be useful to experimentalists, computational physicists and theorists.
Physics Beyond the Standard Model
Ellis, John
2009-01-01
The Standard Model is in good shape, apart possibly from g_\\mu - 2 and some niggling doubts about the electroweak data. Something like a Higgs boson is required to provide particle masses, but theorists are actively considering alternatives. The problems of flavour, unification and quantum gravity will require physics beyond the Standard Model, and astrophysics and cosmology also provide reasons to expect physics beyond the Standard Model, in particular to provide the dark matter and explain the origin of the matter in the Universe. Personally, I find supersymmetry to be the most attractive option for new physics at the TeV scale. The LHC should establish the origin of particle masses has good prospects for discovering dark matter, and might also cast light on unification and even quantum gravity. Important roles may also be played by lower-energy experiments, astrophysics and cosmology in the searches for new physics beyond the Standard Model.
International Nuclear Information System (INIS)
Ahmadi, A.; Meyer, M.; Rouzineau, D.; Prevost, M.; Alix, P.; Laloue, N.
2010-01-01
This paper gives the first step of the development of a rigorous multicomponent reactive separation model. Such a model is highly essential to further the optimization of acid gases removal plants (CO 2 capture, gas treating, etc.) in terms of size and energy consumption, since chemical solvents are conventionally used. Firstly, two main modelling approaches are presented: the equilibrium-based and the rate-based approaches. Secondly, an extended rate-based model with rigorous modelling methodology for diffusion-reaction phenomena is proposed. The film theory and the generalized Maxwell-Stefan equations are used in order to characterize multicomponent interactions. The complete chain of chemical reactions is taken into account. The reactions can be kinetically controlled or at chemical equilibrium, and they are considered for both liquid film and liquid bulk. Thirdly, the method of numerical resolution is described. Coupling the generalized Maxwell-Stefan equations with chemical equilibrium equations leads to a highly non-linear Differential-Algebraic Equations system known as DAE index 3. The set of equations is discretized with finite-differences as its integration by Gear method is complex. The resulting algebraic system is resolved by the Newton- Raphson method. Finally, the present model and the associated methods of numerical resolution are validated for the example of esterification of methanol. This archetype non-electrolytic system permits an interesting analysis of reaction impact on mass transfer, especially near the phase interface. The numerical resolution of the model by Newton-Raphson method gives good results in terms of calculation time and convergence. The simulations show that the impact of reactions at chemical equilibrium and that of kinetically controlled reactions with high kinetics on mass transfer is relatively similar. Moreover, the Fick's law is less adapted for multicomponent mixtures where some abnormalities such as counter
Surface physics theoretical models and experimental methods
Mamonova, Marina V; Prudnikova, I A
2016-01-01
The demands of production, such as thin films in microelectronics, rely on consideration of factors influencing the interaction of dissimilar materials that make contact with their surfaces. Bond formation between surface layers of dissimilar condensed solids-termed adhesion-depends on the nature of the contacting bodies. Thus, it is necessary to determine the characteristics of adhesion interaction of different materials from both applied and fundamental perspectives of surface phenomena. Given the difficulty in obtaining reliable experimental values of the adhesion strength of coatings, the theoretical approach to determining adhesion characteristics becomes more important. Surface Physics: Theoretical Models and Experimental Methods presents straightforward and efficient approaches and methods developed by the authors that enable the calculation of surface and adhesion characteristics for a wide range of materials: metals, alloys, semiconductors, and complex compounds. The authors compare results from the ...
CFD-modeling of insulation debris transport phenomena in water flow
Energy Technology Data Exchange (ETDEWEB)
Krepper, Eckhard, E-mail: E.Krepper@fzd.d [Forschungszentrum Dresden-Rossendorf, Institute of Safety Research, Bautzner Landstrasse 128, 01328 Dresden (Germany); Cartland-Glover, Gregory; Grahn, Alexander; Weiss, Frank-Peter [Forschungszentrum Dresden-Rossendorf, Institute of Safety Research, Bautzner Landstrasse 128, 01328 Dresden (Germany); Alt, Soeren; Hampel, Rainer; Kaestner, Wolfgang; Seeliger, Andre [University of Applied Sciences Zittau/Goerlitz (FH), Theodor-Koerner-Allee 16, 02763 Zittau (Germany)
2010-09-15
The investigation of insulation debris generation, transport and sedimentation becomes important with regard to reactor safety research for PWR and BWR, when considering the long-term behavior of emergency core cooling systems during all types of loss of coolant accidents (LOCA). The insulation debris released near the break during a LOCA incident consists of a mixture of disparate particle population that varies with size, shape, consistency and other properties. Some fractions of the released insulation debris can be transported into the reactor sump, where it may perturb/impinge on the emergency core cooling systems. Open questions of generic interest are the sedimentation of the insulation debris in a water pool, its possible re-suspension and transport in the sump water flow and the particle load on strainers and corresponding pressure drop. A joint research project on such questions is being performed in cooperation between the University of Applied Sciences Zittau/Goerlitz and the Forschungszentrum Dresden-Rossendorf. The project deals with the experimental investigation of particle transport phenomena in coolant flow and the development of CFD models for its description. While the experiments are performed at the University at Zittau/Goerlitz, the theoretical modeling efforts are concentrated at Forschungszentrum Dresden-Rossendorf. In the current paper the basic concepts for CFD-modeling are described and feasibility studies including the conceptual design of the experiments are presented.
Altarelli, Guido
1999-01-01
Introduction structure of gauge theories. The QEDand QCD examples. Chiral theories. The electroweak theory. Spontaneous symmetry breaking. The Higgs mechanism Gauge boson and fermion masses. Yukawa coupling. Charges current couplings. The Cabibo-Kobayashi-Maskawa matrix and CP violation. Neutral current couplings. The Glasow-Iliopoulos-Maiani mechanism. Gauge boson and Higgs coupling. Radiative corrections and loops. Cancellation of the chiral anomaly. Limits on the Higgs comparaison. Problems of the Standard Model. Outlook.
Modeling Solar Atmospheric Phenomena with AtomDB and PyAtomDB
Dupont, Marcus; Foster, Adam
2018-01-01
Taking advantage of the modeling tools made available by PyAtomDB (Foster 2015), we evaluated the impact of changing atomic data on solar phenomena, in particular their effects on models of coronal mass ejections (CME). Intitially, we perform modifications to the canonical SunNEI code (Murphy et al. 2011) in order to include non-equilibrium ionization (NEI) processes that occur in the CME modeled in SunNEI. The methods used involve the consideration of radiaitive cooling as well as ion balance calculations. These calculations were subsequently implemented within the SunNEI simulation. The insertion of aforementioned processes and parameter customizaton produced quite similar results of the original except for the case of iron. These differences were traced to inconsistencies in the recombination rates for Argon-like iron ions between the CHIANTI and AtomDB databases, even though they in theory use the same data. The key finding was that theoretical models are greatly impacted by the relative atomic database update cycles.Following the SunNEI comparison, we then use the AtomDB database to model the time depedencies of intensity flux spikes produced by a coronal shock wave (Ma et al. 2011). We produced a theretical representation for an ionizing plasma that interpolated over the intensity in four Astronomical Imaging Assembly (AIA) filters. Specifically, the 171 A (Fe IX) ,193 A (Fe XII, FeXXIV),211 A (Fe XIV),and 335 A (Fe XVI) wavelengths in order to assess the comparative spectral emissions between AtomDB and the observed data. The results of the theoretical model, in principle, shine light on both the equilibrium conditions before the shock and the non-equilibrium response to the shock front, as well as discrepancies introduced by changing the atomic data.
Nonlinear surface electromagnetic phenomena
Ponath, H-E
1991-01-01
In recent years the physics of electromagnetic surface phenomena has developed rapidly, evolving into technologies for communications and industry, such as fiber and integrated optics. The variety of phenomena based on electromagnetism at surfaces is rich and this book was written with the aim of summarizing the available knowledge in selected areas of the field. The book contains reviews written by solid state and optical physicists on the nonlinear interaction of electromagnetic waves at and with surfaces and films. Both the physical phenomena and some potential applications are
Science and Paranormal Phenomena
Energy Technology Data Exchange (ETDEWEB)
Noyes, H. Pierre
1999-06-03
In order to ground my approach to the study of paranormal phenomena, I first explain my operational approach to physics, and to the ''historical'' sciences of cosmic, biological, human, social and political evolution. I then indicate why I believe that ''paranormal phenomena'' might-but need not- fit into this framework. I endorse the need for a new theoretical framework for the investigation of this field presented by Etter and Shoup at this meeting. I close with a short discussion of Ted Bastin's contention that paranormal phenomena should be defined as contradicting physics.
MODELLING OF SCENARIOS OF THE CRISIS PHENOMENA TRANSFER AMONG FINANCIAL MARKETS
Directory of Open Access Journals (Sweden)
Inna Strelchenko
2017-11-01
Full Text Available The phenomenon of crisis transference among financial markets in different countries is especially evident during the global financial crisis of 2007-2009. Abnormal imbalances emerged in the market of secondary financial instruments in the United States in the second half of 2006 and quickly spread to the financial markets of most countries of the world. However, the rate of fall of the main macroeconomic indicators, the duration of the latent period (the time between the date of the beginning of the financial crisis in the source country and date of the recorded fall in GDP of the country that is subjected to “contagion” (Strelchenko, 2016, and recovery period are substantially different. To generate an effective economic policy actually, there is a task of determining the possible scenarios of transferring crisis. The research subject is a process of transfer of the crisis phenomena among the financial markets of countries with different levels of economic development. Methodology. The paper presents the results of a study on the differentiation of the financial markets reactions to the crisis transfer. To build the corresponding classification model, self-organization Kohonen neural networks are used. The purpose of this work is to build a neural network model for clustering economies according to the response to external financial shocks. This model allows predicting the scenarios of transferring crisis among financial markets. Conclusion. As a result of the study, there is built a neural network with the architecture of the Kohonen map. The neural network has one hidden layer consisting of six neurons and has a hexagonal structure. Six clusters describe six possible scenarios of the economy dynamics under the impact of the transfer of crises. Cluster number one and two unite countries characterized by a short period of economic recovery and return of the main macroeconomic indicators to the precrisis levels. A longer recovery period and
DEFF Research Database (Denmark)
Nielsen, Mads Pagh; Andreasen, Søren Juhl; Rasmussen, Peder Lund
2009-01-01
Degradation phenomena in HTPEM fuel cells for use in CHP systems were investigated experimentally and by modeling. It was found that the two main degradation mechanisms in HTPEM fuel cells are carbon corrosion and Pt agglomeration. On basis of this conclusion a mechanistic model, describing the d...
International Nuclear Information System (INIS)
Peccei, R.D.
1986-01-01
Possible small extensions of the standard model are considered, which are motivated by the strong CP problem and by the baryon asymmetry of the Universe. Phenomenological arguments are given which suggest that imposing a PQ symmetry to solve the strong CP problem is only tenable if the scale of the PQ breakdown is much above M W . Furthermore, an attempt is made to connect the scale of the PQ breakdown to that of the breakdown of lepton number. It is argued that in these theories the same intermediate scale may be responsible for the baryon number of the Universe, provided the Kuzmin Rubakov Shaposhnikov (B+L) erasing mechanism is operative. (orig.)
Point reflector model for the simulation of radar target glint and Doppler phenomena
Grubeck, H.
1995-02-01
This report describes the mathematics of a radar model for the simulation of glint and Doppler phenomena. Glint is an unwanted phenomenon, which deteriorates radar tracking performance. The term denotes a fluctuation of the target direction, experienced by a radar, tracking a complex target. Doppler shift refers to the frequency change of a radar wave, due to the reflection against a moving target. It can be used by modern so-called coherent radar systems for velocity determination. A three-dimensional space is modeled, containing a rigid body of point scattering reflectors (the target) and a point of measuring (the radar). The target and the radar can move freely and independently in the space. The movement of the target and the radar is described with a number of coordinate systems, which are presented in this report. Some simple simulations are also presented in this report. A simulation tool is available for interested users and the purpose of this report is to announce its existence. The program is written in MATLAB Simulink.
Serebrennikov, Aleksey M.
2014-09-01
Here, we introduce a nonlinear continuum mechanical theoretical model of dissipative plasmonic oscillations relying on the principle of least action. The proposed theory has allowed obtaining the expression of a stress tensor for an “electron gas-ionic frame” system. In parallel, an initial boundary value problem for nonlinear integrodifferential equations constituting the model has been formulated. On the basis of a finite-difference approach the iterative solution method, algorithm and solver have been worked out. Thereby we have investigated the phenomena of harmonic multiples generation by a cluster of metal nanoparticles. Also by using these tools the estimate of the density function parameter satisfying the requirement of regular oscillations has been obtained numerically. On the ground of extensive numerical runs it was found that for a given set of parameters the system response turned out to be mainly linear, however the contributions of the closest odd harmonic multiples (third and fifth) were well resolved under quantitative analysis. This result allows the nonlinearity governable by the principal equation of motion to be associated with Kerr's type nonlinearity.
DEFF Research Database (Denmark)
Hu, Haitao; Tao, Haidong; Blaabjerg, Frede
2018-01-01
This paper presents an impedance-based model to systematically investigate the interaction performance of multiple trains and traction network interaction system, aiming to evaluate the serious phenomena, including low-frequency oscillation (LFO), harmonic resonance and resonance instability....... The train-network interaction mechanism is therefore studied and one presents a detailed coupling model for investigating the three interactive phenomena and their characteristics, influential factors, analysis methods and possible mitigation schemes. In the Part I of the two-part paper, the measured...
Directory of Open Access Journals (Sweden)
Fornalczyk A.
2016-06-01
Full Text Available The recovery of precious metals is necessary for environmental and economic reasons. Spent catalysts from automotive industry containing precious metals are very attractive recyclable material as the devices have to be periodically renovated and eventually replaced. This paper presents the method of removing platinum from the spent catalytic converters applying lead as a collector metal in a device used to wash out by using mangetohydrodynamic stirrer. The article includes the description of the methods used for modeling of magnetohydrodynamic phenomena (coupled analysis of the electromagnetic, temperature and flow fields occurring in this particular device. The paper describes the general phenomena and ways of coupling the various physical fields for this type of calculation. The basic computational techniques with a discussion of their advantages and disadvantages are presented.
Modeling interfacial slag layer phenomena in the shell/mold gap in continuous casting of steel
Meng, Ya
A new lubrication and friction model of slag in the interfacial gap was combined into an existing 1-D heat transfer model, CON1D. Analytical transient models of liquid slag flow and solid slag stress have been coupled with a finite-difference model of heat transfer in the mold, gap and steel shell to predict transient shear stress, friction, slip and fracture of the slag layers. Experimental work was conducted to measure the properties of slag powder, including the friction coefficient at elevated temperatures and viscosity near solidification temperature. Tests with wide cooling rates range were conducted to construct CCT curves and to predict critical cooling rates of two slags with different crystallization tendencies. Slag composition and microstructure were analyzed by XRD and SEM. The CON1D model predicts shell thickness, temperature distributions in the mold and shell, slag layers thickness, heat flux profiles down the mold, cooling water temperature rise, ideal taper of the mold walls, and other related phenomena. Plants measurements from operating casters were collected to calibrate the model. The model was then applied to study the effect of casting speed and powder viscosity properties on slag layer behavior. The study finds that liquid slag lubrication would produce negligible stresses. Lower mold slag consumption rate leads to higher solid friction and results in solid slag layer fracture and movement if it falls below a critical value. Mold friction and fracture are governed by lubrication consumption rate. The high measured friction force in operating casters could be due to three sources: an intermittent moving solid slag layer, excessive mold taper or mold misalignment. The model was also applied to interpret the crystallization behavior of slag. A mechanism for the formation of this crystalline layer was proposed that combined the effects of a shift in the viscosity curve, a decrease in the liquid slag conductivity due to partial crystallization
Energy Technology Data Exchange (ETDEWEB)
Rauck, St
2000-10-01
The aim of this work is to develop a scheme for experimental reactors, based on transport equations. This type of reactors is characterized by a small core, a complex, very heterogeneous geometry and a large leakage. The possible insertion of neutron beams in the reflector and the presence of absorbers in the core increase the difficulty of the 3D-geometrical description and the physical modeling of the component parameters of the reactor. The Orphee reactor has been chosen for our study. Physical models (homogenization, collapsing cross section in few groups, albedo multigroup condition) have been developed in the APOLLO2 and CRONOS2 codes to calculate flux and power maps in a 3D-geometry, with different burnup and through transport equations. Comparisons with experimental measurements have shown the interest of taking into account anisotropy, steep flux gradients by using Sn methods, and on the other hand using a 12-group cross section library. The modeling of neutron beams has been done outside the core modeling through Monte Carlo calculations and with the total geometry, including a large thickness of heavy water. Thanks to this calculations, one can evaluate the neutron beams anti-reactivity and determinate the core cycle. We assure these methods more accurate than usual transport-diffusion calculations will be used for the conception of new research reactors. (author)
International Nuclear Information System (INIS)
Li, H.; Kudinov, P.; Villanueva, W.
2011-06-01
This work pertains to the research program on Containment Thermal-Hydraulics at KTH. The objective is to evaluate and improve performance of methods, which are used to analyze thermal-hydraulics of steam suppression pools in a BWR plant under different abnormal transient and accident conditions. The pressure suppression pool was designed to have the capability as a heat sink to cool and condense steam released from the core vessel and/or main steam line during loss of coolant accident (LOCA) or opening of safety relief valve in normal operation of BWRs. For the case of small flow rates of steam influx, thermal stratification could develop on the part above the blowdown pipe exit and significantly impede the pool's pressure suppression capacity. Once steam flow rate increases significantly, momentum introduced by the steam injection and/or periodic expansion and collapse of large steam bubbles due to direct contact condensation can destroy stratified layers and lead to mixing of the pool water. We use CFD-like model of the general purpose thermal-hydraulic code GOTHIC for addressing the issues of stratification and mixing in the pool. In the previous works we have demonstrated that accurate and computationally efficient prediction of the pool thermal-hydraulics in the scenarios with transition between thermal stratification and mixing, presents a computational challenge. The reason is that direct contact condensation phenomena, which drive oscillatory motion of the water in the blowdown pipes, are difficult to simulate with original GOTHIC models because of appearance of artificial oscillations due to numerical disturbances. To resolve this problem we propose to model the effect of steam injection on the mixing and stratification with the Effective Heat Source (EHS) model and the Effective Momentum Source (EMS) model. We use POOLEX/PPOOLEX experiment (Lappeenranta University of Technology in Finland), in order to (a) quantify errors due to GOTHIC's physical models
Energy Technology Data Exchange (ETDEWEB)
Li, H.; Kudinov, P.; Villanueva, W. (Royal Institute of Technology (KTH). Div. of Nuclear Power Safety (Sweden))
2011-06-15
This work pertains to the research program on Containment Thermal-Hydraulics at KTH. The objective is to evaluate and improve performance of methods, which are used to analyze thermal-hydraulics of steam suppression pools in a BWR plant under different abnormal transient and accident conditions. The pressure suppression pool was designed to have the capability as a heat sink to cool and condense steam released from the core vessel and/or main steam line during loss of coolant accident (LOCA) or opening of safety relief valve in normal operation of BWRs. For the case of small flow rates of steam influx, thermal stratification could develop on the part above the blowdown pipe exit and significantly impede the pool's pressure suppression capacity. Once steam flow rate increases significantly, momentum introduced by the steam injection and/or periodic expansion and collapse of large steam bubbles due to direct contact condensation can destroy stratified layers and lead to mixing of the pool water. We use CFD-like model of the general purpose thermal-hydraulic code GOTHIC for addressing the issues of stratification and mixing in the pool. In the previous works we have demonstrated that accurate and computationally efficient prediction of the pool thermal-hydraulics in the scenarios with transition between thermal stratification and mixing, presents a computational challenge. The reason is that direct contact condensation phenomena, which drive oscillatory motion of the water in the blowdown pipes, are difficult to simulate with original GOTHIC models because of appearance of artificial oscillations due to numerical disturbances. To resolve this problem we propose to model the effect of steam injection on the mixing and stratification with the Effective Heat Source (EHS) model and the Effective Momentum Source (EMS) model. We use POOLEX/PPOOLEX experiment (Lappeenranta University of Technology in Finland), in order to (a) quantify errors due to GOTHIC
DEFF Research Database (Denmark)
Andreasen, Søren Juhl
2009-01-01
Degradation phenomena in HTPEM fuel cells for use in CHP systems were investigated experimentally and by modelling. It was found that the two main degradation mechanisms in HTPEM fuel cells are carbon corrosion and Pt agglomeration. On basis of this conclusion a mechanistic model, describing...... the degradation caused by these phenomena, is suggested. Using the proposed model, information about optimum operational temperatures is derived. To investigate how the degradation propagates on stack level, a simplified stack model is developed. The model is 1-dimensional, non-isothermal, and semi......-transient (considering degradation with time). The model shows that the degradation in a stack will not progress uniformly, but occurs faster in the hot end of the stack. Furthermore, the model shows that the degradation is very dependent on stack temperature control scheme. Two experiments were conducted; a 500 hours...
Aluja, Jaime Gil
2012-01-01
Little by little we are being provided with an arsenal of operative instruments of a non-numerical nature, in the shape of models and algorithms, capable of providing answers to the “aggressions” which our economics and management systems must withstand, coming from an environment full of turmoil. In the work which we are presenting, we dare to propose a set of elements from which we hope arise focuses capable of renewing those structures of economic thought which are upheld by the geometrical idea. The concepts of pretopology and topology, habitually marginalized in economics and management studies, have centred our interest in recent times. We consider that it is not possible to conceive formal structures capable of representing the Darwinism concept of economic behaviour today without recurring to this fundamental generalisation of metric spaces. In our attempts to find a solid base to the structures proposed for the treatment of economic phenomena, we have frequently resorted to the theory ...
A Model for Transport Phenomena in a Cross-Flow Ultrafiltration Module with Microchannels
Directory of Open Access Journals (Sweden)
Shiro Yoshikawa
2010-12-01
Full Text Available Cross-flow ultrafiltration of macromolecular solutions in a module with microchannels is expected to have the advantages of fast diffusion from the membrane surface and a high ratio of membrane surface area to feed liquid volume. Cross-flow ultrafiltration modules with microchannels are expected to be used for separation and refining and as membrane reactors in microchemical processes. Though these modules can be applied as a separator connected with a micro-channel reactor or a membrane reactor, there have been few papers on their performance. The purpose of this study was to clarify the relationship between operational conditions and performance of cross-flow ultrafiltration devices with microchannels. In this study, Poly Vinyl Pyrrolidone (PVP aqueous solution was used as a model solute of macromolecules such as enzymes. Cross-flow ultrafiltration experiments were carried out under constant pressure conditions, varying other operational conditions. The permeate flux decreased in the beginning of each experiment. After enough time passed, the permeate flux reached a constant value. The performance of the module was discussed based on the constant values of the flux. It was observed that the permeate flux increased with increasing transmembrane pressure (TMP and feed flow rate, and decreased with an increase of feed liquid concentration. A model of the transport phenomena in the feed liquid side channel and the permeation through the membrane was developed based on the concentration and velocity distributions in the feed side channel. The experimental results were compared with those based on the model and the performance of the ultrafiltration module is discussed.
A model for transport phenomena in a cross-flow ultrafiltration module with microchannels.
Nishimoto, Aiko; Yoshikawa, Shiro; Ookawara, Shinichi
2010-12-16
Cross-flow ultrafiltration of macromolecular solutions in a module with microchannels is expected to have the advantages of fast diffusion from the membrane surface and a high ratio of membrane surface area to feed liquid volume. Cross-flow ultrafiltration modules with microchannels are expected to be used for separation and refining and as membrane reactors in microchemical processes. Though these modules can be applied as a separator connected with a micro-channel reactor or a membrane reactor, there have been few papers on their performance. The purpose of this study was to clarify the relationship between operational conditions and performance of cross-flow ultrafiltration devices with microchannels. In this study, Poly Vinyl Pyrrolidone (PVP) aqueous solution was used as a model solute of macromolecules such as enzymes. Cross-flow ultrafiltration experiments were carried out under constant pressure conditions, varying other operational conditions. The permeate flux decreased in the beginning of each experiment. After enough time passed, the permeate flux reached a constant value. The performance of the module was discussed based on the constant values of the flux. It was observed that the permeate flux increased with increasing transmembrane pressure (TMP) and feed flow rate, and decreased with an increase of feed liquid concentration. A model of the transport phenomena in the feed liquid side channel and the permeation through the membrane was developed based on the concentration and velocity distributions in the feed side channel. The experimental results were compared with those based on the model and the performance of the ultrafiltration module is discussed.
Modellus: Learning Physics with Mathematical Modelling
Teodoro, Vitor
Computers are now a major tool in research and development in almost all scientific and technological fields. Despite recent developments, this is far from true for learning environments in schools and most undergraduate studies. This thesis proposes a framework for designing curricula where computers, and computer modelling in particular, are a major tool for learning. The framework, based on research on learning science and mathematics and on computer user interface, assumes that: 1) learning is an active process of creating meaning from representations; 2) learning takes place in a community of practice where students learn both from their own effort and from external guidance; 3) learning is a process of becoming familiar with concepts, with links between concepts, and with representations; 4) direct manipulation user interfaces allow students to explore concrete-abstract objects such as those of physics and can be used by students with minimal computer knowledge. Physics is the science of constructing models and explanations about the physical world. And mathematical models are an important type of models that are difficult for many students. These difficulties can be rooted in the fact that most students do not have an environment where they can explore functions, differential equations and iterations as primary objects that model physical phenomena--as objects-to-think-with, reifying the formal objects of physics. The framework proposes that students should be introduced to modelling in a very early stage of learning physics and mathematics, two scientific areas that must be taught in very closely related way, as they were developed since Galileo and Newton until the beginning of our century, before the rise of overspecialisation in science. At an early stage, functions are the main type of objects used to model real phenomena, such as motions. At a later stage, rates of change and equations with rates of change play an important role. This type of equations
Shah, D. B.
1984-01-01
Describes a course designed to achieve a balance between exposing students to (1) advanced topics in transport phenomena, pointing out similarities and differences between three transfer processes and (2) common methods of solving differential equations. (JN)
Mathematical interpretation of Brownian motor model: Limit cycles and directed transport phenomena
Yang, Jianqiang; Ma, Hong; Zhong, Suchuang
2018-03-01
In this article, we first suggest that the attractor of Brownian motor model is one of the reasons for the directed transport phenomenon of Brownian particle. We take the classical Smoluchowski-Feynman (SF) ratchet model as an example to investigate the relationship between limit cycles and directed transport phenomenon of the Brownian particle. We study the existence and variation rule of limit cycles of SF ratchet model at changing parameters through mathematical methods. The influences of these parameters on the directed transport phenomenon of a Brownian particle are then analyzed through numerical simulations. Reasonable mathematical explanations for the directed transport phenomenon of Brownian particle in SF ratchet model are also formulated on the basis of the existence and variation rule of the limit cycles and numerical simulations. These mathematical explanations provide a theoretical basis for applying these theories in physics, biology, chemistry, and engineering.
Mansouri, Majdi; Nounou, Mohamed N; Nounou, Hazem N
2017-09-01
In our previous work, we have demonstrated the effectiveness of the linear multiscale principal component analysis (PCA)-based moving window (MW)-generalized likelihood ratio test (GLRT) technique over the classical PCA and multiscale principal component analysis (MSPCA)-based GLRT methods. The developed fault detection algorithm provided optimal properties by maximizing the detection probability for a particular false alarm rate (FAR) with different values of windows, and however, most real systems are nonlinear, which make the linear PCA method not able to tackle the issue of non-linearity to a great extent. Thus, in this paper, first, we apply a nonlinear PCA to obtain an accurate principal component of a set of data and handle a wide range of nonlinearities using the kernel principal component analysis (KPCA) model. The KPCA is among the most popular nonlinear statistical methods. Second, we extend the MW-GLRT technique to one that utilizes exponential weights to residuals in the moving window (instead of equal weightage) as it might be able to further improve fault detection performance by reducing the FAR using exponentially weighed moving average (EWMA). The developed detection method, which is called EWMA-GLRT, provides improved properties, such as smaller missed detection and FARs and smaller average run length. The idea behind the developed EWMA-GLRT is to compute a new GLRT statistic that integrates current and previous data information in a decreasing exponential fashion giving more weight to the more recent data. This provides a more accurate estimation of the GLRT statistic and provides a stronger memory that will enable better decision making with respect to fault detection. Therefore, in this paper, a KPCA-based EWMA-GLRT method is developed and utilized in practice to improve fault detection in biological phenomena modeled by S-systems and to enhance monitoring process mean. The idea behind a KPCA-based EWMA-GLRT fault detection algorithm is to
Film models for transport phenomena with fog formation: The classical film model
Brouwers, Jos; Chesters, A.K.
1992-01-01
In the present analysis the classical film model (or film theory) is reviewed and extended. First, on the basis of a thorough analysis, the governing equations of diffusion, energy and momentum of a stagnant film are derived and solved. Subsequently, the well-known correction factors for the effect
Physics beyond the Standard Model
Valle, José W F
1991-01-01
We discuss some of the signatures associated with extensions of the Standard Model related to the neutrino and electroweak symmetry breaking sectors, with and without supersymmetry. The topics include a basic discussion of the theory of neutrino mass and the corresponding extensions of the Standard Model that incorporate massive neutrinos; an overview of the present observational status of neutrino mass searches, with emphasis on solar neutrinos, as well the as cosmological data on the amplitude of primordial density fluctuations; the implications of neutrino mass in cosmological nucleosynthesis, non-accelerator, as well as in high energy particle collider experiments. Turning to the electroweak breaking sector, we discuss the physics potential for Higgs boson searches at LEP200, including Majoron extensions of the Standard Model, and the physics of invisibly decaying Higgs bosons. We discuss the minimal supersymmetric Standard Model phenomenology, as well as some of the laboratory signatures that would be as...
Battaglia, Onofrio Rosario; Di Paola, Benedetto; Persano Adorno, Dominique; Pizzolato, Nicola; Fazio, Claudio
2017-09-01
Two 20-h modelling-based workshops focused on the explanation of thermally activated phenomena were held at the University of Palermo, Italy, during the Academic Year 2014-2015. One of them was conducted by applying an inquiry-based approach, while the other, still based on laboratory and modelling activities, was not focused on inquiry. Seventy-two students belonging to the Undergraduate Program for Chemical Engineering attended the two workshops. The related content was focused on an à la Feynman unifying approach to thermally activated phenomena. Questionnaires were administered to the students of both groups, before and post instruction. Responses were analysed using k-means cluster analysis and students' inferred lines of reasoning about the description and explanation of phenomena were studied in both groups. We find that both workshops can be considered effective in improving student's reasoning skills. However, the inquiry-based approach revealed to be more effective than the traditional one in helping students to build mechanisms of functioning and explicative models and to identify common aspects in apparently different phenomena.
Predictive modelling of edge transport phenomena in ELMy H-mode tokamak fusion plasmas
Energy Technology Data Exchange (ETDEWEB)
Loennroth, J.-S.
2009-07-01
This thesis discusses a range of work dealing with edge plasma transport in magnetically confined fusion plasmas by means of predictive transport modelling, a technique in which qualitative predictions and explanations are sought by running transport codes equipped with models for plasma transport and other relevant phenomena. The focus is on high confinement mode (H-mode) tokamak plasmas, which feature improved performance thanks to the formation of an edge transport barrier. H-mode plasmas are generally characterized by the occurrence of edge localized modes (ELMs), periodic eruptions of particles and energy, which limit confinement and may turn out to be seriously damaging in future tokamaks. The thesis introduces schemes and models for qualitative study of the ELM phenomenon in predictive transport modelling. It aims to shed new light on the dynamics of ELMs using these models. It tries to explain various experimental observations related to the performance and ELM-behaviour of H-mode plasmas. Finally, it also tries to establish more generally the potential effects of ripple-induced thermal ion losses on H-mode plasma performance and ELMs. It is demonstrated that the proposed ELM modelling schemes can qualitatively reproduce the experimental dynamics of a number of ELM regimes. Using a theory-motivated ELM model based on a linear instability model, the dynamics of combined ballooning-peeling mode ELMs is studied. It is shown that the ELMs are most often triggered by a ballooning mode instability, which renders the plasma peeling mode unstable, causing the ELM to continue in a peeling mode phase. Understanding the dynamics of ELMs will be a key issue when it comes to controlling and mitigating the ELMs in future large tokamaks. By means of integrated modelling, it is shown that an experimentally observed increase in the ELM frequency and deterioration of plasma confinement triggered by external neutral gas puffing might be due to a transition from the second to
Predictive modelling of edge transport phenomena in ELMy H-mode tokamak fusion plasmas
International Nuclear Information System (INIS)
Loennroth, J.-S.
2009-01-01
This thesis discusses a range of work dealing with edge plasma transport in magnetically confined fusion plasmas by means of predictive transport modelling, a technique in which qualitative predictions and explanations are sought by running transport codes equipped with models for plasma transport and other relevant phenomena. The focus is on high confinement mode (H-mode) tokamak plasmas, which feature improved performance thanks to the formation of an edge transport barrier. H-mode plasmas are generally characterized by the occurrence of edge localized modes (ELMs), periodic eruptions of particles and energy, which limit confinement and may turn out to be seriously damaging in future tokamaks. The thesis introduces schemes and models for qualitative study of the ELM phenomenon in predictive transport modelling. It aims to shed new light on the dynamics of ELMs using these models. It tries to explain various experimental observations related to the performance and ELM-behaviour of H-mode plasmas. Finally, it also tries to establish more generally the potential effects of ripple-induced thermal ion losses on H-mode plasma performance and ELMs. It is demonstrated that the proposed ELM modelling schemes can qualitatively reproduce the experimental dynamics of a number of ELM regimes. Using a theory-motivated ELM model based on a linear instability model, the dynamics of combined ballooning-peeling mode ELMs is studied. It is shown that the ELMs are most often triggered by a ballooning mode instability, which renders the plasma peeling mode unstable, causing the ELM to continue in a peeling mode phase. Understanding the dynamics of ELMs will be a key issue when it comes to controlling and mitigating the ELMs in future large tokamaks. By means of integrated modelling, it is shown that an experimentally observed increase in the ELM frequency and deterioration of plasma confinement triggered by external neutral gas puffing might be due to a transition from the second to
Fundamentals of Fire Phenomena
DEFF Research Database (Denmark)
Quintiere, James
analyses. Fire phenomena encompass everything about the scientific principles behind fire behaviour. Combining the principles of chemistry, physics, heat and mass transfer, and fluid dynamics necessary to understand the fundamentals of fire phenomena, this book integrates the subject into a clear...... as a visiting professor at BYG.DTU financed by the Larsen and Nielsen Foundation, and is entered to the research database by Kristian Hertz responsible for the visiting professorship....
Sotolongo-Costa, O.; Gaggero-Sager, L. M.; Becker, J. T.; Maestu, F.; Sotolongo-Grau, O.
2017-04-01
Aging associated brain decline often result in some kind of dementia. Even when this is a complex brain disorder a physical model can be used in order to describe its general behavior. A probabilistic model for the development of dementia is obtained and fitted to some experimental data obtained from the Alzheimer's Disease Neuroimaging Initiative. It is explained how dementia appears as a consequence of aging and why it is irreversible.
Accelerator physics and modeling: Proceedings
Energy Technology Data Exchange (ETDEWEB)
Parsa, Z. [ed.
1991-12-31
This report contains papers on the following topics: Physics of high brightness beams; radio frequency beam conditioner for fast-wave free-electron generators of coherent radiation; wake-field and space-charge effects on high brightness beams. Calculations and measured results for BNL-ATF; non-linear orbit theory and accelerator design; general problems of modeling for accelerators; development and application of dispersive soft ferrite models for time-domain simulation; and bunch lengthening in the SLC damping rings.
Accelerator physics and modeling: Proceedings
Energy Technology Data Exchange (ETDEWEB)
Parsa, Z. (ed.)
