WorldWideScience

Sample records for interfacial mass transport

  1. Interfacial transport phenomena

    CERN Document Server

    Slattery, John C; Oh, Eun-Suok

    2007-01-01

    Revised and updated extensively from the previous editionDiscusses transport phenomena at common lines or three-phase lines of contactProvides a comprehensive summary about the extensions of continuum mechanics to the nanoscale.

  2. An Implementation of Interfacial Transport Equation into the CUPID code

    Energy Technology Data Exchange (ETDEWEB)

    Park, Ik Kyu; Cho, Heong Kyu; Yoon, Han Young; Jeong, Jae Jun

    2009-11-15

    A component scale thermal hydraulic analysis code, CUPID (Component Unstructured Program for Interfacial Dynamics), is being developed for the analysis of components for a nuclear reactor, such as reactor vessel, steam generator, containment, etc. It adopted a three-dimensional, transient, two phase and three-field model. In order to develop the numerical schemes for the three-field model, various numerical schemes have been examined including the SMAS, semi-implicit ICE, SIMPLE. The governing equations for a 2-phase flow are composed of mass, momentum, and energy conservation equations for each phase. These equation sets are closed by the interfacial transfer rate of mass, momentum, and energy. The interfacial transfer of mass, momentum, and energy occurs through the interfacial area, and this area plays an important role in the transfer rate. The flow regime based correlations are used for calculating the interracial area in the traditional style 2-phase flow model. This is dependent upon the flow regime and is limited to the fully developed 2-phase flow region. Its application to the multi-dimensional 2-phase flow has some limitation because it adopts the measured results of 2-phase flow in the 1-dimensional tube. The interfacial area concentration transport equation had been suggested in order to calculate the interfacial area without the interfacial area correlations. The source terms to close the interfacial area transport equation should be further developed for a wide ranger usage of it. In this study, the one group interfacial area concentration transport equation has been implemented into the CUPID code. This interfacial area concentration transport equation can be used instead of the interfacial area concentration correlations for the bubbly flow region.

  3. An Implementation of Interfacial Transport Equation into the CUPID code

    International Nuclear Information System (INIS)

    Park, Ik Kyu; Cho, Heong Kyu; Yoon, Han Young; Jeong, Jae Jun

    2009-11-01

    A component scale thermal hydraulic analysis code, CUPID (Component Unstructured Program for Interfacial Dynamics), is being developed for the analysis of components for a nuclear reactor, such as reactor vessel, steam generator, containment, etc. It adopted a three-dimensional, transient, two phase and three-field model. In order to develop the numerical schemes for the three-field model, various numerical schemes have been examined including the SMAS, semi-implicit ICE, SIMPLE. The governing equations for a 2-phase flow are composed of mass, momentum, and energy conservation equations for each phase. These equation sets are closed by the interfacial transfer rate of mass, momentum, and energy. The interfacial transfer of mass, momentum, and energy occurs through the interfacial area, and this area plays an important role in the transfer rate. The flow regime based correlations are used for calculating the interracial area in the traditional style 2-phase flow model. This is dependent upon the flow regime and is limited to the fully developed 2-phase flow region. Its application to the multi-dimensional 2-phase flow has some limitation because it adopts the measured results of 2-phase flow in the 1-dimensional tube. The interfacial area concentration transport equation had been suggested in order to calculate the interfacial area without the interfacial area correlations. The source terms to close the interfacial area transport equation should be further developed for a wide ranger usage of it. In this study, the one group interfacial area concentration transport equation has been implemented into the CUPID code. This interfacial area concentration transport equation can be used instead of the interfacial area concentration correlations for the bubbly flow region

  4. Dynamic modeling of interfacial structures via interfacial area transport equation

    International Nuclear Information System (INIS)

    Seungjin, Kim; Mamoru, Ishii

    2004-01-01

    Full text of publication follows:In the current thermal-hydraulic system analysis codes using the two-fluid model, the empirical correlations that are based on the two-phase flow regimes and regime transition criteria are being employed as closure relations for the interfacial transfer terms. Due to its inherent shortcomings, however, such static correlations are inaccurate and present serious problems in the numerical analysis. In view of this, a new dynamic approach employing the interfacial area transport equation has been studied. The interfacial area transport equation dynamically models the two-phase flow regime transitions and predicts continuous change of the interfacial area concentration along the flow field. Hence, when employed in the thermal-hydraulic system analysis codes, it eliminates artificial bifurcations stemming from the use of the static flow regime transition criteria. Therefore, the interfacial area transport equation can make a leapfrog improvement in the current capability of the two-fluid model from both scientific and practical point of view. Accounting for the substantial differences in the transport phenomena of various sizes of bubbles, the two-group interfacial area transport equations have been developed. The group 1 equation describes the transport of small-dispersed bubbles that are either distorted or spherical in shapes, and the group 2 equation describes the transport of large cap, slug or churn-turbulent bubbles. The source and sink terms in the right hand-side of the transport equations have been established by mechanistically modeling the creation and destruction of bubbles due to major bubble interaction mechanisms. The coalescence mechanisms include the random collision driven by turbulence, and the entrainment of trailing bubbles in the wake region of the preceding bubble. The disintegration mechanisms include the break-up by turbulence impact, shearing-off at the rim of large cap bubbles and the break-up of large cap

  5. Dynamic modeling of interfacial structures via interfacial area transport equation

    International Nuclear Information System (INIS)

    Seungjin, Kim; Mamoru, Ishii

    2005-01-01

    The interfacial area transport equation dynamically models the two-phase flow regime transitions and predicts continuous change of the interfacial area concentration along the flow field. Hence, when employed in the numerical thermal-hydraulic system analysis codes, it eliminates artificial bifurcations stemming from the use of the static flow regime transition criteria. Accounting for the substantial differences in the transport phenomena of various sizes of bubbles, the two-group interfacial area transport equations have been developed. The group 1 equation describes the transport of small-dispersed bubbles that are either distorted or spherical in shapes, and the group 2 equation describes the transport of large cap, slug or churn-turbulent bubbles. The source and sink terms in the right-hand-side of the transport equations have been established by mechanistically modeling the creation and destruction of bubbles due to major bubble interaction mechanisms. In the present paper, the interfacial area transport equations currently available are reviewed to address the feasibility and reliability of the model along with extensive experimental results. These include the data from adiabatic upward air-water two-phase flow in round tubes of various sizes, from a rectangular duct, and from adiabatic co-current downward air-water two-phase flow in round pipes of two sizes. (authors)

  6. Interfacial transport processes and rheology

    CERN Document Server

    Brenner, Howard

    1991-01-01

    This textbook is designed to provide the theory, methods of measurement, and principal applications of the expanding field of interfacial hydrodynamics. It is intended to serve the research needs of both academic and industrial scientists, including chemical or mechanical engineers, material and surface scientists, physical chemists, chemical and biophysicists, rheologists, physiochemical hydrodynamicists, and applied mathematicians (especially those with interests in viscous fluid mechanics and continuum mechanics).As a textbook it provides materials for a one- or two-semester graduate-level

  7. Interfacial Water-Transport Effects in Proton-Exchange Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Kienitz, Brian; Yamada, Haruhiko; Nonoyama, Nobuaki; Weber, Adam

    2009-11-19

    It is well known that the proton-exchange membrane is perhaps the most critical component of a polymer-electrolyte fuel cell. Typical membranes, such as Nafion(R), require hydration to conduct efficiently and are instrumental in cell water management. Recently, evidence has been shown that these membranes might have different interfacial morphology and transport properties than in the bulk. In this paper, experimental data combined with theoretical simulations will be presented that explore the existence and impact of interfacial resistance on water transport for Nafion(R) 21x membranes. A mass-transfer coefficient for the interfacial resistance is calculated from experimental data using different permeation cells. This coefficient is shown to depend exponentially on relative humidity or water activity. The interfacial resistance does not seem to exist for liquid/membrane or membrane/membrane interfaces. The effect of the interfacial resistance is to flatten the water-content profiles within the membrane during operation. Under typical operating conditions, the resistance is on par with the water-transport resistance of the bulk membrane. Thus, the interfacial resistance can be dominant especially in thin, dry membranes and can affect overall fuel-cell performance.

  8. Development of interfacial area transport equation

    International Nuclear Information System (INIS)

    Kim, Seung Jin; Ishii, Mamoru; Kelly, Joseph

    2005-01-01

    The interfacial area transport equation dynamically models the changes in interfacial structures along the flow field by mechanistically modeling the creation and destruction of dispersed phase. Hence, when employed in the numerical thermal-hydraulic system analysis codes, it eliminates artificial bifurcations stemming from the use of the static flow regime transition criteria. Accounting for the substantial differences in the transport mechanism for various sizes of bubbles, the transport equation is formulated for two characteristic groups of bubbles. The group 1 equation describes the transport of small-dispersed bubbles, whereas the group 2 equation describes the transport of large cap, slug or churn-turbulent bubbles. To evaluate the feasibility and reliability of interfacial area transport equation available at present, it is benchmarked by an extensive database established in various two-phase flow configurations spanning from bubbly to churn-turbulent flow regimes. The geometrical effect in interfacial area transport is examined by the data acquired in vertical air-water two-phase flow through round pipes of various sizes and a confined flow duct, and by those acquired in vertical co-current downward air-water two-phase flow through round pipes of two different sizes

  9. Interfacial Thermal Transport via One-Dimensional Atomic Junction Model

    Directory of Open Access Journals (Sweden)

    Guohuan Xiong

    2018-03-01

    Full Text Available In modern information technology, as integration density increases rapidly and the dimension of materials reduces to nanoscale, interfacial thermal transport (ITT has attracted widespread attention of scientists. This review introduces the latest theoretical development in ITT through one-dimensional (1D atomic junction model to address the thermal transport across an interface. With full consideration of the atomic structures in interfaces, people can apply the 1D atomic junction model to investigate many properties of ITT, such as interfacial (Kapitza resistance, nonlinear interface, interfacial rectification, and phonon interference, and so on. For the ballistic ITT, both the scattering boundary method (SBM and the non-equilibrium Green’s function (NEGF method can be applied, which are exact since atomic details of actual interfaces are considered. For interfacial coupling case, explicit analytical expression of transmission coefficient can be obtained and it is found that the thermal conductance maximizes at certain interfacial coupling (harmonic mean of the spring constants of the two leads and the transmission coefficient is not a monotonic decreasing function of phonon frequency. With nonlinear interaction—phonon–phonon interaction or electron–phonon interaction at interface, the NEGF method provides an efficient way to study the ITT. It is found that at weak linear interfacial coupling, the nonlinearity can improve the ITT, but it depresses the ITT in the case of strong-linear coupling. In addition, the nonlinear interfacial coupling can induce thermal rectification effect. For interfacial materials case which can be simulated by a two-junction atomic chain, phonons show interference effect, and an optimized thermal coupler can be obtained by tuning its spring constant and atomic mass.

  10. Interfacial stability with mass and heat transfer

    International Nuclear Information System (INIS)

    Hsieh, D.Y.

    1977-07-01

    A simplified formulation is presented to deal with interfacial stability problems with mass and heat transfer. For Rayleigh-Taylor stability problems of a liquid-vapor system, it was found that the effect of mass and heat transfer tends to enhance the stability of the system when the vapor is hotter than the liquid, although the classical stability criterion is still valid. For Kelvin-Holmholtz stability problems, however, the classical stability criterion was found to be modified substantially due to the effect of mass and heat transfer

  11. Modeling interfacial area transport in multi-fluid systems

    Energy Technology Data Exchange (ETDEWEB)

    Yarbro, Stephen Lee [Univ. of California, Berkeley, CA (United States)

    1996-11-01

    Many typical chemical engineering operations are multi-fluid systems. They are carried out in distillation columns (vapor/liquid), liquid-liquid contactors (liquid/liquid) and other similar devices. An important parameter is interfacial area concentration, which determines the rate of interfluid heat, mass and momentum transfer and ultimately, the overall performance of the equipment. In many cases, the models for determining interfacial area concentration are empirical and can only describe the cases for which there is experimental data. In an effort to understand multiphase reactors and the mixing process better, a multi-fluid model has been developed as part of a research effort to calculate interfacial area transport in several different types of in-line static mixers. For this work, the ensemble-averaged property conservation equations have been derived for each fluid and for the mixture. These equations were then combined to derive a transport equation for the interfacial area concentration. The final, one-dimensional model was compared to interfacial area concentration data from two sizes of Kenics in-line mixer, two sizes of concurrent jet and a Tee mixer. In all cases, the calculated and experimental data compared well with the highest scatter being with the Tee mixer comparison.

  12. Interfacial structures - Thermodynamical and experimental studies of the interfacial mass transfer

    International Nuclear Information System (INIS)

    Morel, Jean-Emile

    1972-01-01

    In the first section, we put forward hypotheses concerning the structure of the interfacial regions between two immiscible liquid phases. It appears that the longitudinal structure is comparable with that of a crystallized solid and that the transversal structure is nearest of that of a liquid. In the second section, we present a thermodynamical treatment of the irreversible phenomena in the interfacial region. The equation of evolution of a system consisting of two immiscible liquid phases are deduced. The third part allows an experimental verification of the theoretical relations. We also make clear, in certain cases, the appearance of a great 'interfacial resistance' which slows down the interfacial mass transfer. (author) [fr

  13. Interfacial and Wall Transport Models for SPACE-CAP Code

    International Nuclear Information System (INIS)

    Hong, Soon Joon; Choo, Yeon Joon; Han, Tae Young; Hwang, Su Hyun; Lee, Byung Chul; Choi, Hoon; Ha, Sang Jun

    2009-01-01

    The development project for the domestic design code was launched to be used for the safety and performance analysis of pressurized light water reactors. And CAP (Containment Analysis Package) code has been also developed for the containment safety and performance analysis side by side with SPACE. The CAP code treats three fields (gas, continuous liquid, and dispersed drop) for the assessment of containment specific phenomena, and is featured by its multidimensional assessment capabilities. Thermal hydraulics solver was already developed and now under testing of its stability and soundness. As a next step, interfacial and wall transport models was setup. In order to develop the best model and correlation package for the CAP code, various models currently used in major containment analysis codes, which are GOTHIC, CONTAIN2.0, and CONTEMPT-LT, have been reviewed. The origins of the selected models used in these codes have also been examined to find out if the models have not conflict with a proprietary right. In addition, a literature survey of the recent studies has been performed in order to incorporate the better models for the CAP code. The models and correlations of SPACE were also reviewed. CAP models and correlations are composed of interfacial heat/mass, and momentum transport models, and wall heat/mass, and momentum transport models. This paper discusses on those transport models in the CAP code

  14. Interfacial and Wall Transport Models for SPACE-CAP Code

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Soon Joon; Choo, Yeon Joon; Han, Tae Young; Hwang, Su Hyun; Lee, Byung Chul [FNC Tech., Seoul (Korea, Republic of); Choi, Hoon; Ha, Sang Jun [Korea Electric Power Research Institute, Daejeon (Korea, Republic of)

    2009-10-15

    The development project for the domestic design code was launched to be used for the safety and performance analysis of pressurized light water reactors. And CAP (Containment Analysis Package) code has been also developed for the containment safety and performance analysis side by side with SPACE. The CAP code treats three fields (gas, continuous liquid, and dispersed drop) for the assessment of containment specific phenomena, and is featured by its multidimensional assessment capabilities. Thermal hydraulics solver was already developed and now under testing of its stability and soundness. As a next step, interfacial and wall transport models was setup. In order to develop the best model and correlation package for the CAP code, various models currently used in major containment analysis codes, which are GOTHIC, CONTAIN2.0, and CONTEMPT-LT, have been reviewed. The origins of the selected models used in these codes have also been examined to find out if the models have not conflict with a proprietary right. In addition, a literature survey of the recent studies has been performed in order to incorporate the better models for the CAP code. The models and correlations of SPACE were also reviewed. CAP models and correlations are composed of interfacial heat/mass, and momentum transport models, and wall heat/mass, and momentum transport models. This paper discusses on those transport models in the CAP code.

