Sample records for heterogeneous transport phenomena

  1. Homogeneous and non-local heterogeneous transport phenomena with VAT application analysis

    Energy Technology Data Exchange (ETDEWEB)

    Catton, I.; Travkin, V.S. [Univ. of California, Los Angeles, CA (United States)


    Some fundamental questions about the mathematical description of transport phenomena in heterogeneous media are addressed to highlight the importance of the smallest scale, of using the correct equations and of choosing a consistent set of scaling parameters. Micro-pore flow is treated using a viscosity correlation that properly treats the near wall region in a capillary. Equations resulting from use of volume averaging theory (VAT) are compared with exact solutions and it shown that certain terms normally ignored must be retained. A consistent set of scaling parameters are derived and shown to yield consistent results over a wide range of different media morphologies.

  2. Interfacial transport phenomena

    CERN Document Server

    Slattery, John C; Oh, Eun-Suok


    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.

  3. Transport phenomena II essentials

    CERN Document Server

    REA, The Editors of


    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Transport Phenomena II covers forced convention, temperature distribution, free convection, diffusitivity and the mechanism of mass transfer, convective mass transfer, concentration

  4. Transport phenomena I essentials

    CERN Document Server

    REA, The Editors of


    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Transport Phenomena I includes viscosity, flow of Newtonian fluids, velocity distribution in laminar flow, velocity distributions with more than one independent variable, thermal con

  5. Transport Phenomena in Gel

    Directory of Open Access Journals (Sweden)

    Masayuki Tokita


    Full Text Available Gel becomes an important class of soft materials since it can be seen in a wide variety of the chemical and the biological systems. The unique properties of gel arise from the structure, namely, the three-dimensional polymer network that is swollen by a huge amount of solvent. Despite the small volume fraction of the polymer network, which is usually only a few percent or less, gel shows the typical properties that belong to solids such as the elasticity. Gel is, therefore, regarded as a dilute solid because its elasticity is much smaller than that of typical solids. Because of the diluted structure, small molecules can pass along the open space of the polymer network. In addition to the viscous resistance of gel fluid, however, the substance experiences resistance due to the polymer network of gel during the transport process. It is, therefore, of importance to study the diffusion of the small molecules in gel as well as the flow of gel fluid itself through the polymer network of gel. It may be natural to assume that the effects of the resistance due to the polymer network of gel depends strongly on the network structure. Therefore, detailed study on the transport processes in and through gel may open a new insight into the relationship between the structure and the transport properties of gel. The two typical transport processes in and through gel, that is, the diffusion of small molecules due to the thermal fluctuations and the flow of gel fluid that is caused by the mechanical pressure gradient will be reviewed.

  6. Transport phenomena in multiphase flows

    CERN Document Server

    Mauri, Roberto


    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...

  7. Transport phenomena in particulate systems

    CERN Document Server

    Freire, José Teixeira; Ferreira, Maria do Carmo


    This volume spans 10 chapters covering different aspects of transport phenomena including fixed and fluidized systems, spouted beds, electrochemical and wastewater treatment reactors. This e-book will be valuable for students, engineers and researchers aiming to keep updated on the latest developments on particulate systems.

  8. Transport phenomena in porous media (United States)

    Bear, Jacob; Corapcioglu, M. Yavuz

    The Advanced Study Institute on Fundamentals of Transport Phenomena in Porous Media, held July 14-23, 1985 in Newark, Del. and directed by Jacob Bear (Israel Institute of Technology, Haifa) and M. Yavuz Corapcioglu (City College of New York), under the auspices of NATO, was a sequel to the NATO Advanced Study Institute (ASI) held in 1982 (proceedings published as Fundamentals of Transport Phenomena in Porous Media, J. Bear, and M.Y. Corapcioglu (Ed.), Martinus Nijhoff, Dordrecht, the Netherlands, 1984). The meeting was attended by 106 participants and lecturers from 21 countries.As in the first NATO/ASI, the objective of this meeting—which was a combination of a conference of experts and a teaching institute— was to present and discuss selected topics of transport in porous media. In selecting topics and lecturers, an attempt was made to bridge the gap that sometimes exists between research and practice. An effort was also made to demonstrate the unified approach to the transport of mass of a fluid phase, components of a fluid phase, momentum, and heat in a porous medium domain. The void space may be occupied by a single fluid phase or by a number of such phases; each fluid may constitute a multicomponent system; the solid matrix may be deformable; and the whole process of transport in the system may take place under nonisothermal conditions, with or without phase changes. Such phenomena are encountered in a variety of disciplines, e.g., petroleum engineering, civil engineering (in connection with groundwater flow and contamination), soil mechanics, and chemical engineering. One of the goals of the 1985 NATO/ASI, as in the 1982 institute, was to bring together experts from all these disciplines and enhance communication among them.

  9. Transport phenomena in porous media

    CERN Document Server

    Ingham, Derek B


    Research into thermal convection in porous media has substantially increased during recent years due to its numerous practical applications. These problems have attracted the attention of industrialists, engineers and scientists from many very diversified disciplines, such as applied mathematics, chemical, civil, environmental, mechanical and nuclear engineering, geothermal physics and food science. Thus, there is a wealth of information now available on convective processes in porous media and it is therefore appropriate and timely to undertake a new critical evaluation of this contemporary information. Transport Phenomena in Porous Media contains 17 chapters and represents the collective work of 27 of the world's leading experts, from 12 countries, in heat transfer in porous media. The recent intensive research in this area has substantially raised the expectations for numerous new practical applications and this makes the book a most timely addition to the existing literature. It includes recent major deve...

  10. Transport phenomena an introduction to advanced topics

    CERN Document Server

    Glasgow, Larry A


    Enables readers to apply transport phenomena principles to solve advanced problems in all areas of engineering and science This book helps readers elevate their understanding of, and their ability to apply, transport phenomena by introducing a broad range of advanced topics as well as analytical and numerical solution techniques. Readers gain the ability to solve complex problems generally not addressed in undergraduate-level courses, including nonlinear, multidimensional transport, and transient molecular and convective transport scenarios. Avoiding rote memorization, the author em

  11. A Connection between Transport Phenomena and Thermodynamics (United States)

    Swaney, Ross; Bird, R. Byron


    Although students take courses in transport phenomena and thermodynamics, they probably do not ask whether these two subjects are related. Here we give an answer to that question. Specifically we give relationships between the equations of change for total energy, internal energy, and entropy of transport phenomena and key equations of equilibrium…

  12. Kinetic theory and transport phenomena

    CERN Document Server

    Soto, Rodrigo


    This textbook presents kinetic theory, which is a systematic approach to describing nonequilibrium systems. The text is balanced between the fundamental concepts of kinetic theory (irreversibility, transport processes, separation of time scales, conservations, coarse graining, distribution functions, etc.) and the results and predictions of the theory, where the relevant properties of different systems are computed. The book is organised in thematic chapters where different paradigmatic systems are studied. The specific features of these systems are described, building and analysing the appropriate kinetic equations. Specifically, the book considers the classical transport of charges, the dynamics of classical gases, Brownian motion, plasmas, and self-gravitating systems, quantum gases, the electronic transport in solids and, finally, semiconductors. Besides these systems that are studied in detail, concepts are applied to some modern examples including the quark–gluon plasma, the motion of bacterial suspen...

  13. Transport phenomena in strongly correlated Fermi liquids

    CERN Document Server

    Kontani, Hiroshi


    In conventional metals, various transport coefficients are scaled according to the quasiparticle relaxation time, \\tau, which implies that the relaxation time approximation (RTA) holds well. However, such a simple scaling does not hold in many strongly correlated electron systems, reflecting their unique electronic states. The most famous example would be cuprate high-Tc superconductors (HTSCs), where almost all the transport coefficients exhibit a significant deviation from the RTA results. To better understand the origin of this discrepancy, we develop a method for calculating various transport coefficients beyond the RTA by employing field theoretical techniques. Near the magnetic quantum critical point, the current vertex correction (CVC), which describes the electron-electron scattering beyond the relaxation time approximation, gives rise to various anomalous transport phenomena. We explain anomalous transport phenomena in cuprate HTSCs and other metals near their magnetic or orbital quantum critical poi...

  14. Basic transport phenomena in materials engineering

    CERN Document Server

    Iguchi, Manabu


    This book presents the basic theory and experimental techniques of transport phenomena in materials processing operations. Such fundamental knowledge is highly useful for researchers and engineers in the field to improve the efficiency of conventional processes or develop novel technology. Divided into four parts, the book comprises 11 chapters describing the principles of momentum transfer, heat transfer, and mass transfer in single phase and multiphase systems. Each chapter includes examples with solutions and exercises to facilitate students’ learning. Diagnostic problems are also provided at the end of each part to assess students’ comprehension of the material.  The book is aimed primarily at students in materials science and engineering. However, it can also serve as a useful reference text in chemical engineering as well as an introductory transport phenomena text in mechanical engineering. In addition, researchers and engineers engaged in materials processing operations will find the material use...

  15. Microgravity Transport Phenomena Experiment (MTPE) Overview (United States)

    Mason, Larry W.


    The Microgravity Transport Phenomena Experiment (MTPE) is a fluids experiment supported by the Fundamentals in Biotechnology program in association with the Human Exploration and Development of Space (BEDS) initiative. The MTP Experiment will investigate fluid transport phenomena both in ground based experiments and in the microgravity environment. Many fluid transport processes are affected by gravity. Osmotic flux kinetics in planar membrane systems have been shown to be influenced by gravimetric orientation, either through convective mixing caused by unstably stratified fluid layers, or through a stable fluid boundary layer structure that forms in association with the membrane. Coupled transport phenomena also show gravity related effects. Coefficients associated with coupled transport processes are defined in terms of a steady state condition. Buoyancy (gravity) driven convection interferes with the attainment of steady state, and the measurement of coupled processes. The MTP Experiment measures the kinetics of molecular migration that occurs in fluids, in response to the application of various driving potentials. Three separate driving potentials may be applied to the MTP Experiment fluids, either singly or in combination. The driving potentials include chemical potential, thermal potential, and electrical potential. Two separate fluid arrangements are used to study membrane mediated and bulk fluid transport phenomena. Transport processes of interest in membrane mediated systems include diffusion, osmosis, and streaming potential. Bulk fluid processes of interest include coupled phenomena such as the Soret Effect, Dufour Effect, Donnan Effect, and thermal diffusion potential. MTP Experiments are performed in the Microgravity Transport Apparatus (MTA), an instrument that has been developed specifically for precision measurement of transport processes. Experiment fluids are contained within the MTA fluid cells, designed to create a one dimensional flow geometry

  16. Modeling in transport phenomena a conceptual approach

    CERN Document Server

    Tosun, Ismail


    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

  17. Comprehensive Study of Plasma-Wall Sheath Transport Phenomena (United States)


    approved for public release. 1 Comprehensive Study of Plasma-Wall Sheath Transport Phenomena Final Report 2016 Prof. Mitchell L. R. Walker Georgia...interaction and how both the sheath and the wall material affect the plasma as a whole. The research aims to determine the fundamental transport properties...AFRL-AFOSR-VA-TR-2016-0346 Comprehensive Study of Plasma-Wall Sheath Transport Phenomena MITCHELL WALKER GEORGIA TECH RESEARCH CORPORATION Final

  18. Transport phenomena in Newtonian fluids a concise primer

    CERN Document Server

    Olsson, Per


    This short primer provides a concise and tutorial-style introduction to transport phenomena in Newtonian fluids , in particular the transport of mass, energy and momentum.  The reader will find detailed derivations of the transport equations for these phenomena, as well as selected analytical solutions to the transport equations in some simple geometries. After a brief introduction to the basic mathematics used in the text, Chapter 2, which deals with momentum transport, presents a derivation of the Navier-Stokes-Duhem equation describing the basic flow in a Newtonian fluid.  Also provided at

  19. PREFACE: Transport phenomena in proton conducting media Transport phenomena in proton conducting media (United States)

    Eikerling, Michael


    Proton transport phenomena are of paramount importance for acid-base chemistry, energy transduction in biological organisms, corrosion processes, and energy conversion in electrochemical systems such as polymer electrolyte fuel cells. The relevance for such a plethora of materials and systems, and the ever-lasting fascination with the highly concerted nature of underlying processes drive research across disciplines in chemistry, biology, physics and chemical engineering. A proton never travels alone. Proton motion is strongly correlated with its environment, usually comprised of an electrolyte and a solid or soft host material. For the transport in nature's most benign proton solvent and shuttle, water that is, insights from ab initio simulations, matured over the last 15 years, have furnished molecular details of the structural diffusion mechanism of protons. Excess proton movement in water consists of sequences of Eigen-Zundel-Eigen transitions, triggered by hydrogen bond breaking and making in the surrounding water network. Nowadays, there is little debate about the validity of this mechanism in water, which bears a stunning resemblance to the basic mechanistic picture put forward by de Grotthuss in 1806. While strong coupling of an excess proton with degrees of freedom of solvent and host materials facilitates proton motion, this coupling also creates negative synergies. In general, proton mobility in biomaterials and electrochemical proton conducting media is highly sensitive to the abundance and structure of the proton solvent. In polymer electrolyte membranes, in which protons are bound to move in nano-sized water-channels, evaporation of water or local membrane dehydration due to electro-osmotic coupling are well-known phenomena that could dramatically diminish proton conductivity. Contributions in this special issue address various vital aspects of the concerted nature of proton motion and they elucidate important structural and dynamic effects of solvent

  20. Imaging unsteady three-dimensional transport phenomena

    Indian Academy of Sciences (India)


    Jan 5, 2014 ... The image data can be jointly analysed with the physical laws governing transport and principles of image formation. Hence, with the experiment suitably carried out, three-dimensional physical domains with unsteady processes can be accommodated. Optical methods promise to breach the holy grail of ...

  1. Imaging unsteady three-dimensional transport phenomena

    Indian Academy of Sciences (India)


    Jan 5, 2014 ... interferometry, schlieren imaging, and shadowgraph. Images recorded in these configurations can be analysed to yield time sequences of three-dimensional distributions of the transported variables. Optical methods are non-intrusive, inertia-free and can image cross-sections of the experimental apparatus.

  2. Charge Transport Phenomena in Peptide Molecular Junctions

    Directory of Open Access Journals (Sweden)

    Alessandra Luchini


    Full Text Available Inelastic electron tunneling spectroscopy (IETS is a valuable in situ spectroscopic analysis technique that provides a direct portrait of the electron transport properties of a molecular species. In the past, IETS has been applied to small molecules. Using self-assembled nanoelectronic junctions, IETS was performed for the first time on a large polypeptide protein peptide in the phosphorylated and native form, yielding interpretable spectra. A reproducible 10-fold shift of the I/V characteristics of the peptide was observed upon phosphorylation. Phosphorylation can be utilized as a site-specific modification to alter peptide structure and thereby influence electron transport in peptide molecular junctions. It is envisioned that kinases and phosphatases may be used to create tunable systems for molecular electronics applications, such as biosensors and memory devices.

  3. Coupled electric and transport phenomena in porous media

    NARCIS (Netherlands)

    Li, Shuai


    The coupled electrical and transport properties of clay-containing porous media are the topics of interest in this study. Both experimental and numerical (pore network modeling) techniques are employed to gain insight into the macro-scale interaction between electrical and solute transport phenomena

  4. Travelling wave phenomena in non-heterogeneous tissues

    DEFF Research Database (Denmark)

    Pedersen, Michael


    Disturbances (or information) propagating in heterogeneous biological tissues (or other media) are often modeled by a partial differential equation of the form $$ u''(t,x) +D(x)u'(t,x) +A(x)u(t,x)=f(t,x), $$ for $ 0......Disturbances (or information) propagating in heterogeneous biological tissues (or other media) are often modeled by a partial differential equation of the form $$ u''(t,x) +D(x)u'(t,x) +A(x)u(t,x)=f(t,x), $$ for $ 0...

  5. Modeling and simulation of transport phenomena in ionic gels (United States)

    Leichsenring, Peter; Wallmersperger, Thomas


    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.

  6. Internal and Surface Phenomena in Heterogenous Metal Combustion (United States)

    Dreizin, Edward L.


    The phenomenon of gas dissolution in burning metals was observed in recent metal combustion studies, but it could not be adequately explained by the traditional metal combustion models. The research reported here addresses heterogeneous metal combustion with emphasis on the processes of oxygen penetration inside burning metal and its influence on the metal combustion rate, temperature history, and disruptive burning. The unique feature of this work is the combination of the microgravity environment with a novel micro-arc generator of monodispersed metal droplets, ensuring repeatable formation and ignition of uniform metal droplets with a controllable initial temperature and velocity. Burning droplet temperature is measured in real time with a three wavelength pyrometer. In addition, particles are rapidly quenched at different combustion times, cross-sectioned, and examined using SEM-based techniques to retrieve the internal composition history of burning metal particles. When the initial velocity of a spherical particle is nearly zero, the microgravity environment makes it possible to study the flame structure, the development of flame nonsymmetry, and correlation of the flame shape with the heterogeneous combustion processes.

  7. Modelling of transport phenomena and defects in crystal growth ...

    Indian Academy of Sciences (India)

    ... 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 the growing crystal are discussed, and the propagation and multiplication of these under the action of thermal stresses is discussed.

  8. Transport phenomena in biomedical engineering principles and practices

    CERN Document Server

    Peattie, Robert A; Bronzino, Joseph D


    Biomimetic Systems: Concepts, Design, and Emulation, Robert J. FisherTransport/Reaction Processes in Biology and Medicine, E. N. LightfootMicrovascular Heat Transfer, James W. BaishFluid Dynamics for Bio Systems: Fundamentals and Model Analysis, Robert A. Peattie and Robert J. FisherAnimal Surrogate Systems, Michael L. Shuler, Sarina G. Harris, Xinran Li, and Mandy B. EschArterial Wall Mass Transport: The Possible Role of Blood Phase Resistance in the Localization of Arterial Disease, John M. Tarbell and Yuchen QiuTransport Phenomena and the Microenvironment, Robert J. Fisher and Robert A. PeattieTransport and Drug Delivery through the Blood-Brain Barrier and Cerebrospinal Fluid, Bingmei M. FuInterstitial Transport in the Brain: Principles for Local Drug Delivery, W. Mark SaltzmanSurfactant Transport and Fluid-Structure Interactions during Pulmonary Airway Reopening, David Martin, Anne-Marie Jacob, and Donald P. Gaver IIIIndex.

  9. Computational transport phenomena of fluid-particle systems

    CERN Document Server

    Arastoopour, Hamid; Abbasi, Emad


    This book concerns the most up-to-date advances in computational transport phenomena (CTP), an emerging tool for the design of gas-solid processes such as fluidized bed systems. The authors examine recent work in kinetic theory and CTP and illustrate gas-solid processes’ many applications in the energy, chemical, pharmaceutical, and food industries. They also discuss the kinetic theory approach in developing constitutive equations for gas-solid flow systems and how it has advanced over the last decade as well as the possibility of obtaining innovative designs for multiphase reactors, such as those needed to capture CO2 from flue gases. Suitable as a concise reference and a textbook supplement for graduate courses, Computational Transport Phenomena of Gas-Solid Systems is ideal for practitioners in industries involved with the design and operation of processes based on fluid/particle mixtures, such as the energy, chemicals, pharmaceuticals, and food processing. Explains how to couple the population balance e...

  10. Transport Phenomena and Interfacial Kinetics in Multiphase Combustion Systems (United States)


    Transport phenomena involving the motion of small (mass-)loaded aerosol systems, the literature of this particles suspended in gaseous media and theit depo...flowing nonisothermal gaseous would expect S k to have a similar influence on the media , simultaneously including for the first time the in the tihermal BL and its infuence on the total much larger than the characteristic time re- deposition rate is taken into account. Since the im

  11. 8th International symposium on transport phenomena in combustion

    Energy Technology Data Exchange (ETDEWEB)



    The 8th International Symposium on Transport Phenomena in Combustion will be held in San Francisco, California, U.S.A., July 16-20, 1995, under the auspices of the Pacific Center of Thermal-Fluids Engineering. The purpose of the Symposium is to provide a forum for researchers and practitioners from around the world to present new developments and discuss the state of the art and future directions and priorities in the areas of transport phenomena in combustion. The Symposium is the eighth in a series; previous venues were Honolulu 1985, Tokyo 1987, Taipei 1988, Sydney 1991, Beijing 1992, Seoul 1993 and Acapulco 1994, with emphasis on various aspects of transport phenomena. The current Symposium theme is combustion. The Symposium has assembled a balanced program with topics ranging from fundamental research to contemporary applications of combustion theory. Invited keynote lecturers will provide extensive reviews of topics of great interest in combustion. Colloquia will stress recent advances and innovations in fire spread and suppression, and in low NO{sub x} burners, furnaces, boilers, internal combustion engines, and other practical combustion systems. Finally, numerous papers will contribute to the fundamental understanding of complex processes in combustion. This document contains abstracts of papers to be presented at the Symposium.

  12. Transport phenomena and drying of solids and particulate materials

    CERN Document Server

    Lima, AG


    The purpose of this book, Transport Phenomena and Drying of Solids and Particulate Materials, is to provide a collection of recent contributions in the field of heat and mass transfer, transport phenomena, drying and wetting of solids and particulate materials. The main benefit of the book is that it discusses some of the most important topics related to the heat and mass transfer in solids and particulate materials. It includes a set of new developments in the field of basic and applied research work on the physical and chemical aspects of heat and mass transfer phenomena, drying and wetting processes, namely, innovations and trends in drying science and technology, drying mechanism and theory, equipment, advanced modelling, complex simulation and experimentation. At the same time, these topics will be going to the encounter of a variety of scientific and engineering disciplines. The book is divided in several chapters that intend to be a resume of the current state of knowledge for benefit of professional c...

  13. Modelling of Transport Phenomena at Cement Matrix—Aggregate Interfaces

    DEFF Research Database (Denmark)

    van Breugel, Klaas; Koenders, Eddie; Ye, Guang


    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......-induced moisture transport from the water-rich interfacial zone to the drying bulk paste. Typical features of the simulation model are presented, as well as results of the numerical analysis of the effect of moisture transport within the hardening paste.......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...

  14. Improved Insight into Transport Phenomena in Porous Materials at Submicrometer Resolution

    DEFF Research Database (Denmark)

    Gooya, Reza

    materials at the pore scale. ThŒe coupled program wastested for two cases of chloride transport in a 2D channel and for a 2D ion exchanger.In this thesis, pore scale modeling was presented for several transport phenomenain porous media. ThŒeir agreement with the macroscale properties and the ability....... In this thesis, transport phenomena- including single phaseƒow, two phase ƒow and reactive transport, were investigated at the pore scale. Œe motivationwas to €nd cheaper, easier and faster alternatives to macroscale investigations.In the fi€rst part, single phase ƒuid flƒow models were tested on experimentally......Traditionally it has been challenging to investigate ƒflow properties of porous media becauseof their complex and oft‰en heterogeneous pore geometry. However, these materialsare important for oil and gas, catalysts, fuel cells, groundwater quality, CO2 storageand in medical applications...

  15. 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...

  16. 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)


    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.

  17. Towards an understanding of flows in avalanche transport phenomena (United States)

    Jin, Suying; Ramadan, Nikolas; van Compernolle, Bart; Poulos, Matt J.; Morales, George J.


    Recent heat transport experiments conducted in the Large Plasma Device (LAPD) at UCLA, studying avalanche phenomena at steep cross-magnetic field pressure gradients, suggest that flows play a critical role in the evolution of transport phenomena, motivating further characterization. A ring shaped electron beam source injects sub-ionization energy electrons along the strong background magnetic field within a larger quiescent plasma, creating a hollow, high pressure filament. Two distinct regimes are observed as the density decays; the first characterized by multiple small avalanches producing sudden relaxations of the pressure profile which then recovers under continued heating, and the second signaled by a permanent collapse of the density profile after a global avalanche event, then dominated by drift-Alfven waves. The source is modified from previous experiments to gain active control of the flows by controlling the bias between the emitting ring and surrounding carbon masks. The results of flow measurements obtained using a Mach probe and Langmuir/emissive probe are here presented and compared. An analytical model for the behavior of the electron beam source is also in development. Sponsored by NSF Grant 1619505 and by DOE/NSF at BaPSF.

  18. Transport Phenomena of Water in Molecular Fluidic Channels (United States)

    Vo, Truong Quoc; Kim, Bohung


    In molecular-level fluidic transport, where the discrete characteristics of a molecular system are not negligible (in contrast to a continuum description), the response of the molecular water system might still be similar to the continuum description if the time and ensemble averages satisfy the ergodic hypothesis and the scale of the average is enough to recover the classical thermodynamic properties. However, even in such cases, the continuum description breaks down on the material interfaces. In short, molecular-level liquid flows exhibit substantially different physics from classical fluid transport theories because of (i) the interface/surface force field, (ii) thermal/velocity slip, (iii) the discreteness of fluid molecules at the interface and (iv) local viscosity. Therefore, in this study, we present the result of our investigations using molecular dynamics (MD) simulations with continuum-based energy equations and check the validity and limitations of the continuum hypothesis. Our study shows that when the continuum description is subjected to the proper treatment of the interface effects via modified boundary conditions, the so-called continuum-based modified-analytical solutions, they can adequately predict nanoscale fluid transport phenomena. The findings in this work have broad effects in overcoming current limitations in modeling/predicting the fluid behaviors of molecular fluidic devices.

  19. Freezing in porous media: Phase behavior, dynamics and transport phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Wettlaufer, John S. [Yale Univ., New Haven, CT (United States)


    This research was focused on developing the underlying framework for the mechanisms that control the nature of the solidification of a broad range of porous media. To encompass the scope of porous media under consideration we considered material ranging from a dilute colloidal suspension to a highly packed saturated host matrix with a known geometry. The basic physical processes that occur when the interstitial liquid phase solidifies revealed a host of surprises with a broad range of implications from geophysics to materials science and engineering. We now understand that ostensibly microscopic films of unfrozen liquid control both the equilibrium and transport properties of a highly packed saturated host matrix as well as a rather dilute colloidal suspension. However, our description of the effective medium behavior in these settings is rather different and this sets the stage for the future research based on our past results. Once the liquid phase of a saturated relatively densely packed material is frozen, there is a rich dynamical behavior of particles for example due to the directed motion driven by thermomolecular pressure gradients or the confined Brownian motion of the particles. In quite striking contrast, when one freezes a dilute suspension the behavior can be rather more like that of a binary alloy with the particles playing the role of a ``solute''. We probed such systems quantitatively by (i) using X ray photon correlation spectroscopy (XPCS) and Small Angle X-ray Scattering (SAXS) at the Advanced Photon Source at Argonne (ii) studying the Argonne cell in the laboratory using optical microscopy and imagery (because it is not directly visible while in the vacuum can). (3) analyzed the general transport phenomena within the framework of both irreversible thermodynamics and alloy solidification and (4) applied the results to the study of the redistribution of solid particles in a frozen interstitial material. This research has gone a long way

  20. Spin-Dependent Transport Phenomena in Ferromagnet/Semiconductor Heterostructures (United States)

    Geppert, Chad Christopher

    This dissertation examines several aspects of spin-dependent transport phenomena in epitaxially grown ferromagnet/n-GaAs heterostructures. Further maturation of the field of semiconductor-based spintronics is hindered by difficulties in evaluating device performance across materials systems. Using Fe/n-GaAs and Co2MnSi/n-GaAs heterostructures as a test case, the main goal of this work is to demonstrate how such difficulties may be overcome by (1) specifying a more quantitative framework for evaluating transport parameters and (2) the introduction of a new spin-to-charge conversion phenomenon which may be parameterized by bulk semiconductor parameters. In the introductory chapter, this work is placed in the broader context of developing improved methods for the generation, modulation, and detection of spins. The lateral spin-valve geometry is presented as a concrete example of the typical measurement procedures employed. Chapter 2 presents the charge-based transport properties of these samples and establishes the notation and calculation techniques to be employed in subsequent chapters. In particular, we examine in detail the calculation of the electrochemical potential for a given carrier concentration. Chapter 3 provides a full derivation of the equations governing spin-dependent transport in the large polarization regime. This is applied to the case of extracting spin lifetimes and diffusion rates, demonstrating how quantitative agreement with theoretical predictions may be obtained upon properly accounting for both device geometry and material parameters. Further examination of the boundary conditions applicable to the heterojunctions of these samples demonstrates to what extent device performance may be parameterized across materials systems. Chapter 4 presents experimental observations of a new spin-to-charge conversion phenomenon using a non-magnetic probe. In the presence of a large non-equilibrium spin accumulation, the combination of a non-constant density

  1. Impact of Disorder on Spin Dependent Transport Phenomena

    KAUST Repository

    Saidaoui, Hamed


    The impact of the spin degree of freedom on the transport properties of electrons traveling through magnetic materials has been known since the pioneer work of Mott [1]. Since then it has been demonstrated that the spin angular momentum plays a key role in the scattering process of electrons in magnetic multilayers. This role has been emphasized by the discovery of the Giant Magnetoresistance in 1988 by Fert and Grunberg [2, 3]. Among the numerous applications and effects that emerged in mesoscopic devices two mechanisms have attracted our attention during the course of this thesis: the spin transfer torque and the spin Hall effects. The former consists in the transfer of the spin angular momentum from itinerant carriers to local magnetic moments [4]. This mechanism results in the current-driven magnetization switching and excitations, which has potential application in terms of magnetic data storage and non-volatile memories. The latter, spin Hall effect, is considered as well to be one of the most fascinating mechanisms in condensed matter physics due to its ability of generating non-equilibrium spin currents without the need for any magnetic materials. In fact the spin Hall effect relies only on the presence of the spin-orbit interaction in order to create an imbalance between the majority and minority spins. The objective of this thesis is to investigate the impact of disorder on spin dependent transport phenomena. To do so, we identified three classes of systems on which such disorder may have a dramatic influence: (i) antiferromagnetic materials, (ii) impurity-driven spin-orbit coupled systems and (iii) two dimensional semiconducting electron gases with Rashba spin-orbit coupling. Antiferromagnetic materials - We showed that in antiferromagnetic spin-valves, spin transfer torque is highly sensitive to disorder, which prevents its experimental observation. To solve this issue, we proposed to use either a tunnel barrier as a spacer or a local spin torque using

  2. Numerical modeling transport phenomena in proton exchange membrane fuel cells (United States)

    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

  3. Center for low-gravity fluid mechanics and transport phenomena (United States)

    Kassoy, D. R.; Sani, R. L.


    Research projects in several areas are discussed. Mass transport in vapor phase systems, droplet collisions and coalescence in microgravity, and rapid solidification of undercooled melts are discussed.

  4. Enhanced transport phenomena in CO2 sequestration and CO2 EOR

    NARCIS (Netherlands)

    Farajzadeh, R.


    The results of this thesis give insight into the (mass)-transfer during flow of gases, especially CO2, in various gas-liquid systems. A number of experiments was performed to investigate the transport phenomena through interfaces with and without surfactant monolayers. The observed phenomena have

  5. Diffusion and transport phenomena in a collisional magnetoplasma ...

    Indian Academy of Sciences (India)

    Abstract. Boltzmann-transport equation is analytically solved for two-component mag- netoplasma using Chapman–Enskog analysis to include collisional diffusion transport hav- ing anisotropies in both streaming velocity and temperature components. The modified collisional integrals are analytically solved with flux ...

  6. Diffusion and transport phenomena in a collisional magnetoplasma ...

    Indian Academy of Sciences (India)

    Boltzmann-transport equation is analytically solved for two-component magnetoplasma using Chapman-Enskog analysis to include collisional diffusion transport having anisotropies in both streaming velocity and temperature components. The modified collisional integrals are analytically solved with flux integrals and ...

  7. Interaction between growth and transport phenomena in living mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Grillo, A [DMFCI, Facolta di Ingegneria, Universita di Catania, Viale Andrea Doria 6, 95125 Catania (Italy); Zingali, G [Dottorato di Ricerca in Ingegneria Fisica, Universita di Catania, Viale Andrea Doria 6, 95125 Catania (Italy); Borrello, D [Dottorato di Ricerca in Ingegneria Fisica, Universita di Catania, Viale Andrea Doria 6, 95125 Catania (Italy); Federico, S [HPL - Faculty of Kinesiology, Univesity of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N 1N4 (Canada); Herzog, W [HPL - Faculty of Kinesiology, Univesity of Calgary, 2500 University Drive NW, Calgary, Alberta, T2N 1N4 (Canada); Giaquinta, G [DMFCI, Facolta di Ingegneria, Universita di Catania, Viale Andrea Doria 6, 95125 Catania (Italy)


    Biological growth is regulated by the presence of several chemical substances, and is modulated by thermo-mechanical stimuli. The evolution of chemical substances is described by the advection-diffusion-reaction process of solutes dissolved in the fluid-phase of a biphasic mixture with mass exchange between phases. We present a picture in which growth, by changing material symmetries, modifies the environment in which transport processes take place, and we outline a possible interaction between growth and chemical agents. In order to study this interaction, we use averaging methods to determine the macroscopic counterparts of the transport properties defined at the microscale, and, by writing the macroscopic transport equation in material form, we illustrate how these properties are modulated by growth. In the case of anisotropic growth, such a modulation has a geometric meaning, and is related to both the change of material symmetries, and the development of material inhomogeneities. By regarding growth as a process characterized by a time-scale much slower than that of the transport process of interest, we provide an asymptotic analysis of transport in a growing porous medium based on the adiabatic approximation. We prove that the macroscopic concentration of chemical substances is 'renormalized' by the anisotropy of growth.

  8. Application of transport phenomena analysis technique to cerebrospinal fluid. (United States)

    Lam, C H; Hansen, E A; Hall, W A; Hubel, A


    The study of hydrocephalus and the modeling of cerebrospinal fluid flow have proceeded in the past using mathematical analysis that was very capable of prediction phenomenonologically but not well in physiologic parameters. In this paper, the basis of fluid dynamics at the physiologic state is explained using first established equations of transport phenomenon. Then, microscopic and molecular level techniques of modeling are described using porous media theory and chemical kinetic theory and then applied to cerebrospinal fluid (CSF) dynamics. Using techniques of transport analysis allows the field of cerebrospinal fluid dynamics to approach the level of sophistication of urine and blood transport. Concepts such as intracellular and intercellular pathways, compartmentalization, and tortuosity are associated with quantifiable parameters that are relevant to the anatomy and physiology of cerebrospinal fluid transport. The engineering field of transport phenomenon is rich and steeped in architectural, aeronautical, nautical, and more recently biological history. This paper summarizes and reviews the approaches that have been taken in the field of engineering and applies it to CSF flow.

  9. Concentration polarization: Electrodeposition and transport phenomena at overlimiting current

    DEFF Research Database (Denmark)

    Nielsen, Christoffer Peder

    . Secondly, we investigate concentration polarization in a microchannel with charged walls. We provide full numerical solutions to the transport problem, including the effects of advection and surface conduction in the electric double layers. We show that in large areas of the relevant parameter space...... and the boundary layer model, we reveal a number of issues, which invalidate most previous attempts at modeling microchannel concentration polarization using a slip model. Returning to concentration polarization in a bulk system, we study the effects of water splitting at a permselective membrane. We investigate...... this coupled chemical and transport effect using two simple models of the reaction kinetics. The principal investigations are performed using numerical simulations, but in addition we derive an analytical model for the transport in the system. The analytical model reveals an important link between the current...

  10. Thermo-hydrodynamic transport phenomena in partially wetting ...

    Indian Academy of Sciences (India)

    Single-phase as well as two-phase fluid flows inside mini/micro-channels and capillary tubes are of practical importance in many miniaturized engineering systems. While several issues related to single-phase transport are fairly well understood, two-phase systems still pose challenges for engineering design. Thepresence ...

  11. Straining phenomena in bacteria transport through natural porous media. (United States)

    Díaz, Jaime; Rendueles, Manuel; Díaz, Mario


    Transport of bacteria through natural porous media is an issue of increasing concern arising in several very important environmental processes. These include the percolation of bacteria from fecal waste to drinking water reservoirs, thus leading to a risk for human health, or the bioremediation of contaminated soils in which the bacteria are expected to travel long distances underground in order to reach contaminated areas and degrade chemicals originating from accidental spills. An understanding of bacterial retention and transport mechanisms in porous media would be of great help in the development of models able to predict the distance covered by bacterial suspensions in these situations. Experiments were carried out preparing columns filled of soil and sand, introducing bacteria culture (Escherichia coli, Pseudomona putida, and Listeria innocua) solutions by the top of the column. Breakthrough curves were obtained to see the transport of the bacteria in the column. The transport of different bacteria in the two soils aimed at establishing the relative importance of straining in different conditions. This has enabled us to obtain certain parameters, such as the sticking coefficients derived from the filtration theory or bacterial recoveries after multi-step elution, which aid our understanding of how bacteria are retained by mechanisms different to those usually included in the physico-chemical filtration theory. Several indicators may be used to determine the degree of relevance of straining as a mechanism acting during bacterial transport through porous media. Usually, in natural media, neither straining nor physico-chemical filtration is the sole mechanism contributing to bacterial retention. The retention of bacteria by straining mechanisms can be assessed by means of elution profiles under varying conditions. The inversion of flow in our experiments gave rise to secondary elution peaks, probably originating from bacteria retained in narrow pores According

  12. Spin-transport-phenomena in metals, semiconductors, and insulators

    Energy Technology Data Exchange (ETDEWEB)

    Althammer, Matthias Klaus


    Assuming that one could deterministically inject, transport, manipulate, store and detect spin information in solid state devices, the well-established concepts of charge-based electronics could be transferred to the spin realm. This thesis explores the injection, transport, manipulation and storage of spin information in metallic conductors, semiconductors, as well as electrical insulators. On the one hand, we explore the spin-dependent properties of semiconducting zinc oxide thin films deposited via laser-molecular beam epitaxy (laser-MBE). After demonstrating that the zinc oxide films fabricated during this thesis have excellent structural, electrical, and optical properties, we investigate the spin-related properties by optical pump/probe, electrical injection/optical detection, and all electrical spin valve-based experiments. The two key results from these experiments are: (i) Long-lived spin states with spin dephasing times of 10 ns at 10 K related to donor bound excitons can be optically addressed. (ii) The spin dephasing times relevant for electrical transport-based experiments are {<=} 2 ns at 10 K and are correlated with structural quality. On the other hand we focus on two topics of current scientific interest: the comparison of the magnetoresistance to the magnetothermopower of conducting ferromagnets, and the investigation of pure spin currents generated in ferromagnetic insulator/normal metal hybrid structures. We investigate the magnetoresistance and magnetothermopower of gallium manganese arsenide and Heusler thin films as a function of external magnetic field orientation. Using a series expansion of the resistivity and Seebeck tensors and the inherent symmetry of the sample's crystal structure, we show that a full quantitative extraction of the transport tensors from such experiments is possible. Regarding the spin currents in ferromagnetic insulator/normal metal hybrid structures we studied the spin mixing conductance in yttrium iron garnet

  13. The physics of nanoelectronics transport and fluctuation phenomena at low temperatures

    CERN Document Server

    Heikkila, Tero T


    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...

  14. Electric Transport Phenomena of Nanocomposite Organic Polymer Thin Films (United States)

    Jira, Nicholas C.; Sabirianov, Ildar; Ilie, Carolina C.

    We discuss herein the nanocomposite organic thin film diodes for the use of plasmonic solar cells. This experimental work follows the theoretical calculations done for plasmonic solar cells using the MNPBEM toolbox for MatLab. These calculations include dispersion curves and amount of light scattering cross sections for different metallic nanoparticles. This study gives us clear ideas on what to expect from different metals, allowing us to make the best choice on what to use to obtain the best results. One specific technique for light trapping in thin films solar cells utilizes metal nanoparticles on the surface of the semiconductor. The characteristics of the metal, semiconductor interface allows for light to be guided in between them causing it to be scattered, allowing for more chances of absorption. The samples were fabricated using organic thin films made from polymers and metallic nanoparticles, more specifically Poly(1-vinylpyrrolidone-co-2-dimethylaminoethyl methacrylate) copolymer and silver or gold nanoparticles. The two fabrication methods applied include spin coating and Langmuir-Blodgett technique. The transport properties are obtained by analyzing the I-V curves. We will also discuss the resistance, resistivity, conductance, density of charge carriers. SUNY Oswego SCAC Grant.

  15. Combining Deterministic structures and stochastic heterogeneity for transport modeling (United States)

    Zech, Alraune; Attinger, Sabine; Dietrich, Peter; Teutsch, Georg


    Contaminant transport in highly heterogeneous aquifers is extremely challenging and subject of current scientific debate. Tracer plumes often show non-symmetric but highly skewed plume shapes. Predicting such transport behavior using the classical advection-dispersion-equation (ADE) in combination with a stochastic description of aquifer properties requires a dense measurement network. This is in contrast to the available information for most aquifers. A new conceptual aquifer structure model is presented which combines large-scale deterministic information and the stochastic approach for incorporating sub-scale heterogeneity. The conceptual model is designed to allow for a goal-oriented, site specific transport analysis making use of as few data as possible. Thereby the basic idea is to reproduce highly skewed tracer plumes in heterogeneous media by incorporating deterministic contrasts and effects of connectivity instead of using unimodal heterogeneous models with high variances. The conceptual model consists of deterministic blocks of mean hydraulic conductivity which might be measured by pumping tests indicating values differing in orders of magnitudes. A sub-scale heterogeneity is introduced within every block. This heterogeneity can be modeled as bimodal or log-normal distributed. The impact of input parameters, structure and conductivity contrasts is investigated in a systematic manor. Furthermore, some first successful implementation of the model was achieved for the well known MADE site.

  16. Magnetic Resonance Microscopy of Scale Dependent Transport Phenomena and Bioactivity in Porous Media (United States)

    Seymour, J. D.; Codd, S. L.; Romanenko, K. V.; Hornemann, J. A.; Brosten, T. R.


    Magnetic resonance microscopy (MRM) provides the ability to obtain data on the pore scale via imaging and the sample scale by bulk measurement, allowing for connection between microscale dynamics and macroscale transport phenomena. This has led to MRM techniques becoming a preeminent method for characterization of dynamics in porous media. A significant question in modeling transport in porous media is definition of the porous media structure as homogeneous (ordered) or heterogeneous (disordered)[1]. One means of defining the 'complexity' of a porous media is based on the dynamics of the system[2]. The ability of MRM to measure the time dependent statistics of the dynamics [3,4,5] provides quantification of the pre-asymptotic dynamics. The transition from preasymptotic to Gaussian transport consistent with models of homogeneous porous media is clearly visualized. Biological activity in porous media, such as microbial growth, typically manifests itself as biofilms or colonies of microbes that adhere to surfaces and are surrounded by a hydrogel of extracellular polymeric substance (EPS). The biofilm growth introduces complexity into the system structure in generation of physical pore blocking, trapping within the EPS gel, elastic interfaces due to the EPS and generation of channels in which faster flow occur. The hierarchy of length and time scales and multiple physical processes which are introduced by the biofilm growth impacts the porous media transport as reflected in the change in dynamics [6]. The transition can be modeled using statistical mechanical approaches based on continuous time random walk (CTRW) processes that generate fractional differential equations[7]. The bioactivity alters the structure of the porous media from homogeneous to heterogeneous resulting in the transition from a Gaussian to a non Gaussian subdiffusive dispersion process. References 1. M. Quintard and S. Whitaker, Transport in ordered and disordered porous media: Volume averaged

  17. Retrieval of dispersive and convective transport phenomena in fluids using stationary and nonstationary time domain analysis (United States)

    Stephens, J. B.; St.john, R. M.


    Simultaneously occuring dispersive and convective components of fluid kinematics are obtained by a time domain analysis of optically retrieved temporal histories of the transport phenomena. Utilizing triangulation of collimated optical fields of view from two radiometers to obtain the temporal histories of the intensity fluctuations associated with the transport phenomena has enabled investigators to retrieve the local convective transport by employing correlation statistics. The location of the peak in the covariance curve determines the transit time from which the convection velocity is calculated; whereas, the change in shape of the peak in the covariance curve determines the change in average frequency of the wave packet from which the dispersion velocity is calculated. Thus, two-component analysis requires the maximum possible enhancement of the delineation for the transport. The convection velocity is the result of a fixed reference frame calculation whereas, the dispersion velocity is the result of a moving reference frame calcuation.

  18. Charge transport, injection, and photovoltaic phenomena in oligo(phenylenevinylene) based diodes

    NARCIS (Netherlands)

    Melzer, Christian; Krasnikov, Victor V.; Hadziioannou, Georges


    We report on the charge transport and injection phenomena of (E,E,E,E)-1,4-bis[(4-styryl)styryl]-2-methoxy-5-(2'-ethylhexoxy)benzene (MEH-OPV5) sandwiched between asymmetric contacts. The hole mobility of MEH-OPV5 was determined by means of transient electroluminescence. The steady-state current was

  19. Undergraduate Laboratory Experiment Facilitating Active Learning of Concepts in Transport Phenomena: Experiment with a Subliming Solid (United States)

    Utgikar, Vivek P.


    An experiment based on the sublimation of a solid was introduced in the undergraduate Transport Phenomena course. The experiment required the students to devise their own apparatus and measurement techniques. The theoretical basis, assignment of the experiment, experimental results, and student/instructor observations are described in this paper.…

  20. Lattice Boltzmann modeling of transport phenomena in fuel cells and flow batteries (United States)

    Xu, Ao; Shyy, Wei; Zhao, Tianshou


    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.

  1. Spin-related transport phenomena in HgTe-based quantum well structures

    Energy Technology Data Exchange (ETDEWEB)

    Koenig, Markus


    Within the scope of this thesis, spin related transport phenomena have been investigated in HgTe/Hg{sub 0.3}Cd{sub 0.7}Te quantum well structures. In our experiments, the existence of the quantum spin Hall (QSH) state was successfully demonstrated for the first time and the presented results provide clear evidence for the charge transport properties of the QSH state. Our experiments provide the first direct observation of the Aharonov-Casher (AC) effect in semiconductor structures. In conclusion, HgTe quantum well structures have proven to be an excellent template for studying spin-related transport phenomena: The QSH relies on the peculiar band structure of the material and the existence of both the spin Hall effect and the AC effect is a consequence of the substantial spin-orbit interaction. (orig.)

  2. 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


    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.

  3. Center for Electrocatalysis, Transport Phenomena, and Materials (CETM) for Innovative Energy Storage - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Soloveichik, Grigorii [GE Global Research, Niskayuna, New York (United States)


    EFRC vision. The direct use of organic hydrides in fuel cells as virtual hydrogen carriers that generate stable organic molecules, protons, and electrons upon electro-oxidation and can be electrochemically charged by re-hydrogenating the oxidized carrier was the major focus of the Center for Electrocatalysis, Transport Phenomena and Materials for Innovative Energy Storage (EFRC-ETM). Compared to a hydrogen-on-demand design that includes thermal decomposition of organic hydrides in a catalytic reactor, the proposed approach is much simpler and does not require additional dehydrogenation catalysts or heat exchangers. Further, this approach utilizes the advantages of a flow battery (i.e., separation of power and energy, ease of transport and storage of liquid fuels) with fuels that have system energy densities similar to current hydrogen PEM fuel cells. EFRC challenges. Two major EFRC challenges were electrocatalysis and transport phenomena. The electrocatalysis challenge addresses fundamental processes which occur at a single molecular catalyst (microscopic level) and involve electron and proton transfer between the hydrogen rich and hydrogen depleted forms of organic liquid fuel and the catalyst. To form stable, non-radical dehydrogenation products from the organic liquid fuel, it is necessary to ensure fast transport of at least two electrons and two protons (per double bond formation). The same is true for the reverse hydrogenation reaction. The transport phenomena challenge addresses transport of electrons to/from the electrocatalyst and the current collector as well as protons across the polymer membrane. Additionally it addresses prevention of organic liquid fuel, water and oxygen transport through the PEM. In this challenge, the transport of protons or molecules involves multiple sites or a continuum (macroscopic level) and water serves as a proton conducting medium for the majority of known sulfonic acid based PEMs. Proton transfer in the presence of

  4. Final report, BWR drywell debris transport Phenomena Identification and Ranking Tables (PIRTs)

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, G.E. [Lockheed Idaho Technologies Co., Idaho Falls, ID (United States); Boyack, B.E. [Los Alamos National Lab., NM (United States); Leonard, M.T.; Williams, K.A.; Wolf, L.T.


    The Nuclear Regulatory Commission has issued a Regulatory Bulletin and accompanying Regulatory Guide (1.82, Rev. 2) which requires licensees of boiling water reactors to develop a specific plan of action (including hardware backfits, if necessary) to preclude the possibility of early emergency core cooling system strainer blockage following a postulated loss-of-coolant-accident. The postulated mechanism for strainer blockage is destruction of piping insulation in the vicinity of the break and subsequent transport of fragmented insulation to the wetwell. In the absence of more definitive information, the Regulatory Guide recommends that licensees assume a drywell debris transport fraction of 1.0. Accordingly, the Nuclear Regulatory Commission initiated research focused toward developing a technical basis to provide insights useful to regulatory oversight of licensee submittals associated with resolution of the postulated strainer blockage issue. Part of this program was directed towards experimental and analytical research leading to a more realistic specification of the debris transport through the drywell to the wetwell. To help focus this development into a cost effective effort, a panel, with broad based knowledge and experience, was formed to address the relative importance of the various phenomena that can be expected in plant response to postulated accidents that may produce strainer blockage. The resulting phenomena identification and ranking tables reported herein were used to help guide research. The phenomena occurring in boiling water reactors drywells was the specific focus of the panel, although supporting experimental data and calculations of debris transport fractions were considered.

  5. Impact of mineralogical heterogeneity on reactive transport modelling (United States)

    Liu, Min; Shabaninejad, Mehdi; Mostaghimi, Peyman


    Impact of mineralogical heterogeneity of rocks in reactive modelling is investigated by applying a pore scale model based on the Lattice Boltzmann and Finite Volume Methods. Mass transport, chemical reaction and solid structure modification are included in the model. A two-dimensional mineral map of a sandstone rock is acquired using the imaging technique of QEMSCAN SEM with Energy-Dispersive X-ray Spectroscopy (EDS). The mineralogical heterogeneity is explored by conducting multi-mineral reaction simulations on images containing various minerals. The results are then compared with the prediction of single mineral dissolution modelling. Dissolution patterns and permeability variations of multi-mineral and single mineral reactions are presented. The errors of single mineral reaction modelling are also estimated. Numerical results show that mineralogical heterogeneity can cause significant errors in permeability prediction, if a uniform mineral distribution is assumed. The errors are smaller in high Péclet regimes than in low Péclet regimes in this sample.

  6. Regional gas transport in the heterogeneous lung during oscillatory ventilation. (United States)

    Herrmann, Jacob; Tawhai, Merryn H; Kaczka, David W


    Regional ventilation in the injured lung is heterogeneous and frequency dependent, making it difficult to predict how an oscillatory flow waveform at a specified frequency will be distributed throughout the periphery. To predict the impact of mechanical heterogeneity on regional ventilation distribution and gas transport, we developed a computational model of distributed gas flow and CO2 elimination during oscillatory ventilation from 0.1 to 30 Hz. The model consists of a three-dimensional airway network of a canine lung, with heterogeneous parenchymal tissues to mimic effects of gravity and injury. Model CO2 elimination during single frequency oscillation was validated against previously published experimental data (Venegas JG, Hales CA, Strieder DJ, J Appl Physiol 60: 1025-1030, 1986). Simulations of gas transport demonstrated a critical transition in flow distribution at the resonant frequency, where the reactive components of mechanical impedance due to airway inertia and parenchymal elastance were equal. For frequencies above resonance, the distribution of ventilation became spatially clustered and frequency dependent. These results highlight the importance of oscillatory frequency in managing the regional distribution of ventilation and gas exchange in the heterogeneous lung. Copyright © 2016 the American Physiological Society.

  7. Transport phenomena in alkaline direct ethanol fuel cells for sustainable energy production (United States)

    An, L.; Zhao, T. S.


    Alkaline direct ethanol fuel cells (DEFC), which convert the chemical energy stored in ethanol directly into electricity, are one of the most promising energy-conversion devices for portable, mobile and stationary power applications, primarily because this type of fuel cell runs on a carbon-neutral, sustainable fuel and the electrocatalytic and membrane materials that constitute the cell are relatively inexpensive. As a result, the alkaline DEFC technology has undergone a rapid progress over the last decade. This article provides a comprehensive review of transport phenomena of various species in this fuel cell system. The past investigations into how the design and structural parameters of membrane electrode assemblies and the operating parameters affect the fuel cell performance are discussed. In addition, future perspectives and challenges with regard to transport phenomena in this fuel cell system are also highlighted.

  8. 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.


    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.

  9. Chaos suppression and desynchronization phenomena in periodically coupled pendula subjected to localized heterogeneous forces

    Energy Technology Data Exchange (ETDEWEB)

    Chacon, R. [Departamento de Fisica Aplicada, Escuela de Ingenierias Industriales, Universidad de Extremadura, Apartado Postal 382, E-06071 Badajoz (Spain)], E-mail:; Martinez, P.J. [Departamento de Fisica Aplicada, E.U.I.T.I., Universidad de Zaragoza, Spain and Instituto de Ciencia de Materiales de Aragon, CSIC-Universidad de Zaragoza, E-50009 Zaragoza (Spain); Martinez, J.A. [Departamento de Ingenieria Electrica, Electronica y Automatica, E.P.S., Universidad de Castilla-La Mancha, E-02071 Albacete (Spain); Lenci, S. [Dipartimento di Architettura, Costruzioni e Strutture, Universita Politecnica delle Marche, via Brecce Bianche, 60131 Ancona (Italy)


    The suppressory effects of localized heterogeneous periodic pulses on the chaotic behaviour of sinusoidally coupled nonlinear pendula are studied. We assume that when the pendula are driven synchronously, i.e., all driving pulses have the same waveform, the chains display chaotic dynamics. It is shown that decreasing the impulse transmitted by the pulses of a minimal number of pendula results in regularization with the whole array exhibiting frequency synchronization over a wide range of coupling periods. These findings demonstrate that decreasing the impulse transmitted by localized external forces can tame chaos and lead to frequency-locked states in networks of periodically coupled dissipative systems.

  10. Scaling of flow and transport behavior in heterogeneous groundwater systems (United States)

    Scheibe, Timothy; Yabusaki, Steven


    Three-dimensional numerical simulations using a detailed synthetic hydraulic conductivity field developed from geological considerations provide insight into the scaling of subsurface flow and transport processes. Flow and advective transport in the highly resolved heterogeneous field were modeled using massively parallel computers, providing a realistic baseline for evaluation of the impacts of parameter scaling. Upscaling of hydraulic conductivity was performed at a variety of scales using a flexible power law averaging technique. A series of tests were performed to determine the effects of varying the scaling exponent on a number of metrics of flow and transport behavior. Flow and transport simulation on high-performance computers and three-dimensional scientific visualization combine to form a powerful tool for gaining insight into the behavior of complex heterogeneous systems. Many quantitative groundwater models utilize upscaled hydraulic conductivity parameters, either implicitly or explicitly. These parameters are designed to reproduce the bulk flow characteristics at the grid or field scale while not requiring detailed quantification of local-scale conductivity variations. An example from applied groundwater modeling is the common practice of calibrating grid-scale model hydraulic conductivity or transmissivity parameters so as to approximate observed hydraulic head and boundary flux values. Such parameterizations, perhaps with a bulk dispersivity imposed, are then sometimes used to predict transport of reactive or non-reactive solutes. However, this work demonstrates that those parameters that lead to the best upscaling for hydraulic conductivity and head do not necessarily correspond to the best upscaling for prediction of a variety of transport behaviors. This result reflects the fact that transport is strongly impacted by the existence and connectedness of extreme-valued hydraulic conductivities, in contrast to bulk flow which depends more strongly on

  11. Analysis of transport phenomena and electrochemical reactions in a micro PEM fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Sadiq Al-Baghdadi, Maher A.R. [Fuel Cell Research Center, International Energy and Environment Foundation, Najaf, P.O.Box 39 (Iraq)


    Micro-fuel cells are considered as promising electrochemical power sources in portable electronic devices. The presence of microelectromechanical system (MEMS) technology makes it possible to manufacture the miniaturized fuel cell systems. The majority of research on micro-scale fuel cells is aimed at micro-power applications. Performance of micro-fuel cells are closely related to many factors, such as designs and operating conditions. CFD modeling and simulation for heat and mass transport in micro PEM fuel cells are being used extensively in researches and industrial applications to gain better understanding of the fundamental processes and to optimize the micro fuel cell designs before building a prototype for engineering application. In this research, full three-dimensional, non-isothermal computational fluid dynamics model of a micro proton exchange membrane (PEM) fuel cell has been developed. This comprehensive model accounts for the major transport phenomena such as convective and diffusive heat and mass transfer, electrode kinetics, transport and phase-change mechanism of water, and potential fields in a micro PEM fuel cell. The model explains many interacting, complex electrochemical, and transport phenomena that cannot be studied experimentally. Three-dimensional results of the species profiles, temperature distribution, potential distribution, and local current density distribution are presented and analysed, with the focus on the physical insight and fundamental understanding.

  12. Hierarchical modeling of plasma and transport phenomena in a dielectric barrier discharge reactor (United States)

    Bali, N.; Aggelopoulos, C. A.; Skouras, E. D.; Tsakiroglou, C. D.; Burganos, V. N.


    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.

  13. Understanding transport phenomena in electrochemical energy devices via X-ray nano CT (United States)

    Tjaden, B.; Lane, J.; Brett, D. J. L.; Shearing, P. R.


    Porous support layers in electrochemical devices ensure mechanical stability of membrane assemblies such as solid oxide fuel cells and oxygen transport membranes (OTMs). At the same time, porous layers affect diffusive mass transport of gaseous reactants and contribute to performance losses at high fuel utilisation and conversion ratios. Microstructural characteristics are vital to calculate mass transport phenomena, where tortuosity remains notoriously difficult to determine. Here, the tortuosity of tubular porous support layers of OTMs is evaluated via high resolution X-ray nano computed tomography. The high resolution reveals the complex microstructure of the samples to then execute a selection of image-based tortuosity calculation algorithms. Visible differences between geometric and flux-based algorithms are observed and have thus to be applied with caution.