1991-01-01
This report contains papers on the following topics: Physics of high brightness beams; radio frequency beam conditioner for fast-wave free-electron generators of coherent radiation; wake-field and space-charge effects on high brightness beams. Calculations and measured results for BNL-ATF; non-linear orbit theory and accelerator design; general problems of modeling for accelerators; development and application of dispersive soft ferrite models for time-domain simulation; and bunch lengthening in the SLC damping rings.
Wave Generation in Physical Models
DEFF Research Database (Denmark)
Andersen, Thomas Lykke; Frigaard, Peter
The present book describes the most important aspects of wave generation techniques in physical models. Moreover, the book serves as technical documentation for the wave generation software AwaSys 6, cf. Aalborg University (2012). In addition to the two main authors also Tue Hald and Michael...
Mezzasalma, Stefano A.
1997-06-01
A general thermodynamic-electrochemical model, supported by an experimental titration procedure, is proposed to determine the number of solid aggregates of a polydispersed (and/or colloidal) system in a liquid medium subject to simultaneous agglomeration phenomena and adsorption of H+ and/or OH- ions from solution and endowed with an interparticle potential which is not strongly attractive. In a previous work [D. Beruto, S. Mezzasalma, and D. Baldovino, J. Chem. Soc. Faraday Trans. 2 91, 323 (1995)] adsorptions of protons and/or oxidryles onto the solid surfaces of monomodal silicon nitride aqueous dispersions were obtained by titration measurements made with a metal-oxide-semiconductor ion-sensitive field-effect transistor pH-meter device and employed to obtain the number of solid aggregates from the thermodynamic equilibrium state of the slurries, derived from the total Gibbs function. More generally, to apply the same titration procedure to liquid dispersions involving many solid phases, it is shown here that a simple partition criterion can be defined to obtain the experimental adsorption data related to each solid phase of the polydispersed system. Theoretically, the equilibrium state is achieved from the total Gibbs free function of the slurries with respect to each single solid aggregate species and to the ``mixed'' aggregates, containing all solid phases. To this end, following the Derjaguin-Landau-Verwey-Overbeek theory, Coulombic charge-charge interactions and dispersion-force effects, other than general multipole contributions among mixed clusters, are considered as not too strong perturbations of the ideal Gibbs free energy. By inserting the titration data in the physico-chemical condition theoretically derived, it is possible to obtain all numbers of solid aggregates as a function of the electrolyte concentration (pH) in the liquid solution.
Development of the physical model
International Nuclear Information System (INIS)
Liu Zunqi; Morsy, Samir
2001-01-01
Full text: The Physical Model was developed during Program 93+2 as a technical tool to aid enhanced information analysis and now is an integrated part of the Department's on-going State evaluation process. This paper will describe the concept of the Physical Model, including its objectives, overall structure and the development of indicators with designated strengths, followed by a brief description of using the Physical Model in implementing the enhanced information analysis. The work plan for expansion and update of the Physical Model is also presented at the end of the paper. The development of the Physical Model is an attempt to identify, describe and characterize every known process for carrying out each step necessary for the acquisition of weapons-usable material, i.e., all plausible acquisition paths for highly enriched uranium (HEU) and separated plutonium (Pu). The overall structure of the Physical Model has a multilevel arrangement. It includes at the top level all the main steps (technologies) that may be involved in the nuclear fuel cycle from the source material production up to the acquisition of weapons-usable material, and then beyond the civilian fuel cycle to the development of nuclear explosive devices (weaponization). Each step is logically interconnected with the preceding and/or succeeding steps by nuclear material flows. It contains at its lower levels every known process that is associated with the fuel cycle activities presented at the top level. For example, uranium enrichment is broken down into three branches at the second level, i.e., enrichment of UF 6 , UCl 4 and U-metal respectively; and then further broken down at the third level into nine processes: gaseous diffusion, gas centrifuge, aerodynamic, electromagnetic, molecular laser (MLIS), atomic vapor laser (AVLIS), chemical exchange, ion exchange and plasma. Narratives are presented at each level, beginning with a general process description then proceeding with detailed
Current status of models for transient phenomena in dopant diffusion and activation
International Nuclear Information System (INIS)
Pichler, P.; Stiebel, D.
2002-01-01
Transient phenomena caused by ion-implantation processes have been studied for more than 25 years now with a continuously increasing number of research articles published in this field per year. One driving force of this research is the ongoing miniaturization of ULSI MOS and bipolar technology which uses extensively the capabilities of technology-computer-aided-design (TCAD). The other driving force which attracts also academic institutions and research institutes is the high complexity of the phenomena, involving the interaction of dopants, intrinsic point defects, extended defects and impurities like carbon as well as the interactions of mobile defects with surfaces and interfaces and their redistribution in multilayer structures. This paper outlines some recent advances towards a quantitative description of such phenomena
Thermal modeling: at the crossroads of several subjects of physics
International Nuclear Information System (INIS)
1997-01-01
The modeling of thermal phenomena is of prime importance for the dimensioning of industrial facilities. However, the understanding of thermal processes requires to refer to other subjects of physics like electromagnetism, matter transformation, fluid mechanics, chemistry etc.. The aim of this workshop organized by the industrial electro-thermal engineering section of the French society of thermal engineers is to take stock of current or forthcoming advances in the coupling of thermal engineering codes with electromagnetic, fluid mechanics, chemical and mechanical engineering codes. The modeling of phenomena remains the essential link between the laboratory research of new processes and their industrial developments. From the 9 talks given during this workshop, 2 of them deal with thermal processes in nuclear reactors and fall into the INIS scope and the others concern the modeling of industrial heating or electrical processes and were selected for ETDE. (J.S.)
Anomalous transport phenomena in Weyl metal beyond the Drude model for Landauʼs Fermi liquids
Kim, Ki-Seok; Kim, Heon-Jung; Sasaki, M.; Wang, J.-F.; Li, L.
2014-12-01
Landau's Fermi-liquid theory is the standard model for metals, characterized by the existence of electron quasiparticles near a Fermi surface as long as Landau's interaction parameters lie below critical values for instabilities. Recently this fundamental paradigm has been challenged by the physics of strong spin-orbit coupling, although the concept of electron quasiparticles remains valid near the Fermi surface, where Landau's Fermi-liquid theory fails to describe the electromagnetic properties of this novel metallic state, referred to as Weyl metal. A novel ingredient is that such a Fermi surface encloses a Weyl point with definite chirality, referred to as a chiral Fermi surface, which can arise from breaking of either time reversal or inversion symmetry in systems with strong spin-orbit coupling, responsible for both the Berry curvature and the chiral anomaly. As a result, electromagnetic properties of the Weyl metallic state are described not by conventional Maxwell equations but by axion electrodynamics, where Maxwell equations are modified with a topological-in-origin spatially modulated θ ({\\boldsymbol{r}} ){\\boldsymbol{E}} \\cdot {\\boldsymbol{B}} term. This novel metallic state was realized recently in Bi1-xSbx around x˜ 3% under magnetic fields, where the Dirac spectrum appears around the critical point between the normal semiconducting (x\\lt 3%) and topological semiconducting phases (x\\gt 3%) and the time reversal symmetry breaking perturbation causes the Dirac point to split into a pair of Weyl points along the direction of the applied magnetic field for a very strong spin-orbit coupled system. In this review article, we discuss how the topological structure of both the Berry curvature and the chiral anomaly (axion electrodynamics) gives rise to anomalous transport phenomena in B{{i}1-x}Sbx around x˜ 3% under magnetic fields, thus modifying the Drude model of Landau's Fermi liquids.
Energy Technology Data Exchange (ETDEWEB)
Santhanagopalan, Shriram [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Smith, Kandler A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Graf, Peter A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Pesaran, Ahmad A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Zhang, Chao [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Lamb, Joshua [Sandia National Laboratories; Abraham, Daniel [Argonne National Laboratory; Dees, Dennis [Argonne National Laboratory; Yao, Pierre [Argonne National Laboratory
2017-08-08
NREL's Energy Storage team is exploring the effect of mechanical crush of lithium ion cells on their thermal and electrical safety. PHEV cells, fresh as well as ones aged over 8 months under different temperatures, voltage windows, and charging rates, were subjected to destructive physical analysis. Constitutive relationship and failure criteria were developed for the electrodes, separator as well as packaging material. The mechanical models capture well, the various modes of failure across different cell components. Cell level validation is being conducted by Sandia National Laboratories.
2013-01-01
This book consists of twenty seven chapters, which can be divided into three large categories: articles with the focus on the mathematical treatment of non-linear problems, including the methodologies, algorithms and properties of analytical and numerical solutions to particular non-linear problems; theoretical and computational studies dedicated to the physics and chemistry of non-linear micro-and nano-scale systems, including molecular clusters, nano-particles and nano-composites; and, papers focused on non-linear processes in medico-biological systems, including mathematical models of ferments, amino acids, blood fluids and polynucleic chains.
Instream Physical Habitat Modelling Types
DEFF Research Database (Denmark)
Conallin, John; Boegh, Eva; Krogsgaard, Jørgen
2010-01-01
The introduction of the EU Water Framework Directive (WFD) is providing member state water resource managers with significant challenges in relation to meeting the deadline for 'Good Ecological Status' by 2015. Overall, instream physical habitat modelling approaches have advantages...... and disadvantages as management tools for member states in relation to the requirements of the WFD, but due to their different model structures they are distinct in their data needs, transferability, user-friendliness and presentable outputs. Water resource managers need information on what approaches will best...... management tools, but require large amounts of data and the model structure is complex. It is concluded that the use of habitat suitability indices (HSIs) and fuzzy rules in hydraulic-habitat modelling are the most ready model types to satisfy WFD demands. These models are well documented, transferable, user...
AN INTEGRATED COMPUTER-AIDED APPROACH FOR MODELING DISINTEGRATION-RELATED PHENOMENA
CARAMELLA, C.; FERRARI, F.; RONCHI, M.; Smilde, A. K.
1990-01-01
Two phenomena have frequently been related to tablet disintegration: water uptake and disintegrating force development. The combination of these two measures allowed a step forward to understanding disintegration mechanisms. In the present work, multiple linear regression analysis was used to relate
Physical models of cell motility
2016-01-01
This book surveys the most recent advances in physics-inspired cell movement models. This synergetic, cross-disciplinary effort to increase the fidelity of computational algorithms will lead to a better understanding of the complex biomechanics of cell movement, and stimulate progress in research on related active matter systems, from suspensions of bacteria and synthetic swimmers to cell tissues and cytoskeleton.Cell motility and collective motion are among the most important themes in biology and statistical physics of out-of-equilibrium systems, and crucial for morphogenesis, wound healing, and immune response in eukaryotic organisms. It is also relevant for the development of effective treatment strategies for diseases such as cancer, and for the design of bioactive surfaces for cell sorting and manipulation. Substrate-based cell motility is, however, a very complex process as regulatory pathways and physical force generation mechanisms are intertwined. To understand the interplay between adhesion, force ...
Understanding and modelling Neo-proterozoic glaciations and their associated phenomena
International Nuclear Information System (INIS)
Le Hir, Guillaume
2007-01-01
The objective of this research thesis is to provide a consistent image of extreme glaciations which occurred during the Neo-proterozoic era. By using climate and carbon cycle models (or model of bio-geochemical cycles), the author aims at answering various scientific questions raised by the Snowball Earth hypothesis. After a description of the main geological features which characterize the Proterozoic, scientific problems are presented. The author then reports the study of carbon cycle during glaciation in order to understand its operation. Based on this constraint, a consistent scenario of exit from glaciation is defined. The physical-chemical evolution of the ocean during and after a global glaciation is then quantified in order to assess its potential effects on the environment and on the Precambrian biosphere. The last part focuses on the post-glacial evolution to establish the delay for a return to equilibrium of climate after such an extreme event [fr
cDF Theory Software for mesoscopic modeling of equilibrium and transport phenomena
Energy Technology Data Exchange (ETDEWEB)
2015-12-01
The approach is based on classical Density Functional Theory ((cDFT) coupled with the Poisson-Nernst-Planck (PNP) transport kinetics model and quantum mechanical description of short-range interaction and elementary transport processes. The model we proposed and implemented is fully atomistic, taking into account pairwise short-range and manybody long-range interactions. But in contrast to standard molecular dynamics (MD) simulations, where long-range manybody interactions are evaluated as a sum of pair-wise atom-atom contributions, we include them analytically based on wellestablished theories of electrostatic and excluded volume interactions in multicomponent systems. This feature of the PNP/cDFT approach allows us to reach well beyond the length-scales accessible to MD simulations, while retaining the essential physics of interatomic interactions from first principles and in a parameter-free fashion.
Mathematical Modeling of Transport Phenomena in Polymer Electrolyte and Direct Methanol Fuel Cells
Energy Technology Data Exchange (ETDEWEB)
Birgersson, Erik
2004-02-01
This thesis deals with modeling of two types of fuel cells: the polymer electrolyte fuel cell (PEFC) and the direct methanol fuel cell (DMFC), for which we address four major issues: a) mass transport limitations; b) water management (PEFC); c) gas management (DMFC); d) thermal management. Four models have been derived and studied for the PEFC, focusing on the cathode. The first exploits the slenderness of the cathode for a two-dimensional geometry, leading to a reduced model, where several non dimensional parameters capture the behavior of the cathode. The model was extended to three dimensions, where four different flow distributors were studied for the cathode. A quantitative comparison shows that the interdigitated channels can sustain the highest current densities. These two models, comprising isothermal gas phase flow, limit the studies to (a). Returning to a two-dimensional geometry of the PEFC, the liquid phase was introduced via a separate flow model approach for the cathode. In addition to conservation of mass, momentum and species, the model was extended to consider simultaneous charge and heat transfer for the whole cell. Different thermal, flow fields, and hydrodynamic conditions were studied, addressing (a), (b) and (d). A scale analysis allowed for predictions of the cell performance prior to any computations. Good agreement between experiments with a segmented cell and the model was obtained. A liquid-phase model, comprising conservation of mass, momentum and species, was derived and analyzed for the anode of the DMFC. The impact of hydrodynamic, electrochemical and geometrical features on the fuel cell performance were studied, mainly focusing on (a). The slenderness of the anode allows the use of a narrow-gap approximation, leading to a reduced model, with benefits such as reduced computational cost and understanding of the physical trends prior to any numerical computations. Adding the gas-phase via a multiphase mixture approach, the gas
International Nuclear Information System (INIS)
Hinchliffe, I.
1996-12-01
The Standard Model of particle physics has been very successful in describing experimental data with great precision. With the exception of some neutrino anomalies, there is no data that is in disagreement with it. Nevertheless, the model is regarded as incomplete and unsatisfactory. There is no explanation of the pattern of quark and lepton masses and, possibly more important, no understanding of the scale of electroweak interactions. Electroweak symmetry breaking is implemented in the Standard Model from the presence of a scalar electroweak doublet, the Higgs field, that acquires a vacuum expectation value of order 250 GeV and leaves as a remnant one physical state, the electrically neutral Higgs boson whose mass is not predicted. In this talk, the author compares the techniques used at, and capabilities of, various facilities in searching for new phenomena. The author emphasizes the cases where information from more than one facility may be needed to fully explore the physics
Modeling of condensation, stratification, and mixing phenomena in a pool of water
International Nuclear Information System (INIS)
Li, H.; Kudinov, P.; Villanueva, W.
2010-12-01
This work pertains to the research program on Containment Thermal-Hydraulics at KTH. The objective is to evaluate and improve performance of methods, which are used to analyze thermal-hydraulics of steam suppression pools in a BWR plant under different abnormal transient and accident conditions. As a passive safety system, the function of steam pressure suppression pools is paramount to the containment performance. In the present work, the focus is on apparently-benign but intricate and potentially risk-significant scenarios in which thermal stratification could significantly impede the pool's pressure suppression capacity. For the case of small flow rates of steam influx, the steam condenses rapidly in the pool and the hot condensate rises in a narrow plume above the steam injection plane and spreads into a thin layer at the pool's free surface. When the steam flow rate increases significantly, momentum introduced by the steam injection and/or periodic expansion and shrink of large steam bubbles due to direct contact condensation can cause breakdown of the stratified layers and lead to mixing of the pool water. Accurate prediction of the pool thermal-hydraulics in such scenarios presents a computational challenge. Lumped-parameter models have no capability to predict temperature distribution of water pool during thermal stratification development. While high-order-accurate CFD (RANS, LES) methods are not practical due to excessive computing power needed to calculate 3D high-Rayleighnumber natural circulation flow in long transients. In the present work, a middleground approach is used, namely CFD-like model of the general purpose thermalhydraulic code GOTHIC. Each cell of 3D GOTHIC grid uses lumped parameter volume type closures for modeling of various heat and mass transfer processes at subgrid scale. We use GOTHIC to simulate POOLEX/PPOOLEX experiment, in order to (a) quantify errors due to GOTHIC's physical models and numerical schemes, and (b) propose
Mathematical modelling of transport phenomena in radioactive waste-cement-bentonite matrix
International Nuclear Information System (INIS)
Plecas, Ilija; Dimovic, Slavko
2010-01-01
Document available in extended abstract form only. The leaching rate of 137 Cs from spent mix bead (anion and cation) exchange resins in a cement-bentonite matrix has been studied. Transport phenomena involved in the leaching of a radioactive material from a cement-bentonite matrix are investigated using three methods based on theoretical equations. These are: the diffusion equation for a plane source an equation for diffusion coupled to a first-order equation and an empirical method employing a polynomial equation. The results presented in this paper are from a 25-year mortar and concrete testing project that will influence the design choices for radioactive waste packaging for a future Serbian radioactive waste disposal center. Radioactive waste is waste material containing radioactive chemical elements which does not have a practical purpose. It is often the product of a nuclear process, such as nuclear fission. Waste can also be generated from the processing of fuel for nuclear reactors or nuclear weapons. The main objective in managing and disposing of radioactive (or other) waste is to protect people and the environment. This means isolating or diluting the waste so that the rate or concentration of any radionuclides returned to the biosphere is harmless. Storage as the placement of waste in a nuclear facility where isolation, environmental protection and human control are provided with the intent that the waste will be retrieved at a later time. Disposal as the emplacement of waste in an approved, specified facility (e.g. near surface or geological repository) without the intention of retrieval. The processing of radioactive wastes may be done for economic reasons (e.g. to reduce the volume for storage or disposal, or to recover a 'resource' from the waste), or safety reasons (e.g. converting the waste to a more 'stable' form, such as one that will contain the radionuclide inventory for a long time). Typically processing involves reducing
Physics beyond the standard model
Energy Technology Data Exchange (ETDEWEB)
Valle, J.W.F. [Valencia Univ. (Spain). Dept. de Fisica Teorica]. E-mail: valle@flamenco.uv.es
1996-07-01
We discuss some of the signatures associated with extensions of the Standard Model related to the neutrino and electroweak symmetry breaking sectors, with and without supersymmetry. The topics include a basic discussion of the theory of neutrino mass and the corresponding extensions of the Standard Model that incorporate massive neutrinos; an overview of the present observational status of neutrino mass searches, with emphasis on solar neutrinos, as well as cosmological data on the amplitude of primordial density fluctuations; the implications of neutrino mass in cosmological nucleosynthesis, non-accelerator, as well as in high energy particle collider experiments. Turning to the electroweak breaking sector, we discuss the physics potential for Higgs boson searches at LEP200, including Majorana extensions of the Standard Model, and the physics of invisibly decaying Higgs bosons. We discuss the minimal supersymmetric Standard Model phenomenology, as well as some of the laboratory signatures that would be associated to models with R parity violation, especially in Z and scalar boson decays. (author)
The numerical modelling of mixing phenomena of nanofluids in passive micromixers
Milotin, R.; Lelea, D.
2018-01-01
The paper deals with the rapid mixing phenomena in micro-mixing devices with four tangential injections and converging tube, considering nanoparticles and water as the base fluid. Several parameters like Reynolds number (Re = 6 – 284) or fluid temperature are considered in order to optimize the process and obtain fundamental insight in mixing phenomena. The set of partial differential equations is considered based on conservation of momentum and species. Commercial package software Ansys-Fluent is used for solution of differential equations, based on a finite volume method. The results reveal that mixing index and mixing process is strongly dependent both on Reynolds number and heat flux. Moreover there is a certain Reynolds number when flow instabilities are generated that intensify the mixing process due to the tangential injections of the fluids.
Prediction and Uncertainty in Computational Modeling of Complex Phenomena: A Whitepaper
Energy Technology Data Exchange (ETDEWEB)
Trucano, T.G.
1999-01-20
This report summarizes some challenges associated with the use of computational science to predict the behavior of complex phenomena. As such, the document is a compendium of ideas that have been generated by various staff at Sandia. The report emphasizes key components of the use of computational to predict complex phenomena, including computational complexity and correctness of implementations, the nature of the comparison with data, the importance of uncertainty quantification in comprehending what the prediction is telling us, and the role of risk in making and using computational predictions. Both broad and more narrowly focused technical recommendations for research are given. Several computational problems are summarized that help to illustrate the issues we have emphasized. The tone of the report is informal, with virtually no mathematics. However, we have attempted to provide a useful bibliography that would assist the interested reader in pursuing the content of this report in greater depth.
Hasanah, Nur
2012-01-01
ome scientist had made an evidence to proof the relationship between lunar phase and meteorological phenomena in their own area. Here we also did the assignment statistically in the case of Makassar City, Indonesia. We were using official meteorologist data, such as rainfall, clouds, and temperature, covering a period 28 years from January 1984 to December 2011. The statistical analyses were done using discriminant analysis and persistence. Further, we tested the result with cross validation ...
International Nuclear Information System (INIS)
Smith, Curtis L.; Prescott, Steven; Kvarfordt, Kellie; Sampath, Ram; Larson, Katie
2015-01-01
Early in 2013, researchers at the Idaho National Laboratory outlined a technical framework to support the implementation of state-of-the-art probabilistic risk assessment to predict the safety performance of advanced small modular reactors. From that vision of the advanced framework for risk analysis, specific tasks have been underway in order to implement the framework. This report discusses the current development of a several tasks related to the framework implementation, including a discussion of a 3D physics engine that represents the motion of objects (including collision and debris modeling), cloud-based analysis tools such as a Bayesian-inference engine, and scenario simulations. These tasks were performed during 2015 as part of the technical work associated with the Advanced Reactor Technologies Program.
Energy Technology Data Exchange (ETDEWEB)
Smith, Curtis L. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Prescott, Steven [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kvarfordt, Kellie [Idaho National Lab. (INL), Idaho Falls, ID (United States); Sampath, Ram [Idaho National Lab. (INL), Idaho Falls, ID (United States); Larson, Katie [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2015-09-01
Early in 2013, researchers at the Idaho National Laboratory outlined a technical framework to support the implementation of state-of-the-art probabilistic risk assessment to predict the safety performance of advanced small modular reactors. From that vision of the advanced framework for risk analysis, specific tasks have been underway in order to implement the framework. This report discusses the current development of a several tasks related to the framework implementation, including a discussion of a 3D physics engine that represents the motion of objects (including collision and debris modeling), cloud-based analysis tools such as a Bayesian-inference engine, and scenario simulations. These tasks were performed during 2015 as part of the technical work associated with the Advanced Reactor Technologies Program.
A three-dimensional mixed-domain PEM fuel cell model with fully-coupled transport phenomena
Energy Technology Data Exchange (ETDEWEB)
Meng, Hua [Center for Engineering and Scientific Computation, College of Computer Science, P.O. Box 1455, Zhejiang University, Hangzhou, Zhejiang 310027 (China)
2007-02-10
A three-dimensional mixed-domain PEM fuel cell model with fully-coupled transport phenomena has been developed in this paper. In this model, after fully justified simplifications, only one set of interfacial boundary conditions is required to connect the water content equation inside the membrane and the equation of the water mass fraction in the other regions. All the other conservation equations are still solved in the single-domain framework. Numerical results indicate that although the fully-coupled transport phenomena produce only minor effects on the overall PEM fuel cell performance, i.e. average current density, they impose significant effects on current distribution, net water transfer coefficient, velocity and density variations, and species distributions. Intricate interactions of the mass transfer across the membrane, electrochemical kinetics, density and velocity variations, and species distributions dictate the detailed cell performances. Therefore, for accurate PEM fuel cell modeling and simulation, the effects of the fully-coupled transport phenomena could not be neglected. (author)
Directory of Open Access Journals (Sweden)
Zheng Miao
2014-04-01
Full Text Available The transport phenomena in a passive direct methanol fuel cell (DMFC were numerically simulated by the proposed two-dimensional two-phase nonisothermal mass transport model. The anisotropic transport characteristic and deformation of the gas diffusion layer (GDL were considered in this model. The natural convection boundary conditions were adopted for the transport of methanol, oxygen, and heat at the GDL outer surface. The effect of methanol concentration in the reservoir on cell performance was examined. The distribution of multiphysical fields in the membrane electrode assembly (MEA, especially in the catalyst layers (CLs, was obtained and analyzed. The results indicated that transport resistance for the methanol mainly existed in the MEA while that for oxygen and heat was primarily due to natural convection at the GDL outer surface. Because of the relatively high methanol concentration, the local reaction rate in CLs was mainly determined by the overpotential. Methanol concentration between 3 M and 4 M was recommended for passive liquid feed DMFC in order to achieve a balance between the cell performance and the methanol crossover.
International Nuclear Information System (INIS)
1984-08-01
The MELCOR project is developing a new generation of risk assessment computer programs for analysis of severe accidents at nuclear power plants. This document details the findings in the thermal-hydraulic areas for PWRs and areas common to both PWRs and BWRs. The study was performed by specialists from each of the various nuclear plant design or analysis areas where thermal-hydraulics is important. The study found that the current level of thermal-hydraulic modeling that exists for performing risk assessments is typified by the modeling in the MARCH code. This level of modeling was found to be inadequate for MELCOR because of inconsistent or nonexistent modeling of important phenomena, particularly invessel phenomena, systems, and structures. Pressurized water reactor modeling was found to be more complete than modeling for boiling water reactor designs, particularly in containment. Finally, although reactor cavity modeling was considered essential for risk assessments, the lack of adequate modeling found for the cavity was identified as a serious impediment to the development of second-generation risk codes
Cabin Environment Physics Risk Model
Mattenberger, Christopher J.; Mathias, Donovan Leigh
2014-01-01
This paper presents a Cabin Environment Physics Risk (CEPR) model that predicts the time for an initial failure of Environmental Control and Life Support System (ECLSS) functionality to propagate into a hazardous environment and trigger a loss-of-crew (LOC) event. This physics-of failure model allows a probabilistic risk assessment of a crewed spacecraft to account for the cabin environment, which can serve as a buffer to protect the crew during an abort from orbit and ultimately enable a safe return. The results of the CEPR model replace the assumption that failure of the crew critical ECLSS functionality causes LOC instantly, and provide a more accurate representation of the spacecraft's risk posture. The instant-LOC assumption is shown to be excessively conservative and, moreover, can impact the relative risk drivers identified for the spacecraft. This, in turn, could lead the design team to allocate mass for equipment to reduce overly conservative risk estimates in a suboptimal configuration, which inherently increases the overall risk to the crew. For example, available mass could be poorly used to add redundant ECLSS components that have a negligible benefit but appear to make the vehicle safer due to poor assumptions about the propagation time of ECLSS failures.
Modeling of condensation, stratification, and mixing phenomena in a pool of water
Energy Technology Data Exchange (ETDEWEB)
Li, H.; Kudinov, P.; Villanueva, W. (Royal Institute of Technology (KTH). Div. of Nuclear Power Safety, Stockholm (Sweden))
2010-12-15
This work pertains to the research program on Containment Thermal-Hydraulics at KTH. The objective is to evaluate and improve performance of methods, which are used to analyze thermal-hydraulics of steam suppression pools in a BWR plant under different abnormal transient and accident conditions. As a passive safety system, the function of steam pressure suppression pools is paramount to the containment performance. In the present work, the focus is on apparently-benign but intricate and potentially risk-significant scenarios in which thermal stratification could significantly impede the pool's pressure suppression capacity. For the case of small flow rates of steam influx, the steam condenses rapidly in the pool and the hot condensate rises in a narrow plume above the steam injection plane and spreads into a thin layer at the pool's free surface. When the steam flow rate increases significantly, momentum introduced by the steam injection and/or periodic expansion and shrink of large steam bubbles due to direct contact condensation can cause breakdown of the stratified layers and lead to mixing of the pool water. Accurate prediction of the pool thermal-hydraulics in such scenarios presents a computational challenge. Lumped-parameter models have no capability to predict temperature distribution of water pool during thermal stratification development. While high-order-accurate CFD (RANS, LES) methods are not practical due to excessive computing power needed to calculate 3D high-Rayleighnumber natural circulation flow in long transients. In the present work, a middleground approach is used, namely CFD-like model of the general purpose thermalhydraulic code GOTHIC. Each cell of 3D GOTHIC grid uses lumped parameter volume type closures for modeling of various heat and mass transfer processes at subgrid scale. We use GOTHIC to simulate POOLEX/PPOOLEX experiment, in order to (a) quantify errors due to GOTHIC's physical models and numerical schemes, and (b
Modelling high frequency phenomena in the rotor of induction motors under no-load test conditions
International Nuclear Information System (INIS)
Boglietti, Aldo; Bottauscio, Oriano.; Chiampi, Mario; Lazzari, Mario
2003-01-01
The paper aims to deep the electromagnetic phenomena in the rotor of induction motors produced during the no-load test by the high-order harmonics of the spatial distribution of magnetic flux. The analysis is carried out by a flux driven finite element procedure, which can take into account the hysteresis of magnetic material, the induced currents in rotor cage and the eddy currents in the laminations. The computed results, including losses and local waveforms of electrical and magnetic quantities, are finally discussed
Directory of Open Access Journals (Sweden)
J. Heger
2004-01-01
Full Text Available A finite element method algorithm is presented that enables numerical simulation of real phenomena that take place during an industrial process of continuous casting of steel. The algorithm takes into account all known kinds of nonlinearities: material nonlinearity connected to the nonlinear temperature dependence of material properties, large deformations from the process of material forming and contacts between the slab and rollers of the strand. Received results describe the sensitivity of the product to crack initiation, not only during the process of continuous casting itself but also in the finished and cooled slab.
Transport phenomena in multiphase flows
Mauri, Roberto
2015-01-01
This textbook provides a thorough presentation of the phenomena related to the transport of mass, momentum and energy. It lays all the basic physical principles, then for the more advanced readers, it offers an in-depth treatment with advanced mathematical derivations and ends with some useful applications of the models and equations in specific settings. The important idea behind the book is to unify all types of transport phenomena, describing them within a common framework in terms of cause and effect, respectively represented by the driving force and the flux of the transported quantity. The approach and presentation are original in that the book starts with a general description of transport processes, providing the macroscopic balance relations of fluid dynamics and heat and mass transfer, before diving into the mathematical realm of continuum mechanics to derive the microscopic governing equations at the microscopic level. The book is a modular teaching tool and can be used either for an introductory...
Fundamentals of wave phenomena
Hirose, Akira
2010-01-01
This textbook provides a unified treatment of waves that either occur naturally or can be excited and propagated in various media. This includes both longitudinal and transverse waves. The book covers both mechanical and electrical waves, which are normally covered separately due to their differences in physical phenomena.
Excellence in Physics Education Award: Modeling Theory for Physics Instruction
Hestenes, David
2014-03-01
All humans create mental models to plan and guide their interactions with the physical world. Science has greatly refined and extended this ability by creating and validating formal scientific models of physical things and processes. Research in physics education has found that mental models created from everyday experience are largely incompatible with scientific models. This suggests that the fundamental problem in learning and understanding science is coordinating mental models with scientific models. Modeling Theory has drawn on resources of cognitive science to work out extensive implications of this suggestion and guide development of an approach to science pedagogy and curriculum design called Modeling Instruction. Modeling Instruction has been widely applied to high school physics and, more recently, to chemistry and biology, with noteworthy results.
Physics at a 100 TeV pp Collider: Standard Model Processes
Energy Technology Data Exchange (ETDEWEB)
Mangano, M. L. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Zanderighi, G. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Aguilar Saavedra, J. A. [Univ. of Granada (Spain); Alekhin, S. [Univ. of Hamburg (Germany). Inst. for Theoretical Physics; Inst. for High Energy Physics (IHEP), Moscow (Russian Federation); Badger, S. [Univ. of Edinburgh, Scotland (United Kingdom); Bauer, C. W. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Becher, T. [Univ. Bern (Switzerland); Bertone, V. [Univ. of Oxford (United Kingdom); Bonvini, M. [Univ. of Oxford (United Kingdom); Boselli, S. [Univ. of Pavia (Italy); Bothmann, E. [Gottingen Univ. (Germany); Boughezal, R. [Argonne National Lab. (ANL), Argonne, IL (United States); Cacciari, M. [Univ. Paris Diderot (France); Sorbonne Univ., Paris (France); Carloni Calame, C M. [Istituto Nazionale di Fisica Nucleare (INFN), Pavia (Italy); Caola, F. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Campbell, J. M. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Carrazza, S. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Chiesa, M. [Istituto Nazionale di Fisica Nucleare (INFN), Pavia (Italy); Cieri, L. [Univ. of Zurich (Switzerland); Cimaglia, F. [Univ. degli Studi di Milano (Italy); Febres Cordero, F. [Physikalisches Inst., Freiburg (Germany); Ferrarese, P. [Gottingen Univ. (Germany); D' Enterria, D. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Ferrera, G. [Univ. degli Studi di Milano (Italy); Garcia i Tormo, X. [Univ. Bern (Switzerland); Garzelli, M. V. [Univ. of Hamburg (Germany); Germann, E. [Monash Univ., Melbourne, VIC (Australia); Hirschi, V. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Han, T. [Univ. of Pittsburgh, PA (United States); Ita, H. [Physikalisches Inst., Freiburg (Germany); Jager, B. [Univ. of Tubingen (Germany); Kallweit, S. [Johannes Gutenberg Univ., Mainz (Germany); Karlberg, A. [Univ. of Oxford (United Kingdom); Kuttimalai, S. [Durham Univ. (United Kingdom); Krauss, F. [Durham Univ. (United Kingdom); Larkoski, A. J. [Harvard Univ., Cambridge, MA (United States); Lindert, J. [Univ. of Zurich (Switzerland); Luisoni, G. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Maierhofer, P. [Univ. of Freiburg (Germany); Mattelaer, O. [Durham Univ. (United Kingdom); Martinez, H. [Univ. of Pavia (Italy); Moch, S. [Univ. of Hamburg (Germany); Montagna, G. [Univ. of Pavia (Italy); Moretti, M. [Univ. of Ferrara (Italy); Nason, P. [Univ. of Milano (Italy); Nicrosini, O. [Istituto Nazionale di Fisica Nucleare (INFN), Pavia (Italy); Oleari, C. [Univ. of Milano (Italy); Pagani, D. [Univ. Catholique de Louvain (Belgium); Papaefstathiou, A. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Petriello, F. [Northwestern Univ., Evanston, IL (United States); Piccinini, F. [Istituto Nazionale di Fisica Nucleare (INFN), Pavia (Italy); Pierini, M. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Pierog, T. [Karlsruhe Inst. of Technology (KIT) (Germany); Pozzorini, S. [Univ. of Zurich (Switzerland); Re, E. [National Centre for Scientific Research (CNRS), Annecy-le-Vieux (France). Lab. of Annecy-le-Vieux for Theoretical Physics (LAPTh); Robens, T. [Technische Universitat Dresden (Germany); Rojo, J. [Univ. of Oxford (United Kingdom); Ruiz, R. [Durham Univ. (United Kingdom); Sakurai, K. [Durham Univ. (United Kingdom); Salam, G. P. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Salfelder, L. [Univ. of Tubingen (Germany); Schonherr, M. [Univ. of Ferrara (Italy); Schulze, M. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Schumann, S. [Univ. Gottingen (Germany); Selvaggi, M. [Univ. Catholique de Louvain (Belgium); Shivaji, A. [Istituto Nazionale di Fisica Nucleare (INFN), Pavia (Italy); Siodmok, A. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Polish Academy of Sciences (PAS), Krakow (Poland); Skands, P. [Monash Univ., Melbourne, VIC (Australia); Torrielli, P. [Univ. of Torino (Italy); Tramontano, F. [Univ. of Napoli (Italy); Tsinikos, I. [Univ. Catholique de Louvain (Belgium); Tweedie, B. [Univ. of Pittsburgh, PA (United States); Vicini, A. [Univ. degli Studi di Milano (Italy); Westhoff, S. [Heidelberg Univ. (Germany); Zaro, M. [Sorbonne Univ., Paris (France); Zeppenfeld, D. [Forschungszentrum Karlsruhe (Germany)
2017-06-22
This report summarises the properties of Standard Model processes at the 100 TeV pp collider. We document the production rates and typical distributions for a number of benchmark Standard Model processes, and discuss new dynamical phenomena arising at the highest energies available at this collider. We discuss the intrinsic physics interest in the measurement of these Standard Model processes, as well as their role as backgrounds for New Physics searches.