  15. Uncertainty analysis of an interfacial area reconstruction algorithm and its application to two group interfacial area transport equation validation

    International Nuclear Information System (INIS)

    Dave, A.J.; Manera, A.; Beyer, M.; Lucas, D.; Prasser, H.-M.

    2016-01-01

    Wire mesh sensors (WMS) are state of the art devices that allow high resolution (in space and time) measurement of 2D void fraction distribution over a wide range of two-phase flow regimes, from bubbly to annular. Data using WMS have been recorded at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) (Lucas et al., 2010; Beyer et al., 2008; Prasser et al., 2003) for a wide combination of superficial gas and liquid velocities, providing an excellent database for advances in two-phase flow modeling. In two-phase flow, the interfacial area plays an integral role in coupling the mass, momentum and energy transport equations of the liquid and gas phase. While current models used in best-estimate thermal-hydraulic codes (e.g. RELAP5, TRACE, TRACG, etc.) are still based on algebraic correlations for the estimation of the interfacial area in different flow regimes, interfacial area transport equations (IATE) have been proposed to predict the dynamic propagation in space and time of interfacial area (Ishii and Hibiki, 2010). IATE models are still under development and the HZDR WMS experimental data provide an excellent basis for the validation and further advance of these models. The current paper is focused on the uncertainty analysis of algorithms used to reconstruct interfacial area densities from the void-fraction voxel data measured using WMS and their application towards validation efforts of two-group IATE models. In previous research efforts, a surface triangularization algorithm has been developed in order to estimate the surface area of individual bubbles recorded with the WMS, and estimate the interfacial area in the given flow condition. In the present paper, synthetically generated bubbles are used to assess the algorithm’s accuracy. As the interfacial area of the synthetic bubbles are defined by user inputs, the error introduced by the algorithm can be quantitatively obtained. The accuracy of interfacial area measurements is characterized for different bubbles

  16. Uncertainty analysis of an interfacial area reconstruction algorithm and its application to two group interfacial area transport equation validation

    Energy Technology Data Exchange (ETDEWEB)

    Dave, A.J., E-mail: akshayjd@umich.edu [Department of Nuclear Engineering and Rad. Sciences, University of Michigan, Ann Arbor, MI 48105 (United States); Manera, A. [Department of Nuclear Engineering and Rad. Sciences, University of Michigan, Ann Arbor, MI 48105 (United States); Beyer, M.; Lucas, D. [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Fluid Dynamics, 01314 Dresden (Germany); Prasser, H.-M. [Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich (Switzerland)

    2016-12-15

    Wire mesh sensors (WMS) are state of the art devices that allow high resolution (in space and time) measurement of 2D void fraction distribution over a wide range of two-phase flow regimes, from bubbly to annular. Data using WMS have been recorded at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) (Lucas et al., 2010; Beyer et al., 2008; Prasser et al., 2003) for a wide combination of superficial gas and liquid velocities, providing an excellent database for advances in two-phase flow modeling. In two-phase flow, the interfacial area plays an integral role in coupling the mass, momentum and energy transport equations of the liquid and gas phase. While current models used in best-estimate thermal-hydraulic codes (e.g. RELAP5, TRACE, TRACG, etc.) are still based on algebraic correlations for the estimation of the interfacial area in different flow regimes, interfacial area transport equations (IATE) have been proposed to predict the dynamic propagation in space and time of interfacial area (Ishii and Hibiki, 2010). IATE models are still under development and the HZDR WMS experimental data provide an excellent basis for the validation and further advance of these models. The current paper is focused on the uncertainty analysis of algorithms used to reconstruct interfacial area densities from the void-fraction voxel data measured using WMS and their application towards validation efforts of two-group IATE models. In previous research efforts, a surface triangularization algorithm has been developed in order to estimate the surface area of individual bubbles recorded with the WMS, and estimate the interfacial area in the given flow condition. In the present paper, synthetically generated bubbles are used to assess the algorithm’s accuracy. As the interfacial area of the synthetic bubbles are defined by user inputs, the error introduced by the algorithm can be quantitatively obtained. The accuracy of interfacial area measurements is characterized for different bubbles

  17. Molecular Level Manipulation of Interfacial Charge Transport

    Science.gov (United States)

    Song, Charles Kiseok

    The bulk-heterojunction organic (BHJ) photovoltaics (OPVs) and lithium ion battery (LiB) have been extensively studied. Power conversion efficiency (PCE) of an OPV greater than 10% and utilizing group 4 elements as the anode to accommodate high capacity for LiBs are the goals of many studies. However, the currently ubiquitous hole-collecting layer of OPVs limit device performance and durability, and group 4 elements are unstable and brittle to be commercially produced. Thus, my thesis has focused on developing functional and durable interfacial layers (IFLs) for OPVs and characterizing flexible artificial solid-electrolyte interphase (SEI) for LiBs. In Chapter 2, a series of robust organosilane-based dipolar self-assembled monolayer (SAM) IFLs on the tin-doped indium oxide (ITO) anodes of OPVs are developed. These hydrophobic and amorphous IFLs modify anode work functions from 4.66 to 5.27 eV. Two series of Glass/ITO/SAM IFL/Active Layer/LiF/Al BHJ OPVs are fabricated, and a strong positive correlation between the electrochemically-derived heterogeneous electron transport rate constants (ks) and OPV PCEs are observed due to enhanced anode carrier extraction. In Chapter 3, a series of unusually denser organosilane-based SAM IFLs on ITO anodes of OPVs are developed. Precursor mixtures having short and long tail groups were simultaneously deposited to minimize sterical encumbrance and denser SAM IFLs are achieved. These heterogeneous supersaturated SAMs (SHSAMs), with PCE (7.62%) exceeding that of PEDOT:PSS IFL, are found to be 17% denser and enhances PCE by 54% versus comparable devices with homogeneous SAM IFLs due to enhanced charge selectivity and collection. In Chapter 4, libraries of electron affinities (EAs) of widely used conductive polymers are constructed by cyclic voltammetry (CV) in conventional and LiB media. The EAs of the conductive polymer films measured via CV in conventional (EAC) and Li+ battery (EAB) media could be linearly correlated by EAB = (1

  18. Interfacial area transport in a confined Bubbly flow

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S.; Sun, X.; Ishii, M. [Purdue Univ., Lafayette, IN (United States). School of Nuclear Engineering; Lincoln, F. [Bettis Atomic Power Lab., West Mifflin, Bechtel Bettis, Inc., PA (United States)

    2001-07-01

    The interfacial area transport equation applicable to the bubbly flow is presented. The model is evaluated against the data acquired in an adiabatic air-water upward two-phase flow loop with a test section of 20 cm in width and 1 cm in gap. In general, a good agreement, within the measurement error of {+-}10%, is observed for a wide range in the bubbly flow regime. The sensitivity analysis on the individual particle interaction mechanisms demonstrates the active interactions between the bubbles and highlights the mechanisms playing the dominant role in interfacial area transport. (author)

  19. Interfacial fluid dynamics and transport processes

    CERN Document Server

    Schwabe, Dietrich

    2003-01-01

    The present set of lectures and tutorial reviews deals with various topical aspects related to instabilities of interfacial processes and driven flows from both the theoretical and experimental point of views. New research has been spurred by the many demands for applications in material sciences (melting, solidification, electro deposition), biomedical engineering and processing in microgravity environments. This book is intended as both a modern source of reference for researchers in the field as well as an introduction to postgraduate students and non-specialists from related areas.

  20. Probing Interfacial Processes on Graphene Surface by Mass Detection

    Science.gov (United States)

    Kakenov, Nurbek; Kocabas, Coskun

    2013-03-01

    In this work we studied the mass density of graphene, probed interfacial processes on graphene surface and examined the formation of graphene oxide by mass detection. The graphene layers were synthesized by chemical vapor deposition method on copper foils and transfer-printed on a quartz crystal microbalance (QCM). The mass density of single layer graphene was measured by investigating the mechanical resonance of the QCM. Moreover, we extended the developed technique to probe the binding dynamics of proteins on the surface of graphene, were able to obtain nonspecific binding constant of BSA protein of graphene surface in aqueous solution. The time trace of resonance signal showed that the BSA molecules rapidly saturated by filling the available binding sites on graphene surface. Furthermore, we monitored oxidation of graphene surface under oxygen plasma by tracing the changes of interfacial mass of the graphene controlled by the shifts in Raman spectra. Three regimes were observed the formation of graphene oxide which increases the interfacial mass, the release of carbon dioxide and the removal of small graphene/graphene oxide flakes. Scientific and Technological Research Council of Turkey (TUBITAK) grant no. 110T304, 109T209, Marie Curie International Reintegration Grant (IRG) grant no 256458, Turkish Academy of Science (TUBA-Gebip).

  1. Basic equations of interfacial area transport in gas-liquid two-phase flow

    International Nuclear Information System (INIS)

    Kataoka, I.; Yoshida, K.; Naitoh, M.; Okada, H.; Morii, T.

    2011-01-01

    The rigorous and consistent formulations of basic equations of interfacial area transport were derived using correlation functions of characteristic function of each phase and velocities of each phase. Turbulent transport term of interfacial area concentration was consistently derived and related to the difference between interfacial velocity and averaged velocity of each phase. Constitutive equations of turbulent transport terms of interfacial area concentration were proposed for bubbly flow. New transport model and constitutive equations were developed for churn flow. These models and constitutive equations are validated by experimental data of radial distributions of interfacial area concentration in bubbly and churn flow. (author)

  2. Impact of Interfacial Water Transport in PEMFCs on Cell Performance

    International Nuclear Information System (INIS)

    Kotaka, Toshikazu; Tabuchi, Yuichiro; Pasaogullari, Ugur; Wang, Chao-Yang

    2014-01-01

    Coupled cell performance evaluation, liquid water visualization by neutron radiography (NRG) and numerical modeling based on multiphase mixture (M2) model were performed with three types of GDMs: Micro Porous Layer (MPL) free; Carbon Paper (CP) with MPL; and CP free to investigate interfacial liquid water transport phenomena in PEMFCs and its effect on cell performance. The visualized results of MPL free GDM with different wettability of bi-polar plates (BPPs) showed hydrophilic BPP improved liquid water transport at the interface between CP and channel. Numerical modeling results indicated that this difference with BPP wettability was caused by the liquid water coverage difference on CP surface. Thus, controlling liquid water coverage is the one of the key strategies for improving cell performance. Additionally, liquid water distributions across the cell for three types of GDMs were compared and significant difference in liquid water content at the interface between Catalyst Layer (CL) and GDM was observed. Numerical modeling suggests this difference is influenced by the gap at the interface and that the MPL could minimize this effect. The CP free cell (i.e. only MPL) showed the best performance and the lowest liquid water content. There were multiple impacts of interfacial liquid water transport both at CL-GDM and GDM-channel interfaces. High hydrophobicity and fine structure of MPLs contributed to enhanced liquid water transport at GDM-channel interface and as a result reduced the liquid water coverage. At the same time, MPL improves contact at the CL-GDM interface in the same manner as seen in CP with MPL case. Thus, the CP free concept showed the best performance. It is suggested that the design of the interface between each component of the PEMFC has a great impact on cell performance and plays a significant role in achievement of high current density operation and cost reduction in FCEVs

  3. Interfacial structures and area transport in upward and downward two-phase flow

    International Nuclear Information System (INIS)

    Paranjape, S. S.; Kim, S.; Ishii, M.; Kelly, J.