    Directory of Open Access Journals (Sweden)



    Full Text Available In the engineering courses the field of Transport Phenomena is of significant importance and it is in several disciplines relating to Fluid Mechanics, Heat and Mass Transfer. In these disciplines, problems involving these phenomena are mathematically formulated and analytical solutions are obtained whenever possible. The aim of this paper is to emphasize the possibility of extending aspects of the teaching-learning in this area by a method based on time scales and limit solutions. Thus, aspects relative to the phenomenology naturally arise during the definition of the scales and / or by determining the limit solutions. Aspects concerning the phenomenology of the limit problems are easily incorporated into the proposed development, which contributes significantly to the understanding of physics inherent in the mathematical modeling of each limiting case studied. Finally the study aims to disseminate the use of the limit solutions and of the time scales in the general fields of engineering.

  15. Characterization of transport phenomena in porous transport layers using X-ray microtomography (United States)

    Hasanpour, S.; Hoorfar, M.; Phillion, A. B.


    Among different methods available for estimating the transport properties of porous transport layers (PTLs) of polymer electrolyte membrane fuel cells, X-ray micro computed tomography (X-μCT) imaging in combination with image-based numerical simulation has been recognized as a viable tool. In this study, four commercially-available single-layer and dual-layer PTLs are analyzed using this method in order to compare and contrast transport properties between different PTLs, as well as the variability within a single sheet. Complete transport property datasets are created for each PTL. The simulation predictions indicate that PTLs with high porosity show considerable variability in permeability and effective diffusivity, while PTLs with low porosity do not. Furthermore, it is seen that the Tomadakis-Sotirchos (TS) analytical expressions for porous media match the image-based simulations when porosity is relatively low but predict higher permeability and effective diffusivity for porosity values greater than 80%. Finally, the simulations show that cracks within MPL of dual-layer PTLs have a significant effect on the overall permeability and effective diffusivity of the PTLs. This must be considered when estimating the transport properties of dual-layer PTLs. These findings can be used to improve macro-scale models of product and reactant transport within fuel cells, and ultimately, fuel cell efficiency.

  16. Lattice Boltzmann simulation of thermofluidic transport phenomena in a DC magnetohydrodynamic (MHD) micropump. (United States)

    Chatterjee, Dipankar; Amiroudine, Sakir


    A comprehensive non-isothermal Lattice Boltzmann (LB) algorithm is proposed in this article to simulate the thermofluidic transport phenomena encountered in a direct-current (DC) magnetohydrodynamic (MHD) micropump. Inside the pump, an electrically conducting fluid is transported through the microchannel by the action of an electromagnetic Lorentz force evolved out as a consequence of the interaction between applied electric and magnetic fields. The fluid flow and thermal characteristics of the MHD micropump depend on several factors such as the channel geometry, electromagnetic field strength and electrical property of the conducting fluid. An involved analysis is carried out following the LB technique to understand the significant influences of the aforementioned controlling parameters on the overall transport phenomena. In the LB framework, the hydrodynamics is simulated by a distribution function, which obeys a single scalar kinetic equation associated with an externally imposed electromagnetic force field. The thermal history is monitored by a separate temperature distribution function through another scalar kinetic equation incorporating the Joule heating effect. Agreement with analytical, experimental and other available numerical results is found to be quantitative.

  17. Charge transport, injection, and photovoltaic phenomena in oligo(phenylenevinylene) based diodes


    Melzer, Christian; Krasnikov, Victor V.; Hadziioannou, Georges


    We report on the charge transport and injection phenomena of (E,E,E,E)-1,4-bis[(4-styryl)styryl]-2-methoxy-5-(2'-ethylhexoxy)benzene (MEH-OPV5) sandwiched between asymmetric contacts. The hole mobility of MEH-OPV5 was determined by means of transient electroluminescence. The steady-state current was injection-limited. The electric field and temperature dependence of the current were quantitatively described by a phenomenological injection model of thermally assisted charge-carrier tunneling i...

  18. Transport Phenomena in Multilayered Massless Dirac Fermion System α-(BEDT-TTF2I3

    Directory of Open Access Journals (Sweden)

    Naoya Tajima


    Full Text Available A zero-gap state with a Dirac cone type energy dispersion was discovered in an organic conductor α-(BEDT-TTF2I3 under high hydrostatic pressures. This is the first two-dimensional (2D zero-gap state discovered in bulk crystals with a layered structure. In contrast to the case of graphene, the Dirac cone in this system is highly anisotropic. The present system, therefore, provides a new type of massless Dirac fermion system with anisotropic Fermi velocity. This system exhibits remarkable transport phenomena characteristic to electrons on the Dirac cone type energy structure.

  19. Spatial heterogeneity in biogeochemical transport on Arctic hill slopes (United States)

    Risser, R.; Harms, T.; Jones, J.


    Water tracks, saturated regions of the hill slope in permafrosted Arctic catchments, likely deliver the majority of water entering streams in these regions, and may play a central role in delivery of nutrients. Fate of dissolved nutrients and carbon as they are transported in water tracks has a substantial effect on stream ecosystems, as water tracks may cover up to 35% of the catchment land area. Water tracks are distinguished from adjacent areas of the hillslope by higher rates of hydrologic transport, greater woody biomass, and increased pools of nutrients. Substantial spatial heterogeneity within and between water tracks may influence their role in transfer of materials between the terrestrial and aquatic landscape. We examined spatial variability of hydrologic and chemical characteristics within and between water tracks in the Kuparuk Basin of northern Alaska to increase understanding of the factors influencing nutrient export from arctic catchments. We studied a sedge-dominated water track with perennial surface water flow with shrub-dominated water tracks containing intermittent surface flow. Nominal transit times of water in the perennial site was 5 hours, compared to 15.5 h in an ephemeral track over a 50 meter reach, indicating substantial variation in water residence time and opportunity for biogeochemical reaction across sites. We evaluated spatial heterogeneity in biogeochemical characteristics within 25-m reaches at each site with a grain size of 10 m. Dissolved CH4 concentration was elevated above atmospheric equilibrium only at the perennial water track, where CH4 concentration varied by more than 15-fold within the water track, indicating hot spots of anaerobic microbial activity. Dissolved CO2 concentration was 9 times greater on average at the perennial water track, compared to the ephemeral site, suggesting that continuous water flow supports more rapid microbial activity. CO2 concentration was also more variable in the perennial water track

  20. Prediction of bedload sediment transport for heterogeneous sediments in shape (United States)

    Durafour, Marine; Jarno, Armelle; Le Bot, Sophie; Lafite, Robert; Marin, François


    Key words: Particle shape, in-situ measurements, bedload transport, heterogeneous sediments Bedload sediment transport in the coastal area is a dynamic process mainly influenced by the type of hydrodynamic forcings involved (current and/or waves), the flow properties (velocity, viscosity, depth) and sediment heterogeneity (particle size, density, shape). Although particle shape is recognized to be a significant factor in the hydrodynamic behavior of grains, this parameter is not currently implemented in bedload transport formulations: firstly because the mechanisms of initiation of motion according to particle shape are still not fully understood, and secondly due to the difficulties in defining common shape parameters. In March 2011, a large panel of in-situ instruments was deployed on two sites in the Eastern English Channel, during the sea campaign MESFLUX11. Samples of the sediment cover available for transport are collected, during a slack period, per 2cm thick strata by divers and by using a Shipeck grab. Bedload discharges along a tidal cycle are also collected with a Delft Nile Sampler (DNS; Gaweesh and Van Rijn, 1992, 1994) on both sites. The first one is characterized by a sandy bed with a low size dispersion, while the other study area implies graded sediments from fine sands to granules. A detailed analysis of the data is performed to follow the evolution of in-situ bedload fluxes on the seabed for a single current. In-situ measurements are compared to existing formulations according to a single fraction approach, using the median diameter of the mixture, and a fractionwise approach, involving a discretization of the grading curve. Results emphasize the interest to oscillate between these two methods according to the dispersion in size of the site considered. The need to apply a hiding/exposure coefficient (Egiazaroff, 1965) and a hindrance factor (Kleinhans and Van Rijn, 2002) for size heterogeneous sediments is also clearly highlighted. A really good

  1. Dynamics of Coupled Contaminant and Microbial Transport in Heterogeneous Porous Media: Purdue Component

    Energy Technology Data Exchange (ETDEWEB)

    Cushman, J.H.


    Dynamic microbial attachment/detachment occurs in subsurface systems in response to changing environmental conditions caused by contaminant movement and degradation. Understanding the environmental conditions and mechanisms by which anaerobic bacteria partition between aqueous and solid phases is a critical requirement for designing and evaluating in situ bioremediation efforts. This interdisciplinary research project, of which we report only the Purdue contribution, provides fundamental information on the attachment/detachment dynamics of bacteria in heterogeneous porous media. Fundamental results from the Purdue collaboration are: (a) development of a matched-index method for obtaining 3-D Lagrangian trajectories of microbial sized particles transporting within porous media or microflow cells, (b) application of advanced numerical methods to optimally design a microflow cell for studying anaerobic bacterial attachment/detachment phenomena, (c) development of two types of models for simulating bacterial movement and attachment/detachment in microflow cells and natural porous media, (d) application of stochastic analysis to upscale pore scale microbial attachment/detachment models to natural heterogeneous porous media, and (e) evaluation of the role nonlocality plays in microbial dynamics in heterogeneous porous media.

  2. Dynamics of Coupled Contaminant and Microbial Transport in Heterogeneous Porous Media: Purdue Component

    Energy Technology Data Exchange (ETDEWEB)

    Cushman, J.H.; Madilyn Fletcher


    Dynamic microbial attachment/detachment occurs in subsurface systems in response to changing environmental conditions caused by contaminant movement and degradation. Understanding the environmental conditions and mechanisms by which anaerobic bacteria partition between aqueous and solid phases is a critical requirement for designing and evaluating in situ bioremediation efforts. This interdisciplinary research project, of which we report only the Purdue contribution, provides fundamental information on the attachment/detachment dynamics of bacteria in heterogeneous porous media. Fundamental results from the Purdue collaboration are: (a) development of a matched-index method for obtaining 3-D Lagrangian trajectories of microbial sized particles transporting within porous media or microflow cells, (b) application of advanced numerical methods to optimally design a microflow cell for studying anaerobic bacterial attachment/detachment phenomena, (c) development of two types of models for simulating bacterial movement and attachment/detachment in microflow cells and natural porous media, (d) application of stochastic analysis to upscale pore scale microbial attachment/detachment models to natural heterogeneous porous media, and (e) evaluation of the role nonlocality plays in microbial dynamics in heterogeneous porous media

  3. Frontiers in transport phenomena research and education: Energy systems, biological systems, security, information technology and nanotechnology

    Energy Technology Data Exchange (ETDEWEB)

    Bergman, T.L.; Faghri, A. [Department of Mechanical Engineering, The University of Connecticut, Storrs, CT 06269-3139 (United States); Viskanta, R. [School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907-2088 (United States)


    A US National Science Foundation-sponsored workshop entitled ''Frontiers in Transport Phenomena Research and Education: Energy Systems, Biological Systems, Security, Information Technology, and Nanotechnology'' was held in May of 2007 at the University of Connecticut. The workshop provided a venue for researchers, educators and policy-makers to identify frontier challenges and associated opportunities in heat and mass transfer. Approximately 300 invited participants from academia, business and government from the US and abroad attended. Based upon the final recommendations on the topical matter of the workshop, several trends become apparent. A strong interest in sustainable energy is evident. A continued need to understand the coupling between broad length (and time) scales persists, but the emerging need to better understand transport phenomena at the macro/mega scale has evolved. The need to develop new metrology techniques to collect and archive reliable property data persists. Societal sustainability received major attention in two of the reports. Matters involving innovation, entrepreneurship, and globalization of the engineering profession have emerged, and the responsibility to improve the technical literacy of the public-at-large is discussed. Integration of research thrusts and education activities is highlighted throughout. Specific recommendations, made by the panelists with input from the international heat transfer community and directed to the National Science Foundation, are included in several reports. (author)

  4. Advanced modelling of the transport phenomena across horizontal clothing microclimates with natural convection. (United States)

    Mayor, T S; Couto, S; Psikuta, A; Rossi, R M


    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

  5. The Hydrodynamics and Odorant Transport Phenomena of Olfaction in the Hammerhead Shark (United States)

    Rygg, Alex; Craven, Brent


    The hammerhead shark possesses a unique head morphology that is thought to facilitate enhanced olfactory performance. The olfactory organs, located at the distal ends of the cephalofoil, contain numerous lamellae that increase the surface area for olfaction. Functionally, for the shark to detect chemical stimuli, water-borne odors must reach the olfactory sensory epithelium that lines these lamellae. Thus, odorant transport from the aquatic environment to the sensory epithelium is the first critical step in olfaction. Here we investigate the hydrodynamics and odorant transport phenomena of olfaction in the hammerhead shark based on an anatomically-accurate reconstruction of the head and olfactory chamber from high-resolution micro-CT and MRI scans of a cadaver specimen. Computational fluid dynamics (CFD) simulations of water flow in the reconstructed model reveal the external and internal hydrodynamics of olfaction during swimming. Odorant transport in the olfactory organ is investigated using a multi-scale approach, whereby molecular dynamics (MD) simulations are used to calculate odorant partition coefficients that are subsequently utilized in macro-scale CFD simulations of odorant deposition. The hydrodynamic and odorant transport results are used to elucidate several important features of olfactory function in the hammerhead shark.

  6. A heterogeneous model for gas transport in carbon molecular sieves. (United States)

    Ding, L P; Yuan, Y X; Farooq, S; Bhatia, S K


    A dual resistance model with distribution of either barrier or pore diffusional activation energy is proposed in this work for gas transport in carbon molecular sieve (CMS) micropores. This is a novel approach in which the equilibrium is homogeneous, but the kinetics is heterogeneous. The model seems to provide a possible explanation for the concentration dependence of the thermodynamically corrected barrier and pore diffusion coefficients observed in previous studies from this laboratory on gas diffusion in CMS. The energy distribution is assumed to follow the gamma distribution function. It is shown that the energy distribution model can fully capture the behavior described by the empirical model established in earlier studies to account for the concentration dependence of thermodynamically corrected barrier and pore diffusion coefficients. A methodology is proposed for extracting energy distribution parameters, and it is further shown that the extracted energy distribution parameters can effectively predict integral uptake and column breakthrough profiles over a wide range of operating pressures.

  7. Sorption, degradation and transport phenomena of alcohol ethoxysulfates in agricultural soils. Laboratory studies. (United States)

    Fernández-Ramos, C; Rodríguez-Gómez, R; Reis, M S; Zafra-Gómez, A; Verge, C; de Ferrer, J A; Pérez-Pascual, M; Vílchez, J L


    In the present work, laboratory studies were conducted in order to determine and model the sorption, degradation and transport processes of alcohol ethoxysulfates (AES), one of the most important groups of anionic surfactants. Adsorption/desorption isotherms were obtained for several structurally related AES ethoxymers (homologue AES-C12En with n = 0-10 ethoxymer units and homologue AES-C14En with n = 0-7 ethoxymer units) using a batch equilibrium method. Data were fitted to a linear and a Freundlich isotherm models. Additionally, experiments in continuous-flow soil columns were also carried out and the breakthrough curves observed for each compound were studied. Breakthrough curves were used to determine the fundamental parameters of the transport model (hydrodynamic dispersion coefficient, degradation rate constant and adsorption/desorption isotherm slope), that is the main phenomena that take place simultaneously when AES move through agricultural soil. When the results obtained for the AES ethoxymers are combined, they reveal a clear and consistent trend towards a sorption increase with the number of ethoxylated units and with the length of the alkyl chain that opens the possibility to estimate the values of the transport parameters for other structurally related ethoxymers. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Fundamentals of Melt-Water Interfacial Transport Phenomena: Improved Understanding for Innovative Safety Technologies in ALWRs

    Energy Technology Data Exchange (ETDEWEB)

    M. Anderson; M. Corradini; K.Y. Bank; R. Bonazza; D. Cho


    The interaction and mixing of high-temperature melt and water is the important technical issue in the safety assessment of water-cooled reactors to achieve ultimate core coolability. For specific advanced light water reactor (ALWR) designs, deliberate mixing of the core-melt and water is being considered as a mitigative measure, to assure ex-vessel core coolability. The goal of this work is to provide the fundamental understanding needed for melt-water interfacial transport phenomena, thus enabling the development of innovative safety technologies for advanced LWRs that will assure ex-vessel core coolability. The work considers the ex-vessel coolability phenomena in two stages. The first stage is the melt quenching process and is being addressed by Argonne National Lab and University of Wisconsin in modified test facilities. Given a quenched melt in the form of solidified debris, the second stage is to characterize the long-term debris cooling process and is being addressed by Korean Maritime University in via test and analyses. We then address the appropriate scaling and design methodologies for reactor applications.

  9. Mathematical study of transport phenomena along a tuyere of the Teniente converter

    Directory of Open Access Journals (Sweden)


    Full Text Available This paper presents a comprehensive mathematical model of transport phenomena which occur along a tuyere of the Teniente converter during injection of oxygen-enriched air. Inlet pressure, gas velocity and temperature, the dimensions of the tuyere, and the properties of gas are the basic data. From these inputs, temperature distribution of the refractory walls of the converter around the tuyere as well as the velocity, pressure, and the Mach number along the pipe can be calculated. In this model, the heat transfer through the metal jacket of the tuyere and the refractory lining are duly taken into account. More precisely, a mathematical model is developed where the equations of momentum and energy of the gas are coupled with the equations of heat transfer inside the solid part. This new model couples a partial differential equation in the solid part with four ordinary differential equations in the gas flow.

  10. Transport Phenomena in Porous Media Aspects of MicroMacro Behaviour

    CERN Document Server

    Ichikawa, Yasuaki


    This monograph presents an integrated perspective of the wide range of phenomena and processes applicable to the study of transport of species in porous materials. In order to formulate the entire range of porous media and their uses, this book gives the basics of continuum mechanics, thermodynamics, seepage and consolidation and diffusion, including multiscale homogenization methods. The particular structure of the book has been chosen because it is essential to be aware of the true properties of porous materials particularly in terms of nano, micro and macro mechanisms.  This book is of pedagogical and practical importance to the fields covered by civil, environmental, nuclear and petroleum engineering and also in chemical physics and geophysics as it relates to radioactive waste disposal, geotechnical engineering, mining and petroleum engineering and chemical engineering.

  11. Transport phenomena and kinetic theory applications to gases, semiconductors, photons, and biological systems

    CERN Document Server

    Gabetta, Ester


    The study of kinetic equations related to gases, semiconductors, photons, traffic flow, and other systems has developed rapidly in recent years because of its role as a mathematical tool in many applications in areas such as engineering, meteorology, biology, chemistry, materials science, nanotechnology, and pharmacy. Written by leading specialists in their respective fields, this book presents an overview of recent developments in the field of mathematical kinetic theory with a focus on modeling complex systems, emphasizing both mathematical properties and their physical meaning. The overall presentation covers not only modeling aspects and qualitative analysis of mathematical problems, but also inverse problems, which lead to a detailed assessment of models in connection with their applications, and to computational problems, which lead to an effective link of models to the analysis of real-world systems. "Transport Phenomena and Kinetic Theory" is an excellent self-study reference for graduate students, re...

  12. Combining geoelectrical and advanced lysimeter methods to characterize heterogeneous flow and transport under unsaturated transient conditions (United States)

    Wehrer, M.; Skowronski, J.; Binley, A. M.; Slater, L. D.


    Our ability to predict flow and transport processes in the unsaturated critical zone is considerably limited by two characteristics: heterogeneity of flow and transience of boundary conditions. The causes of heterogeneous - or preferential - flow and transport are fairly well understood, yet the characterization and quantification of such processes in natural profiles remains challenging. This is due to current methods of observation, such as staining and isotope tracers, being unable to observe multiple events on the same profile and offering limited spatial information. In our study we demonstrate an approach to characterize preferential flow and transport processes applying a combination of geoelectrical methods and advanced lysimeter techniques. On an agricultural soil profile, which was transferred undisturbed into a lysimeter container, we applied systematically varied input flow boundary conditions, resembling natural precipitation events. We simultaneously measured the breakthrough of a conservative tracer. Flow and transport in the soil column were observed using electrical resistivity tomography (ERT), tensiometers, water content probes and a multicompartment suction plate (MSP). These techniques allowed a direct ground-truthing of soil moisture and pore fluid resistivity changes estimated noninvasively using ERT. We were able to image both the advancing infiltration front and the advancing tracer front using time lapse ERT. Water content changes associated with the advancing infiltration front dominated over pore fluid conductivity changes during short term precipitation events. Conversely, long term displacement of the solute front was monitored during periods of constant water content in between infiltration events. We observed preferential flow phenomena through ERT and through the MSP, which agreed in general terms. The preferential flow fraction was observed to be independent of precipitation rate. This suggests the presence of a fingering process

  13. Transport lattice models of heat transport in skin with spatially heterogeneous, temperature-dependent perfusion

    Directory of Open Access Journals (Sweden)

    Martin Gregory T


    Full Text Available Abstract Background Investigation of bioheat transfer problems requires the evaluation of temporal and spatial distributions of temperature. This class of problems has been traditionally addressed using the Pennes bioheat equation. Transport of heat by conduction, and by temperature-dependent, spatially heterogeneous blood perfusion is modeled here using a transport lattice approach. Methods We represent heat transport processes by using a lattice that represents the Pennes bioheat equation in perfused tissues, and diffusion in nonperfused regions. The three layer skin model has a nonperfused viable epidermis, and deeper regions of dermis and subcutaneous tissue with perfusion that is constant or temperature-dependent. Two cases are considered: (1 surface contact heating and (2 spatially distributed heating. The model is relevant to the prediction of the transient and steady state temperature rise for different methods of power deposition within the skin. Accumulated thermal damage is estimated by using an Arrhenius type rate equation at locations where viable tissue temperature exceeds 42°C. Prediction of spatial temperature distributions is also illustrated with a two-dimensional model of skin created from a histological image. Results The transport lattice approach was validated by comparison with an analytical solution for a slab with homogeneous thermal properties and spatially distributed uniform sink held at constant temperatures at the ends. For typical transcutaneous blood gas sensing conditions the estimated damage is small, even with prolonged skin contact to a 45°C surface. Spatial heterogeneity in skin thermal properties leads to a non-uniform temperature distribution during a 10 GHz electromagnetic field exposure. A realistic two-dimensional model of the skin shows that tissue heterogeneity does not lead to a significant local temperature increase when heated by a hot wire tip. Conclusions The heat transport system model of the

  14. Heat science and transport phenomena in fuel cells; Thermique et phenomenes de transport dans les piles a combustible

    Energy Technology Data Exchange (ETDEWEB)

    Liberatore, P.M.; Boillot, M. [Laboratoire des Sciences du Genie Chimique de Nancy, 54 - Vandoeuvre-les-Nancy (France); Bonnet, C.; Didieerjean, S.; Lapicque, F.; Deseure, J.; Lottin, O.; Maillet, D.; Oseen-Senda, J. [Laboratoire d' Energetique et de Mecanique Theorique et Appliquee, 54 - Vandoeuvre Les Nancy (France); Alexandre, A. [Laboratoire d' Etudes Thermiques, ENSMA, 86 Poitiers (France); Topin, F.; Occelli, R.; Daurelle, J.V. [IUSTI / Polytech' Marseille, Institut universitaire des Systemes Thermiques Industriels Ecole, 13 - Marseille (France); Pauchet, J.; Feidt, M. [CEA Grenoble, Groupement pour la recherche sur les echangeurs thermiques (Greth), 38 (France); Voarino, C. [CEA Centre d' Etudes du Ripault, 37 - Tours (France); Morel, B.; Laurentin, J.; Bultel, Y.; Lefebvre-Joud, F. [CEA Grenoble, LEPMI, 38 (France); Auvity, B.; Lasbet, Y.; Castelain, C.; Peerohossaini, H. [Ecole Centrale de Nantes, Laboratoire de Thermocinetique de Nantes (LTN), 44 - Nantes (France)


    In this work are gathered the transparencies of the lectures presented at the conference 'heat science and transport phenomena in fuel cells'. The different lectures have dealt with 1)the gas distribution in the bipolar plates of a fuel cell: experimental studies and computerized simulations 2)two-phase heat distributors in the PEMFC 3)a numerical study of the flow properties of the backing layers on the transfers in a PEMFC 4)modelling of the heat and mass transfers in a PEMFC 5)two-phase cooling of the PEMFC with pentane 6)stationary thermodynamic model of the SOFC in the GECOPAC system 7)modelling of the internal reforming at the anode of the SOFC 8)towards a new thermal design of the PEMFC bipolar plates. (O.M.)

  15. Analytical and experimental analysis of solute transport in heterogeneous porous media. (United States)

    Wu, Lei; Gao, Bin; Tian, Yuan; Muñoz-Carpena, Rafael


    Knowledge of solute transport in heterogeneous porous media is crucial to monitor contaminant fate and transport in soil and groundwater systems. In this study, we present new findings from experimental and mathematical analysis to improve current understanding of solute transport in structured heterogeneous porous media. Three saturated columns packed with different sand combinations were used to examine the breakthrough behavior of bromide, a conservative tracer. Experimental results showed that bromide had different breakthrough responses in the three types of sand combinations, indicating that heterogeneity in hydraulic conductivity has a significant effect on the solute transport in structured heterogeneous porous media. Simulations from analytical solutions of a two-domain solute transport model matched experimental breakthrough data well for all the experimental conditions tested. Experimental and model results show that under saturated flow conditions, advection dominates solute transport in both fast-flow and slow-flow domains. The sand with larger hydraulic conductivity provided a preferential flow path for solute transport (fast-flow domain) that dominates the mass transfer in the heterogeneous porous media. Importantly, the transport in the slow-flow domain and mass exchange between the domains also contribute to the flow and solute transport processes and thus must be considered when investigating contaminant transport in heterogeneous porous media.

  16. The application of the Chebyshev-spectral method in transport phenomena

    CERN Document Server

    Guo, Weidong; Narayanan, Ranga


    Transport phenomena problems that occur in engineering and physics are often multi-dimensional and multi-phase in character.  When taking recourse to numerical methods the spectral method is particularly useful and efficient. The book is meant principally to train students and non-specialists  to use the spectral method for solving problems that model fluid flow in closed geometries with heat or mass transfer.  To this aim the reader should bring a working knowledge of fluid mechanics and heat transfer and should be readily conversant with simple concepts of linear algebra including spectral decomposition of matrices as well as solvability conditions for inhomogeneous problems.  The book is neither meant to supply a ready-to-use program that is all-purpose nor to go through all manners of mathematical proofs.  The focus in this tutorial is on the use of the spectral methods for space discretization, because this is where most of the difficulty lies. While time dependent problems are also of great interes...

  17. Multiparameter Analysis of Gas Transport Phenomena in Shale Gas Reservoirs: Apparent Permeability Characterization. (United States)

    Shen, Yinghao; Pang, Yu; Shen, Ziqi; Tian, Yuanyuan; Ge, Hongkui


    The large amount of nanoscale pores in shale results in the inability to apply Darcy's law. Moreover, the gas adsorption of shale increases the complexity of pore size characterization and thus decreases the accuracy of flow regime estimation. In this study, an apparent permeability model, which describes the adsorptive gas flow behavior in shale by considering the effects of gas adsorption, stress dependence, and non-Darcy flow, is proposed. The pore size distribution, methane adsorption capacity, pore compressibility, and matrix permeability of the Barnett and Eagle Ford shales are measured in the laboratory to determine the critical parameters of gas transport phenomena. The slip coefficients, tortuosity, and surface diffusivity are predicted via the regression analysis of the permeability data. The results indicate that the apparent permeability model, which considers second-order gas slippage, Knudsen diffusion, and surface diffusion, could describe the gas flow behavior in the transition flow regime for nanoporous shale. Second-order gas slippage and surface diffusion play key roles in the gas flow in nanopores for Knudsen numbers ranging from 0.18 to 0.5. Therefore, the gas adsorption and non-Darcy flow effects, which involve gas slippage, Knudsen diffusion, and surface diffusion, are indispensable parameters of the permeability model for shale.

  18. Transport Phenomena Projects: Natural Convection between Porous, Concentric Cylinders--A Method to Learn and to Innovate (United States)

    Saatadjian, Esteban; Lesage, Francois; Mota, Jose Paulo B.


    A project that involves the numerical simulation of transport phenomena is an excellent method to teach this subject to senior/graduate chemical engineering students. The subject presented here has been used in our senior/graduate course, it concerns the study of natural convection heat transfer between two concentric, horizontal, saturated porous…

  19. Contaminant transport in fracture networks with heterogeneous rock matrices. The Picnic code

    Energy Technology Data Exchange (ETDEWEB)

    Barten, Werner [Paul Scherrer Inst., CH-5232 Villigen PSI (Switzerland); Robinson, Peter C. [QuantiSci Limited, Henley-on-Thames (United Kingdom)


    In the context of safety assessment of radioactive waste repositories, complex radionuclide transport models covering key safety-relevant processes play a major role. In recent Swiss safety assessments, such as Kristallin-I, an important drawback was the limitation in geosphere modelling capability to account for geosphere heterogeneities. In marked contrast to this limitation in modelling capabilities, great effort has been put into investigating the heterogeneity of the geosphere as it impacts on hydrology. Structural geological methods have been used to look at the geometry of the flow paths on a small scale and the diffusion and sorption properties of different rock materials have been investigated. This huge amount of information could however be only partially applied in geosphere transport modelling. To make use of these investigations the 'PICNIC project' was established as a joint cooperation of PSI/Nagra and QuantiSci to provide a new geosphere transport model for Swiss safety assessment of radioactive waste repositories. The new transport code, PICNIC, can treat all processes considered in the older geosphere model RANCH MD generally used in the Kristallin-I study and, in addition, explicitly accounts for the heterogeneity of the geosphere on different spatial scales. The effects and transport phenomena that can be accounted for by PICNIC are a combination of (advective) macro-dispersion due to transport in a network of conduits (legs), micro-dispersion in single legs, one-dimensional or two-dimensional matrix diffusion into a wide range of homogeneous and heterogeneous rock matrix geometries, linear sorption of nuclides in the flow path and the rock matrix and radioactive decay and ingrowth in the case of nuclide chains. Analytical and numerical Laplace transformation methods are integrated in a newly developed hierarchical linear response concept to efficiently account for the transport mechanisms considered which typically act on extremely

  20. A Model for Transport Phenomena in a Cross-Flow Ultrafiltration Module with Microchannels (United States)

    Nishimoto, Aiko; Yoshikawa, Shiro; Ookawara, Shinichi


    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. PMID:24957492

  1. TTF/TCNQ-based thin films and microcrystals. Growth and charge transport phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Solovyeva, Vita


    The thesis adresses several problems related to growth and charge transport phenomena in thin films of TTF-TCNQ and (BEDT-TTF)TCNQ. The following main new problems are addressed: - The influence of thin-film specific factors, such as the substrate material and growth-induced defects, on the Peierls transition temperature in TTF-TCNQ thin films was studied; - finite-size effects in TTF-TCNQ were investigated by considering transport properties in TTF-TCNQ microcrystals. The influence of the size of the crystal on the Peierls transition temperature was studied. In this context a new method of microcontact fabrication was employed to favor the measurements; - an analysis of radiation-induced defects in TTF-TCNQ thin films and microcrystals was performed. It was demonstrated than an electron beam can induce appreciable damage to the sample such that its electronic properties are strongly modified; - a bilayer growth method was established to fabricate (BEDT-TTF)TCNQ from the gas phase. This newly developed bilayer growth method was showed to be suitable for testing (BEDT-TTF)TCNQ charge-transfer phase formation; - the structure of the formed (BEDT-TTF)TCNQ charge-transfer compounds was analyzed by using a wide range of experimental techniques. An overview and the description of the basic physical principles underlying charge-transfer compounds is given in chapter 2. Experimental techniques used for the growth and characterization of thin films and microcrystals are presented in chapter 3. Chapter 4 gives an overview of the physical properties of the studied organic materials. Chapter 5 discussed the experimental study of TTF-TCNQ thin films. he Peierls transition in TTF-TCNQ is a consequence of the quasi-one-dimensional structure of the material and depends on different factors, studied in chapters 5 and 6. In contradistinction to TTF-TTCNQ, the (BEDT-TTF)TCNQ charge-transfer compound crystallizes in several different modifications with different physical properties

  2. Investigation of nanostructured electrocatalysts and mass transport phenomena in polymer electrolyte fuel cells (United States)

    Goenaga, Gabriel A.

    Proton exchange membrane (PEM) fuel cells (FC) are promising devices in the search of clean and efficient technologies to reduce the use of fossil fuels. However, their poor performance in dynamic applications and high cost of platinum group metal (PGM) catalysts, have prevented them from becoming an affordable solution. This dissertation comprehend three research projects that study the mass transport phenomena in modified PEMs, the reduction of the amount of PGM catalyst used for oxygen reduction reaction (ORR) and the use of non-PGM catalysts as alternative catalyst to Pt for ORR. Nafion is the most used PEM for FC applications. Nafion proton conductivity is proportional to its degree of hydration, what imposes low temperature operation to maintain appropriate water content. In this research, Nafion composite membranes doped with hydrophilic metal inorganic particles have been studied using pulse field gradient (PFG) nuclear magnetic resonance (NMR). The Nafion composite membranes were found to have higher water uptake, higher water retention, higher water diffusion and, in some cases, lower methanol diffusion (crossover) than the filler free Nafion membrane. The amount of Pt and PGM catalysts supported on carbon used in the electrodes, has a great impact in the PEMFC cost. In particular, it is of high relevance to reduce the amount of Pt in the cathode electrode, in which the sluggish ORR demands four to five times more Pt catalyst than in the anode. In this thesis is shown that the use of aligned carbon nanotubes (ACNTs) as Pt support, allows a more uniform distribution of the Pt nanoparticles, what in addition to their high hydrophobicity and high corrosive resistance, lead to improved mass transport and stability of the membrane electrode assembly (MEA), when compared to a benchmark MEA that uses Pt catalyst supported on carbon black. The improvement was accomplished using less Pt than in the benchmark MEA. Replacing Pt with non-PGM catalyst can lead to an

  3. Transport Phenomena in Nanowires, Nanotubes, and Other Low-Dimensional Systems

    KAUST Repository

    Montes, Enrique


    Nanoscale materials are not new in either nature or physics. However, the recent technological improvements have given scientists new tools to understand and quantify phenomena that occur naturally due to quantum confinement effects. In general, these phenomena induce remarkable optical, magnetic, and electronic properties in nanoscale materials in contrast to their bulk counterpart. In addition, scientists have recently developed the necessary tools to control and exploit these properties in electronic devices, in particular field effect transistors, magnetic memories, and gas sensors. In the present thesis we implement theoretical and computational tools for analyzing the ground state and electronic transport properties of nanoscale materials and their performance in electronic devices. The ground state properties are studied within density functional theory using the SIESTA code, whereas the transport properties are investigated using the non-equilibrium Green\\'s functions formalism implemented in the SMEAGOL code. First we study Si-based systems, as Si nanowires are believed to be important building blocks of the next generation of electronic devices. We derive the electron transport properties of Si nanowires connected to Au electrodes and their dependence on the nanowire growth direction, diameter, and length. At equilibrium Au-nanowire distance we find strong electronic coupling between electrodes and nanowire, resulting in low contact resistance. For the tunneling regime, the decay of the conductance with the nanowire length is rationalized using the complex band structure. The nanowires grown along the (110) direction show the smallest decay and the largest conductance and current. Due to the high spin coherence in Si, Si nanowires represent an interesting platform for spin devices. Therefore, we built a magnetic tunneling junction by connecting a (110) Si nanowire to ferromagnetic Fe electrodes. We have find a substantial low bias magnetoresistance of

  4. Role of Transport Phenomena in the Evolution of Geometry, Composition and Structure

    Energy Technology Data Exchange (ETDEWEB)

    Tarasankar DebRoy


    Abstract Fusion welding is used extensively in industries that support the nation's energy supply, defense, infrastructure, and standard of living. Safety and reliability of the welded joints are affected by their geometry, composition and structure. This report provides an account of the significant advances made in quantitative understanding of the geometry, composition and various aspects of the weldment structure with financial support from DOE/BES. In particular, this report provides an account of the research conducted under the grant DE-FG02-84ER45158 in this important area and lists all the publications that document the details of the technical accomplishments that resulted from the work. Investigations of heat transfer, fluid flow and alloying element vaporization during laser welding resulted in a new technique for the determination of the peak temperature in the weld pool and provided a new method to estimate weld metal composition. Studies on the interfacial phenomena in fusion welding resulted in quantitative understanding of the interrelationship between the weld metal composition and geometry and provided new knowledge as to when the surface active elements would affect the weldment geometry and when these elements would have no effect on the geometry. Partitioning of oxygen nitrogen and hydrogen between the welding environment and the weld metal was affected by the extent of the dissociation of diatomic gaseous species which depended on the nature of the plasma formed during welding. The interfacial tension of the liquid metal was also affected by the plasma and the properties of the plasma affected the concentrations of oxygen, nitrogen and hydrogen in the weld metal. Apart from the understanding of the evolution of composition and geometry of the weldments, application of transport phenomena provided useful information about various features of the weldment structure. Quantitative understanding of microstructure of the fusion zone and heat

  5. Heterogeneous reactive transport under unsaturated transient conditions characterized by 3D electrical resistivity tomography and advanced lysimeter methods (United States)

    Wehrer, Markus; Slater, Lee


    Our ability to predict flow and transport processes in the unsaturated critical zone is considerably limited by two characteristics: heterogeneity of flow and transience of boundary conditions. The causes of heterogeneous flow and transport are fairly well understood, yet the characterization and quantification of such processes in natural profiles remains challenging. This is due to current methods of observation, such as staining and isotope tracers, being unable to observe multiple events on the same profile and offering limited spatial information. In our study we demonstrate an approach to characterize preferential flow and transport processes applying a combination of geoelectrical methods and advanced lysimeter techniques. On an agricultural soil profile, which was transferred undisturbed into a lysimeter container, we systematically applied a variety of input flow boundary conditions, resembling natural precipitation events. We measured breakthroughs of a conservative tracer and of nitrate, originating from the application of a slow release fertilizer and serving as a reactive tracer. Flow and transport in the soil column were observed using electrical resistivity tomography (ERT), tensiometers, water content probes and a multicompartment suction plate (MSP). These techniques allowed a direct validation of water content dynamics and tracer breakthrough under transient boundary conditions characterized noninvasively by ERT. We were able to image the advancing infiltration front and the advancing front of tracer and nitrate using time lapse ERT. Water content changes associated with the advancing infiltration front dominated over pore fluid conductivity changes during short term precipitation events. Conversely, long-term displacement of the solute fronts was monitored during periods of constant water content in between infiltration events. We observed preferential flow phenomena through ERT and through the MSP, which agreed in general terms. The preferential

  6. Correlated receptor transport processes buffer single-cell heterogeneity.

    Directory of Open Access Journals (Sweden)

    Stefan M Kallenberger


    Full Text Available Cells typically vary in their response to extracellular ligands. Receptor transport processes modulate ligand-receptor induced signal transduction and impact the variability in cellular responses. Here, we quantitatively characterized cellular variability in erythropoietin receptor (EpoR trafficking at the single-cell level based on live-cell imaging and mathematical modeling. Using ensembles of single-cell mathematical models reduced parameter uncertainties and showed that rapid EpoR turnover, transport of internalized EpoR back to the plasma membrane, and degradation of Epo-EpoR complexes were essential for receptor trafficking. EpoR trafficking dynamics in adherent H838 lung cancer cells closely resembled the dynamics previously characterized by mathematical modeling in suspension cells, indicating that dynamic properties of the EpoR system are widely conserved. Receptor transport processes differed by one order of magnitude between individual cells. However, the concentration of activated Epo-EpoR complexes was less variable due to the correlated kinetics of opposing transport processes acting as a buffering system.

  7. Examining the influence of heterogeneous porosity fields on conservative solute transport (United States)

    Hu, B.X.; Meerschaert, M.M.; Barrash, W.; Hyndman, D.W.; He, C.; Li, X.; Guo, Laodong


    It is widely recognized that groundwater flow and solute transport in natural media are largely controlled by heterogeneities. In the last three decades, many studies have examined the effects of heterogeneous hydraulic conductivity fields on flow and transport processes, but there has been much less attention to the influence of heterogeneous porosity fields. In this study, we use porosity and particle size measurements from boreholes at the Boise Hydrogeophysical Research Site (BHRS) to evaluate the importance of characterizing the spatial structure of porosity and grain size data for solute transport modeling. Then we develop synthetic hydraulic conductivity fields based on relatively simple measurements of porosity from borehole logs and grain size distributions from core samples to examine and compare the characteristics of tracer transport through these fields with and without inclusion of porosity heterogeneity. In particular, we develop horizontal 2D realizations based on data from one of the less heterogeneous units at the BHRS to examine effects where spatial variations in hydraulic parameters are not large. The results indicate that the distributions of porosity and the derived hydraulic conductivity in the study unit resemble fractal normal and lognormal fields respectively. We numerically simulate solute transport in stochastic fields and find that spatial variations in porosity have significant effects on the spread of an injected tracer plume including a significant delay in simulated tracer concentration histories.

  8. A continuous time random walk model for Darcy-scale anomalous transport in heterogeneous porous media. (United States)

    Comolli, Alessandro; Hakoun, Vivien; Dentz, Marco


    Achieving the understanding of the process of solute transport in heterogeneous porous media is of crucial importance for several environmental and social purposes, ranging from aquifers contamination and remediation, to risk assessment in nuclear waste repositories. The complexity of this aim is mainly ascribable to the heterogeneity of natural media, which can be observed at all the scales of interest, from pore scale to catchment scale. In fact, the intrinsic heterogeneity of porous media is responsible for the arising of the well-known non-Fickian footprints of transport, including heavy-tailed breakthrough curves, non-Gaussian spatial density profiles and the non-linear growth of the mean squared displacement. Several studies investigated the processes through which heterogeneity impacts the transport properties, which include local modifications to the advective-dispersive motion of solutes, mass exchanges between some mobile and immobile phases (e.g. sorption/desorption reactions or diffusion into solid matrix) and spatial correlation of the flow field. In the last decades, the continuous time random walk (CTRW) model has often been used to describe solute transport in heterogenous conditions and to quantify the impact of point heterogeneity, spatial correlation and mass transfer on the average transport properties [1]. Open issues regarding this approach are the possibility to relate measurable properties of the medium to the parameters of the model, as well as its capability to provide predictive information. In a recent work [2] the authors have shed new light on understanding the relationship between Lagrangian and Eulerian dynamics as well as on their evolution from arbitrary initial conditions. On the basis of these results, we derive a CTRW model for the description of Darcy-scale transport in d-dimensional media characterized by spatially random permeability fields. The CTRW approach models particle velocities as a spatial Markov process, which is

  9. Secure Media Independent Handover Message Transport in Heterogeneous Networks

    Directory of Open Access Journals (Sweden)

    Cho Choong-Ho


    Full Text Available The IEEE 802.21 framework for Media Independent Handover (MIH provides seamless vertical handover support for multimode mobile terminals. MIH messages are exchanged over various wireless media between mobile terminals and access networks to facilitate seamless handover. This calls for the need to secure MIH messages against network security threats in the wireless medium. In this paper, we first analyze IPSec/IKEv2 and DTLS security solution for secure MIH message transport. We show that handover latency can be an impediment to the use of IPSec and DTLS solutions. To overcome the handover overhead and hence minimize authentication time, a new secure MIH message transport solution, referred as MIHSec in this paper, is proposed. Experimental results are obtained for MIH between WLAN and Ethernet networks and the impacts of MIH message security on the handover latency are evaluated for IPSec, DTLS, and MIHSec security solutions. The effectiveness of MIHSec is demonstrated.

  10. Numerical study on micro-reformer performance and local transport phenomena of the plate methanol steam micro-reformer (United States)

    Hsueh, Ching-Yi; Chu, Hsin-Sen; Yan, Wei-Mon

    The objective of this work is to investigate the transport phenomena and performance of a plate steam methanol micro-reformer. Micro channels of various height and width ratios are numerically analyzed to understand their effects on the reactant gas transport characteristics and micro-reformer performance. In addition, influences of Reynolds number and geometric size of micro channel on methanol conversion of micro-reformer and gas transport phenomena are also explored. The predicted results demonstrated that better performance is noted for a micro channel reformer with lower aspect-ratio micro channel. This is due to the larger the chemical reaction surface area for a lower aspect-ratio channel reformer. It is also found that the methanol conversion decreases with increasing Reynolds number Re. The results also indicate that the smaller micro channel size experiences a better methanol conversion. This is due to the fact that a smaller micro channel has a much more uniform temperature distribution, which in turn, fuel utilization efficiency is improved for a smaller micro channel reformer.

  11. Intra-tumoral heterogeneity of gemcitabine delivery and mass transport in human pancreatic cancer (United States)

    Koay, Eugene J.; Baio, Flavio E.; Ondari, Alexander; Truty, Mark J.; Cristini, Vittorio; Thomas, Ryan M.; Chen, Rong; Chatterjee, Deyali; Kang, Ya’an; Zhang, Joy; Court, Laurence; Bhosale, Priya R.; Tamm, Eric P.; Qayyum, Aliya; Crane, Christopher H.; Javle, Milind; Katz, Matthew H.; Gottumukkala, Vijaya N.; Rozner, Marc A.; Shen, Haifa; Lee, Jeffrey E.; Wang, Huamin; Chen, Yuling; Plunkett, William; Abbruzzese, James L.; Wolff, Robert A.; Maitra, Anirban; Ferrari, Mauro; Varadhachary, Gauri R.; Fleming, Jason B.


    There is substantial heterogeneity in the clinical behavior of pancreatic cancer and in its response to therapy. Some of this variation may be due to differences in delivery of cytotoxic therapies between patients and within individual tumors. Indeed, in 12 patients with resectable pancreatic cancer, we previously demonstrated wide inter-patient variability in the delivery of gemcitabine as well as in the mass transport properties of tumors as measured by computed tomography (CT) scans. However, the variability of drug delivery and transport properties within pancreatic tumors is currently unknown. Here, we analyzed regional measurements of gemcitabine DNA incorporation in the tumors of the same 12 patients to understand the degree of intra-tumoral heterogeneity of drug delivery. We also developed a volumetric segmentation approach to measure mass transport properties from the CT scans of these patients and tested inter-observer agreement with this new methodology. Our results demonstrate significant heterogeneity of gemcitabine delivery within individual pancreatic tumors and across the patient cohort, with gemcitabine DNA incorporation in the inner portion of the tumors ranging from 38 to 74% of the total. Similarly, the CT-derived mass transport properties of the tumors had a high degree of heterogeneity, ranging from minimal difference to almost 200% difference between inner and outer portions of the tumor. Our quantitative method to derive transport properties from CT scans demonstrated less than 5% difference in gemcitabine prediction at the average CT-derived transport value across observers. These data illustrate significant inter-patient and intra-tumoral heterogeneity in the delivery of gemcitabine, and highlight how this variability can be reproducibly accounted for using principles of mass transport. With further validation as a biophysical marker, transport properties of tumors may be useful in patient selection for therapy and prediction of

  12. Intra-tumoral heterogeneity of gemcitabine delivery and mass transport in human pancreatic cancer (United States)

    Koay, Eugene J.; Baio, Flavio E.; Ondari, Alexander; Truty, Mark J.; Cristini, Vittorio; Thomas, Ryan M.; Chen, Rong; Chatterjee, Deyali; Kang, Ya'an; Zhang, Joy; Court, Laurence; Bhosale, Priya R.; Tamm, Eric P.; Qayyum, Aliya; Crane, Christopher H.; Javle, Milind; Katz, Matthew H.; Gottumukkala, Vijaya N.; Rozner, Marc A.; Shen, Haifa; Lee, Jeffrey E.; Wang, Huamin; Chen, Yuling; Plunkett, William; Abbruzzese, James L.; Wolff, Robert A.; Maitra, Anirban; Ferrari, Mauro; Varadhachary, Gauri R.; Fleming, Jason B.


    There is substantial heterogeneity in the clinical behavior of pancreatic cancer and in its response to therapy. Some of this variation may be due to differences in delivery of cytotoxic therapies between patients and within individual tumors. Indeed, in 12 patients with resectable pancreatic cancer, we previously demonstrated wide inter-patient variability in the delivery of gemcitabine as well as in the mass transport properties of tumors as measured by computed tomography (CT) scans. However, the variability of drug delivery and transport properties within pancreatic tumors is currently unknown. Here, we analyzed regional measurements of gemcitabine DNA incorporation in the tumors of the same 12 patients to understand the degree of intra-tumoral heterogeneity of drug delivery. We also developed a volumetric segmentation approach to measure mass transport properties from the CT scans of these patients and tested inter-observer agreement with this new methodology. Our results demonstrate significant heterogeneity of gemcitabine delivery within individual pancreatic tumors and across the patient cohort, with gemcitabine DNA incorporation in the inner portion of the tumors ranging from 38 to 74% of the total. Similarly, the CT-derived mass transport properties of the tumors had a high degree of heterogeneity, ranging from minimal difference to almost 200% difference between inner and outer portions of the tumor. Our quantitative method to derive transport properties from CT scans demonstrated less than 5% difference in gemcitabine prediction at the average CT-derived transport value across observers. These data illustrate significant inter-patient and intra-tumoral heterogeneity in the delivery of gemcitabine, and highlight how this variability can be reproducibly accounted for using principles of mass transport. With further validation as a biophysical marker, transport properties of tumors may be useful in patient selection for therapy and prediction of

  13. Transport phenomena in intracellular calcium dynamics driven by non-Gaussian noises (United States)

    Lin, Ling; Duan, Wei-Long


    The role of non-Gaussian noises on transport characteristic of Ca2+ in intracellular calcium oscillation system driven by non-Gaussian noises is studied by means of second-order stochastic Runge-Kutta type algorithm. The statistical properties of velocity of cytosolic and calcium store's Ca2+ concentration are simulated. The results exhibit, as parameter p(which is used to control the degree of the departure from the non-Gaussian noise and Gaussian noise.)increases, calcium in cytosol shows positive, zero, and negative transport, but in calcium store always hold positive value. As non-Gaussian noises increase, calcium in cytosol appears negative and zero transport, and in calcium store appears positive transport. As correlation time of non-Gaussian noises varies, calcium in both cytosol and calcium store occur negative, zero, and positive transport.

  14. Fast transient transport phenomena measured by soft X-ray emission in TCV tokamak plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Furno, I. [Ecole Polytechnique Federale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), CH-1015 Lausanne (Switzerland)


    Energy and particle transport during sawtooth activity in TCV plasmas has been studied in this thesis with high temporal resolution many chord diagnostics. We indicated the influence of sawteeth on plasma profiles in ohmic conditions and in the presence of auxiliary electron cyclotron resonance heating and current drive. A 2-dimensional model for heat transport, including localised heat source and a magnetic island, has been used to interpret the experimental observations. These results provided a new interpretation of a coupled heat and transport phenomenon which is potentially important for plasma confinement. The observations validate the applicability and show the possibility of improvement of a 2-dimensional theoretic a1 model for the study of heat transport in the presence of localised heat source and a magnetic island. Furthermore, the TCV results showed a new possibility for the interpretation of a coupled heat and particle transport phenomenon previously understood only in stellarators. (author)

  15. Interaction between breaking/broken waves and infragravity-scale phenomena to control sediment suspension transport in the surf zone

    CSIR Research Space (South Africa)

    Smith, GG


    Full Text Available 0025-3227 / 02 / $ ^ see front matter C223 2002 Elsevier Science B.V. All rights reserved. PII: S0025-3227(02)00385-7 * Corresponding author. E-mail address: (G.G. Smith). MARGO 3183 24-7-02 Marine Geology 187 (2002) 329^345 www....G. Smith, G.P. Mocke/ Marine Geology 187 (2002) 329^345 wave breaking processes, which interact with in- fragravity motions. Possible examples of the inter- action of wave breaking and infragravity sediment suspension and transport phenomena are (1) more...


    Energy Technology Data Exchange (ETDEWEB)

    Alex J. Dragt


    Since 1980, under the grant DEFG02-96ER40949, the Department of Energy has supported the educational and research work of the University of Maryland Dynamical Systems and Accelerator Theory (DSAT) Group. The primary focus of this educational/research group has been on the computation and analysis of charged-particle beam transport using Lie algebraic methods, and on advanced methods for the computation of electromagnetic fields and multiparticle phenomena. This Final Report summarizes the accomplishments of the DSAT Group from its inception in 1980 through its end in 2011.

  17. Experimental and analytical study of interfacial area transport phenomena in a vertical two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Byung-Gil; Euh, Dong-Jin; Yun, Byong-Jo; Youn, Young-Jung; Yoon, Han-Yeong; Song, Chul-Hwa


    The number density transport equations for various bubble groups are used to predict the void fraction and the interfacial area concentration. As the closure relations for number density transport equation, the coalescence due to random collisions and the breakup due to the impact of turbulent eddies is modified based on the previous studies and the bubble expansion term due to the pressure reduction is considered. Also, the coalescence due to a wake entrainment is modeled newly to apply to the number density transport equation. In order to predict the local experimental data, the code is developed that the two-fluid model is coupled systematically with the number density transport equation for each bubble group. As for the results of the numerical analysis, the void fraction and interfacial area concentration are predicted well by the developed code and models although some deviations exist in the values between the prediction and experiment, especially, for the high void fraction conditions.

  18. Mathematical interpretation of Brownian motor model: Limit cycles and directed transport phenomena (United States)

    Yang, Jianqiang; Ma, Hong; Zhong, Suchuang


    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.

  19. Spin Chirality and Hall-Like Transport Phenomena of Spin Excitations (United States)

    Han, Jung Hoon; Lee, Hyunyong


    Experimental and theoretical aspects of Hall-type transport of spins in magnetic insulators are reviewed. A general formalism for linear response theory of thermal Hall transport in the spin model is developed, which is general enough to be applicable to both the magnon and the paramagnetic, spin-liquid regimes. The expression of the energy current operator in the spin language is shown to be closely related to the spin chirality operator. Recent experiments on magnon-mediated thermal Hall transport in the two-dimensional kagome, and three-dimensional pyrochlore ferromagnetic insulators are reviewed in light of the multi-band magnon theory of Hall transport, and compared to the more mysterious thermal Hall transport found in the putative quantum spin ice material. As realizations of spin-chirality driven magnon transport in the real space, we review the general theory of emergent gauge fields governing the magnon dynamics in the textured magnet, and discuss its application to the magnon-Skyrmion scattering problem. Topological magnon Hall effect driven by the Skyrmion texture is discussed.

  20. Experimental investigation of transport phenomena in the scrape-off layer and divertor

    Energy Technology Data Exchange (ETDEWEB)

    LaBombard, B.; Goetz, J.A.; Hutchinson, I.; Jablonski, D.; Kesner, J.; Kurz, C.; Lipschultz, B.; McCracken, G.M.; Niemczewski, A.; Terry, J.; Allen, A.; Boivin, R.L.; Bombarda, F.; Bonoli, P.; Christensen, C.; Fiore, C.; Garnier, D.; Golovato, S.; Granetz, R.; Greenwald, M.; Horne, S.; Hubbard, A.; Irby, J.; Lo, D.; Lumma, D.; Marmar, E.; May, M.; Mazurenko, A.; Nachtrieb, R.; Ohkawa, H.; O`Shea, P.; Porkolab, M.; Reardon, J.; Rice, J.; Rost, J.; Schachter, J.; Snipes, J.; Sorci, J.; Stek, P.; Takase, Y.; Wang, Y.; Watterson, R.; Weaver, J.; Welch, B.; Wolfe, S. [Massachusetts Inst. of Technol., Cambridge (United States). Plasma Fusion Center]|[Associazione Euratom-ENEA sulla Fusione, Frascati (Italy)]|[Johns Hopkins University, Baltimore, MD (United States)]|[University of Maryland, College Park, MD (United States)


    Transport physics in the divertor and scrape-off layer of Alcator C-Mod is investigated for a wide range of plasma conditions. Parallel (parallel) transport topics include: low recycling, high-recycling, and detached regimes, thermoelectric currents, asymmetric heat fluxes driven by thermoelectric currents, and reversed divertor flows. Perpendicular (perpendicular to) transport topics include: expected and measured scalings of perpendicular to gradients with local conditions, estimated {chi} {sub perpendicular} {sub to} profiles and scalings, divertor neutral retention effects, and L-mode/H-mode effects. Key results are: (i) classical parallel transport is obeyed with ion-neutral momentum coupling effects, (ii) perpendicular to heat transport is proportional to local gradients, (iii) {chi} {sub perpendicular} {sub to} {proportional_to}T{sub e}{sup -0.6} n{sup -0.6} L{sup -0.7} in L-mode, insensitive to toroidal field, (iv) {chi} {sub perpendicular} {sub to} is dependent on divertor neutral retention, (v) H-mode transport barrier effects partially extend inside the SOL, (vi) inside/outside divertor asymmetries may be caused by a thermoelectric instability, and (vii) reversed parallel flows depend on divertor asymmetries and their implicit ionization source imbalances. (orig.).

  1. Modeling of the Transport Phenomena in Passive Direct Methanol Fuel Cells Using a Two-Phase Anisotropic Model

    Directory of Open Access Journals (Sweden)

    Zheng Miao


    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.

  2. The effects of physical and geochemical heterogeneities on hydro-geochemical transport and effective reaction rates (United States)

    Atchley, Adam L.; Navarre-Sitchler, Alexis K.; Maxwell, Reed M.