Models and structures: mathematical physics
International Nuclear Information System (INIS)
2003-01-01
This document gathers research activities along 5 main directions. 1) Quantum chaos and dynamical systems. Recent results concern the extension of the exact WKB method that has led to a host of new results on the spectrum and wave functions. Progress have also been made in the description of the wave functions of chaotic quantum systems. Renormalization has been applied to the analysis of dynamical systems. 2) Combinatorial statistical physics. We see the emergence of new techniques applied to various such combinatorial problems, from random walks to random lattices. 3) Integrability: from structures to applications. Techniques of conformal field theory and integrable model systems have been developed. Progress is still made in particular for open systems with boundary conditions, in connection to strings and branes physics. Noticeable links between integrability and exact WKB quantization to 2-dimensional disordered systems have been highlighted. New correlations of eigenvalues and better connections to integrability have been formulated for random matrices. 4) Gravities and string theories. We have developed aspects of 2-dimensional string theory with a particular emphasis on its connection to matrix models as well as non-perturbative properties of M-theory. We have also followed an alternative path known as loop quantum gravity. 5) Quantum field theory. The results obtained lately concern its foundations, in flat or curved spaces, but also applications to second-order phase transitions in statistical systems
Models and structures: mathematical physics
Energy Technology Data Exchange (ETDEWEB)
NONE
2003-07-01
This document gathers research activities along 5 main directions. 1) Quantum chaos and dynamical systems. Recent results concern the extension of the exact WKB method that has led to a host of new results on the spectrum and wave functions. Progress have also been made in the description of the wave functions of chaotic quantum systems. Renormalization has been applied to the analysis of dynamical systems. 2) Combinatorial statistical physics. We see the emergence of new techniques applied to various such combinatorial problems, from random walks to random lattices. 3) Integrability: from structures to applications. Techniques of conformal field theory and integrable model systems have been developed. Progress is still made in particular for open systems with boundary conditions, in connection to strings and branes physics. Noticeable links between integrability and exact WKB quantization to 2-dimensional disordered systems have been highlighted. New correlations of eigenvalues and better connections to integrability have been formulated for random matrices. 4) Gravities and string theories. We have developed aspects of 2-dimensional string theory with a particular emphasis on its connection to matrix models as well as non-perturbative properties of M-theory. We have also followed an alternative path known as loop quantum gravity. 5) Quantum field theory. The results obtained lately concern its foundations, in flat or curved spaces, but also applications to second-order phase transitions in statistical systems.
Tessier, Frederic
Microfluidic and nanofluidic technology is revolutionizing experimental practices in analytical chemistry, molecular biology and medicine. Indeed, the development of systems of small dimensions for the processing of fluids heralds the miniaturization of traditional, cumbersome laboratory equipment onto robust, portable and efficient microchip devices (similar to the electronic microchips found in computers). Moreover, the conjunction of scale between the smallest man-made device and the largest macromolecules evolved by Nature is fertile ground for the blooming of our knowledge about the key processes of life. In fact, the conjunction is threefold, because modern computational resources also allow us to contemplate a rather explicit modelling of physical systems between the nanoscale and the microscale. In the five articles comprising this thesis, we present the results of computer simulations that address specific questions concerning the operation of two different model systems relevant to the development of small-scale fluidic devices for the manipulation and analysis of biomolecules. First, we use a Bond-Fluctuation Monte Carlo approach to study the electrophoretic drift of macromolecules across an entropic trap array built for the length separation of long, double-stranded DNA molecules. We show that the motion of the molecules is consistent with a simple balance between electric and entropic forces, in terms of a single characteristic parameter. We also extract detailed information on polymer deformation during migration, predict the separation of topoisomers, and investigate innovative ratchet driving regimes. Secondly, we present theoretical derivations, numerical calculations and Molecular Dynamics simulation results for an electrolyte confined in a capillary of nanoscopic dimensions. In particular, we study the effectiveness of neutral grafted polymer chains in reducing the magnitude of electroosmotic flow (fluid flow induced by an external electric field
Energy Technology Data Exchange (ETDEWEB)
Checchin, Mattia [Illinois Inst. of Technology, Chicago, IL (United States)
2016-12-01
Superconducting niobium accelerating cavities are devices operating in radio-frequency and able to accelerate charged particles up to energy of tera-electron-volts. Such accelerating structures are though limited in terms of quality factor and accelerating gradient, that translates--in some cases--in higher capital costs of construction and operation of superconducting rf accelerators. Looking forward for a new generation of more affordable accelerators, the physical description of limiting mechanisms in superconducting microwave resonators is discussed. In particular, the physics behind the dissipation introduced by vortices in the superconductor, the ultimate quench limitations and the quality factor degradation mechanism after a quench are described in detail. One of the limiting factor of the quality factor is the dissipation introduced by trapped magnetic flux vortices. The radio-frequency complex response of trapped vortices in superconductors is derived by solving the motion equation for a magnetic flux line, assuming a bi-dimensional and mean free path-dependent Lorentzian-shaped pinning potential. The resulting surface resistance shows the bell-shaped trend as a function of the mean free path, in agreement with the experimental data observed. Such bell-shaped trend of the surface resistance is described in terms of the interplay of the two limiting regimes identified as pinning and flux flow regimes, for low and large mean free path values respectively. The model predicts that the dissipation regime--pinning- or flux-flow-dominated--can be tuned either by acting on the frequency or on the electron mean free path value. The effect of different configurations of pinning sites and strength on the vortex surface resistance are also discussed. Accelerating cavities are also limited by the quench of the superconductive state, which limits the maximum accelerating gradient achievable. The accelerating field limiting factor is usually associate d to the
Nuclear fuel deformation phenomena
International Nuclear Information System (INIS)
Van Brutzel, L.; Dingreville, R.; Bartel, T.J.
2015-01-01
Nuclear fuel encounters severe thermomechanical environments. Its mechanical response is profoundly influenced by an underlying heterogeneous microstructure but also inherently dependent on the temperature and stress level histories. The ability to adequately simulate the response of such microstructures, to elucidate the associated macroscopic response in such extreme environments is crucial for predicting both performance and transient fuel mechanical responses. This chapter discusses key physical phenomena and the status of current modelling techniques to evaluate and predict fuel deformations: creep, swelling, cracking and pellet-clad interaction. This chapter only deals with nuclear fuel; deformations of cladding materials are discussed elsewhere. An obvious need for a multi-physics and multi-scale approach to develop a fundamental understanding of properties of complex nuclear fuel materials is presented. The development of such advanced multi-scale mechanistic frameworks should include either an explicit (domain decomposition, homogenisation, etc.) or implicit (scaling laws, hand-shaking,...) linkage between the different time and length scales involved, in order to accurately predict the fuel thermomechanical response for a wide range of operating conditions and fuel types (including Gen-IV and TRU). (authors)
Noise stabilization effects in models of interdisciplinary physics
Spagnolo, B.; Augello, G.; Caldara, P.; Fiasconaro, A.; La Cognata, A.; Pizzolato, N.; Valenti, D.; Dubkov, A. A.; Pankratov, A. L.
2009-06-01
Metastability is a generic feature of many nonlinear systems, and the problem of the lifetime of metastable states involves fundamental aspects of nonequilibrium statistical mechanics. The investigation of noise-induced phenomena in far from equilibrium systems is one of the approaches used to understand the behaviour of physical and biological complex systems. The enhancement of the lifetime of metastable states through the noise enhanced stability effect and the role played by the resonant activation phenomenon will be discussed in models of interdisciplinary physics: (i) polymer translocation dynamics; (ii) transient regime of FitzHugh-Nagumo model; (iii) market stability in a nonlinear Heston model; (iv) dynamics of Josephson junctions; (v) metastability in a quantum bitable system.
Shamshuddin, MD.; Anwar Bég, O.; Sunder Ram, M.; Kadir, A.
2018-02-01
Non-Newtonian flows arise in numerous industrial transport processes including materials fabrication systems. Micropolar theory offers an excellent mechanism for exploring the fluid dynamics of new non-Newtonian materials which possess internal microstructure. Magnetic fields may also be used for controlling electrically-conducting polymeric flows. To explore numerical simulation of transport in rheological materials processing, in the current paper, a finite element computational solution is presented for magnetohydrodynamic, incompressible, dissipative, radiative and chemically-reacting micropolar fluid flow, heat and mass transfer adjacent to an inclined porous plate embedded in a saturated homogenous porous medium. Heat generation/absorption effects are included. Rosseland's diffusion approximation is used to describe the radiative heat flux in the energy equation. A Darcy model is employed to simulate drag effects in the porous medium. The governing transport equations are rendered into non-dimensional form under the assumption of low Reynolds number and also low magnetic Reynolds number. Using a Galerkin formulation with a weighted residual scheme, finite element solutions are presented to the boundary value problem. The influence of plate inclination, Eringen coupling number, radiation-conduction number, heat absorption/generation parameter, chemical reaction parameter, plate moving velocity parameter, magnetic parameter, thermal Grashof number, species (solutal) Grashof number, permeability parameter, Eckert number on linear velocity, micro-rotation, temperature and concentration profiles. Furthermore, the influence of selected thermo-physical parameters on friction factor, surface heat transfer and mass transfer rate is also tabulated. The finite element solutions are verified with solutions from several limiting cases in the literature. Interesting features in the flow are identified and interpreted.
Modelling of transport phenomena in 3D GMAW of thick metals with V groove
Energy Technology Data Exchange (ETDEWEB)
Hu, J [Department of Mechanical Engineering, University of Bridgeport, Bridgeport, CT 06604 (United States); Tsai, H L [Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, 1870 Miner Circle, Rolla, MO 65409 (United States)
2008-03-21
This paper analyses the dynamic process of groove filling and the resulting weld pool fluid flow in gas metal arc welding of thick metals with V groove. Filler droplets carrying mass, momentum, thermal energy and sulfur species are periodically impinged onto the workpiece. The complex transport phenomena in the weld pool, caused by the combined effect of droplet impingement, gravity, electromagnetic force, surface tension and plasma arc pressure, were investigated to determine the transient weld pool shape and distributions of velocity, temperature and sulfur species in the weld pool. It was found that the groove provides a channel which can smooth the flow in the weld pool, leading to poor mixing between the filler metal and the base metal.
Cell survivor: Modeling radiobiological phenomena with a new kind of simulation
Spencer, Melissa A.
Despite widespread societal fear of radiation, whether justified or unjustified, and whether related to medicine (e.g., CT scans) or other forms of nuclear and atomic radiation (e.g., nuclear power) there is a fundamental lack of basic understanding of radiation effects on the human body. Different types of radiation are psychologically grouped into the same general fear category irrespective of their different potential to do harm, and this fear is not balanced by their potential beneficial effects. By modeling certain types of radiation biology experiments within a game engine, it is possible to enhance the player's intuitive understanding of radiobiology, both the effects of different types of radiation as well as different environmental factors that can enhance or suppress repair. For this dissertation, a game/simulation has been developed that intends to narrow the gap between public perception and the reality of these physical processes. The building blocks of this simulation are cells, which are damaged by incident radiation, accumulating either single or double strand breaks. They grow and reproduce, and are especially vulnerable during certain phases of the cell cycle (e.g. mitosis). Two dominant damage mechanisms are modeled, along with multiple repair mechanisms, for example, double strand breaks can be repaired by either non-homologous end joining or homologous repair. The output of the developed simulation was compared to data collected in experimental studies and the simulation appears to be a valid representation of the dominant mechanisms of radiobiology, as far as can be determined within the scope of this dissertation. Cell survival curves generated from playtest data display shoulders that depend on the LET of incident radiation, and rest time restores repair capability. In addition to public outreach, the presented code can be used to aid investigators by collecting data during play that can be used as a distributed Monte Carlo simulation
Critical phenomena with renormalization group analysis of a hierarchical model of financial crashes
Wu, Tiankuang Tim
2012-01-01
Financial market models are able to help the investors foresee the risk of a financial market crash and reduce the probability of its occurrence. Modelling in financial markets is categorized into microscopic models and macroscopic models. The microscopic models study the mechanisms behind the market and their behaviour. These models assist in an understanding of the causes of financial market crashes. Macroscopic models find the disciplines and rules from the historical macroscopic data for ...
International Nuclear Information System (INIS)
Silaev, A.A.; Ryabikin, M.Yu.; Vvedenskii, N.V.
2010-01-01
Complete text of publication follows. The development of theoretical approaches to the description of strong-field phenomena caused by ultrashort laser pulses is optical for studying the interaction of atoms and molecules with intense laser fields. In this work, we address two phenomena which attract much attention and can be observed under similar experimental conditions, namely, when a gas is ionized by ultrashort laser pulse. The first phenomenon is the excitation of high-order harmonics of the driving field frequency in the electron current, which leads to the generation of vacuum ultraviolet and soft X-ray radiation, as well as the attosecond pulse production. The second phenomenon is the excitation of a quasi-dc residual current in the laser-produced plasma, which results in the generation of radiation having a frequency below the laser one, e.g., terahertz waves. We present new one-dimensional (1D) and two-dimensional (2D) quantum-mechanical models for the description of such phenomena for the case a hydrogen (H) atom, and the generalization of these models to the case of various noble-gas atoms. The shape of the electrostatic potential produced by an atomic ion is shown to influence significantly the rates of the processes in the dynamics of atomic electron, and even more, the rates of the tunneling and above-barrier ionization, which is of utmost importance for the considered phenomena. The results of solving the time-dependent Schroedinger equation with the 1D and 2D potentials, which we propose, are compared with the results of the ab initio three-dimensional calculations for the H atom. We find the regions of laser pulse parameters, where the results obtained with proposed models have much better accuracy than the results provided by the models used earlier. Acknowledgements. This work was supported by the Russian Foundation for Basic Research, the Presidential Council on Grants of the Russian Federation, the Ministry of Education and Science of the
International Nuclear Information System (INIS)
Ramirez-Argaez, M. A.; Conteras, F.; Gonzalez, C.
2006-01-01
In this work a fundamental Eulerian mathematical model was developed to study fluid flow and mixing phenomena in aluminium ladles equipped with impeller for deshidrogenization treatment. The effect of critical process parameters such as rotor speed, depth of immersion, gas flow rate, and type of rotor on the mixing behavior and vortex formation was analyzed with this model. The model simulates operation with and without gas injection and it was developed on the commercial CFD code PHOENICS 3.4 in order to solve all conservation equations governing the process, i. e. continuity, 3D turbulent Navier-Stockers and the kε turbulence model for a two-phase fluid flow problem using the Inter Phase Slip Algorithm (IPSA). (Author). 20 refs
Mayor, T S; Couto, S; Psikuta, A; Rossi, R M
2015-12-01
The ability of clothing to provide protection against external environments is critical for wearer's safety and thermal comfort. It is a function of several factors, such as external environmental conditions, clothing properties and activity level. These factors determine the characteristics of the different microclimates existing inside the clothing which, ultimately, have a key role in the transport processes occurring across clothing. As an effort to understand the effect of transport phenomena in clothing microclimates on the overall heat transport across clothing structures, a numerical approach was used to study the buoyancy-driven heat transfer across horizontal air layers trapped inside air impermeable clothing. The study included both the internal flow occurring inside the microclimate and the external flow occurring outside the clothing layer, in order to analyze the interdependency of these flows in the way heat is transported to/from the body. Two-dimensional simulations were conducted considering different values of microclimate thickness (8, 25 and 52 mm), external air temperature (10, 20 and 30 °C), external air velocity (0.5, 1 and 3 m s(-1)) and emissivity of the clothing inner surface (0.05 and 0.95), which implied Rayleigh numbers in the microclimate spanning 4 orders of magnitude (9 × 10(2)-3 × 10(5)). The convective heat transfer coefficients obtained along the clothing were found to strongly depend on the transport phenomena in the microclimate, in particular when natural convection is the most important transport mechanism. In such scenario, convective coefficients were found to vary in wavy-like manner, depending on the position of the flow vortices in the microclimate. These observations clearly differ from data in the literature for the case of air flow over flat-heated surfaces with constant temperature (which shows monotonic variations of the convective heat transfer coefficients, along the length of the surface). The flow
Mayor, T. S.; Couto, S.; Psikuta, A.; Rossi, R. M.
2015-12-01
The ability of clothing to provide protection against external environments is critical for wearer's safety and thermal comfort. It is a function of several factors, such as external environmental conditions, clothing properties and activity level. These factors determine the characteristics of the different microclimates existing inside the clothing which, ultimately, have a key role in the transport processes occurring across clothing. As an effort to understand the effect of transport phenomena in clothing microclimates on the overall heat transport across clothing structures, a numerical approach was used to study the buoyancy-driven heat transfer across horizontal air layers trapped inside air impermeable clothing. The study included both the internal flow occurring inside the microclimate and the external flow occurring outside the clothing layer, in order to analyze the interdependency of these flows in the way heat is transported to/from the body. Two-dimensional simulations were conducted considering different values of microclimate thickness (8, 25 and 52 mm), external air temperature (10, 20 and 30 °C), external air velocity (0.5, 1 and 3 m s-1) and emissivity of the clothing inner surface (0.05 and 0.95), which implied Rayleigh numbers in the microclimate spanning 4 orders of magnitude (9 × 102-3 × 105). The convective heat transfer coefficients obtained along the clothing were found to strongly depend on the transport phenomena in the microclimate, in particular when natural convection is the most important transport mechanism. In such scenario, convective coefficients were found to vary in wavy-like manner, depending on the position of the flow vortices in the microclimate. These observations clearly differ from data in the literature for the case of air flow over flat-heated surfaces with constant temperature (which shows monotonic variations of the convective heat transfer coefficients, along the length of the surface). The flow patterns and
International Nuclear Information System (INIS)
Lalleman, Sophie; Bertrand, Murielle; Plasari, Edouard
2012-01-01
Oxalic precipitation is usually applied in nuclear industry to process radioactive wastes or to recover actinides from a multicomponent solution.This paper deals with the development of methods adapted to a nuclear environment in order to study the agglomeration phenomena during actinide oxalic precipitation.These methods are previously set up with harmless elements that simulate the actinide behaviour: the lanthanides. A parametric study is carried out to quantify the influence of operating parameters on the agglomeration kernel and to determine a kinetic law for this mechanism. The experimental study is performed in a continuous-MSMPR precipitator at steady-state. The method is based on the resolution of two population balances using the moment approach, one for elementary crystals and the other for agglomerates. Provided that the kinetic rates of nucleation and growth are known, the agglomeration kernel can be obtained from a mathematical treatment of the experimental particle size distributions. Results point out that experimental crystal sizes are consistent with an independent kernel. It appears that the agglomeration kernel is directly proportional to supersaturation, increases with temperature but is limited by ionic strength and shear rate. (authors)
Statistical Analysis by Statistical Physics Model for the STOCK Markets
Wang, Tiansong; Wang, Jun; Fan, Bingli
A new stochastic stock price model of stock markets based on the contact process of the statistical physics systems is presented in this paper, where the contact model is a continuous time Markov process, one interpretation of this model is as a model for the spread of an infection. Through this model, the statistical properties of Shanghai Stock Exchange (SSE) and Shenzhen Stock Exchange (SZSE) are studied. In the present paper, the data of SSE Composite Index and the data of SZSE Component Index are analyzed, and the corresponding simulation is made by the computer computation. Further, we investigate the statistical properties, fat-tail phenomena, the power-law distributions, and the long memory of returns for these indices. The techniques of skewness-kurtosis test, Kolmogorov-Smirnov test, and R/S analysis are applied to study the fluctuation characters of the stock price returns.
PIV Experiments to Measure Flow Phenomena in a Scaled Model of a VHTR Lower Plenum
Energy Technology Data Exchange (ETDEWEB)
Hugh M. McIlroy, Jr.; Donald M. McEligot; Richard R. Schultz; Daniel Christensen; Robert J. Pink; Ryan C. Johnson
2006-09-01
A report of experimental data collected at the Matched-Index-of-Refraction (MIR) Laboratory in support of contract DE-AC07-05ID14517 and the INL Standard Problem on measurements of flow phenomena occurring in a lower plenum of a typical prismatic VHTR concept reactor to assess CFD code is presented. Background on the experimental setup and procedures is provided along with several samples of data obtained from the 3-D PIV system and an assessment of experimental uncertainty is provided. Data collected in this study include 3-dimensional velocity-field descriptions of the flow in all four inlet jets and the entire lower plenum with inlet jet Reynolds numbers (ReJet) of approximately 4300 and 12,400. These investigations have generated over 2 terabytes of data that has been processed to describe the various velocity components in formats suitable for external release and archived on removable hard disks. The processed data from both experimental studies are available in multi-column text format.
Physics modeling support contract: Final report
Energy Technology Data Exchange (ETDEWEB)
1987-09-30
This document is the final report for the Physics Modeling Support contract between TRW, Inc. and the Lawrence Livermore National Laboratory for fiscal year 1987. It consists of following projects: TIBER physics modeling and systems code development; advanced blanket modeling task; time dependent modeling; and free electron maser for TIBER II.
Physics modeling support contract: Final report
International Nuclear Information System (INIS)
1987-01-01
This document is the final report for the Physics Modeling Support contract between TRW, Inc. and the Lawrence Livermore National Laboratory for fiscal year 1987. It consists of following projects: TIBER physics modeling and systems code development; advanced blanket modeling task; time dependent modeling; and free electron maser for TIBER II
Numerical Modelling Of Thermal And Structural Phenomena In Yb:YAG Laser Butt-Welded Steel Elements
Directory of Open Access Journals (Sweden)
Kubiak M.
2015-06-01
Full Text Available The numerical model of thermal and structural phenomena is developed for the analysis of Yb:YAG laser welding process with the motion of the liquid material in the welding pool taken into account. Temperature field and melted material velocity field in the fusion zone are obtained from the numerical solution of continuum mechanics equations using Chorin projection method and finite volume method. Phase transformations in solid state are analyzed during heating and cooling using classical models of the kinetics of phase transformations as well as CTA and CCT diagrams for welded steel. The interpolated heat source model is developed in order to reliably reflect the real distribution of Yb:YAG laser power obtained by experimental research on the laser beam profile.
Opaque models: Using drugs and dreams to explore the neurobiological basis of mental phenomena.
Langlitz, Nicolas
2017-01-01
On the basis of four historical and ethnographic case studies of modeling in neuroscience laboratories, this chapter introduces a distinction between transparent and opaque models. A transparent model is a simplified representation of a real world phenomenon. If it is not patently clear, it is at least much better comprehended than its objects of representation. An opaque model, by contrast, looks at one only partially understood phenomenon to stand in for another partially understood phenomenon. Here, the model is often just as complex as its target. Examples of such opaque models discussed in this chapter are the use of hallucinogen intoxication in humans and animals as well as the dreaming brain as models of psychosis as well as the dreaming brain as a model of consciousness in general. Several functions of opaque models are discussed, ranging from the generation of funding to the formulation of new research questions. While science studies scholars have often emphasized the epistemic fertility of failures of representation, the opacity of hallucinogen intoxications and dreams seems to have diminished the potential to produce positive knowledge from the representational relationship between the supposed models and their targets. Bidirectional comparisons between inebriation, dreaming, and psychosis, however, proved to be generative on the level of basic science. Moreover, the opaque models discussed in this chapter implicated cosmologies that steered research endeavors into certain directions rather than others. © 2017 Elsevier B.V. All rights reserved.
Renormalization group and critical phenomena
International Nuclear Information System (INIS)
Ji Qing
2004-01-01
The basic clue and the main steps of renormalization group method used for the description of critical phenomena is introduced. It is pointed out that this method really reflects the most important physical features of critical phenomena, i.e. self-similarity, and set up a practical solving method from it. This way of setting up a theory according to the features of the physical system is really a good lesson for today's physicists. (author)
Towne, Dudley H
1988-01-01
This excellent undergraduate-level text emphasizes optics and acoustics, covering inductive derivation of the equation for transverse waves on a string, acoustic plane waves, boundary-value problems, polarization, three-dimensional waves and more. With numerous problems (solutions for about half). ""The material is superbly chosen and brilliantly written"" - Physics Today. Problems. Appendices.
Transport phenomena in nanofluidics
Schoch, Reto Bruno; Han, J.; Renaud, Philippe
2008-01-01
Transport of fluid in and around nanometer-sized objects with at least one characteristic dimension below 100 nm renders possible phenomena that are not accessible at bigger length scales. This research field is termed nanofluidics and received its name only recently, but the roots in science and technology are broad. Nanofluidics has experienced a big growth during the last few years, confirmed by significant scientific and practical achievements. This review focuses on physical proper...
Modelling characteristics of photovoltaic panels with thermal phenomena taken into account
International Nuclear Information System (INIS)
Krac, Ewa; Górecki, Krzysztof
2016-01-01
In the paper a new form of the electrothermal model of photovoltaic panels is proposed. This model takes into account the optical, electrical and thermal properties of the considered panels, as well as electrical and thermal properties of the protecting circuit and thermal inertia of the considered panels. The form of this model is described and some results of measurements and calculations of mono-crystalline and poly-crystalline panels are presented
Are quantum-mechanical-like models possible, or necessary, outside quantum physics?
Plotnitsky, Arkady
2014-12-01
This article examines some experimental conditions that invite and possibly require recourse to quantum-mechanical-like mathematical models (QMLMs), models based on the key mathematical features of quantum mechanics, in scientific fields outside physics, such as biology, cognitive psychology, or economics. In particular, I consider whether the following two correlative features of quantum phenomena that were decisive for establishing the mathematical formalism of quantum mechanics play similarly important roles in QMLMs elsewhere. The first is the individuality and discreteness of quantum phenomena, and the second is the irreducibly probabilistic nature of our predictions concerning them, coupled to the particular character of the probabilities involved, as different from the character of probabilities found in classical physics. I also argue that these features could be interpreted in terms of a particular form of epistemology that suspends and even precludes a causal and, in the first place, realist description of quantum objects and processes. This epistemology limits the descriptive capacity of quantum theory to the description, classical in nature, of the observed quantum phenomena manifested in measuring instruments. Quantum mechanics itself only provides descriptions, probabilistic in nature, concerning numerical data pertaining to such phenomena, without offering a physical description of quantum objects and processes. While QMLMs share their use of the quantum-mechanical or analogous mathematical formalism, they may differ by the roles, if any, the two features in question play in them and by different ways of interpreting the phenomena they considered and this formalism itself. This article will address those differences as well.
Are quantum-mechanical-like models possible, or necessary, outside quantum physics?
International Nuclear Information System (INIS)
Plotnitsky, Arkady
2014-01-01
This article examines some experimental conditions that invite and possibly require recourse to quantum-mechanical-like mathematical models (QMLMs), models based on the key mathematical features of quantum mechanics, in scientific fields outside physics, such as biology, cognitive psychology, or economics. In particular, I consider whether the following two correlative features of quantum phenomena that were decisive for establishing the mathematical formalism of quantum mechanics play similarly important roles in QMLMs elsewhere. The first is the individuality and discreteness of quantum phenomena, and the second is the irreducibly probabilistic nature of our predictions concerning them, coupled to the particular character of the probabilities involved, as different from the character of probabilities found in classical physics. I also argue that these features could be interpreted in terms of a particular form of epistemology that suspends and even precludes a causal and, in the first place, realist description of quantum objects and processes. This epistemology limits the descriptive capacity of quantum theory to the description, classical in nature, of the observed quantum phenomena manifested in measuring instruments. Quantum mechanics itself only provides descriptions, probabilistic in nature, concerning numerical data pertaining to such phenomena, without offering a physical description of quantum objects and processes. While QMLMs share their use of the quantum-mechanical or analogous mathematical formalism, they may differ by the roles, if any, the two features in question play in them and by different ways of interpreting the phenomena they considered and this formalism itself. This article will address those differences as well. (paper)
Miano, Alberto Claudio; Ibarz, Albert; Augusto, Pedro Esteves Duarte
2016-03-01
The aim of this work was to demonstrate how ultrasound mechanisms (direct and indirect effects) improve the mass transfer phenomena in food processing, and which part of the process they are more effective in. Two model cases were evaluated: the hydration of sorghum grain (with two water activities) and the influx of a pigment into melon cylinders. Different treatments enabled us to evaluate and discriminate both direct (inertial flow and "sponge effect") and indirect effects (micro channel formation), alternating pre-treatments and treatments using an ultrasonic bath (20 kHz of frequency and 28 W/L of volumetric power) and a traditional water-bath. It was demonstrated that both the effects of ultrasound technology are more effective in food with higher water activity, the micro channels only forming in moist food. Moreover, micro channel formation could also be observed using agar gel cylinders, verifying the random formation of these due to cavitation. The direct effects were shown to be important in mass transfer enhancement not only in moist food, but also in dry food, this being improved by the micro channels formed and the porosity of the food. In conclusion, the improvement in mass transfer due to direct and indirect effects was firstly discriminated and described. It was proven that both phenomena are important for mass transfer in moist foods, while only the direct effects are important for dry foods. Based on these results, better processing using ultrasound technology can be obtained. Copyright © 2015 Elsevier B.V. All rights reserved.
Scrap melting model for steel converter founded on interfacial solid/liquid phenomena
Kruskopf, Ari; Holappa, Lauri
2017-12-01
The primary goal in steel converter operation is the removal of carbon from the hot metal. This is achieved by blowing oxygen into the melt. The oxidation of carbon produces a lot of heat. To avoid too high temperatures in the melt cold scrap (recycled steel) is charged into the converter. The melting rate is affected by heat and carbon mass transfer. A process model for steel converter is in development. This model is divided into several modules, which are fluid dynamics, heat- and mass-transfer, scrap melting and chemical reactions. This article focuses on the development of the scrap melting module. A numerical model for calculating temperature and carbon concentration in the melt is presented. The melt model is connected with the solid scrap model via solid/liquid interface. The interface model can take into account solidification of iron melt, melting of solidified layer, a situation without such phase changes, and scrap melting. The aim is to predict the melting rate of the scrap including the properties of the hot metal. The model is tested by calculating the melting rates for different scrap thicknesses. All of the stages in the interface model were taking place in the test calculations.
Ji, H.; Bhattacharjee, A.; Goodman, A.; Prager, S.; Daughton, W.; Cutler, R.; Fox, W.; Hoffmann, F.; Kalish, M.; Kozub, T.; Jara-Almonte, J.; Myers, C.; Ren, Y.; Sloboda, P.; Yamada, M.; Yoo, J.; Bale, S. D.; Carter, T.; Dorfman, S.; Drake, J.; Egedal, J.; Sarff, J.; Wallace, J.
2017-10-01
The FLARE device (Facility for Laboratory Reconnection Experiments; flare.pppl.gov) is a new laboratory experiment under construction at Princeton with first plasmas expected in the fall of 2017, based on the design of Magnetic Reconnection Experiment (MRX; mrx.pppl.gov) with much extended parameter ranges. Its main objective is to provide an experimental platform for the studies of magnetic reconnection and related phenomena in the multiple X-line regimes directly relevant to space, solar, astrophysical and fusion plasmas. The main diagnostics is an extensive set of magnetic probe arrays, simultaneously covering multiple scales from local electron scales ( 2 mm), to intermediate ion scales ( 10 cm), and global MHD scales ( 1 m). Specific example space physics topics which can be studied on FLARE will be discussed.
Angot, Philippe; Goyeau, Benoît; Ochoa-Tapia, J. Alberto
2017-06-01
We develop asymptotic modeling for two- or three-dimensional viscous fluid flow and convective transfer at the interface between a fluid and a porous layer. The asymptotic model is based on the fact that the thickness d of the interfacial transition region Ωfp of the one-domain representation is very small compared to the macroscopic length scale L . The analysis leads to an equivalent two-domain representation where transport phenomena in the transition layer of the one-domain approach are represented by algebraic jump boundary conditions at a fictive dividing interface Σ between the homogeneous fluid and porous regions. These jump conditions are thus stated up to first-order in O (d /L ) with d /L ≪1 . The originality and relevance of this asymptotic model lies in its general and multidimensional character. Indeed, it is shown that all the jump interface conditions derived for the commonly used 1D-shear flow are recovered by taking the tangential component of the asymptotic model. In that case, the comparison between the present model and the different models available in the literature gives explicit expressions of the effective jump coefficients and their associated scaling. In addition for multi-dimensional flows, the general asymptotic model yields the different components of the jump conditions including a new specific equation for the cross-flow pressure jump on Σ .
Directory of Open Access Journals (Sweden)
Dipankar Chatterjee
2017-06-01
Full Text Available A comparative assessment is done on the effectiveness of some developed and reported macroscopic and mesoscopic models deployed for addressing the three-dimensional thermo-fluidic transport during high-power laser surface alloying process. The macroscopic models include the most celebrated k–ε turbulence model and the large eddy simulation (LES model, whereas a kinetic theory-based lattice Boltzmann (LB approach is invoked under the mesoscopic paradigm. The time-dependent Navier–Stokes equations are transformed into the k–ε turbulence model by performing the Reynolds averaging technique, whereas a spatial filtering operation is used to produce the LES model. The models are suitably modified to address the turbulent melt-pool convection by using a modified eddy viscosity expression including a damping factor in the form of square root of the liquid fraction. The LB scheme utilizes three separate distribution functions to monitor the underlying hydrodynamic, thermal and compositional fields. Accordingly, the kinematic viscosity, thermal and mass diffusivities are adjusted independently. A single domain fixed-grid enthalpy-porosity approach is utilized to model the phase change phenomena in conjunction with an appropriate enthalpy updating closure scheme. The performance of these models is recorded by capturing the characteristic nature of the thermo-fluidic transport during the laser material processing. The maximum values of the pertinent parameters in the computational domain obtained from several modeling efforts are compared to assess their capabilities. The comparison shows that the prediction from the k–ε turbulence model is higher than the LES and LB models. In addition, the results from all three models are compared with the available experimental results in the form of dimensionless composition of the alloyed layer along the dimensionless depth of the pool. The comparison reveals that the LB and the LES approaches are better
Energy Technology Data Exchange (ETDEWEB)
Bourg, I.C.; Sposito, G.
2011-05-01
Ion exchange phenomena involve the population of readily exchangeable ions, the subset of adsorbed solutes that balance the intrinsic surface charge and can be readily replaced by major background electrolyte ions (Sposito, 2008). These phenomena have occupied a central place in soil chemistry research since Way (1850) first showed that potassium uptake by soils resulted in the release of an equal quantity of moles of charge of calcium and magnesium. Ion exchange phenomena are now routinely modeled in studies of soil formation (White et al., 2005), soil reclamation (Kopittke et al., 2006), soil fertilitization (Agbenin and Yakubu, 2006), colloidal dispersion/flocculation (Charlet and Tournassat, 2005), the mechanics of argillaceous media (Gajo and Loret, 2007), aquitard pore water chemistry (Tournassat et al., 2008), and groundwater (Timms and Hendry, 2007; McNab et al., 2009) and contaminant hydrology (Chatterjee et al., 2008; van Oploo et al., 2008; Serrano et al., 2009).
Blanco, Celia; Ribó, Josep M; Hochberg, David
2015-02-01
We derive the class of population balance equations (PBE), recently applied to model the Viedma deracemization experiment, from an underlying microreversible kinetic reaction scheme. The continuum limit establishing the relationship between the micro- and macroscopic processes and the associated particle fluxes erases the microreversible nature of the molecular interactions in the population growth rate functions and limits the scope of such PBE models to strict kinetic control. The irreversible binary agglomeration processes modeled in those PBEs contribute an additional source of kinetic control. These limitations are crucial regarding the question of the origin of biological homochirality, where the interest in any model lies precisely in its ability for absolute asymmetric synthesis and the amplification of the tiny inherent statistical chiral fluctuations about the ideal racemic composition up to observable enantiometric excess levels.