    2003-01-01

    An experimental study has been carried out for upward and downward two-phase flow to study local interfacial structures and interfacial area transport. The flow studied, is an adiabatic, air-water, co-current, two-phase flow, in 25.4 mm and 50.8 mm ID test sections. Flow regime map is obtained using the characteristic signals obtained from an impedance void meter, employing neural network based identification methodology. A four sensor conductivity probe is used to measure the local two phase flow parameters, in bubbly flow regime. The local profiles of these parameters as well as their axial development reveal the nature of the interfacial structures and the bubble interaction mechanisms occurring in the flow. Furthermore, this study provides a good database for the development of the interfacial area transport equation, which dynamically models the changes in the interfacial area along a flow field. An interfacial area transport equation is used for downward flow based on that developed for the upward flow, with certain modifications in the bubble interaction terms. The area averaged values of the interfacial area concentration are compared with those predicted by the interfacial area transport model. The differences in the interfacial structures and interfacial area transport in co-current downward and upward two-phase flows are studied

  4. Fundamental study on interfacial area transport model (I) (contract research)

    International Nuclear Information System (INIS)

    Mishima, Kaichiro; Nakamura, Hideo

    2001-03-01

    Recently, improvement in the best-estimate (BE) code predictive capability is attempted by incorporating the interfacial area transport model (IATM) into a one-dimensional two-fluid model to represent gas-liquid two-phase flows in detail with less uncertainty in the flow predictions. Internationally, the nuclear regulatory commission (NRC) and Purdue University in the U.S.A. and CEA in France have promoted the renewal of their BE codes such as TRAC, RELAP5 and CATHARE, by introducing the IATM in cooperative manner. In Japan, JAERI is underway to develop a one-dimensional code based primarily on the IATM against the licensing procedures of next-generation nuclear reactors. The IATM has a possibility to correctly predict flow transient along flow path for such flows as developing flows, multi-dimensional flows, transitional flows, boiling flows, which are difficult to accurately predict by the two-fluid models employed in the current BE codes. The newly developed code with the IATM would dramatically improve the accuracy in the flow prediction. The model, however, is under development and needs great effort to overcome many difficulties with plenty of theoretical considerations based on much of data bases to be acquired further. This study attempts to measure interfacial area in air-water two-phase flows in a large-diameter tube to understand the characteristic of multi-dimensional flows that usually appear in large-diameter tube flows, and provide data bases, to contribute the development of the IATM. The results obtained by such institutes as Purdue University and CEA France were reviewed first. Clarified are the current status and problems of the IATM, basics and practical methods to measure the interfacial area using multi-sensor miniature local probes; metal needle electro-resistance probe and fiber-optic probe. It was found that the applicability of the IATM is limited mostly to a one-dimensional bubbly flow, and is far from satisfactory for multi

  5. Interfacial Properties of Methylcelluloses: The Influence of Molar Mass

    Directory of Open Access Journals (Sweden)

    Pauline L. Nasatto

    2014-12-01

    Full Text Available The interfacial interactions of four methylcelluloses having the same average degree of substitution and distribution of methyl groups, but different molar masses, are studied at ambient temperature and at very low polymer concentrations. Firstly, the surface tension σ at the water/air interface is determined for the progressive addition of methylcellulose up to 100 mg/L; σ starts to decrease over 1 mg/L up to the critical aggregation concentration (CAC at 10 mg/L. The curves describing the influence of polymer concentration on σ are independent of the molar mass at equilibrium. Secondly, the adsorption of methylcellulose on silica particles is estimated from ζ-potential measurements. The data are interpreted in terms of an increase of the adsorbed layer thickness at the interface when the molar mass of methylcellulose increases. It is concluded that methylcellulose is adsorbed, forming trains and loops at the interface based on the equilibrium between surface free energy and solvent quality.

  6. Interfacial area transport of bubbly flow in a small diameter pipe

    International Nuclear Information System (INIS)

    Hibiki, Takashi; Takamasa, Tomoji; Ishii, Mamoru

    2001-01-01

    In relation to the development of the interfacial area transport equation, this study focused on modeling of the interfacial area transport mechanism of vertical adiabatic air-water bubbly flows in a relatively small diameter pipe where the bubble size-to-pipe diameter ratio was relatively high and the radial motion of bubbles was restricted by the presence of the pipe wall. The sink term of the interfacial area concentration was modeled by considering wake entrainment as a possible bubble coalescence mechanism, whereas the source term was neglected by assuming negligibly small bubble breakup for low liquid velocity conditions based on visual observation. One-dimensional interfacial area transport equation with the derived sink term was evaluated by using five datasets of vertical adiabatic air-water bubbly flows measured in a 9.0 mm-diameter pipe (superficial gas velocity: 0.013-0.052 m/s, superficial liquid velocity: 0.58-1.0 m/s). The modeled interfacial area transport equation could reproduce the proper trend of the axial interfacial area transport and predict the measured interfacial area concentrations within an average relative deviation of ±11.1%. It was recognized that the present model would be promising for predicting the interfacial area transport of the examined bubbly flows. (author)

  7. Interfacial transport characteristics in a gas-liquid or an immiscible liquid-liquid stratified flow

    International Nuclear Information System (INIS)

    Inoue, A.; Aoki, S.; Aritomi, M.; Kozawa, Y.

    1982-01-01

    This paper is a review for an interfacial transport characteristics of mass, momentum and energy in a gas-liquid or a immiscible liquid-liquid stratified flow with wavy interface which have been studied in our division. In the experiment, a characteristic of wave motion and its effect to the turbulence near the interface as well as overall flow characteristics like pressure drop, position of the interface were investigated in an air-water, an air-mercury and a water-liquid metal stratified flow. On the other hand, several models based on the mixing length model and a two-equation model of turbulence, with special interfacial boundary conditions in which the wavy surface was regarded as a rough surface correspond to the wavy height, a source of turbulent energy equal to the wave energy and a damped-turbulence due to the surface tension, were proposed to predict the flow characteristics and the interfacial heat transfer in a fully developed and an undeveloped stratified flow and examined by the experimental data. (author)

  8. Mass Transport within Soils

    Energy Technology Data Exchange (ETDEWEB)

    McKone, Thomas E.

    2009-03-01

    Contaminants in soil can impact human health and the environment through a complex web of interactions. Soils exist where the atmosphere, hydrosphere, geosphere, and biosphere converge. Soil is the thin outer zone of the earth's crust that supports rooted plants and is the product of climate and living organisms acting on rock. A true soil is a mixture of air, water, mineral, and organic components. The relative proportions of these components determine the value of the soil for agricultural and for other human uses. These proportions also determine, to a large extent, how a substance added to soil is transported and/or transformed within the soil (Spositio, 2004). In mass-balance models, soil compartments play a major role, functioning both as reservoirs and as the principal media for transport among air, vegetation, surface water, deeper soil, and ground water (Mackay, 2001). Quantifying the mass transport of chemicals within soil and between soil and atmosphere is important for understanding the role soil plays in controlling fate, transport, and exposure to multimedia pollutants. Soils are characteristically heterogeneous. A trench dug into soil typically reveals several horizontal layers having different colors and textures. As illustrated in Figure 1, these multiple layers are often divided into three major horizons: (1) the A horizon, which encompasses the root zone and contains a high concentration of organic matter; (2) the B horizon, which is unsaturated, lies below the roots of most plants, and contains a much lower organic carbon content; and (3) the C horizon, which is the unsaturated zone of weathered parent rock consisting of bedrock, alluvial material, glacial material, and/or soil of an earlier geological period. Below these three horizons lies the saturated zone - a zone that encompasses the area below ground surface in which all interconnected openings within the geologic media are completely filled with water. Similarly to the unsaturated

  9. Experimental study on interfacial area transport in downward two-phase flow

    Science.gov (United States)

    Wang, Guanyi

    In view of the importance of two group interfacial area transport equations and lack of corresponding accurate downward flow database that can reveal two group interfacial area transport, a systematic database for adiabatic, air-water, vertically downward two-phase flow in a round pipe with inner diameter of 25.4 mm was collected to gain an insight of interfacial structure and provide benchmarking data for two-group interfacial area transport models. A four-sensor conductivity probe was used to measure the local two phase flow parameters and data was collected with data sampling frequency much higher than conventional data sampling frequency to ensure the accuracy. Axial development of local flow parameter profiles including void fraction, interfacial area concentration, and Sauter mean diameter were presented. Drastic inter-group transfer of void fraction and interfacial area was observed at bubbly to slug transition flow. And the wall peaked interfacial area concentration profiles were observed in churn-turbulent flow. The importance of local data about these phenomenon on flow structure prediction and interfacial area transport equation benchmark was analyzed. Bedsides, in order to investigate the effect of inlet conditions, all experiments were repeated after installing the flow straightening facility, and the results were briefly analyzed. In order to check the accuracy of current data, the experiment results were cross-checked with rotameter measurement as well as drift-flux model prediction, the averaged error is less than 15%. Current models for two-group interfacial area transport equation were evaluated using these data. The results show that two-group interfacial area transport equations with current models can predict most flow conditions with error less than 20%, except some bubbly to slug transition flow conditions and some churn-turbulent flow conditions. The disagreement between models and experiments could result from underestimate of inter

  10. Interfacial and transport properties of nanoconstrained inorganic and organic materials

    Science.gov (United States)

    Kocherlakota, Lakshmi Suhasini

    Nanoscale constraints impact the material properties of both organic and inorganic systems. The systems specifically studied here are (i) nanoconstrained polymeric systems, poly(l-trimethylsilyl-1-propyne) (PTMSP) and poly(ethylene oxide) (PEO) relevant to gas separation membranes (ii) Zwitterionic polymers poly(sulfobetaine methacrylate)(pSBMA), poly(carboxybetaine acrylamide) (pCBAA), and poly(oligo(ethylene glycol) methyl methacrylate) (PEGMA) brushes critical for reducing bio-fouling (iii) Surface properties of N-layer graphene sheets. Interfacial constraints in ultrathin poly(l-trimethylsilyl-1-propyne) (PTMSP) membranes yielded gas permeabilities and CO2/helium selectivities that exceed bulk PTMSP membrane transport properties by up to three-fold for membranes of submicrometer thickness. Indicative of a free volume increase, a molecular energetic mobility analysis (involving intrinsic friction analysis) revealed enhanced methyl side group mobilities in thin PTMSP membranes with maximum permeation, compared to bulk films. Aging studies conducted over the timescales relevant to the conducted experiments signify that the free volume states in the thin film membranes are highly unstable in the presence of sorbing gases such as CO2. To maintain this high free volume configuration of polymer while improving the temporal stability an "inverse" architecture to conventional polymer nanocomposites was investigated, in which the polymer phase of PTMSP and PEO were interfacially and dimensionally constrained in nanoporous anodic aluminum oxide (AAO) membranes. While with this architecture the benefits of nanocomposite and ultrathin film membranes of PTMSP could be reproduced and improved upon, also the temporal stability could be enhanced substantially. The PEO-AAO nanocomposite membranes also revealed improved gas selectivity properties of CO2 over helium. In the thermal transition studies of zwitterionic pSBMA brushes a reversible critical transition temperature of 60

  11. Interfacial transport phenomena and stability in liquid-metal/water systems: scaling considerations

    International Nuclear Information System (INIS)

    Abdulla, S.; Liu, X.; Anderson, M.; Bonazza, R.; Corradini, M.; Cho, D.

    2001-01-01

    One concept being considered for steam generation in innovative nuclear reactor applications, involves water coming into direct contact with a circulating molten metal. The vigorous agitation of the two fluids, the direct liquid-liquid contact and the consequent large interfacial area give rise to very high heat transfer coefficients and rapid steam generation. For an optimum design of such direct contact heat exchange and vaporization systems, detailed knowledge is necessary of the various flow regimes, interfacial transport phenomena, heat transfer and operational stability. In this paper we describe current results from the first year of this research that studies the transport phenomena involved with the injection of water into molten metals (e.g., lead alloys). In particular, this work discusses scaling considerations related to direct contact heat exchange, our experimental plans for investigation and a test plan for the important experimental parameters; i.e., the water and liquid metal mass flow rates, the liquid metal pool temperature and the ambient pressure of the direct contact heat exchanger. Past experimental work and initial scaling results suggest that our experiments can directly represent the proper liquid metal pool temperature and the water subcooling. The experimental variation in water and liquid metal flow rates and system pressure (1-10 bar), although smaller than the current conceptual system designs, is sufficient to verify the expected scale effects to demonstrate the phenomena. (authors)

  12. Mass transport by groundwater

    International Nuclear Information System (INIS)

    Ledoux, E.; Goblet, P.; Jamet, Ph.; De Marsily, G.; Des Orres, P.E.; Lewi, J.

    1991-01-01

    The first analyses of the safety of radioactive waste disposal published in 1970s were mostly of a generic type using the models of radionuclide migration in the geosphere. These simply constructed models gave way to more sophisticated techniques in order to represent better the complexity and diversity of geological media. In this article, it is attempted to review the various concepts used to quantify radionuclide migration and the evolution of their incorporation into the models. First, it was examined how the type of discontinuity occurring in geological media affects the choice of a representative model. The principle of transport in the subsurface was reviewed, and the effect that coupled processes exert to groundwater flow and mass migration was discussed. The processes that act directly to cause groundwater flow were distinguished. The method of validating such models by comparing the results with the geochemical systems in nature was explained. (K.I.)

  13. Interfacial area transport of subcooled boiling flow in a vertical annulus

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, Caleb S.; Ozar, Basar; Hibiki, Takashi; Ishii, Mamoru, E-mail: ishii@purdue.edu

    2014-03-15

    Highlights: • Discussion of boiling and wall nucleation dataset obtained in a vertical annulus. • Overview of the interfacial area transport equation modeling in boiling flow. • Comparison of bubble departure diameter and frequency with existing models. • Evaluation of the interfacial area transport equation prediction in boiling flow. - Abstract: In an effort to improve the prediction of void fraction and heat transfer characteristics in two-phase systems, the two-group interfacial area transport equation has been developed for use with the two-group two-fluid model. The two-group approach treats spherical/distorted bubbles as Group-1 and cap/slug/churn-turbulent bubbles as Group-2. Therefore, the interfacial area transport of steam-water two-phase flow in a vertical annulus has been investigated experimentally, including bulk flow parameters and wall nucleation characteristics. The theoretical modeling of interfacial area transport equation with phase change terms is introduced and discussed along with the experimental results. Benchmark of the interfacial area transport equation is performed considering the effects of bubble interaction mechanisms such as bubble break-up and coalescence, as well as, effects of phase change mechanisms such as wall nucleation and condensation for subcooled boiling. From the benchmark, sensitivity in the constitutive relations for Group-1 phase change mechanisms, such as wall nucleation and condensation is clear. The Group-2 interfacial area transport is shown to be dominated by the interfacial heat transfer mechanism causing expansion of Group-1 bubbles into Group-2 bubbles in the boiling flow.

  14. Interfacial Healing and Transport Phenomena Modeling ff Biopolymers

    Science.gov (United States)

    Lebron, Karla

    This research focuses on the characterization of bioplastics joined using ultrasonic welding and modeling of temperature distributions and interfacial healing. Polylactic acid (PLA), which is typically derived from starch-rich crops such as corn, was studied. While the measurement of activation energy for interfacial healing at weld interfaces of PLA films has been reported, here, this information is used to predict the weld strength of rigid PLA samples welded by ultrasonics. A characterization of the mechanical properties was completed with a tensile test to determine the effects of amplitude, melt velocity and collapse distance on weld strength. From previous interfacial healing activation energy measurements based on an impulse welding method, it was also possible to predict weld strength. It was found that the most influential parameters were weld time, collapse distance and weld velocity. In general, the model predicted weld strength reasonably well with r2 values between 0.77 and 0.78.