    The role of coupled physical and geochemical heterogeneities in hydro-geochemical transport is investigated by simulating three-dimensional transport in a heterogeneous system with kinetic mineral reactions. Ensembles of 100 physically heterogeneous realizations were simulated for three geochemical conditions: 1) spatially homogeneous reactive mineral surface area, 2) reactive surface area positively correlated to hydraulic heterogeneity, and 3) reactive surface area negatively correlated to hydraulic heterogeneity. Groundwater chemistry and the corresponding effective reaction rates were calculated at three transverse planes to quantify differences in plume evolution due to heterogeneity in mineral reaction rates and solute residence time (τ). The model is based on a hypothetical CO2 intrusion into groundwater from a carbon capture utilization and storage (CCUS) operation where CO2 dissolution and formation of carbonic acid created geochemical dis-equilibrium between fluids and the mineral galena that resulted in increased aqueous lead (Pb2 +) concentrations. Calcite dissolution buffered the pH change and created conditions of galena oversaturation, which then reduced lead concentrations along the flow path. Near the leak kinetic geochemical reactions control the release of solutes into the fluid, but further along the flow path mineral solubility controls solute concentrations. Simulation results demonstrate the impact of heterogeneous distribution of geochemical reactive surface area in coordination with physical heterogeneity on the effective reaction rate (Krxn,eff) and Pb2 + concentrations within the plume. Dissimilarities between ensemble Pb2 + concentration and Krxn,eff are attributed to how geochemical heterogeneity affects the time (τeq) and therefore advection distance (Leq) required for the system to re-establish geochemical equilibrium. Only after geochemical equilibrium is re-established, Krxn,eff and Pb2 + concentrations are the same for all three

  3. The effects of physical and geochemical heterogeneities on hydro-geochemical transport and effective reaction rates. (United States)

    Atchley, Adam L; Navarre-Sitchler, Alexis K; Maxwell, Reed M


    The role of coupled physical and geochemical heterogeneities in hydro-geochemical transport is investigated by simulating three-dimensional transport in a heterogeneous system with kinetic mineral reactions. Ensembles of 100 physically heterogeneous realizations were simulated for three geochemical conditions: 1) spatially homogeneous reactive mineral surface area, 2) reactive surface area positively correlated to hydraulic heterogeneity, and 3) reactive surface area negatively correlated to hydraulic heterogeneity. Groundwater chemistry and the corresponding effective reaction rates were calculated at three transverse planes to quantify differences in plume evolution due to heterogeneity in mineral reaction rates and solute residence time (τ). The model is based on a hypothetical CO2 intrusion into groundwater from a carbon capture utilization and storage (CCUS) operation where CO2 dissolution and formation of carbonic acid created geochemical dis-equilibrium between fluids and the mineral galena that resulted in increased aqueous lead (Pb(2+)) concentrations. Calcite dissolution buffered the pH change and created conditions of galena oversaturation, which then reduced lead concentrations along the flow path. Near the leak kinetic geochemical reactions control the release of solutes into the fluid, but further along the flow path mineral solubility controls solute concentrations. Simulation results demonstrate the impact of heterogeneous distribution of geochemical reactive surface area in coordination with physical heterogeneity on the effective reaction rate (Krxn,eff) and Pb(2+) concentrations within the plume. Dissimilarities between ensemble Pb(2+) concentration and Krxn,eff are attributed to how geochemical heterogeneity affects the time (τeq) and therefore advection distance (Leq) required for the system to re-establish geochemical equilibrium. Only after geochemical equilibrium is re-established, Krxn,eff and Pb(2+) concentrations are the same for all

  4. Compositional multiphase flow and transport in heterogeneous porous media

    Energy Technology Data Exchange (ETDEWEB)

    Huber, R.U.


    This work first treats the conceptual models for the description of multiphase flow processes in porous media. The thermodynamic laws are explained and the description and quantification of multi-fluid equilibria are discussed in order to account for fluid composition. The fully and weakly coupled approaches for the mathematical description of such flow processes with respect to systems consisting of two and three fluid phases as well as with respect to compositional single and multiphase systems are assessed. For the discretization of the two-phase flow equations node- and cell-centered finite volume methods and mixed and mixed-hybrid finite element approaches are applied. Based upon these methods five solution algorithms are developed. Four of these algorithms are based on the simultaneous solution of the discretized equations in combination with the Newton-Raphson technique. Methods 1 and 2 treat two- three-phase flow processes, Method 3 applies to the solution of partially miscible three-component systems while Method 4 is created for three-phase three-component systems. The latter method uses a variable substitution dependent on the local presence of the fluid phases. Method 5 is based on the IMPES/IMPESC concept. The time-implicit pressure equation is discretized with the mixed-hybrid finite element method. The saturation and concentration equations, respectively, are solved with a cell-centered finite volume scheme. The developed algorithms are applied to the two- and three-phase Buckley-Leverett problems. A partitioning interwell tracer test is simulated. The propagation behavior of nonaqueous phase liquids (NAPLs) in the saturated and unsaturated ground zone under the influence of heterogeneities are examined. In addition, a larger-scale experiment is simulated, which involves an injection of trichloroethylene into the subsurface and the subsequent distribution. Here, the development of a dissolved contaminant plume as well as the behavior of organic

  5. Thermodynamics, transport phenomena, and electrochemistry of external field-assisted nonthermal food technologies. (United States)

    Misra, N N; Martynenko, Alex; Chemat, Farid; Paniwnyk, Larysa; Barba, Francisco J; Jambrak, Anet Režek


    Interest in the development and adoption of nonthermal technologies is burgeoning within the food and bioprocess industry, the associated research community, and among the consumers. This is evident from not only the success of some innovative nonthermal technologies at industrial scale, but also from the increasing number of publications dealing with these topics, a growing demand for foods processed by nonthermal technologies and use of natural ingredients. A notable feature of the nonthermal technologies such as cold plasma, electrohydrodynamic processing, pulsed electric fields, and ultrasound is the involvement of external fields, either electric or sound. Therefore, it merits to study the fundamentals of these technologies and the associated phenomenon with a unified approach. In this review, we revisit the fundamental physical and chemical phenomena governing the selected technologies, highlight similarities, and contrasts, describe few successful applications, and finally, identify the gaps in research.

  6. Electron transport and spin phenomena in hybrid organic/inorganic systems

    NARCIS (Netherlands)

    Naber, W.J.M.


    This thesis describes several experiments in hybrid organic/inorganic systems, in which electron transport and/or spin behavior is studied. The basic concepts of organic electronics and spintronics are given, to understand the described spin-valve experiments. The problems and obstacles for

  7. Correlating Humidity-Dependent Ionically Conductive Surface Area with Transport Phenomena in Proton-Exchange Membranes

    Energy Technology Data Exchange (ETDEWEB)

    He, Qinggang; Kusoglu, Ahmet; Lucas, Ivan T.; Clark, Kyle; Weber, Adam Z.; Kostecki, Robert


    The objective of this effort was to correlate the local surface ionic conductance of a Nafion? 212 proton-exchange membrane with its bulk and interfacial transport properties as a function of water content. Both macroscopic and microscopic proton conductivities were investigated at different relative humidity levels, using electrochemical impedance spectroscopy and current-sensing atomic force microscopy (CSAFM). We were able to identify small ion-conducting domains that grew with humidity at the surface of the membrane. Numerical analysis of the surface ionic conductance images recorded at various relative humidity levels helped determine the fractional area of ion-conducting active sites. A simple square-root relationship between the fractional conducting area and observed interfacial mass-transport resistance was established. Furthermore, the relationship between the bulk ionic conductivity and surface ionic conductance pattern of the Nafion? membrane was examined.

  8. Correlating humidity-dependent ionically conductive surface area with transport phenomena in proton-exchange membranes. (United States)

    He, Qinggang; Kusoglu, Ahmet; Lucas, Ivan T; Clark, Kyle; Weber, Adam Z; Kostecki, Robert


    The objective of this effort was to correlate the local surface ionic conductance of a Nafion 212 proton-exchange membrane with its bulk and interfacial transport properties as a function of water content. Both macroscopic and microscopic proton conductivities were investigated at different relative humidity levels, using direct-current voltammetry and current-sensing atomic force microscopy (CSAFM). We were able to identify small ion-conducting domains that grew with humidity at the surface of the membrane. Numerical analysis of the surface ionic conductance images recorded at various relative humidity levels helped determine the fractional area of ion-conducting active sites. A simple square-root relationship between the fractional conducting area and observed interfacial mass-transport resistance was established. Furthermore, the relationship between the bulk ionic conductivity and surface ionic conductance pattern of the Nafion membrane was examined.

  9. Continuous-time random-walk model of transport in variably saturated heterogeneous porous media. (United States)

    Zoia, Andrea; Néel, Marie-Christine; Cortis, Andrea


    We propose a unified physical framework for transport in variably saturated porous media. This approach allows fluid flow and solute migration to be treated as ensemble averages of fluid and solute particles, respectively. We consider the cases of homogeneous and heterogeneous porous materials. Within a fractal mobile-immobile continuous time random-walk framework, the heterogeneity will be characterized by algebraically decaying particle retention times. We derive the corresponding (nonlinear) continuum-limit partial differential equations and we compare their solutions to Monte Carlo simulation results. The proposed methodology is fairly general and can be used to track fluid and solutes particles trajectories for a variety of initial and boundary conditions.

  10. Dynamics of a Transportation Network Model with Homogeneous and Heterogeneous Users

    Directory of Open Access Journals (Sweden)

    Yingguo Li


    Full Text Available This paper studies the dynamics of the traveler's day-to-day route adjustment process in the general transportation network with fixed or elastic demand and homogeneous or heterogeneous users. Each traveler is assumed to adjust his/her route choice according to the excess travel cost between the instantaneous experienced travel cost and a certain referred level, which induces an aggregate path flow dynamics. We call the path flow dynamics the excess travel cost dynamics, which corresponds to the excess payoff dynamics in evolutionary games and serves a general framework of modeling the homogeneous or heterogeneous route choice behavior of travelers.

  11. An Equation-Type Approach for the Numerical Solution of the Partial Differential Equations Governing Transport Phenomena in Porous Media

    KAUST Repository

    Sun, Shuyu


    A new technique for the numerical solution of the partial differential equations governing transport phenomena in porous media is introduced. In this technique, the governing equations as depicted from the physics of the problem are used without extra manipulations. In other words, there is no need to reduce the number of governing equations by some sort of mathematical manipulations. This technique enables the separation of the physics part of the problem and the solver part, which makes coding more robust and could be used in several other applications with little or no modifications (e.g., multi-phase flow in porous media). In this method, one abandons the need to construct the coefficient matrix for the pressure equation. Alternatively, the coefficients are automatically generated within the solver routine. We show examples of using this technique to solving several flow problems in porous media.

  12. Initiation and modification of reaction by energy addition: Kinetic and transport phenomena (United States)

    Fendell, Francis E.; Chou, Mau-Song


    Work has been pursued, by application of the fundamental principles of chemical kinetics and fluid transport, on a 'proof-of-principle' for a novel oblique-detonation-wave-engine (ODWE) as an alternative to a mixing-controlled supersonic combustor. The concept involves the nonintrusive stabilization of a conical detonation wave. Laser technology permits the rapidly repeated pulsed deposition of energy at a fixed site on the axis of symmetry of a supersonically flowing, combustible mixture. Each pulse suffices for the direct initiation of a radially-, outwardly-propagating, Chapman-Jouguet detonation wave. The interaction of the individual spherical waves, as the periodic train is convected by the flow, results in a nonintrusively stabilized conical wave as the time interval between the very brief pulses decreases. The detonated gas may be expanded in a supersonic nozzle (of practical length) for discharge at ambient pressure, such that thrust is generated.

  13. Investigation of high-p{sub T} phenomena within a partonic transport model

    Energy Technology Data Exchange (ETDEWEB)

    Fochler, Oliver


    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.)

  14. Solute transport in a heterogeneous aquifer: a search for nonlinear deterministic dynamics

    Directory of Open Access Journals (Sweden)

    B. Sivakumar


    Full Text Available The potential use of a nonlinear deterministic framework for understanding the dynamic nature of solute transport processes in subsurface formations is investigated. Time series of solute particle transport in a heterogeneous aquifer medium, simulated using an integrated probability/Markov chain (TP/MC model, groundwater flow model, and particle transport model, are studied. The correlation dimension method, a popular nonlinear time series analysis technique, is used to identify nonlinear determinism. Sensitivity of the solute transport dynamics to the four hydrostratigraphic parameters involved in the TP/MC model: (1 number of facies; (2 volume proportions of facies; (3 mean lengths (and thereby anisotropy ratio of mean length of facies; and (4 juxtapositional tendencies (i.e. degree of entropy among the facies is also studied. The western San Joaquin Valley aquifer system in California is considered as a reference system. The results indicate, in general, the nonlinear deterministic nature of solute transport dynamics (dominantly governed by only a very few variables, on the order of 3, even though more complex behavior is possible under certain (extreme hydrostratigraphic conditions. The sensitivity analysis reveals: (1 the importance of the hydrostratigraphic parameters (in particular, volume proportions of facies and mean lengths in representing aquifer heterogeneity; and (2 the ability of the correlation dimension method in capturing the (extent of complexity of the underlying dynamics. Verification and confirmation of the present results through use of other nonlinear deterministic techniques and assessment of their reliability for a wide range of solute transport scenarios are recommended.

  15. Modeling of transport phenomena during gas hydrate decomposition by depressurization and/or thermal stimulation (United States)

    Abendroth*, Sven; Klump, Jens; Thaler, Jan; Schicks, Judith M.


    In the context of the German joint project SUGAR (Submarine Gas Hydrate Reservoirs: exploration, extraction and transport) we conducted a series of experiments in the LArge Reservoir Simulator (LARS) at the German Research Centre of Geosciences Potsdam (Beeskow-Strauch et al., this volume). These experiments allow us to investigate the formation and dissociation of hydrates at large scale laboratory conditions. Processes inside LARS are modeled to study the effects of sediment properties as well as physical and chemical processes on parameters such as hydrate dissociation rate and methane production rate. The experimental results from LARS are used to provide details about processes inside the pressure vessel, validate the models through history matching, and feed back into the design of future experiments. In experiments in LARS the amount of methane produced from gas hydrates was much lower than expected. Previously published models predict a methane production rate higher than the observed in experiments and field studies (Uddin and Wright 2005; Uddin et al. 2010; Wright et al. 2011). The authors of the aforementioned studies point out that the current modeling approach overestimates the gas production rate when modeling gas production by depressurization. Uddin and Wright (2005) suggested that trapping of gas bubbles inside the porous medium is responsible for the reduced gas production rate. They point out that this behavior of multi-phase flow is not well explained by a "residual oil" model, but rather resembles a "foamy oil" model. Our study applies Uddin's (2010) "foamy oil" model and combines it with history matches of our experiments in LARS. First results indicate a better agreement between experimental and model results when using the "foamy oil" model instead of conventional models featuring gas flow in water. Further experiments with LARS, including hydrate dissociation by depressurization and thermal stimulation by in-situ combustion will be used to

  16. Predicting Upscaling Relationships for Heterogeneous Flow and Reactive Transport at the Savannah River Site (United States)

    Arora, B.; Wainwright, H. M.; Spycher, N.


    This study aims at understanding key hydrogeochemical processes dictating pH behavior and U transport at the Savannah River Site (SRS) F-Area, South Carolina, with particular focus on the impact of chemical and physical heterogeneities. Acidic waste solutions containing low level radioactivity from numerous isotopes were discharged to a series of unlined seepage basins at the F-Area, from 1955 through 1989, which resulted in a nearly 1 km long acidic uranium plume. Reactive facies is a new approach that spatially characterizes linked flow and geochemical properties over large domains, where it is typically challenging to obtain parameters with sufficient resolution for reactive transport modeling. This approach - based on the hypothesis that we can identify geological units that have unique distributions of reactive transport properties - allows us to integrate various types of datasets (e.g., historical data, laboratory analysis, crosshole and surface geophysics) for estimating heterogeneous reactive transport parameters. At the SRS F-Area, data mining and iteration with laboratory analysis identified two reactive facies coincident with the depositional facies, which have distinct distributions of reactive transport properties: %fines, permeability, and Al:Fe ratio (proxy for kaolinite:geothite ratio). The reactive facies over the plume-scale domain was estimated based on measured data (foot-by-foot core analysis, cone penetrometer, crosshole seismic and surface seismic data) and integrated using the Bayesian framework. In parallel, a numerical reactive transport model was developed including saturated and unsaturated flow, and complex geochemical processes such as U(VI) and H+ adsorption (surface complexation) onto sediments and dissolution and precipitation of Al and Fe minerals. By combining the developed reactive transport model with the estimated spatial distribution of reactive transport parameters, we perform stochastic simulations of U and pH plume

  17. Effects of incomplete mixing on reactive transport in flows through heterogeneous porous media (United States)

    Wright, Elise E.; Richter, David H.; Bolster, Diogo


    The phenomenon of incomplete mixing reduces bulk effective reaction rates in reactive transport. Many existing models do not account for these effects, resulting in the overestimation of reaction rates in laboratory and field settings. To date, most studies on incomplete mixing have focused on diffusive systems; here, we extend these to explore the role that flow heterogeneity has on incomplete mixing. To do this, we examine reactive transport using a Lagrangian reactive particle tracking algorithm in two-dimensional idealized heterogeneous porous media. Contingent on the nondimensional Peclet and Damköhler numbers in the system, it was found that near well-mixed behavior could be observed at late times in the heterogeneous flow field simulations. We look at three common flow deformation metrics that describe the enhancement of mixing in the flow due to velocity gradients: the Okubo-Weiss parameter (θ ), the largest eigenvalue of the Cauchy-Green strain tensor (λC), and the finite-time Lyapunov exponent (Λ ). Strong mixing regions in the heterogeneous flow field identified by these metrics were found to correspond to regions with higher numbers of reactions, but the infrequency of these regions compared to the large numbers of reactions occurring elsewhere in the domain imply that these strong mixing regions are insufficient in explaining the observed near well-mixed behavior. Since it was found that reactive transport in these heterogeneous flows could overcome the effects of incomplete mixing, we also search for a closure for the mean concentration. The conservative quantity u2¯, where u =CA-CB , was found to predict the late time scaling of the mean concentration, i.e., Ci¯˜u2¯ .

  18. Longitudinal dispersion coefficients for numerical modeling of groundwater solute transport in heterogeneous formations

    DEFF Research Database (Denmark)

    Lee, Jonghyun; Rolle, Massimo; Kitanidis, Peter K.


    such parameterization is by far the most commonly used in solute transport applications, its validity has been questioned. Here, our goal is to investigate the effects of heterogeneity and mass transfer limitations on block-scale longitudinal dispersion and to evaluate under which conditions the Scheidegger...... parameterization is valid. We compute the relaxation time or memory of the system; changes in time with periods larger than the relaxation time are gradually leading to a condition of local equilibrium under which dispersion is Fickian. The method we use requires the solution of a steady-state advection...... meaning of the method and we show how the block longitudinal dispersivity approaches, under certain conditions, the Scheidegger limit at large Péclet numbers. Lastly, we discuss the potential and limitations of the method to accurately describe dispersion in solute transport applications in heterogeneous...

  19. Investigation of chemical properties and transport phenomena associated with pollutants in the atmospheric boundary layer (United States)

    Holmes, Heather A.

    Under the Clean Air Act, the U.S. Environmental Protection Agency is required to determine which air pollutants are harmful to human health, then regulate, monitor and establish criteria levels for these pollutants. To accomplish this and for scientific advancement, integration of knowledge from several disciplines is required including: engineering, atmospheric science, chemistry and public health. Recently, a shift has been made to establish interdisciplinary research groups to better understand the atmospheric processes that govern the transport of pollutants and chemical reactions of species in the atmospheric boundary layer (ABL). The primary reason for interdisciplinary collaboration is the need for atmospheric processes to be treated as a coupled system, and to design experiments that measure meteorological, chemical and physical variables simultaneously so forecasting models can be improved (i.e., meteorological and chemical process models). This dissertation focuses on integrating research disciplines to provide a more complete framework to study pollutants in the ABL. For example, chemical characterization of particulate matter (PM) and the physical processes governing PM distribution and mixing are combined to provide more comprehensive data for source apportionment. Data from three field experiments were utilized to study turbulence, meteorological and chemical parameters in the ABL. Two air quality field studies were conducted on the U.S./Mexico border. The first was located in Yuma, AZ to investigate the spatial and temporal variability of PM in an urban environment and relate chemical properties of ambient aerosols to physical findings. The second border air quality study was conducted in Nogales, Sonora, Mexico to investigate the relationship between indoor and outdoor air quality in order to better correlate cooking fuel types and home activities to elevated indoor PM concentrations. The final study was executed in southern Idaho and focused on

  20. Mathematical Modeling of Transport Phenomena in Polymer Electrolyte and Direct Methanol Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Birgersson, Erik


    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

  1. Selective Fusion of Heterogeneous Classifiers for Predicting Substrates of Membrane Transporters. (United States)

    Shaikh, Naeem; Sharma, Mahesh; Garg, Prabha


    Membrane transporters play a crucial role in determining fate of administered drugs in a biological system. Early identification of plausible transporters for a drug molecule can provide insights into its therapeutic, pharmacokinetic, and toxicological profiles. In the present study, predictive models for classifying small molecules into substrates and nonsubstrates of various pharmaceutically important membrane transporters were developed using quantitative structure-activity relationship (QSAR) and proteochemometric (PCM) approaches. For this purpose, 4575 substrate interactions for these transporters were collected from the Metabolism and Transport Database (Metrabase) and the literature. The transporters selected for this study include (i) six efflux transporters, viz., breast cancer resistance protein (BCRP/ABCG2), P-glycoprotein (P-gp/MDR1), and multidrug resistance proteins (MRP1, MRP2, MRP3, and MRP4), and (ii) seven influx transporters, viz., organic cation transporter (OCT1/SO22A1), peptide transporter (PEPT1/SO15A1), apical sodium-bile acid transporter (ASBT/NTCP2), and organic anion transporting peptides (OATP1A2/SO1A2, OATP1B/SO1B1, OATP1B3/SO1B3, and OATP2B1/SO2B1). Various types of descriptors and machine learning methods (classifiers) were evaluated for the development of robust predictive models. Additionally, ensemble models were developed by bagging of homogeneous classifiers and selective fusion of heterogeneous classifiers. It was observed that the latter approach improves the accuracy of substrate/nonsubstrate prediction for transporters (average correct classification rate of more than 0.80 for external validation). Moreover, structural fragments important in determining the substrate specificity across the various transporters were identified. To demonstrate these fragments on the query molecule, contour maps were generated. The prediction efficacy of the developed models was illustrated by a good correlation between the reported logBB value

  2. Modeling of Flow, Transport and Controlled Sedimentation Phenomena during Mixing of Salt Solutions in Complex Porous Formations (United States)

    Skouras, Eugene D.; Jaho, Sofia; Pavlakou, Efstathia I.; Sygouni, Varvara; Petsi, Anastasia; Paraskeva, Christakis A.


    The deposition of salts in porous media is a major engineering phenomenon encountered in a plethora of industrial and environmental applications where in some cases is desirable and in other not (oil production, geothermal systems, soil stabilization etc). Systematic approach of these problems requires knowledge of the key mechanisms of precipitating salts within the porous structures, in order to develop new methods to control the process. In this work, the development and the solution of spatiotemporally variable mass balances during salt solution mixing along specific pores were performed. Both analytical models and finite differences CFD models were applied for the study of flow and transport with simultaneous homogeneous and heterogeneous nucleation (by crystal growth on the surface of the pores) in simple geometries, while unstructured finite elements and meshless methods were developed and implemented for spatial discretization, reconstruction, and solution of transport equations and homogeneous / heterogeneous reactions in more complex geometries. At initial stages of this work, critical problem parameters were identified, such as the characteristics of the porosity, the number of dissolved components, etc. The parameters were then used for solving problems which correspond to available experimental data. For each combination of ions and materials, specific data and process characteristics were included: (a) crystal kinetics (nucleation, growth rates or reaction surface rates of crystals, critical suspension concentrations), (b) physico-chemical properties (bulk density, dimensions of generated crystals, ion diffusion coefficients in the solution), (c) operating parameters (macroscopic velocity, flow, or pressure gradient of the solution, ion concentration) (d) microfluidic data (geometry, flow area), (e) porosity data in Darcy description (initial porosity, specific surface area, tortuosity). During the modeling of flow and transport in three

  3. A Comparison of Numerical Strategies for Modeling the Transport Phenomena in High-Energy Laser Surface Alloying Process

    Directory of Open Access Journals (Sweden)

    Dipankar Chatterjee


    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

  4. Stretched and Filtered Transport Precondititioning of Sn Problems Part 2: Heterogeneous Media

    Energy Technology Data Exchange (ETDEWEB)

    Hanshaw, H L; Nowak, P; Larsen, E W


    In [1], we presented the stretched filtered transport synthetic acceleration method (SFTSA) for homogeneous media. Both SFTSA and SFTSA preconditioned Krylov were shown to be effective iterative schemes in homogeneous media due to the predictable structure of the iteration eigenvalues. In heterogeneous media or on non-uniform grids, the eigenvalue structure is unpredictable for general problems, making the filter strength a for optimal SFTSA extremely problem dependent. Leaving Q set to the optimal value (in each cell by table lookup) predicted by homogeneous media theory can make SFTSA divergent, even for relatively mild heterogeneities. Thus, SFTSA is more fragile than DSA in the sense that most DSA schemes break down only for much more severe heterogeneities. Fortunately, breakdown of SFTSA occurs with large negative eigenvalues, and Krylov methods preconditioned with SFTSA remain effective for such problems. Therefore, with a Krylov scheme ''wrapped around'' SFTSA, the resulting method is relatively insensitive to the filter strength, and a user may achieve reasonably good performance, if not optimal, with a fixed a over a wide range of heterogeneous problems.

  5. Asymptotic modeling of transport phenomena at the interface between a fluid and a porous layer: Jump conditions (United States)

    Angot, Philippe; Goyeau, Benoît; Ochoa-Tapia, J. Alberto


    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 .

  6. Analysis of Flow and Transport in non-Gaussian Heterogeneous Formations Using a Generalized Sub-Gaussian Model (United States)

    Guadagnini, A.; Riva, M.; Neuman, S. P.


    Environmental quantities such as log hydraulic conductivity (or transmissivity), Y(x) = ln K(x), and their spatial (or temporal) increments, ΔY, are known to be generally non-Gaussian. Documented evidence of such behavior includes symmetry of increment distributions at all separation scales (or lags) between incremental values of Y with sharp peaks and heavy tails that decay asymptotically as lag increases. This statistical scaling occurs in porous as well as fractured media characterized by either one or a hierarchy of spatial correlation scales. In hierarchical media one observes a range of additional statistical ΔY scaling phenomena, all of which are captured comprehensibly by a novel generalized sub-Gaussian (GSG) model. In this model Y forms a mixture Y(x) = U(x) G(x) of single- or multi-scale Gaussian processes G having random variances, U being a non-negative subordinator independent of G. Elsewhere we developed ways to generate unconditional and conditional random realizations of isotropic or anisotropic GSG fields which can be embedded in numerical Monte Carlo flow and transport simulations. Here we present and discuss expressions for probability distribution functions of Y and ΔY as well as their lead statistical moments. We then focus on a simple flow setting of mean uniform steady state flow in an unbounded, two-dimensional domain, exploring ways in which non-Gaussian heterogeneity affects stochastic flow and transport descriptions. Our expressions represent (a) lead order autocovariance and cross-covariance functions of hydraulic head, velocity and advective particle displacement as well as (b) analogues of preasymptotic and asymptotic Fickian dispersion coefficients. We compare them with corresponding expressions developed in the literature for Gaussian Y.

  7. Liquid Structure with Nano-Heterogeneity Promotes Cationic Transport in Concentrated Electrolytes. (United States)

    Borodin, Oleg; Suo, Liumin; Gobet, Mallory; Ren, Xiaoming; Wang, Fei; Faraone, Antonio; Peng, Jing; Olguin, Marco; Schroeder, Marshall; Ding, Michael S; Gobrogge, Eric; von Wald Cresce, Arthur; Munoz, Stephen; Dura, Joseph A; Greenbaum, Steve; Wang, Chunsheng; Xu, Kang


    Using molecular dynamics simulations, small-angle neutron scattering, and a variety of spectroscopic techniques, we evaluated the ion solvation and transport behaviors in aqueous electrolytes containing bis(trifluoromethanesulfonyl)imide. We discovered that, at high salt concentrations (from 10 to 21 mol/kg), a disproportion of cation solvation occurs, leading to a liquid structure of heterogeneous domains with a characteristic length scale of 1 to 2 nm. This unusual nano-heterogeneity effectively decouples cations from the Coulombic traps of anions and provides a 3D percolating lithium-water network, via which 40% of the lithium cations are liberated for fast ion transport even in concentration ranges traditionally considered too viscous. Due to such percolation networks, superconcentrated aqueous electrolytes are characterized by a high lithium-transference number (0.73), which is key to supporting an assortment of battery chemistries at high rate. The in-depth understanding of this transport mechanism establishes guiding principles to the tailored design of future superconcentrated electrolyte systems.

  8. Influence of Tailored Applied Magnetic Fields on High-Power MPD Thruster Current Transport and Onset-Related Phenomena (United States)

    Moeller, Robert C.; Polk, James E.


    This work investigated the effects of tailored, externally-applied magnetic fields on current transport and near-anode processes in the plasma discharge of a magnetoplasmadynamic thruster (MPDT). Electrical and plasma diagnostics were used to investigate how localized applied magnetic fields could mitigate the effects of the "onset" phenomena, including large-amplitude terminal voltage fluctuations and high anode fall voltages associated with unstable operation and anode erosion. An MPDT with a multi-channel hollow cathode was developed and tested with quasi-steady pulses of 1 millisecond duration at power levels of 36 kilowatts (20 volts, 1800 amperes) to 3.3 milliwatts (255 volts, 13.1 kiloamperes) with argon propellant in three different magnetic configurations: self-field, applied B field tangential to the anode lip near the exit plane, and applied cusp B field. The current pattern and current densities redistributed to follow the applied poloidal magnetic field lines, which created increased conduction paths to the anode. Also, the anode fall voltage was substantially reduced with both applied B field topologies over a large range of currents. For example, at 10.7 kiloamperes, the cusp applied magnetic field decreased anode fall voltages from 45-83 volts down to 15 volts or lower along much of the anode. The amplitude and frequency of the voltage fluctuations were also reduced over a broad range of currents with the applied fields. E.g., the standard deviations of the fluctuations were lowered by 37-49 percent at 8-9 kiloamperes. In addition, decreases in the mean terminal voltages as large as 31 percent were measured with the applied magnetic fields. These effects are shown to be associated with the increased current conduction along the applied magnetic field lines in the near-anode region. These results also suggest a reduction in frequency and intensity of current-concentrating filaments and anode spots, which contribute to erosion. Overall, both applied

  9. Coulombic interactions and multicomponent ionic dispersion during transport of charged species in heterogeneous porous media

    DEFF Research Database (Denmark)

    Muniruzzaman, Muhammad; Rolle, Massimo

    the capability of the proposed two-dimensional multicomponent approach to describe transport of charged species and to accurately capture the Coulombic interactions between the ions, which are clearly observed in the flow-through experiments. Furthermore, the model allowed us to directly quantify and visualize...... the ionic interactions by mapping the Coulombic cross-coupling between the dispersive fluxes of the charged species in the heterogeneous domains. The outcomes of this study are important in many subsurface applications including migration of contaminants and propagation of reaction fronts....

  10. Paranormal phenomena (United States)

    Gaina, Alex


    Critical analysis is given of some paranormal phenomena events (UFO, healers, psychokinesis (telekinesis))reported in Moldova. It is argued that correct analysis of paranormal phenomena should be made in the framework of electromagnetism.

  11. Correlation of Capture Efficiency with the Geometry, Transport, and Reaction Parameters in Heterogeneous Immunosensors. (United States)

    Rath, Dharitri; Panda, Siddhartha


    Higher capture efficiency of biomarkers in heterogeneous immunosensors would enable early detection of diseases. Several strategies are used to improve the capture efficiency of these immunosensors including the geometry of the system along with the transport and reaction parameters. Having a prior knowledge of the behavior of the above parameters would facilitate the design of an efficient immunosensor. While the contributions of the transport and reaction parameters toward understanding of the mechanism involved in capture have been well studied in the literature, their effect in combination with the geometry of the sensors has not been explored until now. In this work, we have experimentally demonstrated that the capture efficiency of the antigen-antibody systems is inversely related to the size of the sensor patch. The experimental system was simulated in order to get an in-depth understanding of the mechanism behind the experimental observation. Further, the extent of heterogeneity in the system was analyzed using the Sips isotherm to obtain the heterogeneity index (α) and the reaction rate constant (K(D)) as fitted parameters for a sensor patch of 1.5 mm radius. The experimental kinetic data obtained for the same sensor patch matched reasonably with the simulation results by considering K(D) as the global affinity constant, which indicated that our system can be considered to be homogeneous. Our simulation results associated with the size dependency of the capture efficiency were in agreement with the trends obtained in our experimental observations where an inverse relation was observed owing to the fact that the mass-transfer limitation decreases with the decrease in the size of the sensor patch. The possible underlying mechanism associated with size dependency of capture efficiency was discussed based on the time-dependent radial variation of captured antigens obtained from our simulation results. A study on the parametric variation was further conducted

  12. Uncertainty estimation in one-dimensional heat transport model for heterogeneous porous medium. (United States)

    Chang, Ching-Min; Yeh, Hund-Der


    In many practical applications, the rates for ground water recharge and discharge are determined based on the analytical solution developed by Bredehoeft and Papadopulos (1965) to the one-dimensional steady-state heat transport equation. Groundwater flow processes are affected by the heterogeneity of subsurface systems; yet, the details of which cannot be anticipated precisely. There exists a great deal of uncertainty (variability) associated with the application of Bredehoeft and Papadopulos' solution (1965) to the field-scale heat transport problems. However, the quantification of uncertainty involved in such application has so far not been addressed, which is the objective of this wok. In addition, the influence of the statistical properties of log hydraulic conductivity field on the variability in temperature field in a heterogeneous aquifer is also investigated. The results of the analysis demonstrate that the variability (or uncertainty) in the temperature field increases with the correlation scale of the log hydraulic conductivity covariance function and the variability of temperature field also depends positively on the position. © 2013, National Ground Water Association.

  13. Space-time mesh adaptation for solute transport in randomly heterogeneous porous media. (United States)

    Dell'Oca, Aronne; Porta, Giovanni Michele; Guadagnini, Alberto; Riva, Monica


    We assess the impact of an anisotropic space and time grid adaptation technique on our ability to solve numerically solute transport in heterogeneous porous media. Heterogeneity is characterized in terms of the spatial distribution of hydraulic conductivity, whose natural logarithm, Y, is treated as a second-order stationary random process. We consider nonreactive transport of dissolved chemicals to be governed by an Advection Dispersion Equation at the continuum scale. The flow field, which provides the advective component of transport, is obtained through the numerical solution of Darcy's law. A suitable recovery-based error estimator is analyzed to guide the adaptive discretization. We investigate two diverse strategies guiding the (space-time) anisotropic mesh adaptation. These are respectively grounded on the definition of the guiding error estimator through the spatial gradients of: (i) the concentration field only; (ii) both concentration and velocity components. We test the approach for two-dimensional computational scenarios with moderate and high levels of heterogeneity, the latter being expressed in terms of the variance of Y. As quantities of interest, we key our analysis towards the time evolution of section-averaged and point-wise solute breakthrough curves, second centered spatial moment of concentration, and scalar dissipation rate. As a reference against which we test our results, we consider corresponding solutions associated with uniform space-time grids whose level of refinement is established through a detailed convergence study. We find a satisfactory comparison between results for the adaptive methodologies and such reference solutions, our adaptive technique being associated with a markedly reduced computational cost. Comparison of the two adaptive strategies tested suggests that: (i) defining the error estimator relying solely on concentration fields yields some advantages in grasping the key features of solute transport taking place within

  14. Modeling multicomponent ionic transport in groundwater with IPhreeqc coupling: Electrostatic interactions and geochemical reactions in homogeneous and heterogeneous domains

    DEFF Research Database (Denmark)

    Muniruzzaman, Muhammad; Rolle, Massimo


    the electrostatic interactions during transport of charged ions in physically and chemically heterogeneous porous media. The modeling approach is based on the local charge balance and on the description of compound-specific and spatially variable diffusive/dispersive fluxes. The multicomponent ionic transport code...... is coupled with the geochemical code PHREEQC-3 by utilizing the IPhreeqc module, thus enabling to perform the geochemical calculations included in the PHREEQC's reaction package. The multicomponent reactive transport code is benchmarked with different 1-D and 2-D transport problems. Successively......, conservative and reactive transport examples are presented to demonstrate the capability of the proposed model to simulate transport of charged species in heterogeneous porous media with spatially variable physical and chemical properties. The results reveal that the Coulombic cross-coupling between dispersive...

  15. Colloids: a review of current knowledge with a view to application to phenomena of transportation within PWR; Colloides: point de vue sur les connaissances actuelles en vue d`une application aux phenomenes de transport dans les REP

    Energy Technology Data Exchange (ETDEWEB)

    Guinard, L.


    In an attempt to minimise dosimetry within the primary circuit of PWR units, research is being carried out into understanding the phenomena of transportation and deposition of corrosion products. It is therefore desirable to known the form of these corrosion products and the laws governing this form. It is generally considered that they are in soluble or particulate form. A third starts with a general presentation of colloids and goes on to define points which are useful, both on a theoretical and experimental level, in terms of application to phenomena of transportation within PWRs. (author). 69 refs., 30 figs., 6 tabs., 3 appends.

  16. The properties and transport phenomena in oxide films on iron, nickel, chromium and their alloys in aqueous environments

    Energy Technology Data Exchange (ETDEWEB)

    Laitinen, T.; Bojinov, M.; Betova, I.; Maekelae, K.; Saario, T. [VTT Manufacturing Technology, Espoo (Finland)


    . In addition, the films are to a large extent influenced by the kinetic factors determining their growth rate and steady state thickness. Thus a thermodynamic consideration of the film is not sufficient to model and predict its growth and dissolution. Instead, kinetic models based on in situ experimental data are required. The kinetic models presented in the literature for both ambient and high-temperature aqueous oxidation of metals lack a correlation between the structure of the oxide films and their electronic and ionic properties. Also, a quantitative treatment and thus the capability to predict material behaviour in varying conditions is lacking. A comprehensive understanding of the correlation between applied water chemistry, the behaviour of oxide films and optimum performance of the plant is thus also lacking. The situation calls for more experimental work combined with comprehensive modelling of the behaviour of both the compact and the porous part of the oxide film formed on a metal surface. This will make it possible to recognise the rate-limiting steps of the processes in the film, and thus to influence the rate of activity incorporation and different corrosion phenomena related to transport of species in the film. (author) 210 refs.

  17. Transport of Sr 2+ and SrEDTA 2- in partially-saturated and heterogeneous sediments (United States)

    Pace, M. N.; Mayes, M. A.; Jardine, P. M.; McKay, L. D.; Yin, X. L.; Mehlhorn, T. L.; Liu, Q.; Gürleyük, H.


    Strontium-90 has migrated deep into the unsaturated subsurface beneath leaking storage tanks in the Waste Management Areas (WMA) at the U.S. Department of Energy's (DOE) Hanford Reservation. Faster than expected transport of contaminants in the vadose zone is typically attributed to either physical hydrologic processes such as development of preferential flow pathways, or to geochemical processes such as the formation of stable, anionic complexes with organic chelates, e.g., ethylenediaminetetraacetic acid (EDTA). The goal of this paper is to determine whether hydrological processes in the Hanford sediments can influence the geochemistry of the system and hence control transport of Sr 2+ and SrEDTA 2-. The study used batch isotherms, saturated packed column experiments, and an unsaturated transport experiment in an undisturbed core. Isotherms and repacked column experiments suggested that the SrEDTA 2- complex was unstable in the presence of Hanford sediments, resulting in dissociation and transport of Sr 2+ as a divalent cation. A decrease in sorption with increasing solid:solution ratio for Sr 2+ and SrEDTA 2- suggested mineral dissolution resulted in competition for sorption sites and the formation of stable aqueous complexes. This was confirmed by detection of MgEDTA 2-, MnEDTA 2-, PbEDTA 2-, and unidentified Sr and Ca complexes. Displacement of Sr 2+ through a partially-saturated undisturbed core resulted in less retardation and more irreversible sorption than was observed in the saturated repacked columns, and model results suggested a significant reservoir (49%) of immobile water was present during transport through the heterogeneous layered sediments. The undisturbed core was subsequently disassembled along distinct bedding planes and subjected to sequential extractions. Strontium was unequally distributed between carbonates (49%), ion exchange sites (37%), and the oxide (14%) fraction. An inverse relationship between mass wetness and Sr suggested that

  18. Time-variant Lagrangian transport formulation reduces aggregation bias of water and solute mean travel time in heterogeneous catchments (United States)

    Danesh-Yazdi, Mohammad; Botter, Gianluca; Foufoula-Georgiou, Efi


    Lack of hydro-bio-chemical data at subcatchment scales necessitates adopting an aggregated system approach for estimating water and solute transport properties, such as residence and travel time distributions, at the catchment scale. In this work, we show that within-catchment spatial heterogeneity, as expressed in spatially variable discharge-storage relationships, can be appropriately encapsulated within a lumped time-varying stochastic Lagrangian formulation of transport. This time (variability) for space (heterogeneity) substitution yields mean travel times (MTTs) that are not significantly biased to the aggregation of spatial heterogeneity. Despite the significant variability of MTT at small spatial scales, there exists a characteristic scale above which the MTT is not impacted by the aggregation of spatial heterogeneity. Extensive simulations of randomly generated river networks reveal that the ratio between the characteristic scale and the mean incremental area is on average independent of river network topology and the spatial arrangement of incremental areas.

  19. Comparison between field measurements and numerical simulation of steady-state solute transport in a heterogeneous soil profile

    Directory of Open Access Journals (Sweden)

    J. Vanderborght


    Full Text Available Abstract: Field-scale solute dispersion is determined by water flow heterogeneity which results from spatial variability of soil hydraulic properties and soil moisture state. Measured variabilities of soil hydraulic properties are highly sensitive to the experimental method. Field-scale dispersion derived from leaching experiments in a macroporous loam soil was compared with field-scale dispersion obtained with numerical simulations in heterogeneous random fields. Four types of random fields of hydraulic properties having statistical properties derived from four different types of laboratory measurements were considered. Based on this comparison, the measurement method depicting heterogeneities of hydraulic properties most relevant to field-scale solute transport was identified. For unsaturated flow, the variability of the hydraulic conductivity characteristic measured on a small soil volume was the most relevant parameter. For saturated flow, simulated dispersion underestimated the measured dispersion and it was concluded that heterogeneity of macroscopic hydraulic properties could not represent solute flow heterogeneity under these flow conditions. Field-scale averaged solute concentrations depend both on the detection method and the averaging procedure. Flux-averaged concentrations (relevant to practical applications differ from volume-averaged or resident concentrations (easy to measure, especially when water flow is more heterogeneous. Simulated flux and resident concentrations were subsequently used to test two simple one-dimensional transport models in predicting flux concentrations when they are calibrated on resident concentrations. In the first procedure, solute transport in a heterogeneous soil is represented by a 1-D convection dispersion process. The second procedure was based on the relation between flux and resident concentrations for a stochastic convective process. Better predictions of flux concentrations were obtained using

  20. LUGH an experimental facility for preferential flow-colloidal transport in heterogeneous unsaturated soil (United States)

    Angulo-Jaramillo, R.; Bien, L.; Hehn, V.; Winiarski, T.


    Colloidal particles transport through vadose zone can contribute to fast transport of contaminants into groundwater. The objective is to study the preferential flow and transport of colloids in heterogeneous unsaturated soil subjected to high organic matter entry. A physically based model is developed based on a large laboratory lysimeter than usual laboratory column experiments. LUGH-Lysimeter for Unsaturated Groundwater Hydrodynamics- is used to embed a soil monolith (1.6 m3) made of different cross-bedded lithological types with contrasting hydraulic properties. The filling material is a carbonated graded sand and gravel from the fluvioglacial vadose zone of the east of Lyon (France). Materials are 3D arranged on contrasting textured lithofacies analogous to the sedimentary lithology of a fluvioglacial cross-bedded deposit. Tracer (Br 1E-2M) and colloid solutions were injected in a pulse mode using a rainfall simulator. Colloid solution is Chlamydomonas reinhardtii at 3.2E+6 units/mL concentration. These unicellular algae can be considered as spherical particles from 6 to 10 μm in diam. Their resistance and doubling time of cell growth are greater than the transfer time in the lysimeter. Algae moving into the porous medium do not immediately reproduce, and then the population size remains constant. During this period, called the lag phase (1 to 2 days), the cells are metabolically active and increase only in cell size. Tensiometers, TDR and electric resistivity enable measurements of the parameters related to flow, solute and colloid transfer. Eluted solutions are sampled by 15 separated fraction collectors, leading to independent breakthrough curves. Eluted colloid concentration is measured by spectrofluorometry. The model approach combines Richards equation, coupled to a convective-dispersive equation with a source/sink term for particle transport and mobilization. Macroscopic particle attachment/detachment from pores is assumed to follow first-order kinetics

  1. Prediction of solute transport in a heterogeneous aquifer utilizing hydraulic conductivity and specific storage tomograms (United States)

    Jiménez, S.; Brauchler, R.; Hu, R.; Hu, L.; Schmidt, S.; Ptak, T.; Bayer, P.


    A sequential procedure of hydraulic tomographical inversion is applied to characterize at high resolution the spatial heterogeneity of hydraulic conductivity and specific storage at the field test site Stegemühle, Germany. The shallow aquifer at this site is examined by five short-term multilevel pumping tests with 30 pumping-observation pairs between two wells. Utilizing travel time diagnostics of the recorded pressure response curves, fast eikonal-based inversion is shown to deliver insight into the sedimentary structures. Thus, the structural information from the generated travel time tomogram is exploited to constrain full calibration of the pressure response curves. Based on lateral extrapolation from the measured inter-well profile, a three-dimensional reconstruction of the aquifer is obtained. It is demonstrated that calibration of spatially variable specific storage in addition to hydraulic conductivity can improve the fitting of the model while the structural features are only slightly changed. At the field site, two tracer tests with uranine and sodium-naphthionate were also performed and their concentrations were monitored for 2 months. The measured tracer breakthrough curves are employed for independent validation of the hydraulic tomographical reconstruction. It is demonstrated that major features of the observed solute transport can be reproduced, and structures relevant for macrodispersive tracer spreading could be resolved. However, for the mildly heterogeneous aquifer, the tracer breakthrough curves can also be approximated by a simplified homogeneous model with higher dispersivity. Therefore, improved validation results that capture specific characteristics of the breakthrough curves would require additional hydraulic measurements.

  2. Heterogeneity of passenger exposure to air pollutants in public transport microenvironments (United States)

    Yang, Fenhuan; Kaul, Daya; Wong, Ka Chun; Westerdahl, Dane; Sun, Li; Ho, Kin-fai; Tian, Linwei; Brimblecombe, Peter; Ning, Zhi


    Epidemiologic studies have linked human exposure to pollutants with adverse health effects. Passenger exposure in public transport systems contributes an important fraction of daily burden of air pollutants. While there is extensive literature reporting the concentrations of pollutants in public transport systems in different cities, there are few studies systematically addressing the heterogeneity of passenger exposure in different transit microenvironments, in cabins of different transit vehicles and in areas with different characteristics. The present study investigated PM2.5 (particulate matter with aerodynamic diameters smaller than 2.5 μm), black carbon (BC), ultrafine particles (UFP) and carbon monoxide (CO) pollutant concentrations in various public road transport systems in highly urbanized city of Hong Kong. Using a trolley case housing numerous portable air monitors, we conducted a total of 119 trips during the campaign. Transit microenvironments, classified as 1). busy and secondary roadside bus stops; 2). open and enclosed termini; 3). above- and under-ground Motor Rail Transport (MTR) platforms, were investigated and compared to identify the factors that may affect passenger exposures. The pollutants inside bus and MTR cabins were also investigated together with a comparison of time integrated exposure between the transit modes. Busy roadside and enclosed termini demonstrated the highest average particle concentrations while the lowest was found on the MTR platforms. Traffic-related pollutants BC, UFP and CO showed larger variations than PM2.5 across different microenvironments and areas confirming their heterogeneity in urban environments. In-cabin pollutant concentrations showed distinct patterns with BC and UFP high in diesel bus cabins and CO high in LPG bus cabins, suggesting possible self-pollution issues and/or penetration of on-road pollutants inside cabins during bus transit. The total passenger exposure along selected routes, showed bus

  3. Towards Understanding the Solvent-Dynamic Control of the Transport and Heterogeneous Electron-Transfer Processes in Ionic Liquids. (United States)

    Bhat, Mohsin Ahmad; Ingole, Pravin P; Randriamahazaka, Hyacinthe


    The impact of temperature-induced changes in solvent dynamics on the diffusion coefficient and standard rate constant k(0) for heterogeneous electron transfer (ET) of ethylferrocene (EFc) in 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6 ]) is investigated. The results are analysed to understand the impact of solvent-dynamic control, solute-solvent interactions and solvent friction on the transport of redox probes and k(0) . Concentration dependence of the diffusion coefficient of EFc in [BMIM][PF6 ] is observed. This is attributed to the solute-induced enhancement of the structural organisation of the ionic liquid (IL), which is supported by the concentration-dependent UV/Vis absorption and photoluminescence responses of EFc/[BMIM][PF6 ] solutions. Similar values of the activation energies for mass transport and ET and a linear relationship between the diffusion coefficient and the heterogeneous ET rate is observed. The ratio between the diffusion coefficient and the heterogeneous rate constant allows a characteristic length Ld , which is temperature-independent, to be introduced. The presented results clearly establish that mass transport and heterogeneous ET of redox probes are strongly correlated in ILs. It is proposed that the apparent kinetics of heterogeneous ET reactions in ILs can be explained in terms of their impact on thermal equilibration, energy dissipation and thermal excitation of redox-active probes. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Thermodynamically Constrained Averaging Theory Approach for Modeling Flow and Transport Phenomena in Porous Medium Systems: 8. Interface and Common Curve Dynamics. (United States)

    Gray, William G; Miller, Cass T


    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.

  5. Characterization of the role of heterogeneous advection and diffusion on transport in weathered and fractured granite (United States)

    Guihéneuf, N.; Boisson, A.; Bour, O.; Le Borgne, T.; Marechal, J.; Nigon, B.; Wajiddudin, M.; Ahmed, S.


    The prediction of transport in weathered and fractured rocks is critical as it represents the primary control of contaminant transfer from the subsurface in many parts of the world. This is the case in Southern India, where the subsurface is composed mainly of weathered and fractured granite and where the overexploitation of the groundwater resource since the 70's has led to high water table depletion and strong groundwater quality deterioration. One key issue for modelling transport in such systems is to quantify the respective role of advective heterogeneities and matrix diffusion, which can both lead to strongly non Fickian transport properties. We investigate this question by analysing tracer test experiments performed under different flow configurations at a fractured granite experimental site located in Andhra Pradesh (India). We performed both convergent and push-pull tracer tests within the same fracture and at different scales. Three convergent tracer tests were performed with a solution of fluorescein for different pumping rate and for different distances between injection and pumping boreholes: 6, 30 and 41 meters. To evaluate diffusive process, we performed two long-duration push-pull tests (push time of 3 hours) with a solution of two conservative tracers of different diffusion coefficient (fluorescein and sodium chloride). We performed also six others push-pull tests with only fluorescein but for a variable push times of 14 min and 55 min with or without resting time of about 60 min. The late-time behaviour on the breakthrough curves (BTCs) obtained for all convergent tracer tests showed a power-law slope of -2. Two of them showed an inflexion in the BTCs suggesting the existence of two independent flow paths and thus a highly channelized flow. The long-duration push-pull tests showed similar late-time behaviour with a power-law slope of -2.2 for both tracers. The six others push-pull tests showed a variation of power-law exponent from -3 to -2

  6. Coupling 3D Monte Carlo light transport in optically heterogeneous tissues to photoacoustic signal generation

    Directory of Open Access Journals (Sweden)

    Steven L. Jacques


    Full Text Available The generation of photoacoustic signals for imaging objects embedded within tissues is dependent on how well light can penetrate to and deposit energy within an optically absorbing object, such as a blood vessel. This report couples a 3D Monte Carlo simulation of light transport to stress wave generation to predict the acoustic signals received by a detector at the tissue surface. The Monte Carlo simulation allows modeling of optically heterogeneous tissues, and a simple MATLAB™ acoustic algorithm predicts signals reaching a surface detector. An example simulation considers a skin with a pigmented epidermis, a dermis with a background blood perfusion, and a 500-μm-dia. blood vessel centered at a 1-mm depth in the skin. The simulation yields acoustic signals received by a surface detector, which are generated by a pulsed 532-nm laser exposure before and after inserting the blood vessel. A MATLAB™ version of the acoustic algorithm and a link to the 3D Monte Carlo website are provided.

  7. Heterogeneous nucleation promotes carrier transport in solution-processed organic field-effect transistors

    KAUST Repository

    Li, Ruipeng


    A new way to investigate and control the growth of solution-cast thin films is presented. The combination of in situ quartz crystal microbalance measurements with dissipation capabilities (QCM-D) and in situ grazing-incidence wide-angle X-ray scattering (GIWAXS) in an environmental chamber provides unique quantitative insights into the time-evolution of the concentration of the solution, the onset of nucleation, and the mode of growth of the organic semiconductor under varied drying conditions. It is demonstrated that careful control over the kinetics of solution drying enhances carrier transport significantly by promoting phase transformation predominantly via heterogeneous nucleation and sustained surface growth of a highly lamellar structure at the solid-liquid interface at the expense of homogeneous nucleation. A new way to investigate and control the growth of drop-cast thin films is presented. The solution-processing of small-molecule thin films of TIPS-pentacene is investigated using time-resolved techniques to reveal the mechanisms of nucleation and growth leading to solid film formation. By tuning the drying speed of the solution, the balance between surface and bulk growth modes is altered, thereby controlling the lamellar formation and tuning the carrier mobility in organic field-effect transistors Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Effects of lung ventilation-perfusion and muscle metabolism-perfusion heterogeneities on maximal O2 transport and utilization. (United States)

    Cano, I; Roca, J; Wagner, P D


    We expanded a prior model of whole-body O2 transport and utilization based on diffusive O2 exchange in the lungs and tissues to additionally allow for both lung ventilation-perfusion and tissue metabolism-perfusion heterogeneities, in order to estimate V̇O2 and mitochondrial PO2 (PmO2) during maximal exercise. Simulations were performed using data from (a) healthy fit subjects exercising at sea level and at altitudes up to the equivalent of Mount Everest and (b) patients with mild and severe chronic obstructive pulmonary disease (COPD) exercising at sea level. Heterogeneity in skeletal muscle may affect maximal O2 availability more than heterogeneity in lung, especially if mitochondrial metabolic capacity (V̇ MAX ) is only slightly higher than the potential to deliver O2 , but when V̇ MAX is substantially higher than O2 delivery, the effect of muscle heterogeneity is comparable to that of lung heterogeneity. Skeletal muscle heterogeneity may result in a wide range of potential mitochondrial PO 2 values, a range that becomes narrower as V̇ MAX increases; in regions with a low ratio of metabolic capacity to blood flow, PmO2 can exceed that of mixed muscle venous blood. The combined effects of lung and peripheral heterogeneities on the resistance to O2 flow in health decreases with altitude. Previous models of O2 transport and utilization in health considered diffusive exchange of O2 in lung and muscle, but, reasonably, neglected functional heterogeneities in these tissues. However, in disease, disregarding such heterogeneities would not be justified. Here, pulmonary ventilation-perfusion and skeletal muscle metabolism-perfusion mismatching were added to a prior model of only diffusive exchange. Previously ignored O2 exchange in non-exercising tissues was also included. We simulated maximal exercise in (a) healthy subjects at sea level and altitude, and (b) COPD patients at sea level, to assess the separate and combined effects of pulmonary and peripheral

  9. A numerical study of nonlinear diffusion phenomena in heterogeneous media: energy transfer at diverse blow-up modes and self-organisation processes (United States)

    Skiba, Yuri N.; Filatov, Denis M.


    A detailed analysis of a new method for numerical simulation of nonlinear diffusion phenomena is carried out. The method is based on operator splitting performed in time and space, and yields highly accurate solutions in complex 2D and 3D computational domains. After providing a circumstantial mathematical description of the developed method, we test it in several numerical experiments aimed, firstly, to model energy transfer at diverse modes of evolution of the dynamical system, and, secondly, to simulate self-organisation processes typical for real-world applications. A discussion of the outcomes of the numerical experiments is given. This is a follow-up paper of our recent original results presented at the 19th European conference on mathematics for industry.

  10. The use of laboratory experiments for the study of conservative solute transport in heterogeneous porous media (United States)

    Silliman, S. E.; Zheng, L.; Conwell, P.

    Laboratory experiments on heterogeneous porous media (otherwise known as intermediate scale experiments, or ISEs) have been increasingly relied upon by hydrogeologists for the study of saturated and unsaturated groundwater systems. Among the many ongoing applications of ISEs is the study of fluid flow and the transport of conservative solutes in correlated permeability fields. Recent advances in ISE design have provided the capability of creating correlated permeability fields in the laboratory. This capability is important in the application of ISEs for the assessment of recent stochastic theories. In addition, pressure-transducer technology and visualization methods have provided the potential for ISEs to be used in characterizing the spatial distributions of both hydraulic head and local water velocity within correlated permeability fields. Finally, various methods are available for characterizing temporal variations in the spatial distribution (and, thereby, the spatial moments) of solute concentrations within ISEs. It is concluded, therefore, that recent developments in experimental techniques have provided an opportunity to use ISEs as important tools in the continuing study of fluid flow and the transport of conservative solutes in heterogeneous, saturated porous media. Résumé Les hydrogéologues se sont progressivement appuyés sur des expériences de laboratoire sur des milieux poreux hétérogènes (connus aussi par l'expression "Expériences àéchelle intermédiaire", ISE) pour étudier les zones saturées et non saturées des aquifères. Parmi les nombreuses applications en cours des ISE, il faut noter l'étude de l'écoulement de fluide et le transport de solutés conservatifs dans des champs aux perméabilités corrélées. Les récents progrès du protocole des ISE ont donné la possibilité de créer des champs de perméabilités corrélées au laboratoire. Cette possibilité est importante dans l'application des ISE pour l'évaluation des th

  11. Response Analysis of Multiple Tracers for Assessment of Fate and Transport Heterogeneities in a Karstified Limestone Model (United States)

    Toro, J.; Padilla, I. Y.