Directory of Open Access Journals (Sweden)
Tomasz MATYJA
2014-06-01
Full Text Available This paper presents the concept and an example of usage of Simulink blocks library with which dynamic simulation of complex systems with rotating shafts, rigid rotors, bearings and couplings, general rotating power transmission systems of any configuration can be performed. The assumption is that library is modular and expandable. The main part of the library currently being developed is rigid rotor model with 6 degrees of freedom of the static and dynamic imbalance. Other components are: block modeling the bearing with mounting stiffness, damping and inertia; linear elastic-damping element and rigid beam finite element (RFEM. Also in preparation are: block modeling shaft with Timoshenko beam elements and Rayleigh damping, block modeling clutch.
Energy Technology Data Exchange (ETDEWEB)
Zabaniotou, A.; Damartzis, Th. [Department of Chemical Engineering, Aristotle University of Thessaloniki, University Box 455, 24154 Thessaloniki (Greece)
2007-08-15
In the present study, the development of a mathematical model for the description of the pyrolysis of a single solid olive kernel particle and the prediction of the fast pyrolysis product yields, is presented. Kinetic model is coupled with heat transfer model. The global degradation of biomass is based on Koufopanos et al. mechanism and described by two parallel 1-order reactions. The analysis is focused on primary degradation for small particle and simulations have been carried out for a spherical particle, with radius of 175 {mu}m. The model has been validated against experiments carried out in a laboratory wire mesh reactor, for temperature range from 573 K to 873 K and a heating rate of 200 K/s. The results of the simulation are in good agreement with the experimental data, regarding temperature, conversion histories and product distribution of olive kernel fast pyrolysis. The numerical method applied was finite difference for the heat transfer model and Runge-Kutta 4th order method for chemical kinetics model equations. (author)
Evaluating a Model of Youth Physical Activity
Heitzler, Carrie D.; Lytle, Leslie A.; Erickson, Darin J.; Barr-Anderson, Daheia; Sirard, John R.; Story, Mary
2010-01-01
Objective: To explore the relationship between social influences, self-efficacy, enjoyment, and barriers and physical activity. Methods: Structural equation modeling examined relationships between parent and peer support, parent physical activity, individual perceptions, and objectively measured physical activity using accelerometers among a…
Various Transport Phenomena and Modeling in a Methane Reformer Duct for PEMFCs
International Nuclear Information System (INIS)
Jinliang Yuan; Fuan Ren; Jinliang Yuan; Bengt Sunden
2006-01-01
There are various physical processes (such as mass, heat and momentum transport) integrated with catalytic chemical reactions in a methane steam reforming duct. It is often found that endothermic and exothermic reactions in the ducts are strongly coupled by heat transfer from adjacent catalytic combustion ducts. In this paper, a three-dimensional calculation method is developed to simulate and analyze steam reforming of methane, and the effects on various transport processes in a steam reforming duct. The reformer conditions such as mass balances associated with the reforming reactions and gas permeation to/from the porous catalyst layer are applied in the analysis. The predicted results are presented and discussed for a composite duct consisting of a porous catalyst reaction area, the gas flow duct and solid layers. Parametric studies are conducted and the results show that the variables, such as fuel reformer temperatures and catalyst loadings, have significant effects on the transport processes and reformer performance. (authors)
International Nuclear Information System (INIS)
Fernandez, J.M.; Piault, E.; Macouillard, D.; Juncos, C.
2006-01-01
In 1960 experiments were carried out on the transfer of 9 Sr between soil, grapes and wine. The experiments were conducted in situ on a piece of land limited by two control strips. The 9 Sr migration over the last 40 years was studied by performing radiological and physico-chemical characterizations of the soil on eight 70 cm deep cores. The vertical migration modeling of 9 Sr required the definition of a triple layer conceptual model integrating the rainwater infiltration at constant flux as the only external factor of influence. Afterwards the importance of a detailed soil characterization for modeling was discussed and satisfactory simulation of the 9 Sr vertical transport was obtained and showed a calculated migration rate of about 1.0 cm year -1 in full agreement with the in situ measured values. The discussion was regarding some of the key parameters such as granulometry, organic matter content (in the Van Genuchten parameter determination), Kd and the efficient rainwater infiltration. Besides the experimental data, simplifying assumptions in modeling such as water-soil redistribution calculation and factual discontinuities in conceptual model were examined
Modeling the phenomena of dehydration and flooding of a polymer electrolyte membrane fuel cell
Gerteisen, Dietmar; Heilmann, Timothy; Ziegler, Christoph
A one-dimensional, two-phase, transient PEM fuel cell model including gas diffusion layer, cathode catalyst layer and membrane is developed. The electrode is assumed to consist of a network of dispersed Pt/C forming spherically shaped agglomerated zones that are filled with electrolyte. Water is modeled in all three phases: vapor, liquid and dissolved in the ionomer to capture the effect of dehydration of the ionomer as well as flooding of the porous media. The anode is modeled as a sophisticated spatially reduced interface. Motivated by environmental scanning electron microscope (ESEM) images of contact angles for microscopic water droplets on fibers of the gas diffusion layer, we introduce the feature of immobile saturation. A step change of the saturation between the catalyst layer and the gas diffusion layer is modeled based on the assumption of a continuous capillary pressure at the interface. The model is validated against voltammetry experiments under various humidification conditions which all show hysteresis effects in the mass transport limited region. The transient saturation profiles clearly show that insufficient liquid water removal causes pore flooding, which is responsible for the oxygen mass transport limitation at high current density values. The simulated and measured current responses from chronoamperometry experiments are compared and analyzed.
Gray, William G; Miller, Cass T
2009-05-01
This work is the fifth in a series of papers on the thermodynamically constrained averaging theory (TCAT) approach for modeling flow and transport phenomena in multiscale porous medium systems. The general TCAT framework and the mathematical foundation presented in previous works are used to develop models that describe species transport and single-fluid-phase flow through a porous medium system in varying physical regimes. Classical irreversible thermodynamics formulations for species in fluids, solids, and interfaces are developed. Two different approaches are presented, one that makes use of a momentum equation for each entity along with constitutive relations for species diffusion and dispersion, and a second approach that makes use of a momentum equation for each species in an entity. The alternative models are developed by relying upon different approaches to constrain an entropy inequality using mass, momentum, and energy conservation equations. The resultant constrained entropy inequality is simplified and used to guide the development of closed models. Specific instances of dilute and non-dilute systems are examined and compared to alternative formulation approaches.
Modelling of phenomena in solid state for the steel casting cooled by liquid
Directory of Open Access Journals (Sweden)
A. Kulawik
2011-04-01
Full Text Available In this paper a mathematical model of cooling process for steel castings is presented. Effect of convective motion of the coolant onmaterial structure after cooling process is investigated. Mathematical and numerical model based on Generalized Difference Method for axysimmertric elements is used. To solve the Navier-Stokes equation the characteristic based split scheme (CBS has been applied. The solution of the heat transport equation with the convective term has been obtained by a stabilized meshless method. To determine of the phase transformation the macroscopic model built on the basis of Time Temperature Transformation diagrams for continuous cooling of medium-carbon steel has been used. The temporary temperature fields, the phase transformation, thermal and structural strains for the cooled element and the fields of temperature and velocity for the coolant have been determined.
Agent-Based Model Approach to Complex Phenomena in Real Economy
Iyetomi, H.; Aoyama, H.; Fujiwara, Y.; Ikeda, Y.; Souma, W.
An agent-based model for firms' dynamics is developed. The model consists of firm agents with identical characteristic parameters and a bank agent. Dynamics of those agents are described by their balance sheets. Each firm tries to maximize its expected profit with possible risks in market. Infinite growth of a firm directed by the ``profit maximization" principle is suppressed by a concept of ``going concern". Possibility of bankruptcy of firms is also introduced by incorporating a retardation effect of information on firms' decision. The firms, mutually interacting through the monopolistic bank, become heterogeneous in the course of temporal evolution. Statistical properties of firms' dynamics obtained by simulations based on the model are discussed in light of observations in the real economy.
A Reduced-Order Model of Transport Phenomena for Power Plant Simulation
Energy Technology Data Exchange (ETDEWEB)
Paul Cizmas; Brian Richardson; Thomas Brenner; Raymond Fontenot
2009-09-30
A reduced-order model based on proper orthogonal decomposition (POD) has been developed to simulate transient two- and three-dimensional isothermal and non-isothermal flows in a fluidized bed. Reduced-order models of void fraction, gas and solids temperatures, granular energy, and z-direction gas and solids velocity have been added to the previous version of the code. These algorithms are presented and their implementation is discussed. Verification studies are presented for each algorithm. A number of methods to accelerate the computations performed by the reduced-order model are presented. The errors associated with each acceleration method are computed and discussed. Using a combination of acceleration methods, a two-dimensional isothermal simulation using the reduced-order model is shown to be 114 times faster than using the full-order model. In the pursue of achieving the objectives of the project and completing the tasks planned for this program, several unplanned and unforeseen results, methods and studies have been generated. These additional accomplishments are also presented and they include: (1) a study of the effect of snapshot sampling time on the computation of the POD basis functions, (2) an investigation of different strategies for generating the autocorrelation matrix used to find the POD basis functions, (3) the development and implementation of a bubble detection and tracking algorithm based on mathematical morphology, (4) a method for augmenting the proper orthogonal decomposition to better capture flows with discontinuities, such as bubbles, and (5) a mixed reduced-order/full-order model, called point-mode proper orthogonal decomposition, designed to avoid unphysical due to approximation errors. The limitations of the proper orthogonal decomposition method in simulating transient flows with moving discontinuities, such as bubbling flows, are discussed and several methods are proposed to adapt the method for future use.
Ordering phenomena and non-equilibrium properties of lattice gas models
International Nuclear Information System (INIS)
Fiig, T.
1994-03-01
This report falls within the general field of ordering processes and non-equilibrium properties of lattice gas models. The theory of diffuse scattering of lattice gas models originating from a random distribution of clusters is considered. We obtain relations between the diffuse part of the structure factor S dif (q), the correlation function C(r), and the size distribution of clusters D(n). For a number of distributions we calculate S dif (q) exactly in one dimension, and discuss the possibility for a Lorentzian and a Lorentzian square lineshape to arise. We discuss the two- and three-dimensional oxygen ordering processes in the high T c superconductor YBa 2 Cu 3 O 6+x based on a simple anisotropic lattice gas model. We calculate the structural phase diagram by Monte Carlo simulation and compared the results with experimental data. The structure factor of the oxygen ordering properties has been calculated in both two and three dimensions by Monte Carlo simulation. We report on results obtained from large scale computations on the Connection Machine, which are in excellent agreement with recent neutron diffraction data. In addition we consider the effect of the diffusive motion of metal-ion dopants on the oxygen ordering properties on YBa 2 Cu 3 O 6+x . The stationary properties of metastability in long-range interaction models are studied by application of a constrained transfer matrix (CTM) formalism. The model considered, which exhibits several metastable states, is an extension of the Blume Capel model to include weak long-range interactions. We show, that the decay rate of the metastable states is closely related to the imaginary part of the equilibrium free-energy density obtained from the CTM formalism. We discuss a class of lattice gas model for dissipative transport in the framework of a Langevin description, which is capable of producing power law spectra for the density fluctuations. We compare with numerical results obtained from simulations of a
Energy Technology Data Exchange (ETDEWEB)
Chijimatsu, M.; Borgesson, L.; Fujita, T.; Jussila, P.; Nguyen, S.; Rutqvist, J.; Jing, L.; Hernelind, J.
2009-02-01
In Task A of the international DECOVALEX-THMC project, five research teams study the influence of thermal-hydro-mechanical (THM) coupling on the safety of a hypothetical geological repository for spent fuel. In order to improve the analyses, the teams calibrated their bentonite models with results from laboratory experiments, including swelling pressure tests, water uptake tests, thermally gradient tests, and the CEA mock-up THM experiment. This paper describes the mathematical models used by the teams, and compares the results of their calibrations with the experimental data.
Oberrecht, Stephen Patrick
Because of cultural and linguistic influences on science learning involving students from diverse cultural and linguistic backgrounds, calls have been made for teachers to enact teaching that is sensitive to these students' backgrounds. However, most of the research involving such students has tended to focus on students at elementary grade levels from predominantly two linguistic backgrounds, Hispanic and Haitian Creole, learning science concepts mainly in the life sciences. Also, most of the studies examined classroom interactions between teachers and the students and among students. Not much attention had been paid to how students talk about ideas inherent in scientific phenomena in an outside-the-classroom context and much less on how that talk relates to that of the classroom. Thus, this research extends knowledge in the area of science learning involving students learning science in a language other than their first language to include students from a language background other than Hispanic and Haitian Creole at not only the high school level but also their learning of ideas in a content area other than the life science (i.e., the physical sciences). More importantly, this research extends knowledge in the area by relating science learning outside and inside the classroom. This dissertation describes this exploratory research project that adopted a case study strategy. The research involved seven Form Two (tenth grade) students (three boys and four girls) from one public, mixed gender day secondary school in rural Kenya. I collected data from the students through focus group discussions as they engaged in talking about ideas inherent in selected physical science phenomena and activities they encountered in their everyday lives, as well as learned about in their science classrooms. I supplemented these data with data from one-on-one semi-structured interviews with two teachers (one for chemistry and one for physics) on their teaching of ideas investigated in
Transport phenomena in environmental engineering
Sander, Aleksandra; Kardum, Jasna Prlić; Matijašić, Gordana; Žižek, Krunoslav
2018-01-01
A term transport phenomena arises as a second paradigm at the end of 1950s with high awareness that there was a strong need to improve the scoping of chemical engineering science. At that point, engineers became highly aware that it is extremely important to take step forward from pure empirical description and the concept of unit operations only to understand the specific process using phenomenological equations that rely on three elementary physical processes: momentum, energy and mass transport. This conceptual evolution of chemical engineering was first presented with a well-known book of R. Byron Bird, Warren E. Stewart and Edwin N. Lightfoot, Transport Phenomena, published in 1960 [1]. What transport phenomena are included in environmental engineering? It is hard to divide those phenomena through different engineering disciplines. The core is the same but the focus changes. Intention of the authors here is to present the transport phenomena that are omnipresent in treatment of various process streams. The focus in this chapter is made on the transport phenomena that permanently occur in mechanical macroprocesses of sedimentation and filtration for separation in solid-liquid particulate systems and on the phenomena of the flow through a fixed and a fluidized bed of particles that are immanent in separation processes in packed columns and in environmental catalysis. The fundamental phenomena for each thermal and equilibrium separation process technology are presented as well. Understanding and mathematical description of underlying transport phenomena result in scoping the separation processes in a way that ChEs should act worldwide.
2011-02-25
wavelet analyses, evolutionary algorithms, Ritz or stochastic methods, and others. These techniques are designed for linear vibrations while far...and selecting DOF of FE models have been extensively studied by var - ious methods and distinct perspectives, such as the reduction of the interface DOF
Multiphysical Modeling of Transport Phenomena During Laser Welding of Dissimilar Steels
Métais, A.; Matteï, S.; Tomashchuk, I.; Gaied, S.
The success of new high-strength steels allows attaining equivalent performances with lower thicknesses and significant weight reduction. The welding of new couples of steel grades requires development and control of joining processes. Thanks to high precision and good flexibility, laser welding became one of the most used processes for joining of dissimilar welded blanks. The prediction of the local chemical composition in the weld formed between dissimilar steels in function of the welding parameters is essential because the dilution rate and the distribution of alloying elements in the melted zone determines the final tensile strength of the weld. The goal of the present study is to create and to validate a multiphysical numerical model studying the mixing of dissimilar steels in laser weld pool. A 3D modelling of heat transfer, turbulent flow and transport of species provides a better understanding of diffusion and convective mixing in laser weld pool. The present model allows predicting the weld geometry and element distribution. The model has been developed based on steady keyhole approximation and solved in quasi-stationary form in order to reduce the computation time. Turbulent flow formulation was applied to calculate velocity field. Fick law for diluted species was used to simulate the transport of alloying elements in the weld pool. To validate the model, a number of experiments have been performed: tests using pure 100 μm thick Ni foils like tracer and weld between a rich and poor manganese steels. SEM-EDX analysis of chemical composition has been carried out to obtain quantitative mapping of Ni and Mn distributions in the melted zone. The results of simulations have been found in good agreement with experimental data.
Chris Hill
2012-01-01
The months that have passed since the last CMS Bulletin have been a very busy and exciting time for CMS physics. We have gone from observing the very first 8TeV collisions produced by the LHC to collecting a dataset of the collisions that already exceeds that recorded in all of 2011. All in just a few months! Meanwhile, the analysis of the 2011 dataset and publication of the subsequent results has continued. These results come from all the PAGs in CMS, including searches for the Higgs boson and other new phenomena, that have set the most stringent limits on an ever increasing number of models of physics beyond the Standard Model including dark matter, Supersymmetry, and TeV-scale gravity scenarios, top-quark physics where CMS has overtaken the Tevatron in the precision of some measurements, and bottom-quark physics where CMS made its first discovery of a new particle, the Ξ*0b baryon (candidate event pictured below). Image 2: A Ξ*0b candidate event At the same time POGs and PAGs...
A state of the art on the flooding phenomena and countercurrent flow limiting modeling
Energy Technology Data Exchange (ETDEWEB)
Jeong, Young Jong; Chang, Won Pyo [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)
1996-07-01
Countercurrent flow limiting phenomenon and its modeling for vertical and nearly horizontal pipes has been reviewed in two phase flow. A number of analytical and empirical model have been developed for flooding in the vertical pipes and annulars. These may be classified as stability theory, envelope theory, static equilibrium theory, slug formation theory, Wallis correlation, and Kutateladze correlation. The theories and empirical correlations are reviewed and comparison with the various experimental data. The scatter of the experimental data is large because of the different flooding condition and because of the influence of the experimental conditions. Application of flooding for PWR best estimate system codes is reviewed. The codes provide the user options to implement CCFL correlation for the specific geometry. The codes can accommodate generally Wallis, Kutateladze, or Bankoff correlation. 4 tabs., 36 figs., 52 refs. (Author).
Design issues of time-based phenomena and the notion of a persistent model
DEFF Research Database (Denmark)
Peters, Brady
2012-01-01
This chapter reflects on how sound can become part the architectural design process. Sound is a complex phenomenon that traditional architectural drawing tools do not capture well. Parametric tools allow for the encoding of relationships between material, geometry, and acoustic performance...... in a digital model. Computational simulation tools can give visual and aural feedback on how designs perform. These tools give architects the ability to contemplate the sound of architectural propositions. Different sounds, sound positions, and listener positions can be tested, as can different geometric...... and material configurations. Using these tools architects can design for sound. Sound should be a part of the architectural design process and in order for it to be a useful design parameter; it must be able to be considered in the digital modeling environment. We form a spatial impression of our surroundings...
Modeling studies of transport bifurcation phenomena in a collisional drift wave turbulence
Hajjar, Rima; Diamond, Patrick; Tynan, Georges; Ashourvan, Arash
2016-10-01
Self-organization of drift wave turbulence via particle transport and Reynolds stresses is a mechanism for turbulence suppression and reduction of cross field transport. This energy transfer mechanism between microscale drift waves and mesoscale zonal flows can create a transport bifurcation and trigger the formation of an internal transport barrier. We report here on studies investigating transport bifurcation dynamics in the CSDX linear device using a 1D reduced turbulence and mean field evolution model. This two-mixing scale Hasegawa-Wakatani based model evolves spatio-temporal variations of three plasma fields: the mean density n, the mean vorticity u and the turbulent potential enstrophy e. The model adopts inhomogeneous potential vorticity mixing on a mixing length the expression of which is related to the Rhines' scale and to the mode scale (i.e. is ∇n and ∇u dependent). The model is based on expressions for turbulent fluxes of n, u and e derived from mixing length concepts. Turbulent particle and enstrophy transport are written as diffusive, but a residual stress part is included in the expression for the vorticity flux. Mixed boundary conditions are used at both ends of the domain and an external boundary fueling source is added. Simulation results show a steepening in the particle density profiles with B along with the formation of a net flow shear layer resulting from the vorticity mixing. These results suggest that the system dynamic is capable of sustaining the plasma core by means of a purely diffusive particle flux, without any explicit inward particle pinch.
Investigation of Multicritical Phenomena in ANNNI Model by Monte Carlo Methods
Directory of Open Access Journals (Sweden)
A. K. Murtazaev
2012-01-01
Full Text Available The anisotropic Ising model with competing interactions is investigated in wide temperature range and |J1/J| parameters by means of Monte Carlo methods. Static critical exponents of the magnetization, susceptibility, heat capacity, and correlation radius are calculated in the neighborhood of Lifshitz point. According to obtained results, a phase diagram is plotted, the coordinates of Lifshitz point are defined, and a character of multicritical behavior of the system is detected.
A validated physical model of greenhouse climate.
Bot, G.P.A.
1989-01-01
In the greenhouse model the momentaneous environmental crop growth factors are calculated as output, together with the physical behaviour of the crop. The boundary conditions for this model are the outside weather conditions; other inputs are the physical characteristics of the crop, of the
Shirkole, S S; Sutar, P P
2018-02-01
In the present study, the GAB and moisture migration rate models were used to predict the shelf life of paprika under domestic (40 °C and 90% RH) and industrial (5, 10, 15 and 20 °C with 70% RH) storage conditions. The correlations between physicochemical characteristics and moisture content of paprika were developed to estimate the stability of the paprika. The estimated shelf life of low moisture paprika (4.40% dry basis) was found to be 101 and 31 days in HDPE and LDPE packages, respectively when stored in domestic condition. In industrial storage condition, the shelf life prediction was 5.47 years in HDPE and 1.68 years in LDPE packages. The first order kinetic models of extractable color (ASTA) and degree of caking described the quality degradation of paprika during storage. The relative humidity and temperature of the storage environment were significant parameters affecting the stability of paprika. The shelf life of paprika can be extended by storage at or below monolayer moisture content and low temperature.
Experimental Measurement of Flow Phenomena in a VHTR Lower Plenum Model
Energy Technology Data Exchange (ETDEWEB)
Hugh M. McIlroy Jr.; Keith G. Condie; Glenn E. McCreery; Donald M. McEligot; Robert J. Pink
2006-06-01
The Very-High-Temperature Reactor (VHTR) is one of six reactor technologies chosen for further development by the Generation IV International Forum. In addition this system is the leading candidate for the Next Generation Nuclear Power (NGNP) Project in the U.S which has the goal of demonstrating the production of emissions free electricity and hydrogen by 2015. In preparation for the thermal-hydraulics and safety analyses that will be required to confirm the performance of the NGNP, work has begun on readying the computational tools that will be needed to predict the thermal-hydraulics conditions and safety margins of the reactor design. Meaningful feasibility studies for VHTR designs will require accurate, reliable predictions of material temperatures which depend upon the thermal convection in the coolant channels of the core and other components. Unfortunately, one-dimensional system codes for gas-cooled reactors typically underpredict these temperatures, particularly for reduced power operations and hypothesized accident scenarios. Likewise, most turbulence models in general-purpose CFD codes also underpredict these temperatures. Matched-Index-of-Refraction (MIR) fluid dynamics experiments have been designed and built to develop benchmark databases for the assessment of CFD solutions of the momentum equations, scalar mixing and turbulence models for typical VHTR plenum geometries in the limiting case of negligible buoyancy and constant fluid properties.
International Nuclear Information System (INIS)
Allen, M.D.; Pilch, M.M.; Blanchat, T.K.; Griffith, R.O.; Nichols, R.T.
1994-05-01
The Surtsey Facility at Sandia National Laboratories (SNL) is used to perform scaled experiments that simulate hypothetical high-pressure melt ejection (HPME) accidents in a nuclear power plant (NPP). These experiments are designed to investigate the effect of specific phenomena associated with direct containment heating (DCH) on the containment load, such as the effect of physical scale, prototypic subcompartment structures, water in the cavity, and hydrogen generation and combustion. In the Integral Effects Test (IET) series, 1:10 linear scale models of the Zion NPP structures were constructed in the Surtsey vessel. The RPV was modeled with a steel pressure vessel that had a hemispherical bottom head, which had a 4-cm hole in the bottom head that simulated the final ablated hole that would be formed by ejection of an instrument guide tube in a severe NPP accident. Iron/alumina/chromium thermite was used to simulate molten corium that would accumulate on the bottom head of an actual RPV. The chemically reactive melt simulant was ejected by high-pressure steam from the RPV model into the scaled reactor cavity. Debris was then entrained through the instrument tunnel into the subcompartment structures and the upper dome of the simulated reactor containment building. The results of the IET experiments are given in this report
Energy Technology Data Exchange (ETDEWEB)
Allen, M.D.; Pilch, M.M.; Blanchat, T.K.; Griffith, R.O. [Sandia National Labs., Albuquerque, NM (United States); Nichols, R.T. [Ktech Corp., Albuquerque, NM (United States)
1994-05-01
The Surtsey Facility at Sandia National Laboratories (SNL) is used to perform scaled experiments that simulate hypothetical high-pressure melt ejection (HPME) accidents in a nuclear power plant (NPP). These experiments are designed to investigate the effect of specific phenomena associated with direct containment heating (DCH) on the containment load, such as the effect of physical scale, prototypic subcompartment structures, water in the cavity, and hydrogen generation and combustion. In the Integral Effects Test (IET) series, 1:10 linear scale models of the Zion NPP structures were constructed in the Surtsey vessel. The RPV was modeled with a steel pressure vessel that had a hemispherical bottom head, which had a 4-cm hole in the bottom head that simulated the final ablated hole that would be formed by ejection of an instrument guide tube in a severe NPP accident. Iron/alumina/chromium thermite was used to simulate molten corium that would accumulate on the bottom head of an actual RPV. The chemically reactive melt simulant was ejected by high-pressure steam from the RPV model into the scaled reactor cavity. Debris was then entrained through the instrument tunnel into the subcompartment structures and the upper dome of the simulated reactor containment building. The results of the IET experiments are given in this report.
Numerical modelling in material physics
International Nuclear Information System (INIS)
Proville, L.
2004-12-01
The author first briefly presents his past research activities: investigation of a dislocation sliding in solid solution by molecular dynamics, modelling of metal film growth by phase field and Monte Carlo kinetics, phase field model for surface self-organisation, phase field model for the Al 3 Zr alloy, calculation of anharmonic photons, mobility of bipolarons in superconductors. Then, he more precisely reports the mesoscopic modelling in phase field, and some atomistic modelling (dislocation sliding, Monte Carlo simulation of metal surface growth, anharmonic network optical spectrum modelling)
Investigation of high-p{sub T} phenomena within a partonic transport model
Energy Technology Data Exchange (ETDEWEB)
Fochler, Oliver
2011-10-26
In the work presented herein the microscopic transport model BAMPS (Boltzmann Approach to Multi-Parton Scatterings) is applied to simulate the time evolution of the hot partonic medium that is created in Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC) and in Pb+Pb collisions at the recently started Large Hadron Collider (LHC). The study is especially focused on the investigation of the nuclear modification factor R{sub AA}, that quantifies the suppression of particle yields at large transverse momentum with respect to a scaled proton+proton reference, and the simultaneous description of the collective properties of the medium in terms of the elliptic flow v{sub 2} within a common framework. (orig.)
Directory of Open Access Journals (Sweden)
Carrick Detweiler
2014-05-01
Full Text Available Understanding the dynamics of bodies of water and their impact on the global environment requires sensing information over the full volume of water. In this article, we develop a gradient-based decentralized controller that dynamically adjusts the depth of a network of underwater sensors to optimize sensing for computing maximally detailed volumetric models. We prove that the controller converges to a local minimum and show how the controller can be extended to work with hybrid robot and sensor network systems. We implement the controller on an underwater sensor network with depth adjustment capabilities. Through simulations and in-situ experiments, we verify the functionality and performance of the system and algorithm.
Naidu, Gayathri
2016-08-27
The application of vacuum to direct contact membrane distillation (vacuum enhanced direct contact membrane distillation, V-DCMD) removed condensable gasses and reduced partial pressure in the membrane pores, achieving 37.6% higher flux than DCMD at the same feed temperature. Transfer mechanism and temperature distribution profile in V-DCMD were studied. The empirical flux decline (EFD) model represented fouling profiles of V-DCMD. In a continuous V-DCMD operation with moderate temperature (55 degrees C) and permeate pressure (300 mbar) for treating wastewater ROC, a flux of 16.0 +/- 0.3 L/m(2) h and high quality distillate were achieved with water flushing, showing the suitability of V-DCMD for ROC treatment. (C) 2016 Elsevier B.V. All rights reserved.
Friction phenomena in a two-dimensional Frenkel–Kontorova model
International Nuclear Information System (INIS)
Mai-Mai, Lin; Wen-Shan, Duan; Jian-Min, Chen
2010-01-01
By using the molecular dynamic simulation method with a fourth-order Runge–Kutta algorithm, a two-dimensional dc- and ac-driven Frenkel–Kontorova (FK) model with a square symmetry substrate potential for a square lattice layer has been investigated in this paper. For this system, the effects of many different parameters on the average velocity and the static friction force have been studied. It is found that not only the amplitude and frequency of ac-driven force, but also the direction of the external driving force and the misfit angle between two layers have some strong influences on the static friction force. It can be concluded that the superlubricity phenomenon appears easily with a larger ac amplitude and lower ac frequency for some special direction of the external force and misfit angle. (condensed matter: structure, thermal and mechanical properties)
International Nuclear Information System (INIS)
Kikuchi, Shin; Ohshima, Hiroyuki; Hashimoto, Kenro
2011-01-01
Computational study of the sodium-water reaction at the gas (water) - liquid (sodium) interface has been carried out using ab initio (first-principle) method. A possible reaction channel has been identified for the stepwise OH bond dissociations of a single water molecule. The energetics including the binding energy of a water molecule to the sodium surface, the activation energies of the bond cleavages, and the reaction energies, have been evaluated, and the rate constants of the first and second OH bond-breakings have been compared. The results are used as the basis for constructing the chemical reaction model used in a multi-dimensional sodium-water reaction code, SERAPHIM, being developed by JAEA toward the safety assessment of the steam generator (SG) in a sodium-cooled fast reactor (SFR). (author)
How to Become a Dictator: a Simple Model from Physics
Galam, Serge
The dynamics of majority rule voting in hierarchical structures is studied using concepts from collective phenomena in physics. In the case of a two-party competition a very simple model to a democratic dictatorship is presented. For each running group, a critical threshold (in the overall support) is found to ensure full and total power at the hierarchy top. However, the respective value of this threshold may vary a lot from one party to the other. It is this difference which creates the dictatorian nature of the democratic voting system. While climbing up the hierarchy, the initial majority-minority ratio can be reversed at the profit of actual running party. Such a reversal is shown to be driven by the natural inertia of being in power. The model could shed light on last century Eastern European Communist collapse.
Modelling psychiatric and cultural possession phenomena with suggestion and fMRI.
Deeley, Quinton; Oakley, David A; Walsh, Eamonn; Bell, Vaughan; Mehta, Mitul A; Halligan, Peter W
2014-04-01
Involuntary movements occur in a variety of neuropsychiatric disorders and culturally influenced dissociative states (e.g., delusions of alien control and attributions of spirit possession). However, the underlying brain processes are poorly understood. We combined suggestion and fMRI in 15 highly hypnotically susceptible volunteers to investigate changes in brain activity accompanying different experiences of loss of self-control of movement. Suggestions of external personal control and internal personal control over involuntary movements modelled delusions of control and spirit possession respectively. A suggestion of impersonal control by a malfunctioning machine modelled technical delusions of control, where involuntary movements are attributed to the influence of machines. We found that (i) brain activity and/or connectivity significantly varied with different experiences and attributions of loss of agency; (ii) compared to the impersonal control condition, both external and internal personal alien control were associated with increased connectivity between primary motor cortex (M1) and brain regions involved in attribution of mental states and representing the self in relation to others; (iii) compared to both personal alien control conditions, impersonal control of movement was associated with increased activity in brain regions involved in error detection and object imagery; (iv) there were no significant differences in brain activity, and minor differences in M1 connectivity, between the external and internal personal alien control conditions. Brain networks supporting error detection and object imagery, together with representation of self and others, are differentially recruited to support experiences of impersonal and personal control of involuntary movements. However, similar brain systems underpin attributions and experiences of external and internal alien control of movement. Loss of self-agency for movement can therefore accompany different kinds of
Inertial confinement fusion reactor cavity phenomena
International Nuclear Information System (INIS)
Bohachevsky, I.O.; Hafer, J.F.; Devaney, J.J.; Pendergrass, J.H.
1978-01-01
Cavity phenomena in Inertial Confinement Fusion (ICF) are created by the interaction of energy released by the fuel pellet microexplosion with the medium inside the reactor cavity. The ambient state of the medium in ICF reactor cavities is restricted primarily by its effects on laser beam propagation and on the fuel pellet trajectory. Therefore, a relatively wide choice of ambient conditions can be exploited to gain first-wall protection and advantages in energy extraction. Depending on the choice of ambient cavity conditions and on fuel pellet design, a variety of physical phenomena may develop and dominate the ICF reactor cavity design. Because of the cavity phenomena, the forms of energy released by the fuel-pellet microexplosion are modified before reaching the first wall, thus giving rise to different cavity design problems. The types of cavity phenomena encountered in the conceptual design of ICF reactors are examined, the approaches available for their modeling and analysis are discussed, and some results are presented. Most phenomena are sufficiently well understood to permit valid engineering assessments of the proposed ICF reactor concepts
Physical modelling of near-wall phenomena in entrained-flow coal gasifiers
Troiano, Maurizio
2015-01-01
Combustion and gasification under slagging conditions are key aspects of the design of modern entrained-flow reactors for thermal conversion of solid fuels, aimed at increasing the overall energy efficiency. In these systems, solid particles migrate toward the reactor walls, due to swirled/tangential flow induced in the reaction chamber and to turbophoresis, generating, thanks to the very high operating temperatures, a slag layer that flows along the reactor internal walls and is drained to t...
International Nuclear Information System (INIS)
Hategan, Cornel
2002-01-01
Theory of Threshold Phenomena in Quantum Scattering is developed in terms of Reduced Scattering Matrix. Relationships of different types of threshold anomalies both to nuclear reaction mechanisms and to nuclear reaction models are established. Magnitude of threshold effect is related to spectroscopic factor of zero-energy neutron state. The Theory of Threshold Phenomena, based on Reduced Scattering Matrix, does establish relationships between different types of threshold effects and nuclear reaction mechanisms: the cusp and non-resonant potential scattering, s-wave threshold anomaly and compound nucleus resonant scattering, p-wave anomaly and quasi-resonant scattering. A threshold anomaly related to resonant or quasi resonant scattering is enhanced provided the neutron threshold state has large spectroscopic amplitude. The Theory contains, as limit cases, Cusp Theories and also results of different nuclear reactions models as Charge Exchange, Weak Coupling, Bohr and Hauser-Feshbach models. (author)
Modeling of polarization phenomena due to RF sheaths and electron beams in magnetized plasma
International Nuclear Information System (INIS)
Faudot, E.