  15. Two-group modeling of interfacial area transport in large diameter channels

    Energy Technology Data Exchange (ETDEWEB)

    Schlegel, J.P., E-mail: schlegelj@mst.edu [Department of Mining and Nuclear Engineering, Missouri University of Science and Technology, 301 W 14th St., Rolla, MO 65409 (United States); Hibiki, T.; Ishii, M. [School of Nuclear Engineering, Purdue University, 400 Central Dr., West Lafayette, IN 47907 (United States)

    2015-11-15

    Highlights: • Implemented updated constitutive models and benchmarking method for IATE in large pipes. • New model and method with new data improved the overall IATE prediction for large pipes. • Not all conditions well predicted shows that further development is still required. - Abstract: A comparison of the existing two-group interfacial area transport equation source and sink terms for large diameter channels with recently collected interfacial area concentration measurements (Schlegel et al., 2012, 2014. Int. J. Heat Fluid Flow 47, 42) has indicated that the model does not perform well in predicting interfacial area transport outside of the range of flow conditions used in the original benchmarking effort. In order to reduce the error in the prediction of interfacial area concentration by the interfacial area transport equation, several constitutive relations have been updated including the turbulence model and relative velocity correlation. The transport equation utilizing these updated models has been modified by updating the inter-group transfer and Group 2 coalescence and disintegration kernels using an expanded range of experimental conditions extending to pipe sizes of 0.304 m [12 in.], gas velocities of up to nearly 11 m/s [36.1 ft/s] and liquid velocities of up to 2 m/s [6.56 ft/s], as well as conditions with both bubbly flow and cap-bubbly flow injection (Schlegel et al., 2012, 2014). The modifications to the transport equation have resulted in a decrease in the RMS error for void fraction and interfacial area concentration from 17.32% to 12.3% and 21.26% to 19.6%. The combined RMS error, for both void fraction and interfacial area concentration, is below 15% for most of the experiments used in the comparison, a distinct improvement over the previous version of the model.

  16. Urban Mass Transportation.

    Science.gov (United States)

    Mervine, K. E.

    This bibliography is part of a series of Environmental Resource Packets prepared under a grant from EXXON Education Foundation. The most authoritative and accessible references in the urban transportation field are reviewed. The authors, publisher, point of view, level, and summary are given for each reference. The references are categorized…

  17. Molecular dynamics study of interfacial thermal transport between silicene and substrates.

    Science.gov (United States)

    Zhang, Jingchao; Hong, Yang; Tong, Zhen; Xiao, Zhihuai; Bao, Hua; Yue, Yanan

    2015-10-07

    In this work, the interfacial thermal transport across silicene and various substrates, i.e., crystalline silicon (c-Si), amorphous silicon (a-Si), crystalline silica (c-SiO2) and amorphous silica (a-SiO2) are explored by classical molecular dynamics (MD) simulations. A transient pulsed heating technique is applied in this work to characterize the interfacial thermal resistance in all hybrid systems. It is reported that the interfacial thermal resistances between silicene and all substrates decrease nearly 40% with temperature from 100 K to 400 K, which is due to the enhanced phonon couplings from the anharmonicity effect. Analysis of phonon power spectra of all systems is performed to interpret simulation results. Contradictory to the traditional thought that amorphous structures tend to have poor thermal transport capabilities due to the disordered atomic configurations, it is calculated that amorphous silicon and silica substrates facilitate the interfacial thermal transport compared with their crystalline structures. Besides, the coupling effect from substrates can improve the interface thermal transport up to 43.5% for coupling strengths χ from 1.0 to 2.0. Our results provide fundamental knowledge and rational guidelines for the design and development of the next-generation silicene-based nanoelectronics and thermal interface materials.

  18. Implementation of a new interfacial mass and energy transfer model in RETRAN-3D

    International Nuclear Information System (INIS)

    Macian, R.; Cebulh, P.; Coddington, P.; Paulsen, M.

    1999-01-01

    The RETRAN-3D MOD002.0 best estimate code includes a five-equation flow field model developed to deal with situations in which thermodynamic non-equilibrium phenomena are important. Several applications of this model to depressurization and pressurization transients showed serious convergence problems. An analysis of the causes for the numerical instabilities identified the models for interfacial heat and mass transfer as the source of the problems. A new interfacial mass and energy transfer model has thus been developed and implemented in RETRAN-3D. The heat transfer for each phase is equal to the product of the interfacial area density, a heat transfer coefficient and the temperature difference between the interface at saturation and the bulk temperature of the respective phase. However, in the context of RETRAN-3D, the vapor remains saturated in a two-phase volume, and no vapor heat transfer is thus calculated. The values of interfacial area density and heat transfer coefficient are obtained based on correlations appropriate for different flow regimes. A flow regime map, based on the work of Taitel and Dukler, with void fraction and mixture mass flux as map coordinates, is used to identify the flow regime present in a given volume. The new model has performed well when assessed against data from four experimental facilities covering depressurization, condensation and steady state void distribution. The results also demonstrate the viability of the approach followed to develop the new model for a five-equation based code. (author)

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

    International Nuclear Information System (INIS)

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

    2005-03-01

    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

  20. 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

    2005-03-01

    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.

  1. The effect of interfacial layers on charge transport in organic solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Mbuyise, Xolani G.; Tonui, Patrick; Mola, Genene Tessema, E-mail: mola@ukzn.ac.za

    2016-09-01

    The effect of interfacial buffer layers in organic photovoltaic cell (OPV) whose active layer is composed of poly(3 hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend was studied. The electrical properties of OPV devices produced with and without interfacial layers are compared and discussed in terms of measured parameters of the cells. The charge transport properties showed significant difference on the mobility and activation factor between the two types of device structures. The life time measurements in the unprotected conditions are also presented and discussed.

  2. Development of two-group interfacial area transport equation for confined flow-2. Model evaluation

    International Nuclear Information System (INIS)

    Sun, Xiaodong; Kim, Seungjin; Ishii, Mamoru; Beus, Stephen G.

    2003-01-01

    The bubble interaction mechanisms have been analytically modeled in the first paper of this series to provide mechanistic constitutive relations for the two-group interfacial area transport equation (IATE), which was proposed to dynamically solve the interfacial area concentration in the two-fluid model. This paper presents the evaluation approach and results of the two-group IATE based on available experimental data obtained in confined flow, namely, 11 data sets in or near bubbly flow and 13 sets in cap-turbulent and churn-turbulent flow. The two-group IATE is evaluated in steady state, one-dimensional form. Also, since the experiments were performed under adiabatic, air-water two-phase flow conditions, the phase change effect is omitted in the evaluation. To account for the inter-group bubble transport, the void fraction transport equation for Group-2 bubbles is also used to predict the void fraction for Group-2 bubbles. Agreement between the data and the model predictions is reasonably good and the average relative difference for the total interfacial area concentration between the 24 data sets and predictions is within 7%. The model evaluation demonstrates the capability of the two-group IATE focused on the current confined flow to predict the interfacial area concentration over a wide range of flow regimes. (author)

  3. One-group interfacial area transport in vertical air-water bubbly flow

    International Nuclear Information System (INIS)

    Wu, Q.; Kim, S.; Ishii, M.; Beus, S.G.

    1997-01-01

    In the two-fluid model for two-phase flows, interfacial area concentration is one of the most important closure relations that should be obtained from careful mechanistic modeling. The objective of this study is to develop a one-group interfacial area transport equation together with the modeling of the source and sink terms due to bubble breakage and coalescence. For bubble coalescence, two mechanisms are considered to be dominant in vertical two-phase bubbly flow. These are the random collisions between bubbles due to turbulence in the flow field, and the wake entrainment process due to the relative motion of the bubbles in the wake region of a seeding bubble. For bubble breakup, the impact of turbulent eddies is considered. These phenomena are modeled individually, resulting in a one-group interfacial area concentration transport equation with certain parameters to be determined from experimental data. Compared to the measured axial distribution of the interfacial area concentration under various flow conditions, these parameters are obtained for the reduced one-group, one-dimensional transport equation. The results indicate that the proposed models for bubble breakup and coalescence are appropriate

  4. Characteristics of Gas-liquid Mass Transfer and Interfacial Area in a Bubble Column

    International Nuclear Information System (INIS)

    Lim, Dae Ho; Yoo, Dong Jun; Kang, Yong

    2015-01-01

    Characteristics of gas-liquid mass transfer and interfacial area were investigated in a bubble column of diameter and height of 0.102 m and 2.5 m, respectively. Effects of gas and liquid velocities on the volumetric gas-liquid mass transfer coefficient (k L a), interfacial area (a) and liquid side true mass transfer coefficient (k L ) were examined. The interfacial area and volumetric gas-liquid mass transfer coefficient were determined directly by adopting the simultaneous physical desorption of O 2 and chemical absorption of CO 2 in the column. The values of k L a and a increased with increasing gas velocity but decreased with increasing liquid velocity in the bubble column which was operated in the churn turbulent flow regime. The value of k L increased with increasing gas velocity but did not change considerably with increasing liquid velocity. The liquid side mass transfer was found to be related closely to the liquid circulation as well as the effective contacting frequency between the bubbles and liquid phases

  5. Characteristics of Gas-liquid Mass Transfer and Interfacial Area in a Bubble Column

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Dae Ho; Yoo, Dong Jun; Kang, Yong [Chungnam National University, Daejeon (Korea, Republic of)

    2015-02-15

    Characteristics of gas-liquid mass transfer and interfacial area were investigated in a bubble column of diameter and height of 0.102 m and 2.5 m, respectively. Effects of gas and liquid velocities on the volumetric gas-liquid mass transfer coefficient (k{sub L}a), interfacial area (a) and liquid side true mass transfer coefficient (k{sub L}) were examined. The interfacial area and volumetric gas-liquid mass transfer coefficient were determined directly by adopting the simultaneous physical desorption of O{sub 2} and chemical absorption of CO{sub 2} in the column. The values of k{sub L}a and a increased with increasing gas velocity but decreased with increasing liquid velocity in the bubble column which was operated in the churn turbulent flow regime. The value of k{sub L} increased with increasing gas velocity but did not change considerably with increasing liquid velocity. The liquid side mass transfer was found to be related closely to the liquid circulation as well as the effective contacting frequency between the bubbles and liquid phases.

  6. Reduction of benzene and naphthalene mass transfer from crude oils by aging-induced interfacial films.

    Science.gov (United States)

    Ghoshal, Subhasis; Pasion, Catherine; Alshafie, Mohammed

    2004-04-01

    Semi-rigid films or skins form at the interface of crude oil and water as a result of the accumulation of asphaltene and resin fractions when the water-immiscible crude oil is contacted with water for a period of time or "aged". The time varying patterns of area-independent mass transfer coefficients of two compounds, benzene and naphthalene, for dissolution from crude oil and gasoline were determined. Aqueous concentrations of the compounds were measured in the eluent from flow-through reactors, where a nondispersed oil phase and constant oil-water interfacial area were maintained. For Brent Blend crude oil and for gasoline amended with asphaltenes and resins, a rapid decrease in both benzene and naphthalene mass transfer coefficients over the first few days of aging was observed. The mass transfer coefficients of the two target solutes were reduced by up to 80% over 35 d although the equilibrium partition coefficients were unchanged. Aging of gasoline, which has negligible amounts of asphaltene and resin, did not result in a change in the solute mass transfer coefficients. The study demonstrates that formation of crude oil-water interfacial films comprised of asphaltenes and resins contribute to time-dependent decreases in rates of release of environmentally relevant solutes from crude oils and may contribute to the persistence of such solutes at crude oil-contaminated sites. It is estimated that the interfacial film has an extremely low film mass transfer coefficient in the range of 10(-6) cm/min.

  7. Imaging mass spectrometry tackles interfacial challenges in electrochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Xiao-Ying

    2017-12-01

    Electrochemistry has played a significant role in many research fields. Owing to its sensitivity and selectivity, in situ electroanalysis has been widely used as a fast and economical means for achieving outstanding results. Although many spectroscopic techniques have been used in electrochemistry, the challenges to capture short-lived intermediate species as a result of electron transfer in the buried solid electrode and electrolyte solution interface remains a grand challenge. In situ imaging mass spectrometry (IMS) recently has been extended to capture transient species in electrochemistry. This review intends to summarize newest development of IMS and its applications in advancing fundamental electrochemistry.

  8. Modified two-fluid model for the two-group interfacial area transport equation

    International Nuclear Information System (INIS)

    Sun Xiaodong; Ishii, Mamoru; Kelly, Joseph M.

    2003-01-01

    This paper presents a modified two-fluid model that is ready to be applied in the approach of the two-group interfacial area transport equation. The two-group interfacial area transport equation was developed to provide a mechanistic constitutive relation for the interfacial area concentration in the two-fluid model. In the two-group transport equation, bubbles are categorized into two groups: spherical/distorted bubbles as Group 1 while cap/slug/churn-turbulent bubbles as Group 2. Therefore, this transport equation can be employed in the flow regimes spanning from bubbly, cap bubbly, slug to churn-turbulent flows. However, the introduction of the two groups of bubbles requires two gas velocity fields. Yet it is not practical to solve two momentum equations for the gas phase alone. In the current modified two-fluid model, a simplified approach is proposed. The momentum equation for the averaged velocity of both Group-1 and Group-2 bubbles is retained. By doing so, the velocity difference between Group-1 and Group-2 bubbles needs to be determined. This may be made either based on simplified momentum equations for both Group-1 and Group-2 bubbles or by a modified drift-flux model

  9. Framework for reactive mass transport

    DEFF Research Database (Denmark)

    Jensen, Mads Mønster; Johannesson, Björn; Geiker, Mette Rica

    2014-01-01

    Reactive transport modeling is applicable for a range of porous materials. Here the modeling framework is focused on cement-based materials, where ion diffusion and migration are described by the Poisson-Nernst-Planck equation system. A two phase vapor/liquid flow model, with a sorption hysteresis...... description is coupled to the system. The mass transport is solved by using the finite element method where the chemical equilibrium is solved explicitly by an operator splitting method. The IPHREEQC library is used as chemical equilibrium solver. The equation system, solved by IPHREEQC, is explained...