    Karst terrains have high capacity to transport and store large amounts of water. These features makekarst vulnerable to potential contamination of hazardous chemical substances. The interest to delineateand predict flow and transport processes in karst groundwater systems has increased due to thetremendous challenge on detecting and removing contaminants in these systems. Characterization andquantification of flow and transport processes at field-scale is limited by low resolution ofspatiotemporal data. Studies at the laboratory scale can provide fundamental knowledge oncharacterization and quantification tools that can be applied at the field scale to enhance resolution.This work developed an intermediate karstified lab-scale physical model (IKLPM) to study fate andtransport (F&T) processes and assess viable tools to characterize heterogeneities in karst systems. Two-dimensional temporal concentration distributions (TCDs) obtained from calcium chloride, uranine, andrhodamine wt tracer experiments in the IKLPM were analyzed using method of moments and CXTFIT tocharacterize and quantify fate and transport parameters in the system at various flow rates. TCDsshowed variability associated with differences in the dominant physicochemical processes affecting theF&T of the tracers. The estimated F&T parameters for the tracers revealed high spatial variability relatedto preferential flow heterogeneities and scale dependence. Future work will integrate the experimentalresults to develop technologies for enhanced spatial characterization of transport regions in karstgroundwater systems. The development of these technologies will improve our ability to predict fateand transport of contaminants in these systems and reduce impacts to the environment and humanhealth.

  12. Discontinuous finite element and characteristics methods for neutrons transport equation solution in heterogeneous grids; Resolution de l'equation du transport des neutrons par les methodes des elements finis discontinus et des caracteristiques structurees appliquees a des maillages heterogenes

    Energy Technology Data Exchange (ETDEWEB)

    Masiello, E


    The principal goal of this manuscript is devoted to the investigation of a new type of heterogeneous mesh adapted to the shape of the fuel pins (fuel-clad-moderator). The new heterogeneous mesh guarantees the spatial modelling of the pin-cell with a minimum of regions. Two methods are investigated for the spatial discretization of the transport equation: the discontinuous finite element method and the method of characteristics for structured cells. These methods together with the new representation of the pin-cell result in an appreciable reduction of calculation points. They allow an exact modelling of the fuel pin-cell without spatial homogenization. A new synthetic acceleration technique based on an angular multigrid is also presented for the speed up of the inner iterations. These methods are good candidates for transport calculations for a nuclear reactor core. A second objective of this work is the application of method of characteristics for non-structured geometries to the study of double heterogeneity problem. The letters is characterized by fuel material with a stochastic dispersion of heterogeneous grains, and until now was solved with a model based on collision probabilities. We propose a new statistical model based on renewal-Markovian theory, which makes possible to take into account the stochastic nature of the problem and to avoid the approximations of the collision probability model. The numerical solution of this model is guaranteed by the method of characteristics. (author)

  13. Modeling of the Ionic Multi-Species Transport Phenomena in Electrokinetic Processes and Comparison with Experimental Results

    DEFF Research Database (Denmark)

    Paz-Garcia, Juan Manuel; Johannesson, Björn; Ottosen, Lisbeth M.


    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....

  14. Theoretical analysis of non-Gaussian heterogeneity effects on subsurface flow and transport (United States)

    Riva, Monica; Guadagnini, Alberto; Neuman, Shlomo P.


    Much of the stochastic groundwater literature is devoted to the analysis of flow and transport in Gaussian or multi-Gaussian log hydraulic conductivity (or transmissivity) fields, Y(x)=ln\\func K(x) (x being a position vector), characterized by one or (less frequently) a multiplicity of spatial correlation scales. Yet Y and many other variables and their (spatial or temporal) increments, ΔY, are known to be generally non-Gaussian. One common manifestation of non-Gaussianity is that whereas frequency distributions of Y often exhibit mild peaks and light tails, those of increments ΔY are generally symmetric with peaks that grow sharper, and tails that become heavier, as separation scale or lag between pairs of Y values decreases. A statistical model that captures these disparate, scale-dependent distributions of Y and ΔY in a unified and consistent manner has been recently proposed by us. This new "generalized sub-Gaussian (GSG)" model has the form Y(x)=U(x)G(x) where G(x) is (generally, but not necessarily) a multiscale Gaussian random field and U(x) is a nonnegative subordinator independent of G. The purpose of this paper is to explore analytically, in an elementary manner, lead-order effects that non-Gaussian heterogeneity described by the GSG model have on the stochastic description of flow and transport. Recognizing that perturbation expansion of hydraulic conductivity K=eY diverges when Y is sub-Gaussian, we render the expansion convergent by truncating Y's domain of definition. We then demonstrate theoretically and illustrate by way of numerical examples that, as the domain of truncation expands, (a) the variance of truncated Y (denoted by Yt) approaches that of Y and (b) the pdf (and thereby moments) of Yt increments approach those of Y increments and, as a consequence, the variogram of Yt approaches that of Y. This in turn guarantees that perturbing Kt=etY to second order in σYt (the standard deviation of Yt) yields results which approach those we obtain

  15. Impacts of Physical and Chemical Heterogeneity on Cocontaminant Transport in a Sandy Porous Medium (United States)

    Tompson, Andrew F. B.; Schafer, Annette L.; Smith, Robert W.


    A simplified numerical study of the transport of a uranyl-citric acid mixture through a nonuniform and reactive sandy porous medium is presented. The study seeks to identify the more important impacts of medium heterogeneity, as embodied in spatially variable physical and chemical properties, on the migration and dilution rates of a model cocontaminant mixture, as well as on the overall partitioning among the aqueous and solid species formed from complexation and sorption reactions. Solid phase reactions are considered to occur on hydrous-ferric oxide (goethite) coatings on the sand and are controlled by the abundance of the oxide as a function of the specific sand surface area and larger-scale patterns of oxide deposition. The simulations involve calculation of fluid flow and chemical migration within highly resolved, two- and three-dimensional regions with synthetic material properties that approximate observed conditions in a sandy coastal aquifer. Model simulations in this system indicate that (1) the impact of correlation between reactive surface area and hydraulic conductivity, although evident, seems much less significant than the overall abundance and distribution of the reactive area, such as the kind of banded goethite patterns observed in a coastal sand body; (2) strong multicomponent interactions clearly reinforce the need to treat the mixture as a coupled system, as opposed to a series of independently reactive compounds; (3) simplifications can be made in extremely dilute problems that allow retardation effects to become concentration independent; and (4) for nonlinear reaction problems, three-dimensional models will be more appropriate than two-dimensional models to the extent that dispersion in the added dimension accelerates chemical dilution rates.

  16. Direct numerical simulation of reactive flow and modeling of pore-scale transport phenomena in porous media (United States)

    Nomeli, Mohammad; Riaz, Amir


    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.

  17. Study of transport phenomena in laser-driven, non- equilibrium plasmas in the presence of external magnetic fields (United States)

    Kemp, G. Elijah; Mariscal, D. A.; Williams, G. J.; Blue, B. E.; Colvin, J. D.; Fears, T. M.; Kerr, S. M.; May, M. J.; Moody, J. D.; Strozzi, D. J.; Lefevre, H. J.; Klein, S. R.; Kuranz, C. C.; Manuel, M. J.-E.; Gautier, D. C.; Montgomery, D. S.


    We present experimental and simulation results from a study of thermal transport inhibition in laser-driven, mid-Z, non-equilibrium plasmas in the presence external magnetic fields. The experiments were performed at the Jupiter Laser Facility at LLNL, where x-ray spectroscopy, proton radiography, and Brillouin backscatter data were simultaneously acquired from sub-critical-density, Ti-doped silica aerogel foams driven by a 2 ω laser at 5 ×1014 W /cm2 . External B-field strengths up to 20 T (aligned antiparallel to the laser propagation axis) were provided by a capacitor-bank-driven Helmholtz coil. Pre-shot simulations with Hydra, a radiation-magnetohydrodyanmics code, showed increasing electron plasma temperature with increasing B-field strength - the result of thermal transport inhibition perpendicular to the B-field. The influence of this thermal transport inhibition on the experimental observables as a function of external field strength and target density will be shown and compared with simulations. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344 and funded by LDRD project 17-ERD-027.

  18. Insights into interstitial flow, shear stress, and mass transport effects on ECM heterogeneity in bioreactor-cultivated engineered cartilage hydrogels. (United States)

    Chen, Tony; Buckley, Mark; Cohen, Itai; Bonassar, Lawrence; Awad, Hani A


    Interstitial flow in articular cartilage is secondary to compressive and shear deformations during joint motion and has been linked with the well-characterized heterogeneity in structure and composition of its extracellular matrix. In this study, we investigated the effects of introducing gradients of interstitial flow on the evolution of compositional heterogeneity in engineered cartilage. Using a parallel-plate bioreactor, we observed that Poiseuille flow stimulation of chondrocyte-seeded agarose hydrogels led to an increase in glycosaminoglycan and type II collagen deposition in the surface region of the hydrogel exposed to flow. Experimental measurements of the interstitial flow fields based on the fluorescence recovery after photobleaching technique suggested that the observed heterogeneity in composition is associated with gradients in interstitial flow in a boundary layer at the hydrogel surface. Interestingly, the interstitial flow velocity profiles were nonlinearly influenced by flow rate, which upon closer examination led us to the original observation that the apparent hydrogel permeability decreased exponentially with increased interfacial shear stress. We also observed that interstitial flow enhances convective mass transport irrespective of molecular size within the boundary layer near the hydrogel surface and that the convective contribution to transport diminishes with depth in association with interstitial flow gradients. The implications of the nonlinearly inverse relationship between the interfacial shear stress and the interstitial flux and permeability and its consequences for convective transport are important for tissue engineering, since porous scaffolds comprise networks of Poiseuille channels (pores) through which interstitial flow must navigate under mechanical stimulation or direct perfusion.

  19. Helium Bubbles Cavitation Phenomena in Pb-15.7Li and Potential Impact on Tritium Transport Behaviour in HCLL Breeding Channels

    Energy Technology Data Exchange (ETDEWEB)

    Sedano, L. A.


    COMPU task is devoted to develop a Process Flow Diagram (PFD) modelling tool for DEMO tritium cycle for HCLL and HCPB blanket lines for DEMO. At the actual stage of definition of HCLL blanket design line this global objective requires to progress specifically on the physical reliability of tritium transport assessments at blanket design level. A rough reliability assessment with the identify cation of physical phenomena determining permeation rates into the coolant was tentatively advanced in COMPU Task Deliverable 1. In HCLL design, the tritium diffusion in the alloy under the flow conditions and radiation effects in Pb15.7Li can be theoretically justifies ed as the rate limiting processes for tritium transfer into the coolant. This Deliverable 2 focuses on the analysis of a specific radiation effect: the potential role of helium bubbles in Pb15.7Li, the discussion of its implications on tritium assessment for HCLL design and consequently the analysis of its quantitative impact (as cycle input) on HCLL PFD tritium cycle design. Thus, the contents of this report investigate: (1) the rationality of the consideration on HCLL design of helium bubble cavitation phenomena in irradiated Pb15.7Li channels on the base of fundamental analysis (He solution states in Pb15.7Li) from empirical clues provided by Pb15.7Li irradiation tests, (2) a preliminary rough He-bubble cavitation design assessment and bases for a more precise FEM calculation for helium bubble cavitation phenomena in HCLL blanket channels, (3) the analysis of direct experimental data and numerical developments needed for a precise cavitation assessment and (4) a proposal of the lay-out and general specifications of an integral proof-of-principle Cavitation Experiment (Cevitex) of Helium in Pb15.7Li. (Author) 40 refs.

  20. Finite element computation of multi-physical micropolar transport phenomena from an inclined moving plate in porous media (United States)

    Shamshuddin, MD.; Anwar Bég, O.; Sunder Ram, M.; Kadir, A.


    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.

  1. Finite element computation of multi-physical micropolar transport phenomena from an inclined moving plate in porous media (United States)

    Shamshuddin, MD.; Anwar Bég, O.; Sunder Ram, M.; Kadir, A.


    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.

  2. Studies of Band Structure and Free Carrier Scattering in Transparent Conducting Oxides Based on Combined Measurements of Electron Transport Phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Kaydanov, V. I.; Coutts, T. J.; Young, D. L.


    Experimental methods are discussed for studying band structure, effective mass, and other electronic properties relevant to mobility, including scattering mechanisms, relaxation time, and the influence of grain boundaries (GBs) in polycrystalline transparent conducting oxide (TCO) films. Impedance spectroscopy permits evaluation of the GB potential barrier height and density-of-states. These studies enable an estimate of the limiting mobility achievable for practical transparent conducting oxides to be made. The equipment for measurement of the four transport coefficients is discussed, and examples of its application to films of ZnO, SnO2, and Cd2SnO4 are given.

  3. Molecular dynamics study on mechanism of preformed particle gel transporting through nanopores: Surface chemistry and heterogeneity (United States)

    Cui, Peng; Zhang, Heng; Ma, Ying; Hao, Qingquan; Liu, Gang; Sun, Jichao; Yuan, Shiling


    The translocation behavior of preformed particle gel (PPG) in porous media is crucial for its application in enhanced oil recovery. By means of non-equilibrium molecular dynamics simulation, the translocation mechanism of PPG confined in different silica nanopores were investigated. The influence of surface chemistry and chemical heterogeneity of silica nanopore on the translocation process was revealed. As the degree of surface hydroxylation increases and the heterogeneity decreases, the pulling force needed to drive PPG decreases. We infer that the nanopore's surface (i.e. surface chemistry and heterogeneity) affects the translocation of PPG indirectly by forming different hydration layers.

  4. Transport phenomena and conductivity mechanism in Sm doped Bi4V2−xSmxO11 ceramics

    Directory of Open Access Journals (Sweden)

    Sasmitarani Bag


    Full Text Available The polycrystalline samples of Sm doped Bi4V2−xSmxO11 with x = 0.05, 0.10, 0.15 and 0.20 ceramics were prepared by using solid-state reaction technique. The structural characterization of the prepared samples were confirmed by X-ray powder diffraction (XRD and showed an orthorhombic and monoclinic phase. The nature of Nyquist plot confirms the presence of both grain and grain boundary effects for all Sm doped compounds. The grain resistance decreases with rise in temperature for all the samples and exhibits a typical negative temperature co-efficient of resistance (NTCR behavior. The ac conductivity spectrum obeys Jonscher's universal power law. The modulus analysis suggests a possible hopping mechanism for electrical transport processes of the materials. The nature of variation of dc conductivity suggests the Arrhenius type of electrical conductivity for all the samples.

  5. High-order Two-Fluid Plasma Solver for Direct Numerical Simulations of Magnetic Flows with Realistic Transport Phenomena (United States)

    Li, Zhaorui; Livescu, Daniel


    The two-fluid plasma equations with full transport terms, including temperature and magnetic field dependent ion and electron viscous stresses and heat fluxes, frictional drag force, and ohmic heating term have been solved by using the sixth-order non-dissipative compact scheme for plasma flows in several different regimes. In order to be able to fully resolve all the dynamically relevant time and length scales while maintaining computational feasibility, the assumptions of infinite speed of light and negligible electron inertia have been made. The accuracy and robustness of this two-fluid plasma solver in handling plasma flows have been tested against a series of canonical problems, such as Alfven-Whistler dispersion relation, electromagnetic plasma shock, magnetic reconnection, etc. For all test cases, grid convergence tests have been conducted to achieve fully resolved results. The roles of heat flux, viscosity, resistivity, Hall and Biermann battery effects, are investigated for the canonical flows studied.

  6. Imaging geochemical heterogeneities using inverse reactive transport modeling: An example relevant for characterizing arsenic mobilization and distribution

    DEFF Research Database (Denmark)

    Fakhreddine, Sarah; Lee, Jonghyun; Kitanidis, Peter K.


    The spatial distribution of reactive minerals in the subsurface is often a primary factor controlling the fate and transport of contaminants in groundwater systems. However, direct measurement and estimation of heterogeneously distributed minerals are often costly and difficult to obtain. While......-bearing reactive minerals as aquifer contaminants. We use synthetic applications to demonstrate the ability of inverse modeling techniques combined with mechanistic reactive transport models to image reactive mineral lenses in the subsurface and quantify estimation error using indirect, commonly measured......, synthetic dissolved oxygen data and forward reactive transport simulations are used to image the spatial distribution of As-bearing pyrite using the Principal Component Geostatistical Approach (PCGA) for inverse modeling. (C) 2015 Elsevier Ltd. All rights reserved....

  7. Kinetic Modeling of ABCG2 Transporter Heterogeneity: A Quantitative, Single-Cell Analysis of the Side Population Assay. (United States)

    Prasanphanich, Adam F; White, Douglas E; Gran, Margaret A; Kemp, Melissa L


    The side population (SP) assay, a technique used in cancer and stem cell research, assesses the activity of ABC transporters on Hoechst staining in the presence and absence of transporter inhibition, identifying SP and non-SP cell (NSP) subpopulations by differential staining intensity. The interpretation of the assay is complicated because the transporter-mediated mechanisms fail to account for cell-to-cell variability within a population or adequately control the direct role of transporter activity on staining intensity. We hypothesized that differences in dye kinetics at the single-cell level, such as ABCG2 transporter-mediated efflux and DNA binding, are responsible for the differential cell staining that demarcates SP/NSP identity. We report changes in A549 phenotype during time in culture and with TGFβ treatment that correlate with SP size. Clonal expansion of individually sorted cells re-established both SP and NSPs, indicating that SP membership is dynamic. To assess the validity of a purely kinetics-based interpretation of SP/NSP identity, we developed a computational approach that simulated cell staining within a heterogeneous cell population; this exercise allowed for the direct inference of the role of transporter activity and inhibition on cell staining. Our simulated SP assay yielded appropriate SP responses for kinetic scenarios in which high transporter activity existed in a portion of the cells and little differential staining occurred in the majority of the population. With our approach for single-cell analysis, we observed SP and NSP cells at both ends of a transporter activity continuum, demonstrating that features of transporter activity as well as DNA content are determinants of SP/NSP identity.

  8. Heterogeneity of Rapid Sand Filters and Its Effect on Contaminant Transport and Nitrification Performance

    DEFF Research Database (Denmark)

    Lopato, Laure Rose; Galaj, Zofia; Delpont, Sébastien


    flow. A first-order nitrification reaction with spatially variable pore-water velocity could be interpreted as a zero-order reaction with a constant pore-water velocity. A model demonstrated that filter heterogeneity could result in higher filter outlet ammonium concentrations.......Laboratory and full-scale experiments were conducted to investigate the development and effect of heterogeneity caused by filter media nonuniformity, biofilm, particles, precipitates, and gas bubbles in rapid sand filters used for drinking-water treatment. Salt tracer experiments were conducted...... dispersivity of more than 33% in the 116 h after the start of filtration with a constant pore-water velocity and a zero-order nitrification rate of 9 mgN=L=h. The full-scale experiments showed that the rapid sand filter was heterogeneous with pore-water velocities ranging from 2.2 to 3:3 m=h for the same inlet...

  9. Multiscale Adapted Time-Splitting Technique for Nonisothermal Two-Phase Flow and Nanoparticles Transport in Heterogenous Porous Media

    KAUST Repository

    El-Amin, Mohamed F.


    This paper is devoted to study the problem of nonisothermal two-phase flow with nanoparticles transport in heterogenous porous media, numerically. For this purpose, we introduce a multiscale adapted time-splitting technique to simulate the problem under consideration. The mathematical model consists of equations of pressure, saturation, heat, nanoparticles concentration in the water–phase, deposited nanoparticles concentration on the pore–walls, and entrapped nanoparticles concentration in the pore–throats. We propose a multiscale time splitting IMplicit Pressure Explicit Saturation–IMplicit Temperature Concentration (IMPES-IMTC) scheme to solve the system of governing equations. The time step-size adaptation is achieved by satisfying the stability Courant–Friedrichs–Lewy (CFL<1) condition. Moreover, numerical test of a highly heterogeneous porous medium is provided and the water saturation, the temperature, the nanoparticles concentration, the deposited nanoparticles concentration, and the permeability are presented in graphs.

  10. Coupled transport phenomena in a clay from a Callovo-Oxfordian formation; Phenomenes de transport couples dans les argiles du Callovo-Oxfordien

    Energy Technology Data Exchange (ETDEWEB)

    Paszkuta, M


    Low permeability materials containing clay play an important role in practical life and natural environment. Indeed, the ability of clay soils to act as semi permeable membranes, that inhibit the passage of electrolytes, is of great interest. The major objective of this thesis is to evaluate the transport properties of natural clays and in particular coupled transports when a pressure gradient, an electrical field, a concentration gradient and a temperature gradient interact. The material is a compact argillite extracted in East France from a Callovo-Oxfordian formation which was supplied to us by ANDRA. NaCl was used as the main solute. Two series of experiments were performed to measure permeability, diffusion, conductivity, the electro-osmotic coefficient and the Soret coefficient. (author)

  11. Kinetically influenced terms for solute transport affected by heterogeneous and homogeneous classical reactions (United States)

    Bahr, J.M.


    This paper extends a four-step derivation procedure, previously presented for cases of transport affected by surface reactions, to transport problems involving homogeneous reactions. Derivations for these classes of reactions are used to illustrate the manner in which mathematical differences between reaction classes are reflected in the mathematical derivation procedures required to identify kinetically influenced terms. Simulation results for a case of transport affected by a single solution phase complexation reaction and for a case of transport affected by a precipitation-dissolution reaction are used to demonstrate the nature of departures from equilibrium-controlled transport as well as the use of kinetically influenced terms in determining criteria for the applicability of the local equilibrium assumption. A final derivation for a multireaction problem demonstrates the application of the generalized procedure to a case of transport affected by reactions of several classes. -from Author

  12. Selective transport between heterogeneous hyphal compartments via the plasma membrane lining septal walls of Aspergillus niger

    NARCIS (Netherlands)

    Bleichrodt, Robert-Jan; Vinck, Arman; Read, Nick D; Wösten, Han A B

    Hyphae of ascomycetes are compartmentalized by septa. The central pore in these septa allows for cytoplasmic streaming. However, many of these pores are closed by Woronin bodies in Aspergillus, which prevents cytoplasmic mixing and thus maintains hyphal heterogeneity. Here, glucose uptake and

  13. Evaluating 3-D and 1-D mathematical models for mass transport in heterogeneous biofilms

    DEFF Research Database (Denmark)

    Morgenroth, Eberhard Friedrich; Eberl, H.; van Loosdrecht, M. C. M.


    Results from a three dimensional model for heterogeneous biofilms including the numerical solution of hydrodynamics were compared to simplified one dimensional models. A one dimensional model with a variable diffusion coefficient over the thickness of the biofilm was well suited to approximate av...... in a growing biofilm and in a mushroom type biofilm assuming different modes of detachment....

  14. Stochastic modeling of groundwater flow and particle transport in a 2-D heterogeneous medium by the method of conditional probabilities; Modelisation stochastique conditionnelle de l`ecoulement et du transport particulaire dans un milieu heterogene bidimensionnel

    Energy Technology Data Exchange (ETDEWEB)

    Grenier, C. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. de Mecanique et de Technologie]|[Universite Pierre et Marie Curie, 75 - Paris (France)


    The study addresses the issues of groundwater flow and particle transport in a 2-D heterogenous porous medium. We follow here the line of G. Dagan and Y. Rubin. In a series of articles these authors propose and represent the variables involves (transmissivity, head, Darcy velocity, particle position and travel time) by means of stochastic processes. The (unconditional) moments are first derived by solving the partial differential equations corresponding to a 2-D flow in a saturated medium, with no recharge. In a second step, the variances of the processes are reduced bu taking local data into account within the conditional probabilities framework. In this document we present a complete theoretical study of the method and apply it on synthetical test cases. We deal with the following matters: study the impact of different data type and configurations on the conditional estimation of the flow and transport variables; study the robustness of the model for increasing levels of heterogeneity by means of comparison with the moments obtained by Monte-Carlo simulations. The method is enlarged to weakly un-stationary flow cases (non constant transmissivity and head gradient means) and applied on synthetical test cases. (author) 80 refs.

  15. Sediment Transport on Continental Shelves: Storm Bed Formation and Preservation in Heterogeneous Sediments (United States)


    from this offshore transport is consistent with airborne laser measurements after Hurricane Ivan in the Gulf of Mexico (Robertson et al., 2007...relative contributions of resuspension and transport to storm bed generation during hurri- canes have been examined by Keen & Glenn (1998) for...conditions. /. Geophys. Res., 110, F04S15. Robertson, W., Zhang, K.Q. and Whitman, D. (2007) Hurricane-induced beach change derived from airborne laser

  16. Verification of the Advanced Nodal Method on BWR Core Analyses by Whole-Core Heterogeneous Transport Calculations

    Energy Technology Data Exchange (ETDEWEB)

    Shinya Kosaka


    Recent boiling water reactor (BWR) core and fuel designs have become more sophisticated and heterogeneous to improve fuel cycle cost, thermal margin, etc. These improvements, however, tend to lead to a strong interference effect among fuel assemblies, and it my cause some inaccuracies in the BWR core analyses by advanced nodal codes. Furthermore, the introduction of mixed-oxide (MOX) fuel will lead to a much stronger interference effect between MOX and UO{sub 2} fuel assemblies. However, the CHAPLET multiassembly characteristics transport code was developed recently to solve two-dimensional cell-heterogeneous whole-core problems efficiently, and its results can be used as reference whole-core solutions to verify the accuracy of nodal core calculations. In this paper, the results of nodal core calculations were compared with their reference whole-core transport solutions to verify their accuracy (in k{sub eff}, assembly power and pin power via pin power reconstruction) of the advanced nodal method on both UO{sub 2} and MOX BWR whole-core analyses. Especially, it was investigated if there were any significant differences in the accuracy between MOX and UO{sub 2} results.

  17. One-dimensional solute transport for uniform and varying pulse type input point source through heterogeneous medium. (United States)

    Kumar, Atul; Yadav, R R


    An analytical solution is developed for conservative solute transport in a one-dimensional heterogeneous porous medium. The solute dispersion parameter is considered uniform, while the seepage flow velocity is considered spatially dependent. Retardation factor is considered inversely proportional to square of the flow velocity. The seepage velocity flow is considered inversely proportional to the spatially dependent function. The solution is derived for two cases: the former one is for uniform pulse type input point source and the latter one is for varying pulse type input point source. The second condition is considered at the far end of the medium. It is of the second type (flux type) of homogeneous nature. Laplace transform technique (LLT) is employed to get the analytical solutions to the present problem. In the process, a new space variable is introduced. The solutions are graphically illustrated. The effects of heterogeneity of the medium on the solute transport behaviour, in the presence and absence of the source pollutant, are also studied. Laplace transformation technique is used to solve the present problems analytically.

  18. Role of geomechanically grown fractures on dispersive transport in heterogeneous geological formations

    KAUST Repository

    Nick, H. M.


    A second order in space accurate implicit scheme for time-dependent advection-dispersion equations and a discrete fracture propagation model are employed to model solute transport in porous media. We study the impact of the fractures on mass transport and dispersion. To model flow and transport, pressure and transport equations are integrated using a finite-element, node-centered finite-volume approach. Fracture geometries are incrementally developed from a random distributions of material flaws using an adoptive geomechanical finite-element model that also produces fracture aperture distributions. This quasistatic propagation assumes a linear elastic rock matrix, and crack propagation is governed by a subcritical crack growth failure criterion. Fracture propagation, intersection, and closure are handled geometrically. The flow and transport simulations are separately conducted for a range of fracture densities that are generated by the geomechanical finite-element model. These computations show that the most influential parameters for solute transport in fractured porous media are as follows: fracture density and fracture-matrix flux ratio that is influenced by matrix permeability. Using an equivalent fracture aperture size, computed on the basis of equivalent permeability of the system, we also obtain an acceptable prediction of the macrodispersion of poorly interconnected fracture networks. The results hold for fractures at relatively low density. © 2011 American Physical Society.

  19. Modeling Radicalization Phenomena in Heterogeneous Populations.

    Directory of Open Access Journals (Sweden)

    Serge Galam

    Full Text Available The phenomenon of radicalization is investigated within a mixed population composed of core and sensitive subpopulations. The latest includes first to third generation immigrants. Respective ways of life may be partially incompatible. In case of a conflict core agents behave as inflexible about the issue. In contrast, sensitive agents can decide either to live peacefully adjusting their way of life to the core one, or to oppose it with eventually joining violent activities. The interplay dynamics between peaceful and opponent sensitive agents is driven by pairwise interactions. These interactions occur both within the sensitive population and by mixing with core agents. The update process is monitored using a Lotka-Volterra-like Ordinary Differential Equation. Given an initial tiny minority of opponents that coexist with both inflexible and peaceful agents, we investigate implications on the emergence of radicalization. Opponents try to turn peaceful agents to opponents driving radicalization. However, inflexible core agents may step in to bring back opponents to a peaceful choice thus weakening the phenomenon. The required minimum individual core involvement to actually curb radicalization is calculated. It is found to be a function of both the majority or minority status of the sensitive subpopulation with respect to the core subpopulation and the degree of activeness of opponents. The results highlight the instrumental role core agents can have to hinder radicalization within the sensitive subpopulation. Some hints are outlined to favor novel public policies towards social integration.

  20. Solute transport in periodical heterogeneous porous media: Importance of observation scale and experimental sampling (United States)

    Majdalani, S.; Chazarin, J. P.; Delenne, C.; Guinot, V.


    This paper focuses on the effects of the observation scale and sampling on the dispersion of tracers in periodical heterogeneous porous media. A Model Heterogeneous Porous Medium (MHPM) with a high degree of heterogeneity was built. It consists of a preferential flow path surrounded by glass beads. 44 tracer experiments were carried out on several series of periodic MHPM to investigate the effect of the observation scale on solute dispersion. Each series was replicated several times, allowing for a statistical description of the unit transfer function of the MHPM. No significant trend was found for the dispersion coefficient as a function of the size of the MHPM. However, given the variability of the breakthrough curves from one experiment replicate to another, under-sampling might easily lead to conclude that the dispersion coefficient is variable with distance. Depending on the samples used, it would be as easy to (wrongly) detect an increasing trend as to detect a decreasing one. A confidence interval analysis of the experimental breakthrough curves in the Laplace space shows that (i) there exists a model with scale independent parameters that can describe the experimental breakthrough curves within the limits of experimental uncertainty, (ii) this model is not the advection-dispersion (AD) model, (iii) the modelling error of the AD model decreases with the number of periods, (iv) the size of the Reference Elementary Volume for the dispersion coefficient is between 10 and 20 periods. The effects of sampling prove to override those of scaling. This, with the invalidity of the AD model, leads to question attempts to calibrate and/or identify trends in the dispersion coefficient at intermediate scales from a limited number of experiment replicates.

  1. Sensitivity analyses of a colloid-facilitated contaminant transport model for unsaturated heterogeneous soil conditions. (United States)

    Périard, Yann; José Gumiere, Silvio; Rousseau, Alain N.; Caron, Jean


    Certain contaminants may travel faster through soils when they are sorbed to subsurface colloidal particles. Indeed, subsurface colloids may act as carriers of some contaminants accelerating their translocation through the soil into the water table. This phenomenon is known as colloid-facilitated contaminant transport. It plays a significant role in contaminant transport in soils and has been recognized as a source of groundwater contamination. From a mechanistic point of view, the attachment/detachment of the colloidal particles from the soil matrix or from the air-water interface and the straining process may modify the hydraulic properties of the porous media. Šimůnek et al. (2006) developed a model that can simulate the colloid-facilitated contaminant transport in variably saturated porous media. The model is based on the solution of a modified advection-dispersion equation that accounts for several processes, namely: straining, exclusion and attachement/detachement kinetics of colloids through the soil matrix. The solutions of these governing, partial differential equations are obtained using a standard Galerkin-type, linear finite element scheme, implemented in the HYDRUS-2D/3D software (Šimůnek et al., 2012). Modeling colloid transport through the soil and the interaction of colloids with the soil matrix and other contaminants is complex and requires the characterization of many model parameters. In practice, it is very difficult to assess actual transport parameter values, so they are often calibrated. However, before calibration, one needs to know which parameters have the greatest impact on output variables. This kind of information can be obtained through a sensitivity analysis of the model. The main objective of this work is to perform local and global sensitivity analyses of the colloid-facilitated contaminant transport module of HYDRUS. Sensitivity analysis was performed in two steps: (i) we applied a screening method based on Morris' elementary

  2. Microsphere transport in a fractured soil during intermittent flow: effect of microsphere sizes and soil physical heterogeneity (United States)

    Mohanty, S. K.; Bulicek, M.; Metge, D. W.; Harvey, R. W.; Boehm, A. B.; Ryan, J. N.


    The aim of this study was to evaluate the effect of soil physical heterogeneity on the transport of microspheres, used as surrogates for bacteria, during simulated intermittent rain. Artificial rainwater containing microspheres of two sizes (0.5 and 1.8 μm diameter) and bromide (1 mM) was applied to an intact soil core. After cessation of simulated rainfall, three more intermittent rainfalls were applied to the core in order to document remobilizing of the previously sequestered microspheres. Each intermittent rainfall consisted of 4 h rain preceded by 20 h pause. Water samples were collected using a 19-port grid at the bottom of the soil core to resolve the effect of core physical heterogeneity on the mobilization of microspheres. Flow was detected at 6 of 19 ports indicating occurrence of preferential flow. Microspheres preferentially migrated through fractures in soil, whereas bromide was retarded due to matrix diffusion. Bromide concentrations in the effluent declined throughout the experiment, but microsphere concentrations peaked after the pauses in rainfall. Additionally, the recovery of microspheres during intermittent flow was greatest in the port with highest flow. Thus, it appears that bromide transport is diffusion-limited, whereas the dominant mechanism for mobilization of microspheres appeared to involve shear from the advancing wetting font. Mobilization of microspheres increased with microsphere sizes presumably due to larger microspheres preferentially transported through fractures or macropores. The results of the study provide evidence that intermittent flow has potential to rapidly mobilize colloids and colloid-associated contaminants including bacteria through fractures or macropores in soil.

  3. Stochastic estimation and simulation of heterogeneities important for transport of contaminants in the unsaturated zone

    Energy Technology Data Exchange (ETDEWEB)

    Kitteroed, Nils-Otto


    The background for this thesis was the increasing risk of contamination of water resources and the requirement of groundwater protection. Specifically, the thesis implements procedures to estimate and simulate observed heterogeneities in the unsaturated zone and evaluates what impact the heterogeneities may have on the water flow. The broad goal was to establish a reference model with high spatial resolution within a small area and to condition the model using spatially frequent field observations, and the Moreppen site at Oslo`s new major airport was used for this purpose. An approach is presented for the use of ground penetrating radar in which indicator kriging is used to estimate continuous stratigraphical architecture. Kriging is also used to obtain 3D images of soil moisture. A simulation algorithm based on the Karhunen-Loeve expansion is evaluated and a modification of the Karhunen-Loeve simulation is suggested that makes it possible to increase the size of the simulation lattice. This is obtained by kriging interpolation of the eigenfunctions. 250 refs., 40 figs., 7 tabs.

  4. Using pore-scale imaging and modeling to provide new insights in multi-phase flow, transport and reaction phenomena in porous media (Invited) (United States)

    Bijeljic, B.; Andrew, M. G.; Menke, H. P.; Blunt, M. J.


    to formation of more larger ganglia; on the other hand, pore structures characterised by smaller, poorly connected pores, lead to the formation of more smaller blobs. Implications for scCO2 storage security are discussed. Finally, probably the most exciting capability of X ray imaging technique lies in its ability to image pore-scale displacements in real time. The first in-situ multiphase flow dynamic experiments during injection of supercritical CO2 in natural rock with the scanning interval of 30 seconds will be presented. Using reservoir-condition micro-flow test rig, pore-scale displacements including individual pore filling events in drainage (water/scCO2) in a carbonate rock were imaged at the Diamond Light Source synchrotron. Furthermore, the in-situ heterogeneous reaction between brine-equilibrated scCO2 and Ketton limestone at reservoir conditions has been imaged at the hours scale (with the same time resolution), where slow reaction regime was observed. The changes in porosity, permeability and, most importantly, PDFs of velocity have been characterized from the experiment and enable us to fully describe structural, flow and transport changes induced by reaction in this regime.

  5. Study of Uranium Transport Utilizing Reactive Numerical Modeling and Experimental Data from Heterogeneous Intermediate-Scale Tanks (United States)

    Rodriguez, D.; Miller, A.; Honeyman, B.


    The study of the transport of contaminants in groundwater is critical in order to mitigate risks to downstream receptors from sites where past releases of these contaminants has resulted in the degradation of the water quality of the underlying aquifer. In most cases, the fate and transport of these contaminants occurs in a chemically and physically heterogeneous environment; thereby making the prediction of the ultimate fate of these contaminants difficult. In order to better understand the fundamental processes that have the greatest effect on the transport of these contaminants, careful laboratory study must be completed in a controlled environment. Once the experimental data has been generated, the validation of numerical models may then be achieved. Questions on the management of contaminated sites may center on the long-term release (e.g., desorption, dissolution) behavior of contaminated geomedia. Data on the release of contaminants is often derived from bench-scale experiments or, in rare cases, through field-scale experiments. A central question, however, is how molecular-scale processes (e.g., bond breaking) are expressed at the macroscale. This presentation describes part of a collaborative study between the Colorado School of Mines, the USGS and Lawrence Berkeley National Lab on upscaling pore-scale processes to understanding field-scale observations. In the work described here, two experiments were conducted in two intermediate-scale tanks (2.44 m x 1.22 m x 7.6 cm and 2.44 m x 0.61 m x 7.6 cm) to generate data to quantify the processes of uranium dissolution and transport in fully saturated conditions, and to evaluate the ability of two reactive transport models to capture the relevant processes and predict U behavior at the intermediate scale. Each tank was designed so that spatial samples could be collected from the side of the tank, as well as samples from the effluent end of the tank. The larger tank was packed with a less than 2mm fraction of a

  6. Advanced diffusion processes and phenomena

    CERN Document Server

    Öchsner, Andreas; Belova, Irina


    This topical volume on Advanced Diffusion Processes and Phenomena addresses diffusion in a wider sense of not only mass diffusion but also heat diffusion in fluids and solids. Both diffusion phenomena play an important role in the characterization of engineering materials and corresponding structures. Understanding these different transport phenomena at many levels, from atomistic to macro, has therefore long attracted the attention of many researchers in materials science and engineering and related disciplines. The present topical volume captures a representative cross-section of some of the

  7. Carrier mobility in mesoscale heterogeneous organic materials: Effects of crystallinity and anisotropy on efficient charge transport (United States)

    Kobayashi, Hajime; Shirasawa, Raku; Nakamoto, Mitsunori; Hattori, Shinnosuke; Tomiya, Shigetaka


    Charge transport in the mesoscale bulk heterojunctions (BHJs) of organic photovoltaic devices (OPVs) is studied using multiscale simulations in combination with molecular dynamics, the density functional theory, the molecular-level kinetic Monte Carlo (kMC) method, and the coarse-grained kMC method, which was developed to estimate mesoscale carrier mobility. The effects of the degree of crystallinity and the anisotropy of the conductivity of donors on hole mobility are studied for BHJ structures that consist of crystalline and amorphous pentacene grains that act as donors and amorphous C60 grains that act as acceptors. We find that the hole mobility varies dramatically with the degree of crystallinity of pentacene because it is largely restricted by a low-mobility amorphous region that occurs in the hole transport network. It was also found that the percolation threshold of crystalline pentacene is relatively high at approximately 0.6. This high percolation threshold is attributed to the 2D-like conductivity of crystalline pentacene, and the threshold is greatly improved to a value of approximately 0.3 using 3D-like conductive donors. We propose essential guidelines to show that it is critical to increase the degree of crystallinity and develop 3D conductive donors for efficient hole transport through percolative networks in the BHJs of OPVs.

  8. Imaging geochemical heterogeneities using inverse reactive transport modeling: An example relevant for characterizing arsenic mobilization and distribution

    DEFF Research Database (Denmark)

    Fakhreddine, Sarah; Lee, Jonghyun; Kitanidis, Peter K.


    The spatial distribution of reactive minerals in the subsurface is often a primary factor controlling the fate and transport of contaminants in groundwater systems. However, direct measurement and estimation of heterogeneously distributed minerals are often costly and difficult to obtain. While...... groundwater parameters. Specifically, we simulate the mobilization of arsenic via kinetic oxidative dissolution of As-bearing pyrite due to dissolved oxygen in the ambient groundwater, which is an important mechanism for arsenic release in groundwater both under natural conditions and engineering applications...... such as managed aquifer recharge and recovery operations. The modeling investigation is carried out at various scales and considers different flow-through domains including (i) a ID lab-scale column (SO cm), (ii) a 2D lab-scale setup (60 cm x 30 cm) and (iii) a 2D field scale domain (20 nix 4 m). In these setups...

  9. Transport and deposition of polymer-modified Fe0 nanoparticles in 2-D heterogeneous porous media: effects of particle concentration, Fe0 content, and coatings. (United States)

    Phenrat, Tanapon; Cihan, Abdullah; Kim, Hye-Jin; Mital, Menka; Illangasekare, Tissa; Lowry, Gregory V


    Concentrated suspensions of polymer-modified Fe(0) nanoparticles (NZVI) are injected into heterogeneous porous media for groundwater remediation. This study evaluated the effect of porous media heterogeneity and the dispersion properties including particle concentration, Fe(0) content, and adsorbed polymer mass and layer thickness which are expected to affect the delivery and emplacement of NZVI in heterogeneous porous media in a two-dimensional (2-D) cell. Heterogeneity in hydraulic conductivity had a significant impact on the deposition of NZVI. Polymer modified NZVI followed preferential flow paths and deposited in the regions where fluid shear is insufficient to prevent NZVI agglomeration and deposition. NZVI transported in heterogeneous porous media better at low particle concentration (0.3 g/L) than at high particle concentrations (3 and 6 g/L) due to greater particle agglomeration at high concentration. High Fe(0) content decreased transport during injection due to agglomeration promoted by magnetic attraction. NZVI with a flat adsorbed polymeric layer (thickness ∼30 nm) could not be transported effectively due to pore clogging and deposition near the inlet, while NZVI with a more extended adsorbed layer thickness (i.e., ∼70 nm) were mobile in porous media. This study indicates the importance of characterizing porous media heterogeneity and NZVI dispersion properties as part of the design of a robust delivery strategy for NZVI in the subsurface.

  10. Nonideal transport of reactive contaminants in heterogeneous porous media: 7. distributed-domain model incorporating immiscible-liquid dissolution and rate-limited sorption/desorption. (United States)

    Zhang, Zhihui; Brusseau, Mark L


    The purpose of this work is to present a distributed-domain mathematical model incorporating the primary mass-transfer processes that mediate the transport of immiscible organic liquid constituents in water-saturated, locally heterogeneous porous media. Specifically, the impact of grain/pore-scale heterogeneity on immiscible-liquid dissolution and sorption/desorption is represented in the model by describing the system as comprising a continuous distribution of mass-transfer domains. With this conceptualization, the distributions of the initial dissolution rate coefficient and the sorption/desorption rate coefficient are represented as probability density functions. Several sets of numerical experiments are conducted to examine the effects of heterogeneous dissolution and sorption/desorption on contaminant transport and elution. Four scenarios with different combinations of uniform/heterogeneous rate-limited dissolution and uniform/heterogeneous rate-limited sorption/desorption are evaluated. The results show that both heterogeneous rate-limited sorption/desorption and heterogeneous rate-limited dissolution can significantly increase the time or pore volumes required to elute immiscible-liquid constituents from a contaminated porous medium. However, sorption/desorption has minimal influence on elution behavior until essentially all of the immiscible liquid has been removed. For typical immiscible-liquid constituents that have relatively low sorption, the asymptotic elution tailing produced by heterogeneous rate-limited sorption/desorption begins at effluent concentrations that are several orders of magnitude below the initial steady-state concentrations associated with dissolution of the immiscible liquid. Conversely, the enhanced elution tailing associated with heterogeneous rate-limited dissolution begins at concentrations that are approximately one-tenth of the initial steady-state concentrations. Hence, dissolution may generally control elution behavior of

  11. X-ray Spectroscopy and Imaging as Multiscale Probes of Intercalation Phenomena in Cathode Materials (United States)

    Horrocks, Gregory A.; De Jesus, Luis R.; Andrews, Justin L.; Banerjee, Sarbajit


    Intercalation phenomena are at the heart of modern electrochemical energy storage. Nevertheless, as out-of-equilibrium processes involving concomitant mass and charge transport, such phenomena can be difficult to engineer in a predictive manner. The rational design of electrode architectures requires mechanistic understanding of physical phenomena spanning multiple length scales, from atomistic distortions and electron localization at individual transition metal centers to phase inhomogeneities and intercalation gradients in individual particles and concentration variances across ensembles of particles. In this review article, we discuss the importance of the electronic structure in mediating electrochemical storage and mesoscale heterogeneity. In particular, we discuss x-ray spectroscopy and imaging probes of electronic and atomistic structure as well as statistical regression methods that allow for monitoring of the evolution of the electronic structure as a function of intercalation. The layered α-phase of V2O5 is used as a model system to develop fundamental ideas on the origins of mesoscale heterogeneity.

  12. Impact of bimodal textural heterogeneity and connectivity on flow and transport through unsaturated mine waste rock (United States)

    Appels, Willemijn M.; Ireson, Andrew M.; Barbour, S. Lee


    Mine waste rock dumps have highly variable flowpaths caused by contrasting textures and geometry of materials laid down during the 'plug dumping' process. Numerical experiments were conducted to investigate how these characteristics control unsaturated zone flow and transport. Hypothetical profiles of inner-lift structure were generated with multiple point statistics and populated with hydraulic parameters of a finer and coarser material. Early arrival of water and solutes at the bottom of the lifts was observed after spring snowmelt. The leaching efficiency, a measure of the proportion of a resident solute that is flushed out of the rock via infiltrating snowmelt or rainfall, was consistently high, but modified by the structure and texture of the lift. Under high rates of net percolation during snowmelt, preferential flow was generated in coarse textured part of the rock, and solutes in the fine textured parts of the rock remained stagnant. Under lower rates of net percolation during the summer and fall, finer materialswere flushed too, and the spatial variability of solute concentration in the lift was reduced. Layering of lifts leads to lower flow rates at depth, minimizing preferential flow and increased leaching of resident solutes. These findings highlight the limited role of large scale connected geometries on focusing flow and transport under dynamic surface net percolation conditions. As such, our findings agree with recent numerical results from soil studies with Gaussian connected geometries as well as recent experimental findings, emphasizing the dominant role of matrix flow and high leaching efficiency in large waste rock dumps.

  13. Transport theory calculation for a heterogeneous multi-assembly problem by characteristics method with direct neutron path linking technique

    Energy Technology Data Exchange (ETDEWEB)

    Kosaka, Shinya; Saji, Etsuro [In-Core Fuel Management System Department, Toden Software, Inc., Tokyo (Japan)


    A characteristics transport theory code, CHAPLET, has been developed for the purpose of making it practical to perform a whole LWR core calculation with the same level of calculational model and accuracy as that of an ordinary single assembly calculation. The characteristics routine employs the CACTUS algorithm for drawing ray tracing lines, which assists the two key features of the flux solution in the CHAPLET code. One is the direct neutron path linking (DNPL) technique which strictly connects angular fluxes at each assembly interface in the flux solution separated between assemblies. Another is to reduce the required memory storage by sharing the data related to ray tracing among assemblies with the same configuration. For faster computation, the coarse mesh rebalance (CMR) method and the Aitken method were incorporated in the code and the combined use of both methods showed the most promising acceleration performance among the trials. In addition, the parallelization of the flux solution was attempted, resulting in a significant reduction in the wall-clock time of the calculation. By all these efforts, coupled with the results of many verification studies, a whole LWR core heterogeneous transport theory calculation finally became practical. CHAPLET is thought to be a useful tool which can produce the reference solutions for analyses of an LWR (author)

  14. Heterogeneous IT Knowledge of Students: the Didactic Approach how to meet it in the Interdisciplinary Course Program Intelligent Transport Systems

    Directory of Open Access Journals (Sweden)

    Harald Wahl


    Full Text Available At the University of Applied Sciences (UAS Technikum Wien, Intelligent Transport System is a highly interdisciplinary Bachelor's degree program. Its curriculum covers several mainly technical oriented disciplines. Especially the IT courses account for the high drop-out rate of the course program. Students come with different IT knowledge depending on the one hand on their previous school education and on the other hand depending on their personal interest in IT topics. Normally, for students, IT is not the number one reason for choosing this program. Nevertheless, IT is extremely important as it interacts with all other disciplines. Especially the heterogeneity of the IT knowledge made it necessary to rethink the way of teaching. The paper describes the new didactic approach of the IT courses in the course program Intelligent Transport Systems. The new approach faces the students' difficulties and tries to overcome the varying pre-knowledge of students. Furthermore, it tries to increase students' motivation by paying particular attention to the students' assumed interests.

  15. A DFN-based High Performance Computing Approach to the Simulation of Radionuclide Transport in Mineralogically Heterogeneous Fractured Rocks (United States)

    Gylling, B.; Trinchero, P.; Molinero, J.; Deissmann, G.; Svensson, U.; Ebrahimi, H.; Hammond, G. E.; Bosbach, D.; Puigdomenech, I.


    Geological repositories for nuclear waste are based multi-barrier concepts using engineered and natural barriers. In fractured crystalline rocks, the efficiency of the host rock as transport barrier is related to the processes: advection along fractures, diffusion into the rock matrix and retention onto the available sorption sites. Anomalous matrix penetration profiles were observed in experiments (i.e. REPRO carried out by Posiva at the ONKALO underground facility in Finland and the Long Term Sorption Diffusion Experiment, LTDE-SD, carried out by SKB at the Äspö Hard Rock Laboratory in Sweden). The textural and mineralogical heterogeneity of the rock matrix was offered as plausible explanation for these anomalous penetration profiles. The heterogeneous structure of the rock matrix was characterised at the grain-scale using a micron-scale Discrete Fracture Network (DFN), which is then represented onto a micron-scale structured grid. Matrix fracture free volumes are identified as reactive biotite-bearing grains whereas the rest of the matrix domain constitutes the inter-granular regions. The reactive transport problem mimics the ingress of cesium along a single transmissive fracture. Part of the injected mass diffuses into the matrix where it might eventually sorb onto the surface of reactive grains. The reactive transport calculations are carried out using iDP (interface between DarcyTools and PFLOTRAN). The generation of the DFN is done by DarcyTools, which also takes care of solving the groundwater flow problem. Computed Darcy velocities are extracted and used as input for PFLOTRAN. All the simulation runs are carried out on the supercomputer JUQUEEN at the Jülich Supercomputing Centre. The results are compared with those derived with an alternative model, where biotite abundance is averaged over the whole matrix volume. The analysis of the cesium breakthrough computed at the fracture outlet shows that the averaged model provides later first-arrival time

  16. Joint hydrogeological and hydrogeophysical models to map subsurface heterogeneity and to model transport processes (United States)

    Cattaneo, Laura; Giudici, Mauro; De Franco, Roberto; Mele, Mauro; Vassena, Chiara


    Hydraulic conductivity and electrical resistivity of the alluvial sediments depend, among the others, on textures and soil saturation. Characterization of the subsurface heterogeneity and monitoring the dynamics of groundwater can be accomplished by the collection of geoelectrical and hydraulic data and by the joint modeling of the corresponding physical processes. A research project, during which it has been developing an interpretative tool that profits from DC geoelectrical and hydraulic measurements, aims to provide a further step towards this objective. Two original computer codes, both based on conservative finite differences schemes, have been developed to solve the hydrological (YAGMOD) and the geoelectrical (YAELMOD) forward problems. The subsurface is considered to be subdivided in hydro-geo-bodies, which are regions occupied by geological materials (hydro-geo-facies, HGF) which share the same geoelectrical and hydrodynamic characteristics, namely phenomenological laws that relate electrical resistivity and hydraulic conductivity to texture, soil saturation and pore water conductivity, through specific phenomenological parameters for each HGF. If the spatial distribution of HGFs is estimated from a collection of lithological data (e.g. boreholes) and if the spatial distribution of soil saturation and pore water conductivity is known, then the hydraulic conductivity and electrical resistivity fields could be reconstructed. The developed interpretative tool could then apply an iterative procedure that repeatedly solves the hydraulic and electrical forward problem for different stress condition of the aquifer by changing the estimated HGF parameters, as a basic step to match experimental data with model outcomes, by the application of an approach based on the Kalman filter. In particular the goal of this presentation is to assess the sensitivity of some of the model features on the results and on the capability of the interpretative tool. The focus is on a

  17. Modelling radionuclide transport in highly heterogeneous media and under variable hydrochemical conditions using a "dynamic Kd" approach (United States)

    Trinchero, Paolo; Painter, Scott; Ebrahimi, Hedieh; Koskinen, Lasse; Molinero, jorge; Selroos, Jan-Olof


    Due to the high heterogeneity of fractured media and the ubiquitous lack of a complete site characterization, deterministic simulations of radionuclide transport in fractured rocks are notoriously highly uncertain. This uncertainty is usually addressed using stochastic methods; e.g. the connectivity structure of the medium is described using multiple realizations of Discrete Fracture Networks (DFN), which are then combined to particle tracking simulations. In these formulations, many complex geochemical retention processes are typically lumped into a single parameter: the distribution coefficient (Kd). This approach relies on an important assumption: the Kd values are constant in time. This hypothesis is critical under long-term geochemical changes as it is known that the distribution coefficient depends on the pH, redox conditions and major chemistry of the system. In this work, we present a novel methodology that combines the robustness of stochastic methods with an explicit description of water-solute-rock interaction processes. The reconciliation of all these is achieved by using a dynamic Kd approach. The hydrogeochemical evolution of the site of study is first computed using long-term and large-scale mechanistic reactive transport simulations. The simulated hydrochemical conditions are then used to generate a complete database of Kd values, which represent the hydrochemical conditions in every position and time of the model domain. Then, MARFA (Painter and Mancillas, 2009) is used to carry out Time Domain Random Walk (TDRW) simulations of radionuclide transport. In these simulations, Kd values are dynamically updated using the afore-mentioned database. The results (i.e. radionuclide breakthrough curves) bring the signature of the underlying changes in the background geochemistry.

  18. Transport phenomena in the close-spaced sublimation deposition process for manufacture of large-area cadmium telluride photovoltaic panels: Modeling and optimization (United States)

    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

  19. Heterogeneity in the expression and subcellular localization of POLYOL/MONOSACCHARIDE TRANSPORTER genes in Lotus japonicus.

    Directory of Open Access Journals (Sweden)

    Lu Tian

    Full Text Available Polyols can serve as a means for the translocation of carbon skeletons and energy between source and sink organs as well as being osmoprotective solutes and antioxidants which may be involved in the resistance of some plants to biotic and abiotic stresses. Polyol/Monosaccharide transporter (PLT proteins previously identified in plants are involved in the loading of polyols into the phloem and are reported to be located in the plasma membrane. The functions of PLT proteins in leguminous plants are not yet clear. In this study, a total of 14 putative PLT genes (LjPLT1-14 were identified in the genome of Lotus japonicus and divided into 4 clades based on phylogenetic analysis. Different patterns of expression of LjPLT genes in various tissues were validated by qRT-PCR analysis. Four genes (LjPLT3, 4, 11, and 14 from clade II were expressed at much higher levels in nodule than in other tissues. Moreover, three of these genes (LjPLT3, 4, and 14 showed significantly increased expression in roots after inoculation with Mesorhizobium loti. Three genes (LjPLT1, 3, and 9 responded when salinity and/or osmotic stresses were applied to L. japonicus. Transient expression of GFP-LjPLT fusion constructs in Arabidopsis and Nicotiana benthamiana protoplasts indicated that the LjPLT1, LjPLT6 and LjPLT7 proteins are localized to the plasma membrane, but LjPLT2 (clade IV, LjPLT3, 4, 5 (clade II and LjPLT8 (clade III proteins possibly reside in the Golgi apparatus. The results suggest that members of the LjPLT gene family may be involved in different biological processes, several of which may potentially play roles in nodulation in this nitrogen-fixing legume.

  20. Heterogeneity in Extracellular Polymeric Substances Production and its Effects on the Transport and Attachment of Trichloroethene Degrading Toluene Oxidizing Bacteria (United States)

    Putthividhya, A.; Abriola, L. M.; Kukor, J. J.