2005-01-01
This work investigates the problematic of hot spots induced by accelerated particle fluxes in tokamaks. It is shown that the polarization due to sheaths in the edge plasma in which an electron beam at a high level of energy is injected, can reach several hundreds volts and thus extend the deposition area. The notion of obstructed sheath is introduced and explains the acceleration of energy deposition by the decreasing of the sheath potential. Then, a 2-dimensional fluid modeling of flux tubes in front of ICRF antennae allows us to calculate the rectified potentials taking into account RF polarization currents transverse to magnetic field lines. The 2-dimensional fluid code designed validates the analytical results which show that the DC rectified potential is 50% greater with polarization currents than without. Finally, the simultaneous application of an electron beam and a RF potential reveals that the potentials due to each phenomenon are additives when RF potential is much greater than beam polarization. The density depletion of polarized flux tubes in 2-dimensional PIC (particles in cells) simulations is characterized but not yet explained. (author)
Physics Bus: An Innovative Model for Public Engagement
Fox, Claire
The Physics Bus is about doing science for fun. It is an innovative model for science outreach whose mission is to awaken joy and excitement in physics for all ages and walks of life - especially those underserved by science enrichment. It is a mobile exhibition of upcycled appliances-reimagined by kids-that showcase captivating physics phenomena. Inside our spaceship-themed school bus, visitors will find: a microwave ionized-gas disco-party, fog rings that shoot from a wheelbarrow tire, a tv whose electron beam is controlled by a toy keyboard, and over 20 other themed exhibits. The Physics Bus serves a wide range of public in diverse locations from local neighborhoods, urban parks and rural schools, to cross-country destinations. Its approachable, friendly and relaxed environment allows for self-paced and self-directed interactions, providing a positive and engaging experience with science. We believe that this environment enriches lives and inspires people. In this presentation we will talk about the nuts and bolts that make this model work, how the project got started, and the resources that keep it going. We will talk about the advantages of being a grassroots and community-based organization, and how programs like this can best interface with universities. We will explain the benefits of focusing on direct interactions and why our model avoids ``teaching'' physics content with words. Situating our approach within a body of research on the value of informal science we will discuss our success in capturing and engaging our audience. By the end of this presentation we hope to broaden your perception of what makes a successful outreach program and encourage you to value and support alternative outreach models such as this one. In Collaboration with: Eva Luna, Cornell University; Erik Herman, Cornell University; Christopher Bell, Ithaca City School District.
Energy Technology Data Exchange (ETDEWEB)
Cerezo A, E. [University of Caribe, Department of Basics Sciences and Engineering, Lote 1, Manzana 1, Region 78, esq. Fracc. Tabachines, 77500 Cancun, Quintana Roo (Mexico)]. E-mail: ecerezo@unicaribe.edu.mx; Munoz C, J.L. [Department of Chemical and Nuclear Engineering, Polytechnic University of Valencia, Camino de Vera 14, 46022 Valencia (Spain)
2004-07-01
This paper presents a non-equilibrium model to describe flashing phenomena in tanks and cooling pools. The present model is based on Watanabe's work that we have extended by developing a realistic model for the growth of bubbles. We have made the corresponding venting model, continuity equation, gas and liquid phase energy conservation equations for the model. This model takes into account both drag and virtual mass force. The dynamics of bubble growth plays an important role in two-phase phenomena such as flashing. In our model the growth rate is assumed to be limited by the heat conduction in the liquid. The results of the analytic model were compared with the experimental data of Watanabe [1]. The results have shown that the present model evaluates fairly accurately the pressure evolution, the void fraction and the swelling level of a tank.
International Nuclear Information System (INIS)
Cerezo A, E.; Munoz C, J.L.
2004-01-01
This paper presents a non-equilibrium model to describe flashing phenomena in tanks and cooling pools. The present model is based on Watanabe's work that we have extended by developing a realistic model for the growth of bubbles. We have made the corresponding venting model, continuity equation, gas and liquid phase energy conservation equations for the model. This model takes into account both drag and virtual mass force. The dynamics of bubble growth plays an important role in two-phase phenomena such as flashing. In our model the growth rate is assumed to be limited by the heat conduction in the liquid. The results of the analytic model were compared with the experimental data of Watanabe [1]. The results have shown that the present model evaluates fairly accurately the pressure evolution, the void fraction and the swelling level of a tank
The Physical Internet and Business Model Innovation
Directory of Open Access Journals (Sweden)
Diane Poulin
2012-06-01
Full Text Available Building on the analogy of data packets within the Digital Internet, the Physical Internet is a concept that dramatically transforms how physical objects are designed, manufactured, and distributed. This approach is open, efficient, and sustainable beyond traditional proprietary logistical solutions, which are often plagued by inefficiencies. The Physical Internet redefines supply chain configurations, business models, and value-creation patterns. Firms are bound to be less dependent on operational scale and scope trade-offs because they will be in a position to offer novel hybrid products and services that would otherwise destroy value. Finally, logistical chains become flexible and reconfigurable in real time, thus becoming better in tune with firm strategic choices. This article focuses on the potential impact of the Physical Internet on business model innovation, both from the perspectives of Physical-Internet enabled and enabling business models.
Miao, Zheng; He, Ya-Ling; Zou, Jin-Qiang
Transport phenomena in the gas diffusion layer (GDL) are of vital importance for the operation of direct methanol fuel cells (DMFCs). In this work, a two-phase mass transport model is developed to investigate the effects of anisotropic characteristics of a GDL, including the inherent anisotropy, deformation, and electrical and thermal contact resistances, on the coupled species, charges and thermal transport processes in a DMFC. In this model, methanol crossover and non-equilibrium evaporation/condensation of water and methanol are considered. The multistep electrochemical mechanisms are used to obtain a detailed description of the kinetics of methanol oxidization reaction (MOR) in both the anode and cathode catalyst layers (CLs). The numerical results show that the anisotropy of the GDL has a great effect on the distribution of species concentration, overpotential, local current density, and temperature. The deformation of the GDL depresses the transport of species through the GDL, particularly methanol diffusion in anode GDL, but facilitates the transport of electron and the removal of heat. The electrical contact resistance plays an important role in determining the cell performance.
Energy Technology Data Exchange (ETDEWEB)
Miao, Zheng; He, Ya-Ling; Zou, Jin-Qiang [State Key Laboratory of Multiphase Flow in Power Engineering, School of Energy and Power Engineering, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China)
2010-06-01
Transport phenomena in the gas diffusion layer (GDL) are of vital importance for the operation of direct methanol fuel cells (DMFCs). In this work, a two-phase mass transport model is developed to investigate the effects of anisotropic characteristics of a GDL, including the inherent anisotropy, deformation, and electrical and thermal contact resistances, on the coupled species, charges and thermal transport processes in a DMFC. In this model, methanol crossover and non-equilibrium evaporation/condensation of water and methanol are considered. The multistep electrochemical mechanisms are used to obtain a detailed description of the kinetics of methanol oxidization reaction (MOR) in both the anode and cathode catalyst layers (CLs). The numerical results show that the anisotropy of the GDL has a great effect on the distribution of species concentration, overpotential, local current density, and temperature. The deformation of the GDL depresses the transport of species through the GDL, particularly methanol diffusion in anode GDL, but facilitates the transport of electron and the removal of heat. The electrical contact resistance plays an important role in determining the cell performance. (author)
Energy Technology Data Exchange (ETDEWEB)
Karvonen, S.; Mikkola, M. [Laboratory of Advanced Energy Systems, Helsinki University of Technology (Finland); Himanen, O. [VTT Technical Research Center of Finland, Fuel Cells, VTT (Finland); Nitta, I.
2008-12-15
The effects of inhomogeneous compression of gas diffusion layers (GDLs) on local transport phenomena within a polymer electrolyte membrane (PEM) fuel cell were studied theoretically. The inhomogeneous compression induced by the rib/channel structure of the flow field plate causes partial deformation of the GDLs and significantly affects component parameters. The results suggest that inhomogeneous compression does not significantly affect the polarisation behaviour or gas-phase mass transport. However, the effect of inhomogeneous compression on the current density distribution is evident. Local current density under the channel was substantially smaller than that under the rib when inhomogeneous compression was taken into account, while the current density distribution was fairly uniform for the model which excluded the effect of inhomogeneous compression. This is caused by the changes in the selective current path, which is determined by the combination of conductivities of components and contact resistance between them. Despite the highly uneven current distribution and variation in material parametres as a function of GDL thickness, the temperature profile was relatively even over the active area for both the modelled cases, contrary to predictions in previous studies. However, an abnormally high current density significantly accelerates deterioration of the membrane and is critical in terms of cell durability. Therefore, fuel cells should be carefully designed to minimise the harmful effects of inhomogeneous compression. (Abstract Copyright [2008], Wiley Periodicals, Inc.)
Evolutionary phenomena in galaxies
International Nuclear Information System (INIS)
Beckman, J.E.; Pagel, B.E.J.
1989-01-01
This book reviews the subject of evolutionary phenomena in galaxies, bringing together contributions by experts on all the relevant physics and astrophysics necessary to understand galaxies and how they work. The book is based on the proceedings of a conference held in July 1988 in Puerto de la Cruz, Tenerife which was timed to coincide with the first year of operation of the 4.2 m William Herschel Telescope. The broad topics covered include formation of galaxies and their ages, stellar dynamics, galactic scale gas and its role in star formation and the production and distribution of the chemical elements within galaxies. (author)
International Nuclear Information System (INIS)
Bakos, J.S.; Soerlei, Zsuzsa
1986-03-01
The invited papers of the 17. International conference on phenomena in ionized gases are published containing papers on kinetic theory of ionized gases. The topics cover plasma kinetics, plasma diagnostic methods, arc and discharge physics, magnetic properties of plasmas, new plasma models, laser-plasma physics, and transport phenomena in ionized gases. (D.Gy.)
Are Physical Education Majors Models for Fitness?
Kamla, James; Snyder, Ben; Tanner, Lori; Wash, Pamela
2012-01-01
The National Association of Sport and Physical Education (NASPE) (2002) has taken a firm stance on the importance of adequate fitness levels of physical education teachers stating that they have the responsibility to model an active lifestyle and to promote fitness behaviors. Since the NASPE declaration, national initiatives like Let's Move…
Bridging physics and biology teaching through modeling
Hoskinson, Anne-Marie; Couch, Brian A.; Zwickl, Benjamin M.; Hinko, Kathleen A.; Caballero, Marcos D.
2014-05-01
As the frontiers of biology become increasingly interdisciplinary, the physics education community has engaged in ongoing efforts to make physics classes more relevant to life science majors. These efforts are complicated by the many apparent differences between these fields, including the types of systems that each studies, the behavior of those systems, the kinds of measurements that each makes, and the role of mathematics in each field. Nonetheless, physics and biology are both sciences that rely on observations and measurements to construct models of the natural world. In this article, we propose that efforts to bridge the teaching of these two disciplines must emphasize shared scientific practices, particularly scientific modeling. We define modeling using language common to both disciplines and highlight how an understanding of the modeling process can help reconcile apparent differences between the teaching of physics and biology. We elaborate on how models can be used for explanatory, predictive, and functional purposes and present common models from each discipline demonstrating key modeling principles. By framing interdisciplinary teaching in the context of modeling, we aim to bridge physics and biology teaching and to equip students with modeling competencies applicable in any scientific discipline.
Collider physics within the standard model a primer
Altarelli, Guido
2017-01-01
With this graduate-level primer, the principles of the standard model of particle physics receive a particular skillful, personal and enduring exposition by one of the great contributors to the field. In 2013 the late Prof. Altarelli wrote: The discovery of the Higgs boson and the non-observation of new particles or exotic phenomena have made a big step towards completing the experimental confirmation of the standard model of fundamental particle interactions. It is thus a good moment for me to collect, update and improve my graduate lecture notes on quantum chromodynamics and the theory of electroweak interactions, with main focus on collider physics. I hope that these lectures can provide an introduction to the subject for the interested reader, assumed to be already familiar with quantum field theory and some basic facts in elementary particle physics as taught in undergraduate courses. “These lecture notes are a beautiful example of Guido’s unique pedagogical abilities and scientific vision”. From...
Arbabi, V.
2016-01-01
Recent advances in the realm of computational modeling of complex multiphysics phenomena in articular cartilage enabled efficient and precise determination of articular cartilage properties. However, still accurate quantification of complicated indentation and diffusion processes tying closely with
Simplified Models for LHC New Physics Searches
Alves, Daniele; Arora, Sanjay; Bai, Yang; Baumgart, Matthew; Berger, Joshua; Buckley, Matthew; Butler, Bart; Chang, Spencer; Cheng, Hsin-Chia; Cheung, Clifford; Chivukula, R.Sekhar; Cho, Won Sang; Cotta, Randy; D'Alfonso, Mariarosaria; El Hedri, Sonia; Essig, Rouven; Evans, Jared A.; Fitzpatrick, Liam; Fox, Patrick; Franceschini, Roberto; Freitas, Ayres; Gainer, James S.; Gershtein, Yuri; Gray, Richard; Gregoire, Thomas; Gripaios, Ben; Gunion, Jack; Han, Tao; Haas, Andy; Hansson, Per; Hewett, JoAnne; Hits, Dmitry; Hubisz, Jay; Izaguirre, Eder; Kaplan, Jared; Katz, Emanuel; Kilic, Can; Kim, Hyung-Do; Kitano, Ryuichiro; Koay, Sue Ann; Ko, Pyungwon; Krohn, David; Kuflik, Eric; Lewis, Ian; Lisanti, Mariangela; Liu, Tao; Liu, Zhen; Lu, Ran; Luty, Markus; Meade, Patrick; Morrissey, David; Mrenna, Stephen; Nojiri, Mihoko; Okui, Takemichi; Padhi, Sanjay; Papucci, Michele; Park, Michael; Park, Myeonghun; Perelstein, Maxim; Peskin, Michael; Phalen, Daniel; Rehermann, Keith; Rentala, Vikram; Roy, Tuhin; Ruderman, Joshua T.; Sanz, Veronica; Schmaltz, Martin; Schnetzer, Stephen; Schuster, Philip; Schwaller, Pedro; Schwartz, Matthew D.; Schwartzman, Ariel; Shao, Jing; Shelton, Jessie; Shih, David; Shu, Jing; Silverstein, Daniel; Simmons, Elizabeth; Somalwar, Sunil; Spannowsky, Michael; Spethmann, Christian; Strassler, Matthew; Su, Shufang; Tait, Tim; Thomas, Brooks; Thomas, Scott; Toro, Natalia; Volansky, Tomer; Wacker, Jay; Waltenberger, Wolfgang; Yavin, Itay; Yu, Felix; Zhao, Yue; Zurek, Kathryn
2012-01-01
This document proposes a collection of simplified models relevant to the design of new-physics searches at the LHC and the characterization of their results. Both ATLAS and CMS have already presented some results in terms of simplified models, and we encourage them to continue and expand this effort, which supplements both signature-based results and benchmark model interpretations. A simplified model is defined by an effective Lagrangian describing the interactions of a small number of new particles. Simplified models can equally well be described by a small number of masses and cross-sections. These parameters are directly related to collider physics observables, making simplified models a particularly effective framework for evaluating searches and a useful starting point for characterizing positive signals of new physics. This document serves as an official summary of the results from the "Topologies for Early LHC Searches" workshop, held at SLAC in September of 2010, the purpose of which was to develop a...
Young, Robert D.
1973-01-01
Discusses the charge independence, wavefunctions, magnetic moments, and high-energy scattering of hadrons on the basis of group theory and nonrelativistic quark model with mass spectrum calculated by first-order perturbation theory. The presentation is explainable to advanced undergraduate students. (CC)
Chen, Ting; Li, Liqing; Huang, Xiubao
2005-06-01
Physical, statistical and artificial neural network (ANN) models are established for predicting the fibre diameter of melt blown nonwovens from the processing parameters. The results show that the ANN model yields a very accurate prediction (average error of 0.013%), and a reasonably good ANN model can be achieved with relatively few data points. Because the physical model is based on the inherent physical principles of the phenomena of interest, it can yield reasonably good prediction results when experimental data are not available and the entire physical procedure is of interest. This area of research has great potential in the field of computer assisted design in melt blowing technology.
Physical model for recognition tunneling
International Nuclear Information System (INIS)
Krstić, Predrag; Ashcroft, Brian; Lindsay, Stuart
2015-01-01
Recognition tunneling (RT) identifies target molecules trapped between tunneling electrodes functionalized with recognition molecules that serve as specific chemical linkages between the metal electrodes and the trapped target molecule. Possible applications include single molecule DNA and protein sequencing. This paper addresses several fundamental aspects of RT by multiscale theory, applying both all-atom and coarse-grained DNA models: (1) we show that the magnitude of the observed currents are consistent with the results of non-equilibrium Green’s function calculations carried out on a solvated all-atom model. (2) Brownian fluctuations in hydrogen bond-lengths lead to current spikes that are similar to what is observed experimentally. (3) The frequency characteristics of these fluctuations can be used to identify the trapped molecules with a machine-learning algorithm, giving a theoretical underpinning to this new method of identifying single molecule signals. (paper)
Ontology modeling in physical asset integrity management
Yacout, Soumaya
2015-01-01
This book presents cutting-edge applications of, and up-to-date research on, ontology engineering techniques in the physical asset integrity domain. Though a survey of state-of-the-art theory and methods on ontology engineering, the authors emphasize essential topics including data integration modeling, knowledge representation, and semantic interpretation. The book also reflects novel topics dealing with the advanced problems of physical asset integrity applications such as heterogeneity, data inconsistency, and interoperability existing in design and utilization. With a distinctive focus on applications relevant in heavy industry, Ontology Modeling in Physical Asset Integrity Management is ideal for practicing industrial and mechanical engineers working in the field, as well as researchers and graduate concerned with ontology engineering in physical systems life cycles. This book also: Introduces practicing engineers, research scientists, and graduate students to ontology engineering as a modeling techniqu...
Perkins, D. H.
1986-01-01
Elementary particle physics is discussed. Status of the Standard Model of electroweak and strong interactions; phenomena beyond the Standard Model; new accelerator projects; and possible contributions from non-accelerator experiments are examined.
Rock Burst Mechanics: Insight from Physical and Mathematical Modelling
Directory of Open Access Journals (Sweden)
J. Vacek
2008-01-01
Full Text Available Rock burst processes in mines are studied by many groups active in the field of geomechanics. Physical and mathematical modelling can be used to better understand the phenomena and mechanisms involved in the bursts. In the present paper we describe both physical and mathematical models of a rock burst occurring in a gallery of a coal mine.For rock bursts (also called bumps to occur, the rock has to possess certain particular rock burst properties leading to accumulation of energy and the potential to release this energy. Such materials may be brittle, or the rock burst may arise at the interfacial zones of two parts of the rock, which have principally different material properties (e.g. in the Poíbram uranium mines.The solution is based on experimental and mathematical modelling. These two methods have to allow the problem to be studied on the basis of three presumptions:· the solution must be time dependent,· the solution must allow the creation of cracks in the rock mass,· the solution must allow an extrusion of rock into an open space (bump effect.
International Nuclear Information System (INIS)
Sethna, J.P.; Krumhansl, J.A.
1994-01-01
We have identified tweed precursors to martensitic phase transformations as a spin glass phase due to composition variations, and used simulations and exact replica theory predictions to predict diffraction peaks and model phase diagrams, and provide real space data for comparison to transmission electron micrograph images. We have used symmetry principles to derive the crack growth laws for mixed-mode brittle fracture, explaining the results for two-dimensional fracture and deriving the growth laws in three dimensions. We have used recent advances in dynamical critical phenomena to study hysteresis in disordered systems, explaining the return-point-memory effect, predicting distributions for Barkhausen noise, and elucidating the transition from athermal to burst behavior in martensites. From a nonlinear lattice-dynamical model of a first-order transition using simulations, finite-size scaling, and transfer matrix methods, it is shown that heterophase transformation precursors cannot occur in a pure homogeneous system, thus emphasizing the role of disorder in real materials. Full integration of nonlinear Landau-Ginzburg continuum theory with experimental neutron-scattering data and first-principles calculations has been carried out to compute semi-quantitative values of the energy and thickness of twin boundaries in InTl and FePd martensites
Energy Technology Data Exchange (ETDEWEB)
Sethna, J.P.; Krumhansl, J.A.
1994-08-01
We have identified tweed precursors to martensitic phase transformations as a spin glass phase due to composition variations, and used simulations and exact replica theory predictions to predict diffraction peaks and model phase diagrams, and provide real space data for comparison to transmission electron micrograph images. We have used symmetry principles to derive the crack growth laws for mixed-mode brittle fracture, explaining the results for two-dimensional fracture and deriving the growth laws in three dimensions. We have used recent advances in dynamical critical phenomena to study hysteresis in disordered systems, explaining the return-point-memory effect, predicting distributions for Barkhausen noise, and elucidating the transition from athermal to burst behavior in martensites. From a nonlinear lattice-dynamical model of a first-order transition using simulations, finite-size scaling, and transfer matrix methods, it is shown that heterophase transformation precursors cannot occur in a pure homogeneous system, thus emphasizing the role of disorder in real materials. Full integration of nonlinear Landau-Ginzburg continuum theory with experimental neutron-scattering data and first-principles calculations has been carried out to compute semi-quantitative values of the energy and thickness of twin boundaries in InTl and FePd martensites.
Utilities for high performance dispersion model PHYSIC
International Nuclear Information System (INIS)
Yamazawa, Hiromi
1992-09-01
The description and usage of the utilities for the dispersion calculation model PHYSIC were summarized. The model was developed in the study of developing high performance SPEEDI with the purpose of introducing meteorological forecast function into the environmental emergency response system. The procedure of PHYSIC calculation consists of three steps; preparation of relevant files, creation and submission of JCL, and graphic output of results. A user can carry out the above procedure with the help of the Geographical Data Processing Utility, the Model Control Utility, and the Graphic Output Utility. (author)
Energy Technology Data Exchange (ETDEWEB)
Lewis, Jennifer
2012-10-15
This scientific meeting focused on the legacy of Cathleen S. Morawetz and the impact that her scientific work on transonic flow and the non-linear wave equation has had in recent progress on different aspects of analysis for non-linear wave, kinetic and quantum transport problems associated to mathematical physics. These are areas where the elements of continuum, statistical and stochastic mechanics, and their interplay, have counterparts in the theory of existence, uniqueness and stability of the associated systems of equations and geometric constraints. It was a central event for the applied and computational analysis community focusing on Partial Differential Equations. The goal of the proposal was to honor Cathleen Morawetz, a highly successful woman in mathematics, while encouraging beginning researchers. The conference was successful in show casing the work of successful women, enhancing the visibility of women in the profession and providing role models for those just beginning their careers. The two-day conference included seven 45-minute lectures and one day of six 45-minute lectures, and a poster session for junior participants. The conference program included 19 distinguished speakers, 10 poster presentations, about 70 junior and senior participants and, of course, the participation of Cathleen Synge Morawetz. The conference celebrated Morawetz's paramount contributions to the theory of non-linear equations in gas dynamics and their impact in the current trends of nonlinear phenomena in mathematical physics, but also served as an awareness session of current women's contribution to mathematics.
Challenges of Representing Sub-Grid Physics in an Adaptive Mesh Refinement Atmospheric Model
O'Brien, T. A.; Johansen, H.; Johnson, J. N.; Rosa, D.; Benedict, J. J.; Keen, N. D.; Collins, W.; Goodfriend, E.
2015-12-01
Some of the greatest potential impacts from future climate change are tied to extreme atmospheric phenomena that are inherently multiscale, including tropical cyclones and atmospheric rivers. Extremes are challenging to simulate in conventional climate models due to existing models' coarse resolutions relative to the native length-scales of these phenomena. Studying the weather systems of interest requires an atmospheric model with sufficient local resolution, and sufficient performance for long-duration climate-change simulations. To this end, we have developed a new global climate code with adaptive spatial and temporal resolution. The dynamics are formulated using a block-structured conservative finite volume approach suitable for moist non-hydrostatic atmospheric dynamics. By using both space- and time-adaptive mesh refinement, the solver focuses computational resources only where greater accuracy is needed to resolve critical phenomena. We explore different methods for parameterizing sub-grid physics, such as microphysics, macrophysics, turbulence, and radiative transfer. In particular, we contrast the simplified physics representation of Reed and Jablonowski (2012) with the more complex physics representation used in the System for Atmospheric Modeling of Khairoutdinov and Randall (2003). We also explore the use of a novel macrophysics parameterization that is designed to be explicitly scale-aware.
Malhotra, C. P.
With increasing national and global demand for energy and concerns about the effect of fossil fuels on global climate change, there is an increasing emphasis on the development and use of renewable sources of energy. Solar cells or photovoltaics constitute an important renewable energy technology but the major impediment to their widespread adoption has been their high initial cost. Although thin-film photovoltaic semiconductors such as cadmium sulfide-cadmium telluride (CdS/CdTe) can potentially be inexpensively manufactured using large area deposition techniques such as close-spaced sublimation (CSS), their low stability has prevented them from becoming an alternative to traditional polycrystalline silicon solar cells. A key factor affecting the stability of CdS/CdTe cells is the uniformity of deposition of the thin films. Currently no models exist that can relate the processing parameters in a CSS setup with the film deposition uniformity. Central to the development of these models is a fundamental understanding of the complex transport phenomena which constitute the deposition process which include coupled conduction and radiation as well as transition regime rarefied gas flow. This thesis is aimed at filling these knowledge gaps and thereby leading to the development of the relevant models. The specific process under consideration is the CSS setup developed by the Materials Engineering Group at the Colorado State University (CSU). Initially, a 3-D radiation-conduction model of a single processing station was developed using the commercial finite-element software ABAQUS and validated against data from steady-state experiments carried out at CSU. A simplified model was then optimized for maximizing the steady-state thermal uniformity within the substrate. It was inferred that contrary to traditional top and bottom infrared lamp heating, a lamp configuration that directs heat from the periphery of the sources towards the center results in the minimum temperature
Physical Basis for Interfacial Traction-Separation Models
International Nuclear Information System (INIS)
Neville R. Moody
2002-01-01
Many weapon components contain interfaces between dissimilar materials where cracks can initiate and cause failure. In recent years many researchers in the fracture community have adopted a cohesive zone model for simulating crack propagation (based upon traction-separation relations) Sandia is implementing this model in its ASCI codes. There is, however, one important obstacle to using a cohesive zone modeling approach. At the present time traction-separation relations are chosen in an ad hoc manner. The goal of the present work is to determine a physical basis for Traction-Separation (T-U) relations. This report presents results of a program aimed at determining the dependence of such relations on adhesive and bulk properties. The work focused on epoxy/solid interfaces, although the approach is applicable to a broad range of materials. Asymmetric double cantilevered beam and free surface film nanoindentation fracture toughness tests were used to generate a unique set of data spanning length scales, applied mode mixities, and yield (plastic) zone constraint. The crucial roles of crack tip plastic zone size and interfacial adhesion were defined by varying epoxy layer thickness and using coupling agents or special self-assembled monolayers in preparing the samples. The nature of the yield zone was probed in collaborative experiments run at the Advanced Photon Source. This work provides an understanding of the major phenomena governing polymer/solid interfacial fracture and identifies the essential features that must be incorporated in a T-U based cohesive zone failure model. We believe that models using physically based T-U relations provide a more accurate and widely applicable description of interface cracking than models using ad hoc relations. Furthermore, these T-U relations provide an essential tool for using models to tailor interface properties to meet design needs
A physical model of Direct Methanol Fuel Cell anode impedance
Zago, M.; Casalegno, A.
2014-02-01
In the present work a physically based model of direct methanol fuel cell anode impedance has been developed and validated at different operating current densities. The proposed model includes the two-phase mass transport of both methanol and water through diffusion and catalyst layers and the methanol oxidation reaction involving CO adsorbed intermediate. Model simulations are in good quantitative agreement with experimental observations and permit to evaluate the origin of anode impedance features. Model results confirm that the high frequency 45° linear branch is caused by proton transport limitations within the catalyst layer and that the low frequency inductive behavior is due to surface coverage by CO reaction intermediate. Moreover model predictions elucidate the contribution to the impedance of mass transport phenomena through diffusion layer, that is relevant even at low current density and increases along the channel length. In particular liquid convective fluxes are considered as a process of pressure buildup and breakthrough at diffusion layer intersecting fibers, resulting in a discontinuous phenomenon. By means of this intermittent description it is possible to correctly reproduce mass transport limitations through diffusion layers, that manifest themselves as a second arch superimposed to the first one, peculiar of kinetic losses.
Simplified Models for LHC New Physics Searches
International Nuclear Information System (INIS)
Alves, Daniele; Arkani-Hamed, Nima; Arora, Sanjay; Bai, Yang; Baumgart, Matthew; Berger, Joshua; Butler, Bart; Chang, Spencer; Cheng, Hsin-Chia; Cheung, Clifford; Chivukula, R. Sekhar; Cho, Won Sang; Cotta, Randy; D'Alfonso, Mariarosaria; El Hedri, Sonia; Essig, Rouven; Fitzpatrick, Liam; Fox, Patrick; Franceschini, Roberto
2012-01-01
This document proposes a collection of simplified models relevant to the design of new-physics searches at the LHC and the characterization of their results. Both ATLAS and CMS have already presented some results in terms of simplified models, and we encourage them to continue and expand this effort, which supplements both signature-based results and benchmark model interpretations. A simplified model is defined by an effective Lagrangian describing the interactions of a small number of new particles. Simplified models can equally well be described by a small number of masses and cross-sections. These parameters are directly related to collider physics observables, making simplified models a particularly effective framework for evaluating searches and a useful starting point for characterizing positive signals of new physics. This document serves as an official summary of the results from the 'Topologies for Early LHC Searches' workshop, held at SLAC in September of 2010, the purpose of which was to develop a set of representative models that can be used to cover all relevant phase space in experimental searches. Particular emphasis is placed on searches relevant for the first ∼ 50-500 pb -1 of data and those motivated by supersymmetric models. This note largely summarizes material posted at http://lhcnewphysics.org/, which includes simplified model definitions, Monte Carlo material, and supporting contacts within the theory community. We also comment on future developments that may be useful as more data is gathered and analyzed by the experiments.
Simplified Models for LHC New Physics Searches
Energy Technology Data Exchange (ETDEWEB)
Alves, Daniele; /SLAC; Arkani-Hamed, Nima; /Princeton, Inst. Advanced Study; Arora, Sanjay; /Rutgers U., Piscataway; Bai, Yang; /SLAC; Baumgart, Matthew; /Johns Hopkins U.; Berger, Joshua; /Cornell U., Phys. Dept.; Buckley, Matthew; /Fermilab; Butler, Bart; /SLAC; Chang, Spencer; /Oregon U. /UC, Davis; Cheng, Hsin-Chia; /UC, Davis; Cheung, Clifford; /UC, Berkeley; Chivukula, R.Sekhar; /Michigan State U.; Cho, Won Sang; /Tokyo U.; Cotta, Randy; /SLAC; D' Alfonso, Mariarosaria; /UC, Santa Barbara; El Hedri, Sonia; /SLAC; Essig, Rouven, (ed.); /SLAC; Evans, Jared A.; /UC, Davis; Fitzpatrick, Liam; /Boston U.; Fox, Patrick; /Fermilab; Franceschini, Roberto; /LPHE, Lausanne /Pittsburgh U. /Argonne /Northwestern U. /Rutgers U., Piscataway /Rutgers U., Piscataway /Carleton U. /CERN /UC, Davis /Wisconsin U., Madison /SLAC /SLAC /SLAC /Rutgers U., Piscataway /Syracuse U. /SLAC /SLAC /Boston U. /Rutgers U., Piscataway /Seoul Natl. U. /Tohoku U. /UC, Santa Barbara /Korea Inst. Advanced Study, Seoul /Harvard U., Phys. Dept. /Michigan U. /Wisconsin U., Madison /Princeton U. /UC, Santa Barbara /Wisconsin U., Madison /Michigan U. /UC, Davis /SUNY, Stony Brook /TRIUMF; /more authors..
2012-06-01
This document proposes a collection of simplified models relevant to the design of new-physics searches at the LHC and the characterization of their results. Both ATLAS and CMS have already presented some results in terms of simplified models, and we encourage them to continue and expand this effort, which supplements both signature-based results and benchmark model interpretations. A simplified model is defined by an effective Lagrangian describing the interactions of a small number of new particles. Simplified models can equally well be described by a small number of masses and cross-sections. These parameters are directly related to collider physics observables, making simplified models a particularly effective framework for evaluating searches and a useful starting point for characterizing positive signals of new physics. This document serves as an official summary of the results from the 'Topologies for Early LHC Searches' workshop, held at SLAC in September of 2010, the purpose of which was to develop a set of representative models that can be used to cover all relevant phase space in experimental searches. Particular emphasis is placed on searches relevant for the first {approx} 50-500 pb{sup -1} of data and those motivated by supersymmetric models. This note largely summarizes material posted at http://lhcnewphysics.org/, which includes simplified model definitions, Monte Carlo material, and supporting contacts within the theory community. We also comment on future developments that may be useful as more data is gathered and analyzed by the experiments.
PHYSICAL EDUCATION - PHYSICAL CULTURE. TWO MODELS, TWO DIDACTIC
Directory of Open Access Journals (Sweden)
Manuel Vizuete Carrizosa
2014-11-01
The survival of these conflicting positions and their interests and different views on education, in a lengthy space of time, as a consequence threw two teaching approaches and two different educational models, in which the objectives and content of education differ , and with them the forms and methods of teaching. The need to define the cultural and educational approach, in every time and place, is now a pressing need and challenge the processes of teacher training, as responsible for shaping an advanced physical education, adjusted to the time and place, the interests and needs of citizens and the democratic values of modern society.
PHYSICAL EDUCATION - PHYSICAL CULTURE. TWO MODELS, TWO DIDACTIC
Directory of Open Access Journals (Sweden)
Manuel Vizuete Carrizosa
2014-10-01
Full Text Available Physical Education is currently facing a number of problems that are rooted in the identity crisis prompted by the spread of the professional group, the confrontation of ideas from the scientific community and the competing interests of different political and social areas, compared to which physical education has failed, or unable, to react in time. The political and ideological confrontation that characterized the twentieth century gave us two forms, each with a consistent ideological position, in which the body as a subject of education was understood from two different positions: one set from the left and communism and another, from Western democratic societies.The survival of these conflicting positions and their interests and different views on education, in a lengthy space of time, as a consequence threw two teaching approaches and two different educational models, in which the objectives and content of education differ , and with them the forms and methods of teaching. The need to define the cultural and educational approach, in every time and place, is now a pressing need and challenge the processes of teacher training, as responsible for shaping an advanced physical education, adjusted to the time and place, the interests and needs of citizens and the democratic values of modern society.
Lawrance, R
1972-01-01
Solid State Phenomena explores the fundamentals of the structure and their influence on the properties of solids. This book is composed of five chapters that focus on the electrical and thermal conductivities of crystalline solids. Chapter 1 describes the nature of solids, particularly metals and crystalline materials. This chapter also presents a model to evaluate crystal structure, the forces between atom pairs, and the mechanism of plastic and elastic deformation. Chapter 2 demonstrates random vibrations of atoms in a solid using a one-dimensional array, while Chapter 3 examines the resista
Plasma simulation studies using multilevel physics models
International Nuclear Information System (INIS)
Park, W.; Belova, E.V.; Fu, G.Y.
2000-01-01
The question of how to proceed toward ever more realistic plasma simulation studies using ever increasing computing power is addressed. The answer presented here is the M3D (Multilevel 3D) project, which has developed a code package with a hierarchy of physics levels that resolve increasingly complete subsets of phase-spaces and are thus increasingly more realistic. The rationale for the multilevel physics models is given. Each physics level is described and examples of its application are given. The existing physics levels are fluid models (3D configuration space), namely magnetohydrodynamic (MHD) and two-fluids; and hybrid models, namely gyrokinetic-energetic-particle/MHD (5D energetic particle phase-space), gyrokinetic-particle-ion/fluid-electron (5D ion phase-space), and full-kinetic-particle-ion/fluid-electron level (6D ion phase-space). Resolving electron phase-space (5D or 6D) remains a future project. Phase-space-fluid models are not used in favor of delta f particle models. A practical and accurate nonlinear fluid closure for noncollisional plasmas seems not likely in the near future
Plasma simulation studies using multilevel physics models
Energy Technology Data Exchange (ETDEWEB)
Park, W.; Belova, E.V.; Fu, G.Y. [and others
2000-01-19
The question of how to proceed toward ever more realistic plasma simulation studies using ever increasing computing power is addressed. The answer presented here is the M3D (Multilevel 3D) project, which has developed a code package with a hierarchy of physics levels that resolve increasingly complete subsets of phase-spaces and are thus increasingly more realistic. The rationale for the multilevel physics models is given. Each physics level is described and examples of its application are given. The existing physics levels are fluid models (3D configuration space), namely magnetohydrodynamic (MHD) and two-fluids; and hybrid models, namely gyrokinetic-energetic-particle/MHD (5D energetic particle phase-space), gyrokinetic-particle-ion/fluid-electron (5D ion phase-space), and full-kinetic-particle-ion/fluid-electron level (6D ion phase-space). Resolving electron phase-space (5D or 6D) remains a future project. Phase-space-fluid models are not used in favor of delta f particle models. A practical and accurate nonlinear fluid closure for noncollisional plasmas seems not likely in the near future.