  10. Interfacial Phonon Transport Through Si/Ge Multilayer Film Using Monte Carlo Scheme With Spectral Transmissivity

    Directory of Open Access Journals (Sweden)

    Xin Ran

    2018-05-01

    Full Text Available The knowledge of interfacial phonon transport accounting for detailed phonon spectral properties is desired because of its importance for design of nanoscale energy systems. In this work, we investigate the interfacial phonon transport through Si/Ge multilayer films using an efficient Monte Carlo scheme with spectral transmissivity, which is validated for cross-plane phonon transport through both Si/Ge single-layer and Si/Ge bi-layer thin films by comparing with the discrete-ordinates solution. Different thermal boundary conductances between even the same material pair are declared at different interfaces within the multilayer system. Furthermore, the thermal boundary conductances at different interfaces show different trends with varying total system size, with the variation slope, very different as well. The results are much different from those in the bi-layer thin film or periodic superlattice. These unusual behaviors can be attributed to the combined interfacial local non-equilibrium effect and constraint effect from other interfaces.

  11. Prediction of interfacial area transport in a scaled 8×8 BWR rod bundle

    Energy Technology Data Exchange (ETDEWEB)

    Yang, X.; Schlegel, J.P.; Liu, Y.; Paranjape, S.; Hibiki, T.; Ishii, M. [School of Nuclear Engineering, Purdue University, 400 Central Dr., West Lafayette, IN 47907-2017 (United States); Bajorek, S.; Ireland, A. [U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001 (United States)

    2016-12-15

    In the two-fluid model, it is important to give an accurate prediction for the interfacial area concentration. In order to achieve this goal, the interfacial area transport equation has been developed. This study focuses on the benchmark of IATE performance in a rod bundle geometry. A set of interfacial area concentration source and sink term models are proposed for a rod bundle geometry based on the confined channel IATE model. This model was selected as a basis because of the relative similarity of the two geometries. Benchmarking of the new model with interfacial area concentration data in an 8×8 rod bundle test section which has been scaled from an actual BWR fuel bundle is performed. The model shows good agreement in bubbly and cap-bubbly flows, which are similar in many types of geometries, while it shows some discrepancy in churn-turbulent flow regime. This discrepancy may be due to the geometrical differences between the actual rod bundle test facility and the facility used to collect the data which benchmarked the original source and sink models.

  12. Modeling strategy of the source and sink terms in the two-group interfacial area transport equation

    International Nuclear Information System (INIS)

    Ishii, Mamoru; Sun Xiaodong; Kim, Seungjin

    2003-01-01

    This paper presents the general strategy for modeling the source and sink terms in the two-group interfacial area transport equation. The two-group transport equation is applicable in bubbly, cap bubbly, slug, and churn-turbulent flow regimes to predict the change of the interfacial area concentration. This dynamic approach has an advantage of flow regime-independence over the conventional empirical correlation approach for the interfacial area concentration in the applications with the two-fluid model. In the two-group interfacial area transport equation, bubbles are categorized into two groups: spherical/distorted bubbles as Group 1 and cap/slug/churn-turbulent bubbles as Group 2. Thus, two sets of equations are used to describe the generation and destruction rates of bubble number density, void fraction, and interfacial area concentration for the two groups of bubbles due to bubble expansion and compression, coalescence and disintegration, and phase change. Based upon a detailed literature review of the research on the bubble interactions, five major bubble interaction mechanisms are identified for the gas-liquid two-phase flow of interest. A systematic integral approach, in which the significant variations of bubble volume and shape are accounted for, is suggested for the modeling of two-group bubble interactions. To obtain analytical forms for the various bubble interactions, a simplification is made for the bubble number density distribution function

  13. Enhanced interfacial thermal transport in pnictogen tellurides metallized with a lead-free solder alloy

    Energy Technology Data Exchange (ETDEWEB)

    Devender,; Ramanath, Ganpati, E-mail: Ramanath@rpi.edu [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Lofgreen, Kelly; Devasenathipathy, Shankar; Swan, Johanna; Mahajan, Ravi [Intel Corporation, Assembly Test and Technology Development, Chandler, Arizona 85226 (United States); Borca-Tasciuc, Theodorian [Department of Mechanical Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2015-11-15

    Controlling thermal transport across metal–thermoelectric interfaces is essential for realizing high efficiency solid-state refrigeration and waste-heat harvesting power generation devices. Here, the authors report that pnictogen chalcogenides metallized with bilayers of Sn{sub 96.5}Ag{sub 3}Cu{sub 0.5} solder and Ni barrier exhibit tenfold higher interfacial thermal conductance Γ{sub c} than that obtained with In/Ni bilayer metallization. X-ray diffraction and x-ray spectroscopy indicate that reduced interdiffusion and diminution of interfacial SnTe formation due to Ni layer correlates with the higher Γ{sub c}. Finite element modeling of thermoelectric coolers metallized with Sn{sub 96.5}Ag{sub 3}Cu{sub 0.5}/Ni bilayers presages a temperature drop ΔT ∼ 22 K that is 40% higher than that obtained with In/Ni metallization. Our results underscore the importance of controlling chemical intermixing at solder–metal–thermoelectric interfaces to increase the effective figure of merit, and hence, the thermoelectric cooling efficiency. These findings should facilitate the design and development of lead-free metallization for pnictogen chalcogenide-based thermoelectrics.

  14. Computational analysis of interfacial attachment kinetics and transport phenomena during liquid phase epitaxy of mercury cadmium telluride

    Energy Technology Data Exchange (ETDEWEB)

    Rasin, Igal; Brandon, Simon [Dept. of Chemical Engineering, Technion, Haifa 32000 (Israel); Ben Dov, Anne; Grimberg, Ilana; Klin, Olga; Weiss, Eliezer [SCD-Semi-Conductor Devices, P.O. Box 2250/99, Haifa 31021 (Israel)

    2010-07-01

    Deposition of mercury cadmium telluride (MCT) thin films, on lattice matched cadmium zinc telluride substrates, is often achieved via Liquid Phase Epitaxy (LPE). The yield and quality of these films, required for the production of infrared detector devices, is to a large extent limited by lack of knowledge regarding details of physical phenomena underlying the deposition process. Improving the understanding of these phenomena and their impact on the quality of the resultant films is therefore an important goal which can be achieved through relevant computational and/or experimental studies. We present a combined computational and experimental effort aimed at elucidating physical phenomena underlying the LPE of MCT via a slider growth process. The focus of the presentation will be results generated by a time-dependent three-dimensional model of mass transport, fluid flow, and interfacial attachment kinetics, which we have developed and applied in the analysis of this LPE process. These results, combined with experimental analyses, lead to an improved understanding of the role of different transport and kinetic phenomena underlying this growth process.

  15. Minimizing performance degradation induced by interfacial recombination in perovskite solar cells through tailoring of the transport layer electronic properties

    Directory of Open Access Journals (Sweden)

    Liang Xu

    2018-03-01

    Full Text Available The performance of hybrid organic-inorganic metal halide perovskite solar cells is investigated using one-dimensional drift-diffusion device simulations. We study the effects of interfacial defect density, doping concentration, and electronic level positions of the charge transport layer (CTL. Choosing CTLs with a favorable band alignment, rather than passivating CTL-perovskite interfacial defects, is shown to be beneficial for maintaining high power-conversion efficiency, due to reduced minority carrier density arising from a favorable local electric field profile. Insights from this study provide theoretical guidance on practical selection of CTL materials for achieving high-performance perovskite solar cells.

  16. Interfacial area transport in two-phase flows in a scaled 8X8 rod bundle geometry at elevated pressures

    International Nuclear Information System (INIS)

    Yang, X; Schlegel, J.P.; Paranjape, S.; Liu, Y.; Chen, S.W.; Hibiki, T.; Ishii, M.

    2011-01-01

    To improve the prediction accuracy and robustness of the next-generation thermal-hydraulics system analysis code, analytical and experimental research has been undertaken to develop the Interfacial Area Transport Equation (IATE) in a scaled 8x8 rod bundle geometry at elevated pressure conditions. The experiments performed include local measurements of void fraction, interfacial area concentration, and gas velocity at several axial locations using the innovative four-sensor conductivity probe. The test conditions cover a wide range of flow regimes from bubbly, cap-bubbly, cap-turbulent to churn-turbulent at 100 kPa and 300 kPa pressure conditions and the obtained data indicates some spacer effects on the flow parameters. The bubble groups are classified into two groups (Group-1: spherical and distorted bubbles, Group-2: cap and churn turbulent bubbles) based on the bubble transport characteristics. The area-averaged interfacial area transport data have been compared to the prediction by the one-dimensional two-group IATE with mechanistically modeled IAC source and sink terms. The one-group IATE is able to predict the bubbly-flow interfacial area within ±15% error under two pressure conditions. The two-group IATE performance is also very promising in the cap-bubbly flow and churn-turbulent flow regimes, with average error of about ±20%. (author)

  17. Prediction of adiabatic bubbly flows in TRACE using the interfacial area transport equation

    International Nuclear Information System (INIS)

    Talley, J.; Worosz, T.; Kim, S.; Mahaffy, J.; Bajorek, S.; Tien, K.

    2011-01-01

    The conventional thermal-hydraulic reactor system analysis codes utilize a two-field, two-fluid formulation to model two-phase flows. To close this model, static flow regime transition criteria and algebraic relations are utilized to estimate the interfacial area concentration (a i ). To better reflect the continuous evolution of two-phase flow, an experimental version of TRACE is being developed which implements the interfacial area transport equation (IATE) to replace the flow regime based approach. Dynamic estimation of a i is provided through the use of mechanistic models for bubble coalescence and disintegration. To account for the differences in bubble interactions and drag forces, two-group bubble transport is sought. As such, Group 1 accounts for the transport of spherical and distorted bubbles, while Group 2 accounts for the cap, slug, and churn-turbulent bubbles. Based on this categorization, a two-group IATE applicable to the range of dispersed two-phase flows has been previously developed. Recently, a one-group, one-dimensional, adiabatic IATE has been implemented into the TRACE code with mechanistic models accounting for: (1) bubble breakup due to turbulent impact of an eddy on a bubble, (2) bubble coalescence due to random collision driven by turbulent eddies, and (3) bubble coalescence due to the acceleration of a bubble in the wake region of a preceding bubble. To demonstrate the enhancement of the code's capability using the IATE, experimental data for a i , void fraction, and bubble velocity measured by a multi-sensor conductivity probe are compared to both the IATE and flow regime based predictions. In total, 50 air-water vertical co-current upward and downward bubbly flow conditions in pipes with diameters ranging from 2.54 to 20.32 cm are evaluated. It is found that TRACE, using the conventional flow regime relation, always underestimates a i . Moreover, the axial trend of the a i prediction is always quasi-linear because a i in the

  18. Carrier Transport Enhancement in Conjugated Polymers through Interfacial Self-Assembly of Solution-State Aggregates

    KAUST Repository

    Zhao, Kui

    2016-07-13

    We demonstrate that local and long range orders of poly(3-hexylthiophene) (P3HT) semicrystalline films can be synergistically improved by combining chemical functionalization of the dielectric surface with solution-state disentanglement and pre-aggregation of P3HT in a theta solvent, leading to a very significant enhancement of the field effect carrier mobility. The pre-aggregation and surface functionalization effects combine to enhance the carrier mobility nearly 100-fold as compared with standard film preparation by spin-coating, and nearly 10-fold increase over the benefits of pre-aggregation alone. In situ quartz crystal microbalance with dissipation (QCM-D) experiments reveal enhanced deposition of pre-aggregates on surfaces modified with an alkyl-terminated self-assembled monolayer (SAM) in comparison to un-aggregated polymer chains. Additional investigations reveal the combined pre-aggregation and surface functionalization significantly enhances local order of the conjugated polymer through planarization and extension of the conjugated backbone of the polymer which clearly translate to significant improvements of carrier transport at the semiconductor-dielectric interface in organic thin film transistors. This study points to opportunities in combining complementary routes, such as well-known pre-aggregation with substrate chemical functionalization, to enhance the polymer self-assembly and improve its interfacial order with benefits for transport properties.

  19. Investigation of one-dimensional interfacial area transport for vertical upward air–water two-phase flow in an annular channel at elevated pressures

    International Nuclear Information System (INIS)

    Ozar, B.; Brooks, C.S.; Euh, D.J.; Hibiki, T.; Ishii, M.

    2013-01-01

    Highlights: • Interfacial area transport equation (IATE) for a rectangular duct is modified for an annulus. • IATE predicts interfacial area transport in bubbly-to-churn flow. • Scalability of IATE to elevated pressure conditions is validated. • Detailed 1D interfacial area transport data are presented. • Detailed interfacial area transport mechanisms are discussed. -- Abstract: The interfacial area transport of vertical, upward, air–water two-phase flows in an annular channel has been investigated at different system pressures. The inner and outer diameters of the annular channel were 19.1 mm and 38.1 mm, respectively. Twenty three inlet flow conditions were selected, which covered bubbly, cap-bubbly, and churn-turbulent flows. These flow conditions also overlapped with twelve conditions of a previous study for comparison. The local flow parameters, such as void fractions, interfacial area concentrations (IAC), and bubble interface velocities, were measured at nine radial positions for the three axial locations and converted into area-averaged parameters. The axial evolutions of local flow structure were interpreted in terms of bubble coalescence, breakup, expansion of the gas-phase due to pressure drop and system pressure. An assessment of interfacial area transport equation (IATE) was made and compared with the experimental data. A discussion of the comparison between model prediction and the experimental results were made

  20. Investigation of one-dimensional interfacial area transport for vertical upward air–water two-phase flow in an annular channel at elevated pressures

    Energy Technology Data Exchange (ETDEWEB)

    Ozar, B., E-mail: ozar@fauske.com [School of Nuclear Engineering, Purdue University, 400 Central Drive, West Lafayette, IN 47907-2017 (United States); Brooks, C.S. [School of Nuclear Engineering, Purdue University, 400 Central Drive, West Lafayette, IN 47907-2017 (United States); Euh, D.J. [Korea Atomic Energy Research Institute, 150 Deokjin, Yuseong, Daejeon 305-353 (Korea, Republic of); Hibiki, T.; Ishii, M. [School of Nuclear Engineering, Purdue University, 400 Central Drive, West Lafayette, IN 47907-2017 (United States)

    2013-10-15

    Highlights: • Interfacial area transport equation (IATE) for a rectangular duct is modified for an annulus. • IATE predicts interfacial area transport in bubbly-to-churn flow. • Scalability of IATE to elevated pressure conditions is validated. • Detailed 1D interfacial area transport data are presented. • Detailed interfacial area transport mechanisms are discussed. -- Abstract: The interfacial area transport of vertical, upward, air–water two-phase flows in an annular channel has been investigated at different system pressures. The inner and outer diameters of the annular channel were 19.1 mm and 38.1 mm, respectively. Twenty three inlet flow conditions were selected, which covered bubbly, cap-bubbly, and churn-turbulent flows. These flow conditions also overlapped with twelve conditions of a previous study for comparison. The local flow parameters, such as void fractions, interfacial area concentrations (IAC), and bubble interface velocities, were measured at nine radial positions for the three axial locations and converted into area-averaged parameters. The axial evolutions of local flow structure were interpreted in terms of bubble coalescence, breakup, expansion of the gas-phase due to pressure drop and system pressure. An assessment of interfacial area transport equation (IATE) was made and compared with the experimental data. A discussion of the comparison between model prediction and the experimental results were made.