    The role of extracellular polymeric substances (EPS) heterogeneity in microbial transport and retention was investigated for pure cultures of trichloroethene (TCE) degrading toluene oxidizing bacteria. A wildtype and a mutant strain of Ralstonia pickettii were employed in sand column experiments, based upon their ability to metabolize alkyl aromatic hydrocarbons and cometabolize TCE by a toluene-3-monooxygenase (T3MO) enzyme system. These wildtype and mutant strains are identical, except that the TbuX protein is knocked out in the latter, resulting in less EPS synthesis. A pulse of 3H radiolabeled cell-EPS suspension was introduced to saturated packed sand columns under steady flow conditions. Biomass and EPS were quantified in the influent, effluent, and within the porous medium. Experimental results indicate that increased EPS enhanced bacterial retention and reduced detachment. While biomass deposition (mass/g sand) declined, EPS (mg/g sand) increased with travel distance along the column. EPS mass balance calculations suggest that EPS were synthesized by surface-associated bacteria within the column. The biomass-normalized EPS along the column ranged from values that were fairly consistent with those found under free-living conditions (near the column entrance) to five-fold increases (near the column outlet), suggesting that most EPS synthesis took place in microbes deposited near the column outlet. Flow cytometric results revealed no significant change in average cell size within the two day starvation period. However, cell influent was comprised of at least two subpopulations, as assessed through differences in fluorescence intensity. Additionally, a better prediction of the observed microbial deposition pattern was achieved with a model that incorporates a power-law distribution for the particle-collector deposition rate coefficients, consistent with a variation of attachment properties within the population. This observed microbial heterogeneity could also

  1. Visualizing Advective and Diffusive Phenomena in Fluid-Rock Interaction using Thermochromic Materials (United States)

    Heinle, B.; Cardiff, M. A.


    The presence of fractures plays an essential role in hydrogeologic transport, as well as geothermal and hydrocarbon industries, as fractures introduce new pathways for flow and transport in host rocks. Transport through these features is often highly non-Fickian, due to the combination of both heterogeneous advection and matrix diffusion. Fracture aperture distributions and contact areas control the ability of fluids to flow through a fracture, and to interact with host rock. The heterogeneous nature of these fracture apertures often lead to preferential fluid pathways that control the prevalence of advective and diffusive processes within the fracture network. To understand how preferential fluid pathways affect these transport processes in detail, an innovative approach is introduced for visualizing advective and diffusive phenomena through the use of thermochromic liquid crystals (TLCs). An artificial fracture with the ability to have its surface roughness altered is constructed and heterogeneous flow and diffusion of heat is observed directly using these TLCs. The surfaces are digitized and simulated in COMSOL Multiphysics where particle tracing is used to determine arrival time curves in the absence of host rock diffusion. The resulting combination of the visual results from lab experiments and particle statistics from the computer model provide a unique method for assessing the impact of both heterogeneous advection and matrix-diffusion on tracer breakthrough in fractures, across a variety of fracture geometries. Figure 1. Image of advective (left) and diffusive (right) phenomena occurring simultaneously as fluid flows through the artificial fracture.

  2. Implications of heterogeneity on transport simulations at large scale: the Morroa aquifer case

    Directory of Open Access Journals (Sweden)

    Anibal Jose Pérez-García


    Full Text Available El acuífero Morroa, localizado en el departamento de Sucre (Colombia, representa la única fuente de suministro de agua potable de cerca de 500.000 habitantes que incluyen la totalidad de los habitantes de la capital del departamento Sincelejo. Aunque se han desarrollado muchos estudios en esta zona que incluyen la recolección de gran cantidad de información relacionada con niveles piezométricos, información estratigráfica, pruebas de bombeo, esta información es difusa, heterogénea y fraccionada. La incertidumbre asociada a esta información afecta cualquier intento de cuantificar la respuesta del acuífero, por esta razón el punto de partida de esta investigación es el desarrollo de una metodología capaz de integrar todas las variables en un modelo conceptual. Para considerar la incertidumbre se generaron múltiples realizaciones del acuífero de tal manera que todas respetan las propiedades estadísticas de la información disponible. Para generar estas realizaciones se utilizaron dos metodologías: (1 SISIM, que es un método basado en estadísticas de dos puntos (semivariograma, y (2 SNESIM, que es un algoritmo basado en el concepto de imágenes de entrenamiento (estadística de puntos múltiples. Resultados de las simulaciones muestran la gran capacidad de este último para reproducir geometrías curvilíneas complejas. En una segunda fase, se desarrollaron simulaciones de flujo y transporte de contaminantes de una manera integrada usando los dos modelos conceptuales obtenidos a través de las dos aproximaciones geoestadísticas. Condiciones de flujo estacionario y un contaminante conservativo fueron asumidos para todas las simulaciones. Los resultados obtenidos muestran una influencia notable de la heterogeneidad en general, así como una gran sensibilidad al método geoestadístico usado para generar la heterogeneidad. Las diferencias observadas tendrían un gran efecto en el diseño de políticas de manejo integral del recurso

  3. Numerical validation of a Eulerian hydrochemical code using a 1D multisolute mass transport system involving heterogeneous kinetically controlled reactions (United States)

    Gérard, F.; Clément, A.; Fritz, B.


    the convergence and to extend the numerical test to mixed advective-dispersive mass transport. However, the skewness factor involves numerical oscillations that prevent to compute different grid spacing. The use of a different chemically controlled time step constraint in both calculations induces some inconsistencies into the validation tests. This numerical validation method may be applied as well as to check a thermo-kinetic hydrochemical finite element based code, from a 1D heterogeneous systems, and 2D-3D systems provided that they are designed so as to be 1D equivalent. A one-step algorithm and the use of a numerical reference coming from the Eulerian code to be tested ensure the potential success (accuracy) of the numerical validation method.

  4. Analysis of flashing and swelling phenomena in tanks of nuclear power plants; the importance of bubble growth dynamics and bubble transport models with size tracking

    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:; Munoz C, J.L. [Department of Chemical and Nuclear Engineering, Polytechnic University of Valencia, Camino de Vera 14, 46022 Valencia (Spain)


    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.

  5. Intratumoral Heterogeneous F 18 Fluorodeoxyglucose Uptake Corresponds with Glucose Transporter 1 and Ki-67 Expression in a Case of Krukenberg Tumor: Localization of Intratumoral Hypermetabolic Focus by Fused PET/MR

    Energy Technology Data Exchange (ETDEWEB)

    Im, Hyung Jun; Kim, Youg il; Kim, Woo Ho; Kim, Seung Hyup; Kang, Keon Wook [Seoul National Univ. College of Medicine, Seoul (Korea, Republic of)


    The expression of glucose transporters (Glut 1, Glut 3), Hexokinase II, and Ki-67 has been proposed to explain intratumoral heterogeneous F-18 fluorodeoxyglucose (FDG) uptake. We report a case of Krukenberg tumor with intratumoral heterogeneous FDG uptake which corresponded well with the expression tomography (PET)/magnetic resonance (MR) imaging was helpful for localizing the metabolically active area in the tumor specimen. This report elucidates the relationship between the intratumoral heterogeneous FDG uptake and biologic heterogeneity, and shows the usefulness of PET/MR in research on intratumoral heterogeneity.

  6. Mathematical modeling of liquid/liquid hollow fiber membrane contactor accounting for interfacial transport phenomena: Extraction of lanthanides as a surrogate for actinides

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, J.D.


    This report is divided into two parts. The second part is divided into the following sections: experimental protocol; modeling the hollow fiber extractor using film theory; Graetz model of the hollow fiber membrane process; fundamental diffusive-kinetic model; and diffusive liquid membrane device-a rigorous model. The first part is divided into: membrane and membrane process-a concept; metal extraction; kinetics of metal extraction; modeling the membrane contactor; and interfacial phenomenon-boundary conditions-applied to membrane transport.

  7. A three-dimensional hyporheic model of River Bure: The role of streambed and morphological heterogeneity and estimation of reactive nitrogen transport. (United States)

    Gokdemir, C.; Tonina, D.; Heppell, C. M.; Copty, N. K.; Bellin, A.


    The hyporheic zone (HZ) is the near surface streambed sediment mostly saturated with stream water. This exchange causes unique biogeochemical conditions that can attenuate contaminants from either upstream surface water or groundwater under gaining and losing conditions. Hyporheic exchange often results from near-bed total pressure gradients due to channel morphology and alluvium hydraulic conductivity. Here we investigated these effects on a 300 m long morphologically complex low-gradient reach of the River Bure (UK). The reach presents three morphologically different sections: meander, straight and pool-dominated. Streambed sediment stratigraphic analysis showed facies of clay, silt, fine sand, and gravel, from which a set of 227 heterogeneous distributions of the hydraulic conductivity were developed along with an equivalent homogenous case. Results of the simulated hyporheic flow indicate that morphologic effect overwhelms that of discharge and, on some cases, alluvium heterogeneity on controlling the hyporheic residence time distribution (RTD). Furthermore, heterogeneity causes an increase in the variability of redox conditions within the HZ. Temporal characteristics of the hyporheic zone were observed to change due to morphological features and, consequently, RTDs were examined for each distinct morphological section separately. The average of the median residence times estimated from RTDs of heterogeneous realizations are similar for the meandering and the straight portions of the reach (161 h the former and 165 h the latter), but much lower in the pool-dominated zone (50 h). This raised a question if the temporal diversity of HZs has an effect on overall redox conditions and on the nitrogen cycle. The proposed work has the potential to depict different residence time zones and biogeochemical reactivity in heterogeneous sediments, and their effects on transport of reactive nitrogen species. Furthermore, our results shed some light on the functionality of

  8. Multi-Regional Reactive Transport Due to Strong Anisotropy in Unsaturated Soils with Evolving Scales of Heterogeneity

    Energy Technology Data Exchange (ETDEWEB)

    Xinghua Mo


    Anisotropic and heterogeneous flow in unsaturated porous media is dependent on saturation conditions, and currently there exist limited options that adequately model this phenomenon. The phenomenon of lateral spreading commonly attributed to anisotropy can move contaminants beyond compliance boundaries at unexpected velocitites essentially bypassing large regions of the subsurface.

  9. An Innovative Three-Dimensional Heterogeneous Coarse-Mesh Transport Method for Advanced and Generation IV Reactor Core Analysis and Design

    Energy Technology Data Exchange (ETDEWEB)

    Farzad Rahnema


    This project has resulted in a highly efficient method that has been shown to provide accurate solutions to a variety of 2D and 3D reactor problems. The goal of this project was to develop (1) an accurate and efficient three-dimensional whole-core neutronics method with the following features: based sollely on transport theory, does not require the use of cross-section homogenization, contains a highly accurate and self-consistent global flux reconstruction procedure, and is applicable to large, heterogeneous reactor models, and to (2) create new numerical benchmark problems for code cross-comparison.

  10. Application of the statistical rate theory of interfacial transport to investigate the kinetics of divalent metal ion adsorption onto the energetically heterogeneous surfaces of oxides and activated carbons (United States)

    Piasecki, W.; Rudziński, W.


    Divalent metal cation adsorption from solution onto oxides or activated carbons can be described by the Surface Complexation Model (SCM). We assumed that the adsorbent surface is strongly energetically heterogeneous and derived the adsorption isotherm using rectangular distribution of adsorption energy and condensation approximation for the local isotherm equation. Assuming additionally that the bulk concentration of divalent metal ion is low and does not change considerably during the adsorption process and next applying the Statistical Rate Theory of Interfacial Transport (SRT) we derived the Elovich equation—the experimental formula describing adsorption kinetics.

  11. An analytical approach for a nodal formulation of a two-dimensional fixed-source neutron transport problem in heterogeneous medium

    Energy Technology Data Exchange (ETDEWEB)

    Basso Barichello, Liliane; Dias da Cunha, Rudnei [Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil). Inst. de Matematica; Becker Picoloto, Camila [Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica; Tres, Anderson [Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Matematica Aplicada


    A nodal formulation of a fixed-source two-dimensional neutron transport problem, in Cartesian geometry, defined in a heterogeneous medium, is solved by an analytical approach. Explicit expressions, in terms of the spatial variables, are derived for averaged fluxes in each region in which the domain is subdivided. The procedure is an extension of an analytical discrete ordinates method, the ADO method, for the solution of the two-dimensional homogeneous medium case. The scheme is developed from the discrete ordinates version of the two-dimensional transport equation along with the level symmetric quadrature scheme. As usual for nodal schemes, relations between the averaged fluxes and the unknown angular fluxes at the contours are introduced as auxiliary equations. Numerical results are in agreement with results available in the literature.

  12. Impacts of physical and chemical aquifer heterogeneity on basin-scale solute transport: Vulnerability of deep groundwater to arsenic contamination in Bangladesh (United States)

    Michael, Holly A.; Khan, Mahfuzur R.


    Aquifer heterogeneity presents a primary challenge in predicting the movement of solutes in groundwater systems. The problem is particularly difficult on very large scales, across which permeability, chemical properties, and pumping rates may vary by many orders of magnitude and data are often sparse. An example is the fluvio-deltaic aquifer system of Bangladesh, where naturally-occurring arsenic (As) exists over tens of thousands of square kilometers in shallow groundwater. Millions of people in As-affected regions rely on deep (≥150 m) groundwater as a safe source of drinking water. The sustainability of this resource has been evaluated with models using effective properties appropriate for a basin-scale contamination problem, but the extent to which preferential flow affects the timescale of downward migration of As-contaminated shallow groundwater is unknown. Here we embed detailed, heterogeneous representations of hydraulic conductivity (K), pumping rates, and sorptive properties (Kd) within a basin-scale numerical groundwater flow and solute transport model to evaluate their effects on vulnerability and deviations from simulations with homogeneous representations in two areas with different flow systems. Advective particle tracking shows that heterogeneity in K does not affect average travel times from shallow zones to 150 m depth, but the travel times of the fastest 10% of particles decreases by a factor of ∼2. Pumping distributions do not strongly affect travel times if irrigation remains shallow, but increases in the deep pumping rate substantially reduce travel times. Simulation of advective-dispersive transport with sorption shows that deep groundwater is protected from contamination over a sustainable timeframe (>1000 y) if the spatial distribution of Kd is uniform. However, if only low-K sediments sorb As, 30% of the aquifer is not protected. Results indicate that sustainable management strategies in the Bengal Basin should consider impacts of both

  13. Nonequilibrium Phenomena in Plasmas

    CERN Document Server

    Sharma, A Surjalal


    The complexity of plasmas arises mainly from their inherent nonlinearity and far from equilibrium nature. The nonequilibrium behavior of plasmas is evident in the natural settings, for example, in the Earth's magnetosphere. Similarly, laboratory plasmas such as fusion bottles also have their fair share of complex behavior. Nonequilibrium phenomena are intimately connected with statistical dynamics and form one of the growing research areas in modern nonlinear physics. These studies encompass the ideas of self-organization, phase transition, critical phenomena, self-organized criticality and turbulence. This book presents studies of complexity in the context of nonequilibrium phenomena using theory, modeling, simulations, and experiments, both in the laboratory and in nature.

  14. Nonlinear surface electromagnetic phenomena

    CERN Document Server

    Ponath, H-E


    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

  15. Science and Paranormal Phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Noyes, H. Pierre


    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.

  16. Ultrashort Laser Pulse Phenomena

    CERN Document Server

    Diels, Jean-Claude


    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

  17. Dropout Phenomena at Universities

    DEFF Research Database (Denmark)

    Larsen, Michael Søgaard; Kornbeck, Kasper Pihl; Kristensen, Rune

    Dropout from university studies comprises a number of complex phenomena with serious complex consequences and profound political attention. Further analysis of the field is, therefore, warranted. Such an analysis is offered here as a systematic review which gives answers based on the best possible...... evidence found in the research field comprised by the three review questions to be addressed. The aims of this systematic review can, thus, be summarized like this: Which answers can be offered from research in relation to the following questions: What is dropout from university studies? Why do...... such dropout phenomena occur at universities? What can be done by the universities to prevent or reduce such dropout phenomena?...

  18. Dual control of flow field heterogeneity and immobile porosity on non‐Fickian transport in Berea sandstone

    National Research Council Canada - National Science Library

    Gjetvaj, Filip; Russian, Anna; Gouze, Philippe; Dentz, Marco


    .... Here we investigate non‐Fickian transport using high‐resolution 3‐D X‐ray microtomographic images of Berea sandstone containing microporous cement with pore size below the setup resolution...

  19. Heights integrated model as instrument for simulation of hydrodynamic, radiation transport, and heat conduction phenomena of laser-produced plasma in EUV applications.

    Energy Technology Data Exchange (ETDEWEB)

    Sizyuk, V.; Hassanein, A.; Morozov, V.; Sizyuk, T.; Mathematics and Computer Science


    The HEIGHTS integrated model has been developed as an instrument for simulation and optimization of laser-produced plasma (LPP) sources relevant to extreme ultraviolet (EUV) lithography. The model combines three general parts: hydrodynamics, radiation transport, and heat conduction. The first part employs a total variation diminishing scheme in the Lax-Friedrich formulation (TVD-LF); the second part, a Monte Carlo model; and the third part, implicit schemes with sparse matrix technology. All model parts consider physical processes in three-dimensional geometry. The influence of a generated magnetic field on laser plasma behavior was estimated, and it was found that this effect could be neglected for laser intensities relevant to EUV (up to {approx}10{sup 12} W/cm{sup 2}). All applied schemes were tested on analytical problems separately. Benchmark modeling of the full EUV source problem with a planar tin target showed good correspondence with experimental and theoretical data. Preliminary results are presented for tin droplet- and planar-target LPP devices. The influence of three-dimensional effects on EUV properties of source is discussed.

  20. Hydromagnetic transport phenomena from a stretching or shrinking nonlinear nanomaterial sheet with Navier slip and convective heating: A model for bio-nano-materials processing

    Energy Technology Data Exchange (ETDEWEB)

    Uddin, M.J., E-mail: [Department of Mathematics, American International University-Bangladesh, Banani Dhaka 1213 (Bangladesh); Bég, O. Anwar [Gort Engovation Research (Propulsion/Biomechanics), Gabriel' s Wing House, 15 Southmere Ave., Bradford, BD7 3NU England (United Kingdom); Amin, N. [Department of Mathematical Sciences, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Johor (Malaysia)


    Steady two-dimensional magnetohydrodynamic laminar free convective boundary layer slip flow of an electrically conducting Newtonian nanofluid from a translating stretching/shrinking sheet in a quiescent fluid is studied. A convective heating boundary condition is incorporated. The transport equations along with the boundary conditions are first converted into dimensionless form and following the implementation of a linear group of transformations, the similarity governing equations are developed. The transformed equations are solved numerically using the Runge–Kutta–Fehlberg fourth fifth order method from Maple. Validation of the Maple solutions is achieved with previous non-magnetic published results. The effects of the emerging thermophysical parameters; namely, stretching/shrinking, velocity slip, magnetic field, convective heat transfer and buoyancy ratio parameters, on the dimensionless velocity, temperature and concentration (nanoparticle fraction) are depicted graphically and interpreted at length. It is found that velocity increases whilst temperature and concentration reduce with the velocity slip. Magnetic field causes to reduce velocity and enhances temperature and concentration. Velocity, temperature as well as concentration rises with convective heating parameter. The study is relevant to the synthesis of bio-magnetic nanofluids of potential interest in wound treatments, skin repair and smart coatings for biological devices. - Highlights: • This paper analyses MHD slip flow of nofluid with convective boundary conditions. • Group method is used to transform governing equations into similarity equations. • The Runge–Kutta–Fehlberg method is used for numerical computations. • The study is relevant to synthesis of bio-magnetic nanofluids.

  1. A random walk solution for modeling solute transport with network reactions and multi-rate mass transfer in heterogeneous systems: Impact of biofilms (United States)

    Henri, Christopher V.; Fernàndez-Garcia, Daniel


    The interplay between the spatial variability of the aquifer hydraulic properties, mass transfer due to sub-grid heterogeneity and chemical reactions often complicates reactive transport simulations. It is well documented that hydro-biochemical properties are ubiquitously heterogeneous and that diffusion and slow advection at the sub-grid scale typically leads to the conceptualization of an aquifer as a multi-porosity system. Within this context, chemical reactions taking place in mobile/immobile water regions can be substantially different between each other. This paper presents a particle-based method that can efficiently simulate heterogeneity, network reactions and multi-rate mass transfer. The approach is based on the development of transition probabilities that describe the likelihood that particles belonging to a given species and mobile/immobile domain at a given time will be transformed into another species and mobile/immobile domain afterwards. The joint effect of mass transfer and sequential degradation is shown to be non-trivial. A characteristic rebound of degradation products can be observed. This late rebound of concentrations is not driven by any change in the flow regime (e.g., pumping ceases in the pump-and-treat remediation strategy) but due to the natural interplay between mass transfer and chemical reactions. To illustrate that the method can simultaneously represent mass transfer, spatially varying properties and network reactions without numerical problems, we have simulated the degradation of tetrachloroethylene (PCE) in a three-dimensional fully heterogeneous aquifer subjected to rate-limited mass transfer. Two types of degradation modes were considered to compare the effect of an active biofilm with that of clay pods present in the aquifer. Results of the two scenarios display significantly differences. Biofilms that promote the degradation of compounds in an immobile region are shown to significantly enhance degradation, rapidly producing

  2. A novel dopamine transporter transgenic mouse line for identification and purification of midbrain dopaminergic neurons reveals midbrain heterogeneity

    DEFF Research Database (Denmark)

    Christiansen, Mia Apuschkin; Stilling, Sara; Rahbek-Clemmensen, Troels


    Midbrain dopaminergic (DAergic) neurons are a heterogeneous cell group, composed of functionally distinct cell populations projecting to the basal ganglia, prefrontal cortex and limbic system. Despite their functional significance, the midbrain population of DAergic neurons is sparse, constituting...... only 20 000-30 000 neurons in mice, and development of novel tools to identify these cells is warranted. Here, a bacterial artificial chromosome mouse line [Dat1-enhanced green fluorescent protein (eGFP)] from the Gene Expression Nervous System Atlas (GENSAT) that expresses eGFP under control...

  3. Upscaling of U(VI) Desorption and Transport from Decimeter-Scale Heterogeneity to Plume-Scale Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Curtis, Gary P. [U.S. Geological Survey, Menlo Park, CA (United States); Kohler, Matthias [U.S. Geological Survey, Menlo Park, CA (United States); Kannappan, Ramakrishnan [U.S. Geological Survey, Menlo Park, CA (United States); Briggs, Martin [U.S. Geological Survey, Menlo Park, CA (United States); Day-Lewis, Fred [U.S. Geological Survey, Menlo Park, CA (United States)


    Scientifically defensible predictions of field scale U(VI) transport in groundwater requires an understanding of key processes at multiple scales. These scales range from smaller than the sediment grain scale (less than 10 μm) to as large as the field scale which can extend over several kilometers. The key processes that need to be considered include both geochemical reactions in solution and at sediment surfaces as well as physical transport processes including advection, dispersion, and pore-scale diffusion. The research summarized in this report includes both experimental and modeling results in batch, column and tracer tests. The objectives of this research were to: (1) quantify the rates of U(VI) desorption from sediments acquired from a uranium contaminated aquifer in batch experiments;(2) quantify rates of U(VI) desorption in column experiments with variable chemical conditions, and(3) quantify nonreactive tracer and U(VI) transport in field tests.

  4. Porosity Development in a Coastal Setting: A Reactive Transport Model to Assess the Influence of Heterogeneity of Hydrological, Geochemical and Lithological Conditions (United States)

    Maqueda, A.; Renard, P.; Cornaton, F. J.


    Coastal karst networks are formed by mineral dissolution, mainly calcite, in the freshwater-saltwater mixing zone. The problem has been approached first by studying the kinetics of calcite dissolution and then coupling ion-pairing software with flow and mass transport models. Porosity development models require high computational power. A workaround to reduce computational complexity is to assume the calcite dissolution reaction is relatively fast, thus equilibrium chemistry can be used to model it (Sanford & Konikow, 1989). Later developments allowed the full coupling of kinetics and transport in a model. However kinetics effects of calcite dissolution were found negligible under the single set of assumed hydrological and geochemical boundary conditions. A model is implemented with the coupling of FeFlow software as the flow & transport module and PHREEQC4FEFLOW (Wissmeier, 2013) ion-pairing module. The model is used to assess the influence of heterogeneities in hydrological, geochemical and lithological boundary conditions on porosity evolution. The hydrologic conditions present in the karst aquifer of Quintana Roo coast in Mexico are used as a guide for generating inputs for simulations.

  5. Ion exchange phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Bourg, I.C.; Sposito, G.


    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).

  6. Rheological phenomena in focus

    CERN Document Server

    Boger, DV


    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

  7. Heterogeneity of road traffic accident rate in the Russian cities and the need of usage various methods of transport safety management (United States)

    Petrov, A. I.; Petrova, D. A.


    The article considers one of the topical problems of road safety management at the federal level - the problem of the heterogeneity of road traffic accident rate in Russian cities. The article analyzes actual statistical data on road traffic accident rate in the administrative centers of Russia. The histograms of the distribution of the values of two most important road accidents characteristics - Social Risk HR and Severity Rate of Road Accidents - formed in 2016 in administrative centers of Russia are presented. On the basis of the regression model of the statistical connection between Severity Rate of Road Accidents and Social Risk HR, a classification of the Russian cities based on the level of actual road traffic accident rate was developed. On the basis of this classification a differentiated system of priority methods for organizing the safe functioning of transport systems in the cities of Russia is proposed.

  8. Evaluation of the Effect of Geological Heterogeneity on the Surfactant Transport by Performing Push-Pull Test in a Physical Aquifer Model (PAM) (United States)

    Kim, Y.; Lim, D.; Park, S.; Hong, U.; Lim, J.; Lee, W.; Kwon, S.


    A surfactant flushing process is commonly used to remove light non-aqueous phase liquids (LNAPLs) such as benzene, toluene, ethylbenzene, and xylene (BTEX) by enhancing solubility of the contaminants. Since the surfactant flushing process is significantly affected by the degree of geological heterogeneity, push-pull tests in a physical aquifer model (PAM) was performed to evaluate the surfactant transport and toluene removal efficiency in a lab-scale three layered aquifer. Push-pull tests showed that maximum bromide concentration detected at a sampling port located 15 cm downgradient from an injection port was approximately 95% of average injected bromide concentration in two permeable layers (0.22±0.02 cm/min of hydraulic conductivity) and only 40% in lower permeable layers (0.05±0.02 cm/min of hydraulic conductivity). Through the push-pull tests, we also found the different mass recovery of bromide (58%), toluene (47%) and surfactant (17%) in the PAM, confirming higher absorption characteristics of the surfactant on the soil particle than other solutes. Interestingly, toluene mass recovery in the presence of excessive surfactant decreased, possibly because of adsorption of toluene mass on the surfactant attached to soil particle. Through this work, we proved soil permeability, adsorption rate of surfactant, and amount of injected surfactant should be considered to remove the LNAPL contaminants efficiently by surfactant flushing process from the heterogeneous aquifer.

  9. Adaptive Mesh Refinement for a Finite Volume Method for Flow and Transport of Radionuclides in Heterogeneous Porous Media

    Directory of Open Access Journals (Sweden)

    Amaziane Brahim


    Full Text Available In this paper, we consider adaptive numerical simulation of miscible displacement problems in porous media, which are modeled by single phase flow equations. A vertex-centred finite volume method is employed to discretize the coupled system: the Darcy flow equation and the diffusion-convection concentration equation. The convection term is approximated with a Godunov scheme over the dual finite volume mesh, whereas the diffusion-dispersion term is discretized by piecewise linear conforming finite elements. We introduce two kinds of indicators, both of them of residual type. The first one is related to time discretization and is local with respect to the time discretization: thus, at each time, it provides an appropriate information for the choice of the next time step. The second is related to space discretization and is local with respect to both the time and space variable and the idea is that at each time it is an efficient tool for mesh adaptivity. An error estimation procedure evaluates where additional refinement is needed and grid generation procedures dynamically create or remove fine-grid patches as resolution requirements change. The method was implemented in the software MELODIE, developed by the French Institute for Radiological Protection and Nuclear Safety (IRSN, Institut de Radioprotection et de Sûreté Nucléaire. The algorithm is then used to simulate the evolution of radionuclide migration from the waste packages through a heterogeneous disposal, demonstrating its capability to capture complex behavior of the resulting flow.

  10. Bioelectrochemistry II membrane phenomena

    CERN Document Server

    Blank, M


    This book contains the lectures of the second course devoted to bioelectro­ chemistry, held within the framework of the International School of Biophysics. In this course another very large field of bioelectrochemistry, i. e. the field of Membrane Phenomena, was considered, which itself consists of several different, but yet related subfields. Here again, it can be easily stated that it is impossible to give a complete and detailed picture of all membrane phenomena of biological interest in a short course of about one and half week. Therefore the same philosophy, as the one of the first course, was followed, to select a series of lectures at postgraduate level, giving a synthesis of several membrane phenomena chosen among the most'important ones. These lectures should show the large variety of membrane-regulated events occurring in living bodies, and serve as sound interdisciplinary basis to start a special­ ized study of biological phenomena, for which the investigation using the dual approach, physico-che...

  11. Fundamentals of wave phenomena

    CERN Document Server

    Hirose, Akira


    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.

  12. Transport phenomena for chemical reactor design

    National Research Council Canada - National Science Library

    Belfiore, Laurence A


    ...-Averaged Specific Heats, 48 3-2 Conversion Dependence of Mass Fraction and Heat Capacity of the Mixture, 50 3-3 Plug-Flow Mass Balance in Terms of CO Conversion, 51 3-4 Thermal Energy Balance for ...

  13. [Study of multicomponent diffusion and transport phenomena

    Energy Technology Data Exchange (ETDEWEB)


    The major activities in this period are the percolation threshold in electronic conduction in [beta]-alumina type solid electrolytes, mixed alkali effects in ion conducting binary glasses, chemical diffusion problems, semiconductors, and relaxation process in diffusion. The last one constitutes the recent progress.

  14. Uranium Pyrophoricity Phenomena and Prediction

    Energy Technology Data Exchange (ETDEWEB)

    DUNCAN, D.R.


    We have compiled a topical reference on the phenomena, experiences, experiments, and prediction of uranium pyrophoricity for the Hanford Spent Nuclear Fuel Project (SNFP) with specific applications to SNFP process and situations. The purpose of the compilation is to create a reference to integrate and preserve this knowledge. Decades ago, uranium and zirconium fires were commonplace at Atomic Energy Commission facilities, and good documentation of experiences is surprisingly sparse. Today, these phenomena are important to site remediation and analysis of packaging, transportation, and processing of unirradiated metal scrap and spent nuclear fuel. Our document, bearing the same title as this paper, will soon be available in the Hanford document system [Plys, et al., 2000]. This paper explains general content of our topical reference and provides examples useful throughout the DOE complex. Moreover, the methods described here can be applied to analysis of potentially pyrophoric plutonium, metal, or metal hydride compounds provided that kinetic data are available. A key feature of this paper is a set of straightforward equations and values that are immediately applicable to safety analysis.

  15. Functional theories of thermoelectric phenomena (United States)

    Eich, F. G.; Di Ventra, M.; Vignale, G.


    We review the progress that has been recently made in the application of time-dependent density functional theory to thermoelectric phenomena. As the field is very young, we emphasize open problems and fundamental issues. We begin by introducing the formal structure of thermal density functional theory, a density functional theory with two basic variables—the density and the energy density—and two conjugate fields—the ordinary scalar potential and Luttinger’s thermomechanical potential. The static version of this theory is contrasted with the familiar finite-temperature density functional theory, in which only the density is a variable. We then proceed to constructing the full time-dependent non equilibrium theory, including the practically important Kohn-Sham equations that go with it. The theory is shown to recover standard results of the Landauer theory for thermal transport in the steady state, while showing greater flexibility by allowing a description of fast thermal response, temperature oscillations and related phenomena. Several results are presented here for the first time, i.e. the proof of invertibility of the thermal response function in the linear regime, the full expression of the thermal currents in the presence of Luttinger’s thermomechanical potential, an explicit prescription for the evaluation of the Kohn-Sham potentials in the adiabatic local density approximation, a detailed discussion of the leading dissipative corrections to the adiabatic local density approximation and the thermal corrections to the resistivity that follow from it.

  16. When good statistical models of aquifer heterogeneity go right: The impact of aquifer permeability structures on 3D flow and transport (United States)

    Jankovic, I.; Maghrebi, M.; Fiori, A.; Dagan, G.


    Natural gradient steady flow of mean velocity U takes place in heterogeneous aquifers of random logconductivity Y = lnK , characterized by the univariate PDF f(Y) and autocorrelation ρY. Solute transport is analyzed through the Breakthrough Curve (BTC) at planes at distance x from the injection plane. The study examines the impact of permeability structures sharing same f(Y) and ρY, but differing in higher order statistics (integral scales of variograms of Y classes) upon the numerical solution of flow and transport. Flow and transport are solved for 3D structures, rather than the 2D models adopted in most of previous works. We considered a few permeability structures, including the widely employed multi-Gaussian, the connected and disconnected fields introduced by Zinn and Harvey [2003] and a model characterized by equipartition of the correlation scale among Y values. We also consider the impact of statistical anisotropy of Y, the shape of ρY and local diffusion. The main finding is that unlike 2D, the prediction of the BTC of ergodic plumes by numerical and analytical models for different structures is quite robust, displaying a seemingly universal behavior, and can be used with confidence in applications. However, as a prerequisite the basic parameters KG (the geometric mean), σY2 (the logconductivity variance) and I (the horizontal integral scale of ρY) have to be identified from field data. The results suggest that narrowing down the gap between the BTCs in applications can be achieved by obtaining Kef (the effective conductivity) or U independently (e.g. by pumping tests), rather than attempting to characterize the permeability structure beyond f(Y) and ρY.

  17. Foot Morphometric Phenomena


    Agić, Ante


    Knowledge of the foot morphometry is important for proper foot structure and function. Foot structure as a vital part of human body is important for many reasons. The foot anthropometric and morphology phenomena are analyzed together with hidden biomechanical descriptors in order to fully characterize foot functionality. For Croatian student population the scatter data of the individual foot variables were interpolated by multivariate statistics. Foot morphometric descriptors are ...

  18. Paramutation phenomena in plants. (United States)

    Pilu, Roberto


    Paramutation is a particular epigenetic phenomenon discovered in Zea mays by Alexander Brink in the 1950s, and then also found in other plants and animals. Brink coined the term paramutation (from the Greek syllable "para" meaning beside, near, beyond, aside) in 1958, with the aim to differentiate paramutation from mutation. The peculiarity of paramutation with respect to other gene silencing phenomena consists in the ability of the silenced allele (named paramutagenic) to silence the other allele (paramutable) present in trans. The newly silenced (paramutated) allele remains stable in the next generations even after segregation from the paramutagenic allele and acquires paramutagenic ability itself. The inheritance behaviour of these epialleles permits a fast diffusion of a particular gene expression level/phenotype in a population even in the absence of other evolutionary influences, thus breaking the Hardy-Weinberg law. As with other gene silencing phenomena such as quelling in the fungus Neurospora crassa, transvection in Drosophila, co-suppression and virus-induced gene silencing (VIGS) described in transgenic plants and RNA interference (RNAi) in the nematode Caenorhabditis elegans, paramutation occurs without changes in the DNA sequence. So far the molecular basis of paramutation remains not fully understood, although many studies point to the involvement of RNA causing changes in DNA methylation and chromatin structure of the silenced genes. In this review I summarize all paramutation phenomena described in plants, focusing on the similarities and differences between them. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Monitoring mass transport in heterogeneously catalyzed reactions by field-gradient NMR for assessing reaction efficiency in a single pellet. (United States)

    Buljubasich, L; Blümich, B; Stapf, S


    An important aspect in assessing the performance of a catalytically active reactor is the accessibility of the reactive sites inside the individual pellets, and the mass transfer of reactants and products to and from these sites. Optimal design often requires a suitable combination of micro- and macropores in order to facilitate mass transport inside the pellet. In an exothermic reaction, fluid exchange between the pellet and the surrounding medium is enhanced by convection, and often by the occurrence of gas bubbles. Determining mass flow in the vicinity of a pellet thus represents a parameter for quantifying the reaction efficiency and its dependence on time or external reaction conditions. Field gradient Nuclear Magnetic Resonance (NMR) methods are suggested as a tool for providing parameters sensitive to this mass flow in a contact-free and non-invasive way. For the example of bubble-forming hydrogen peroxide decomposition in an alumina pellet, the dependence of the mean-squared displacement of fluid molecules on spatial direction, observation time and reaction time is presented, and multi-pulse techniques are employed in order to separate molecular displacements from coherent and incoherent motion on the timescale of the experiment. The reaction progress is followed until the complete decomposition of H2O2. Copyright © 2011 Elsevier Inc. All rights reserved.

  20. Exploring the worth of geophysical data for characterizing three dimensional transport and heterogeneity in laboratory aquifer experiment (United States)

    Urban, R. L.; Reed, P. M.; Singha, K.


    This study evaluates how geophysical data and tracer concentration time series data can be combined effectively to infer hydraulic properties of a laboratory aquifer tank experiment. The tank's dimensions are 73 cm x 71 cm x 70 cm with a 20 cm fine sand cube placed in the center of the tank, within a larger cube of coarser sand. A series of three experiments are conducted within the tank: (1) lateral extent experiments, (2) concentration experiments, and (3) sampling configuration experiments. The set of lateral extent experiments examine how sensitive geophysical data is to the lateral extent of the tracer injection. The concentration experiments examine how sensitive geophysical data is to the level of concentration injected into the tank. Finally, the sample configuration experiments examine how the length of the geophysical sequence affects the balance between data resolution and temporal smearing of geophysical data. The geophysical data is analyzed using both moment analysis of tomograms and the time series data is analyzed using root mean square error (RMSE) and transformed root mean square error (TRMSE) metrics. The metrics are then compared with modeled data to determine the bias between prediction and observation data. In the end, our results show that geophysical data can be used effectively to incorporate hydrological properties, with a few caveats. The primary contribution of this work is to clarify the effect that experimental design decisions for geophysics (location of electrodes, sequence of electrodes, etc.) have on our ability to describe aquifer properties and evaluate tracer transport.

  1. Benchmarking numerical codes for tracer transport with the aid of laboratory-scale experiments in 2D heterogeneous porous media. (United States)

    Maina, Fadji Hassane; Ackerer, Philippe; Younes, Anis; Guadagnini, Alberto; Berkowitz, Brian


    We present a combined experimental and numerical modeling study that addresses two principal questions: (i) is any particular Eulerian-based method used to solve the classical advection-dispersion equation (ADE) clearly superior (relative to the others), in terms of yielding solutions that reproduce BTCs of the kind that are typically sampled at the outlet of a laboratory cell? and (ii) in the presence of matches of comparable quality against such BTCs, do any of these methods render different (or similar) numerical BTCs at locations within the domain? To address these questions, we obtained measurements from carefully controlled laboratory experiments, and employ them as a reference against which numerical results are benchmarked and compared. The experiments measure solute transport breakthrough curves (BTCs) through a square domain containing various configurations of coarse, medium, and fine quartz sand. The approaches to solve the ADE involve Eulerian-Lagrangian and Eulerian (finite volume, finite elements, mixed and discontinuous finite elements) numerical methods. Model calibration is not examined; permeability and porosity of each sand were determined previously through separate, standard laboratory tests, while dispersivities are assigned values proportional to mean grain size. We find that the spatial discretization of the flow field is of critical importance, due to the non-uniformity of the domain. Although simulated BTCs at the system outlet are observed to be very similar for these various numerical methods, computed local (point-wise, inside the domain) BTCs can be very different. We find that none of the numerical methods is able to fully reproduce the measured BTCs. The impact of model parameter uncertainty on the calculated BTCs is characterized through a set of numerical Monte Carlo simulations; in cases where the impact is significant, assessment of simulation matches to the experimental data can be ambiguous. Copyright © 2017 Elsevier B.V. All

  2. Correspondence Between One- and Two-Equation Models for Solute Transport in Two-Region Heterogeneous Porous Media

    KAUST Repository

    Davit, Y.


    In this work, we study the transient behavior of homogenized models for solute transport in two-region porous media. We focus on the following three models: (1) a time non-local, two-equation model (2eq-nlt). This model does not rely on time constraints and, therefore, is particularly useful in the short-time regime, when the timescale of interest (t) is smaller than the characteristic time (τ 1) for the relaxation of the effective macroscale parameters (i. e., when t ≤ τ 1); (2) a time local, two-equation model (2eq). This model can be adopted when (t) is significantly larger than (τ 1) (i.e., when t≫τ 1); and (3) a one-equation, time-asymptotic formulation (1eq ∞). This model can be adopted when (t) is significantly larger than the timescale (τ 2) associated with exchange processes between the two regions (i. e., when t≫τ 2). In order to obtain insight into this transient behavior, we combine a theoretical approach based on the analysis of spatial moments with numerical and analytical results in several simple cases. The main result of this paper is to show that there is only a weak asymptotic convergence of the solution of (2eq) towards the solution of (1eq ∞) in terms of standardized moments but, interestingly, not in terms of centered moments. The physical interpretation of this result is that deviations from the Fickian situation persist in the limit of long times but that the spreading of the solute is eventually dominating these higher order effects. © 2012 Springer Science+Business Media B.V.

  3. SU-E-T-519: Experimental Evaluation of Deterministic Acuros XB Radiation Transport Algorithm for Heterogeneity Dose Calculation Using the Radiological Physics Center's Lung Phantom. (United States)

    Han, T; Mourtada, F; Repchak, R; Tonigan, J; Mikell, J; Howell, R; Salehpour, M; Molineu, A; Followill, D


    To evaluate the heterogeneity corrected dose calculations from the Acuros XB (AXB), a novel deterministic dose calculation algorithm based on grid-based Boltzmann transport equation solver (GBBS), for IMRT and VMAT plans. The Radiological Physics Center's lung phantom was used to create clinically equivalent IMRT and VMAT plans (RapidArc) with the Eclipse planning system 10.0 that were delivered using a Varian 23 iX. Absolute doses and relative dose distributions were measured with thermoluminescent dosimeters (TLDs) and radiochromic film. The measured dose distributions were compared with calculated doses from both AXB (11.0.3) and AAA (10.0.24) dose calculation algorithms. The AXB calculated dose-to-water and dose-to-medium were both compared to measurements. Gamma analysis (±7%/4mm, ±5%/3mm, and ±3%/3mm) was used to quantify correspondence between AXB dose distributions and the film measurements. The computation time between AAA and AXB were also evaluated. For TLD point doses, both AAA and AXB heterogeneity corrected dose calculations are within 5% inside the PTV for both IMRT and VMAT plans. The agreements observed between the measured and calculated doses for both AXB dose reporting methods are better than those observed with the AAA algorithm. The gamma analysis showed that the differences between AAA, AXB and film measurement met the RPC ±7%/4 mm criteria. The percent of pixels passing rate for both the AXB dose to medium and AXB dose to water are higher than AAA. The computation time between AAA and AXB are comparable for IMRT plans but AXB is significantly faster (4 times) than AAA for VMAT plans. The AXB implemented in the Eclipse planning system calculates a more accurate heterogeneity corrected dose than the AAA algorithm as compared to measurement in lung and improve the calculation speed for VMAT radiotherapy. Work supported by grants CA10953, CA81647, 2R44CA105806-02, CA016672 (NCI, DHHS). © 2012 American Association of Physicists in Medicine.

  4. On Process Modelling Using Physical Oriented And Phenomena Based Principles

    Directory of Open Access Journals (Sweden)

    Mihai Culea


    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.

  5. Solid state phenomena

    CERN Document Server

    Lawrance, R


    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

  6. Interfacial phenomena and the ocular surface. (United States)

    Yañez-Soto, Bernardo; Mannis, Mark J; Schwab, Ivan R; Li, Jennifer Y; Leonard, Brian C; Abbott, Nicholas L; Murphy, Christopher J


    Ocular surface disorders, such as dry eye disease, ocular rosacea, and allergic conjunctivitis, are a heterogeneous group of diseases that require an interdisciplinary approach to establish underlying causes and develop effective therapeutic strategies. These diverse disorders share a common thread in that they involve direct changes in ocular surface chemistry as well as the rheological properties of the tear film and topographical attributes of the cellular elements of the ocular surface. Knowledge of these properties is crucial to understand the formation and stability of the preocular tear film. The study of interfacial phenomena of the ocular surface flourished during the 1970s and 1980s, but after a series of lively debates in the literature concerning distinctions between the epithelial and the glandular origin of ocular surface disorders during the 1990s, research into this important topic has declined. In the meantime, new tools and techniques for the characterization and functionalization of biological surfaces have been developed. This review summarizes the available literature regarding the physicochemical attributes of the ocular surface, analyzes the role of interfacial phenomena in the pathobiology of ocular surface disease, identifies critical knowledge gaps concerning interfacial phenomena of the ocular surface, and discusses the opportunities for the exploitation of these phenomena to develop improved therapeutics for the treatment of ocular surface disorders. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Materials and Breakdown Phenomena: Heterogeneous Molybdenum Metallic Films

    Directory of Open Access Journals (Sweden)

    Augusto Marcelli


    Full Text Available Technological activities to design, manufacture, and test new accelerating devices using different materials and methods is under way all over the world. The main goal of these studies is to increase the accelerating gradients and reduce the probability of radio-frequency (RF breakdown. Indeed, it is still not clear why, by increasing the intensity of the applied field, intense surface damage is observed in copper structures, limiting the lifetime and, therefore, the practical applications. A possible solution is represented by a coating of a relatively thick layer of molybdenum in order to improve the breakdown rate. molybdenum can be reliably grown on different substrates with a negligible strain and, for thicknesses up to 600 nm, with a resistivity < 100–150·μΩ cm. Moreover, Mo coatings with controlled composition, internal stress, and roughness may allow improving thermo-mechanical properties reaching values not attainable by uncoated copper. Although the Mo conductivity remains lower compared to Cu, a Mo coating represents a very interesting option for high gradient accelerator components manufactured in copper.


    Energy Technology Data Exchange (ETDEWEB)



    This project developed and supported a technology base in nonequilibrium phenomena underpinning fundamental issues in condensed matter and materials science, and applied this technology to selected problems. In this way the increasingly sophisticated synthesis and characterization available for classes of complex electronic and structural materials provided a testbed for nonlinear science, while nonlinear and nonequilibrium techniques helped advance our understanding of the scientific principles underlying the control of material microstructure, their evolution, fundamental to macroscopic functionalities. The project focused on overlapping areas of emerging thrusts and programs in the Los Alamos materials community for which nonlinear and nonequilibrium approaches will have decisive roles and where productive teamwork among elements of modeling, simulations, synthesis, characterization and applications could be anticipated--particularly multiscale and nonequilibrium phenomena, and complex matter in and between fields of soft, hard and biomimetic materials. Principal topics were: (i) Complex organic and inorganic electronic materials, including hard, soft and biomimetic materials, self-assembly processes and photophysics; (ii) Microstructure and evolution in multiscale and hierarchical materials, including dynamic fracture and friction, dislocation and large-scale deformation, metastability, and inhomogeneity; and (iii) Equilibrium and nonequilibrium phases and phase transformations, emphasizing competing interactions, frustration, landscapes, glassy and stochastic dynamics, and energy focusing.

  9. Workshop on Interface Phenomena

    CERN Document Server

    Kreuzer, Hans


    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...

  10. Transportation (United States)


    container. It now permits free transit of shipping containers from their western ports, if transported by rail directly to the U.S. ( Mireles , 2005, p...Transportation Industry Study Seminar. Mireles , Richard, Castillo. (2005, January). A Cure for West Coast Congestion. Logistics Today, Vol. 46, Issue 1. 1

  11. Field heterogeneity: some basic issues

    Energy Technology Data Exchange (ETDEWEB)

    Philip, J.R.


    Present-day soil-water physics enables useful quantitative predictions in the laboratory and in simple field situations. However, difficulties frequently arise for areas of appreciable size in the field. Two types of heterogeneity are distinguished: deterministic and stochastic. The first often demands an extension of established analyses and may involve important phenomena absent from the analogous homogeneous problem. Stochastic heterogeneity may involve many scales and is imperfectly known. The statistical properties may be stationary, but in more complicated cases, randomness may be embedded in (either known or unknown) systematic trends. Some aspects of unsaturated and generally unsteady flow in heterogeneous systems are reviewed: the mathematical nature of the flow equation; the concept of scale-heterogeneity; analytical and quasianalytical solutions. The enormity of the total problem of unsaturated unsteady flow in stochastic heterogeneous systems is illustrated through a dialectic of 8 successive stages of simplification. 37 references.

  12. Emergent Phenomena at Oxide Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, H.Y.


    Transition metal oxides (TMOs) are an ideal arena for the study of electronic correlations because the s-electrons of the transition metal ions are removed and transferred to oxygen ions, and hence the strongly correlated d-electrons determine their physical properties such as electrical transport, magnetism, optical response, thermal conductivity, and superconductivity. These electron correlations prohibit the double occupancy of metal sites and induce a local entanglement of charge, spin, and orbital degrees of freedom. This gives rise to a variety of phenomena, e.g., Mott insulators, various charge/spin/orbital orderings, metal-insulator transitions, multiferroics, and superconductivity. In recent years, there has been a burst of activity to manipulate these phenomena, as well as create new ones, using oxide heterostructures. Most fundamental to understanding the physical properties of TMOs is the concept of symmetry of the order parameter. As Landau recognized, the essence of phase transitions is the change of the symmetry. For example, ferromagnetic ordering breaks the rotational symmetry in spin space, i.e., the ordered phase has lower symmetry than the Hamiltonian of the system. There are three most important symmetries to be considered here. (i) Spatial inversion (I), defined as r {yields} -r. In the case of an insulator, breaking this symmetry can lead to spontaneous electric polarization, i.e. ferroelectricity, or pyroelectricity once the point group belongs to polar group symmetry. (ii) Time-reversal symmetry (T) defined as t {yields} -t. In quantum mechanics, the time-evolution of the wave-function {Psi} is given by the phase factor e{sup -iEt/{h_bar}} with E being the energy, and hence time-reversal basically corresponds to taking the complex conjugate of the wave-function. Also the spin, which is induced by the 'spinning' of the particle, is reversed by time-reversal. Broken T-symmetry is most naturally associated with magnetism, since the

  13. Modelling of CVD reactors : thermochemical and mass transport approaches for Si1-xGex deposition


    Rouch, H.; Pons, M.; Benezech, A.; Barbier, J.; Bernard, C.; Madar, R.


    Over the years, the design of chemical vapor deposition processes has relied on accumulated empirical ability. It is now well established that the properties of films grown by this chemical process are strongly determined by both transport phenomena and homogeneous and heterogeneous reactions in the reactor. Thermodynamic calculations and mass transport modeling provide a possible approach to delineate the general features of a given process. The application of this concept to the deposition ...

  14. Modelization of physical phenomena in research reactors with the help of new developments in transport methods, and methodology validation with experimental data; Modelisation des phenomenes physiques dans les reacteurs de recherche a l'aide de developpements realises dans les methodes de transport et qualification

    Energy Technology Data Exchange (ETDEWEB)

    Rauck, St


    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)

  15. Mesoscopic phenomena in solids

    CERN Document Server

    Altshuler, BL; Webb, RA


    The physics of disordered systems has enjoyed a resurgence of interest in the last decade. New concepts such as weak localization, interaction effects and Coulomb gap, have been developed for the transport properties of metals and insulators. With the fabrication of smaller and smaller samples and the routine availability of low temperatures, new physics has emerged from the studies of small devices. The new field goes under the name ""mesoscopic physics"" and has rapidly developed, both experimentally and theoretically. This book is designed to review the current status of the field.

  16. A Photochemical Reactor for the Study of Kinetics and Adsorption Phenomena (United States)

    Poce-Fatou, J. A.; Gil, M. L. A.; Alcantara, R.; Botella, C.; Martin, J.


    The interaction between light and matter is examined with the help of a photochemical experiment. This experiment is useful for the investigation of heterogeneous catalysis, semiconductor properties and adsorption phenomena.

  17. Transportes

    Directory of Open Access Journals (Sweden)

    Hidalgo Fernández-Cano, Amalio


    Full Text Available El movimiento de materiales dentro de la Factoría está atendido por tres principales medios de transporte, en consonancia con las características del material y de los desplazamientos. Así se han establecido: sistemas de cintas transportadoras, una red ferroviaria de ancho normal y una completa malla de caminos enlazando funcionalmente las instalaciones.

  18. Heterogeneous Catalysis. (United States)

    Miranda, R.


    Described is a heterogeneous catalysis course which has elements of materials processing embedded in the classical format of catalytic mechanisms and surface chemistry. A course outline and list of examples of recent review papers written by students are provided. (MVL)

  19. Studies on the heterogeneous electron transport and oxygen reduction reaction at metal (Co, Fe) octabutylsulphonylphthalocyanines supported on multi-walled carbon nanotube modified graphite electrode

    CSIR Research Space (South Africa)

    Mamuru, SA


    Full Text Available Heterogeneous electron transfer dynamics and oxygen reduction reaction (ORR) activities using octabutylsulphonylphthalocyanine complexes of iron (FeOBSPc) and cobalt (CoOBSPc) supported on multi-walled carbon nanotube (MWCNT) platforms have been...

  20. Neutronics calculation of an heterogeneous compact and thermal core by means of deterministic and stochastic transport theory. Application to the experimental reactor of the University of Strasbourg; Modelisation neutronique d`un coeur thermique compact et heterogene en theorie du transport deterministe et probabiliste. Application au reacteur experimental de l`Universite de Strasbourg

    Energy Technology Data Exchange (ETDEWEB)

    Jammes, Ch


    The aim of this work is to create, validate theoretically and experimentally a calculation route for a thermal irradiation reactor. This is the research reactor of the University of Strasbourg, which presents all of characteristics of this reactor-type: compact and heterogeneous core, slab-type fuel with a high 235-uranium enrichment. This calculation route is based on the first use of the following two modern transport methods: the TDT method and the Monte Carlo method. The former, programmed within the APOLLO2 code, is a two dimensional collision probabilities method. The later, used by the TRIPOLI4 code, is a stochastic method. Both can be applied to complex geometries. After a few theoretical reminders about transport codes, a set of integral experiments is described which have been realized within the research reactor of the University of Strasbourg. One of them has been performed for this study. At the beginning of the theoretical part, significant errors are apparent due to the use of calculation route based on homogenization, condensation and the diffusion approximation. An extensive comparison between the discrete ordinates method and the TDT method carries out that the use of the TDT method is relevant for the studied reactor. The treatment of axial leakage with this method is the only disadvantage. Therefore, the use of the code TRIPOLI4 is recommended for a more accurate study of leakage within a reflector. By means of the experimental data, the ability of our calculation route is confirmed for essential neutronics questions such as the critical mass determination, the power distribution and the fuel management. (author)

  1. Effects of incomplete mixing on chemical reactions under flow heterogeneities. (United States)

    Perez, Lazaro; Hidalgo, Juan J.; Dentz, Marco


    Evaluation of the mixing process in aquifers is of primary importance when assessing attenuation of pollutants. In aquifers different hydraulic and chemical properties can increase mixing and spreading of the transported species. Mixing processes control biogeochemical transformations such as precipitation/dissolution reactions or degradation reactions that are fast compared to mass transfer processes. Reactions are local phenomena that fluctuate at the pore scale, but predictions are often made at much larger scales. However, aquifer heterogeities are found at all scales and generates flow heterogeneities which creates complex concentration distributions that enhances mixing. In order to assess the impact of spatial flow heterogeneities at pore scale we study concentration profiles, gradients and reaction rates using a random walk particle tracking (RWPT) method and kernel density estimators to reconstruct concentrations and gradients in two setups. First, we focus on a irreversible bimolecular reaction A+B → C under homogeneous flow to distinguish phenomena of incomplete mixing of reactants from finite-size sampling effects. Second, we analise a fast reversible bimolecular chemical reaction A+B rightleftharpoons C in a laminar Poiseuille flow reactor to determine the difference between local and global reaction rates caused by the incomplete mixing under flow heterogeneities. Simulation results for the first setup differ from the analytical solution of the continuum scale advection-dispersion-reaction equation studied by Gramling et al. (2002), which results in an overstimation quantity of reaction product (C). In the second setup, results show that actual reaction rates are bigger than the obtained from artificially mixing the system by averaging the concentration vertically. - LITERATURE Gramling, C. M.,Harvey, C. F., Meigs, and L. C., (2002). Reactive transport in porous media: A comparison of model prediction with laboratory visualization, Environ. Sci

  2. Nanoscale and microscale phenomena fundamentals and applications

    CERN Document Server

    Khandekar, Sameer


    The book is an outcome of research work in the areas of nanotechnology, interfacial science, nano- and micro-fluidics and manufacturing, soft matter, and transport phenomena at nano- and micro-scales. The contributing authors represent prominent research groups from Indian Institute of Technology Bombay, Indian Institute of Technology Kanpur and Indian Institute of Science, Bangalore. The book has 13 chapters and the entire work presented in the chapters is based on research carried out over past three years. The chapters are designed with number of coloured illustrations, figures and tables. The book will be highly beneficial to academicians as well as industrial professionals working in the mentioned areas.

  3. Social phenomena from data analysis to models

    CERN Document Server

    Perra, Nicola


    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...

  4. Resolving Heterogeneity

    DEFF Research Database (Denmark)

    Hölzenspies, Jurriaan; Dela Cruz, Gelo Victoriano; M Brickman, Joshua


    sets of pluripotency and differentiation markers. It has become increasingly apparent that this transcriptional heterogeneity is an important characteristic of ESC culture. By sorting for specific populations of ESCs it is possible to enrich for cells with a capacity to colonize the embryo proper...

  5. Localization Phenomena in Disordered Tantalum Films

    Directory of Open Access Journals (Sweden)

    Natalia Kovaleva


    Full Text Available Using dc transport and wide-band spectroscopic ellipsometry techniques we study localization phenomena in highly disordered metallic β -Ta films grown by rf sputtering deposition. The dc transport study implies non-metallic behavior (d ρ /dT < 0, with negative temperature coefficient of resistivity (TCR. We found that as the absolute TCR value increased, specifying an elevated degree of disorder, the free charge carrier Drude response decreases, indicating the enhanced charge carrier localization. Moreover, we found that the pronounced changes occur at the extended spectral range, involving not only the Drude resonance, but also the higher-energy Lorentz bands, in evidence of the attendant electronic correlations. We propose that the charge carrier localization, or delocalization, is accompanied by the pronounced electronic band structure reconstruction due to many-body effects, which may be the key feature for understanding the physics of highly disordered metals.

  6. Exploiting transient phenomena for imaging with breath figures (United States)

    Sasikumar, Harish; Varma, Manoj M.