Advances in the physics modelling of CANDU liquid injection shutdown systems
International Nuclear Information System (INIS)
Smith, H.J.; Robinson, R.; Guertin, C.
1993-01-01
The physics modelling of liquid poison injection shutdown systems in CANDU reactors accounts for the major phenomena taking place by combining the effects of both moderator hydraulics and neutronics. This paper describes the advances in the physics modelling of liquid poison injection shutdown systems (LISS), discusses some of the effects of the more realistic modelling, and briefly describes the automation methodology. Modifications to the LISS methodology have improved the realism of the physics modelling, showing that the previous methodology significantly overestimated energy deposition during the simulation of a loss of coolant transient in Bruce A, by overestimating the reactivity transient. Furthermore, the automation of the modelling process has reduced the time needed to carry put LISS evaluations to the same level as required for shutoff-rod evaluations, while at the same time minimizing the amount of input, and providing a method for tracing all files used, thus adding a level of quality assurance to the calculation. 5 refs., 11 figs
Topos models for physics and topos theory
Energy Technology Data Exchange (ETDEWEB)
Wolters, Sander, E-mail: s.wolters@math.ru.nl [Radboud Universiteit Nijmegen, Institute for Mathematics, Astrophysics, and Particle Physics (Netherlands)
2014-08-15
What is the role of topos theory in the topos models for quantum theory as used by Isham, Butterfield, Döring, Heunen, Landsman, Spitters, and others? In other words, what is the interplay between physical motivation for the models and the mathematical framework used in these models? Concretely, we show that the presheaf topos model of Butterfield, Isham, and Döring resembles classical physics when viewed from the internal language of the presheaf topos, similar to the copresheaf topos model of Heunen, Landsman, and Spitters. Both the presheaf and copresheaf models provide a “quantum logic” in the form of a complete Heyting algebra. Although these algebras are natural from a topos theoretic stance, we seek a physical interpretation for the logical operations. Finally, we investigate dynamics. In particular, we describe how an automorphism on the operator algebra induces a homeomorphism (or isomorphism of locales) on the associated state spaces of the topos models, and how elementary propositions and truth values transform under the action of this homeomorphism. Also with dynamics the focus is on the internal perspective of the topos.
Directory of Open Access Journals (Sweden)
Guo-Li Chiou
2013-05-01
Full Text Available Although prediction is claimed to be a prime function of mental models, to what extent students can run their mental models to make predictions of physical phenomena remains uncertain. The purpose of this study, therefore, was first to investigate 30 physics students’ mental models of heat convection, and then to examine the relationship between their mental models and predictions of convection-related phenomena. A series of semistructured interviews was conducted to probe the participants’ mental models and predictions of heat convection, and the constant comparative method was adopted for data analysis. The results reveal that the participants held a variety of mental models of heat convection, and nearly half held flawed mental models rather than a scientifically compatible one. In addition, while many participants attempted to run their mental models to make a prediction at the beginning stage of solving an interview problem, the relationship between the models and predictions became increasingly complex as the problem solving process continued. The relationships between mental models and predictions, however, could be better understood by considering the completeness of a mental model, the scale of analyzing mental models, and the retrieval of different formats of mental representations.
Energy Technology Data Exchange (ETDEWEB)
Maher, A.R.; Al-Baghdadi, S. [International Technological Univ., London (United Kingdom). Dept. of Mechanical Engineering; Haroun, A.K.; Al-Janabi, S. [Babylon Univ., Babylon (Iraq). Dept. of Mechanical Engineering
2007-07-01
Fuel cell technology is expected to play an important role in meeting the growing demand for distributed generation because it can convert the chemical energy of a clean fuel directly into electrical energy. An operating fuel cell has varying local conditions of temperature, humidity, and power generation across the active area of the fuel cell in 3D. This paper presented a model that was developed to improve the basic understanding of the transport phenomena and thermal stresses in PEM fuel cells, and to investigate the behaviour of polymer membrane under hygro and thermal stresses during the cell operation. This comprehensive 3D, multiphase, non-isothermal model accounts for the major transport phenomena in a PEM fuel cell, notably convective and diffusive heat and mass transfer; electrode kinetics; transport and phase change mechanism of water; and potential fields. The model accounts for the liquid water flux inside the gas diffusion layers by viscous and capillary forces and can therefore predict the amount of liquid water inside the gas diffusion layers. This study also investigated the key parameters affecting fuel cell performance including geometry, materials and operating conditions. The model considers the many interacting, complex electrochemical, transport phenomena, thermal stresses and deformation that cannot be studied experimentally. It was concluded that the model can provide a computer-aided tool for the design and optimization of future fuel cells with much higher power density and lower cost. 21 refs., 2 tabs., 14 figs.
Physical and mathematical modelling of extrusion processes
DEFF Research Database (Denmark)
Arentoft, Mogens; Gronostajski, Z.; Niechajowics, A.
2000-01-01
The main objective of the work is to study the extrusion process using physical modelling and to compare the findings of the study with finite element predictions. The possibilities and advantages of the simultaneous application of both of these methods for the analysis of metal forming processes...
Why supersymmetry? Physics beyond the standard model
Indian Academy of Sciences (India)
The Naturalness Principle as a requirement that the heavy mass scales decouple from the physics of light mass scales is reviewed. In quantum field theories containing {\\em elementary} scalar fields, such as the StandardModel of electroweak interactions containing the Higgs particle, mass of the scalar field is not a natural ...
Protein Folding: Search for Basic Physical Models
Directory of Open Access Journals (Sweden)
Ivan Y. Torshin
2003-01-01
Full Text Available How a unique three-dimensional structure is rapidly formed from the linear sequence of a polypeptide is one of the important questions in contemporary science. Apart from biological context of in vivo protein folding (which has been studied only for a few proteins, the roles of the fundamental physical forces in the in vitro folding remain largely unstudied. Despite a degree of success in using descriptions based on statistical and/or thermodynamic approaches, few of the current models explicitly include more basic physical forces (such as electrostatics and Van Der Waals forces. Moreover, the present-day models rarely take into account that the protein folding is, essentially, a rapid process that produces a highly specific architecture. This review considers several physical models that may provide more direct links between sequence and tertiary structure in terms of the physical forces. In particular, elaboration of such simple models is likely to produce extremely effective computational techniques with value for modern genomics.
A physical model of the intrathoracic stomach
Bemelman, W. A.; Verburg, J.; Brummelkamp, W. H.; Klopper, P. J.
1988-01-01
To determine whether duodenogastric reflux into the thoracic stomach could be caused by the transmission of negative intrapleural pressure fluctuations into the gastric lumen, a physical model is described and an equation calculated Pm + Pa - Pmb - (Sv.Pmb.Vmb/Pm) = Ppl - Sv.Vmb where Pm is
Why supersymmetry? Physics beyond the standard model
Indian Academy of Sciences (India)
2016-08-23
Aug 23, 2016 ... Abstract. The Naturalness Principle as a requirement that the heavy mass scales decouple from the physics of light mass scales is reviewed. In quantum field theories containing elementary scalar fields, such as the Standard. Model of electroweak interactions containing the Higgs particle, mass of the ...
Continuum Modeling in the Physical Sciences
Groesen, van E.; Molenaar, J.
2007-01-01
Mathematical modeling—the ability to apply mathematical concepts and techniques to real-life systems—has expanded considerably over the last decades, making it impossible to cover all of its aspects in one course or textbook. Continuum Modeling in the Physical Sciences provides an extensive
Consolo, Filippo; Fiore, Gianfranco B; Truscello, Silvia; Caronna, Marco; Morbiducci, Umberto; Montevecchi, Franco M; Redaelli, Alberto
2009-03-01
A comprehensive computational study modelling the operation of a rotating hollow-fiber bioreactor for artificial liver (BAL) was performed to explore the interactions between the oxygenated culture medium and the cultured hepatocytes. Computational fluid dynamics investigations were carried out using two-dimensional (2D) and 3D time-dependent numerical simulations, integrating calculations of diffusion, convection, and multiphase fluid dynamics. The analysis was aimed at determining the rotational speed value of the chamber to ensure homogenous distribution of the floating microcarrier-attached aggregated cells (microCAACs) and avoid their sedimentation and excessive packing, analyzing oxygen (O(2)) delivery and cellular O(2) consumption as an index of cellular metabolic activity, and analyzing the fluid-induced mechanical stress experienced by cells. According to our results, homogeneous distribution of cells is reached at a rotational speed of 30 rpm; spreading of cellular concentration at around the initial value of 12% was limited (median = 11.97%, 5th percentile = 10.94%, 95th percentile = 13.2%), resulting in uniform suspension of microCAACs, which did not appear to be excessively packed. Mixing within the rotating fluid caused a maximum fluid-induced stress value of 0.05 Pa, which was neither endangering for liver-specific functions of cultured cells, nor causing disruption of the floating aggregates. Moreover, an inlet medium flow rate of 200 mL/m with a partial pressure of oxygen (pO(2)) value of 160 mmHg was found to guarantee an adequate O(2) supply for the hepatocytes (2.7 x 10(8) hepatocytes are simulated); under such conditions, the minimum pO(2) value (23 mmHg) is above the critical threshold value, causing the onset of cellular hypoxia (10 mmHg). We proved that numerical simulation of transport phenomena is a valuable tool for the computer-aided design of BALs, helping overcome the unsolved issues in optimizing the cell-environment conditioning
García-Salaberri, Pablo A.; Vera, Marcos; Iglesias, Immaculada
2014-01-01
An isothermal two-phase 2D/1D across-the-channel model for the anode of a liquid-feed Direct Methanol Fuel Cell (DMFC) is presented. The model takes into account the effects of the inhomogeneous assembly compression of the Gas Diffusion Layer (GDL), including the spatial variations of porosity, diffusivity, permeability, capillary pressure, and electrical conductivity. The effective anisotropic properties of the GDL are evaluated from empirical data reported in the literature corresponding to Toray carbon paper TGP-H series. Multiphase transport is modeled according to the classical theory of porous media (two-fluid model), considering the effect of non-equilibrium evaporation and condensation of methanol and water. The numerical results evidence that the hydrophobic Leverett J-function approach is physically inconsistent to describe capillary transport in the anode of a DMFC when assembly compression effects are considered. In contrast, more realistic results are obtained when GDL-specific capillary pressure curves reflecting the mixed-wettability characteristics of GDLs are taken into account. The gas coverage factor at the GDL/channel interface also exhibits a strong influence on the gas-void fraction distribution in the GDL, which in turn depends on the relative importance between the capillary resistance induced by the inhomogeneous compression, Rc(∝ ∂pc / ∂ ε) , and the capillary diffusivity, Dbarc(∝ ∂pc / ∂ s) .
Yuan, Jinliang; Yu, Jong-Sung; Sundén, Bengt
2015-03-01
During recent years intensive research activities involving both experimental and modeling approaches have appeared for different aspects of Lithium-air (Li-air) battery. Multi-phase transport phenomena including dissolved oxygen and lithium ions (Li+) in the liquid electrolyte, as well as electrons in the solid materials, are strongly coupled with the porous structures and various reactions, particularly the solid product grown in the porous cathode during battery discharge. Understanding the mechanisms of transport phenomena and accurate evaluation of effective transport properties are significant for improving the battery capacities and design, especially at high rate conditions. In this paper, the transport governing equations commonly used for macroscopic continuum models at porous-average level are outlined and highlighted, with a purpose to provide a general overview of the validity and the limitation of these approaches. The most often used models in the open literature are reviewed and discussed focusing on the effective properties involving tortuosity factors, solid product morphologies, as well as effects on the void space clogging, surface area reduction and passivation. Comments and suggestions are also provided for better understanding of multi-phase transport phenomena and implementation of the detailed models for solid product generation and morphology growth in Li-air battery cathodes.
Photonic Crystals Physics and Practical Modeling
Sukhoivanov, Igor A
2009-01-01
The great interest in photonic crystals and their applications in the past decade requires a thorough training of students and professionals who can practically apply the knowledge of physics of photonic crystals together with skills of independent calculation of basic characteristics of photonic crystals and modelling of various photonic crystal elements for application in all-optical communication systems. This book combines basic backgrounds in fiber and integrated optics with detailed analysis of mathematical models for 1D, 2D and 3D photonic crystals and microstructured fibers, as well as with descriptions of real algorithms and codes for practical realization of the models.
Statistical physics of pairwise probability models
DEFF Research Database (Denmark)
Roudi, Yasser; Aurell, Erik; Hertz, John
2009-01-01
(dansk abstrakt findes ikke) Statistical models for describing the probability distribution over the states of biological systems are commonly used for dimensional reduction. Among these models, pairwise models are very attractive in part because they can be fit using a reasonable amount of data......: knowledge of the means and correlations between pairs of elements in the system is sufficient. Not surprisingly, then, using pairwise models for studying neural data has been the focus of many studies in recent years. In this paper, we describe how tools from statistical physics can be employed for studying...... and using pairwise models. We build on our previous work on the subject and study the relation between different methods for fitting these models and evaluating their quality. In particular, using data from simulated cortical networks we study how the quality of various approximate methods for inferring...
Electroweak penguin decays as probes of physics beyond the Standard Model
CERN. Geneva
2012-01-01
Electroweak penguin decays are sensitive to new, virtual particles and therefore offer a unique window on any physics beyond the Standard Model. In the B sector, penguin decays such as B0->K*0mu+mu- give a number of measurable quantities which can be precisely predicted by theory. The LHCb experiment has made the world's most precise measurements of this and several other related decays. These measurements give constraints on any new physics phenomena contributing to the relevant loop processes at mass scales well in excess of those that can be accessed by direct searches. The recent experimental progress of such measurements will be presented.
Nomeli, M. A.; Alizadehnomeli, M.
2017-12-01
A long-term geochemical modeling of CO2 sequestration is carried out in a single fracture to investigate its impact on CO2 transport and storage capacity. We model the fracture by considering flow of CO2 between finite plates. We study the physics and the critical time of blockage for a fracture to interpret the results. To this end, we employ direct numerical simulation tools and algorithms to simulate incompressible flow along with necessary transport equations that capture the kinetics of relevant chemical reactions. The numerical model is based on a finite volume method using a sequential non-iterative approach. It is found that mineral precipitation has an important effect on reservoir porosity and permeability. According to the simulations, the flow of injected CO2 in the fracture is controlled by changes in the pore-scale permeability close to the fracture inlet. The fracture ceases to be a fluid channel because of the precipitation of minerals. In addition, using parameter analysis we also determine the effect of various mineral precipitates on porosity of fractures.
Nomeli, Mohammad; Riaz, Amir
2017-11-01
Direct numerical simulation of reactive flow and a long-term geochemical modeling of CO2 sequestration is carried out in a fractured media to investigate its impact on CO2 transport and storage capacity. The fracture is modeled by considering flow of CO2 between finite plates. We study the physics and the critical time of blockage for a fracture to interpret the results. To this end, we employ direct numerical simulation tools and algorithms to simulate incompressible flow along with necessary transport equations that capture the kinetics of relevant chemical reactions. The numerical model is based on a finite volume method using a sequential non-iterative approach. It is found that the reactive transport of minerals has an important effect on reservoir porosity and permeability. According to the simulations, the flow of injected CO2 in the fracture is controlled by changes in the pore-scale permeability. The fracture ceases to be a fluid channel due to geochemical reactions of minerals. In addition, using parameter analysis we also determine the effect of various reaction kinetics on permeability of porous media.
Thermal transport phenomena in nanoparticle suspensions
International Nuclear Information System (INIS)
Cardellini, Annalisa; Fasano, Matteo; Bozorg Bigdeli, Masoud; Chiavazzo, Eliodoro; Asinari, Pietro
2016-01-01
Nanoparticle suspensions in liquids have received great attention, as they may offer an approach to enhance thermophysical properties of base fluids. A good variety of applications in engineering and biomedicine has been investigated with the aim of exploiting the above potential. However, the multiscale nature of nanosuspensions raises several issues in defining a comprehensive modelling framework, incorporating relevant molecular details and much larger scale phenomena, such as particle aggregation and their dynamics. The objectives of the present topical review is to report and discuss the main heat and mass transport phenomena ruling macroscopic behaviour of nanosuspensions, arising from molecular details. Relevant experimental results are included and properly put in the context of recent observations and theoretical studies, which solved long-standing debates about thermophysical properties enhancement. Major transport phenomena are discussed and in-depth analysis is carried out for highlighting the role of geometrical (nanoparticle shape, size, aggregation, concentration), chemical (pH, surfactants, functionalization) and physical parameters (temperature, density). We finally overview several computational techniques available at different scales with the aim of drawing the attention on the need for truly multiscale predictive models. This may help the development of next-generation nanoparticle suspensions and their rational use in thermal applications. (topical review)
Thermal transport phenomena in nanoparticle suspensions
Cardellini, Annalisa; Fasano, Matteo; Bozorg Bigdeli, Masoud; Chiavazzo, Eliodoro; Asinari, Pietro
2016-12-01
Nanoparticle suspensions in liquids have received great attention, as they may offer an approach to enhance thermophysical properties of base fluids. A good variety of applications in engineering and biomedicine has been investigated with the aim of exploiting the above potential. However, the multiscale nature of nanosuspensions raises several issues in defining a comprehensive modelling framework, incorporating relevant molecular details and much larger scale phenomena, such as particle aggregation and their dynamics. The objectives of the present topical review is to report and discuss the main heat and mass transport phenomena ruling macroscopic behaviour of nanosuspensions, arising from molecular details. Relevant experimental results are included and properly put in the context of recent observations and theoretical studies, which solved long-standing debates about thermophysical properties enhancement. Major transport phenomena are discussed and in-depth analysis is carried out for highlighting the role of geometrical (nanoparticle shape, size, aggregation, concentration), chemical (pH, surfactants, functionalization) and physical parameters (temperature, density). We finally overview several computational techniques available at different scales with the aim of drawing the attention on the need for truly multiscale predictive models. This may help the development of next-generation nanoparticle suspensions and their rational use in thermal applications.
Modelling of thermalhydraulics and reactor physics in simulators
International Nuclear Information System (INIS)
Miettinen, J.
1994-01-01
The evolution of thermalhydraulic analysis methods for analysis and simulator purposes has brought closer the thermohydraulic models in both application areas. In large analysis codes like RELAP5, TRAC, CATHARE and ATHLET the accuracy for calculating complicated phenomena has been emphasized, but in spite of large development efforts many generic problems remain unsolved. For simulator purposes fast running codes have been developed and these include only limited assessment efforts. But these codes have more simulator friendly features than large codes, like portability and modular code structure. In this respect the simulator experiences with SMABRE code are discussed. Both large analysis codes and special simulator codes have their advances in simulator applications. The evolution of reactor physical calculation methods in simulator applications has started from simple point kinetic models. For analysis purposes accurate 1-D and 3-D codes have been developed being capable for fast and complicated transients. For simulator purposes capability for simulation of instruments has been emphasized, but the dynamic simulation capability has been less significant. The approaches for 3-dimensionality in simulators requires still quite much development, before the analysis accuracy is reached. (orig.) (8 refs., 2 figs., 2 tabs.)
Physical chemistry and modelling of the sintering of actinide oxides
International Nuclear Information System (INIS)
Lechelle, Jacques
2013-01-01
This report gives a synthesis of the work I have carried out or to which I have numerically contributed to from 1996 up to 2012 in the Department of Plutonium Uranium and minor Actinides in Cadarache CEA Center. Their main goal is the study and the modeling of the sintering process of nuclear fuels which is the unifying thread of this document. Both in order to take into account the physical and chemical features of the actinide bearing oxide material and in order to combine the different transport phenomena leading to sintering, a sub-granular scale model is under development. Extension to a varying chemical composition as well as exchanges with the gaseous phase are foreseen. A simulation on a larger scale (pellet scale) is ongoing in the framework of a PhD thesis. Validation means have been tested with (U,Pu)O 2 material on the scale of the pellet (Small Angle Neutron Diffusion), on the scale of powder granules (X-Ray High Resolution Micro-Tomography) and with CeO 2 at the 'Institut de Chimie Separative' in Marcoule on a single crystal scale (Environmental Scanning Electron Microscope). The required microstructure homogeneity for nuclear fuels has led to a campaign of experimental studies about the role of Cr 2 O 3 as a sintering aid. Whole of these studies improve our understanding of fuel sintering and hence leads to an improved mastering of this process. (author) [fr
Nonlinear dynamical phenomena in liquid crystals
International Nuclear Information System (INIS)
Wang, X.Y.; Sun, Z.M.
1988-09-01
Because of the existence of the orientational order and anisotropy in liquid crystals, strong nonlinear phenomena and singular behaviors, such as solitary wave, transient periodic structure, chaos, fractal and viscous fingering, can be excited by a very small disturbance. These phenomena and behaviors are in connection with physics, biology and mathematics. 12 refs, 6 figs
B physics beyond the Standard Model
International Nuclear Information System (INIS)
Hewett, J.A.L.
1997-12-01
The ability of present and future experiments to test the Standard Model in the B meson sector is described. The authors examine the loop effects of new interactions in flavor changing neutral current B decays and in Z → b anti b, concentrating on supersymmetry and the left-right symmetric model as specific examples of new physics scenarios. The procedure for performing a global fit to the Wilson coefficients which describe b → s transitions is outlined, and the results of such a fit from Monte Carlo generated data is compared to the predictions of the two sample new physics scenarios. A fit to the Zb anti b couplings from present data is also given
LHC Higgs physics beyond the Standard Model
Energy Technology Data Exchange (ETDEWEB)
Spannowsky, M.
2007-09-22
The Large Hadron Collider (LHC) at CERN will be able to perform proton collisions at a much higher center-of-mass energy and luminosity than any other collider. Its main purpose is to detect the Higgs boson, the last unobserved particle of the Standard Model, explaining the riddle of the origin of mass. Studies have shown, that for the whole allowed region of the Higgs mass processes exist to detect the Higgs at the LHC. However, the Standard Model cannot be a theory of everything and is not able to provide a complete understanding of physics. It is at most an effective theory up to a presently unknown energy scale. Hence, extensions of the Standard Model are necessary which can affect the Higgs-boson signals. We discuss these effects in two popular extensions of the Standard Model: the Minimal Supersymmetric Standard Model (MSSM) and the Standard Model with four generations (SM4G). Constraints on these models come predominantly from flavor physics and electroweak precision measurements. We show, that the SM4G is still viable and that a fourth generation has strong impact on decay and production processes of the Higgs boson. Furthermore, we study the charged Higgs boson in the MSSM, yielding a clear signal for physics beyond the Standard Model. For small tan {beta} in minimal flavor violation (MFV) no processes for the detection of a charged Higgs boson do exist at the LHC. However, MFV is just motivated by the experimental agreement of results from flavor physics with Standard Model predictions, but not by any basic theoretical consideration. In this thesis, we calculate charged Higgs boson production cross sections beyond the assumption of MFV, where a large number of free parameters is present in the MSSM. We find that the soft-breaking parameters which enhance the charged-Higgs boson production most are just bound to large values, e.g. by rare B-meson decays. Although the charged-Higgs boson cross sections beyond MFV turn out to be sizeable, only a detailed
LHC Higgs physics beyond the Standard Model
International Nuclear Information System (INIS)
Spannowsky, M.
2007-01-01
The Large Hadron Collider (LHC) at CERN will be able to perform proton collisions at a much higher center-of-mass energy and luminosity than any other collider. Its main purpose is to detect the Higgs boson, the last unobserved particle of the Standard Model, explaining the riddle of the origin of mass. Studies have shown, that for the whole allowed region of the Higgs mass processes exist to detect the Higgs at the LHC. However, the Standard Model cannot be a theory of everything and is not able to provide a complete understanding of physics. It is at most an effective theory up to a presently unknown energy scale. Hence, extensions of the Standard Model are necessary which can affect the Higgs-boson signals. We discuss these effects in two popular extensions of the Standard Model: the Minimal Supersymmetric Standard Model (MSSM) and the Standard Model with four generations (SM4G). Constraints on these models come predominantly from flavor physics and electroweak precision measurements. We show, that the SM4G is still viable and that a fourth generation has strong impact on decay and production processes of the Higgs boson. Furthermore, we study the charged Higgs boson in the MSSM, yielding a clear signal for physics beyond the Standard Model. For small tan β in minimal flavor violation (MFV) no processes for the detection of a charged Higgs boson do exist at the LHC. However, MFV is just motivated by the experimental agreement of results from flavor physics with Standard Model predictions, but not by any basic theoretical consideration. In this thesis, we calculate charged Higgs boson production cross sections beyond the assumption of MFV, where a large number of free parameters is present in the MSSM. We find that the soft-breaking parameters which enhance the charged-Higgs boson production most are just bound to large values, e.g. by rare B-meson decays. Although the charged-Higgs boson cross sections beyond MFV turn out to be sizeable, only a detailed
Statistical physics of pairwise probability models
Directory of Open Access Journals (Sweden)
Yasser Roudi
2009-11-01
Full Text Available Statistical models for describing the probability distribution over the states of biological systems are commonly used for dimensional reduction. Among these models, pairwise models are very attractive in part because they can be fit using a reasonable amount of data: knowledge of the means and correlations between pairs of elements in the system is sufficient. Not surprisingly, then, using pairwise models for studying neural data has been the focus of many studies in recent years. In this paper, we describe how tools from statistical physics can be employed for studying and using pairwise models. We build on our previous work on the subject and study the relation between different methods for fitting these models and evaluating their quality. In particular, using data from simulated cortical networks we study how the quality of various approximate methods for inferring the parameters in a pairwise model depends on the time bin chosen for binning the data. We also study the effect of the size of the time bin on the model quality itself, again using simulated data. We show that using finer time bins increases the quality of the pairwise model. We offer new ways of deriving the expressions reported in our previous work for assessing the quality of pairwise models.
Physical models on discrete space and time
International Nuclear Information System (INIS)
Lorente, M.
1986-01-01
The idea of space and time quantum operators with a discrete spectrum has been proposed frequently since the discovery that some physical quantities exhibit measured values that are multiples of fundamental units. This paper first reviews a number of these physical models. They are: the method of finite elements proposed by Bender et al; the quantum field theory model on discrete space-time proposed by Yamamoto; the finite dimensional quantum mechanics approach proposed by Santhanam et al; the idea of space-time as lattices of n-simplices proposed by Kaplunovsky et al; and the theory of elementary processes proposed by Weizsaecker and his colleagues. The paper then presents a model proposed by the authors and based on the (n+1)-dimensional space-time lattice where fundamental entities interact among themselves 1 to 2n in order to build up a n-dimensional cubic lattice as a ground field where the physical interactions take place. The space-time coordinates are nothing more than the labelling of the ground field and take only discrete values. 11 references
A Quasi Model Independent Search for New High $p_T$ Physics at D0
Energy Technology Data Exchange (ETDEWEB)
Knuteson, Bruce Owen [UC, Berkeley, Astron. Dept.
2000-12-01
We present a new quasi-model-independent strategy ("Sleuth") for searching for physics beyond the standard model. We define final states to be studied, and construct a rule that identities a set of relevant variables for any particular final state. A novel algorithm searches for regions of excess in those variables and quantities the significance of any detected excess. This strategy is applied to search for new high $p_T$ physics in $\\approx$ 100 $pb^{-1}$ of $p\\bar{p}$ collisions at $\\sqrt{s}$ = 1:8 TeV collected by the D0 experiment during 1992{1996 at the Fermilab Tevatron. We systematically analyze many exclusive final states, and demonstrate sensitivity to a variety of models predicting new phenomena at the electroweak scale. No evidence of new high $p_T$ physics is observed.
Energy Technology Data Exchange (ETDEWEB)
Rioual, Michel [Societe Electricite de France (EDF) (France). Themis Dept.; Reveret, Jean-Christophe [Ecole Speciale de Mecanique et d' Electricite, Ivry-sur-Seine (France)
2009-07-01
The energization of the main transformers for wind-farms is an important issue, as it has a major impact on the voltage dips at the Delivery Point and consequently on the power delivery. One of the main point is the determination of the phenomena at the transformer energizing prior its energization, which are described in the paper, and mainly the residual fluxes circulating in the iron core. The residual fluxes have been determined in the case of the de-energization of the main transformers for wind-farms, with a detailed modelling of the equipment under the phenomena involved. A methodology is presented to obtain those fluxes; the values obtained have then be considered as initial conditions for the transformers energization, the inrush currents and overvoltages determined by the EMTP-RV program, and finally validated by on site tests. (orig.)
Generomak: Fusion physics, engineering and costing model
International Nuclear Information System (INIS)
Delene, J.G.; Krakowski, R.A.; Sheffield, J.; Dory, R.A.
1988-06-01
A generic fusion physics, engineering and economics model (Generomak) was developed as a means of performing consistent analysis of the economic viability of alternative magnetic fusion reactors. The original Generomak model developed at Oak Ridge by Sheffield was expanded for the analyses of the Senior Committee on Environmental Safety and Economics of Magnetic Fusion Energy (ESECOM). This report describes the Generomak code as used by ESECOM. The input data used for each of the ten ESECOM fusion plants and the Generomak code output for each case is given. 14 refs., 3 figs., 17 tabs
Wind Tunnel Test of a Risk-Reduction Wing/Fuselage Model to Examine Juncture-Flow Phenomena
Kegerise, Michael A.; Neuhart, Dan H.
2016-01-01
A wing/fuselage wind-tunnel model was tested in the Langley 14- by 22-foot Subsonic Wind Tunnel in preparation for a highly-instrumented Juncture Flow Experiment to be conducted in the same facility. This test, which was sponsored by the NASA Transformational Tool and Technologies Project, is part of a comprehensive set of experimental and computational research activities to develop revolutionary, physics-based aeronautics analysis and design capability. The objectives of this particular test were to examine the surface and off-body flow on a generic wing/body combination to: 1) choose a final wing for a future, highly instrumented model, 2) use the results to facilitate unsteady pressure sensor placement on the model, 3) determine the area to be surveyed with an embedded laser-doppler velocimetry (LDV) system, 4) investigate the primary juncture corner- flow separation region using particle image velocimetry (PIV) to see if the particle seeding is adequately entrained and to examine the structure in the separated region, and 5) to determine the similarity of observed flow features with those predicted by computational fluid dynamics (CFD). This report documents the results of the above experiment that specifically address the first three goals. Multiple wing configurations were tested at a chord Reynolds number of 2.4 million. Flow patterns on the surface of the wings and in the region of the wing/fuselage juncture were examined using oil- flow visualization and infrared thermography. A limited number of unsteady pressure sensors on the fuselage around the wing leading and trailing edges were used to identify any dynamic effects of the horseshoe vortex on the flow field. The area of separated flow in the wing/fuselage juncture near the wing trailing edge was observed for all wing configurations at various angles of attack. All of the test objectives were met. The staff of the 14- by 22-foot Subsonic Wind Tunnel provided outstanding support and delivered
Physics based modeling and control of reactive extrusion
Elkouss, Paul F.
2004-11-01
Kinematic modeling has been shown to be important for the understanding and control of co-rotating twin screw extruders. The residence time distribution (RTD) is often used to characterize the steady-state behavior of an extrusion process. Due to the complex rheological behavior of polymer flow in the extruder, few have felt that the RTD would be independent of changes in operating conditions for the same screw configuration. To investigate, we are asserting that resident distributions could be independent of operating conditions for certain types of polymers. Four different polymers, two polyethylenes and two polypropylenes, were processed on the same 30mm Werner and Pfleiderer co-rotating twin-screw extruder (CoTSE) equipped with reflectance optical probes to compare their RTD's. Additionally, each material was tested to determine its complex viscosity, to better understand the phenomena involved. Using physically motivated models to control reactive extrusion processes is attractive because of the flexibility and robustness it could provide. This thesis uses residence distribution analyses to characterize the material flow through a co-rotating twin-screw extruder. Furthermore, we examine the applicability of residence distributions as the basis for kinematic modeling of the extrusion process. This demonstration of using a steady-state model---the residence distribution---as a basis for kinematic behavior is unique. The signals have been deconvoluted to kinematically characterize the flow in the different regions of the extruder, such as the melting, mixing and metering zones. Studies of step changes have shown that the steady state value of extrudate viscosity is dependent on the peroxide concentration, volume mixing, and on the residence time from the specific throughput. This data has also provided plant models of the peroxide initiated degradation reaction using system identification techniques. Although a specific example of vis-breaking of polypropylene is
Slush Fund: Modeling the Multiphase Physics of Oceanic Ices
Buffo, J.; Schmidt, B. E.
2016-12-01
The prevalence of ice interacting with an ocean, both on Earth and throughout the solar system, and its crucial role as the mediator of exchange between the hydrosphere below and atmosphere above, have made quantifying the thermodynamic, chemical, and physical properties of the ice highly desirable. While direct observations of these quantities exist, their scarcity increases with the difficulty of obtainment; the basal surfaces of terrestrial ice shelves remain largely unexplored and the icy interiors of moons like Europa and Enceladus have never been directly observed. Our understanding of these entities thus relies on numerical simulation, and the efficacy of their incorporation into larger systems models is dependent on the accuracy of these initial simulations. One characteristic of seawater, likely shared by the oceans of icy moons, is that it is a solution. As such, when it is frozen a majority of the solute is rejected from the forming ice, concentrating in interstitial pockets and channels, producing a two-component reactive porous media known as a mushy layer. The multiphase nature of this layer affects the evolution and dynamics of the overlying ice mass. Additionally ice can form in the water column and accrete onto the basal surface of these ice masses via buoyancy driven sedimentation as frazil or platelet ice. Numerical models hoping to accurately represent ice-ocean interactions should include the multiphase behavior of these two phenomena. While models of sea ice have begun to incorporate multiphase physics into their capabilities, no models of ice shelves/shells explicitly account for the two-phase behavior of the ice-ocean interface. Here we present a 1D multiphase model of floating oceanic ice that includes parameterizations of both density driven advection within the `mushy layer' and buoyancy driven sedimentation. The model is validated against contemporary sea ice models and observational data. Environmental stresses such as supercooling and
Workshop on Interface Phenomena
Kreuzer, Hans
1987-01-01
This book contains the proceedings of the first Workshop on Interface Phenomena, organized jointly by the surface science groups at Dalhousie University and the University of Maine. It was our intention to concentrate on just three topics related to the kinetics of interface reactions which, in our opinion, were frequently obscured unnecessarily in the literature and whose fundamental nature warranted an extensive discussion to help clarify the issues, very much in the spirit of the Discussions of the Faraday Society. Each session (day) saw two principal speakers expounding the different views; the session chairmen were asked to summarize the ensuing discussions. To understand the complexity of interface reactions, paradigms must be formulated to provide a framework for the interpretation of experimen tal data and for the construction of theoretical models. Phenomenological approaches have been based on a small number of rate equations for the concentrations or mole numbers of the various species involved i...
The theory of critical phenomena in two-dimensional systems
International Nuclear Information System (INIS)
Olvera de la C, M.