  1. A modified two-fluid model for the application of two-group interfacial area transport equation

    International Nuclear Information System (INIS)

    Sun, X.; Ishii, M.; Kelly, J.

    2003-01-01

    This paper presents the modified two-fluid model that is ready to be applied in the approach of the two-group interfacial area transport equation. The two-group interfacial area transport equation was developed to provide a mechanistic constitutive relation for the interfacial area concentration in the two-fluid model. In the two-group transport equation, bubbles are categorized into two groups: spherical/distorted bubbles as Group 1 while cap/slug/churn-turbulent bubbles as Group 2. Therefore, this transport equation can be employed in the flow regimes spanning from bubbly, cap bubbly, slug to churn-turbulent flows. However, the introduction of the two groups of bubbles requires two gas velocity fields. Yet it is not desirable to solve two momentum equations for the gas phase alone. In the current modified two-fluid model, a simplified approach is proposed. The momentum equation for the averaged velocity of both Group-1 and Group-2 bubbles is retained. By doing so, the velocity difference between Group-1 and Group-2 bubbles needs to be determined. This may be made either based on simplified momentum equations for both Group-1 and Group-2 bubbles or by a modified drift-flux model

  2. Modeling of isothermal bubbly flow with interfacial area transport equation and bubble number density approach

    Energy Technology Data Exchange (ETDEWEB)

    Sari, Salih [Hacettepe University, Department of Nuclear Engineering, Beytepe, 06800 Ankara (Turkey); Erguen, Sule [Hacettepe University, Department of Nuclear Engineering, Beytepe, 06800 Ankara (Turkey); Barik, Muhammet; Kocar, Cemil; Soekmen, Cemal Niyazi [Hacettepe University, Department of Nuclear Engineering, Beytepe, 06800 Ankara (Turkey)

    2009-03-15

    In this study, isothermal turbulent bubbly flow is mechanistically modeled. For the modeling, Fluent version 6.3.26 is used as the computational fluid dynamics solver. First, the mechanistic models that simulate the interphase momentum transfer between the gas (bubbles) and liquid (continuous) phases are investigated, and proper models for the known flow conditions are selected. Second, an interfacial area transport equation (IATE) solution is added to Fluent's solution scheme in order to model the interphase momentum transfer mechanisms. In addition to solving IATE, bubble number density (BND) approach is also added to Fluent and this approach is also used in the simulations. Different source/sink models derived for the IATE and BND models are also investigated. The simulations of experiments based on the available data in literature are performed by using IATE and BND models in two and three-dimensions. The results show that the simulations performed by using IATE and BND models agree with each other and with the experimental data. The simulations performed in three-dimensions give better agreement with the experimental data.

  3. Modeling of isothermal bubbly flow with interfacial area transport equation and bubble number density approach

    International Nuclear Information System (INIS)

    Sari, Salih; Erguen, Sule; Barik, Muhammet; Kocar, Cemil; Soekmen, Cemal Niyazi

    2009-01-01

    In this study, isothermal turbulent bubbly flow is mechanistically modeled. For the modeling, Fluent version 6.3.26 is used as the computational fluid dynamics solver. First, the mechanistic models that simulate the interphase momentum transfer between the gas (bubbles) and liquid (continuous) phases are investigated, and proper models for the known flow conditions are selected. Second, an interfacial area transport equation (IATE) solution is added to Fluent's solution scheme in order to model the interphase momentum transfer mechanisms. In addition to solving IATE, bubble number density (BND) approach is also added to Fluent and this approach is also used in the simulations. Different source/sink models derived for the IATE and BND models are also investigated. The simulations of experiments based on the available data in literature are performed by using IATE and BND models in two and three-dimensions. The results show that the simulations performed by using IATE and BND models agree with each other and with the experimental data. The simulations performed in three-dimensions give better agreement with the experimental data

  4. 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

    2005-04-26

    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.

  5. Electroless Formation of Hybrid Lithium Anodes for Fast Interfacial Ion Transport

    KAUST Repository

    Choudhury, Snehashis; Tu, Zhengyuan; Stalin, Sanjuna; Vu, Duylinh; Fawole, Kristen; Gunceler, Deniz; Sundararaman, Ravishankar; Archer, Lynden A.

    2017-01-01

    Rechargeable batteries based on metallic anodes are of interest for fundamental and application-focused studies of chemical and physical kinetics of liquids at solid interfaces. Approaches that allow facile creation of uniform coatings on these metals to prevent physical contact with liquid electrolytes, while enabling fast ion transport, are essential to address chemical instability of the anodes. Here, we report a simple electroless ion-exchange chemistry for creating coatings of indium on lithium. By means of joint density functional theory and interfacial characterization experiments, we show that In coatings stabilize Li by multiple processes, including exceptionally fast surface diffusion of lithium ions and high chemical resistance to liquid electrolytes. Indium coatings also undergo reversible alloying reactions with lithium ions, facilitating design of high-capacity hybrid In-Li anodes that use both alloying and plating approaches for charge storage. By means of direct visualization, we further show that the coatings enable remarkably compact and uniform electrodeposition. The resultant In-Li anodes are shown to exhibit minimal capacity fade in extended galvanostatic cycling when paired with commercial-grade cathodes.

  6. Electroless Formation of Hybrid Lithium Anodes for Fast Interfacial Ion Transport

    KAUST Repository

    Choudhury, Snehashis

    2017-08-17

    Rechargeable batteries based on metallic anodes are of interest for fundamental and application-focused studies of chemical and physical kinetics of liquids at solid interfaces. Approaches that allow facile creation of uniform coatings on these metals to prevent physical contact with liquid electrolytes, while enabling fast ion transport, are essential to address chemical instability of the anodes. Here, we report a simple electroless ion-exchange chemistry for creating coatings of indium on lithium. By means of joint density functional theory and interfacial characterization experiments, we show that In coatings stabilize Li by multiple processes, including exceptionally fast surface diffusion of lithium ions and high chemical resistance to liquid electrolytes. Indium coatings also undergo reversible alloying reactions with lithium ions, facilitating design of high-capacity hybrid In-Li anodes that use both alloying and plating approaches for charge storage. By means of direct visualization, we further show that the coatings enable remarkably compact and uniform electrodeposition. The resultant In-Li anodes are shown to exhibit minimal capacity fade in extended galvanostatic cycling when paired with commercial-grade cathodes.

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

    International Nuclear Information System (INIS)

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

    2005-01-01

    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

  8. Electroless formation of hybrid lithium anodes for fast interfacial ion transport

    Energy Technology Data Exchange (ETDEWEB)

    Choudhury, Snehashis; Stalin, Sanjuna; Vu, Duylinh; Fawole, Kristen; Archer, Lynden A. [School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY (United States); Tu, Zhengyuan [Department of Material Science and Engineering, Cornell University, Ithaca, NY (United States); Gunceler, Deniz [Department of Physics, Cornell University, Ithaca, NY (United States); Sundararaman, Ravishankar [Material Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY (United States)

    2017-10-09

    Rechargeable batteries based on metallic anodes are of interest for fundamental and application-focused studies of chemical and physical kinetics of liquids at solid interfaces. Approaches that allow facile creation of uniform coatings on these metals to prevent physical contact with liquid electrolytes, while enabling fast ion transport, are essential to address chemical instability of the anodes. Here, we report a simple electroless ion-exchange chemistry for creating coatings of indium on lithium. By means of joint density functional theory and interfacial characterization experiments, we show that In coatings stabilize Li by multiple processes, including exceptionally fast surface diffusion of lithium ions and high chemical resistance to liquid electrolytes. Indium coatings also undergo reversible alloying reactions with lithium ions, facilitating design of high-capacity hybrid In-Li anodes that use both alloying and plating approaches for charge storage. By means of direct visualization, we further show that the coatings enable remarkably compact and uniform electrodeposition. The resultant In-Li anodes are shown to exhibit minimal capacity fade in extended galvanostatic cycling when paired with commercial-grade cathodes. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Electromigration-induced drift in damascene and plasma-etched Al(Cu). II. Mass transport mechanisms in bamboo interconnects

    Science.gov (United States)

    Proost, Joris; Maex, Karen; Delacy, Luc

    2000-01-01

    We have discussed electromigration (EM)-induced drift in polycrystalline damascene versus reactive ion etched (RIE) Al(Cu) in part I. For polycrystalline Al(Cu), mass transport is well documented to occur through sequential stages : an incubation period (attributed to Cu depletion beyond a critical length) followed by the Al drift stage. In this work, the drift behavior of bamboo RIE and damascene Al(Cu) is analyzed. Using Blech-type test structures, mass transport in RIE lines was shown to proceed both by lattice and interfacial diffusion. The dominating mechanism depends on the Cu distribution in the line, as was evidenced by comparing as-patterned (lattice EM) and RTP-annealed (interface EM) samples. The interfacial EM only occurs at metallic interfaces. In that case, Cu alloying was observed to retard Al interfacial mass transport, giving rise to an incubation time. Although the activation energy for the incubation time was found similar to the one controlling Al lattice drift, for which no incubation time was observed, lattice EM is preferred over interfacial EM because it is insensitive to enhancing geometrical effects upon scaling. When comparing interfacial electromigration in RIE with bamboo damascene Al(Cu), with the incubation time rate controlling for both, the higher EM threshold observed for damascene was shown to be insufficient to compensate for its significantly increased Cu depletion rate, contrary to the case of polycrystalline Al(Cu) interconnects. Two factors were demonstrated to contribute. First, there are more metallic interfaces, intrinsically related to the use of wetting or barrier layers in recessed features. Second, specific to this study, the additional formation of TiAl3 at the trench sidewalls further enhanced the Cu depletion rate, and reduced the rate-controlling incubation time. A separate drift study on RIE via-type test structures indicated that it is very difficult to suppress interfacial mass transport in favor of lattice EM

  10. Data acquisition of mass transport parameters

    International Nuclear Information System (INIS)

    Iwasaki, Riyo; Hama, Katsuhiro; Morikawa, Keita; Hosoya, Shinichi

    2017-02-01

    Tono Geoscience Center of Japan Atomic Energy Agency (JAEA) has been carrying out the Mizunami Underground Research Laboratory (MIU) Project, which is a scientific study understanding the deep geological environment as a basis of research and development for geological disposal of high level radioactive wastes. The aim of the MIU project is to establish comprehensive techniques for the investigation, analysis and assessment of the deep geological environment in fractured crystalline rock, and to develop a range of engineering techniques for deep underground application. This project has three overlapping phases: Surface-based investigation phase (Phase I), Construction phase (Phase II), and Operation phase (Phase III). Currently, the project is being carried out under the Phase III. Mass transport study is mainly performed as part of Phase III project. In Phase III, the goal of mass transport study is to obtain a better understanding of mass transport phenomena in the geological environment as well as to develop technologies for measurement of the mass transport parameters, model construction, numerical analysis and validation of those technologies. This study was planned to understand the influence of the geological characteristics of fracture on the mass transport parameters. This report presents the results of diffusion experiment, observation of polished thin section, sorption experiment and porophysicality measurement. (author)

  11. Texture mapping via optimal mass transport.

    Science.gov (United States)

    Dominitz, Ayelet; Tannenbaum, Allen

    2010-01-01

    In this paper, we present a novel method for texture mapping of closed surfaces. Our method is based on the technique of optimal mass transport (also known as the "earth-mover's metric"). This is a classical problem that concerns determining the optimal way, in the sense of minimal transportation cost, of moving a pile of soil from one site to another. In our context, the resulting mapping is area preserving and minimizes angle distortion in the optimal mass sense. Indeed, we first begin with an angle-preserving mapping (which may greatly distort area) and then correct it using the mass transport procedure derived via a certain gradient flow. In order to obtain fast convergence to the optimal mapping, we incorporate a multiresolution scheme into our flow. We also use ideas from discrete exterior calculus in our computations.

  12. Mass-transport limitation to in-cloud reaction rates: Implications of new accommodation coefficient measurements

    International Nuclear Information System (INIS)

    Schwartz, S.E.

    1988-10-01

    Although it has been recognized for some time that the rate of reactive uptake of gases in cloudwater can depend on the value of the mass-accommodation coefficient (α) describing interfacial mass transport (MT), definitive evaluation of such rates is only now becoming possible with the availability of measurements of α for gases of atmospheric interest at air-water interfaces. Examination of MT limitation to the rate of in-cloud aqueous-phase oxidation of SO 2 by O 3 and H 2 O 2 shows that despite the low value of α/sub O3/ (5 /times/ 10/sup /minus/4/), interfacial MT of this species is not limiting under essentially all conditions of interest; the high values of α for SO 2 (≥ 0.2) and H 2 O 2 (≥ 0.08) indicate no interfacial MT limitation for these species also. Although gas- and aqueous-phase MT can be limiting under certain extremes of conditions, treating the system as under chemical kinetic control is generally an excellent approximation. Interfacial MT limitation also is found not to hinder the rate of H 2 O 2 formation by aqueous-phase disproportionation of HO 2 . Finally, the rapid uptake of N 2 O 5 by cloud droplets implies that the yield of aqueous HNO 3 from in-cloud gas-phase oxidation of NO 2 by O 3 can be substantial even under daytime conditions. This report consists of copies of viewgraphs prepared for this presentation

  13. Development and validation of bubble breakup and coalescence constitutive models for the one-group interfacial area transport equation

    International Nuclear Information System (INIS)

    Pellacani, Filippo

    2012-01-01

    A local mechanistic model for bubble coalescence and breakup for the one-group interfacial area transport equation has been developed, in agreement and within the limits of the current understanding, based on an exhaustive survey of the theory and of the state of the art models for bubble dynamics simulation. The new model has been tested using the commercial 3D CFD code ANSYS CFX. Upward adiabatic turbulent air-water bubbly flow has been simulated and the results have been compared with the data obtained in the experimental facility PUMA. The range of the experimental data available spans between 0.5 to 2 m/s liquid velocity and 5 to 15 % volume fraction. For the implementation of the models, both the monodispersed and the interfacial area transport equation approaches have been used. The first one to perform a detailed analysis of the forces and models to reproduce the dynamic of the dispersed phase adequately and to be used in the next phases of the work. Also two different bubble induced turbulence models have been tested to consider the effect of the presence of the gas phase on the turbulence of the liquid phase. The interfacial area transport equation has been successfully implemented into the CFD code and the state of the art breakup and coalescence models have been used for simulation. The limitations of the actual theory have been shown and a new bubble interactions model has been developed. The simulations showed that a considerable improvement is achieved if compared to the state of the art closure models. Limits in the implementation derive from the actual understanding and formulation of the bubbly dynamics. A strong dependency on the interfacial non-drag force models and coefficients have been shown. More experimental and theory work needs to be done in this field to increase the prediction capability of the simulation tools regarding the distribution of the phases along the pipe radius.