    Breath figures refer to the patterns formed when vapor condenses into the liquid phase on a surface, revealing heterogeneities in topography or chemical composition. These figures are composed of micro-droplets, which scatter light and produce optical contrast. Differences in hydrophobicity imposed by surface features or contaminants result in a difference in micro-droplet densities, which has been used in applications such as substrate independent optical visualization of single layer graphene flakes. Here, we show that transient phenomena, such as the pinning transition of micro-droplets condensed over a polymer surface, can be used to enhance the optical contrast even when the time averaged difference in micro-droplet densities is not substantial. Thus, this work opens a new way of visualizing surface heterogeneities using transient phenomena occurring during condensation or evaporation of micro-droplets as opposed to only using time averaged differences in wettability due to the surface features.

  7. Multi-level adaptive simulation of transient two-phase flow in heterogeneous porous media

    KAUST Repository

    Chueh, C.C.


    An implicit pressure and explicit saturation (IMPES) finite element method (FEM) incorporating a multi-level shock-type adaptive refinement technique is presented and applied to investigate transient two-phase flow in porous media. Local adaptive mesh refinement is implemented seamlessly with state-of-the-art artificial diffusion stabilization allowing simulations that achieve both high resolution and high accuracy. Two benchmark problems, modelling a single crack and a random porous medium, are used to demonstrate the robustness of the method and illustrate the capabilities of the adaptive refinement technique in resolving the saturation field and the complex interaction (transport phenomena) between two fluids in heterogeneous media. © 2010 Elsevier Ltd.

  8. Heterogeneous Gossip (United States)

    Frey, Davide; Guerraoui, Rachid; Kermarrec, Anne-Marie; Koldehofe, Boris; Mogensen, Martin; Monod, Maxime; Quéma, Vivien

    Gossip-based information dissemination protocols are considered easy to deploy, scalable and resilient to network dynamics. Load-balancing is inherent in these protocols as the dissemination work is evenly spread among all nodes. Yet, large-scale distributed systems are usually heterogeneous with respect to network capabilities such as bandwidth. In practice, a blind load-balancing strategy might significantly hamper the performance of the gossip dissemination.

  9. Critical Phenomena in Gravitational Collapse

    Directory of Open Access Journals (Sweden)

    Gundlach Carsten


    Full Text Available As first discovered by Choptuik, the black hole threshold in the space of initial data for general relativity shows both surprising structure and surprising simplicity. Universality, power-law scaling of the black hole mass, and scale echoing have given rise to the term 'critical phenomena'. They are explained by the existence of exact solutions which are attractors within the black hole threshold, that is, attractors of codimension one in phase space, and which are typically self-similar. This review gives an introduction to the phenomena, tries to summarize the essential features of what is happening, and then presents extensions and applications of this basic scenario. Critical phenomena are of interest particularly for creating surprising structure from simple equations, and for the light they throw on cosmic censorship and the generic dynamics of general relativity.

  10. Undergraduates' understanding of cardiovascular phenomena. (United States)

    Michael, Joel A; Wenderoth, Mary Pat; Modell, Harold I; Cliff, William; Horwitz, Barbara; McHale, Philip; Richardson, Daniel; Silverthorn, Dee; Williams, Stephen; Whitescarver, Shirley


    Undergraduates students in 12 courses at 8 different institutions were surveyed to determine the prevalence of 13 different misconceptions (conceptual difficulties) about cardiovascular function. The prevalence of these misconceptions ranged from 20 to 81% and, for each misconception, was consistent across the different student populations. We also obtained explanations for the students' answers either as free responses or with follow-up multiple-choice questions. These results suggest that students have a number of underlying conceptual difficulties about cardiovascular phenomena. One possible source of some misconceptions is the students' inability to apply simple general models to specific cardiovascular phenomena. Some implications of these results for teachers of physiology are discussed.

  11. Whistlers and related ionospheric phenomena

    CERN Document Server

    Helliwell, Robert A


    The investigation of whistlers and related phenomena is a key element in studies of very-low-frequency propagation, satellite communication, the outer ionosphere, and solar-terrestrial relationships. This comprehensive text presents a history of the study of the phenomena and includes all the elements necessary for the calculation of the characteristics of whistlers and whistler-mode signals.An introduction and brief history are followed by a summary of the theory of whistlers and a detailed explanation of the calculation of their characteristics. Succeeding chapters offer a complete atlas of

  12. Diffusion phenomena of cells and biomolecules in microfluidic devices. (United States)

    Yildiz-Ozturk, Ece; Yesil-Celiktas, Ozlem


    Biomicrofluidics is an emerging field at the cross roads of microfluidics and life sciences which requires intensive research efforts in terms of introducing appropriate designs, production techniques, and analysis. The ultimate goal is to deliver innovative and cost-effective microfluidic devices to biotech, biomedical, and pharmaceutical industries. Therefore, creating an in-depth understanding of the transport phenomena of cells and biomolecules becomes vital and concurrently poses significant challenges. The present article outlines the recent advancements in diffusion phenomena of cells and biomolecules by highlighting transport principles from an engineering perspective, cell responses in microfluidic devices with emphases on diffusion- and flow-based microfluidic gradient platforms, macroscopic and microscopic approaches for investigating the diffusion phenomena of biomolecules, microfluidic platforms for the delivery of these molecules, as well as the state of the art in biological applications of mammalian cell responses and diffusion of biomolecules.

  13. Overview. Department of Environmental and Radiation Transport Physics. Section 6

    Energy Technology Data Exchange (ETDEWEB)

    Loskiewicz, J. [Institute of Nuclear Physics, Cracow (Poland)


    Research activities in the Department of Environmental and Radiation Transport Physics are carried out by three Laboratories: Laboratory of Environmental Physics, Laboratory of Neutron Transport Physics and Laboratory of Physics and Modeling of Radiation Transport. The researches provided in 1994 cover: tracer transport and flows in porous media, studies on pollution in atmospheric air, physics of molecular phenomena in chromatographic detectors, studies on neutron transport in heterogenous media, studies on evaluation of neutron cross-section in the thermal region, studies on theory and utilization of neural network in data evaluation, numerical modelling of particle cascades for particle accelerator shielding purpose. In this section the description of mentioned activities as well as the information about personnel employed in the Department, papers and reports published in 1994, contribution to conferences and grants is also given.

  14. Nursing phenomena in inpatient psychiatry

    NARCIS (Netherlands)

    Frauenfelder, F.; Muller-Staub, M.; Needham, I.; Achterberg, T. van


    Little is known about the question if the nursing diagnosis classification of North American Nursing Association-International (NANDA-I) describes the adult inpatient psychiatric nursing care. The present study aimed to identify nursing phenomena mentioned in journal articles about the psychiatric

  15. A Course on Surface Phenomena. (United States)

    Woods, Donald R.


    Describes a graduate or senior elective course combining fundamentals of surface phenomena with practical problem-solving structured around a series of case problems. Discusses topics covered and their development through acquiring new knowledge applied to the case problem, practical calculations of solutions, and applications to additional…

  16. Discovery potential for new phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Godfrey, S. [Carleton Univ., Ottawa, Ontario (Canada). Ottawa Carleton Inst. for Physics; Hewett, J.L. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Price, L.E. [Argonne National Lab., IL (United States). High Energy Physics Div.


    The authors examine the ability of future facilities to discover and interpret non-supersymmetric new phenomena. The authors first explore explicit manifestations of new physics, including extended gauge sectors, leptoquarks, exotic fermions, and technicolor models. They then take a more general approach where new physics only reveals itself through the existence of effective interactions at lower energy scales.

  17. Collective Phenomena in Kidney Autoregulation

    DEFF Research Database (Denmark)

    Mosekilde, Erik; Sosnovtseva, Olga; Holstein-Rathlou, N.-H.


    , the nephron. However, a variety of cooperative phenomena arising through interactions between the nephrons may also be important. We prescut experimental evidence for a coupling between nephrons that are connected via a common piece of afferent arteriole. We also develop a mathematical model that call account...

  18. Documentation and verification of VST2D; a model for simulating transient, Variably Saturated, coupled water-heat-solute Transport in heterogeneous, anisotropic 2-Dimensional, ground-water systems with variable fluid density (United States)

    Friedel, Michael J.


    This report describes a model for simulating transient, Variably Saturated, coupled water-heatsolute Transport in heterogeneous, anisotropic, 2-Dimensional, ground-water systems with variable fluid density (VST2D). VST2D was developed to help understand the effects of natural and anthropogenic factors on quantity and quality of variably saturated ground-water systems. The model solves simultaneously for one or more dependent variables (pressure, temperature, and concentration) at nodes in a horizontal or vertical mesh using a quasi-linearized general minimum residual method. This approach enhances computational speed beyond the speed of a sequential approach. Heterogeneous and anisotropic conditions are implemented locally using individual element property descriptions. This implementation allows local principal directions to differ among elements and from the global solution domain coordinates. Boundary conditions can include time-varying pressure head (or moisture content), heat, and/or concentration; fluxes distributed along domain boundaries and/or at internal node points; and/or convective moisture, heat, and solute fluxes along the domain boundaries; and/or unit hydraulic gradient along domain boundaries. Other model features include temperature and concentration dependent density (liquid and vapor) and viscosity, sorption and/or decay of a solute, and capability to determine moisture content beyond residual to zero. These features are described in the documentation together with development of the governing equations, application of the finite-element formulation (using the Galerkin approach), solution procedure, mass and energy balance considerations, input requirements, and output options. The VST2D model was verified, and results included solutions for problems of water transport under isohaline and isothermal conditions, heat transport under isobaric and isohaline conditions, solute transport under isobaric and isothermal conditions, and coupled water

  19. Astronomical phenomena in Dresden codex

    Directory of Open Access Journals (Sweden)

    Böhm V.


    Full Text Available The relationship between Maya and our calendar is expressed by a coefficient known as ‘correlation’ which is a number of days that we have to add to the Mayan Long Count date to get Julian Date used in astronomy. There is surprisingly large uncertainty in the value of the correlation, yielding a shift between both calendars (and thus between the history of Maya and of our world to typically several hundred years. There are more than 50 diverse values of the correlation, some of them derived from historical, other by astronomical data. We test here (among others the well established Goodman-Martínez-Thompson correlation (GMT, based on historical data, and the Böhms’ one (B&B, based on astronomical data decoded from the Dresden Codex (DC; this correlation differs by about +104 years from the GMT. In our previous works we used several astronomical phenomena as recorded in the DC for a check. We clearly demonstrated that (i the GMT was not capable to predict these phenomena that really happened in nature and (ii that the GMT predicts them on the days when they did not occur. The phenomena used till now in the test are, however, short-periodic and the test then may suffer from ambiguity. Therefore, we add long-periodic astronomical phenomena, decoded successfully from the DC, to the testing. These are (i a synchrony of Venusian heliacal risings with the solar eclipses, (ii a synchrony of Venus and Mars conjunctions with the eclipses, (iii conjunctions of Jupiter and Saturn repeated in a rare way, and (iv a synchrony of synodic and sideric periods of Mercury with the tropical year. Based on our analysis, we find that the B&B correlation yields the best agreement with the astronomical phenomena observed by the Maya. Therefore we recommend to reject the GMT and support the B&B correlation.

  20. Multiscale Modeling of Mesoscale and Interfacial Phenomena (United States)

    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

  1. Interplay between the Charge Transport Phenomena and the Charge-Transfer Phase Transition in RbxMn[Fe(CN)(6)](y)center dot zH(2)O

    NARCIS (Netherlands)

    Molnar, Gabor; Cobo, Saioa; Mahfoud, Tarik; Vertelman, Esther J. M.; van Koningsbruggen, Petra J.; Demont, Philippe; Bousseksou, Azzedine


    Charge transport and dielectric measurements were carried out on compacted powder and single-crystal samples of bistable RbxMn[Fe(CN)(6)](y)center dot zH(2)O in the two valence-tautomeric forms ((MnFeIII)-Fe-II and (MnFeII)-Fe-III) as a function of temperature (120-350 K) and frequency (10(-2)-10(6)

  2. Peridynamic Formulation for Coupled Thermoelectric Phenomena

    Directory of Open Access Journals (Sweden)

    Migbar Assefa


    Full Text Available Modeling of heat and electrical current flow simultaneously in thermoelectric convertor using classical theories do not consider the influence of defects in the material. This is because traditional methods are developed based on partial differential equations (PDEs and lead to infinite fluxes at the discontinuities. The usual way of solving such PDEs is by using numerical technique, like Finite Element Method (FEM. Although FEM is robust and versatile, it is not suitable to model evolving discontinuities. To avoid such shortcomings, we propose the concept of peridynamic theory to derive the balance of energy and charge equations in the coupled thermoelectric phenomena. Therefore, this paper presents the transport of heat and charge in thermoelectric material in the framework of peridynamic (PD theory. To illustrate the reliability of the PD formulation, numerical examples are presented and results are compared with those from literature, analytical solutions, or finite element solutions.

  3. Thermodynamic constraints on fluctuation phenomena (United States)

    Maroney, O. J. E.


    The relationships among reversible Carnot cycles, the absence of perpetual motion machines, and the existence of a nondecreasing globally unique entropy function form the starting point of many textbook presentations of the foundations of thermodynamics. However, the thermal fluctuation phenomena associated with statistical mechanics has been argued to restrict the domain of validity of this basis of the second law of thermodynamics. Here we demonstrate that fluctuation phenomena can be incorporated into the traditional presentation, extending rather than restricting the domain of validity of the phenomenologically motivated second law. Consistency conditions lead to constraints upon the possible spectrum of thermal fluctuations. In a special case this uniquely selects the Gibbs canonical distribution and more generally incorporates the Tsallis distributions. No particular model of microscopic dynamics need be assumed.

  4. Solar Neutrons and Related Phenomena

    CERN Document Server

    Dorman, Lev


    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...

  5. New phenomena searches at CDF

    Energy Technology Data Exchange (ETDEWEB)

    Soha, Aron; /UC, Davis


    The authors report on recent results from the Collider Detector at Fermilab (CDF) experiment, which is accumulating data from proton-antiproton collisions with {radical}s = 1.96 TeV at Run II of the Fermilab Tevatron. The new phenomena being explored include Higgs, Supersymmetry, and large extra dimensions. They also present the latest results of searches for heavy objects, which would indicate physics beyond the Standard Model.

  6. Foot Anthropometry and Morphology Phenomena


    Agić, Ante; Nikolić, Vasilije; Mijović, Budimir


    Foot structure description is important for many reasons. The foot anthropometric morphology phenomena are analyzed together with hidden biomechanical functionality in order to fully characterize foot structure and function. For younger Croatian population the scatter data of the individual foot variables were interpolated by multivariate statistics. Foot structure descriptors are influenced by many factors, as a style of life, race, climate, and things of the great importance in ...

  7. Mathematical Modeling of Diverse Phenomena (United States)

    Howard, J. C.


    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.

  8. Particle-based modeling of heterogeneous chemical kinetics including mass transfer (United States)

    Sengar, A.; Kuipers, J. A. M.; van Santen, Rutger A.; Padding, J. T.


    Connecting the macroscopic world of continuous fields to the microscopic world of discrete molecular events is important for understanding several phenomena occurring at physical boundaries of systems. An important example is heterogeneous catalysis, where reactions take place at active surfaces, but the effective reaction rates are determined by transport limitations in the bulk fluid and reaction limitations on the catalyst surface. In this work we study the macro-micro connection in a model heterogeneous catalytic reactor by means of stochastic rotation dynamics. The model is able to resolve the convective and diffusive interplay between participating species, while including adsorption, desorption, and reaction processes on the catalytic surface. Here we apply the simulation methodology to a simple straight microchannel with a catalytic strip. Dimensionless Damkohler numbers are used to comment on the spatial concentration profiles of reactants and products near the catalyst strip and in the bulk. We end the discussion with an outlook on more complicated geometries and increasingly complex reactions.

  9. Transfers in heterogeneous environments; Transferts en milieux heterogenes

    Energy Technology Data Exchange (ETDEWEB)

    Flesselles, J.M. [Saint-Gobain Recherche, 93 - Aubervilliers (France); Gouesbet, G.; Mees, L.; Roze, C.; Girasole, Th.; Grehan, G. [Laboratoire d' Electromagnetisme et Systemes Particulaires (LESP), UMR CNRS 6614, CORIA. Universite de Rouen et INSA de Rouen, 76 - Saint-Etienne du Rouvray (France); Goyheneche, J.M.; Vignoles, G.; Coindreau, O. [Laboratoire des Composites Thermostructuraux (LCTS), UMR 5801, 33 - Pessac (France); Moyne, Ch. [LEMTA (UMR 7563) CNRS-INPL-UHP, 54 - Vandoeuvre les Nancy (France); Coussy, O. [Institut Navier - ENPC, 77 - Marne-la-Vallee (France); Lassabatere, Th. [Electricite de France Les Renardieres, Dept. Materiaux Mecanique des Composants, 77 - Moret sur Loing (France); Tadrist, L. [IUSTI - UMR 6595, 13 - Marseille (France)


    This document gathers the articles and transparencies of the invited talks given at the 2004 French congress of thermal engineering about transfers in heterogeneous environment. Content: transfer phenomena in industrial glass furnaces; simple and multiple scattering diagnosis by femto-second pulsed laser: application to particulate diagnoses; thermal modeling of thermo-structural composites; hybrid mixtures theory, average volumic measurement, periodical or stochastic homogenization: advance in scale change processes; thermo-hydro-chemical-mechanical coupling in porous medium: application to young concrete structures and to clay barriers of disposal facilities; transfers and flows in fluidization: recent advances and future challenges. (J.S.)

  10. Chemical transport reactions

    CERN Document Server

    Schäfer, Harald


    Chemical Transport Reactions focuses on the processes and reactions involved in the transport of solid or liquid substances to form vapor phase reaction products. The publication first offers information on experimental and theoretical principles and the transport of solid substances and its special applications. Discussions focus on calculation of the transport effect of heterogeneous equilibria for a gas motion between equilibrium spaces; transport effect and the thermodynamic quantities of the transport reaction; separation and purification of substances by means of material transport; and

  11. [Stochastic phenomena and the tumoral process]. (United States)

    Capp, Jean-Pascal


    In the reductionist perspective, genetic modifications are considered to initiate cancer. Their appearance is a stochastic phenomenon, but there are some biases linked to DNA sequence or exposure to mutagenic agents for instance. Cancer genome sequencing has shown a high inter- and intra-tumoral heterogeneity, sometimes questioning the genetic origin of cancer. Other stochastic processes are also studied in cancer, especially epigenetic modifications. They have a major role in diversifying phenotypes among cancer cells in the progression steps, but might also provide an alternative to genetic theories of cancer initiation. Nevertheless, the reductionist framework remains dominant here. Finally, stochastic cell-to-cell variations in gene expression constitute a third class of stochastic phenomena that can be considered as causal factors in cancer. Highlighting the role of high gene expression variability due to disruption of cellular interactions and communications allows avoiding reductionism by considering the interplay between genetic and tissue levels at every step of the disease. No organization level is privileged in this alternative theory. © 2014 médecine/sciences – Inserm.

  12. Phase transitions and critical phenomena

    CERN Document Server

    Domb, Cyril


    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

  13. Nonlinear Dynamic Phenomena in Mechanics

    CERN Document Server

    Warminski, Jerzy; Cartmell, Matthew P


    Nonlinear phenomena should play a crucial role in the design and control of engineering systems and structures as they can drastically change the prevailing dynamical responses. This book covers theoretical and applications-based problems of nonlinear dynamics concerned with both discrete and continuous systems of interest in civil and mechanical engineering. They include pendulum-like systems, slender footbridges, shape memory alloys, sagged elastic cables and non-smooth problems. Pendulums can be used as a dynamic absorber mounted in high buildings, bridges or chimneys. Geometrical nonlinear

  14. Violent phenomena in the Universe

    CERN Document Server

    Narlikar, Jayant V


    The serenity of a clear night sky belies the evidence-gathered by balloons, rockets, satellites, and telescopes-that the universe contains centers of furious activity that pour out vast amounts of energy, some in regular cycles and some in gigantic bursts. This reader-friendly book, acclaimed by Nature as ""excellent and uncompromising,"" traces the development of modern astrophysics and its explanations of these startling celestial fireworks.This lively narrative ranges from the gravitational theories of Newton and Einstein to recent exciting discoveries of such violent phenomena as supernova

  15. Phase transitions and critical phenomena

    CERN Document Server

    Domb, Cyril


    The field of phase transitions and critical phenomena continues to be active in research, producing a steady stream of interesting and fruitful results. No longer an area of specialist interest, it has acquired a central focus in condensed matter studies. 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 information on important recent developments.The two review articles in this volume complement each other in a remarkable way. Both deal with what m

  16. Quantum theory of collective phenomena

    CERN Document Server

    Sewell, G L


    ""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

  17. Phenomena and Diosignes of Aratous (United States)

    Avgoloupis, S. I.


    Aratous (305-240B.C.) was a singular intellectual, writer and poet which engage himself to compose a very interesting astronomical poet, using the "Dactylous sixstage' style, the formal style of the ancient Greek Epic poetry. This astronomic poem of Aratous "Phenomena and Diosignes" became very favorite reading during the Alexandrine, the Romman and the Byzandin eras as well and had received many praises from significant poets and particularly from Hipparchous and from Theonas from Alexandria, an astronomer of 4rth century A.C.(in Greeks)

  18. Musical obsessions: a comprehensive review of neglected clinical phenomena. (United States)

    Taylor, Steven; McKay, Dean; Miguel, Euripedes C; De Mathis, Maria Alice; Andrade, Chittaranjan; Ahuja, Niraj; Sookman, Debbie; Kwon, Jun Soo; Huh, Min Jung; Riemann, Bradley C; Cottraux, Jean; O'Connor, Kieron; Hale, Lisa R; Abramowitz, Jonathan S; Fontenelle, Leonardo F; Storch, Eric A


    Intrusive musical imagery (IMI) consists of involuntarily recalled, short, looping fragments of melodies. Musical obsessions are distressing, impairing forms of IMI that merit investigation in their own right and, more generally, research into these phenomena may broaden our understanding of obsessive-compulsive disorder (OCD), which is phenomenologically and etiologically heterogeneous. We present the first comprehensive review of musical obsessions, based on the largest set of case descriptions ever assembled (N=96). Characteristics of musical obsessions are described and compared with normal IMI, musical hallucinations, and visual obsessional imagery. Assessment, differential diagnosis, comorbidity, etiologic hypotheses, and treatments are described. Musical obsessions may be under-diagnosed because they are not adequately assessed by current measures of OCD. Musical obsessions have been misdiagnosed as psychotic phenomena, which has led to ineffective treatment. Accurate diagnosis is important for appropriate treatment. Musical obsessions may respond to treatments that are not recommended for prototypic OCD symptoms. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Composite Transport Model and Water and Solute Transport across Plant Roots: An Update

    Directory of Open Access Journals (Sweden)

    Yangmin X. Kim


    Full Text Available The present review examines recent experimental findings in root transport phenomena in terms of the composite transport model (CTM. It has been a well-accepted conceptual model to explain the complex water and solute flows across the root that has been related to the composite anatomical structure. There are three parallel pathways involved in the transport of water and solutes in roots – apoplast, symplast, and transcellular paths. The role of aquaporins (AQPs, which facilitate water flows through the transcellular path, and root apoplast is examined in terms of the CTM. The contribution of the plasma membrane bound AQPs for the overall water transport in the whole plant level was varying depending on the plant species, age of roots with varying developmental stages of apoplastic barriers, and driving forces (hydrostatic vs. osmotic. Many studies have demonstrated that the apoplastic barriers, such as Casparian bands in the primary anticlinal walls and suberin lamellae in the secondary cell walls, in the endo- and exodermis are not perfect barriers and unable to completely block the transport of water and some solute transport into the stele. Recent research on water and solute transport of roots with and without exodermis triggered the importance of the extension of conventional CTM adding resistances that arrange in series (epidermis, exodermis, mid-cortex, endodermis, and pericycle. The extension of the model may answer current questions about the applicability of CTM for composite water and solute transport of roots that contain complex anatomical structures with heterogeneous cell layers.

  20. Natural phenomena hazards, Hanford Site, Washington

    Energy Technology Data Exchange (ETDEWEB)

    Conrads, T.J.


    This document presents the natural phenomena hazard loads for use in implementing DOE Order 5480.28, Natural Phenomena Hazards Mitigation, and supports development of double-shell tank systems specifications at the Hanford Site in south-central Washington State. The natural phenomena covered are seismic, flood, wind, volcanic ash, lightning, snow, temperature, solar radiation, suspended sediment, and relative humidity.

  1. Earthquake prediction with electromagnetic phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Hayakawa, Masashi, E-mail: [Hayakawa Institute of Seismo Electomagnetics, Co. Ltd., University of Electro-Communications (UEC) Incubation Center, 1-5-1 Chofugaoka, Chofu Tokyo, 182-8585 (Japan); Advanced Wireless & Communications Research Center, UEC, Chofu Tokyo (Japan); Earthquake Analysis Laboratory, Information Systems Inc., 4-8-15, Minami-aoyama, Minato-ku, Tokyo, 107-0062 (Japan); Fuji Security Systems. Co. Ltd., Iwato-cho 1, Shinjyuku-ku, Tokyo (Japan)


    Short-term earthquake (EQ) prediction is defined as prospective prediction with the time scale of about one week, which is considered to be one of the most important and urgent topics for the human beings. If this short-term prediction is realized, casualty will be drastically reduced. Unlike the conventional seismic measurement, we proposed the use of electromagnetic phenomena as precursors to EQs in the prediction, and an extensive amount of progress has been achieved in the field of seismo-electromagnetics during the last two decades. This paper deals with the review on this short-term EQ prediction, including the impossibility myth of EQs prediction by seismometers, the reason why we are interested in electromagnetics, the history of seismo-electromagnetics, the ionospheric perturbation as the most promising candidate of EQ prediction, then the future of EQ predictology from two standpoints of a practical science and a pure science, and finally a brief summary.

  2. Critical Phenomena in Gravitational Collapse

    Directory of Open Access Journals (Sweden)

    Martín-García José M.


    Full Text Available As first discovered by Choptuik, the black hole threshold in the space of initial data for general relativity shows both surprising structure and surprising simplicity. Universality, power-law scaling of the black hole mass, and scale echoing have given rise to the term “critical phenomena”. They are explained by the existence of exact solutions which are attractors within the black hole threshold, that is, attractors of codimension one in phase space, and which are typically self-similar. Critical phenomena give a natural route from smooth initial data to arbitrarily large curvatures visible from infinity, and are therefore likely to be relevant for cosmic censorship, quantum gravity, astrophysics, and our general understanding of the dynamics of general relativity.

  3. Remote sensing of natural phenomena

    Directory of Open Access Journals (Sweden)

    Miodrag D. Regodić


    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

  4. Upscaling of permeability in Shale with Heterogeneous Kerogen Distribution (United States)

    Cao, G.; Lin, M.


    Apparent permeability is a vital parameter for accurate estimation of exploitable gas reserve in shale. In this paper, we introduce a new model to investigate multi-scale gas-transport phenomena in organic-rich-shale with heterogeneous kerogen distribution. The formulation is decomposed into two subdomains: kerogen and inorganic matrix. On the one hand, considering the molecular phenomena (slip and diffusive transport) is significant in kerogen for its enrichment of nanopores, we use pore-scale network model (PNM) to represent it and apply Javadpour's apparent permeability formula(2009) to calculate flow in the nanoscale throats. On the other hand, inorganic matrix, with relatively large pores, micro natural fractures and manual hydraulic fracturing cracks, its flow is approximate to Darcy, so we model it as continuum-scale models FVM. The two subdomains are coupled using mortars. Mortars are finite-element spaces employed to couple independent subdomains by ensuring interfacial pressures and fluxes are matched. Considering the local heterogeneities, kerogen is treated as several nanoporous organic material blocks randomly dispersed within the inorganic matrix. We study on four factors: the distribution of kerogen, the permeability of inorganic matrix (Ki), the magnitude of pressure, and the TOC of coupling model. The results are shown intuitively by APF (apparent permeability function) graph. We conclude that: (1) when Ki is greater than the Darcy permeability of kerogen, the APF graphs with different TOC and distribution have an intersection point, and this point is only decided by permeability of Ki and the pore size distribution of kerogen; (2) when pressure is close to or higher than the pressure of intersection point, the influence of heterogeneous distribution can be ignored, and the complex coupling model can instead by a simple equivalent model. This work is supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB

  5. Targeting population heterogeneity for optimal cell factories

    DEFF Research Database (Denmark)

    Heins, Anna-Lena; Carlqvist, Magnus; Helmark, S.

    To achieve an efficient production process, it is essential to optimize both the strain and the cultivation conditions. Traditionally, a microbial population has been considered homogeneous in optimization studies of fermentation processes. However, research has shown that a typical microbial...... population in a fermentor is heterogeneous. There are indications that such heterogeneity may be both beneficial (facilitates quick adaptation to new conditions) and harmful (reduces yields and productivities) for the robustness of the fermentation process. Significant gradients of e.g. dissolved oxygen...... the heterogeneity level of the population. To further investigate these phenomena and gain a deeper understanding of population heterogeneity, Saccharomyces cerevisiae growth reporter strains based on the expression of green fluorescent protein (GFP) were constructed which enabled us to perform single cell level...

  6. EDITORIAL: Quantum phenomena in Nanotechnology Quantum phenomena in Nanotechnology (United States)

    Loss, Daniel


    Twenty years ago the Institute of Physics launched the journal Nanotechnology from its publishing house based in the home town of Paul Dirac, a legendary figure in the development of quantum mechanics at the turn of the last century. At the beginning of the 20th century, the adoption of quantum mechanical descriptions of events transformed the existing deterministic world view. But in many ways it also revolutionised the progress of research itself. For the first time since the 17th century when Francis Bacon established inductive reasoning as the means of advancing science from fact to axiom to law, theory was progressing ahead of experiments instead of providing explanations for observations that had already been made. Dirac's postulation of antimatter through purely theoretical investigation before its observation is the archetypal example of theory leading the way for experiment. The progress of nanotechnology and the development of tools and techniques that enabled the investigation of systems at the nanoscale brought with them many fascinating observations of phenomena that could only be explained through quantum mechanics, first theoretically deduced decades previously. At the nanoscale, quantum confinement effects dominate the electrical and optical properties of systems. They also render new opportunities for manipulating the response of systems. For example, a better understanding of these systems has enabled the rapid development of quantum dots with precisely determined properties, which can be exploited in a range of applications from medical imaging and photovoltaic solar cells to quantum computation, a radically new information technology being currently developed in many labs worldwide. As the first ever academic journal in nanotechnology, {\\it Nanotechnology} has been the forum for papers detailing progress of the science through extremely exciting times. In the early years of the journal, the investigation of electron spin led to the formulation

  7. Uncovering noisy social signals : Using optimization methods from experimental physics to study social phenomena

    NARCIS (Netherlands)

    Kaptein, M.C.; Van Emden, Robin; Iannuzzi, Davide


    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

  8. Uncovering noisy social signals: Using optimization methods from experimental physics to study social phenomena

    NARCIS (Netherlands)

    Kaptein, M.C.; Emden, R. van; Iannuzzi, D.


    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

  9. Interface-induced phenomena in magnetism (United States)

    Hellman, Frances; Hoffmann, Axel; Tserkovnyak, Yaroslav; Beach, Geoffrey S. D.; Fullerton, Eric E.; Leighton, Chris; MacDonald, Allan H.; Ralph, Daniel C.; Arena, Dario A.; Dürr, Hermann A.; Fischer, Peter; Grollier, Julie; Heremans, Joseph P.; Jungwirth, Tomas; Kimel, Alexey V.; Koopmans, Bert; Krivorotov, Ilya N.; May, Steven J.; Petford-Long, Amanda K.; Rondinelli, James M.; Samarth, Nitin; Schuller, Ivan K.; Slavin, Andrei N.; Stiles, Mark D.; Tchernyshyov, Oleg; Thiaville, André; Zink, Barry L.


    This article reviews static and dynamic interfacial effects in magnetism, focusing on interfacially driven magnetic effects and phenomena associated with spin-orbit coupling and intrinsic symmetry breaking at interfaces. It provides a historical background and literature survey, but focuses on recent progress, identifying the most exciting new scientific results and pointing to promising future research directions. It starts with an introduction and overview of how basic magnetic properties are affected by interfaces, then turns to a discussion of charge and spin transport through and near interfaces and how these can be used to control the properties of the magnetic layer. Important concepts include spin accumulation, spin currents, spin-transfer torque, and spin pumping. An overview is provided to the current state of knowledge and existing review literature on interfacial effects such as exchange bias, exchange-spring magnets, the spin Hall effect, oxide heterostructures, and topological insulators. The article highlights recent discoveries of interface-induced magnetism and noncollinear spin textures, nonlinear dynamics including spin-transfer torque and magnetization reversal induced by interfaces, and interfacial effects in ultrafast magnetization processes.

  10. Interface-Induced Phenomena in Magnetism. (United States)

    Hellman, Frances; Hoffmann, Axel; Tserkovnyak, Yaroslav; Beach, Geoffrey S D; Fullerton, Eric E; Leighton, Chris; MacDonald, Allan H; Ralph, Daniel C; Arena, Dario A; Dürr, Hermann A; Fischer, Peter; Grollier, Julie; Heremans, Joseph P; Jungwirth, Tomas; Kimel, Alexey V; Koopmans, Bert; Krivorotov, Ilya N; May, Steven J; Petford-Long, Amanda K; Rondinelli, James M; Samarth, Nitin; Schuller, Ivan K; Slavin, Andrei N; Stiles, Mark D; Tchernyshyov, Oleg; Thiaville, André; Zink, Barry L


    This article reviews static and dynamic interfacial effects in magnetism, focusing on interfacially-driven magnetic effects and phenomena associated with spin-orbit coupling and intrinsic symmetry breaking at interfaces. It provides a historical background and literature survey, but focuses on recent progress, identifying the most exciting new scientific results and pointing to promising future research directions. It starts with an introduction and overview of how basic magnetic properties are affected by interfaces, then turns to a discussion of charge and spin transport through and near interfaces and how these can be used to control the properties of the magnetic layer. Important concepts include spin accumulation, spin currents, spin transfer torque, and spin pumping. An overview is provided to the current state of knowledge and existing review literature on interfacial effects such as exchange bias, exchange spring magnets, spin Hall effect, oxide heterostructures, and topological insulators. The article highlights recent discoveries of interface-induced magnetism and non-collinear spin textures, non-linear dynamics including spin torque transfer and magnetization reversal induced by interfaces, and interfacial effects in ultrafast magnetization processes.

  11. Understanding empathy and related phenomena. (United States)

    Shamasundar, C


    Over a period of time, the author arrived at a few tentative postulates concerning empathy and related processes based on some of his experiences and observations. The central theme of these postulates is, firstly, that interpersonal interaction is an interaction of the personal-space fields. Secondly, empathy, therapeutic benefit, and the professional stress are all related to the same process of interpersonal interaction. This interaction takes place as an enmeshment of personal spaces of the interacting individuals, and involves transfer of a wide range of information in the affective, cognitive, and other areas. This is because the personal spaces have fieldlike qualities analogous to what Kurt Lewin described. Thus, such phenomena as empathy, therapeutic benefit, professional stress are all consequences of the same process. It is possible to substantiate these postulates by diverse evidences in the published literature. The natural consequences of such an interpersonal interaction are empathic understanding, transfer of mood states (like hope, distress or expectancy), affective states (like anxiety, sadness, anger or hostility), ideas, images and even attitudes and values, etc. This phenomenon of transfer can explain such processes as therapeutic benefit in individual and group settings, professional stress, shared delusions, and even experimenter bias. Whether one becomes aware of such transferred information or not depends upon the intent and sensitivity of the participants.

  12. Critical Phenomena in Population Coding (United States)

    Berkowitz, John; Sharpee, Tatyana


    Populations of neurons that code for sensory stimuli are often modeled as having sigmoidal tuning curves where the midpoint and slope of the curve represent, respectively, an intrinsic firing threshold and noise level. Recent studies have shown for two subpopulations of neurons that states below a critical noise level are associated with symmetry breaking between the populations' thresholds. In this work we consider the case of up to seven distinct subpopulations encoding a common gaussian stimulus. We optimized the mutual information between output patterns and stimuli by adjusting the thresholds for a fixed noise level. In the high-noise regime the optimal thresholds are fully redundant whereas the low noise limit predicts distinct threshold values that achieve histogram equalization of the input signal. Between the two limits, the thresholds exhibit a complex branching process that occur at successive values of the noise level. Each branch corresponds to a critical point of a continuous phase transition. The behavior of the system in the limit of a large number of subpopulations is also investigated, and critical phenomena are also present in the distribution of thresholds in this limit.

  13. Sketching Biological Phenomena and Mechanisms. (United States)

    Sheredos, Benjamin; Bechtel, William


    In many fields of biology, both the phenomena to be explained and the mechanisms proposed to explain them are commonly presented in diagrams. Our interest is in how scientists construct such diagrams. Researchers begin with evidence, typically developed experimentally and presented in data graphs. To arrive at a robust diagram of the phenomenon or the mechanism, they must integrate a variety of data to construct a single, coherent representation. This process often begins as the researchers create a first sketch, and it continues over an extended period as they revise the sketch until they arrive at a diagram they find acceptable. We illustrate this process by examining the sketches developed in the course of two research projects directed at understanding the generation of circadian rhythms in cyanobacteria. One identified a new aspect of the phenomenon itself, whereas the other aimed to develop a new mechanistic account. In both cases, the research resulted in a paper in which the conclusion was presented in a diagram that the authors deemed adequate to convey it. These diagrams violate some of the normative "cognitive design principles" advanced by cognitive scientists as constraints on successful visual communication. We suggest that scientists' sketching is instead governed by norms of success that are broadly explanatory: conveying the phenomenon or mechanism. Copyright © 2017 Cognitive Science Society, Inc.

  14. Mixed Fluid Conditions: Capillary Phenomena

    KAUST Repository

    Santamarina, Carlos


    Mixed fluid phenomena in porous media have profound implications on soil-atmosphere interaction, energy geotechnology, environmental engineering and infrastructure design. Surface tension varies with pressure, temperature, solute concentration, and surfactant concentration; on the other hand, the contact angle responds to interfacial tensions, surface topography, invasion velocity, and chemical interactions. Interfaces are not isolated but interact through the fluid pressure and respond to external fields. Jumps, snap-offs and percolating wetting liquids along edges and crevices are ubiquitous in real, non-cylindrical porous networks. Pore- and macroscale instabilities together with pore structure variability-and-correlation favor fluid trapping and hinder recovery efficiency. The saturation-pressure characteristic curve is affected by the saturation-history, flow-rate, the mechanical response of the porous medium, and time-dependent reactive and diffusive processes; in addition, there are salient differences between unsaturation by internal gas nucleation and gas invasion. Capillary forces add to other skeletal forces in the porous medium and can generate open-mode discontinuities when the capillary entry pressure is high relative to the effective stress. Time emerges as an important variable in mixed-fluid conditions and common quasi-static analyses may fail to capture the system response.

  15. Transport phenomena in capillary-porous structures and heat pipes

    CERN Document Server

    Smirnov, Henry


    With emphasis on the processes involved, this text explores the experimental efforts in two-phase thermal control technology research and development. This work evaluates and compares different theoretical approaches, experimental results, and models, such as semi-empirical models for critical boiling heat fluxes.

  16. Thermo-hydrodynamic transport phenomena in partially wetting ...

    Indian Academy of Sciences (India)

    Vyas Srinivasan

    channels has increased due to emerging applications in diverse branches ranging from .... plug, observed when the solid is not pre-wetted by liquid and there is no thin-film around the gas slug, leading to the formation of three- phase contact line [75]. 608 ... given by Young's law as follows: rlv cos heq ¼ rsv ю rsl. П4ч.

  17. Transport Phenomena in Liquid Foams and Liquid Marble Colloids


    Attia, Joseph


    Liquid foams consist of randomly packed bubbles separated by a thin liquid fluid. They can be found in various industrial applications including separation processes, oil recovery, water treatment, food, and material processings. They are also being considered as coolant in heat exchangers systems for heat transfer enhancement compared with single-phase air. Similarly, liquid marbles, a phase inversion of liquid foams, consisting of a liquid core stabilized by closely packed solid hydrophobic...

  18. Nonlinear phenomena, turbulence and anomalous transport in fusion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Hidalgo, C.; Estrada, T.; Sanchez, E.; Branas, B.; Garcia-Cortes, I.; Van Milligen, B.P.; Balbin, R.; Pedrosa, M.A.; Sanchez, J. [Asociancion Euratom-Ciemat, Madrid (Spain); Carreras, B.A. [Oak Ridge National Lab., TN (United States)] [and others


    The nonlinear nature of the plasma turbulence, as measured by bicoherence analysis, has been studied in stellarator (ATF and W7AS) and tokamak (PBXM) devices. In ATF, little nonlinear interaction is found in the scrape-off layer region whereas the strength of the coupling is enhanced in the edge plasma region where the level of fluctuations is consistent with the theoretical expectations from resistive interchange modes. In W7AS the level of bicoherence is significantly smaller than in ATF. The comparison ATF/W7AS/PBXM suggest the important role of the magnetic shear to determine nonlinear behavior of the turbulence. The level of bicoherence also depends on the plasma conditions: in particular, it increases at the H-mode transition. The comparison between the nonlinear behavior of the turbulence in tokamaks and stellarators allows experimental verification of theoretical turbulence models.

  19. Measurements of Electrical Transport Phenomena in Semiconductor Materials. (United States)


    experimental system. 67 3.2 Detailed view of experiment section. 68 3.3 Top view and cross-sections of various test structures. 71 3.4 Interceram model...low leakage) were mounted in Interceram model #AV-170 X-band Gunn diode packages (Figure 3.4a) with Epo-Tek H20-E conductive epoxy. This two component...012 .054 3-48 " .133 ALL DIMENSIONS IN INCHES Figure 3.4. Interceram model #AV-170 microwave diode package. 76 variation of depletion width (i.e

  20. [Study of multicomponent diffusion and transport phenomena]. Progress report

    Energy Technology Data Exchange (ETDEWEB)


    The major activities in this period are the percolation threshold in electronic conduction in {beta}-alumina type solid electrolytes, mixed alkali effects in ion conducting binary glasses, chemical diffusion problems, semiconductors, and relaxation process in diffusion. The last one constitutes the recent progress.

  1. Transport phenomena in gas-selective silica membranes

    DEFF Research Database (Denmark)

    Boffa, Vittorio

    Upcoming technology platforms for green fuel production require the development of advanced molecular separation processes for recovering dry liquid biofuels [1,2], biomethane [2] and hydrogen [3]. Replacement of extractive distillation, cryodistillation and adsorption processes by membrane units...... may lead to vast energy savings [2,3]. In this context, ultramicroporous silica membranes, that is, silica membranes with pores smaller than 1 nm [4], appear to be able to play a determinant role. Indeed, in reason of their extremely small pore size, these membranes can be used as sieves to recover...... fluxes than zeolite membranes. Ultramicroporous silica membranes typical typically an asymmetric structure, consisting of few millimeters thick macroporous tubes or disks, which confer mechanical strength to the membrane, and one or more mesoporous intermediate layers with subsequently smaller pore sizes...

  2. Modeling Supply Chains and Business Cycles as Unstable Transport Phenomena


    Helbing, Dirk


    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 ``bullwhip 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 consumptio...

  3. Maxwell Prize Talk: Scaling Laws for the Dynamical Plasma Phenomena (United States)

    Ryutov, Livermore, Ca 94550, Usa, D. D.


    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.

  4. Observation of Celestial Phenomena in Ancient China (United States)

    Sun, Xiaochun

    Because of the need for calendar-making and portent astrology, the Chinese were diligent and meticulous observers of celestial phenomena. China has maintained the longest continuous historical records of celestial phenomena in the world. Extraordinary or abnormal celestial events were particularly noted because of their astrological significance. The historical records cover various types of celestial phenomena, which include solar and lunar eclipses, sunspots, "guest stars" (novae or supernovae as we understand today), comets and meteors, and all kinds of planetary phenomena. These records provide valuable historical data for astronomical studies today.

  5. Exponential analysis in physical phenomena (United States)

    Istratov, Andrei A.; Vyvenko, Oleg F.


    Many physical phenomena are described by first-order differential equations whose solution is an exponential decay. Determining the time constants and amplitudes of exponential decays from the experimental data is a common task in semiconductor physics (deep level transient spectroscopy), biophysics (fluorescence decay analysis), nuclear physics and chemistry (radioactive decays, nuclear magnetic resonance), chemistry and electrochemistry (reaction kinetics) and medical imaging. This review article discusses the fundamental mathematical limitations of exponential analysis, outlines the critical aspects of acquisition of exponential transients for subsequent analysis, and gives a comprehensive overview of numerical algorithms used in exponential analysis. In the first part of the article the resolution of exponential analysis as a function of noise in input decays is discussed. It is shown that two exponential decays can be resolved in a transient only if the ratio of their time constants is greater than the resolution limit, which can be explicitly calculated from the signal-to-noise ratio in the transient. Although the signal-to-noise ratio is generally limited by the sensitivity of the equipment, it is shown that digitalization of the decays may be a major source of noise. The requirements for type of analog-to-digital converter, number of digitized data points and duration of digitized transients, which must be met to obtain the theoretical resolution limit and to improve stability of the exponential analysis, are formulated. The second part of the review article gives an overview and comparison of major numerical techniques of exponential analysis, such as the nonlinear least squares fit, the Prony method, the method of modulating functions, the method of moments, the Laplace-Padé approximation, the Tikhonov regularization method, the Gardner transformation, the method of maximum entropy and others.

  6. Simulation of Magnetic Phenomena at Realistic Interfaces

    KAUST Repository

    Grytsyuk, Sergiy


    In modern technology exciting developments are related to the ability to understand and control interfaces. Particularly, magnetic interfaces revealing spindependent electron transport are of great interest for modern spintronic devices, such as random access memories and logic devices. From the technological point of view, spintronic devices based on magnetic interfaces enable manipulation of the magnetism via an electric field. Such ability is a result of the different quantum effects arising from the magnetic interfaces (for example, spin transfer torque or spin-orbit torque) and it can reduce the energy consumption as compared to the traditional semiconductor electronic devices. Despite many appealing characteristics of these materials, fundamental understanding of their microscopic properties and related phenomena needs to be established by thorough investigation. In this work we implement first principles calculations in order to study the structural, electric, and magnetic properties as well as related phenomena of two types of interfaces with large potential in spintronic applications: 1) interfaces between antiferromagnetic 3d-metal-oxides and ferromagnetic 3d-metals and 2) interfaces between non-magnetic 5d(4d)- and ferromagnetic 3d-metals. A major difficulty in studying such interfaces theoretically is the typically large lattice mismatch. By employing supercells with Moir e patterns, we eliminate the artificial strain that leads to doubtful results and are able to describe the dependence of the atomic density at the interfaces on the component materials and their thicknesses. After establishing understanding about the interface structures, we investigate the electronic and magnetic properties. A Moir e supercell with transition layer is found to reproduce the main experimental findings and thus turns out to be the appropriate model for simulating magnetic misfit interfaces. In addition, we systematically study the magnetic anisotropy and Rashba band

  7. Preface: MHD wave phenomena in the solar interior and atmosphere (United States)

    Fedun, Viktor; Srivastava, A. K.


    The Sun is our nearest star and this star produces various plasma wave processes and energetic events. These phenomena strongly influence interplanetary plasma dynamics and contribute to space-weather. The understanding of solar atmospheric dynamics requires hi-resolution modern observations which, in turn, further advances theoretical models of physical processes in the solar interior and atmosphere. In particular, it is essential to connect the magnetohydrodynamic (MHD) wave processes with the small and large-scale solar phenomena vis-a-vis transport of energy and mass. With the advent of currently available and upcoming high-resolution space (e.g., IRIS, SDO, Hinode, Aditya-L1, Solar-C, Solar Orbiter), and ground-based (e.g., SST, ROSA, NLST, Hi-C, DKIST, EST, COSMO) observations, solar physicists are able to explore exclusive wave processes in various solar magnetic structures at different spatio-temporal scales.

  8. Millisecond phenomena in mass accreting neutron stars

    NARCIS (Netherlands)

    van der Klis, M.; Cohen, L.


    The past twelve years have seen the discovery, with NASA's Rossi X-ray Timing Explorer (RXTE), of several long-predicted phenomena associated with the accretion of matter onto a neutron star in a binary (double) star system. These phenomena are observed in the strong X-ray emission produced by these

  9. Autogenous Phenomena in Cement-Based Materials

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede

    This thesis has been written to obtain the Danish doctoral degree in technology, Dr.Techn. It addresses autogenous phenomena in cement-based materials - primarily deformation and change of the relative humidity (RH). In the thesis it is explained how the importance of these phenomena was identified...

  10. Electrical breakdown phenomena of dielectric elastomers

    DEFF Research Database (Denmark)

    Mateiu, Ramona Valentina; Yu, Liyun; Skov, Anne Ladegaard


    years. However, optimization with respect to the dielectric permittivity solely may lead to other problematic phenomena such as premature electrical breakdown. In this work, we investigate the electrical breakdown phenomena of various types of permittivity-enhanced silicone elastomers. Two types...

  11. PREFACE Integrability and nonlinear phenomena Integrability and nonlinear phenomena (United States)

    Gómez-Ullate, David; Lombardo, Sara; Mañas, Manuel; Mazzocco, Marta; Nijhoff, Frank; Sommacal, Matteo


    Back in 1967, Clifford Gardner, John Greene, Martin Kruskal and Robert Miura published a seminal paper in Physical Review Letters which was to become a cornerstone in the theory of integrable systems. In 2006, the authors of this paper received the AMS Steele Prize. In this award the AMS pointed out that `In applications of mathematics, solitons and their descendants (kinks, anti-kinks, instantons, and breathers) have entered and changed such diverse fields as nonlinear optics, plasma physics, and ocean, atmospheric, and planetary sciences. Nonlinearity has undergone a revolution: from a nuisance to be eliminated, to a new tool to be exploited.' From this discovery the modern theory of integrability bloomed, leading scientists to a deep understanding of many nonlinear phenomena which is by no means reachable by perturbation methods or other previous tools from linear theories. Nonlinear phenomena appear everywhere in nature, their description and understanding is therefore of great interest both from the theoretical and applicative point of view. If a nonlinear phenomenon can be represented by an integrable system then we have at our disposal a variety of tools to achieve a better mathematical description of the phenomenon. This special issue is largely dedicated to investigations of nonlinear phenomena which are related to the concept of integrability, either involving integrable systems themselves or because they use techniques from the theory of integrability. The idea of this special issue originated during the 18th edition of the Nonlinear Evolution Equations and Dynamical Systems (NEEDS) workshop, held at Isola Rossa, Sardinia, Italy, 16-23 May 2009 ( The issue benefits from the occasion offered by the meeting, in particular by its mini-workshops programme, and contains invited review papers and contributed papers. It is worth pointing out that there was an open call for papers and all contributions were peer reviewed

  12. [Review on landscape heterogeneity]. (United States)

    Zhao, Yutao; Yu, Xinxiao; Guang, Wenbin


    On the base of precedent studies, the occurring mechanism, classification, measurement methods, and the important role of landscape heterogeneity in landscape ecology were reviewed. The inner and outer uncertain factors result in landscape heterogeneity. Landscape heterogeneity has close relations with landscape stability, landscape design, architecture, management and disturbance, scale and ecological diversity in ecology. Complexity of landscape heterogeneity research, non-system of measurement indices and methods, difficulties and limitations of landscape heterogeneity modelling were all discussed respectively. In addition, it is suggested that the theory and methods of ecological complexity should be used to improve landscape heterogeneity research.

  13. Particle Transport Simulation on Heterogeneous Hardware

    CERN Multimedia

    CERN. Geneva


    CPUs and GPGPUs. About the speaker Vladimir Koylazov is CTO and founder of Chaos Software and one of the original developers of the V-Ray raytracing software. Passionate about 3D graphics and programming, Vlado is the driving force behind Chaos Group's software solutions. He participated in the implementation of algorithms for accurate light simulations and support for different hardware platforms, including CPU and GPGPU, as well as distributed calculat...

  14. Understanding the Physics of changing mass phenomena (United States)

    Ellermeijer, A. L.


    Changing mass phenomena, like a falling chain or a bungee jumper, might give surprising results, even for experienced physicists. They have resulted in hot discussions in journals, in which for instance Physics professors claim the impossibility of an acceleration larger then g in case of a bungee jumper. These phenomena are also interesting as topics for challenging student projects, and used as such by Dutch high school students. I will take these phenomena as the context in which I like to demonstrate the possibilities of ICT in the learning process of physics. Especially dynamical modeling enables us to describe these phenomena in an elegant way and with knowledge of high school mathematics. Furthermore tools for video-analysis and data from measurements with sensors allow us to study the phenomena in experiments. This example demonstrates the level of implementation of ICT in Physics Education in The Netherlands [1].

  15. Precedent Phenomena in Quebecois Linguistic World View

    Directory of Open Access Journals (Sweden)

    Ксения Эдуардовна Болотина


    Full Text Available This article is devoted to the linguocultural analysis of precedent phenomena as parts of Quebecois’ cognitive base. Precedent phenomena being cultural facts are one of the key issues in modern linguistic and cognitive studies. By precedent phenomena we mean, according to Y.E. Prohorov, such entities when verbalized in discourse that refer to a certain cultural fact behind them. In the article the precedent phenomena such as precedent text, precedent situation, precedent utterance, and precedent name are analyzed. The main theses of the precedence theory given in the article (Y.N. Karaulov, Y.E. Prohorov, V.V. Krasnyh, D.B. Gudkov are at the heart of precedence studies on the basis of different languages. However, a complex analysis of precedent phenomena in the Quebec national variant of French is new to Russian linguistics. The study of precedent phenomena enables us to elicit features of their functioning in ethnospecific discourse and determine cultural dominants existing in Quebecois’ linguistic world view. Given the fact that the size of the article is limited, we undertooke the analysis of eight phenomena precedent of the bearers of Quebec linguoculture. The choice of phenomena is determined by the frequency of their use in discourse. The facts analyzed are of national character, i.e. known to all members of the linguocultural community. A certain cultural fact is at the very core of each precedent phenomenon given in the article. To get the whole picture we analysed historic, political, and cultural context connected to the precedent phenomena in question. The study enables us to elicit distinctive features that are at the core of each phenomenon. The results are backed with the supportive material drawn from analysis of different types of discourse. The analysis of precedent phenomena undertaken in this article allows us to reconstruct, to a certain extent, Quebec cultural space and is a stepping stone to the reconstruction of the

  16. Link-Heterogeneity vs. Node-Heterogeneity in Clusters


    Beaumont, Olivier; Rosenberg, Arnold


    International audience; Heterogeneity in resources pervades all modern computing platforms. How do the effects of heterogeneity depend on which resources differ among computers in a platform? Some answers are derived within a formal framework, by comparing heterogeneity in computing power (node-heterogeneity) with heterogeneity in communication speed (link-heterogeneity). The former genre of heterogeneity seems much easier to understand than the latter.

  17. Heterogeneous network architectures

    DEFF Research Database (Denmark)

    Christiansen, Henrik Lehrmann


    Future networks will be heterogeneous! Due to the sheer size of networks (e.g., the Internet) upgrades cannot be instantaneous and thus heterogeneity appears. This means that instead of trying to find the olution, networks hould be designed as being heterogeneous. One of the key equirements here...

  18. Fourteenth International Conference on Ultrafast Phenomena

    CERN Document Server

    Kobayashi, Takayoshi; Kobayashi, Tetsuro; Nelson, Keith A; Silvestri, Sandro; Ultrafast Phenomena XIV


    Ultrafast Phenomena XIV presents the latest advances in ultrafast science, including ultrafast laser and measurement technology as well as studies of ultrafast phenomena. Pico-, femto-, and atosecond processes relevant in physics, chemistry, biology and engineering are presented. Ultrafast technology is now having a profound impact within a wide range of applications, among them imaging, material diagnostics, and transformation and high-speed optoelectronics. This book summarizes results presented at the 14th Ultrafast Phenomena Conference and reviews the state of the art in this important and rapidly advancing field.

  19. Transient phenomena in electrical power systems

    CERN Document Server

    Venikov, V A; Higinbotham, W


    Electronics and Instrumentation, Volume 24: Transient Phenomena in Electrical Power Systems presents the methods for calculating the stability and the transient behavior of systems with forced excitation control. This book provides information pertinent to the analysis of transient phenomena in electro-mechanical systems.Organized into five chapters, this volume begins with an overview of the principal requirements in an excitation system. This text then explains the electromagnetic and electro-mechanical phenomena, taking into account the mutual action between the components of the system. Ot

  20. Developing Phenomena Models from Experimental Data

    DEFF Research Database (Denmark)

    Kristensen, Niels Rode; Madsen, Henrik; Jørgensen, Sten Bay


    unknown functionality behind various phenomena in first engineering principles models using experimental data. The proposed modelling approach has significant application potential, e.g. for determining unknown reaction kinetics in both chemical and biological processes. To illustrate the performance......A systematic approach for developing phenomena models from experimental data is presented. The approach is based on integrated application of stochastic differential equation (SDE) modelling and multivariate nonparametric regression, and it is shown how these techniques can be used to uncover...... of the approach, a case study is presented, which shows how an appropriate phenomena model for the growth rate of biomass in a fed-batch bioreactor can be inferred from data....

  1. Developing Phenomena Models from Experimental Data

    DEFF Research Database (Denmark)

    unknown functionality behind various phenomena in first engineering principles models using experimental data. The proposed modelling approach has significant application potential, e.g. for determining unknown reaction kinetics in both chemical and biological processes. To illustrate the performance......A systematic approach for developing phenomena models from experimental data is presented. The approach is based on integrated application of stochastic differential equation (SDE) modelling and multivariate nonparametric regression, and it is shown how these techniques can be used to uncover...... of the approach, a case study is presented, which shows how an appropriate phenomena model for the growth rate of biomass in a fed-batch bioreactor can be inferred from data....