1981-01-01
An exposition of the theory of critical phenomena in two-dimensional physical systems is presented. The first six chapters deal with the mean field theory of critical phenomena, scale invariance of the thermodynamic functions, Kadanoff's spin block construction, Wilson's renormalization group treatment of critical phenomena in configuration space, and the two-dimensional Ising model on a triangular lattice. The second part of this work is made of four chapters devoted to the application of the ideas expounded in the first part to the discussion of critical phenomena in superfluid films, two-dimensional crystals and the two-dimensional XY model of magnetic systems. Chapters seven to ten are devoted to the following subjects: analysis of long range order in one, two, and three-dimensional physical systems. Topological defects in the XY model, in superfluid films and in two-dimensional crystals. The Thouless-Kosterlitz iterated mean field theory of the dipole gas. The renormalization group treatment of the XY model, superfluid films and two-dimensional crystal. (author)
International Nuclear Information System (INIS)
Nagai, Haruyasu; Yamazawa, Hiromi
1997-01-01
It is advantageous for an emergency response system to have a forecast function to provide a time margin for countermeasures in case of a nuclear accident. We propose to apply an atmospheric dynamic model PHYSIC (Prognostic HYdroStatic model Including turbulence Closure model) as a meteorological forecast model in the emergency system. The model uses GPV data which are the output of the numerical weather forecast model of Japan Meteorological Agency as the initial and boundary conditions. The roles of PHYSIC are the interface between GPV data and the emergency response system and the forecast of local atmospheric phenomena within the model domain. This paper presents a scheme to use PHYSIC to forecast local wind and its performance. Horizontal grid number of PHYSIC is fixed to 50 x 50, whereas the mesh and domain sizes are determined in consideration of topography causing local winds at an objective area. The model performance was examined for the introduction of GPV data through initial and boundary conditions and the predictability of local wind field and atmospheric stability. The model performance was on an acceptable level as the forecast model. It was also recognized that improvement of cloud calculation was necessary in simulating atmospheric stability. (author)
Physical vs. Mathematical Models in Rock Mechanics
Morozov, I. B.; Deng, W.
2013-12-01
One of the less noted challenges in understanding the mechanical behavior of rocks at both in situ and lab conditions is the character of theoretical approaches being used. Currently, the emphasis is made on spatial averaging theories (homogenization and numerical models of microstructure), empirical models for temporal behavior (material memory, compliance functions and complex moduli), and mathematical transforms (Laplace and Fourier) used to infer the Q-factors and 'relaxation mechanisms'. In geophysical applications, we have to rely on such approaches for very broad spatial and temporal scales which are not available in experiments. However, the above models often make insufficient use of physics and utilize, for example, the simplified 'correspondence principle' instead of the laws of viscosity and friction. As a result, the commonly-used time- and frequency dependent (visco)elastic moduli represent apparent properties related to the measurement procedures and not necessarily to material properties. Predictions made from such models may therefore be inaccurate or incorrect when extrapolated beyond the lab scales. To overcome the above challenge, we need to utilize the methods of micro- and macroscopic mechanics and thermodynamics known in theoretical physics. This description is rigorous and accurate, uses only partial differential equations, and allows straightforward numerical implementations. One important observation from the physical approach is that the analysis should always be done for the specific geometry and parameters of the experiment. Here, we illustrate these methods on axial deformations of a cylindrical rock sample in the lab. A uniform, isotropic elastic rock with a thermoelastic effect is considered in four types of experiments: 1) axial extension with free transverse boundary, 2) pure axial extension with constrained transverse boundary, 3) pure bulk expansion, and 4) axial loading harmonically varying with time. In each of these cases, an
Fast Particle Methods for Multiscale Phenomena Simulations
Koumoutsakos, P.; Wray, A.; Shariff, K.; Pohorille, Andrew
2000-01-01
We are developing particle methods oriented at improving computational modeling capabilities of multiscale physical phenomena in : (i) high Reynolds number unsteady vortical flows, (ii) particle laden and interfacial flows, (iii)molecular dynamics studies of nanoscale droplets and studies of the structure, functions, and evolution of the earliest living cell. The unifying computational approach involves particle methods implemented in parallel computer architectures. The inherent adaptivity, robustness and efficiency of particle methods makes them a multidisciplinary computational tool capable of bridging the gap of micro-scale and continuum flow simulations. Using efficient tree data structures, multipole expansion algorithms, and improved particle-grid interpolation, particle methods allow for simulations using millions of computational elements, making possible the resolution of a wide range of length and time scales of these important physical phenomena.The current challenges in these simulations are in : [i] the proper formulation of particle methods in the molecular and continuous level for the discretization of the governing equations [ii] the resolution of the wide range of time and length scales governing the phenomena under investigation. [iii] the minimization of numerical artifacts that may interfere with the physics of the systems under consideration. [iv] the parallelization of processes such as tree traversal and grid-particle interpolations We are conducting simulations using vortex methods, molecular dynamics and smooth particle hydrodynamics, exploiting their unifying concepts such as : the solution of the N-body problem in parallel computers, highly accurate particle-particle and grid-particle interpolations, parallel FFT's and the formulation of processes such as diffusion in the context of particle methods. This approach enables us to transcend among seemingly unrelated areas of research.
Recent results of searches for beyond Standard Model physics in ATLAS
Serkin, Leonid; The ATLAS collaboration
2017-01-01
Recent results of searches for beyond Standard Model physics in ATLAS are presented, with particular focus on searches for new phenomena in high jet multiplicity final states. These include searches for charged Higgs boson in the $H^{+} \\to tb $ decay channel, vector-like quark pair production, four-top-quark production in different signal benchmark scenarios and associated heavy Higgs boson production. No significant excess are observed in data and exclusion limits on cross sections and masses are given for the signal models in a number of benchmark scenarios, in most cases significantly extending the reach of previous searches.
Physics Beyond the Standard Model: Supersymmetry
Energy Technology Data Exchange (ETDEWEB)
Nojiri, M.M.; /KEK, Tsukuba /Tsukuba, Graduate U. Adv. Studies /Tokyo U.; Plehn, T.; /Edinburgh U.; Polesello, G.; /INFN, Pavia; Alexander, John M.; /Edinburgh U.; Allanach, B.C.; /Cambridge U.; Barr, Alan J.; /Oxford U.; Benakli, K.; /Paris U., VI-VII; Boudjema, F.; /Annecy, LAPTH; Freitas, A.; /Zurich U.; Gwenlan, C.; /University Coll. London; Jager, S.; /CERN /LPSC, Grenoble
2008-02-01
This collection of studies on new physics at the LHC constitutes the report of the supersymmetry working group at the Workshop 'Physics at TeV Colliders', Les Houches, France, 2007. They cover the wide spectrum of phenomenology in the LHC era, from alternative models and signatures to the extraction of relevant observables, the study of the MSSM parameter space and finally to the interplay of LHC observations with additional data expected on a similar time scale. The special feature of this collection is that while not each of the studies is explicitly performed together by theoretical and experimental LHC physicists, all of them were inspired by and discussed in this particular environment.
Physical model for membrane protrusions during spreading
International Nuclear Information System (INIS)
Chamaraux, F; Ali, O; Fourcade, B; Keller, S; Bruckert, F
2008-01-01
During cell spreading onto a substrate, the kinetics of the contact area is an observable quantity. This paper is concerned with a physical approach to modeling this process in the case of ameboid motility where the membrane detaches itself from the underlying cytoskeleton at the leading edge. The physical model we propose is based on previous reports which highlight that membrane tension regulates cell spreading. Using a phenomenological feedback loop to mimic stress-dependent biochemistry, we show that the actin polymerization rate can be coupled to the stress which builds up at the margin of the contact area between the cell and the substrate. In the limit of small variation of membrane tension, we show that the actin polymerization rate can be written in a closed form. Our analysis defines characteristic lengths which depend on elastic properties of the membrane–cytoskeleton complex, such as the membrane–cytoskeleton interaction, and on molecular parameters, the rate of actin polymerization. We discuss our model in the case of axi-symmetric and non-axi-symmetric spreading and we compute the characteristic time scales as a function of fundamental elastic constants such as the strength of membrane–cytoskeleton adherence
Physical Model Development and Benchmarking for MHD Flows in Blanket Design
Energy Technology Data Exchange (ETDEWEB)
Ramakanth Munipalli; P.-Y.Huang; C.Chandler; C.Rowell; M.-J.Ni; N.Morley; S.Smolentsev; M.Abdou
2008-06-05
An advanced simulation environment to model incompressible MHD flows relevant to blanket conditions in fusion reactors has been developed at HyPerComp in research collaboration with TEXCEL. The goals of this phase-II project are two-fold: The first is the incorporation of crucial physical phenomena such as induced magnetic field modeling, and extending the capabilities beyond fluid flow prediction to model heat transfer with natural convection and mass transfer including tritium transport and permeation. The second is the design of a sequence of benchmark tests to establish code competence for several classes of physical phenomena in isolation as well as in select (termed here as “canonical”,) combinations. No previous attempts to develop such a comprehensive MHD modeling capability exist in the literature, and this study represents essentially uncharted territory. During the course of this Phase-II project, a significant breakthrough was achieved in modeling liquid metal flows at high Hartmann numbers. We developed a unique mathematical technique to accurately compute the fluid flow in complex geometries at extremely high Hartmann numbers (10,000 and greater), thus extending the state of the art of liquid metal MHD modeling relevant to fusion reactors at the present time. These developments have been published in noted international journals. A sequence of theoretical and experimental results was used to verify and validate the results obtained. The code was applied to a complete DCLL module simulation study with promising results.
Physical Model Development and Benchmarking for MHD Flows in Blanket Design
International Nuclear Information System (INIS)
Munipalli, Ramakanth; Huang, P.-Y.; Chandler, C.; Rowell, C.; Ni, M.-J.; Morley, N.; Smolentsev, S.; Abdou, M.
2008-01-01
An advanced simulation environment to model incompressible MHD flows relevant to blanket conditions in fusion reactors has been developed at HyPerComp in research collaboration with TEXCEL. The goals of this phase-II project are two-fold: The first is the incorporation of crucial physical phenomena such as induced magnetic field modeling, and extending the capabilities beyond fluid flow prediction to model heat transfer with natural convection and mass transfer including tritium transport and permeation. The second is the design of a sequence of benchmark tests to establish code competence for several classes of physical phenomena in isolation as well as in select (termed here as 'canonical',) combinations. No previous attempts to develop such a comprehensive MHD modeling capability exist in the literature, and this study represents essentially uncharted territory. During the course of this Phase-II project, a significant breakthrough was achieved in modeling liquid metal flows at high Hartmann numbers. We developed a unique mathematical technique to accurately compute the fluid flow in complex geometries at extremely high Hartmann numbers (10,000 and greater), thus extending the state of the art of liquid metal MHD modeling relevant to fusion reactors at the present time. These developments have been published in noted international journals. A sequence of theoretical and experimental results was used to verify and validate the results obtained. The code was applied to a complete DCLL module simulation study with promising results.
Containment severe accident thermohydraulic phenomena
International Nuclear Information System (INIS)
Frid, W.
1991-08-01
This report describes and discusses the containment accident progression and the important severe accident containment thermohydraulic phenomena. The overall objective of the report is to provide a rather detailed presentation of the present status of phenomenological knowledge, including an account of relevant experimental investigations and to discuss, to some extent, the modelling approach used in the MAAP 3.0 computer code. The MAAP code has been used in Sweden as the main tool in the analysis of severe accidents. The dependence of the containment accident progression and containment phenomena on the initial conditions, which in turn are heavily dependent on the in-vessel accident progression and phenomena as well as associated uncertainties, is emphasized. The report is in three parts dealing with: * Swedish reactor containments, the severe accident mitigation programme in Sweden and containment accident progression in Swedish PWRs and BWRs as predicted by the MAAP 3.0 code. * Key non-energetic ex-vessel phenomena (melt fragmentation in water, melt quenching and coolability, core-concrete interaction and high temperature in containment). * Early containment threats due to energetic events (hydrogen combustion, high pressure melt ejection and direct containment heating, and ex-vessel steam explosions). The report concludes that our understanding of the containment severe accident progression and phenomena has improved very significantly over the parts ten years and, thereby, our ability to assess containment threats, to quantify uncertainties, and to interpret the results of experiments and computer code calculations have also increased. (au)
Gray, William G; Miller, Cass T
2010-12-01
This work is the eighth in a series that develops the fundamental aspects of the thermodynamically constrained averaging theory (TCAT) that allows for a systematic increase in the scale at which multiphase transport phenomena is modeled in porous medium systems. In these systems, the explicit locations of interfaces between phases and common curves, where three or more interfaces meet, are not considered at scales above the microscale. Rather, the densities of these quantities arise as areas per volume or length per volume. Modeling of the dynamics of these measures is an important challenge for robust models of flow and transport phenomena in porous medium systems, as the extent of these regions can have important implications for mass, momentum, and energy transport between and among phases, and formulation of a capillary pressure relation with minimal hysteresis. These densities do not exist at the microscale, where the interfaces and common curves correspond to particular locations. Therefore, it is necessary for a well-developed macroscale theory to provide evolution equations that describe the dynamics of interface and common curve densities. Here we point out the challenges and pitfalls in producing such evolution equations, develop a set of such equations based on averaging theorems, and identify the terms that require particular attention in experimental and computational efforts to parameterize the equations. We use the evolution equations developed to specify a closed two-fluid-phase flow model.
Quantum theory of collective phenomena
Sewell, G L
2014-01-01
""An excellent and competent introduction to the field … [and] … a source of information for the expert."" - Physics Today""This a book of major importance…. I trust that this book will be used as a basis for the teaching of a balanced, modern and rigorous course on statistical mechanics in all universities."" - Bulletin of the London Mathematical Society""This is one of the best introductions to the subject, and it is strongly recommended to anyone interested in collective phenomena."" - Physics Bulletin ""The book may be recommended for students as a well-balanced introduction to this rich s
Lavignac, Stephan; Dalibard, Jean
2006-01-01
The Standard Model of elementary particles and interactions is one of the tested theories in physics. This book presents a collection of lectures given in August 2005 at the Les Houches Summer School on Particle Physics beyond the Standard Model. It provides a pedagogical introduction to the aspects of particle physics beyond the Standard Model
Physics-based models of the plasmasphere
Energy Technology Data Exchange (ETDEWEB)
Jordanova, Vania K [Los Alamos National Laboratory; Pierrard, Vivane [BELGIUM; Goldstein, Jerry [SWRI; Andr' e, Nicolas [ESTEC/ESA; Kotova, Galina A [SRI, RUSSIA; Lemaire, Joseph F [BELGIUM; Liemohn, Mike W [U OF MICHIGAN; Matsui, H [UNIV OF NEW HAMPSHIRE
2008-01-01
We describe recent progress in physics-based models of the plasmasphere using the Auid and the kinetic approaches. Global modeling of the dynamics and inAuence of the plasmasphere is presented. Results from global plasmasphere simulations are used to understand and quantify (i) the electric potential pattern and evolution during geomagnetic storms, and (ii) the inAuence of the plasmasphere on the excitation of electromagnetic ion cyclotron (ElvIIC) waves a.nd precipitation of energetic ions in the inner magnetosphere. The interactions of the plasmasphere with the ionosphere a.nd the other regions of the magnetosphere are pointed out. We show the results of simulations for the formation of the plasmapause and discuss the inAuence of plasmaspheric wind and of ultra low frequency (ULF) waves for transport of plasmaspheric material. Theoretical formulations used to model the electric field and plasma distribution in the plasmasphere are given. Model predictions are compared to recent CLUSTER and MAGE observations, but also to results of earlier models and satellite observations.
Relativistic nuclear physics with the spectator model
International Nuclear Information System (INIS)
Gross, F.
1988-01-01
The spectator model, a general approach to the relativistic treatment of nuclear physics problems in which spectators to nuclear interactions are put on their mass-shell, will be defined nd described. The approach grows out of the relativistic treatment of two and three body systems in which one particle is off-shell, and recent numerical results for the NN interaction will be presented. Two meson-exchange models, one with only 4 mesons (π, σ, /rho/, ω) but with a 25% admixture of γ 5 coupling for the pion, and a second with 6 mesons (π, σ, /rho/, ω, δ, and /eta/) but a pure γ 5 γ/sup mu/ pion coupling, are shown to give very good quantitative fits to NN scattering phase shifts below 400 MeV, and also a good description of the /rho/ 40 Cα elastic scattering observables. 19 refs., 6 figs., 1 tab
Physical and Chemical Environmental Abstraction Model
International Nuclear Information System (INIS)
Nowak, E.
2000-01-01
As directed by a written development plan (CRWMS M and O 1999a), Task 1, an overall conceptualization of the physical and chemical environment (P/CE) in the emplacement drift is documented in this Analysis/Model Report (AMR). Included are the physical components of the engineered barrier system (EBS). The intended use of this descriptive conceptualization is to assist the Performance Assessment Department (PAD) in modeling the physical and chemical environment within a repository drift. It is also intended to assist PAD in providing a more integrated and complete in-drift geochemical model abstraction and to answer the key technical issues raised in the U.S. Nuclear Regulatory Commission (NRC) Issue Resolution Status Report (IRSR) for the Evolution of the Near-Field Environment (NFE) Revision 2 (NRC 1999). EBS-related features, events, and processes (FEPs) have been assembled and discussed in ''EBS FEPs/Degradation Modes Abstraction'' (CRWMS M and O 2000a). Reference AMRs listed in Section 6 address FEPs that have not been screened out. This conceptualization does not directly address those FEPs. Additional tasks described in the written development plan are recommended for future work in Section 7.3. To achieve the stated purpose, the scope of this document includes: (1) the role of in-drift physical and chemical environments in the Total System Performance Assessment (TSPA) (Section 6.1); (2) the configuration of engineered components (features) and critical locations in drifts (Sections 6.2.1 and 6.3, portions taken from EBS Radionuclide Transport Abstraction (CRWMS M and O 2000b)); (3) overview and critical locations of processes that can affect P/CE (Section 6.3); (4) couplings and relationships among features and processes in the drifts (Section 6.4); and (5) identities and uses of parameters transmitted to TSPA by some of the reference AMRs (Section 6.5). This AMR originally considered a design with backfill, and is now being updated (REV 00 ICN1) to address
Propulsion Physics Using the Chameleon Density Model
Robertson, Glen A.
2011-01-01
To grow as a space faring race, future spaceflight systems will require a new theory of propulsion. Specifically one that does not require mass ejection without limiting the high thrust necessary to accelerate within or beyond our solar system and return within a normal work period or lifetime. The Chameleon Density Model (CDM) is one such model that could provide new paths in propulsion toward this end. The CDM is based on Chameleon Cosmology a dark matter theory; introduced by Khrouy and Weltman in 2004. Chameleon as it is hidden within known physics, where the Chameleon field represents a scalar field within and about an object; even in the vacuum. The CDM relates to density changes in the Chameleon field, where the density changes are related to matter accelerations within and about an object. These density changes in turn change how an object couples to its environment. Whereby, thrust is achieved by causing a differential in the environmental coupling about an object. As a demonstration to show that the CDM fits within known propulsion physics, this paper uses the model to estimate the thrust from a solid rocket motor. Under the CDM, a solid rocket constitutes a two body system, i.e., the changing density of the rocket and the changing density in the nozzle arising from the accelerated mass. Whereby, the interactions between these systems cause a differential coupling to the local gravity environment of the earth. It is shown that the resulting differential in coupling produces a calculated value for the thrust near equivalent to the conventional thrust model used in Sutton and Ross, Rocket Propulsion Elements. Even though imbedded in the equations are the Universe energy scale factor, the reduced Planck mass and the Planck length, which relates the large Universe scale to the subatomic scale.
International Nuclear Information System (INIS)
Kim, Keun Su; Park, Jin Myung; Choi, Sooseok; Kim, Jongin; Hong, Sang Hee
2008-01-01
A comparative study between two- and three-dimensional (2D and 3D) modeling is carried out on arc discharge phenomena inside a thermal plasma torch with hollow electrodes, in order to evaluate the effects of arc root configuration characterized by either 2D annular or 3D highly localized attachment on the electrode surface. For this purpose, a more precise 3D transient model has been developed by taking account of 3D arc current distribution and arc root rotation. The 3D simulation results apparently reveal that the 3D arc root attachment brings about the inherent 3D and turbulence nature of plasma fields inside the torch. It is also found that the constricted arc column near the vortex chamber plays an important role in heating and acceleration of injected arc gases by concentrating arc currents on the axis of the hollow electrodes. The inherent 3D nature of arc discharge is well preserved inside the cathode region, while these 3D features slowly diminish behind the vortex chamber where the turbulent flow begins to be developed in the anode region. Based on the present simulation results, it is noted that the mixing effects of the strong turbulent flow on the heat and mass transfer are mainly responsible for the gradual relaxation of the 3D structures of plasma fields into the 2D axisymmetric ones that eventually appear in the anode region near the torch exit. From a detailed comparison of the 3D results with the 2D ones, the arc root configuration seems to have a significant effect on the heat transfer to the electrode surfaces interacting with the turbulent plasma flow. That is, in the 2D simulation based on an axisymmetric stationary model, the turbulence phenomena are fairly underestimated and the amount of heat transferred to the cold anode wall is calculated to be smaller than that obtained in the 3D simulation. For the validation of the numerical simulations, calculated plasma temperatures and axial velocities are compared with experimentally measured ones
Remote sensing of natural phenomena
Directory of Open Access Journals (Sweden)
Miodrag D. Regodić
2014-06-01
Full Text Available There has always been a need to directly perceive and study the events whose extent is beyond people's possibilities. In order to get new data and to make observations and studying much more objective in comparison with past syntheses - a new method of examination called remote sensing has been adopted. The paper deals with the principles and elements of remote sensing, as well as with the basic aspects of using remote research in examining meteorological (weather parameters and the conditions of the atmosphere. The usage of satellite images is possible in all phases of the global and systematic research of different natural phenomena when airplane and satellite images of different characteristics are used and their analysis and interpretation is carried out by viewing and computer added procedures. Introduction Remote sensing of the Earth enables observing and studying global and local events that occur on it. Satellite images are nowadays used in geology, agriculture, forestry, geodesy, meteorology, spatial and urbanism planning, designing of infrastructure and other objects, protection from natural and technological catastrophes, etc. It it possible to use satellite images in all phases of global and systematic research of different natural phenomena. Basics of remote sensing Remote sensing is a method of the acquisition and interpretation of information about remote objects without making a physical contact with them. The term Daljinska detekcija is a literal translation of the English term Remote Sensing. In French it isTeledetection, in German - Fernerkundung, in Russian - дистанционие иследования. We also use terms such as: remote survailance, remote research, teledetection, remote methods, and distance research. The basic elements included in Remote Sensing are: object, electromagnetic energy, sensor, platform, image, analysis, interpretation and the information (data, fact. Usage of satellite remote research in
Thermostatted kinetic equations as models for complex systems in physics and life sciences.
Bianca, Carlo
2012-12-01
Statistical mechanics is a powerful method for understanding equilibrium thermodynamics. An equivalent theoretical framework for nonequilibrium systems has remained elusive. The thermodynamic forces driving the system away from equilibrium introduce energy that must be dissipated if nonequilibrium steady states are to be obtained. Historically, further terms were introduced, collectively called a thermostat, whose original application was to generate constant-temperature equilibrium ensembles. This review surveys kinetic models coupled with time-reversible deterministic thermostats for the modeling of large systems composed both by inert matter particles and living entities. The introduction of deterministic thermostats allows to model the onset of nonequilibrium stationary states that are typical of most real-world complex systems. The first part of the paper is focused on a general presentation of the main physical and mathematical definitions and tools: nonequilibrium phenomena, Gauss least constraint principle and Gaussian thermostats. The second part provides a review of a variety of thermostatted mathematical models in physics and life sciences, including Kac, Boltzmann, Jager-Segel and the thermostatted (continuous and discrete) kinetic for active particles models. Applications refer to semiconductor devices, nanosciences, biological phenomena, vehicular traffic, social and economics systems, crowds and swarms dynamics. Copyright © 2012 Elsevier B.V. All rights reserved.
Fuzzy modelling of Atlantic salmon physical habitat
St-Hilaire, André; Mocq, Julien; Cunjak, Richard
2015-04-01
Fish habitat models typically attempt to quantify the amount of available river habitat for a given fish species for various flow and hydraulic conditions. To achieve this, information on the preferred range of values of key physical habitat variables (e.g. water level, velocity, substrate diameter) for the targeted fishs pecies need to be modelled. In this context, we developed several habitat suitability indices sets for three Atlantic salmon life stages (young-of-the-year (YOY), parr, spawning adults) with the help of fuzzy logic modeling. Using the knowledge of twenty-seven experts, from both sides of the Atlantic Ocean, we defined fuzzy sets of four variables (depth, substrate size, velocity and Habitat Suitability Index, or HSI) and associated fuzzy rules. When applied to the Romaine River (Canada), median curves of standardized Weighted Usable Area (WUA) were calculated and a confidence interval was obtained by bootstrap resampling. Despite the large range of WUA covered by the expert WUA curves, confidence intervals were relatively narrow: an average width of 0.095 (on a scale of 0 to 1) for spawning habitat, 0.155 for parr rearing habitat and 0.160 for YOY rearing habitat. When considering an environmental flow value corresponding to 90% of the maximum reached by WUA curve, results seem acceptable for the Romaine River. Generally, this proposed fuzzy logic method seems suitable to model habitat availability for the three life stages, while also providing an estimate of uncertainty in salmon preferences.
Computer Integrated Manufacturing: Physical Modelling Systems Design. A Personal View.
Baker, Richard
A computer-integrated manufacturing (CIM) Physical Modeling Systems Design project was undertaken in a time of rapid change in the industrial, business, technological, training, and educational areas in Australia. A specification of a manufacturing physical modeling system was drawn up. Physical modeling provides a flexibility and configurability…
In vessel core melt progression phenomena
International Nuclear Information System (INIS)
Courtaud, M.
1993-01-01
For all light water reactor (LWR) accidents, including the so called severe accidents where core melt down can occur, it is necessary to determine the amount and characteristics of fission products released to the environment. For existing reactors this knowledge is used to evaluate the consequences and eventual emergency plans. But for future reactors safety authorities demand decrease risks and reactors designed in such a way that fission products are retained inside the containment, the last protective barrier. This requires improved understanding and knowledge of all accident sequences. In particular it is necessary to be able to describe the very complex phenomena occurring during in vessel core melt progression because they will determine the thermal and mechanical loads on the primary circuit and the timing of its rupture as well as the fission product source term. On the other hand, in case of vessel failure, knowledge of the physical and chemical state of the core melt will provide the initial conditions for analysis of ex-vessel core melt progression and phenomena threatening the containment. Finally a good understanding of in vessel phenomena will help to improve accident management procedures like Emergency Core Cooling System water injection, blowdown and flooding of the vessel well, with their possible adverse effects. Research and Development work on this subject was initiated a long time ago and is still in progress but now it must be intensified in order to meet the safety requirements of the next generation of reactors. Experiments, limited in scale, analysis of the TMI 2 accident which is a unique source of global information and engineering judgment are used to establish and assess physical models that can be implemented in computer codes for reactor accident analysis
Maxwell Prize Talk: Scaling Laws for the Dynamical Plasma Phenomena
Ryutov, Livermore, Ca 94550, Usa, D. D.
2017-10-01
The scaling and similarity technique is a powerful tool for developing and testing reduced models of complex phenomena, including plasma phenomena. The technique has been successfully used in identifying appropriate simplified models of transport in quasistationary plasmas. In this talk, the similarity and scaling arguments will be applied to highly dynamical systems, in which temporal evolution of the plasma leads to a significant change of plasma dimensions, shapes, densities, and other parameters with respect to initial state. The scaling and similarity techniques for dynamical plasma systems will be presented as a set of case studies of problems from various domains of the plasma physics, beginning with collisonless plasmas, through intermediate collisionalities, to highly collisional plasmas describable by the single-fluid MHD. Basic concepts of the similarity theory will be introduced along the way. Among the results discussed are: self-similarity of Langmuir turbulence driven by a hot electron cloud expanding into a cold background plasma; generation of particle beams in disrupting pinches; interference between collisionless and collisional phenomena in the shock physics; similarity for liner-imploded plasmas; MHD similarities with an emphasis on the effect of small-scale (turbulent) structures on global dynamics. Relations between astrophysical phenomena and scaled laboratory experiments will be discussed.
Ultrashort Laser Pulse Phenomena
Diels, Jean-Claude
2006-01-01
Ultrashort Laser Pulse Phenomena, 2e serves as an introduction to the phenomena of ultra short laser pulses and describes how this technology can be used to examine problems in areas such as electromagnetism, optics, and quantum mechanics. Ultrashort Laser Pulse Phenomena combines theoretical backgrounds and experimental techniques and will serve as a manual on designing and constructing femtosecond (""faster than electronics"") systems or experiments from scratch. Beyond the simple optical system, the various sources of ultrashort pulses are presented, again with emphasis on the basic
Outstanding questions: physics beyond the Standard Model
Ellis, John
2012-01-01
The Standard Model of particle physics agrees very well with experiment, but many important questions remain unanswered, among them are the following. What is the origin of particle masses and are they due to a Higgs boson? How does one understand the number of species of matter particles and how do they mix? What is the origin of the difference between matter and antimatter, and is it related to the origin of the matter in the Universe? What is the nature of the astrophysical dark matter? How does one unify the fundamental interactions? How does one quantize gravity? In this article, I introduce these questions and discuss how they may be addressed by experiments at the Large Hadron Collider, with particular attention to the search for the Higgs boson and supersymmetry.
Physical Model of Cellular Symmetry Breaking
van der Gucht, Jasper; Sykes, Cécile
2009-01-01
Cells can polarize in response to external signals, such as chemical gradients, cell–cell contacts, and electromagnetic fields. However, cells can also polarize in the absence of an external cue. For example, a motile cell, which initially has a more or less round shape, can lose its symmetry spontaneously even in a homogeneous environment and start moving in random directions. One of the principal determinants of cell polarity is the cortical actin network that underlies the plasma membrane. Tension in this network generated by myosin motors can be relaxed by rupture of the shell, leading to polarization. In this article, we discuss how simplified model systems can help us to understand the physics that underlie the mechanics of symmetry breaking. PMID:20066077
Mathematical models of physics problems (physics research and technology)
Anchordoqui, Luis Alfredo
2013-01-01
This textbook is intended to provide a foundation for a one-semester introductory course on the advanced mathematical methods that form the cornerstones of the hard sciences and engineering. The work is suitable for first year graduate or advanced undergraduate students in the fields of Physics, Astronomy and Engineering. This text therefore employs a condensed narrative sufficient to prepare graduate and advanced undergraduate students for the level of mathematics expected in more advanced graduate physics courses, without too much exposition on related but non-essential material. In contrast to the two semesters traditionally devoted to mathematical methods for physicists, the material in this book has been quite distilled, making it a suitable guide for a one-semester course. The assumption is that the student, once versed in the fundamentals, can master more esoteric aspects of these topics on his or her own if and when the need arises during the course of conducting research. The book focuses on two cor...
Interfacial transport phenomena
Slattery, John C; Oh, Eun-Suok
2007-01-01
Revised and updated extensively from the previous editionDiscusses transport phenomena at common lines or three-phase lines of contactProvides a comprehensive summary about the extensions of continuum mechanics to the nanoscale.
Physics of human cooperation: experimental evidence and theoretical models
Sánchez, Angel
2018-02-01
In recent years, many physicists have used evolutionary game theory combined with a complex systems perspective in an attempt to understand social phenomena and challenges. Prominent among such phenomena is the issue of the emergence and sustainability of cooperation in a networked world of selfish or self-focused individuals. The vast majority of research done by physicists on these questions is theoretical, and is almost always posed in terms of agent-based models. Unfortunately, more often than not such models ignore a number of facts that are well established experimentally, and are thus rendered irrelevant to actual social applications. I here summarize some of the facts that any realistic model should incorporate and take into account, discuss important aspects underlying the relation between theory and experiments, and discuss future directions for research based on the available experimental knowledge.
International Nuclear Information System (INIS)
Jokiniemi, J.; Kilpi, K.; Lindholm, I.; Maekynen, J.; Pekkarinen, E.; Sairanen, R.; Silde, A.
1995-02-01
Severe accidents are nuclear reactor accidents in which the reactor core is substantially damaged. The report describes severe reactor accident phenomena and their significance for the safety of nuclear power plants. A comprehensive set of phenomena ranging from accident initiation to containment behaviour and containment integrity questions are covered. The report is based on expertise gained in the severe accident assessment projects conducted at the Technical Research Centre of Finland (VTT). (49 refs., 32 figs., 12 tabs.)
Integration phenomena Paralympic cyclists
Diepoldová, Tereza
2017-01-01
Title: Integration phenomena Paralympic cyclists. Objectives of work: Try to find integration phenomena in relation to sport training and its impact on selected cyclists with disabilities. Methods: Case report structured interview, data collection method - the method of interrogation. Results: Based on case studies developed a structured interview, we found differences in the integration, which we have divided into phases - before obtaining disability, acclimatization, sports integration. Fur...
Physical Model Method for Seismic Study of Concrete Dams
Directory of Open Access Journals (Sweden)
Bogdan Roşca
2008-01-01
Full Text Available The study of the dynamic behaviour of concrete dams by means of the physical model method is very useful to understand the failure mechanism of these structures to action of the strong earthquakes. Physical model method consists in two main processes. Firstly, a study model must be designed by a physical modeling process using the dynamic modeling theory. The result is a equations system of dimensioning the physical model. After the construction and instrumentation of the scale physical model a structural analysis based on experimental means is performed. The experimental results are gathered and are available to be analysed. Depending on the aim of the research may be designed an elastic or a failure physical model. The requirements for the elastic model construction are easier to accomplish in contrast with those required for a failure model, but the obtained results provide narrow information. In order to study the behaviour of concrete dams to strong seismic action is required the employment of failure physical models able to simulate accurately the possible opening of joint, sliding between concrete blocks and the cracking of concrete. The design relations for both elastic and failure physical models are based on dimensional analysis and consist of similitude relations among the physical quantities involved in the phenomenon. The using of physical models of great or medium dimensions as well as its instrumentation creates great advantages, but this operation involves a large amount of financial, logistic and time resources.
2010-11-21
Methods in Geomechanics 33 pp 1737-1768. Tordesillas, A, Shi, J and Muhlhaus, H (2009) “Non-coaxiality and force chain evolution” International...Buckling force chains in dense granular assemblies: physical and numerical experiments” Geomechanics and Geoengineering 4(1) pp 3-16. Tordesillas, A...J, Tshaikiwsky, T (2010) “Stress-dilatancy and force chain evolution”, International Journal of Numerical and Analytical Methods in Geomechanics DOI
Study of Λ parameters and crossover phenomena in SU(N) x SU(N) sigma models in two dimensions
International Nuclear Information System (INIS)
Shigemitsu, J.; Kogut, J.B.
1981-01-01
The spin system analogues of recent studies of the string tension and Λ parameters of SU(N) gauge theories in 4 dimensions are carried out for the SU(N) x SU(N) and O(N) models in 2 dimensions. The relations between the Λ parameters of both the Euclidean and Hamiltonian formulation of the lattice models and the Λ parameter of the continuum models are obtained. The one loop finite renormalization of the speed of light in the lattice Hamiltonian formulations of the O(N) and SU(N) x SU(N) models is calculated. Strong coupling calculations of the mass gaps of these spin models are done for all N and the constants of proportionality between the gap and the Λ parameter of the continuum models are obtained. These results are contrasted with similar calculations for the SU(N) gauge models in 3+1 dimensions. Identifying suitable coupling constants for discussing the N → infinity limits, the numerical results suggest that the crossover from weak to strong coupling in the lattice O(N) models becomes less abrupt as N increases while the crossover for the SU(N) x SU(N) models becomes more abrupt. The crossover in SU(N) gauge theories also becomes more abrupt with increasing N, however, at an even greater rate than in the SU(N) x SU(N) spin models
Model Unspecific Search for New Physics with High pT Photons in CMS
Schmitz, Stefan Antonius
2009-01-01
In 2009 the LHC collider at the European center of particle physics CERN will start operations, colliding protons with a center of mass energy of up to 14 TeV. Designed as a large multi purpose detector CMS 3 will then start taking collision data. CMS will perform precision measurements within the Standard Model of particle physics and expand the search for new physical phenomena into regions that have not yet been probed by previous experiments. Many theories about what physics beyond the Standard Model at the TeV scale might look like have been proposed. Together these models leave room for a broad spectrum of possible experimental signatures that one might look for in the data. Various analyses focus on processing the available information with the aim of finding evidence for a specific model of choice. MUSiC as a Model Unspecific Search in CMS provides a complementary approach by scanning the data for noteworthy deviations from the Standard Model expectation while making only basic assumptions about the n...
A unified dislocation density-dependent physical-based constitutive model for cold metal forming
Schacht, K.; Motaman, A. H.; Prahl, U.; Bleck, W.