  14. Radiochemical measurement of mass transport in sodium

    International Nuclear Information System (INIS)

    Cooper, M.H.; Chiang, S.H.

    1976-01-01

    Mass transport processes in the sodium coolant of Liquid Metal Fast Breeder Reactors (LMFBRs) are significant in determining rates of corrosion and deposition of radioactive nuclides from the fuel cladding, deposition and cold trapping of fission products from defect or failed fuel, carbon and nitrogen redistribution in the containment materials, and removal of impurities by cold trapping or hot trapping. Mass transport between rotating, concentric cylinders in molten sodium has been investigated using a unique radiochemical method. Long-lived (33 year) cesium-137, dissolved in the sodium, decays radioactively emitting a beta to barium-137m, which decays with a short half-life (2.6 minutes) emitting a gamma. Cesium is weakly adsorbed and remains in solution, while the barium is strongly adsorbed on the stainless steel surfaces. Hence, by measuring the barium-137m activity on movable stainless steel surfaces, one can calculate the mass transport to that surface. Mass transfer coefficients in sodium measured by this method are in agreement with published heat transfer correlations when the effect of the volumetric mass source is taken into account. Hence, heat transfer correlations can be confidently utilized by analogy in estimating mass transfer in liquid-metal systems

  15. Interfacial area transport of vertical upward air-water two-phase flow in an annulus at elevated pressures

    International Nuclear Information System (INIS)

    Ozar, Basar; Hibiki, Takashi; Ishii, Mamoru; Euh, Dong-Jin

    2009-01-01

    The interfacial area transport of vertical, upward, air-water two-phase flows in an annular channel has been investigated at different system pressures. The inner and outer diameters of the annular channel were 19.1 mm and 38.1 mm, respectively. Twenty three inlet flow conditions were selected, which coverED bubbly, cap-slug, and churn-turbulent flows. These flow conditions also overlapped with twelve conditions of our previous study for comparison. The local flow parameters, such as void fractions, interfacial area concentrations (IAC), and bubble interface velocities, were measured at nine radial positions for the three axial locations (z/D h =52, 149 and 230) and converted into area-averaged parameters. The axial evolutions of local flow structure was interpreted in terms of bubble coalescence, breakup, expansion of the gas-phase due to pressure drop and system pressure. An assessment of interfacial area transport equation (IATE) was made and compared with the experimental data. A discussion of the comparison between model prediction and the experimental results were made. (author)

  16. Mass transport in thin supported silica membranes

    NARCIS (Netherlands)

    Benes, Nieck Edwin

    2000-01-01

    In this thesis multi-component mass transport in thin supported amorphous silica membranes is discussed. These membranes are micro-porous, with pore diameters smaller than 4Å and show high fluxes for small molecules (such as hydrogen) combined with high selectivities for these molecules with respect

  17. A Note on Diffusive Mass Transport.

    Science.gov (United States)

    Haynes, Henry W., Jr.

    1986-01-01

    Current chemical engineering textbooks teach that the driving force for diffusive mass transport in ideal solutions is the gradient in mole fraction. This is only true for ideal solution liquids. Therefore, it is shown that the appropriate driving force for use with ideal gases is the gradient in partial pressure. (JN)

  18. Satellite measurements of aerosol mass and transport

    Energy Technology Data Exchange (ETDEWEB)

    Fraser, R.S.; Kaufman, Y.J.; Mahoney, R.L.

    1984-01-01

    The aerosol optical thickness over land is derived from satellite measurements of the radiance of scattered sunlight. These data are used to estimate the columnar mass density of particulate sulfur on a day with a large amount of sulfur. The horizontal transport of the particulate sulfur is calculated using wing vectors measured with rawins. 33 references, 7 figures, 1 table.

  19. Numerical simulations of air–water cap-bubbly flows using two-group interfacial area transport equation

    International Nuclear Information System (INIS)

    Wang, Xia; Sun, Xiaodong

    2014-01-01

    Highlights: • Two-group interfacial area transport equation was implemented into a three-field two-fluid model in Fluent. • Numerical model was developed for cap-bubbly flows in a narrow rectangular flow channel. • Numerical simulations were performed for cap-bubbly flows with uniform void inlets and with central peaked void inlets. • Code simulations showed a significant improve over the conventional two-fluid model. - Abstract: Knowledge of cap-bubbly flows is of great interest due to its role in understanding of the flow regime transition from bubbly to slug or churn-turbulent flows. One of the key characteristics of such flows is the existence of bubbles in different sizes and shapes associated with their distinctive dynamic natures. This important feature is, however, generally not well captured by many available two-phase flow modeling approaches. In this study, a modified two-fluid model, namely a three-field, two-fluid model, is proposed. In this model, bubbles are categorized into two groups, i.e., spherical/distorted bubbles as Group-1 while cap/churn-turbulent bubbles as Group-2. A two-group interfacial area transport equation (IATE) is implemented to describe dynamic changes of interfacial structure in each bubble group, resulting from intra- and inter-group interactions and phase changes due to evaporation and condensation. Attention is also paid to appropriate constitutive relations of the interfacial transfers due to mechanical and thermal non-equilibrium between the different fields. The proposed three-field, two-fluid model is used to predict the phase distributions of adiabatic air–water flows in a confined rectangular duct. Good agreement between the simulation results from the proposed model and relevant experimental data indicates that the proposed model is promising as an improved computational tool for two-phase cap-bubbly flow simulations in rectangular flow ducts

  20. Phonon Transport at Crystalline Si/Ge Interfaces: The Role of Interfacial Modes of Vibration

    Science.gov (United States)

    Gordiz, Kiarash; Henry, Asegun

    2016-01-01

    We studied the modal contributions to heat conduction at crystalline Si and crystalline Ge interfaces and found that more than 15% of the interface conductance arises from less than 0.1% of the modes in the structure. Using the recently developed interface conductance modal analysis (ICMA) method along with a new complimentary methodology, we mapped the correlations between modes, which revealed that a small group of interfacial modes, which exist between 12–13 THz, exhibit extremely strong correlation with other modes in the system. It is found that these interfacial modes (e.g., modes with large eigen vectors for interfacial atoms) are enabled by the degree of anharmonicity near the interface, which is higher than in the bulk, and therefore allows this small group of modes to couple to all others. The analysis sheds light on the nature of localized vibrations at interfaces and can be enlightening for other investigations of localization. PMID:26979787

  1. Mass transfer rate through liquid membranes: interfacial chemical reactions and diffusion as simultaneous permeability controlling factors

    International Nuclear Information System (INIS)

    Danesi, P.R.; Horwitz, E.P.; Vandegrift, G.F.; Chiarizia, R.

    1981-01-01

    Equations describing the permeability of a liquid membrane to metal cations have been derived taking into account aqueous diffusion, membrane diffusion, and interfacial chemical reactions as simultaneous permeability controlling factors. Diffusion and chemical reactions have been coupled by a simple model analogous to the one previously described by us to represent liquid-liquid extraction kinetics. The derived equations, which make use of experimentally determined interfacial reaction mechanisms, qualitatively fit unexplained literature data regarding Cu 2+ transfer through liquid membranes. Their use to predict and optimize membrane permeability in practical separation processes by setting the appropriate concentration of the membrane carrier [LIX 64 (General Mills), a commercial β-hydroxy-oxime] and the pH of the aqueous copper feed solution is briefly discussed. 4 figures

  2. Effects of interfacial Fe electronic structures on magnetic and electronic transport properties in oxide/NiFe/oxide heterostructures

    International Nuclear Information System (INIS)

    Liu, Qianqian; Chen, Xi; Zhang, Jing-Yan; Yang, Meiyin; Li, Xu-Jing; Jiang, Shao-Long; Liu, Yi-Wei; Cao, Yi; Wu, Zheng-Long; Feng, Chun; Ding, Lei; Yu, Guang-Hua

    2015-01-01

    Highlights: • The magnetic and transport properties of oxide/NiFe/oxide films were studied. • The oxide (SiO 2 , MgO and HfO 2 ) has different elemental electronegativity. • Redox reaction at different NiFe/oxide interface is dependent on the oxide layer. • Different interfacial electronic structures shown by XPS influence the properties. - Abstract: We report that the magnetic and electronic transport properties in oxide/NiFe(2 nm)/oxide film (oxide = SiO 2 , MgO or HfO 2 ) are strongly influenced by the electronic structure of NiFe/oxide interface. Magnetic measurements show that there exist magnetic dead layers in the SiO 2 sandwiched film and MgO sandwiched film, whereas there is no magnetic dead layer in the HfO 2 sandwiched film. Furthermore, in the ultrathin SiO 2 sandwiched film no magnetoresistance (MR) is detected, while in the ultrathin MgO sandwiched film and HfO 2 sandwiched film the MR ratios reach 0.35% and 0.88%, respectively. The investigation by X-ray photoelectron spectroscopy reveals that the distinct interfacial redox reactions, which are dependent on the oxide layers, lead to the variation of magnetic and transport properties in different oxide/NiFe/oxide heterostructures

  3. Development of two-group interfacial area transport equation for confined flow-1. Modeling of bubble interactions

    International Nuclear Information System (INIS)

    Sun, Xiaodong; Kim, Seungjin; Ishii, Mamoru; Beus, Stephen G.

    2003-01-01

    This paper presents the modeling of bubble interaction mechanisms in the two-group interfacial area transport equation (IATE) for confined gas-liquid two-phase flow. The transport equation is applicable to bubbly, cap-turbulent, and churn-turbulent flow regimes. In the two-group IATE, bubbles are categorized into two groups: spherical/distorted bubbles as Group 1 and cap/slug/churn-turbulent bubbles as Group 2. Thus, two sets of equations are used to describe the generation and destruction rates of bubble number density, void fraction, and interfacial area concentration for the two groups of bubbles due to bubble expansion and compression, coalescence and disintegration, and phase change. Five major bubble interaction mechanisms are identified for the gas-liquid two-phase flow of interest, and are analytically modeled as the source/sink terms for the transport equations based on certain assumptions for the confined flow. These models include both intra-group (within a certain group) and inter-group (between two groups) bubble interactions. The comparisons of the prediction by the one-dimensional two-group IATE with experimental data are presented in the second paper of this series. (author)

  4. Strong Coupling between Nanofluidic Transport and Interfacial Chemistry: How Defect Reactivity Controls Liquid-Solid Friction through Hydrogen Bonding.

    Science.gov (United States)

    Joly, Laurent; Tocci, Gabriele; Merabia, Samy; Michaelides, Angelos

    2016-04-07

    Defects are inevitably present in nanofluidic systems, yet the role they play in nanofluidic transport remains poorly understood. Here, we report ab initio molecular dynamics (AIMD) simulations of the friction of liquid water on defective graphene and boron nitride sheets. We show that water dissociates at certain defects and that these "reactive" defects lead to much larger friction than the "nonreactive" defects at which water molecules remain intact. Furthermore, we find that friction is extremely sensitive to the chemical structure of reactive defects and to the number of hydrogen bonds they can partake in with the liquid. Finally, we discuss how the insight obtained from AIMD can be used to quantify the influence of defects on friction in nanofluidic devices for water treatment and sustainable energy harvesting. Overall, we provide new insight into the role of interfacial chemistry on nanofluidic transport in real, defective systems.

  5. Mass transport in propagating patterns of convection

    International Nuclear Information System (INIS)

    Moses, E.; Steinberg, V.

    1988-01-01

    Recent studies of propagating waves in an oscillatory convection of binary mixtures arise questions about transport properties of this flow. Optical visualization of a field of refraction index due to a shadowgraph technique gives information on the temperature and concentration fields. However, experimental observation of rolls propagating along the cell as travelling waves (TW) does not necessarily imply that mass is transferred hydrodynamically by the convective motion along the cell. One of the possibilities discussed, e.g., is that TW observed is only a phase propagation. The traditional examples of such situations come from the domain of linear, superposition-oriented physics. Acoustic waves transfer momentum and energy, but do not cause the mass to make excursions for their equilibrium point that are larger than the oscillation amplitude. In the case of nonlinear physics we were aware that small amplitude surface waves cause only small oscillatory motion round the equilibrium point, while larger amplitudes can cause the mass to start moving in the direction of the TW. This paper discussed the different possibilities of mass transfer by TW. 27 refs., 20 figs

  6. Decreased Charge Transport Barrier and Recombination of Organic Solar Cells by Constructing Interfacial Nanojunction with Annealing-Free ZnO and Al Layers.

    Science.gov (United States)

    Liu, Chunyu; Zhang, Dezhong; Li, Zhiqi; Zhang, Xinyuan; Guo, Wenbin; Zhang, Liu; Ruan, Shengping; Long, Yongbing

    2017-07-05

    To overcome drawbacks of the electron transport layer, such as complex surface defects and unmatched energy levels, we successfully employed a smart semiconductor-metal interfacial nanojunciton in organic solar cells by evaporating an ultrathin Al interlayer onto annealing-free ZnO electron transport layer, resulting in a high fill factor of 73.68% and power conversion efficiency of 9.81%. The construction of ZnO-Al nanojunction could effectively fill the surface defects of ZnO and reduce its work function because of the electron transfer from Al to ZnO by Fermi level equilibrium. The filling of surface defects decreased the interfacial carrier recombination in midgap trap states. The reduced surface work function of ZnO-Al remodulated the interfacial characteristics between ZnO and [6,6]-phenyl C71-butyric acid methyl ester (PC 71 BM), decreasing or even eliminating the interfacial barrier against the electron transport, which is beneficial to improve the electron extraction capacity. The filled surface defects and reduced interfacial barrier were realistically observed by photoluminescence measurements of ZnO film and the performance of electron injection devices, respectively. This work provides a simple and effective method to simultaneously solve the problems of surface defects and unmatched energy level for the annealing-free ZnO or other metal oxide semiconductors, paving a way for the future popularization in photovoltaic devices.