  2. Nonlinear Photonics and Novel Optical Phenomena

    CERN Document Server

    Morandotti, Roberto


    Nonlinear Photonics and Novel Optical Phenomena contains contributed chapters from leading experts in nonlinear optics and photonics, and provides a comprehensive survey of fundamental concepts as well as hot topics in current research on nonlinear optical waves and related novel phenomena. The book covers self-accelerating airy beams, integrated photonics based on high index doped-silica glass, linear and nonlinear spatial beam dynamics in photonic lattices and waveguide arrays, polariton solitons and localized structures in semiconductor microcavities, terahertz waves, and other novel phenomena in different nanophotonic and optical systems.

  3. Heterogeneity and Microeconometrics Modelling

    DEFF Research Database (Denmark)

    Browning, Martin; Carro, Jesus

    Presented at the 2005 Econometric Society World Congress Plenary Session on "Modelling Heterogeneity". We survey the treatment of heterogeneity in applied microeconometrics analyses. There are three themes. First, there is usually much more heterogeneity than empirical researchers allow for. Second......, the inappropriate treatment of heterogeneity can lead to serious error when estimating outcomes of interest. Finally, once we move away from the traditional linear model with a single 'fixed effect', it is very difficult to account for heterogeneity and fit the data and maintain coherence with theory structures....... The latter task is one for economists: "heterogeneity is too important to be left to the statisticians". The paper concludes with a report of our own research on dynamic discrete choice models that allow for maximal heterogeneity...

  4. Periglacial phenomena affecting nuclear waste disposal

    Directory of Open Access Journals (Sweden)

    Niini, H.


    Full Text Available Slow future changes in astronomic phenomena seem to make it likely that Finland nll suffer several cold periods during the next 100,000 years. The paper analyses the characteristics of the periglacial factors that are most likely to influence the long-term safety of high-level radioactive waste disposed of in bedrock. These factors and their influences have been divided into two categories, natural and human. It is concluded that the basically natural phenomena are theoretically better understood than the complicated phenomena caused by man. It is therefore important in future research into periglacial phenomena, as well as of the disposal problem, to emphasize not only the proper applications of the results of natural sciences, but especially the effects and control of mankind's own present and future activities.

  5. Classifying prion and prion-like phenomena. (United States)

    Harbi, Djamel; Harrison, Paul M


    The universe of prion and prion-like phenomena has expanded significantly in the past several years. Here, we overview the challenges in classifying this data informatically, given that terms such as "prion-like", "prion-related" or "prion-forming" do not have a stable meaning in the scientific literature. We examine the spectrum of proteins that have been described in the literature as forming prions, and discuss how "prion" can have a range of meaning, with a strict definition being for demonstration of infection with in vitro-derived recombinant prions. We suggest that although prion/prion-like phenomena can largely be apportioned into a small number of broad groups dependent on the type of transmissibility evidence for them, as new phenomena are discovered in the coming years, a detailed ontological approach might be necessary that allows for subtle definition of different "flavors" of prion / prion-like phenomena.

  6. High Temperature Phenomena in Shock Waves

    CERN Document Server


    The high temperatures generated in gases by shock waves give rise to physical and chemical phenomena such as molecular vibrational excitation, dissociation, ionization, chemical reactions and inherently related radiation. In continuum regime, these processes start from the wave front, so that generally the gaseous media behind shock waves may be in a thermodynamic and chemical non-equilibrium state. This book presents the state of knowledge of these phenomena. Thus, the thermodynamic properties of high temperature gases, including the plasma state are described, as well as the kinetics of the various chemical phenomena cited above. Numerous results of measurement and computation of vibrational relaxation times, dissociation and reaction rate constants are given, and various ionization and radiative mechanisms and processes are presented. The coupling between these different phenomena is taken into account as well as their interaction with the flow-field. Particular points such as the case of rarefied flows an...

  7. An overview of photocatalysis phenomena applied to NOx abatement. (United States)

    Ângelo, Joana; Andrade, Luísa; Madeira, Luís M; Mendes, Adélio


    This review provides a short introduction to photocatalysis technology in terms of the present environmental remediation paradigm and, in particular, NOx photoabatement. The fundamentals of photoelectrochemical devices and the photocatalysis phenomena are reviewed, highlighting the main reaction mechanisms. The critical historical developments on heterogeneous photocatalysis are briefly discussed, giving particular emphasis to the pioneer works in this field. The third part of this work focus mainly on NOx removal technology considering topics such as: TiO2 photochemistry; effect of the operating conditions on the photocatalysis process; Langmuir-Hinshelwood modeling; TiO2 photocatalytic immobilization approaches; and their applications. The last section of the paper presents the main conclusions and perspectives on the opportunities related to this technology. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Toward a CFD-grade database addressing LWR containment phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Paladino, Domenico, E-mail: [Laboratory for Thermal-Hydraulics, Nuclear Energy and Safety Department, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Andreani, Michele; Zboray, Robert; Dreier, Joerg [Laboratory for Thermal-Hydraulics, Nuclear Energy and Safety Department, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)


    Highlights: Black-Right-Pointing-Pointer The SETH-2 PANDA tests have supplied data with CFD-grade on plumes and jets at large-scale. Black-Right-Pointing-Pointer The PANDA tests have contributed to the understanding of phenomena with high safety relevance for LWRs. Black-Right-Pointing-Pointer The analytical activities related increased confidence in the use of various computational tools for safety analysis. - Abstract: The large-scale, multi-compartment PANDA facility (located at PSI in Switzerland) is one of the state-of-the-art facilities which is continuously upgraded to progressively match the requirements of CFD-grade experiments. Within the OECD/SETH projects, the PANDA facility has been used for the creation of an experimental database on basic containment phenomena e.g. gas mixing, transport, stratification, condensation. In the PANDA tests, these phenomena are driven by large scale plumes or jets. In the paper is presented a selection of the SETH PANDA experimental results. Examples of analytical activities performed at PSI using the GOTHIC, CFX-4 and CFX-5 codes will be used to illustrate how the spatial and temporal resolutions of the measurement grid in PANDA tests are adequate for CFD code (and advanced containment codes) assessment and validation purposes.

  9. Evidence on Dropout Phenomena at Universities

    DEFF Research Database (Denmark)

    Larsen, Malene Rode; Sommersel, Hanna Bjørnøy; Larsen, Michael Søgaard

    This publication is an excerpt from the full technical report ‘Dropout Phenomena at Universities: What is Dropout? Why does Dropout Occur? What Can be Done by the Universities to Prevent or Reduce it? A systematic review’, which was completed in April 2013. The purpose of this excerpt is to present...... the knowledge we have on dropout phenomena at European universities in a short, precise and comprehensible form to allow readers to orient themselves on the subject in a more readable manner....

  10. Surface Chemistry in Heterogeneous Catalysis: An Emerging Discipline. (United States)

    White, J. M.; Campbell, Charles T.


    Provides background data on surface chemistry as an emerging discipline. Highlights the important role which surfaces play in catalysis by focusing on the catalyzed oxidation of carbon monoxide. Provides a demonstration of how surfaces exert their influences in heterogeneous phenomena and illustrates how experimental problems in this field are…

  11. A Heterogeneous Medium Analytical Benchmark

    Energy Technology Data Exchange (ETDEWEB)

    Ganapol, B.D.


    A benchmark, called benchmark BLUE, has been developed for one-group neutral particle (neutron or photon) transport in a one-dimensional sub-critical heterogeneous plane parallel medium with surface illumination. General anisotropic scattering is accommodated through the Green's Function Method (GFM). Numerical Fourier transform inversion is used to generate the required Green's functions which are kernels to coupled integral equations that give the exiting angular fluxes. The interior scalar flux is then obtained through quadrature. A compound iterative procedure for quadrature order and slab surface source convergence provides highly accurate benchmark qualities (4- to 5- places of accuracy) results.

  12. Emergent ultrafast phenomena in correlated oxides and heterostructures (United States)

    Gandolfi, M.; Celardo, G. L.; Borgonovi, F.; Ferrini, G.; Avella, A.; Banfi, F.; Giannetti, C.


    The possibility of investigating the dynamics of solids on timescales faster than the thermalization of the internal degrees of freedom has disclosed novel non-equilibrium phenomena that have no counterpart at equilibrium. Transition metal oxides (TMOs) provide an interesting playground in which the correlations among the charges in the metal d-orbitals give rise to a wealth of intriguing electronic and thermodynamic properties involving the spin, charge, lattice and orbital orders. Furthermore, the physical properties of TMOs can be engineered at the atomic level, thus providing the platform to investigate the transport phenomena on timescales of the order of the intrinsic decoherence time of the charge excitations. Here, we review and discuss three paradigmatic examples of transient emerging properties that are expected to open new fields of research: (i) the creation of non-thermal magnetic states in spin-orbit Mott insulators; (ii) the possible exploitation of quantum paths for the transport and collection of charge excitations in heterostructures; (iii) the transient wave-like behavior of the temperature field in strongly anisotropic TMOs.

  13. First Passage Time for Random Walks in Heterogeneous Networks (United States)

    Hwang, S.; Lee, D.-S.; Kahng, B.


    The first passage time (FPT) for random walks is a key indicator of how fast information diffuses in a given system. Despite the role of FPT as a fundamental feature in transport phenomena, its behavior, particularly in heterogeneous networks, is not yet fully understood. Here, we study, both analytically and numerically, the scaling behavior of the FPT distribution to a given target node, averaged over all starting nodes. We find that random walks arrive quickly at a local hub, and therefore, the FPT distribution shows a crossover with respect to time from fast decay behavior (induced from the attractive effect to the hub) to slow decay behavior (caused by the exploring of the entire system). Moreover, the mean FPT is independent of the degree of the target node in the case of compact exploration. These theoretical results justify the necessity of using a random jump protocol (empirically used in search engines) and provide guidelines for designing an effective network to make information quickly accessible.

  14. [Tumor genetic heterogeneity]. (United States)

    Yang, Yi-Ling; Chu, Jia-You; Wang, Ming-Rong


    Although the majority of spontaneous tumors derive from a single cell, people have come to realize intra-tumor heterogeneity of individual tumors. Human cancers frequently display substantial difference in phenotypic features, such as the degree of differentiation, cell proliferation rate, invasion and metastatic potential, response to therapy and many other aspects. Molecular biology studies have confirmed the occurrence of new mutations during the process of tumor progression, which provide more powerful evidences to show the existence of intra-tumor genetic heterogeneity. This re-view will focus on recent major advances in the study of tumor genetic heterogeneity. Considering that genetic heterogene-ity analysis can provide important information to indicate how long normal cells transform into tumor cells and how to spread and migrate, we firstly describe experimental evidences of intra-tumor genetic heterogeneity. Then we discuss the research value of genetic diversity in the evolutionary history of human individual tumor, introduce the two modes of the genetic heterogeneity - cancer stem cell model and the clonal evolution model, and summarize the implications of in-tra-tumor heterogeneity studies in metastasis and therapy. In addition, the article presents the research methods of genetic heterogeneity, including specific gene and genome-wide level, pointing out their strengths and limitations.

  15. Spooky Phenomena in Two-Photon Processes (United States)

    Li, Ming-Chiang


    A spooky phenomenon in two-photon coherent atomic absorption was discussed in 1980 [M. C. Li, Phys. Rev. A 22 (1980) 1323]. The absorption was initiated by two different laser sources. Classically, it is impossible for atoms to transit coherently in the absorption process, but quantum mechanically it is. This is one of the spooky phenomena in quantum mechanic. Around1990, there were very active experimental pursuits on a spooky phenomenon of two photons emitted from crystal parametric down conversion. The two-photon coherent atomic absorption process contained all basic ingredients as that in crystal parametric down conversion. However, the former arises from two different laser sources. The atom entangles two photons together and becomes a correlatior. The latter arises from a single laser source and two photons are entangled with each other at emission. These two spooky phenomena have been considered as disjointed. The present talk will review two spooky phenomena, and point out their similarities. The investigation on quantum spooky phenomena has led to quantum computing and quantum encryption. It is a hope that the present will stimulate the interest on bring in these two disjointed phenomena together and provide clues in advancing quantum computing and quantum encryption.

  16. Surface fluxes in heterogeneous landscape

    Energy Technology Data Exchange (ETDEWEB)

    Bay Hasager, C.


    The surface fluxes in homogeneous landscapes are calculated by similarity scaling principles. The methodology is well establish. In heterogeneous landscapes with spatial changes in the micro scale range, i e from 100 m to 10 km, advective effects are significant. The present work focus on these effects in an agricultural countryside typical for the midlatitudes. Meteorological and satellite data from a highly heterogeneous landscape in the Rhine Valley, Germany was collected in the large-scale field experiment TRACT (Transport of pollutants over complex terrain) in 1992. Classified satellite images, Landsat TM and ERS SAR, are used as basis for roughness maps. The roughnesses were measured at meteorological masts in the various cover classes and assigned pixel by pixel to the images. The roughness maps are aggregated, i e spatially averaged, into so-called effective roughness lengths. This calculation is performed by a micro scale aggregation model. The model solves the linearized atmospheric flow equations by a numerical (Fast Fourier Transform) method. This model also calculate maps of friction velocity and momentum flux pixel wise in heterogeneous landscapes. It is indicated how the aggregation methodology can be used to calculate the heat fluxes based on the relevant satellite data i e temperature and soil moisture information. (au) 10 tabs., 49 ills., 223 refs.

  17. Heterogeneity in magnetic complex oxides (United States)

    Arenholz, Elke

    Heterogeneity of quantum materials on the nanoscale can result from the spontaneous formation of regions with distinct atomic, electronic and/or magnetic order, and indicates coexistence of competing quantum phases. In complex oxides, the subtle interplay of lattice, charge, orbital, and spin degrees of freedom gives rise to especially rich phase diagrams. For example, coexisting conducting and insulating phases can occur near metal-insulator transitions, colossal magnetoresistance can emerge where ferromagnetic and antiferromagnetic domains compete, and charge-ordered and superconducting regions are present simultaneously in materials exhibiting high-temperature superconductivity. Additionally, externally applied fields (electric, magnetic, or strain) or other external excitations (light or heat) can tip the energy balance towards one phase, or support heterogeneity and phase coexistence and provide the means to perturb and tailor quantum heterogeneity at the nanoscale. Engineering nanomaterials, with structural, electronic and magnetic characteristics beyond what is found in bulk materials, is possible today through the technique of thin film epitaxy, effectively a method of `spray painting' atoms on single crystalline substrates to create precisely customized layered structures with atomic arrangements defined by the underlying substrate. Charge transfer and spin polarization across interfaces as well as imprinting nanoscale heterogeneity between adjacent layers lead to intriguing and important new phenomena testing our understanding of basic physics and creating new functionalities. Moreover, the abrupt change of orientation of an order parameter between nanoscale domains can lead to unique phases that are localized at domain walls, including conducting domain walls in insulating ferroelectrics, and ferromagnetic domain walls in antiferromagnets. Here we present our recent results on tailoring the electronic anisotropy of multiferroic heterostructures by

  18. Theories of dynamical phenomena in sunspots (United States)

    Thomas, J. H.

    Attempts that have been made to understand and explain observed dynamical phenomena in sunspots within the framework of magnetohydrodynamic theory are surveyed. The qualitative aspects of the theory and physical arguments are emphasized, with mathematical details generally avoided. The dynamical phenomena in sunspots are divided into two categories: aperiodic (quasi-steady) and oscillatory. For each phenomenon discussed, the salient observational features that any theory should explain are summarized. The two contending theoretical models that can account for the fine structure of the Evershed motion, namely the convective roll model and the siphon flow model, are described. With regard to oscillatory phenomena, attention is given to overstability and oscillatory convection, umbral oscillations and flashes. penumbral waves, five-minute oscillations in sunspots, and the wave cooling of sunspots.

  19. The making of extraordinary psychological phenomena. (United States)

    Lamont, Peter


    This article considers the extraordinary phenomena that have been central to unorthodox areas of psychological knowledge. It shows how even the agreed facts relating to mesmerism, spiritualism, psychical research, and parapsychology have been framed as evidence both for and against the reality of the phenomena. It argues that these disputes can be seen as a means through which beliefs have been formulated and maintained in the face of potentially challenging evidence. It also shows how these disputes appealed to different forms of expertise, and that both sides appealed to belief in various ways as part of the ongoing dispute about both the facts and expertise. Finally, it shows how, when a formal Psychology of paranormal belief emerged in the twentieth century, it took two different forms, each reflecting one side of the ongoing dispute about the reality of the phenomena. © 2012 Wiley Periodicals, Inc.

  20. Nonlinear phenomena in contemporary vocal music. (United States)

    Neubauer, Jürgen; Edgerton, Michael; Herzel, Hanspeter


    Complex and multiphonic voice signals of vocal improvisors are analyzed within the framework of nonlinear dynamics. Evidence is given that nonlinear phenomena are extensively used by performers associated with contemporary music. Narrow-band spectrograms of complex vocalizations are used to visualize the appearance of nonlinear phenomena (spectral bifurcation diagrams). Possible production mechanisms are discussed in connection with previous research, personal performance and pedagogical experience. Examples for period doubling, biphonation and irregular aperiodic phonation in vocal sonorities of contemporary vocal improvisors are given, and glottal whistle production encompassed with biphonation and triphonation is shown. Furthermore, coincidences of harmonics-formant matching associated with abrupt transitions to subharmonics and biphonation in the vocal output are provided. This also shows the recurrent use of nonlinear phenomena by performers. It is argued that mechanisms such as source-tract coupling or vocal fold desynchronization due to asymmetry are used in a reproducible way for musical tasks.

  1. Stability and Restoration phenomena in Competitive Systems

    CERN Document Server

    Uechi, Lisa


    A conservation law and stability, recovering phenomena and characteristic patterns of a nonlinear dynamical system have been studied and applied to biological and ecological systems. In our previous study, we proposed a system of symmetric 2n-dimensional conserved nonlinear differential equations with external perturbations. In this paper, competitive systems described by 2-dimensional nonlinear dynamical (ND) model with external perturbations are applied to population cycles and recovering phenomena of systems from microbes to mammals. The famous 10-year cycle of population density of Canadian lynx and snowshoe hare is numerically analyzed. We find that a nonlinear dynamical system with a conservation law is stable and generates a characteristic rhythm (cycle) of population density, which we call the {\\it standard rhythm} of a nonlinear dynamical system. The stability and restoration phenomena are strongly related to a conservation law and balance of a system. The {\\it standard rhythm} of population density ...

  2. Current-driven phenomena in nanoelectronics

    CERN Document Server

    Seideman, Tamar


    Consisting of ten chapters written by some of the world's leaders in the field, this book combines experimental, theoretical and numerical studies of current-driven phenomena in the nanoscale. The topics covered range from single-molecule, site-specific nanochemistry induced by a scanning tunneling microscope, through inelastic tunneling spectroscopy and current-induced heating, to current-triggered molecular machines. The various chapters focus on experimental and numerical method development, the description of specific systems, and new ideas and novel phenomena.

  3. Dissipative phenomena in condensed matter some applications

    CERN Document Server

    Dattagupta, Sushanta


    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.

  4. Dynamics in population heterogeneity during batch and continuous fermentation of Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Heins, Anna-Lena; Lencastre Fernandes, Rita; Lundin, L.


    environmental changes, which might pose stress on the cells, affect their metabolism and consequently influence the level of heterogeneity of the population. To gain a deeper understanding of population heterogeneity and the triggering phenomena, a Saccharomyces cerevisiae growth reporter strain based...... distribution during different growth stages. To further simulate which effect gradients have on population heterogeneity, glucose and ethanol perturbations during continuous cultivation were performed. Physiological changes were analyzed on single cell level by using flow cytometry followed by cell sorting...

  5. Exploring tumor heterogeneity

    NARCIS (Netherlands)

    Fessler, E.


    Cancer is a heterogeneous disease, which is reflected both on the cellular and the population level. Advances in detection, diagnosis, and treatment of malignancies have increased survival time of cancer patients; yet, the heterogeneity observed within and between tumors complicates accurate

  6. Pore-network model of evaporation-induced salt precipitation in porous media: The effect of correlations and heterogeneity (United States)

    Dashtian, Hassan; Shokri, Nima; Sahimi, Muhammad


    Salt transport and precipitation in porous media constitute a set of complex and fascinating phenomena that are of considerable interest to several important problems, ranging from storage of CO2 in geological formations, to soil fertility, and protection of pavements and roads, as well as historical monuments. The phenomena occur at the pore scale and are greatly influenced by the heterogeneity of the pore space morphology. We present a pore-network (PN) model to study the phenomena. Vapor diffusion, capillary effect at the brine-vapor interface, flow of brine, and transport of salt and its precipitation in the pores that plug the pores partially or completely are all accounted for. The drying process is modeled by the invasion percolation, while transport of salt in brine is accounted for by the convective-diffusion equation. We demonstrate that the drying patterns, the clustering and connectivity of the pore throats in which salt precipitation occurs, the saturation distribution, and the drying rate are all strongly dependent upon the pore-size distribution, the correlations among the pore sizes, and the anisotropy of the pore space caused by stratification that most natural porous media contain. In particular, if the strata are more or less parallel to the direction of injection of the gas that dries out the pore space (air, for example) and/or causes salt precipitation (CO2, for example), the drying rate increases significantly. Moreover, salt tends to precipitate in clusters of neighboring pores that are parallel to the open surface of the porous medium.

  7. Fluid mechanics phenomena in microgravity; ASME Winter Annual Meeting, Anaheim, CA, Nov. 8-13, 1992 (United States)

    Siginer, Dennis A. (Editor); Weislogel, Mark M. (Editor)


    This paper is the first in a series of symposia presenting research activity in microgravity fluid mechanics. General topics addressed include two-phase flow and transport phenomena, thermo-capillary flow, and interfacial stability. Papers present mathmatical models of fluid dynamics in the microgravity environment. Applications suggested include space manufacturing and storage of liquids in low gravity.

  8. Temporal Phenomena in the Korean Conjunctive Constructions (United States)

    Kim, Dongmin


    The goal of this study is to characterize the temporal phenomena in the Korean conjunctive constructions. These constructions consist of three components: a verbal stem, a clause medial temporal suffix, and a clause terminal suffix. This study focuses on both the temporality of the terminal connective suffixes and the grammatical meanings of the…

  9. Black hole critical phenomena without black holes

    Indian Academy of Sciences (India)

    Abstract. Studying the threshold of black hole formation via numerical evolution has led to the discovery of fascinating nonlinear phenomena. Power-law mass scaling, aspects of universality, and self-similarity have now been found for a large variety of models. However, questions remain. Here I briefly review critical ...

  10. Modelling of flow phenomena during DC casting

    NARCIS (Netherlands)

    Zuidema, J.


    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

  11. Simple classical approach to spin resonance phenomena

    DEFF Research Database (Denmark)

    Gordon, R A


    A simple classical method of describing spin resonance in terms of the average power absorbed by a spin system is discussed. The method has several advantages over more conventional treatments, and a number of important spin resonance phenomena, not normally considered at the introductory level...

  12. Quantum phenomena in magnetic nano clusters

    Indian Academy of Sciences (India)


    Quantum phenomena in magnetic nano clusters. 461. Figure 3. Schematic exchange interactions in a V15 cluster. There is no direct exchange interaction amongst the triangle spins. Interactions not shown explicitly can be generated from the C3 symmetry of the system. simplify the calculations, the strongly coupled ...

  13. Quantum phenomena in magnetic nano clusters

    Indian Academy of Sciences (India)

    While semiconductor structures have provided paradigms of nanosystems from the stand point of electronic phenomena, the synthesis of high nuclearity transition metal complexes have provided examples of nano magnets. The range and diversity of the properties exhibited by these systems rivals its electronic counterparts ...

  14. Hyperchaotic phenomena in dynamic decision making

    DEFF Research Database (Denmark)

    Thomsen, Jesper Skovhus; Mosekilde, Erik; Sterman, John David


    of this article is to show how the decision making behavior of real people in simulated corporate environments can lead to chaotic, hyperchaotic and higher-order hyperchaotic phenomena. Characteristics features of these complicated forms of behavior are analyzed with particular emphasis on an interesting form...

  15. Novel experimentally observed phenomena in soft matter

    Indian Academy of Sciences (India)

    Experiments that report a spectrum of novel phenomena exhibited by these materials, such as turbulent drag reduction, elastic turbulence, the formation of shear bands and the existence of rheological chaos, flow-induced birefringence and the unusual rheology of soft glassy materials, are reviewed. The focus then shifts to ...

  16. Reflection equations and surface critical phenomena


    Batchelor, M. T.


    A brief review is given of recent developments in the study of surface critical phenomena from the viewpoint of exactly solved lattice models. These developments include exact results for the polymer adsorption transition and the surface critical exponents of the eight-vertex model.

  17. Some Phenomena on Negative Inversion Constructions (United States)

    Sung, Tae-Soo


    We examine the characteristics of NDI (negative degree inversion) and its relation with other inversion phenomena such as SVI (subject-verb inversion) and SAI (subject-auxiliary inversion). The negative element in the NDI construction may be" not," a negative adverbial, or a negative verb. In this respect, NDI has similar licensing…

  18. Fourier Series The Mathematics of Periodic Phenomena

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 1; Issue 10. Fourier Series The Mathematics of Periodic Phenomena. S Thangavelu ... Author Affiliations. S Thangavelu1. Department of Mathematics and Statistics, University of New Mexico, Humanities Building 419, Albuquerque, NM 87131-1141, USA ...

  19. Coherent topological phenomena in protein folding

    DEFF Research Database (Denmark)

    Bohr, Henrik; Brunak, Søren; Bohr, Jakob


    A theory is presented for coherent topological phenomena in protein dynamics with implications for protein folding and stability. We discuss the relationship to the writhing number used in knot diagrams of DNA. The winding state defines a long-range order along the backbone of a protein with long...

  20. Intervention in Biological Phenomena via Feedback Linearization. (United States)

    Fnaiech, Mohamed Amine; Nounou, Hazem; Nounou, Mohamed; Datta, Aniruddha


    The problems of modeling and intervention of biological phenomena have captured the interest of many researchers in the past few decades. The aim of the therapeutic intervention strategies is to move an undesirable state of a diseased network towards a more desirable one. Such an objective can be achieved by the application of drugs to act on some genes/metabolites that experience the undesirable behavior. For the purpose of design and analysis of intervention strategies, mathematical models that can capture the complex dynamics of the biological systems are needed. S-systems, which offer a good compromise between accuracy and mathematical flexibility, are a promising framework for modeling the dynamical behavior of biological phenomena. Due to the complex nonlinear dynamics of the biological phenomena represented by S-systems, nonlinear intervention schemes are needed to cope with the complexity of the nonlinear S-system models. Here, we present an intervention technique based on feedback linearization for biological phenomena modeled by S-systems. This technique is based on perfect knowledge of the S-system model. The proposed intervention technique is applied to the glycolytic-glycogenolytic pathway, and simulation results presented demonstrate the effectiveness of the proposed technique.

  1. Intervention in Biological Phenomena via Feedback Linearization

    Directory of Open Access Journals (Sweden)

    Mohamed Amine Fnaiech


    Full Text Available The problems of modeling and intervention of biological phenomena have captured the interest of many researchers in the past few decades. The aim of the therapeutic intervention strategies is to move an undesirable state of a diseased network towards a more desirable one. Such an objective can be achieved by the application of drugs to act on some genes/metabolites that experience the undesirable behavior. For the purpose of design and analysis of intervention strategies, mathematical models that can capture the complex dynamics of the biological systems are needed. S-systems, which offer a good compromise between accuracy and mathematical flexibility, are a promising framework for modeling the dynamical behavior of biological phenomena. Due to the complex nonlinear dynamics of the biological phenomena represented by S-systems, nonlinear intervention schemes are needed to cope with the complexity of the nonlinear S-system models. Here, we present an intervention technique based on feedback linearization for biological phenomena modeled by S-systems. This technique is based on perfect knowledge of the S-system model. The proposed intervention technique is applied to the glycolytic-glycogenolytic pathway, and simulation results presented demonstrate the effectiveness of the proposed technique.

  2. Hopping transport in solids

    CERN Document Server

    Pollak, M


    The hopping process, which differs substantially from conventional transport processes in crystals, is the central process in the transport phenomena discussed in this book. Throughout the book the term ``hopping'' is defined as the inelastic tunneling transfer of an electron between two localized electronic states centered at different locations. Such processes do not occur in conventional electronic transport in solids, since localized states are not compatible with the translational symmetry of crystals.The rapid growth of interest in hopping transport has followed in the footsteps of the

  3. Methods to optimize livestock breeding programs with genotype by environment interaction and genetic heterogeneity of environmental variance

    NARCIS (Netherlands)

    Mulder, H.A.


    Genotype by environment interaction (G × E) and genetic heterogeneity of environmental variance are both related to genetic variation in environmental sensitivity. Both phenomena can have consequences for livestock breeding programs. This thesis focuses on developing methods to optimize livestock

  4. The Numerical Nuclear Reactor for High-Fidelity Integrated Simulation of Neutronic, Thermal-Hydraulic, and Thermo-Mechanical Phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K. S.; Ju, H. G.; Jeon, T. H. and others


    A comprehensive high fidelity reactor core modeling capability has been developed for detailed analysis of current and advanced reactor designs as part of a US-ROK collaborative I-NERI project. High fidelity was accomplished by integrating highly refined solution modules for the coupled neutronic, thermal-hydraulic, and thermo-mechanical phenomena. Each solution module employs methods and models that are formulated faithfully to the first-principles governing the physics, real geometry, and constituents. Specifically, the critical analysis elements that are incorporated in the coupled code capability are whole-core neutron transport solution, ultra-fine-mesh computational fluid dynamics/heat transfer solution, and finite-element-based thermo-mechanics solution, all obtained with explicit (fuel pin cell level) heterogeneous representations of the components of the core. The vast computational problem resulting from such highly refined modeling is solved on massively parallel computers, and serves as the 'numerical nuclear reactor'. Relaxation of modeling parameters were also pursued to make problems run on clusters of workstations and PCs for smaller scale applications as well.

  5. Heterogeneous cellular networks

    CERN Document Server

    Hu, Rose Qingyang


    A timely publication providing coverage of radio resource management, mobility management and standardization in heterogeneous cellular networks The topic of heterogeneous cellular networks has gained momentum in industry and the research community, attracting the attention of standardization bodies such as 3GPP LTE and IEEE 802.16j, whose objectives are looking into increasing the capacity and coverage of the cellular networks. This book focuses on recent progresses,  covering the related topics including scenarios of heterogeneous network deployment, interference management i

  6. Heterogeneity and Scaling in Geologic Media

    Energy Technology Data Exchange (ETDEWEB)

    Gregory N. Boitnott; Gilles Y. Bussod; Paul N. Hagin; Stephen R. Brown


    The accurate characterization and remediation of contaminated subsurface environments requires the detailed knowledge of subsurface structures and flow paths. Enormous resources are invested in scoping and characterizing sites using core sampling, 3-D geophysical surveys, well tests, etc.... Unfortunately, much of the information acquired is lost to compromises and simplifications made in constructing numerical grids for the simulators used to predict flow and transport from the contaminated area to the accessible environment. In rocks and soils, the bulk geophysical and transport properties of the matrix and of fracture systems are determined by the juxtaposition of geometric features at many length scales. In the interest of computational efficiency, recognized heterogeneities are simplified, averaged out, or entirely ignored in spite of recent studies that recognize that: (1) Structural and lithologic heterogeneities exist on all scales in rocks. (2) Small heterogeneities influence, and can control the physical and chemical properties of rocks. In this work we propose a physically based approach for the description and treatment of heterogeneities, that highlights the use of laboratory equipment designed to measure the effect on physical properties of fine scale heterogeneities observed in rocks and soils. We then discuss the development of an integration methodology that uses these measurements to develop and upscale flow and transport models. Predictive simulations are 'calibrated' to the measured heterogeneity data, and subsequently upscaled in a way that is consistent with the transport physics and the efficient use of environmental geophysics. This methodology provides a more accurate interpretation and representation of the subsurface for both environmental engineering and remediation. We show through examples, (i) the important influence of even subtle heterogeneity in the interpreting of geophysical data, and (ii) how physically based upscaling

  7. Quantum chemistry and charge transport in biomolecules with superconducting circuits

    National Research Council Canada - National Science Library

    García-Álvarez, L; Las Heras, U; Mezzacapo, A; Sanz, M; Solano, E; Lamata, L


    We propose an efficient protocol for digital quantum simulation of quantum chemistry problems and enhanced digital-analog quantum simulation of transport phenomena in biomolecules with superconducting circuits...

  8. Impact of measurable physical phenomena on contact thermal comfort

    Directory of Open Access Journals (Sweden)

    Fojtlín Miloš


    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.

  9. Impact of measurable physical phenomena on contact thermal comfort (United States)

    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.

  10. Improved Heterogeneous Distance Functions


    Wilson, D. R.; Martinez, T. R.


    Instance-based learning techniques typically handle continuous and linear input values well, but often do not handle nominal input attributes appropriately. The Value Difference Metric (VDM) was designed to find reasonable distance values between nominal attribute values, but it largely ignores continuous attributes, requiring discretization to map continuous values into nominal values. This paper proposes three new heterogeneous distance functions, called the Heterogeneous Value Difference M...

  11. Magnetotransport phenomena in layered conductors under magnetic breakdown (United States)

    Galbova, O.; Peschansky, V. G.; Stepanenko, D. I.


    We study the transport phenomena in layered conductors with rather general electron energy spectrum placed in a high magnetic field H, under conditions when the distance between various sheets of the Fermi surface (FS) may become small under the external effects, such as hydrostatic pressure or impurity atom doping, and electrons can transfer from one sheet of the FS to another due to magnetic breakdown. We calculate the dependence of the in-plane electrical conductivity and magnetoresistance on magnetic field and probability of magnetic breakdown and show that the field-induced quadratic increase of the in-plane resistance in the absence of magnetic breakdown is changed by a linear dependence on H. With a further reduction of the energy gap between FS sheets, the in-plane resistance is saturated.

  12. Some optical and dynamical phenomena in the Rindler model

    CERN Document Server

    Birsin, E


    In Rindler's model of a uniformly accelerated reference frame we analyze the apparent shape of rods and marked light rays for the case that the observers as well as the rods and the sources of light are at rest with respect to the Rindler observers. Contrary to the expectation suggested by the strong principle of equivalence, there is no apparent "bending down" of a light ray with direction transversal to the direction of acceleration, but a straight rod oriented orthogonal to the direction of acceleration appears bended "upwards". These optical phenomena are in accordance with the dynamical experience of observers guided by a straight track or a track curved in the same way as the marked light ray, respectively: While the former observer feels a centrifugal force directed "downwards", the centrifugal force for the latter vanishes. The properties of gyroscope transport along such tracks are correspondingly.

  13. Tunable caustic phenomena in electron wavefields

    Energy Technology Data Exchange (ETDEWEB)

    Tavabi, Amir Hossein, E-mail: [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) and Peter Grünberg Institute (PGI), Forschungszentrum Jülich, D-52425 Jülich (Germany); Migunov, Vadim; Dwyer, Christian; Dunin-Borkowski, Rafal E. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) and Peter Grünberg Institute (PGI), Forschungszentrum Jülich, D-52425 Jülich (Germany); Pozzi, Giulio [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) and Peter Grünberg Institute (PGI), Forschungszentrum Jülich, D-52425 Jülich (Germany); Department of Physics and Astronomy, University of Bologna, Viale B. Pichat 6/2, 40127 Bologna (Italy)


    Novel caustic phenomena, which contain fold, butterfly and elliptic umbilic catastrophes, are observed in defocused images of two approximately collinear oppositely biased metallic tips in a transmission electron microscope. The observed patterns depend sensitively on defocus, on the applied voltage between the tips and on their separation and lateral offset. Their main features are interpreted on the basis of a projected electrostatic potential model for the electron-optical phase shift. - Highlights: • Electron-optical caustics are observed in defocused images of biased metallic tips. • The caustics depend on defocus, on the bias between the tips and on their separation. • The setup offers the flexibility to study a wide variety of caustic phenomena.

  14. Ordering phenomena in ABA triblock copolymer gels

    DEFF Research Database (Denmark)

    Reynders, K.; Mischenko, N.; Kleppinger, R.


    Temperature and concentration dependencies of the degree of order in ABA triblock copolymer gels are discussed. Two factors can influence the ordering phenomena: the conformation of the midblocks (links of the network) and the polydispersity of the endblock domains (nodes of the network). The lat......Temperature and concentration dependencies of the degree of order in ABA triblock copolymer gels are discussed. Two factors can influence the ordering phenomena: the conformation of the midblocks (links of the network) and the polydispersity of the endblock domains (nodes of the network...... crystalline lattice with close-packed spheres or with cubic (presumably BCC) equilibrium morphology. The appearance of the latter is never detected in the gels with a stretched conformation of the midblock....

  15. Natural phenomena hazards site characterization criteria

    Energy Technology Data Exchange (ETDEWEB)


    The criteria and recommendations in this standard shall apply to site characterization for the purpose of mitigating Natural Phenomena Hazards (wind, floods, landslide, earthquake, volcano, etc.) in all DOE facilities covered by DOE Order 5480.28. Criteria for site characterization not related to NPH are not included unless necessary for clarification. General and detailed site characterization requirements are provided in areas of meteorology, hydrology, geology, seismology, and geotechnical studies.

  16. Workshop on Nonlinear Phenomena in Complex Systems

    CERN Document Server


    This book contains a thorough treatment of neural networks, cellular-automata and synergetics, in an attempt to provide three different approaches to nonlinear phenomena in complex systems. These topics are of major interest to physicists active in the fields of statistical mechanics and dynamical systems. They have been developed with a high degree of sophistication and include the refinements necessary to work with the complexity of real systems as well as the more recent research developments in these areas.

  17. AC Electrokinetic Phenomena Generated by Microelectrode Structures (United States)

    Hart, Robert; Oh, Jonghyun; Capurro, Jorge; Noh, Hongseok (Moses)


    The field of AC electrokinetics is rapidly growing due to its ability to perform dynamic fluid and particle manipulation on the micro- and nano-scale, which is essential for Lab-on-a-Chip applications. AC electrokinetic phenomena use electric fields to generate forces that act on fluids or suspended particles (including those made of dielectric or biological material) and cause them to move in astonishing ways1, 2. Within a single channel, AC electrokinetics can accomplish many essential on-chip operations such as active micro-mixing, particle separation, particle positioning and micro-pattering. A single device may accomplish several of those operations by simply adjusting operating parameters such as frequency or amplitude of the applied voltage. Suitable electric fields can be readily created by micro-electrodes integrated into microchannels. It is clear from the tremendous growth in this field that AC electrokinetics will likely have a profound effect on healthcare diagnostics3-5, environmental monitoring6 and homeland security7. In general, there are three AC Electrokinetic phenomena (AC electroosmosis, dielectrophoresis and AC electrothermal effect) each with unique dependencies on the operating parameters. A change in these operating parameters can cause one phenomena to become dominant over another, thus changing the particle or fluid behavior. It is difficult to predict the behavior of particles and fluids due to the complicated physics that underlie AC electrokinetics. It is the goal of this publication to explain the physics and elucidate particle and fluid behavior. Our analysis also covers how to fabricate the electrode structures that generate them, and how to interpret a wide number of experimental observations using several popular device designs. This video article will help scientists and engineers understand these phenomena and may encourage them to start using AC Electrokinetics in their research. PMID:19066515

  18. Bridge windshield design to avoid aeroelastic phenomena


    Ogueta Gutiérrez, Mikel; Franchini Longhi, Sebastian Nicolas


    Since in 1940 the Tacoma Narrows Bridge was destroyed by the wind, aeroelastic instabilities have been recognized as one of the most challenging aspects of bridge design. They can produce long-term fatigue failure through vortex induced vibrations, or sudden collapse through self-excited flutter. These vibrations may also cause discomfort for the users and temporary closure of the bridge. Wind tunnel studies are a very helpful tool to understand these phenomena. By means of them, the critical...

  19. Corporate Strategy And The Social Networking Phenomena


    Johnson, Robert L.


    The Social Networking (SN) phenomena has developed relatively overnight and is continuing to develop at an exponential pace. It allows for innovative new methods of disseminating and collecting information in ways never before dreamed possible by corporate executives. The rise of Social Networking is becoming a disruptive technology for traditional marketing and advertising medium such as radio, television, web page, and print media, creating new business opportunities for the entrepreneur w...

  20. Duality in Liouville theory and moonshine phenomena


    Eguchi, Tohru; Sugawara, Yuji


    We consider the Liouville theory by varying the linear dilaton coupling constant . It is known that, at two different values of coupling constant , the system exhibits two different small superconformal symmetries with central charge and , respectively. In the context of string theory these two theories are considered to describe the Coulomb and Higgs branches of the theory and are expected to be dual to each other. We study the Mathieu and umbral moonshine phenomena in these two theories and...

  1. Bion and Tustin: the autistic phenomena. (United States)

    Korbivcher, Celia Fix


    This article examines the implications of the proposal of autistic transformations within the general context of Bion's theory of Transformations. The aim is to confirm the coherence of this proposal of autistic transformations within the overall structure of Bion's theory of Transformations. She examines the relation between emotional links and their negatives, particularly -K. She questions in which of the dimensions of the mind the autistic phenomena are located, the relation between autistic phenomena and beta elements, and where to place them in the Grid. The author tries to form metapsychological support for the incorporation of the autistic area in Bion's theory of Transformations. She argues that, despite the incongruence and imprecision of this incorporation, such autistic phenomena cannot be excluded from the complexus of the human mind and should therefore be accounted for in Bion's transformations. She discusses the idea that the theory of transformations includes the field of the neurosis and psychosis and deals with emotions, whereas the autistic area is dominated by sensations. The author asks how to add the autistic area to Bion's theory. Clinical material of a child for whom the non-psychotic part of the personality predominates and who presents autistic nuclei provides material for the discussion. Copyright © 2013 Institute of Psychoanalysis.

  2. Quantum Chess: Making Quantum Phenomena Accessible (United States)

    Cantwell, Christopher

    Quantum phenomena have remained largely inaccessible to the general public. There tends to be a scare factor associated with the word ``Quantum''. This is in large part due to the alien nature of phenomena such as superposition and entanglement. However, Quantum Computing is a very active area of research and one day we will have games that run on those quantum computers. Quantum phenomena such as superposition and entanglement will seem as normal as gravity. Is it possible to create such games today? Can we make games that are built on top of a realistic quantum simulation and introduce players of any background to quantum concepts in a fun and mentally stimulating way? One of the difficulties with any quantum simulation run on a classical computer is that the Hilbert space grows exponentially, making simulations of an appreciable size physically impossible due largely to memory restrictions. Here we will discuss the conception and development of Quantum Chess, and how to overcome some of the difficulties faced. We can then ask the question, ``What's next?'' What are some of the difficulties Quantum Chess still faces, and what is the future of quantum games?

  3. Microbial population heterogeneity versus bioreactor heterogeneity: evaluation of Redox Sensor Green as an exogenous metabolic biosensor

    DEFF Research Database (Denmark)

    Baert, Jonathan; Delepierre, Anissa; Telek, Samuel


    performances (i.e. microbial population heterogeneity). In this work, we have evaluated the relevance of Redox Sensor Green (RSG) as an exogenous biosensor of metabolic activity at the single cell level. RSG signal is proportional to the activity of the electron transport chain and its signal is strongly...

  4. Local probe investigation of emergent phenomena in complex oxide heterointerfaces (United States)

    Huang, Mengchen

    Complex oxide heterointerfaces exhibit rich physics as well as many veiled puzzles. LaAlO3/SrTiO3 (LAO/STO) is one of the prototype of such heterointerfaces. In 2004, Ohtomo and Hwang first reported a conducing interface emerged between perovskite oxide insulators LaAlO3 and SrTiO3. Following this seminal discovery, many emergent phenomena like metal-insulator transition, piezoresponse, superconductivity, magnetism, strong spin-orbit coupling and coexistence of superconductivity and magnetism were reported in the fascinating LAO/STO system. However, the origin of the conducting interface is still the subject of intense debate, and the physics behind these emergent phenomena remains a wild space to be explored. My Ph.D. study focused on the emergent phenomena in LAO/STO by using "local probes" -- nanostructures created by conductive atomic force microscope (c-AFM) lithography and the AFM itself. I used piezoresponse force microscope (PFM) to study the electromechanical response in LAO/STO and developed a high-resolution, non-destructive PFM imaging technique to visualize nanostructures at LAO/STO interface. The results indicate that the PFM signal is related to a carrier density mediated interfacial lattice distortion, and surface adsorbates can affect the PFM signal via coupling to the electrons at the interface. I integrated graphene on LAO/STO, created field-effect devices in graphene/LAO/STO and collaborated with Dr. Giriraj Jnawali to investigate the transport properties. The high quality single layer graphene on LAO/STO exhibited the half-integer quantum Hall effect and room temperature weak antilocalization behavior. I performed transport measurements in (110)-oriented LAO/STO to investigate anisotropic quasi one-dimensional superconductivity in nanowires. Based on the results I proposed a plausible explanation related to the Lifshitz transition and anisotropic band structures of nanowires in (110)-oriented LAO/STO. Co-worked with Dr. Keith Brown, I studied

  5. DOE Energy Frontiers Research Center for Heterogeneous Functional Materials; the “HeteroFoaM Center”

    Energy Technology Data Exchange (ETDEWEB)

    Reifsnider, Kenneth Leonard [Univ. of South Carolina, Columbia, SC (United States)


    transformation and storage. The scope of the HeteroFoaM center was focused on the discovery and development of the control science of key phenomena across multiple length scales that create functionality in heterogeneous materials and their structured interfaces, boundaries, and surfaces for applications in energy technologies. The HeteroFoaM Center defined a critical path and established an essential foundation for progress in the field of heterogeneous functional materials. Perhaps the single most important element of progress was the establishment of the capability to design, characterize, and model heterogeneous functional materials at the conformal level, i.e., for a limited set of material systems, the HeteroFoaM team defined how to control the order / disorder at the atomic level, the surfaces, and the interfaces for selected constituent morphologies, and to use multiphysical models to explain the remarkable property variations resulting from that control science for several heterogeneous material systems. For those cases we defined “meso-structures” (at various scales) where the interactive physics of constituent phases acted to create emergent properties, e.g., strongly emergent mixed conductor behavior and ionic transport. The general approach used by this EFRC is shown in Fig. 1. The HeteroFoaM Center created the genre of Heterogeneous Functional Materials with functional surfaces and interfaces (including void phases) called HeteroFoaM as a science platform to enable rational analysis and design of functional material systems by focusing on the meso-interactions that drive emergent response. The team firmly established this approach with over 180 archival publications (see “Publications” section), 7 patent applications, and over 100 invited lectures in 15 countries on this topic, enabled by building a remarkably effective and uniquely coherent research team. Indeed, our team was our principal strength; this problem eluded solution earlier because such a team

  6. A Chaotic-Dynamical Conceptual Model to Describe Fluid flow and Contaminant Transport in a Fractured Vadose zone

    Energy Technology Data Exchange (ETDEWEB)

    Faybishenko, Boris; Doughty, Christine; Stoops, Thomas M.; Wood, thomas R.; Wheatcraft, Stephen W.


    (1) To determine if and when dynamical chaos theory can be used to investigate infiltration of fluid and contaminant transport in heterogeneous soils and fractured rocks. (2) To introduce a new approach to the multiscale characterization of flow and transport in fractured basalt vadose zones and to develop physically based conceptual models on a hierarchy of scales. The following activities are indicative of the success in meeting the project s objectives: A series of ponded infiltration tests, including (1) small-scale infiltration tests (ponded area 0.5 m2) conducted at the Hell s Half Acre site near Shelley, Idaho, and (2) intermediate-scale infiltration tests (ponded area 56 m2) conducted at the Box Canyon site near Arco, Idaho. Laboratory investigations and modeling of flow in a fractured basalt core. A series of small-scale dripping experiments in fracture models. Evaluation of chaotic behavior of flow in laboratory and field experiments using methods from nonlinear dynamics; Evaluation of the impact these dynamics may have on contaminant transport through heterogeneous fractured rocks and soils, and how it can be used to guide remediation efforts; Development of a conceptual model and mathematical and numerical algorithms for flow and transport that incorporate (1) the spatial variability of heterogeneous porous and fractured media, and (2) the description of the temporal dynamics of flow and transport, both of which may be chaotic. Development of appropriate experimental field and laboratory techniques needed to detect diagnostic parameters for chaotic behavior of flow. This approach is based on the assumption that spatial heterogeneity and flow phenomena are affected by nonlinear dynamics, and in particular, by chaotic processes. The scientific and practical value of this approach is that we can predict the range within which the parameters of flow and transport change with time in order to design and manage the remediation, even when we can not predict

  7. Green heterogeneous wireless networks

    CERN Document Server

    Ismail, Muhammad; Nee, Hans-Peter; Qaraqe, Khalid A; Serpedin, Erchin


    This book focuses on the emerging research topic "green (energy efficient) wireless networks" which has drawn huge attention recently from both academia and industry. This topic is highly motivated due to important environmental, financial, and quality-of-experience (QoE) considerations. Specifically, the high energy consumption of the wireless networks manifests in approximately 2% of all CO2 emissions worldwide. This book presents the authors’ visions and solutions for deployment of energy efficient (green) heterogeneous wireless communication networks. The book consists of three major parts. The first part provides an introduction to the "green networks" concept, the second part targets the green multi-homing resource allocation problem, and the third chapter presents a novel deployment of device-to-device (D2D) communications and its successful integration in Heterogeneous Networks (HetNets). The book is novel in that it specifically targets green networking in a heterogeneous wireless medium, which re...

  8. Studies of Novel Quantum Phenomena in Ruthenates

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Zhiqiang


    Strongly correlated oxides have been the subject of intense study in contemporary condensed matter physics, and perovskite ruthenates (Sr,Ca)n+1RunO3n+1 have become a new focus in this field. One of important characteristics of ruthenates is that both lattice and orbital degrees of freedom are active and are strongly coupled to charge and spin degrees of freedom. Such a complex interplay of multiple degrees of freedom causes the properties of ruthenates to exhibit a gigantic response to external stimuli under certain circumstances. Magnetic field, pressure, and chemical composition all have been demonstrated to be effective in inducing electronic/magnetic phase transitions in ruthenates. Therefore, ruthenates are ideal candidates for searching for novel quantum phenomena through controlling external parameters. The objective of this project is to search for novel quantum phenomena in ruthenate materials using high-quality single crystals grown by the floating-zone technique, and investigate the underlying physics. The following summarizes our accomplishments. We have focused on trilayered Sr4Ru3O10 and bilayered (Ca1-xSrx)3Ru2O7. We have succeeded in growing high-quality single crystals of these materials using the floating-zone technique and performed systematic studies on their electronic and magnetic properties through a variety of measurements, including resistivity, Hall coefficient, angle-resolved magnetoresistivity, Hall probe microscopy, and specific heat. We have also studied microscopic magnetic properties for some of these materials using neutron scattering in collaboration with Los Alamos National Laboratory. We have observed a number of unusual exotic quantum phenomena through these studies, such as an orbital selective metamagnetic transition, bulk spin valve effect, and a heavy-mass nearly ferromagnetic state with a surprisingly large Wilson ratio. Our work has also revealed underlying physics of these exotic phenomena. Exotic phenomena of correlated

  9. Rod Driven Frequency Entrainment and Resonance Phenomena

    Directory of Open Access Journals (Sweden)

    Christina Salchow


    Full Text Available A controversy exists on photic driving in the human visual cortex evoked by intermittent photic stimulation. Frequency entrainment and resonance phenomena are reported for frequencies higher than 12 Hz in some studies while missing in others. We hypothesized that this might be due to different experimental conditions, since both high and low intensity light stimulation were used. However, most studies do not report radiometric measurements, which makes it impossible to categorize the stimulation according to photopic, mesopic, and scotopic vision. Low intensity light stimulation might lead to scotopic vision, where rod perception dominates. In this study, we investigated photic driving for rod-dominated visual input under scotopic conditions. Twelve healthy volunteers were stimulated with low intensity light flashes at 20 stimulation frequencies, leading to rod activation only. The frequencies were multiples of the individual alpha frequency (α of each volunteer in the range from 0.40–2.30*α. 306-channel whole head magnetoencephalography recordings were analyzed in time, frequency, and spatiotemporal domains with the Topographic Matching Pursuit algorithm. We found resonance phenomena and frequency entrainment for stimulations at or close to the individual alpha frequency (0.90–1.10*α and half of the alpha frequency (0.40–0.55*α. No signs of resonance and frequency entrainment phenomena were revealed around 2.00*α. Instead, on-responses at the beginning and off-responses at the end of each stimulation train were observed for the first time in a photic driving experiment at frequencies of 1.30–2.30*α, indicating that the flicker fusion threshold was reached. All results, the resonance and entrainment as well as the fusion effects, provide evidence for rod-dominated photic driving in the visual cortex.

  10. Isotopes in heterogeneous catalysis

    CERN Document Server

    Hargreaves, Justin SJ


    The purpose of this book is to review the current, state-of-the-art application of isotopic methods to the field of heterogeneous catalysis. Isotopic studies are arguably the ultimate technique in in situ methods for heterogeneous catalysis. In this review volume, chapters have been contributed by experts in the field and the coverage includes both the application of specific isotopes - Deuterium, Tritium, Carbon-14, Sulfur-35 and Oxygen-18 - as well as isotopic techniques - determination of surface mobility, steady state transient isotope kinetic analysis, and positron emission profiling.

  11. Results on large transverse momentum phenomena

    CERN Document Server

    Büsser, F W; Blumenfeld, B; Camilleri, L L; Cool, R L; Di Lella, L; Gladding, G; Lederman, Leon Max; Litt, L; Placci, A; Pope, B G; Segler, S L; Smith, A M; Yoh, J K; Zavattini, E


    Preliminary results of an experiment on large transverse momentum phenomena performed at the CERN-ISR at centre-of-mass energies of 52.7 and 44.8 GeV are presented. The topics studied were the inclusive reaction p+p to pi /sup 0/+'anything', where the pi /sup 0/ was emitted around 90 degrees in the centre- of-mass system, ( pi /sup 0/ pi /sup 0/) correlations, and the charged multiplicity associated with large transverse momentum pi /sup 0/'s. In addition, results of a search for electrons and electron pairs are included. (4 refs).

  12. Micro- and nanoscale phenomena in tribology

    CERN Document Server

    Chung, Yip-Wah


    Drawn from presentations at a recent National Science Foundation Summer Institute on Nanomechanics, Nanomaterials, and Micro/Nanomanufacturing, Micro- and Nanoscale Phenomena in Tribology explores the convergence of the multiple science and engineering disciplines involved in tribology and the connection from the macro to nano world. Written by specialists from computation, materials science, mechanical engineering, surface physics, and chemistry, each chapter provides up-to-date coverage of both basic and advanced topics and includes extensive references for further study.After discussing the

  13. Cooperative phenomena in flows; Poster abstracts

    Energy Technology Data Exchange (ETDEWEB)

    Loekseth, Trine (ed.)


    The objective of this 'Geilo School' was to bring together researchers with various interests and background including theoretical experimental physicists, material scientists and molecular biologists to identify and discuss areas where synergism between these disciplines may be most fruitfully applied to the study of various aspects of 'Cooperative phenomena in flows'. There were altogether 21 lecturers at the School with about 80 participants from 19 countries. This was the 21. Geilo School held biannually since the first one in I971. Reference to the earlier Geilo Schools 1971-2009 may be found here: (Author)

  14. Electrical breakdown phenomena of dielectric elastomers

    DEFF Research Database (Denmark)

    Yu, Liyun; Mateiu, Ramona Valentina; Skov, Anne Ladegaard

    years. However, optimization with respect to the dielectric permittivity solely may lead to other problematic phenomena such as premature electrical breakdown. In this work, we focus on the chloro propyl functionalized silicone elastomers prepared in Madsen et al[2] and we investigate the electrical...... breakdown patterns of two similar chloro propyl functionalized silicone elastomers which break down electrically in a rather different way as well as we compare them to a silicone based reference. Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS) are used to evaluate...... the elastomers after electrical breakdown....

  15. Chalcogenides Metastability and Phase Change Phenomena

    CERN Document Server

    Kolobov, Alexander V


    A state-of-the-art description of metastability observed in chalcogenide alloys is presented with the accent on the underlying physics. A comparison is made between sulphur(selenium)-based chalcogenide glasses, where numerous photo-induced phenomena take place entirely within the amorphous phase, and tellurides where a reversible crystal-to-amorphous phase-change transformation is a major effect. Applications of metastability in devices¿optical memories and nonvolatile electronic phase-change random-access memories among others are discussed, including the latest trends. Background material essential for understanding current research in the field is also provided.

  16. Whither the Future of Controlling Quantum Phenomena? (United States)

    Rabitz, Herschel; de Vivie-Riedle, Regina; Motzkus, Marcus; Kompa, Karl


    This review puts into perspective the present state and prospects for controlling quantum phenomena in atoms and molecules. The topics considered include the nature of physical and chemical control objectives, the development of possible quantum control rules of thumb, the theoretical design of controls and their laboratory realization, quantum learning and feedback control in the laboratory, bulk media influences, and the ability to utilize coherent quantum manipulation as a means for extracting microscopic information. The preview of the field presented here suggests that important advances in the control of molecules and the capability of learning about molecular interactions may be reached through the application of emerging theoretical concepts and laboratory technologies.

  17. Heavenly Bodies and Phenomena in Petroglyphs (United States)

    Tokhatyan, Karen


    In Armenian culture are amply reflected realities connected with Universe. Their figurative expressions are also petroglyphs in which there are representations of solar signs, swastika, Moon crescend, planets, stars, star groups, constellations, Milky Way, Earth. Among heavenly and atmospheric phenomena are: eclipce, meteor, comet, ligthning, cloud, rain and rainbow. There are many products of scientific thinking: stellar maps, calendars, compasses, astronomical records, Zodiac signs and ideograms. Thousands of the Armenian petroglyphs that were created millennia ago by an indigenous ethnos - Armenians, point to the significant place of celestial bodies and luminaries, especially the Sun, stars, and stellar constellations in our ancestors' cosmological perceptions.