2017-10-01
Dislocation-density-dependent physical-based constitutive models of metal plasticity while are computationally efficient and history-dependent, can accurately account for varying process parameters such as strain, strain rate and temperature; different loading modes such as continuous deformation, creep and relaxation; microscopic metallurgical processes; and varying chemical composition within an alloy family. Since these models are founded on essential phenomena dominating the deformation, they have a larger range of usability and validity. Also, they are suitable for manufacturing chain simulations since they can efficiently compute the cumulative effect of the various manufacturing processes by following the material state through the entire manufacturing chain and also interpass periods and give a realistic prediction of the material behavior and final product properties. In the physical-based constitutive model of cold metal plasticity introduced in this study, physical processes influencing cold and warm plastic deformation in polycrystalline metals are described using physical/metallurgical internal variables such as dislocation density and effective grain size. The evolution of these internal variables are calculated using adequate equations that describe the physical processes dominating the material behavior during cold plastic deformation. For validation, the model is numerically implemented in general implicit isotropic elasto-viscoplasticity algorithm as a user-defined material subroutine (UMAT) in ABAQUS/Standard and used for finite element simulation of upsetting tests and a complete cold forging cycle of case hardenable MnCr steel family.
A Conceptual Model of Observed Physical Literacy
Dudley, Dean A.
2015-01-01
Physical literacy is a concept that is gaining greater acceptance around the world with the United Nations Educational, Cultural, and Scientific Organization (2013) recognizing it as one of several central tenets in a quality physical education framework. However, previous attempts to understand progression in physical literacy learning have been…
International Nuclear Information System (INIS)
Reyes, J.N. Jr.; Cleveland, J.; Aksan, N.
2004-01-01
The International Atomic Energy Agency (IAEA) has established a Coordinated Research Project (CRP) titled ''Natural Circulation Phenomena, Modelling and Reliability of Passive Safety Systems that Utilize Natural Circulation. '' This work has been organized within the framework of the IAEA Department of Nuclear Energy's Technical Working Groups for Advanced Technologies for Light Water Reactors and Heavy Water Reactors (the TWG-LWR and the TWG-HWR). This CRP is part of IAEA's effort to foster international collaborations that strive to improve the economic performance of future water-cooled nuclear power plants while meeting stringent safety requirements. Thus far, IAEA has established 12 research agreements with organizations from industrialized Member States and 3 research contracts with organizations from developing Member States. The objective of the CRP is to enhance our understanding of natural circulation phenomena in water-cooled reactors and passive safety systems. The CRP participants are particularly interested in establishing a natural circulation and passive safety system thermal hydraulic database that can be used to benchmark computer codes for advanced reactor systems design and safety analysis. An important aspect of this CRP relates to developing methodologies to assess the reliability of passive safety systems in advanced reactor designs. This paper describes the motivation and objectives of the CRP, the research plan, and the role of each of the participating organizations. (author)
A Structural Equation Model of Conceptual Change in Physics
Taasoobshirazi, Gita; Sinatra, Gale M.
2011-01-01
A model of conceptual change in physics was tested on introductory-level, college physics students. Structural equation modeling was used to test hypothesized relationships among variables linked to conceptual change in physics including an approach goal orientation, need for cognition, motivation, and course grade. Conceptual change in physics…
A Structural Equation Model of Expertise in College Physics
Taasoobshirazi, Gita; Carr, Martha
2009-01-01
A model of expertise in physics was tested on a sample of 374 college students in 2 different level physics courses. Structural equation modeling was used to test hypothesized relationships among variables linked to expert performance in physics including strategy use, pictorial representation, categorization skills, and motivation, and these…
Models Based Practices in Physical Education: A Sociocritical Reflection
Landi, Dillon; Fitzpatrick, Katie; McGlashan, Hayley
2016-01-01
In this paper, we reflect on models-based practices in physical education using a sociocritical lens. Drawing links between neoliberal moves in education, and critical approaches to the body and physicality, we take a view that models are useful tools that are worth integrating into physical education, but we are apprehensive to suggest they…
The Role of Various Curriculum Models on Physical Activity Levels
Culpepper, Dean O.; Tarr, Susan J.; Killion, Lorraine E.
2011-01-01
Researchers have suggested that physical education curricula can be highly effective in increasing physical activity levels at school (Sallis & Owen, 1999). The purpose of this study was to investigate the impact of various curriculum models on physical activity. Total steps were measured on 1,111 subjects and three curriculum models were studied…
Computational transport phenomena for engineering analyses
Farmer, Richard C; Cheng, Gary C; Chen, Yen-Sen
2009-01-01
Computational Transport PhenomenaOverviewTransport PhenomenaAnalyzing Transport PhenomenaA Computational Tool: The CTP CodeVerification, Validation, and GeneralizationSummaryNomenclatureReferencesThe Equations of ChangeIntroductionDerivation of The Continuity EquationDerivation of The Species Continuity EquationDerivation of The Equation Of MotionDerivation of The General Energy EquationNon-Newtonian FluidsGeneral Property BalanceAnalytical and Approximate Solutions for the Equations of ChangeSummaryNomenclatureReferencesPhysical PropertiesOverviewReal-Fluid ThermodynamicsChemical Equilibrium
Sixteenth International Conference on Ultrafast Phenomena
Corkum, Paul; Nelson, Keith A; Riedle, Eberhard; Schoenlein, Robert W; Ultrafast Phenomena XVI
2009-01-01
Ultrafast Phenomena XVI presents the latest advances in ultrafast science, including both ultrafast optical technology and the study of ultrafast phenomena. It covers picosecond, femtosecond and attosecond processes relevant to applications in physics, chemistry, biology, and engineering. Ultrafast technology has a profound impact in a wide range of applications, amongst them biomedical imaging, chemical dynamics, frequency standards, material processing, and ultrahigh speed communications. This book summarizes the results presented at the 16th International Conference on Ultrafast Phenomena and provides an up-to-date view of this important and rapidly advancing field.
Multi-physics modeling and numerical simulation of weld pool in GTA welding
International Nuclear Information System (INIS)
Nguyen, Minh-Chien
2015-01-01
In this work, we develop a 3D physical and numerical model of the GTA (Gas Tungsten Arc) welding process in order to predict, for given welding parameters, useful quantities for the designer of welded assembly: weld bead shape, fluid flow in the weld pool as well as thermal distribution in the work piece. The model is developed in the Cast3M (http://www-cast3m.cea.fr/) finite element software and takes into account the main physical phenomena acting in the work piece and particularly in the weld pool, subject to source terms modeling the arc part of the welding process. A steady solution of this model is thought for and involves the coupling of the nonlinear thermohydraulics and electromagnetic equations together with the displacement of the deformable free surface of the weld pool. A first step in the development consisted in modeling the electromagnetic phenomena with two different numerical methods, in comparing the numerical results obtained with those of the literature and in quantifying the importance of the Lorentz force and the Joule effect compared to the other mechanical and thermal sources by computing power balances. Then, in order to assess the predictive capability of the model, simulations of various welding configurations are performed: variation in the chemical composition of the material, of the welding speed, of the prescribed arc pressure and of the welding positions, which is a focus of this work, are studied. A good agreement is obtained between the results of our model and other experimental and numerical results of the literature. Eventually, a model accounting for metal filling is proposed and its results are discussed. Thus, our complete model can be seen as a solid foundation towards future totally-coupled 3D welding models including the arc and it will be included in WPROCESS the in-house CEA software dedicated to the numerical simulation of welding. (author) [fr
Information-preserving models of physics and computation: Final report
International Nuclear Information System (INIS)
1986-01-01
This research pertains to discrete dynamical systems, as embodied by cellular automata, reversible finite-difference equations, and reversible computation. The research has strengthened the cross-fertilization between physics, computer science and discrete mathematics. It has shown that methods and concepts of physics can be exported to computation. Conversely, fully discrete dynamical systems have been shown to be fruitful for representing physical phenomena usually described with differential equations - cellular automata for fluid dynamics has been the most noted example of such a representation. At the practical level, the fully discrete representation approach suggests innovative uses of computers for scientific computing. The originality of these uses lies in their non-numerical nature: they avoid the inaccuracies of floating-point arithmetic and bypass the need for numerical analysis. 38 refs
Do, T. N.; Tjahjowidodo, T.; Lau, M. W. S.; Phee, S. J.
2015-08-01
Natural Orifice Transluminal Endoscopic Surgery (NOTES) is a special method that allows surgical operations via natural orifices like mouth, anus, and vagina, without leaving visible scars. The use of flexible tendon-sheath mechanism (TSM) is common in these systems because of its light weight in structure, flexibility, and easy transmission of power. However, nonlinear friction and backlash hysteresis pose many challenges to control of such systems; in addition, they do not provide haptic feedback to assist the surgeon in the operation of the systems. In this paper, we propose a new dynamic friction model and backlash hysteresis nonlinearity for a pair of TSM to deal with these problems. The proposed friction model, unlike current approaches in the literature, is smooth and able to capture the force at near zero velocity when the system is stationary or operates at small motion. This model can be used to estimate the friction force for haptic feedback purpose. To improve the system tracking performances, a backlash hysteresis model will be introduced, which can be used in a feedforward controller scheme. The controller involves a simple computation of the inverse hysteresis model. The proposed models are configuration independent and able to capture the nonlinearities for arbitrary tendon-sheath shapes. A representative experimental setup is used to validate the proposed models and to demonstrate the improvement in position tracking accuracy and the possibility of providing desired force information at the distal end of a pair of TSM slave manipulator for haptic feedback to the surgeons.
Theoretical and experimental notes on noise phenomena of KUR
International Nuclear Information System (INIS)
Kishida, Kuniharu
1980-01-01
The classification of global or local noise is important in reactor noise analysis. The term of ''global'' or ''local'' corresponds to that of ''system size'' or ''cell size'' in statistical physics. On the other hand, point model or phase space description is used in time series analysis. If a time series model describing spatial behavior is established, it will serve to reactor diagnosis. The noise phenomena of KUR are discussed from these points of view. In other words, from experimental results, the point reactor picture is reasonable to neutronic aspect but quantitative problem remains in coolant temperature fluctuations. By taking into account a diffusion type model, the spatial dependence is discussed for the problem remaining in coolant temperature fluctuations. It is pointed out that the time-space picture is a crucial idea of reactor noise phenomena. (author)
Metamodelling Approach and Software Tools for Physical Modelling and Simulation
Directory of Open Access Journals (Sweden)
Vitaliy Mezhuyev
2015-02-01
Full Text Available In computer science, metamodelling approach becomes more and more popular for the purpose of software systems development. In this paper, we discuss applicability of the metamodelling approach for development of software tools for physical modelling and simulation.To define a metamodel for physical modelling the analysis of physical models will be done. The result of such the analyses will show the invariant physical structures, we propose to use as the basic abstractions of the physical metamodel. It is a system of geometrical objects, allowing to build a spatial structure of physical models and to set a distribution of physical properties. For such geometry of distributed physical properties, the different mathematical methods can be applied. To prove the proposed metamodelling approach, we consider the developed prototypes of software tools.
Standard model physics with the ATLAS early data
Bruckman de Renstrom, Pawel
2006-01-01
The Standard Model, despite its open questions, has proved its consistency and predictive power to very high accuracy within the currently available energy reach. LHC, with its high CM energy and luminosity, will give us insight into new processes, possibly showing evidence of “new physics”. Excellent understanding of the SM processes will also be a key to discriminate against any new phenomena. Prospects of selected SM measurements with the ATLAS detector using early LHC luminosity are presented.
Phase transitions and critical phenomena
Domb, Cyril
2001-01-01
The field of phase transitions and critical phenomena continues to be active in research, producing a steady stream of interesting and fruitful results. It has moved into a central place in condensed matter studies.Statistical physics, and more specifically, the theory of transitions between states of matter, more or less defines what we know about 'everyday' matter and its transformations.The major aim of this serial is to provide review articles that can serve as standard references for research workers in the field, and for graduate students and others wishing to obtain reliable in
International Nuclear Information System (INIS)
Nykyri, M.
2004-10-01
This report considers the present-day understanding and approaches to take into account retention and transport processes in the performance assessment (PA) models used in the evaluation of the long-term safety of deep geological repositories for radioactive waste. It is a product of Work Package 2 in the RETROCK Concerted Action, a part of EURATOM's research and training programme. The processes emphasised in RETROCK are the influences of the flow field, matrix diffusion, and sorption on radionuclide transport characteristics. These processes, and radioactive decay, provide the key terms to the transport equations of the PA models. The following processes are handled more cursorily: colloid-facilitated transport, microbial activity, gas-mediated transport, precipitation/coprecipitation, and off diagonal Onsager processes. The environment in question is saturated sparsely fractured rock in the repository far field. The fracture network offers flow paths for the groundwater transporting radionuclides away from a repository. The radionuclides in various chemical forms interact physically and chemically with other matter in groundwater, fracture surfaces, fracture infills and the rock matrix adjacent to the fractures. These interactions typically result in significant retardation, and decay, of radionuclides compared to the velocity of the groundwater. The PA models usually take into account retention phenomena using simplified concepts that are justified by their conservatism. They are complemented by a large variety of more detailed and realistic process-specific models that can be used to support the choice of data for PA models, as well as specific arguments made in safety cases. While the fundamental understanding, the conceptualisations of the phenomena, the models and the computing resources develop, the extensive data requirements often become a most restrictive factor to the use of a model. The difficulties in obtaining data tend to hinder the utilisation of
Energy Technology Data Exchange (ETDEWEB)
Nykyri, M. [Safram Oy, Espoo (Finland)] [and others
2004-10-01
This report considers the present-day understanding and approaches to take into account retention and transport processes in the performance assessment (PA) models used in the evaluation of the long-term safety of deep geological repositories for radioactive waste. It is a product of Work Package 2 in the RETROCK Concerted Action, a part of EURATOM's research and training programme. The processes emphasised in RETROCK are the influences of the flow field, matrix diffusion, and sorption on radionuclide transport characteristics. These processes, and radioactive decay, provide the key terms to the transport equations of the PA models. The following processes are handled more cursorily: colloid-facilitated transport, microbial activity, gas-mediated transport, precipitation/coprecipitation, and off diagonal Onsager processes. The environment in question is saturated sparsely fractured rock in the repository far field. The fracture network offers flow paths for the groundwater transporting radionuclides away from a repository. The radionuclides in various chemical forms interact physically and chemically with other matter in groundwater, fracture surfaces, fracture infills and the rock matrix adjacent to the fractures. These interactions typically result in significant retardation, and decay, of radionuclides compared to the velocity of the groundwater. The PA models usually take into account retention phenomena using simplified concepts that are justified by their conservatism. They are complemented by a large variety of more detailed and realistic process-specific models that can be used to support the choice of data for PA models, as well as specific arguments made in safety cases. While the fundamental understanding, the conceptualisations of the phenomena, the models and the computing resources develop, the extensive data requirements often become a most restrictive factor to the use of a model. The difficulties in obtaining data tend to hinder the
Silva, J V C; Peixoto, P D S; Lortal, S; Floury, J
2013-10-01
During cheese ripening, microorganisms grow as immobilized colonies, metabolizing substrates present in the matrix and generating products from enzymatic reactions. Local factors that limit the rates of diffusion, either within the general cheese matrix or near the colonies, may influence the metabolic activity of the bacteria during ripening, affecting the final quality of the cheese. The objective of this study was to determine the diffusion coefficients of solutes as a function of their different physicochemical characteristics (size, charge, and shape) in an ultrafiltrate (UF) model cheese (based on ultrafiltered milk) to enable better understanding of the ripening mechanisms. Diffusion coefficients of fluorescein isothiocyanate (FITC)-dextrans (4 kDa to 2 MDa) and FITC-labeled dairy proteins (α-lactalbumin, β-lactoglobulin, and BSA) were measured using the technique of fluorescence recovery after photobleaching (FRAP). This study showed that macromolecules up to 2 MDa and proteins could diffuse through the UF model cheese. The larger FITC-dextrans were not more hindered by the structure of the UF model cheese compared with the smaller ones. Any decrease in the diffusion coefficients of solutes was related only to their hydrodynamic radii. The FITC-dextran diffusion data were fitted to an obstruction model, resulting in a constant obstruction factor (k ~0.42). Diffusion in the model cheese was sensitive to the physicochemical characteristics of the solute. The FITC-dairy proteins studied (rigid and negatively charged molecules) were hindered to a greater degree than the FITC-dextrans (flexible and charge-neutral molecules) in the UF model cheese. The existence of steric and electrostatic interactions between the protein matrix of the UF model cheese and the FITC-dairy proteins could explain the decrease in diffusion compared with FITC-dextrans. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.
Present status of composite models in particle physics
International Nuclear Information System (INIS)
Terazawa, Hidezumi.
1986-03-01
The present status of composite models in particle physics is reviewed with emphasis on the minimal composite model. The subjects to discuss include 1) minimal composite model, 2) generations, 3) mass spectrum and 4) Miyazawa's SUSY and Nambu's SUSY. (author)
Lee, Chi-Seung; Lee, Jae-Myung; Youn, BuHyun; Kim, Hyung-Sik; Shin, Jong Ki; Goh, Tae Sik; Lee, Jung Sub
2017-01-01
A new type of constitutive model and its computational implementation procedure for the simulation of a trabecular bone are proposed in the present study. A yield surface-independent Frank-Brockman elasto-viscoplastic model is introduced to express the nonlinear material behavior such as softening beyond yield point, plateau, and densification under compressive loads. In particular, the hardening- and softening-dominant material functions are introduced and adopted in the plastic multiplier to describe each nonlinear material behavior separately. In addition, the elasto-viscoplastic model is transformed into an implicit type discrete model, and is programmed as a user-defined material subroutine in commercial finite element analysis code. In particular, the consistent tangent modulus method is proposed to improve the computational convergence and to save computational time during finite element analysis. Through the developed material library, the nonlinear stress-strain relationship is analyzed qualitatively and quantitatively, and the simulation results are compared with the results of compression test on the trabecular bone to validate the proposed constitutive model, computational method, and material library. Copyright © 2016 Elsevier Ltd. All rights reserved.
Flavor physics and right-handed models
International Nuclear Information System (INIS)
Shafaq, Saba
2010-01-01
The Standard Model of particle physics only provides a parametrization of flavor which involves the values of the quark and lepton masses and unitary flavor mixing matrix i.e. CKM (Cabibbo-Kobayashi-Masakawa) matrix for quarks. The precise determination of elements of the CKM matrix is important for the study of the flavor sector of quarks. Here we concentrate on the matrix element vertical stroke V cb vertical stroke. In particular we consider the effects on the value of vertical stroke V cb vertical stroke from possible right-handed admixtures along with the usually left-handed weak currents. Left Right Symmetric Model provide a natural basis for right-handed current contributions and has been studied extensively in the literature but has never been discussed including flavor. In the first part of the present work an additional flavor symmetry is included in LRSM which allows a systematic study of flavor effects. The second part deals with the practical extraction of a possible right-handed contribution. Starting from the quark level transition b→c we use heavy quark symmetries to relate the helicities of the quarks to experimentally accessible quantities. To this end we study the decays anti B→D(D * )l anti ν which have been extensively explored close to non recoil point. By taking into account SCET (Soft Collinear Effective Theory) formalism it has been extended to a maximum recoil point i.e. υ . υ ' >>1. We derive a factorization formula, where the set of form factors is reduced to a single universal form factor ξ(υ . υ ' ) up to hard-scattering corrections. Symmetry relations on form factors for exclusive anti B → D(D * )l anti ν transition has been derived in terms of ξ(υ . υ ' ). These symmetries are then broken by perturbative effects. The perturbative corrections to symmetry-breaking corrections to first order in the strong coupling α s are then computed at large recoil regime. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Tsilingiris, P.T. [Department of Energy Engineering, Heat Transfer Laboratory, Technological Education Institution of Athens, A. Spyridonos Street, GR 122 10 Egaleo, Athens (Greece)
2010-02-15
In the present investigation efforts have been devoted towards developing an analysis suitable for heat and mass transfer processes modeling in solar distillation systems, when they are operating at higher temperatures. For this purpose the use of Lewis relation is not new although its validity is based on the assumptions of identical boundary layer concentration and temperature distributions, as well as low mass flux conditions, which are not usually met in solar distillation systems operating at higher temperatures associated with considerable mass transfer rates. The present analysis, taking into consideration these conditions and the temperature dependence of all pertinent thermophysical properties of the saturated binary mixture of water vapor and dry air, leads to the development of an improved predictive accuracy model. This model, having undergone successful first order validation against earlier reported measurements from the literature, appears to offer more accurate predictions of the transport processes and mass flow rate yield of solar stills when operated at elevated temperatures. (author)
DEFF Research Database (Denmark)
Paz-Garcia, Juan Manuel; Johannesson, Björn; Ottosen, Lisbeth M.
2010-01-01
. Electrical neutrality was continuously assured in the model by the inclusion of the Poisson-Boltzmann equation to the system of governing equations. Voltage differences were applied across the sample as boundary conditions in order to evaluate the competition between diffusion and electromigration terms......A model to predict the transport of ionic species within the pore solution of porous materials, under the effect of an external electric field has been developed. A Finite Elements method was implemented and used for the integration of the Nernst-Plank equations for each ionic species considered...
Stamovlasis, D.; Kypraios, N.; Papageorgiou, G.
2015-01-01
In this study, structural equation modeling (SEM) is applied to an instrument assessing students' understanding of chemical change. The instrument comprised items on understanding the structure of substances, chemical changes and their interpretation. The structural relationships among particular groups of items are investigated and analyzed using…
Nanophenomena at surfaces fundamentals of exotic condensed matter phenomena
Michailov, Michail
2011-01-01
This book presents the state of the art in nanoscale surface physics. It outlines contemporary trends in the field covering a wide range of topical areas: atomic structure of surfaces and interfaces, molecular films and polymer adsorption, biologically inspired nanophysics, surface design and pattern formation, and computer modeling of interfacial phenomena. Bridging 'classical' and 'nano' concepts, the present volume brings attention to the physical background of exotic condensed-matter properties. The book is devoted to Iwan Stranski and Rostislaw Kaischew, remarkable scientists, who played
Cheshire cat phenomena and quarks in nuclei
International Nuclear Information System (INIS)
Rho, M.
1986-11-01
The notion of the ''Cheshire Cat'' principle in hadron structure is developed rigorously in (1+1) dimensions and approximately in (3+1) dimensions for up- and down-quark flavor systems. This phenomenon is invoked to address the issue as to whether or not direct quark-gluon signatures can be ''seen'' in low-energy nuclear phenomena. How addition of the third flavor -strangeness- can modify the Cheshire Cat property is discussed. It is proposed that one of the primary objectives of nuclear physics be to probe -and disturb- the ''vacuum'' of the strong interactions (QCD) and that for this purpose the chiral symmetry SU(3)xSU(3) can play a crucial role in normal and extreme conditions. As an illustration, kaon condensation at a density ρ>∼ 3ρ 0 is discussed in terms of a toy model and is related to ''cleansing'' of the quark condensates from the vacuum
Laboratory simulation of space plasma phenomena*
Amatucci, B.; Tejero, E. M.; Ganguli, G.; Blackwell, D.; Enloe, C. L.; Gillman, E.; Walker, D.; Gatling, G.
2017-12-01
Laboratory devices, such as the Naval Research Laboratory's Space Physics Simulation Chamber, are large-scale experiments dedicated to the creation of large-volume plasmas with parameters realistically scaled to those found in various regions of the near-Earth space plasma environment. Such devices make valuable contributions to the understanding of space plasmas by investigating phenomena under carefully controlled, reproducible conditions, allowing for the validation of theoretical models being applied to space data. By working in collaboration with in situ experimentalists to create realistic conditions scaled to those found during the observations of interest, the microphysics responsible for the observed events can be investigated in detail not possible in space. To date, numerous investigations of phenomena such as plasma waves, wave-particle interactions, and particle energization have been successfully performed in the laboratory. In addition to investigations such as plasma wave and instability studies, the laboratory devices can also make valuable contributions to the development and testing of space plasma diagnostics. One example is the plasma impedance probe developed at NRL. Originally developed as a laboratory diagnostic, the sensor has now been flown on a sounding rocket, is included on a CubeSat experiment, and will be included on the DoD Space Test Program's STP-H6 experiment on the International Space Station. In this presentation, we will describe several examples of the laboratory investigation of space plasma waves and instabilities and diagnostic development. *This work supported by the NRL Base Program.
Rheological phenomena in focus
Boger, DV
1993-01-01
More than possibly any other scientific discipline, rheology is easily visualized and the relevant literature contains many excellent photographs of unusual and often bizarre phenomena. The present book brings together these photographs for the first time. They are supported by a full explanatory text. Rheological Phenomena in Focus will be an indispensable support manual to all those who teach rheology or have to convince colleagues of the practical relevance of the subject within an industrial setting. For those who teach fluid mechanics, the book clearly illustrates the difference be
Searches for Beyond Standard Model Physics with ATLAS and CMS
Rompotis, Nikolaos; The ATLAS collaboration
2017-01-01
The exploration of the high energy frontier with ATLAS and CMS experiments provides one of the best opportunities to look for physics beyond the Standard Model. In this talk, I review the motivation, the strategy and some recent results related to beyond Standard Model physics from these experiments. The review will cover beyond Standard Model Higgs boson searches, supersymmetry and searches for exotic particles.
Pivac, Ivan; Šimić, Boris; Barbir, Frano
2017-10-01
Representation of fuel cell processes by equivalent circuit models, involving resistance and capacitance elements representing activation losses on both anode and cathode in series with resistance representing ohmic losses, cannot capture and explain the inductive loop that may show up at low frequencies in Nyquist diagram representation of the electrochemical impedance spectra. In an attempt to explain the cause of the low-frequency inductive loop and correlate it with the processes within the fuel cell electrodes, a novel equivalent circuit model of a Proton Exchange Membrane (PEM) fuel cell has been proposed and experimentally verified here in detail. The model takes into account both the anode and the cathode, and has an additional resonant loop on each side, comprising of a resistance, capacitance and inductance in parallel representing the processes within the catalyst layer. Using these additional circuit elements, more accurate and better fits to experimental impedance data in the wide frequency range at different current densities, cell temperatures, humidity of gases, air flow stoichiometries and backpressures were obtained.
International Nuclear Information System (INIS)
Melendez L, L.
2004-01-01
In the first part of this work, starting from Einstein's equations of the Classical General Relativity, a new kind of solutions for the Mixmaster model are explored. By dispensing with the extension to the complex variable field, which is usual in problems such as the Laplace equation or the harmonic oscillator, in a similar manner to that of Quantum Mechanics, the equations appear to have solutions that belong to the complex General Relativity. A first integral is performed by establishing a separation of the first derivatives. Then a second integral is obtained once the respective equations with separate variables are found and whose integrals provide a family of complex solutions. However, reality conditions do not seem to be easily imposed at this stage. Above all, it is significant that the classical Einstein's equations for the debatably integrable Mixmaster model present complex solutions. In the second part of this work, following a specific strategy in which the cosmological time variables are operated upon, a new family of solutions to the empty Taub universe is found. Among the characteristics of such a family, it stands the positive acceleration provided by the tri-curvature property of this universe to two of the three scale factors of the Taub model. This effect of the tri-curvature results not in a restoring force such as normal gravity but in the conversion of the Taub cosmology into an accelerating universe. (Author)
Teaching Einsteinian Physics at Schools: Part 2, Models and Analogies for Quantum Physics
Kaur, Tejinder; Blair, David; Moschilla, John; Zadnik, Marjan
2017-01-01
The Einstein-First project approaches the teaching of Einsteinian physics through the use of physical models and analogies. This paper presents an approach to the teaching of quantum physics which begins by emphasising the particle-nature of light through the use of toy projectiles to represent photons. This allows key concepts including the…
Modelling Mathematical Reasoning in Physics Education
Uhden, Olaf; Karam, Ricardo; Pietrocola, Mauricio; Pospiech, Gesche
2012-01-01
Many findings from research as well as reports from teachers describe students' problem solving strategies as manipulation of formulas by rote. The resulting dissatisfaction with quantitative physical textbook problems seems to influence the attitude towards the role of mathematics in physics education in general. Mathematics is often seen as a…
Solar Neutrons and Related Phenomena
Dorman, Lev
2010-01-01
This book presents the first comprehensive compilation and review of the extensive body of experimental and theoretical material on solar neutrons and related phenomena published in the scientific literature over the last sixty years. Phenomena related to solar neutrons are more specifically: the decay products of solar neutrons solar gamma rays generated in processes like nuclear reactions between solar energetic charged particles and matter of the solar atmosphere, as well as by the capture of solar neutrons by hydrogen atoms in the solar atmosphere the propagation of solar neutrons, solar gamma rays and other secondary particles through the solar photosphere, chromosphere and corona, as well as through interplanetary space and through the Earth's atmosphere. Models and simulations of particle acceleration, interactions, and propagation processes show that observations of solar neutrons and gamma rays in space and in the Earth's atmosphere yield essential and unique information on the source function of ene...
Directory of Open Access Journals (Sweden)
Davide Papini
2010-01-01
Different condenser tube arrangements have been developed for applications to the next generation NPPs. The two most used configurations, namely, horizontal and vertical tube condensers, are thoroughly investigated in this paper. Several thermal-hydraulic features were explored, being the analysis mainly devoted to the description of the best-estimate correlations and models for heat transfer coefficient prediction. In spite of a more critical behaviour concerning thermal expansion issues, vertical tube condensers offer remarkably better thermal-hydraulic performances. An experimental validation of the vertical tube correlations is provided by PERSEO facility (SIET labs, Piacenza, showing a fairly good agreement.
Physics-Based Pneumatic Hammer Instability Model, Phase I
National Aeronautics and Space Administration — Florida Turbine Technologies (FTT) proposes to conduct research necessary to develop a physics-based pneumatic hammer instability model for hydrostatic bearings...
Three-Dimensional CFD Modeling of Transport Phenomena in a Cross-Flow Anode-Supported Planar SOFC
Directory of Open Access Journals (Sweden)
Zhonggang Zhang
2013-12-01
Full Text Available In this study, a three-dimensional computational fluid dynamics (CFD model is developed for an anode-supported planar SOFC from the Chinese Academy of Science Ningbo Institute of Material Technology and Engineering (NIMTE. The simulation results of the developed model are in good agreement with the experimental data obtained under the same conditions. With the simulation results, the distribution of temperature, flow velocity and the gas concentrations through the cell components and gas channels is presented and discussed. Potential and current density distributions in the cell and overall fuel utilization are also presented. It is also found that the temperature gradients exist along the length of the cell, and the maximum value of the temperature for the cross-flow is at the outlet region of the cell. The distribution of the current density is uneven, and the maximum current density is located at the interfaces between the channels, ribs and the electrodes, the maximum current density result in a large over-potential and heat source in the electrodes, which is harmful to the overall performance and working lifespan of the fuel cells. A new type of flow structure should be developed to make the current flow be more evenly distributed and promote most of the TPB areas to take part in the electrochemical reactions.
Abazari, Alireza; Thompson, Richard B; Elliott, Janet A W; McGann, Locksley E
2012-03-21
Knowledge of the spatial and temporal distribution of cryoprotective agent (CPA) is necessary for the cryopreservation of articular cartilage. Cartilage dehydration and shrinkage, as well as the change in extracellular osmolality, may have a significant impact on chondrocyte survival during and after CPA loading, freezing, and thawing, and during CPA unloading. In the literature, Fick's law of diffusion is commonly used to predict the spatial distribution and overall concentration of the CPA in the cartilage matrix, and the shrinkage and stress-strain in the cartilage matrix during CPA loading are neglected. In this study, we used a previously described biomechanical model to predict the spatial and temporal distributions of CPA during loading. We measured the intrinsic inhomogeneities in initial water and fixed charge densities in the cartilage using magnetic resonance imaging and introduced them into the model as initial conditions. We then compared the prediction results with the results obtained using uniform initial conditions. The simulation results in this study demonstrate the presence of a significant mechanical strain in the matrix of the cartilage, within all layers, during CPA loading. The osmotic response of the chondrocytes to the cartilage dehydration during CPA loading was also simulated. The results reveal that a transient shrinking occurs to different levels, and the chondrocytes experience a significant decrease in volume, particularly in the middle and deep zones of articular cartilage, during CPA loading. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.
Gas-liquid mass transfer and flow phenomena in the Peirce-Smith converter: a water model study
Zhao, Xing; Zhao, Hong-liang; Zhang, Li-feng; Yang, Li-qiang
2018-01-01
A water model with a geometric similarity ratio of 1:5 was developed to investigate the gas-liquid mass transfer and flow characteristics in a Peirce-Smith converter. A gas mixture of CO2 and Ar was injected into a NaOH solution bath. The flow field, volumetric mass transfer coefficient per unit volume ( Ak/V; where A is the contact area between phases, V is the volume, and k is the mass transfer coefficient), and gas utilization ratio ( η) were then measured at different gas flow rates and blow angles. The results showed that the flow field could be divided into five regions, i.e., injection, strong loop, weak loop, splashing, and dead zone. Whereas the Ak/V of the bath increased and then decreased with increasing gas flow rate, and η steadily increased. When the converter was rotated clockwise, both Ak/V and η increased. However, the flow condition deteriorated when the gas flow rate and blow angle were drastically increased. Therefore, these parameters must be controlled to optimal conditions. In the proposed model, the optimal gas flow rate and blow angle were 7.5 m3·h-1 and 10°, respectively.
Estimating Parameters in Physical Models through Bayesian Inversion: A Complete Example
Allmaras, Moritz
2013-02-07
All mathematical models of real-world phenomena contain parameters that need to be estimated from measurements, either for realistic predictions or simply to understand the characteristics of the model. Bayesian statistics provides a framework for parameter estimation in which uncertainties about models and measurements are translated into uncertainties in estimates of parameters. This paper provides a simple, step-by-step example-starting from a physical experiment and going through all of the mathematics-to explain the use of Bayesian techniques for estimating the coefficients of gravity and air friction in the equations describing a falling body. In the experiment we dropped an object from a known height and recorded the free fall using a video camera. The video recording was analyzed frame by frame to obtain the distance the body had fallen as a function of time, including measures of uncertainty in our data that we describe as probability densities. We explain the decisions behind the various choices of probability distributions and relate them to observed phenomena. Our measured data are then combined with a mathematical model of a falling body to obtain probability densities on the space of parameters we seek to estimate. We interpret these results and discuss sources of errors in our estimation procedure. © 2013 Society for Industrial and Applied Mathematics.
Flavor physics and right-handed models
Energy Technology Data Exchange (ETDEWEB)
Shafaq, Saba
2010-08-20
The Standard Model of particle physics only provides a parametrization of flavor which involves the values of the quark and lepton masses and unitary flavor mixing matrix i.e. CKM (Cabibbo-Kobayashi-Masakawa) matrix for quarks. The precise determination of elements of the CKM matrix is important for the study of the flavor sector of quarks. Here we concentrate on the matrix element vertical stroke V{sub cb} vertical stroke. In particular we consider the effects on the value of vertical stroke V{sub cb} vertical stroke from possible right-handed admixtures along with the usually left-handed weak currents. Left Right Symmetric Model provide a natural basis for right-handed current contributions and has been studied extensively in the literature but has never been discussed including flavor. In the first part of the present work an additional flavor symmetry is included in LRSM which allows a systematic study of flavor effects. The second part deals with the practical extraction of a possible right-handed contribution. Starting from the quark level transition b{yields}c we use heavy quark symmetries to relate the helicities of the quarks to experimentally accessible quantities. To this end we study the decays anti B{yields}D(D{sup *})l anti {nu} which have been extensively explored close to non recoil point. By taking into account SCET (Soft Collinear Effective Theory) formalism it has been extended to a maximum recoil point i.e. {upsilon} . {upsilon}{sup '} >>1. We derive a factorization formula, where the set of form factors is reduced to a single universal form factor {xi}({upsilon} . {upsilon}{sup '}) up to hard-scattering corrections. Symmetry relations on form factors for exclusive anti B {yields} D(D{sup *})l anti {nu} transition has been derived in terms of {xi}({upsilon} . {upsilon}{sup '}). These symmetries are then broken by perturbative effects. The perturbative corrections to symmetry-breaking corrections to first order in the strong