  18. Highly energetic phenomena in water electrolysis


    Postnikov, A. V.; Uvarov, I. V.; Lokhanin, M. V.; V. B. Svetovoy


    Water electrolysis performed in microsystems with a fast change of voltage polarity produces optically invisible nanobubbles containing H2 and O2 gases. In this form the gases are able to the reverse reaction of water formation. Here we report extreme phenomena observed in a millimeter-sized open system. Under a frequency of driving pulses above 100 kHz the process is accompanied by clicking sounds repeated every 50 ms or so. Fast video reveals that synchronously with the click a bubble is gr...

  19. 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)


    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.

  20. A computer model for one-dimensional mass and energy transport in and around chemically reacting particles, including complex gas-phase chemistry, multicomponent molecular diffusion, surface evaporation, and heterogeneous reaction (United States)

    Cho, S. Y.; Yetter, R. A.; Dryer, F. L.


    Various chemically reacting flow problems highlighting chemical and physical fundamentals rather than flow geometry are presently investigated by means of a comprehensive mathematical model that incorporates multicomponent molecular diffusion, complex chemistry, and heterogeneous processes, in the interest of obtaining sensitivity-related information. The sensitivity equations were decoupled from those of the model, and then integrated one time-step behind the integration of the model equations, and analytical Jacobian matrices were applied to improve the accuracy of sensitivity coefficients that are calculated together with model solutions.

  1. A comparison of thermoelectric phenomena in diverse alloy systems

    Energy Technology Data Exchange (ETDEWEB)

    Cook, Bruce [Iowa State Univ., Ames, IA (United States)


    The study of thermoelectric phenomena in solids provides a wealth of opportunity for exploration of the complex interrelationships between structure, processing, and properties of materials. As thermoelectricity implies some type of coupled thermal and electrical behavior, it is expected that a basic understanding of transport behavior in materials is the goal of such a study. However, transport properties such as electrical resistivity and thermal diffusivity cannot be fully understood and interpreted without first developing an understanding of the material's preparation and its underlying structure. It is the objective of this dissertation to critically examine a number of diverse systems in order to develop a broad perspective on how structure-processing-property relationships differ from system to system, and to discover the common parameters upon which any good thermoelectric material is based. The alloy systems examined in this work include silicon-germanium, zinc oxide, complex intermetallic compounds such as the half-Heusler MNiSn, where M = Ti, Zr, or Hf, and rare earth chalcogenides.

  2. Depinning and heterogeneous dynamics of colloidal crystal layers under shear flow (United States)

    Gerloff, Sascha; Klapp, Sabine H. L.


    Using Brownian dynamics (BD) simulations and an analytical approach we investigate the shear-induced, nonequilibrium dynamics of dense colloidal suspensions confined to a narrow slit-pore. Focusing on situations where the colloids arrange in well-defined layers with solidlike in-plane structure, the confined films display complex, nonlinear behavior such as collective depinning and local transport via density excitations. These phenomena are reminiscent of colloidal monolayers driven over a periodic substrate potential. In order to deepen this connection, we present an effective model that maps the dynamics of the shear-driven colloidal layers to the motion of a single particle driven over an effective substrate potential. This model allows us to estimate the critical shear rate of the depinning transition based on the equilibrium configuration, revealing the impact of important parameters, such as the slit-pore width and the interaction strength. We then turn to heterogeneous systems where a layer of small colloids is sheared with respect to bottom layers of large particles. For these incommensurate systems we find that the particle transport is dominated by density excitations resembling the so-called "kink" solutions of the Frenkel-Kontorova (FK) model. In contrast to the FK model, however, the corresponding "antikinks" do not move.

  3. Syntactic Idioms and Precedent Phenomena: Intersection Zones

    Directory of Open Access Journals (Sweden)

    Hanna Sytar


    Full Text Available Background: One examined mainly structural and semantic features of syntactic idioms so far. The pragmatic dimension of these original units that are on the verge of syntax and phraseology, has not been highlighted properly in the scientific literature, so it needs theoretical understanding. The combination of syntactic idiom and phraseological phenomenon refers to the communication techniques impacting on message recipient. Purpose: to analyze the intersection zones of syntactic idioms and precedent phenomena. Results: Analysis of the collected factual material allows to distinguish two areas of interpenetration of syntactic idioms and precedent units: 1 construction of expression according to the phraseologized model, within which the position of variable component is filled by the precedent name or precedent expression; 2 the model of sentence itself is precedent, and lexical content does not comply with generally known one that does not affect on understanding of model content by recipient. With a combination of syntactic idiom and precedent phenomena speakers provide drawing of recipients’ attention, carry out a hidden influence on them, express their own attitude to the realities, so that perform phatic, manipulative and expressive-evaluative functions. The modifications and transformations of precedent expressions and names appeared to be regular in such interpenetrations. Discussion: The obtained results reflect the general trend towards transform (transformation, modification, variation, etc. of precedent, as well as phraseological units, and can be used for the analysis of patterns of their formation and modifications. Further research phase implies tracing patterns of syntactic idioms combination with other means of expressive syntax.

  4. WHC natural phenomena hazards mitigation implementation plan

    Energy Technology Data Exchange (ETDEWEB)

    Conrads, T.J.


    Natural phenomena hazards (NPH) are unexpected acts of nature which pose a threat or danger to workers, the public or to the environment. Earthquakes, extreme winds (hurricane and tornado),snow, flooding, volcanic ashfall, and lightning strike are examples of NPH at Hanford. It is the policy of U.S. Department of Energy (DOE) to design, construct and operate DOE facilitiesso that workers, the public and the environment are protected from NPH and other hazards. During 1993 DOE, Richland Operations Office (RL) transmitted DOE Order 5480.28, ``Natural Phenomena Hazards Mitigation,`` to Westinghouse Hanford COmpany (WHC) for compliance. The Order includes rigorous new NPH criteria for the design of new DOE facilities as well as for the evaluation and upgrade of existing DOE facilities. In 1995 DOE issued Order 420.1, ``Facility Safety`` which contains the same NPH requirements and invokes the same applicable standards as Order 5480.28. It will supersede Order 5480.28 when an in-force date for Order 420.1 is established through contract revision. Activities will be planned and accomplished in four phases: Mobilization; Prioritization; Evaluation; and Upgrade. The basis for the graded approach is the designation of facilities/structures into one of five performance categories based upon safety function, mission and cost. This Implementation Plan develops the program for the Prioritization Phase, as well as an overall strategy for the implemention of DOE Order 5480.2B.

  5. Shock Wave Diffraction Phenomena around Slotted Splitters

    Directory of Open Access Journals (Sweden)

    Francesca Gnani


    Full Text Available In the field of aerospace engineering, the study of the characteristics of vortical flows and their unsteady phenomena finds numerous engineering applications related to improvements in the design of tip devices, enhancement of combustor performance, and control of noise generation. A large amount of work has been carried out in the analysis of the shock wave diffraction around conventional geometries such as sharp and rounded corners, but the employment of splitters with lateral variation has hardly attracted the attention of researchers. The investigation of this phenomenon around two-dimensional wedges has allowed the understanding of the basic physical principles of the flow features. On the other hand, important aspects that appear in the third dimension due to the turbulent nature of the vortices are omitted. The lack of studies that use three-dimensional geometries has motivated the current work to experimentally investigate the evolution of the shock wave diffraction around two splitters with spike-shaped structures for Mach numbers of 1.31 and 1.59. Schlieren photography was used to obtain an insight into the sequential diffraction processes that take place in different planes. Interacting among them, these phenomena generate a complicated turbulent cloud with a vortical arrangement.

  6. Uncommon corrosion phenomena of archaeological bronze alloys (United States)

    Ingo, G. M.; de Caro, T.; Riccucci, C.; Khosroff, S.


    In the framework of the EFESTUS project (funded by the European Commission, contract No. ICA3-CT-2002-10030) the corrosion products of a large number of archaeological bronze artefacts are investigated by means of the combined use of scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD) and optical microscopy (OM) and tentative correlation of their nature with the chemical composition of the artefacts and the burial context is proposed. The results provide good insight into the corrosion layers and evidence in some bronze Roman coins and artefacts; the occurrence of uncommon corrosion phenomena that give rise to the formation of a yellowish-green complex chlorine-phosphate of lead (pyromorphite, (PbCl)Pb4(PO4)3) and of a gold-like thick layer of an iron and copper sulphide (chalcopyrite, CuFeS2). The micro-chemical and micro-structural results show that the coins were buried in a soil enriched in phosphorus for the accidental presence of a large amount of decomposing fragments of bones or in an anaerobic and humus rich soil where the chalcopyrite layer has been produced via the interaction between the iron of the soil, the copper of the coin and the sulphur produced by the decomposition of organic matter in an almost oxygen free environment. Finally, some unusual periodic corrosion phenomena occurring in high tin bronze mirrors found at Zama (Tunisia) are described.

  7. Heterogeneity and option pricing

    NARCIS (Netherlands)

    Benninga, Simon; Mayshar, Joram


    An economy with agents having constant yet heterogeneous degrees of relative risk aversion prices assets as though there were a single decreasing relative risk aversion pricing representative agent. The pricing kernel has fat tails and option prices do not conform to the Black-Scholes formula.

  8. Why does heterogeneity matter? (United States)

    K.B. Pierce


    This is a review of the book "Ecosystem function in heterogeneous landscapes" published in 2005. The authors are G. Lovett, C. Jones, M.G. Turner, and K.C. Weathers. It was published by Springer, New York. The book is a synthesis of the 10th Gary conference held at the Institute of Ecosystem Studies in Millbrook, New York, in 2003.

  9. Heterogeneous chromium catalysts

    NARCIS (Netherlands)


    The present invention relates to a heterogeneous chromium catalyst system for the polymerisation of ethylene and/or alpha olefins prepared by the steps of: (a) providing a silica-containing support, (b) treating the silica-containing support with a chromium compound to form a chromium-based

  10. Receiver Heterogeneity Helps

    DEFF Research Database (Denmark)

    Kovács, Erika R.; Pedersen, Morten Videbæk; Roetter, Daniel Enrique Lucani


    Heterogeneity amongst devices and desired service are commonly seen as a source of additional challenges for setting up an efficient multi-layer multicast service. In particular, devices requiring only the base layer can become a key bottleneck to the performance for other devices. This paper...

  11. Heterogeneity of Intellectual Assets

    DEFF Research Database (Denmark)

    Dahlgren, Johan Henrich; Lund Jensen, Rasmus; Valentin, Finn


    This paper deals with methodological issues of assessing the composition and level ofheterogeneity of firms' intellectual assets. It develops an original metric - referred to asthe H-index - for measuring heterogeneity using data extracted from patent documents.The main purpose is to improve...

  12. Quantifying hidden individual heterogeneity

    DEFF Research Database (Denmark)

    Steiner, Ulrich; Lenart, Adam; Vaupel, James W.

    Aging is assumed to be driven by the accumulation of damage or some other aging factor which shapes demographic patterns, including the classical late age mortality plateaus. However to date, heterogeneity in these damage stages is not observed. Here, we estimate underlying stage distributions...

  13. Heterogeneity of Dutch rainfall

    NARCIS (Netherlands)

    Witter, J.V.


    Rainfall data for the Netherlands have been used in this study to investigate aspects of heterogeneity of rainfall, in particular local differences in rainfall levels, time trends in rainfall, and local differences in rainfall trend. The possible effect of urbanization and industrialization on the

  14. Heterogeneous computing in economics

    DEFF Research Database (Denmark)

    Dziubinski, Matt P.; Grassi, Stefano


    This paper shows the potential of heterogeneous computing in solving dynamic equilibrium models in economics. We illustrate the power and simplicity of C++ Accelerated Massive Parallelism (C++ AMP) recently introduced by Microsoft. Starting from the same exercise as Aldrich et al. (J Econ Dyn...

  15. Scales of mantle heterogeneity (United States)

    Moore, J. C.; Akber-Knutson, S.; Konter, J.; Kellogg, J.; Hart, S.; Kellogg, L. H.; Romanowicz, B.


    A long-standing question in mantle dynamics concerns the scale of heterogeneity in the mantle. Mantle convection tends to both destroy (through stirring) and create (through melt extraction and subduction) heterogeneity in bulk and trace element composition. Over time, these competing processes create variations in geochemical composition along mid-oceanic ridges and among oceanic islands, spanning a range of scales from extremely long wavelength (for example, the DUPAL anomaly) to very small scale (for example, variations amongst melt inclusions). While geochemical data and seismic observations can be used to constrain the length scales of mantle heterogeneity, dynamical mixing calculations can illustrate the processes and timescales involved in stirring and mixing. At the Summer 2004 CIDER workshop on Relating Geochemical and Seismological Heterogeneity in the Earth's Mantle, an interdisciplinary group evaluated scales of heterogeneity in the Earth's mantle using a combined analysis of geochemical data, seismological data and results of numerical models of mixing. We mined the PetDB database for isotopic data from glass and whole rock analyses for the Mid-Atlantic Ridge (MAR) and the East Pacific Rise (EPR), projecting them along the ridge length. We examined Sr isotope variability along the East Pacific rise by looking at the difference in Sr ratio between adjacent samples as a function of distance between the samples. The East Pacific Rise exhibits an overall bowl shape of normal MORB characteristics, with higher values in the higher latitudes (there is, however, an unfortunate gap in sampling, roughly 2000 km long). These background characteristics are punctuated with spikes in values at various locations, some, but not all of which are associated with off-axis volcanism. A Lomb-Scargle periodogram for unevenly spaced data was utilized to construct a power spectrum of the scale lengths of heterogeneity along both ridges. Using the same isotopic systems (Sr, Nd

  16. Next Generation Nuclear Plant Phenomena Identification and Ranking Tables (PIRTs) Volume 1: Main Report

    Energy Technology Data Exchange (ETDEWEB)

    Ball, Sydney J [ORNL


    A phenomena identification and ranking table (PIRT) process was conducted for the Next Generation Nuclear Plant (NGNP) design. This design (in the conceptual stage) is a modular high-temperature gas-cooled reactor (HTGR) that generates both electricity and process heat for hydrogen production. Expert panels identified safety-relevant phenomena, ranked their importance, and assessed the knowledge levels in the areas of accidents and thermal fluids, fission-product transport and dose, high-temperature materials, graphite, and process heat for hydrogen production. This main report summarizes and documents the process and scope of the reviews, noting the major activities and conclusions. The identified phenomena, analyses, rationales, and associated ratings of the phenomena, plus a summary of each panel's findings, are presented. Individual panel reports for these areas are provided as attached volumes to this main report and provide considerably more detail about each panel's deliberations as well as a more complete listing of the phenomena that were evaluated.

  17. Analysis CFD for the hydrogen transport in the primary containment of a BWR; Analisis CFD para el transporte de hidrogeno en la contencion primaria de un reactor BWR

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez P, D. A.; Del Valle G, E. [IPN, Escuela Superior de Fisica y Matematicas, Av. IPN s/n, Edificio 9, Col. San Pedro Zacatenco, 07738 Mexico D. F. (Mexico); Gomez T, A. M., E-mail: [ININ, Departamento de Sistemas Nucleares, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)


    This study presents a qualitative and quantitative comparison among the CFD GASFLOW and OpenFOAM codes which are related with the phenomenon of hydrogen transport and other gases in the primary containment of a Boiling Water Reactor (BWR). GASFLOW is a commercial license code that is well validated and that was developed in Germany for the analysis of the gases transport in containments of nuclear reactors. On the other hand, OpenFOAM is an open source code that offers several evaluation solvers for different types of phenomena; in this case, the solver reacting-Foam is used to analyze the hydrogen transport inside the primary containment of the BWR. The results that offer the solver reacting-Foam of OpenFOAM are evaluated in the hydrogen transport calculation and the results are compared with those of the program of commercial license GASFLOW to see if is viable the use of the open source code in the case of the hydrogen transport in the primary containment of a BWR. Of the obtained results so much quantitative as qualitative some differences were identified between both codes, the differences (with a percentage of maximum error of 4%) in the quantitative results are small and they are considered acceptable for this analysis type, also, these differences are attributed mainly to the used transport models, considering that OpenFOAM uses a homogeneous model and GASFLOW uses a heterogeneous model. (Author)

  18. A kinetic-MHD model for low frequency phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, C.Z.


    A hybrid kinetic-MHD model for describing low-frequency phenomena in high beta anisotropic plasmas that consist of two components: a low energy core component and an energetic component with low density. The kinetic-MHD model treats the low energy core component by magnetohydrodynamic (MHD) description, the energetic component by kinetic approach such as the gyrokinetic equation, and the coupling between the dynamics of these two components through plasma pressure in the momentum equation. The kinetic-MHD model optimizes both the physics contents and the theoretical efforts in studying low frequency MHD waves and transport phenomena in general magnetic field geometries, and can be easily modified to include the core plasma kinetic effects if necessary. It is applicable to any magnetized collisionless plasma system where the parallel electric field effects are negligibly small. In the linearized limit two coupled eigenmode equations for describing the coupling between the transverse Alfven type and the compressional Alfven type waves are derived. The eigenmode equations are identical to those derived from the full gyrokinetic equation in the low frequency limit and were previously analyzed both analytically nd numerically to obtain the eigenmode structure of the drift mirror instability which explains successfully the multi-satellite observation of antisymmetric field-aligned structure of the compressional magnetic field of Pc 5 waves in the magnetospheric ring current plasma. Finally, a quadratic form is derived to demonstrate the stability of the low-frequency transverse and compressional Alfven type instabilities in terms of the pressure anisotropy parameter {tau} and the magnetic field curvature-pressure gradient parameter. A procedure for determining the stability of a marginally stable MHD wave due to wave-particle resonances is also presented.

  19. Mathematical methods of studying physical phenomena (United States)

    Man'ko, Margarita A.


    In recent decades, substantial theoretical and experimental progress was achieved in understanding the quantum nature of physical phenomena that serves as the foundation of present and future quantum technologies. Quantum correlations like the entanglement of the states of composite systems, the phenomenon of quantum discord, which captures other aspects of quantum correlations, quantum contextuality and, connected with these phenomena, uncertainty relations for conjugate variables and entropies, like Shannon and Rényi entropies, and the inequalities for spin states, like Bell inequalities, reflect the recently understood quantum properties of micro and macro systems. The mathematical methods needed to describe all quantum phenomena mentioned above were also the subject of intense studies in the end of the last, and beginning of the new, century. In this section of CAMOP 'Mathematical Methods of Studying Physical Phenomena' new results and new trends in the rapidly developing domain of quantum (and classical) physics are presented. Among the particular topics under discussion there are some reviews on the problems of dynamical invariants and their relations with symmetries of the physical systems. In fact, this is a very old problem of both classical and quantum systems, e.g. the systems of parametric oscillators with time-dependent parameters, like Ermakov systems, which have specific constants of motion depending linearly or quadratically on the oscillator positions and momenta. Such dynamical invariants play an important role in studying the dynamical Casimir effect, the essence of the effect being the creation of photons from the vacuum in a cavity with moving boundaries due to the presence of purely quantum fluctuations of the electromagnetic field in the vacuum. It is remarkable that this effect was recently observed experimentally. The other new direction in developing the mathematical approach in physics is quantum tomography that provides a new vision of

  20. Physical Simulation: Testing the PHYSICALITY of Phenomena (United States)

    Srivastava, Jagdish


    Theories of Quantum Mechanics in which `consciousness' plays a role have been around for decades. For example, Wheeler maintains that no phenomenon is a real phenomenon unless it has been observed. Also, the von Neumann chain, where the wave function is said to collapse when the chain reaches the mind of a conscious observer, is well known. The author's theory of Quantum Reality (denoted by TK) goes a bit further, saying that at the fundamental levels, all phenomena are logical-mathematical objects only, and the experience of their `physicality' is due to the consciousness of the observer. This paper addresses the question, as to how TK (and, the other related theories) could be tested. A procedure for this, termed `Physical Simulation' is proposed. The idea is to create logical-mathematical objects through a computer. Various aspects of this methodology are discussed.

  1. Noise-driven phenomena in hysteretic systems

    CERN Document Server

    Dimian, Mihai


    Noise-Driven Phenomena in Hysteretic Systems provides a general approach to nonlinear systems with hysteresis driven by noisy inputs, which leads to a unitary framework for the analysis of various stochastic aspects of hysteresis. This book includes integral, differential and algebraic models that are used to describe scalar and vector hysteretic nonlinearities originating from various areas of science and engineering. The universality of the authors approach is also reflected by the diversity of the models used to portray the input noise, from the classical Gaussian white noise to its impulsive forms, often encountered in economics and biological systems, and pink noise, ubiquitous in multi-stable electronic systems. The book is accompanied by HysterSoft© - a robust simulation environment designed to perform complex hysteresis modeling – that can be used by the reader to reproduce many of the results presented in the book as well as to research both disruptive and constructive effects of noise in hysteret...

  2. Heat Transfer Phenomena of Supercritical Fluids

    Energy Technology Data Exchange (ETDEWEB)

    Krau, Carmen Isabella; Kuhn, Dietmar; Schulenberg, Thomas [Forschungszentrum Karlsruhe, Institute for Nuclear and Energy Technologies, 76021 Karlsruhe (Germany)


    In concepts for supercritical water cooled reactors, the reactor core is cooled and moderated by water at supercritical pressures. The significant temperature dependence of the fluid properties of water requires an exact knowledge of the heat transfer mechanism to avoid fuel pin damages. Near the pseudo-critical point a deterioration of heat transfer might happen. Processes, that take place in this case, are not fully understood and are due to be examined systematically. In this paper a general overview on the properties of supercritical water is given, experimental observations of different authors will be reviewed in order to identify heat transfer phenomena and onset of occurrence. The conceptional design of a test rig to investigate heat transfer in the boundary layer will be discussed. Both, water and carbon dioxide, may serve as operating fluids. The loop, including instrumentation and safety devices, is shown and suitable measuring methods are described. (authors)

  3. Astrophysical disks Collective and Stochastic Phenomena

    CERN Document Server

    Fridman, Alexei M; Kovalenko, Ilya G


    The book deals with collective and stochastic processes in astrophysical discs involving theory, observations, and the results of modelling. Among others, it examines the spiral-vortex structure in galactic and accretion disks , stochastic and ordered structures in the developed turbulence. It also describes sources of turbulence in the accretion disks, internal structure of disk in the vicinity of a black hole, numerical modelling of Be envelopes in binaries, gaseous disks in spiral galaxies with shock waves formation, observation of accretion disks in a binary system and mass distribution of luminous matter in disk galaxies. The editors adaptly brought together collective and stochastic phenomena in the modern field of astrophysical discs, their formation, structure, and evolution involving the methodology to deal with, the results of observation and modelling, thereby advancing the study in this important branch of astrophysics and benefiting Professional Researchers, Lecturers, and Graduate Students.

  4. Stochastic phenomena in a fiber Raman amplifier

    CERN Document Server

    Kalashnikov, Vladimir; Ania-Castanón, Juan Diego; Jacobsen, Gunnar; Popov, Sergei


    The interplay of such cornerstones of modern nonlinear fiber optics as a nonlinearity, stochasticity and polarization leads to variety of the noise induced instabilities including polarization attraction and escape phenomena harnessing of which is a key to unlocking the fiber optic systems specifications required in high resolution spectroscopy, metrology, biomedicine and telecommunications. Here, by using direct stochastic modeling, the mapping of interplay of the Raman scattering-based nonlinearity, the random birefringence of a fiber, and the pump-to-signal intensity noise transfer has been done in terms of the fiber Raman amplifier parameters, namely polarization mode dispersion, the relative intensity noise of the pump laser, fiber length, and the signal power. The obtained results reveal conditions for emergence of the random birefringence-induced resonance-like enhancement of the gain fluctuations (stochastic anti-resonance) accompanied by pulse broadening and rare events in the form of low power outpu...

  5. Autistic phenomena in The Adventures of Pinocchio. (United States)

    Smith, Adrian


    This paper seeks to demonstrate that the protagonist of Carlo Collodi's The Adventures of Pinocchio illustrates numerous autistic phenomena such as communication difficulties, sensory and perceptual distortions and mindblindness. While Pinocchio is viewed as a literary construct with contraindications of autism, it will be argued that his autistic traits are sufficient to suggest the possibility that Collodi had a partial intuition of the syndrome 60 years before it was identified by Leo Kanner. Approaching Collodi's text in this manner is taken as an opportunity to survey and reflect upon the psychoanalytic literature on autism and to position it in relation to contemporary theories from cognitive neuroscience. © 2017, The Society of Analytical Psychology.

  6. Nonlinear dynamic phenomena in the beer model

    DEFF Research Database (Denmark)

    Mosekilde, Erik; Laugesen, Jakob Lund


    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......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...... are distinctly different from those observed in smooth systems. We show how the model displays abrupt Hopf and period-doubling bifurcations, truncated bifurcation cascades, and various border-collision bifurcations. The latter allow direct transitions from periodic to chaotic dynamics. Bifurcation phenomena...

  7. Discrete computational mechanics for stiff phenomena

    KAUST Repository

    Michels, Dominik L.


    Many natural phenomena which occur in the realm of visual computing and computational physics, like the dynamics of cloth, fibers, fluids, and solids as well as collision scenarios are described by stiff Hamiltonian equations of motion, i.e. differential equations whose solution spectra simultaneously contain extremely high and low frequencies. This usually impedes the development of physically accurate and at the same time efficient integration algorithms. We present a straightforward computationally oriented introduction to advanced concepts from classical mechanics. We provide an easy to understand step-by-step introduction from variational principles over the Euler-Lagrange formalism and the Legendre transformation to Hamiltonian mechanics. Based on such solid theoretical foundations, we study the underlying geometric structure of Hamiltonian systems as well as their discrete counterparts in order to develop sophisticated structure preserving integration algorithms to efficiently perform high fidelity simulations.

  8. Modeling electrical dispersion phenomena in Earth materials

    Directory of Open Access Journals (Sweden)

    D. Patella


    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.

  9. Electrical breakdown phenomena of dielectric elastomers

    DEFF Research Database (Denmark)

    Yu, Liyun; Mateiu, Ramona Valentina; Skov, Anne Ladegaard

    years. However, optimization with respect to the dielectric permittivity solely may lead to other problematic phenomena such as premature electrical breakdown. In this work, we focus on the chloro propyl functionalized silicone elastomers prepared in Madsen et al[2] and we investigate the electrical...... breakdown patterns of two similar chloro propyl functionalized silicone elastomers which break down electrically in a rather different way as well as we compare them to a silicone based reference. Thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) are used to evaluate the elastomers...... before and after electrical breakdown. It was shown the chemically very similar silicone elastomers broke down electrically in very different ways. These observations emphasize that the modification of the silicone backbone may open up for completely new possibilities for stabilizing the silicone...

  10. Characterizing critical phenomena via the Purcell effect (United States)

    Silva Neto, M. B.; Szilard, D.; Rosa, F. S. S.; Farina, C.; Pinheiro, F. A.


    We investigate the role of phase transitions into the spontaneous-emission rate of a single quantum emitter embedded in a critical medium. Using a Landau-Ginzburg approach, we find that in the broken symmetry phase, the emission rate is reduced, or even suppressed, due to the photon mass generated by the Higgs mechanism. Remarkably, its sensitivity to the critical exponents of the phase transition allows for an optical determination of universality classes. When applied to the cases of superconductivity and superfluidity, we show that the Purcell effect also provides valuable information on spectroscopic and thermodynamic quantities, such as the size of the superconducting gap and the discontinuity in the specific heat at the transition. By unveiling that a deeper connection between the Purcell effect and phase transitions exists, we demonstrate that the former is an efficient optical probe of distinct critical phenomena and their associated observables.

  11. Quantum field theory and critical phenomena

    CERN Document Server

    Zinn-Justin, Jean


    Over the last twenty years quantum field theory has become not only the framework for the discussion of all fundamental interactions except gravity, but also for the understanding of second-order phase transitions in statistical mechanics. This advanced text is based on graduate courses and summer schools given by the author over a number of years. It approaches the subject in terms of path and functional intergrals, adopting a Euclidean metric and using the language of partition and correlation functions. Renormalization and the renormalization group are examined, as are critical phenomena and the role of instantons. Changes for this edition 1. Extensive revision to eliminate a few bugs that had survived the second edition and (mainly) to improve the pedagogical presentation, as a result of experience gathered by lecturing. 2. Additional new topics; holomorphic or coherent state path integral; functional integral and representation of the field theory S-matrix in the holomorphic formalis; non-relativistic li...

  12. Understanding protein adsorption phenomena at solid surfaces. (United States)

    Rabe, Michael; Verdes, Dorinel; Seeger, Stefan


    Protein adsorption at solid surfaces plays a key role in many natural processes and has therefore promoted a widespread interest in many research areas. Despite considerable progress in this field there are still widely differing and even contradictive opinions on how to explain the frequently observed phenomena such as structural rearrangements, cooperative adsorption, overshooting adsorption kinetics, or protein aggregation. In this review recent achievements and new perspectives on protein adsorption processes are comprehensively discussed. The main focus is put on commonly postulated mechanistic aspects and their translation into mathematical concepts and model descriptions. Relevant experimental and computational strategies to practically approach the field of protein adsorption mechanisms and their impact on current successes are outlined. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. Meteorological phenomena in Western classical orchestral music (United States)

    Williams, P. D.; Aplin, K. L.


    The creative output of composers, writers, and artists is often influenced by their surroundings. To give a literary example, it has been claimed recently that some of the characters in Oliver Twist and A Christmas Carol were based on real-life people who lived near Charles Dickens in London. Of course, an important part of what we see and hear is not only the people with whom we interact, but also our geophysical surroundings. Of all the geophysical phenomena to influence us, the weather is arguably the most significant, because we are exposed to it directly and daily. The weather was a great source of inspiration for Monet, Constable, and Turner, who are known for their scientifically accurate paintings of the skies. But to what extent does weather inspire composers? The authors of this presentation, who are atmospheric scientists by day but amateur classical musicians by night, have been contemplating this question. We have built a systematic musical database, which has allowed us to catalogue and analyze the frequencies with which weather is depicted in a sample of classical orchestral music. The depictions vary from explicit mimicry using traditional and specialized orchestral instruments, through to subtle suggestions. We have found that composers are generally influenced by their own environment in the type of weather they choose to represent. As befits the national stereotype, British composers seem disproportionately keen to depict the UK's variable weather patterns and stormy coastline. Reference: Aplin KL and Williams PD (2011) Meteorological phenomena in Western classical orchestral music. Weather, 66(11), pp 300-306. doi:10.1002/wea.765

  14. APRI-6. Accident Phenomena of Risk Importance

    Energy Technology Data Exchange (ETDEWEB)

    Garis, Ninos; Ljung, J (eds.) (Swedish Radiation Safety Authority, Stockholm (Sweden)); Agrenius, Lennart (ed.) (Agrenius Ingenjoersbyraa AB, Stockholm (Sweden))


    Since the early 1980s, nuclear power utilities in Sweden and the Swedish Radiation Safety Authority (SSM) collaborate on the research in severe reactor accidents. In the beginning focus was mostly on strengthening protection against environmental impacts after a severe reactor accident, for example by develop systems for the filtered relief of the reactor containment. Since the early 90s, this focus has shifted to the phenomenological issues of risk-dominant significance. During the years 2006-2008, the partnership continued in the research project APRI-6. The aim was to show whether the solutions adopted in the Swedish strategy for incident management provides adequate protection for the environment. This is done by studying important phenomena in the core melt estimating the amount of radioactivity that can be released to the atmosphere in a severe accident. To achieve these objectives the research has included monitoring of international research on severe accidents and evaluation of results and continued support for research of severe accidents at the Royal Inst. of Technology (KTH) and Chalmers University. The follow-up of international research has promoted the exchange of knowledge and experience and has given access to a wealth of information on various phenomena relevant to events in severe accidents. The continued support to KTH has provided increased knowledge about the possibility of cooling the molten core in the reactor tank and the processes associated with coolability in the confinement and about steam explosions. Support for Chalmers has increased knowledge of the accident chemistry, mainly the behavior of iodine and ruthenium in the containment after an accident.

  15. Information and Heterogeneous Beliefs

    DEFF Research Database (Denmark)

    Christensen, Peter Ove; Qin, Zhenjiang


    In an incomplete market with heterogeneous prior beliefs, we show public information can have a substantial impact on the ex ante cost of capital, trading volume, and investor welfare. The Pareto effcient public information system is the system enjoying the maximum ex ante cost of capital...... ante risk premium is unaffected by the informativeness of the public information system. Similar results are obtained in a production economy, but the impact on the ex ante cost of capital is dampened compared to the exchange economy due to welfare improving reductions in real investments to smooth...... and the maximum expected abnormal trading volume. Imperfect public information increases the gains-to-trade based on heterogeneously updated posterior beliefs. In an exchange economy, this leads to higher growth in the investors' certainty equivalents and, thus, a higher equilibrium interest rate, whereas the ex...

  16. HSM: Heterogeneous Subspace Mining in High Dimensional Data

    DEFF Research Database (Denmark)

    Müller, Emmanuel; Assent, Ira; Seidl, Thomas


    Heterogeneous data, i.e. data with both categorical and continuous values, is common in many databases. However, most data mining algorithms assume either continuous or categorical attributes, but not both. In high dimensional data, phenomena due to the "curse of dimensionality" pose additional...... challenges. Usually, due to locally varying relevance of attributes, patterns do not show across the full set of attributes. In this paper we propose HSM, which defines a new pattern model for heterogeneous high dimensional data. It allows data mining in arbitrary subsets of the attributes that are relevant...... for the respective patterns. Based on this model we propose an efficient algorithm, which is aware of the heterogeneity of the attributes. We extend an indexing structure for continuous attributes such that HSM indexing adapts to different attribute types. In our experiments we show that HSM efficiently mines...

  17. Sequence heterogeneity accelerates protein search for targets on DNA

    Energy Technology Data Exchange (ETDEWEB)

    Shvets, Alexey A.; Kolomeisky, Anatoly B., E-mail: [Department of Chemistry and Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005 (United States)


    The process of protein search for specific binding sites on DNA is fundamentally important since it marks the beginning of all major biological processes. We present a theoretical investigation that probes the role of DNA sequence symmetry, heterogeneity, and chemical composition in the protein search dynamics. Using a discrete-state stochastic approach with a first-passage events analysis, which takes into account the most relevant physical-chemical processes, a full analytical description of the search dynamics is obtained. It is found that, contrary to existing views, the protein search is generally faster on DNA with more heterogeneous sequences. In addition, the search dynamics might be affected by the chemical composition near the target site. The physical origins of these phenomena are discussed. Our results suggest that biological processes might be effectively regulated by modifying chemical composition, symmetry, and heterogeneity of a genome.

  18. Investigation research on the evaluation of a coupled thermo-hydro-mechanical-chemical phenomena. Result report

    Energy Technology Data Exchange (ETDEWEB)

    Chijimatsu, Masakazu; Amemiya, Kiyoshi; Shiozaki, Isao [Hazama Corp., Tokyo (Japan); Neyama, Atsushi; Iwata, Hiroshi; Nakagawa, Koichi [Computer Software Development Co.Ltd. (Japan); Ishihara, Yoshinao; Sagawa, Hiroshi [Mitsubishi Heavy Industries Ltd., Tokyo (Japan)


    In order to realize a coupling analysis in the near field of the geological disposal system, this study has been studied on the addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES) and preliminary coupling analysis by using development environmental tool (Diffpack) for numerical analysis. (1) In order to prepare the strategy on the addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES), we have studied on the requirement of THAMES-Transport and methodology of coupling analysis. After that we set out modification plan by the Eulerian-Lagrangian (EL) method. (2) Based on the document of modification plan, we have done addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES) and carried out verification analysis in order to confirm on the accuracy of THAMES-Transport. (3) In order to understand on the behavior of NaCl in the porewater under the coupled thermo-hydro-mechanical phenomena in the HLW engineered barrier system, we have calculated coupling phenomenon by using THAMES-Transport. Transportation and concentration phenomena of NaCl are calculated but precipitation of NaCl is not occurred under the analysis conditions in this report. (4) In order to confirm about feasibility of coupling analysis under the development environmental tool (Diffpack) for numerical analysis, we have carried out on the design work and writing program of the preliminary coupling system. In this study, we have adopted existing transport model (HYDROGEOCHEM) and geochemical model (phreeqe 60) for preliminary coupling system. (5) In order to confirm program correctness of preliminary coupling system, we have carried out benchmarking analysis by using existing reactive-transport analysis code (HYDROGEOCHEM). (6) We have been prepared short-range development plan based on through the modification study of THAMES and writing program of the preliminary coupling

  19. Investigation research on the evaluation of a coupled thermo-hydro-mechanical-chemical phenomena. Outline report

    Energy Technology Data Exchange (ETDEWEB)

    Chijimatsu, Masakazu; Amemiya, Kiyoshi [Hazama Corp., Tokyo (Japan); Neyama, Atsushi; Iwata, Hiroshi; Nakagawa, Koichi [Computer Software Development Co., Ltd., Tokyo (Japan); Ishihara, Yoshinao; Shiozaki, Isao; Sagawa, Hiroshi [Mitsubishi Heavy Industries, LTD., Tokyo (Japan)


    In order to realize a coupling analysis in the near field of the geological disposal system, this study has been studied on the addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES) and preliminary coupling analysis by using development environmental tool (Diffpack) for numerical analysis. (1) In order to prepare the strategy on the addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES), we have studied on the requirement of THAMES-Transport and methodology of coupling analysis. After that we set out modification plan by the Eulerian-Lagrangian (EL) method. (2) Based on the document of modification plan, we have done addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES) and carried out verification analysis in order to confirm on the accuracy of THAMES-Transport. (3) In order to understand on the behavior of NaCl in the porewater under the coupled thermo-hydro-mechanical phenomena in the HLW engineered barrier system, we have calculated coupling phenomenon by using THAMES-Transport. Transportation and concentration phenomena of NaCl are calculated but precipitation of NaCl is not occurred under the analysis conditions in this report. (4) In order to confirm about feasibility of coupling analysis under the development environmental tool (Diffpack) for numerical analysis, we have carried out on the design work and writing program of the preliminary coupling system. In this study, we have adopted existing transport model (HYDROGEOCHEM) and geochemical model (phreeqe60) for preliminary coupling system. (5) In order to confirm program correctness of preliminary coupling system, we have carried out benchmarking analysis by using existing reactive-transport analysis code (HYDROGEOCHEM). (6) We have been prepared short-range development plan based on through the modification study of THAMES and writing program of the preliminary coupling



    the “product component” is a result of technology push only, it struggles to fit into a conservative system environment . If the “product component...makes the categorization difficult. In a technology push environment , the evolution of technology is easier to track since it starts evolving from a... environmental information. The role of the heterogeneous integration technology for reducing the size and the power consumption of small sensors was studied

  1. Micromechanics of heterogeneous materials

    CERN Document Server

    Buryachenko, Valeriy


    Here is an accurate and timely account of micromechanics, which spans materials science, mechanical engineering, applied mathematics, technical physics, geophysics, and biology. The book features rigorous and unified theoretical methods of applied mathematics and statistical physics in the material science of microheterogeneous media. Uniquely, it offers a useful demonstration of the systematic and fundamental research of the microstructure of the wide class of heterogeneous materials of natural and synthetic nature.

  2. Heterogeneous chromium catalysts



    The present invention relates to a heterogeneous chromium catalyst system for the polymerisation of ethylene and/or alpha olefins prepared by the steps of: (a) providing a silica-containing support, (b) treating the silica-containing support with a chromium compound to form a chromium-based silica-containing support, (c) activating the chromium-based silica-containing support, (d) chemically reducing the activated chromium-based silica-containing support to produce a precursor catalyst, (e) r...

  3. Noise-Driven Phenotypic Heterogeneity with Finite Correlation Time in Clonal Populations


    Lee, U.; Skinner, J.J.; Reinitz, J.; Rosner, M.R.; Kim, E-J.


    There has been increasing awareness in the wider biological community of the role of clonal phenotypic heterogeneity in playing key roles in phenomena such as cellular bet-hedging and decision making, as in the case of the phage-λ lysis/lysogeny and B. Subtilis competence/vegetative pathways. Here, we report on the effect of stochasticity in growth rate, cellular memory/intermittency, and its relation to phenotypic heterogeneity. We first present a linear stochastic differential model with fi...

  4. Modeling Mantle Heterogeneity Development in Earth's Mantle Using Multidisciplinary Approaches (United States)

    de Silva, S. M. S.; Finlayson, V.; Gu, T.; Li, M.; Lithgow-Bertelloni, C. R.; Cormier, V. F.


    The process of subduction provides continuous chemical and thermal heterogeneity to Earth's mantle. How heterogeneity is stirred, stretched and distributed depends on the detail of mantle convection as well as chemical and physical properties of mantle materials. Seismic observations have revealed heterogeneities in Earth's mantle at varying scales. Seismic velocities are controlled by physical parameters such as density, bulk modulus and shear modulus, which are a function of temperature, pressure and composition. Thus, understanding the origin of seismic heterogeneities play an important role in understanding the thermal and chemical state of the present Earth's mantle. Originating from the CIDER 2014 workshop, our goal is to take a multidisciplinary approach to tackle a variety of questions, foremost what length scales of heterogeneity might we expect from the convecting process and how do they manifest themselves in seismic imaging. This touches upon fundamental issues such as the composition of the mantle, the nature of stirring and mixing, and the nature of large-scale mantle upwellings (LLSVPs). We will investigate the development of heterogeneity in response to various compositions and redox states using existing and new thermochemical mantle convection simulations, and test the sensitivity of seismic measurements to different length scales of chemical heterogeneity. We try to reconcile large differences in length scales of heterogeneity as well as fractional perturbations of seismic velocity and density predicted by tomography and scattering seismic experiments. Preliminary results from the CIDER workshop initiate with conversion of geodynamic models to profiles of seismic velocity and density which are then taken as input models to predict multiply scattered, high frequency, P wave coda envelopes synthesized by a radiative transport technique. The predicted sensitivity of P coda envelopes to varying chemical compositions and heterogeneity length scales

  5. Dynamic heterogeneity in life histories

    DEFF Research Database (Denmark)

    Tuljapurkar, Shripad; Steiner, Uli; Orzack, Steven Hecht


    generate dynamic heterogeneity: life-history differences produced by stochastic stratum dynamics. We characterize dynamic heterogeneity in a range of species across taxa by properties of the Markov chain: the entropy, which describes the extent of heterogeneity, and the subdominant eigenvalue, which...... distributions of lifetime reproductive success. Dynamic heterogeneity contrasts with fixed heterogeneity: unobserved differences that generate variation between life histories. We show by an example that observed distributions of lifetime reproductive success are often consistent with the claim that little...... or no fixed heterogeneity influences this trait. We propose that dynamic heterogeneity provides a 'neutral' model for assessing the possible role of unobserved 'quality' differences between individuals. We discuss fitness for dynamic life histories, and the implications of dynamic heterogeneity...

  6. Localization phenomena in disordered tantalum films

    Czech Academy of Sciences Publication Activity Database

    Kovaleva, Natalia; Chvostová, Dagmar; Dejneka, Alexandr


    Roč. 7, č. 7 (2017), 1-12, č. článku 257. ISSN 2075-4701 R&D Projects: GA ČR GA15-13778S Institutional support: RVO:68378271 Keywords : disordered metals * weak and Anderson localization * dc transport * spectroscopic ellipsometry Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.984, year: 2016

  7. Mixed gas plasticization phenomena in asymmetric membranes

    NARCIS (Netherlands)

    Visser, Tymen


    This thesis describes the thorough investigation of mixed gas transport behavior of asymmetric membranes in the separation of feed streams containing plasticizing gases in order to gain more insights into the complicated behavior of plasticization. To successfully employ gas separation membranes in

  8. Genetic heterogeneity of retinitis pigmentosa


    Hartono, Hartono


    Genetic heterogeneity is a phenomenon in which a genetic disease can be transmitted by several modes of inheritance. The understanding of genetic heterogeneity is important in giving genetic counselling.The presence of genetic heterogeneity can be explained by the existence of:1.different mutant alleles at a single locus, and2.mutant alleles at different loci affecting the same enzyme or protein, or affecting different enzymes or proteins.To have an overall understanding of genetic heterogene...

  9. Tumor Heterogeneity in Breast Cancer (United States)

    Turashvili, Gulisa; Brogi, Edi


    Breast cancer is a heterogeneous disease and differs greatly among different patients (intertumor heterogeneity) and even within each individual tumor (intratumor heterogeneity). Clinical and morphologic intertumor heterogeneity is reflected by staging systems and histopathologic classification of breast cancer. Heterogeneity in the expression of established prognostic and predictive biomarkers, hormone receptors, and human epidermal growth factor receptor 2 oncoprotein is the basis for targeted treatment. Molecular classifications are indicators of genetic tumor heterogeneity, which is probed with multigene assays and can lead to improved stratification into low- and high-risk groups for personalized therapy. Intratumor heterogeneity occurs at the morphologic, genomic, transcriptomic, and proteomic levels, creating diagnostic and therapeutic challenges. Understanding the molecular and cellular mechanisms of tumor heterogeneity that are relevant to the development of treatment resistance is a major area of research. Despite the improved knowledge of the complex genetic and phenotypic features underpinning tumor heterogeneity, there has been only limited advancement in diagnostic, prognostic, or predictive strategies for breast cancer. The current guidelines for reporting of biomarkers aim to maximize patient eligibility for targeted therapy, but do not take into account intratumor heterogeneity. The molecular classification of breast cancer is not implemented in routine clinical practice. Additional studies and in-depth analysis are required to understand the clinical significance of rapidly accumulating data. This review highlights inter- and intratumor heterogeneity of breast carcinoma with special emphasis on pathologic findings, and provides insights into the clinical significance of molecular and cellular mechanisms of heterogeneity. PMID:29276709

  10. Pathways toward understanding Macroscopic Quantum Phenomena (United States)

    Hu, B. L.; Subaşi, Y.


    Macroscopic quantum phenomena refer to quantum features in objects of 'large' sizes, systems with many components or degrees of freedom, organized in some ways where they can be identified as macroscopic objects. This emerging field is ushered in by several categories of definitive experiments in superconductivity, electromechanical systems, Bose-Einstein condensates and others. Yet this new field which is rich in open issues at the foundation of quantum and statistical physics remains little explored theoretically (with the important exception of the work of A J Leggett [1], while touched upon or implied by several groups of authors represented in this conference. Our attitude differs in that we believe in the full validity of quantum mechanics stretching from the testable micro to meso scales, with no need for the introduction of new laws of physics.) This talk summarizes our thoughts in attempting a systematic investigation into some key foundational issues of quantum macroscopic phenomena, with the goal of ultimately revealing or building a viable theoretical framework. Three major themes discussed in three intended essays are the large N expansion [2], the correlation hierarchy [3] and quantum entanglement [4]. We give a sketch of the first two themes and then discuss several key issues in the consideration of macro and quantum, namely, a) recognition that there exist many levels of structure in a composite body and only by judicious choice of an appropriate set of collective variables can one give the best description of the dynamics of a specific level of structure. Capturing the quantum features of a macroscopic object is greatly facilitated by the existence and functioning of these collective variables; b) quantum entanglement, an exclusively quantum feature [5], is known to persist to high temperatures [6] and large scales [7] under certain conditions, and may actually decrease with increased connectivity in a quantum network [8]. We use entanglement as a

  11. Heterogeneity in Consumer Demands and the Income Effect

    DEFF Research Database (Denmark)

    Christensen, Mette


    This paper uses unique Spanish panel data on household expenditures to test whether unobservable heterogeneity in household demands (taste, etc.) is correlated with total expenditures (income). The main finding is that tastes are indeed correlated with income for about half of the goods considered......, implying that cross-sectional estimates of income elasticities for these goods are biased. The goods are the following: food eaten outside home, alcohol and tobacco, transportation, and energy. The elasticity of alcohol and tobacco is more than halved when taking unobserved heterogeneity into account....... For transportation, the bias is sufficiently large to misclassify the good as a luxury....

  12. Can Transient Phenomena Help Improving Time Resolution in Scintillators?

    CERN Document Server

    Lecoq, P; Vasiliev, A


    The time resolution of a scintillator-based detector is directly driven by the density of photoelectrons generated in the photodetector at the detection threshold. At the scintillator level it is related to the intrinsic light yield, the pulse shape (rise time and decay time) and the light transport from the gamma-ray conversion point to the photodetector. When aiming at 10 ps time resolution, fluctuations in the thermalization and relaxation time of hot electrons and holes generated by the interaction of ionization radiation with the crystal become important. These processes last for up to a few tens of ps and are followed by a complex trapping-detrapping process, Poole-Frenkel effect, Auger ionization of traps and electron-hole recombination, which can last for a few ns with very large fluctuations. This paper will review the different processes at work and evaluate if some of the transient phenomena taking place during the fast thermalization phase can be exploited to extract a time tag with a precision in...

  13. Spatial Heterogeneity of Carbonates: genetic approach (United States)

    Violette, Sophie; Gonçalvès, Julio; de Marsily, Ghislain


    Homogeneous equivalent property is a classical concept used in hydrogeology to define heterogeneity of hydraulic properties. Known as averaging, it tries to describe the spatial variability of the rock properties from geologic observations and local measurements. The techniques available for these descriptions are mostly continuous Geostatistical models, or discontinuous facies models such as the Boolean, Indicator or Gaussian-Threshold models and the Markow chain model. These facies models are better suited to treating issues of rock strata connectivity, e.g. buried high permeability channels or low permeability barriers, which greatly affect flow and, above all, transport in aquifers. Genetic models provide new ways to incorporate more geology into the facies description, an approach that has been well developed in the oil industry, but not enough in hydrogeology. Here we present how a 3Dbasin model, based on a detailed stratigraphic data base, has been used in a genetic way to reproduce the permeability and storage coefficient heterogeneities at the regional scale.

  14. Detonation wave phenomena in bubbled liquid (United States)

    Gülhan, A.; Beylich, A. E.


    Shock wave propagation was investigated in two phase media consisting of diluted glycerin (85%) and reactive gas bubbles. To understand these complex phenomena, we first performed a numerical analysis and experimental studies of single bubbles containing a reactive gas-mixture. For the two-phase mixtures, a needle matrix bubble-generator enabled us to produce a homogeneous bubble distribution with a size dispersion less than 5%. The void fraction β0 was varied over one order of magnitude, β0=0.2-2%. It was found that there exists a critical value of shock strength above which bubble explosion starts. Once a bubble explodes, it stimulates the adjacent bubbles to explode due to emission of a blast wave; this process is followed by a series of similar events. A steady detonationlike wave propagates as a precurser with a constant velocity which is much higher than that of the first wave. To study the structure of the detonation wave the measured pressured profiles were averaged by superimposing 50 shots.

  15. Dictionary of astronomy, space, and atmospheric phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Tver, D.F.; Motz, L.; Hartmann, W.K.


    This concise and up-to-date compendium features descriptions and definitions of terms, techniques and equipment relating to celestial phenomena. It explains the latest concepts in space exploration, planetary research, stellar astronomy, and meteorological science. The authors explore the general configurations of star groups, galaxy types, stars, and other small bodies in the solar system, including such important facts as magnitude of each and distance from Earth. They describe the brightest stars one by one. Vital data provided by the Viking, Mariner, and Pioneer space probes, the Voyager flights past Jupiter and its moons, and the Apollo landings are clearly presented and explained. New concepts in stellar astronomy such as quasars, neutron stars (pulsars), and black holes are precisely defined. Also included are discussions of meteor showers and the important rock types found on each planet; definitions of meteorological terms, ad astronomical equipment including telescopes, eyepieces and their accessories, the Golay cell, canopus sensor, filar micrometer, and more. Charts aid in identifying and locating stars and planets, and helpful reference tables list the location of the major celestial bodies - asteroids, constellations, the nearest stars, the brightest stars, interesting double and variable stars and cluters. Also included is the Meisser catalog of the coordinates and magnitudes for more than 100 celestial objects.

  16. Phantom black holes and critical phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Azreg-Aïnou, Mustapha [Engineering Faculty, Başkent University, Bağlıca Campus, Ankara (Turkey); Marques, Glauber T. [Universidade Federal Rural da Amazônia ICIBE-LASIC, Av. Presidente Tancredo Neves 2501, CEP 66077-901—Belém/PA (Brazil); Rodrigues, Manuel E., E-mail:, E-mail:, E-mail: [Faculdade de Ciências Exatas e Tecnologia, Universidade Federal do Pará, Campus Universitário de Abaetetuba, CEP 68440-000, Abaetetuba, Pará (Brazil)


    We consider the two classes cosh and sinh of normal and phantom black holes of Einstein-Maxwell-dilaton theory. The thermodynamics of these holes is characterized by heat capacities that may have both signs depending on the parameters of the theory. Leaving aside the normal Reissner-Nordström black hole, it is shown that only some phantom black holes of both classes exhibit critical phenomena. The two classes share a nonextremality, but special, critical point where the transition is continuous and the heat capacity, at constant charge, changes sign with an infinite discontinuity. This point yields a classification scheme for critical points. It is concluded that the two unstable and stable phases coexist on one side of the criticality state and disappear on the other side, that is, there is no configuration where only one phase exists. The sinh class has an extremality critical point where the entropy diverges. The transition from extremality to nonextremality with the charge held constant is accompanied by a loss of mass and an increase in the temperature. A special case of this transition is when the hole is isolated (microcanonical ensemble), it will evolve by emission of energy, which results in a decrease of its mass, to the final state of minimum mass and vanishing heat capacity. The Ehrenfest scheme of classification is inaccurate in this case but the generalized one due to Hilfer leads to conclude that the transition is of order less than unity. Fluctuations near criticality are also investigated.

  17. Some novel phenomena at high density (United States)

    Berkowitz, Evan Scott

    Astrophysical environments probe matter in ways impossible on Earth. In particular, matter in compact objects are extraordinarily dense. In this thesis we discuss two phenomena that may occur at high density. First, we study toroidal topological solitons called vortons, which can occur in the kaon-condensed color-flavor-locked phase of high-density quark matter, a candidate phase for the core of some neutron stars. We show that vortons have a large radius compared to their thickness if their electrical charge is on the order of 104 times the fundamental charge. We show that shielding of electric fields by electrons dramatically reduces the size of a vorton. Second, we study an unusual phase of degenerate electrons and nonrelativistic Bose-condensed helium nuclei that may exist in helium white dwarfs. We show that this phase supports a previously-unknown gapless mode, known as the half-sound, that radically alters the material's specific heat, and can annihilate into neutrinos. We provide evidence that this neutrino radiation is negligible compared to the star's surface photoemission.

  18. Chemical Phenomena of Atomic Force Microscopy Scanning. (United States)

    Ievlev, Anton V; Brown, Chance; Burch, Matthew J; Agar, Joshua C; Velarde, Gabriel A; Martin, Lane W; Maksymovych, Petro; Kalinin, Sergei V; Ovchinnikova, Olga S


    Atomic force microscopy is widely used for nanoscale characterization of materials by scientists worldwide. The long-held belief of ambient AFM is that the tip is generally chemically inert but can be functionalized with respect to the studied sample. This implies that basic imaging and scanning procedures do not affect surface and bulk chemistry of the studied sample. However, an in-depth study of the confined chemical processes taking place at the tip-surface junction and the associated chemical changes to the material surface have been missing as of now. Here, we used a hybrid system that combines time-of-flight secondary ion mass spectrometry with an atomic force microscopy to investigate the chemical interactions that take place at the tip-surface junction. Investigations showed that even basic contact mode AFM scanning is able to modify the surface of the studied sample. In particular, we found that the silicone oils deposited from the AFM tip into the scanned regions and spread to distances exceeding 15 μm from the tip. These oils were determined to come from standard gel boxes used for the storage of the tips. The explored phenomena are important for interpreting and understanding results of AFM mechanical and electrical studies relying on the state of the tip-surface junction.

  19. Viscous theory of surface noise interaction phenomena (United States)

    Yates, J. E.


    A viscous linear surface noise interaction problem is formulated that includes noise production by an oscillating surface, turbulent or vortical interaction with a surface, and scattering of sound by a surface. The importance of viscosity in establishing uniqueness of solution and partitioning of energy into acoustic and vortical modes is discussed. The results of inviscid two dimensional airfoil theory are used to examine the interactive noise problem in the limit of high reduced frequency and small Helmholtz number. It is shown that in the case of vortex interaction with a surface, the noise produced with the full Kutta condition is 3 dB less than the no Kutta condition result. The results of a study of an airfoil oscillating in a medium at rest are discussed. It is concluded that viscosity can be a controlling factor in analyses and experiments of surface noise interaction phenomena and that the effect of edge bluntness as well as viscosity must be included in the problem formulation to correctly calculate the interactive noise.

  20. Highly energetic phenomena in water electrolysis. (United States)

    Postnikov, A V; Uvarov, I V; Lokhanin, M V; Svetovoy, V B


    Water electrolysis performed in microsystems with a fast change of voltage polarity produces optically invisible nanobubbles containing H2 and O2 gases. In this form the gases are able to the reverse reaction of water formation. Here we report extreme phenomena observed in a millimeter-sized open system. Under a frequency of driving pulses above 100 kHz the process is accompanied by clicking sounds repeated every 50 ms or so. Fast video reveals that synchronously with the click a bubble is growing between the electrodes which reaches a size of 300 μm in 50 μs. Detailed dynamics of the system is monitored by means of a vibrometer by observing a piece of silicon floating above the electrodes. The energy of a single event is estimated as 0.3 μJ and a significant part of this energy is transformed into mechanical work moving the piece. The observations are explained by the combustion of hydrogen and oxygen mixture in the initial bubble with a diameter of about 40 μm. Unusual combustion mechanism supporting spontaneous ignition at room temperature is responsible for the process. The observed effect demonstrates a principal possibility to build a microscopic internal combustion engine.