  7. Mass transfer and transport in salt repositories

    International Nuclear Information System (INIS)

    Pigford, T.H.; Chambre, P.L.; Lee, W.W.L.

    1989-02-01

    Salt is a unique rock isolation of nuclear waste because it is ''dry'' and nearly impermeable. In this paper we summarize some mass-transfer and transport analyses of salt repositories. First we analyses brine migration. Heating by high-level waste can cause brine in grain boundaries to move due to pressure-gradients. We analyze brine migration treating salt as a thermoelastic solid and found that brine migration is transient and localized. We use previously developed techniques to estimate release rates from waste packages by diffusion. Interbeds exist in salt and may be conduits for radionuclide migration. We analyze steady-state migration due to brine flow in the interbed, as a function of the Peclet number. Then we analyze transient mass transfer, both into the interbed and directly to salt, due only to diffusion. Finally we compare mass transfer rates of a waste cylinder in granite facing a fracture and in salt facing an interbed. In all cases, numerical illustrations of the analytic solution are given. 10 refs., 4 figs., 3 tabs

  8. Measurement of local interfacial area concentration in boiling loop

    International Nuclear Information System (INIS)

    Kyoung, Ho Kang; Byong, Jo Yun; Goon, Cherl Park

    1995-01-01

    An accurate prediction of two-phase flow is essential to many energy systems, including nuclear reactors. To model the two-phase flow, detailed information on the internal flow structure is required. The void fraction and interfacial area concentration are important fundamental parameters characterizing the internal structure of two-phase flow. The interfacial area concentration is defined as the available interfacial area per unit volume of the two-phase mixture in calculations of the interfacial transport of mass, momentum, and energy. Although a number of studies have been made in this area, the interfacial area concentration in two-phase flow has not been sufficiently investigated either experimentally or analytically. Most existing models for interfacial area concentration are limited to area-averaged interfacial area concentration in a flow channel. And the studies on local interfacial area concentration are limited to the case of air-water two-phase flow. However, the internal flow structure of steam-water two-phase flow having various bubble sizes could be quite different from that of air-water two-phase flow, the reliability of which weak in practical applications. In this study, the local interfacial area concentration steam-water two-phase flow has been investigated experimentally in a circular boiling tube having a heating rod in the center, and for the low flow with liquid superficial velocity <1 m/s

  9. Charge Recombination, Transport Dynamics, and Interfacial Effects in Organic Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Heeger, Alan [Univ. of California, Santa Barbara, CA (United States); Bazan, Guillermo [Univ. of California, Santa Barbara, CA (United States); Nguyen, Thuc-Quyen [Univ. of California, Santa Barbara, CA (United States); Wudl, Fred [Univ. of California, Santa Barbara, CA (United States)

    2015-02-12

    The need for renewable sources of energy is well known. Conversion of sunlight to electricity using solar cells is one of the most important opportunities for creating renewable energy sources. The research carried out under DE-FG02-08ER46535 focused on the science and technology of “Plastic” solar cells comprised of organic (i.e. carbon based) semiconductors. The Bulk Heterojunction concept involves a phase separated blend of two organic semiconductors each with dimensions in the nano-meter length scale --- one a material that functions as a donor for electrons and the other a material that functions as an acceptor for electrons. The nano-scale inter-penetrating network concept for “Plastic” solar cells was created at UC Santa Barbara. A simple measure of the impact of this concept can be obtained from a Google search which gives 244,000 “hits” for the Bulk Heterojunction solar cell. Research funded through this program focused on four major areas: 1. Interfacial effects in organic photovoltaics, 2. Charge transfer and photogeneration of mobile charge carriers in organic photovoltaics, 3. Transport and recombination of the photogenerated charge carriers in organic photovoltaics, 4. Synthesis of novel organic semiconducting polymers and semiconducting small molecules, including conjugated polyelectrolytes. Following the discovery of ultrafast charge transfer at UC Santa Barbara in 1992, the nano-organic (Bulk Heterojunction) concept was formulated. The need for a morphology comprising two interpenetrating bicontinuous networks was clear: one network to carry the photogenerated electrons (negative charge) to the cathode and one network to carry the photo-generated holes (positive charge) to the anode. This remarkable self-assembled network morphology has now been established using Transmission electron Microscopy (TEM) either in the Phase Contrast mode or via TEM-Tomography. The steps involved in delivering power from a solar cell to an external circuit

  10. Mathematical Investigation of Fluid Flow, Mass Transfer, and Slag-steel Interfacial Behavior in Gas-stirred Ladles

    Science.gov (United States)

    Cao, Qing; Nastac, Laurentiu

    2018-06-01

    In this study, the Euler-Euler and Euler-Lagrange modeling approaches were applied to simulate the multiphase flow in the water model and gas-stirred ladle systems. Detailed comparisons of the computational and experimental results were performed to establish which approach is more accurate for predicting the gas-liquid multiphase flow phenomena. It was demonstrated that the Euler-Lagrange approach is more accurate than the Euler-Euler approach. The Euler-Lagrange approach was applied to study the effects of the free surface setup, injected bubble size, gas flow rate, and slag layer thickness on the slag-steel interaction and mass transfer behavior. Detailed discussions on the flat/non-flat free surface assumption were provided. Significant inaccuracies in the prediction of the surface fluid flow characteristics were found when the flat free surface was assumed. The variations in the main controlling parameters (bubble size, gas flow rate, and slag layer thickness) and their potential impact on the multiphase fluid flow and mass transfer characteristics (turbulent intensity, mass transfer rate, slag-steel interfacial area, flow patterns, etc.,) in gas-stirred ladles were quantitatively determined to ensure the proper increase in the ladle refining efficiency. It was revealed that by injecting finer bubbles as well as by properly increasing the gas flow rate and the slag layer thickness, the ladle refining efficiency can be enhanced significantly.

  11. Mass transport in non crystalline metallic alloys

    International Nuclear Information System (INIS)

    Limoge, Y.

    1986-08-01

    In order to improve our understanding of mass transport in non crystalline metallic alloys we have developed indirect studies of diffusion based on electron irradiation and hydrostatic pressure effects upon crystallization. In a first part we present the models of crystallization which are used, then we give the experimental results. The main point is the first experimental measurement of the activation volume for diffusion in a metallic glass: the value of which is roughly one atomic volume. We show also recent quantitative results concerning radiation enhanced diffusion in metallic glasses (FeNi) 8 (PB) 2 and Ni 6 Nb 4 . In a last part we discuss the atomic model needed to explain our results

  12. Directing energy transport in organic photovoltaic cells using interfacial exciton gates.

    Science.gov (United States)

    Menke, S Matthew; Mullenbach, Tyler K; Holmes, Russell J

    2015-04-28

    Exciton transport in organic semiconductors is a critical, mediating process in many optoelectronic devices. Often, the diffusive and subdiffusive nature of excitons in these systems can limit device performance, motivating the development of strategies to direct exciton transport. In this work, directed exciton transport is achieved with the incorporation of exciton permeable interfaces. These interfaces introduce a symmetry-breaking imbalance in exciton energy transfer, leading to directed motion. Despite their obvious utility for enhanced exciton harvesting in organic photovoltaic cells (OPVs), the emergent properties of these interfaces are as yet uncharacterized. Here, directed exciton transport is conclusively demonstrated in both dilute donor and energy-cascade OPVs where judicious optimization of the interface allows exciton transport to the donor-acceptor heterojunction to occur considerably faster than when relying on simple diffusion. Generalized systems incorporating multiple exciton permeable interfaces are also explored, demonstrating the ability to further harness this phenomenon and expeditiously direct exciton motion, overcoming the diffusive limit.

  13. Implementation of a one-group interfacial area transport equation in a CFD code for the simulation of upward adiabatic bubbly flow

    International Nuclear Information System (INIS)

    Pellacani, F.; Macian, R.; Chiva, S.; Pena, C.

    2011-01-01

    In this paper upward, isothermal and turbulent bubbly flow in tubes is numerically modeled by using ANSYS CFX 12.1 with the aim of creating a basis for the reliable simulation of the flow along a vertical channel in a nuclear reactor as long term goal. Two approaches based on the mono-dispersed model and on the one-group Interfacial Area Transport Equation (IATE) model are used in order to maintain the computational effort as low as possible. This work represents the necessary step to implement a two-group interfacial area transport equation that will be able to dynamically represent the changes in interfacial structure in the transition region from bubbly to slug flow. The drag coefficient is calculated using the Grace model and the interfacial non-drag forces are also included. The Antal model is used for the calculation of the wall lubrication force coefficient. The lift force coefficient is obtained from the Tomiyama model. The turbulent dispersion force is taken into account and is modeled using the FAD (Favre averaged drag) approach, while the turbulence transfer is simulated with the Sato's model. The liquid velocity is in the range between 0.5 and 2 m/s and the average void fraction varies between 5 and 15%.The source and sink terms for break-up and coalescence needed for the calculation of the implemented Interfacial Area Density are those proposed by Yao and Morel. The model has been checked using experimental results by Mendez. Radial profile distributions of void fraction, interfacial area density and bubble mean diameter are shown at the axial position equivalent to z/D=56. The results obtained by the simulations have a good agreement with the experimental data but show also the need of a better study of the coalescence and breakup phenomena to develop more accurate interaction models. (author)

  14. On the Bias in the Danckwerts’ Plot Method for the Determination of the Gas–Liquid Mass-Transfer Coefficient and Interfacial Area

    Directory of Open Access Journals (Sweden)

    German E. Cortes Garcia

    2018-02-01

    Full Text Available The Danckwerts’ plot method is a commonly used graphical technique to independently determine the interfacial area and mass-transfer coefficient in gas–liquid contactors. The method was derived in 1963 when computational capabilities were limited and intensified process equipment did not exist. A numerical analysis of the underlying assumptions of the method in this paper has shown a bias in the technique, especially for situations where mass-transfer rates are intensified, or where there is limited liquid holdup in the bulk compared to the film layers. In fact, systematic errors of up to 50% in the interfacial area, and as high as 90% in the mass-transfer coefficients, can be expected for modern, intensified gas–liquid contactors, even within the commonly accepted validity limits of a pseudo-first-order reaction and Hatta numbers in the range of 0.3 < Ha < 3. Given the current computational capabilities and the intensified mass-transfer rates in modern gas–liquid contactors, it is therefore imperative that the equations for reaction and diffusion in the liquid films are numerically solved and subsequently used to fit the interfacial area and mass-transfer coefficient to experimental data, which would traditionally be used in the graphical Danckwerts’ method.

  15. The mass transportation problem in Illinois : a final report

    Science.gov (United States)

    1959-06-01

    Prepared by the State Mass Transportation Commission for the Honorable William G. Stratton, Governor of Illinois and the Honorable Members of the 71st General Assembly. The study contains the findings and recommendations of the Illinois State Mass Tr...

  16. Carrier Transport Enhancement in Conjugated Polymers through Interfacial Self-Assembly of Solution-State Aggregates

    KAUST Repository

    Zhao, Kui; Khan, Hadayat Ullah; Li, Ruipeng; Hu, Hanlin; Amassian, Aram

    2016-01-01

    and extension of the conjugated backbone of the polymer which clearly translate to significant improvements of carrier transport at the semiconductor-dielectric interface in organic thin film transistors. This study points to opportunities in combining

  17. Interfacial tension-induced transport of nonaqueous phase liquids in model aquifer systems

    International Nuclear Information System (INIS)

    Anderson, M.A.

    1994-01-01

    Nonaqueous phase liquids (NAPLs) such as organic solvents and fuel are common contaminants in soils and groundwater. Spills, leaking underground storage tanks, and improper disposal practices all result in the release and movement of NAPLs through soils. Movement of NAPLs through soil is considered to result from gravity- and /or capillarity-driven immiscible phase flow. Dispersive and convective transport of dissolved components, volatilization, sorption, and degradation are also considered important processes in NAPL contamination. An additional transport mechanism in which NAPLs spread on water surfaces due to differential adhesive and cohesive attractive forces is demonstrated in this study. 22 refs., 5 figs., 1 tab

  18. A Coupled Chemical and Mass Transport Model for Concrete Durability

    DEFF Research Database (Denmark)

    Jensen, Mads Mønster; Johannesson, Björn; Geiker, Mette Rica

    2012-01-01

    In this paper a general continuum theory is used to evaluate the service life of cement based materials, in terms of mass transport processes and chemical degradation of the solid matrix. The model established is a reactive mass transport model, based on an extended version of the Poisson-Nernst-...

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

    International Nuclear Information System (INIS)

    Rogers, J.D.

    1994-01-01

    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

  20. Interfacial Passivation of the p-Doped Hole-Transporting Layer Using General Insulating Polymers for High-Performance Inverted Perovskite Solar Cells.

    Science.gov (United States)

    Zhang, Fan; Song, Jun; Hu, Rui; Xiang, Yuren; He, Junjie; Hao, Yuying; Lian, Jiarong; Zhang, Bin; Zeng, Pengju; Qu, Junle

    2018-05-01

    Organic-inorganic lead halide perovskite solar cells (PVSCs), as a competing technology with traditional inorganic solar cells, have now realized a high power conversion efficiency (PCE) of 22.1%. In PVSCs, interfacial carrier recombination is one of the dominant energy-loss mechanisms, which also results in the simultaneous loss of potential efficiency. In this work, for planar inverted PVSCs, the carrier recombination is dominated by the dopant concentration in the p-doped hole transport layers (HTLs), since the F4-TCNQ dopant induces more charge traps and electronic transmission channels, thus leading to a decrease in open-circuit voltages (V OC ). This issue is efficiently overcome by inserting a thin insulating polymer layer (poly(methyl methacrylate) or polystyrene) as a passivation layer with an appropriate thickness, which allows for increases in the V OC without significantly sacrificing the fill factor. It is believed that the passivation layer attributes to the passivation of interfacial recombination and the suppression of current leakage at the perovskite/HTL interface. By manipulating this interfacial passivation technique, a high PCE of 20.3% is achieved without hysteresis. Consequently, this versatile interfacial passivation methodology is highly useful for further improving the performance of planar inverted PVSCs. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Magnetic anisotropy, damping, and interfacial spin transport in Pt/LSMO bilayers

    Directory of Open Access Journals (Sweden)

    H. K. Lee

    2016-05-01

    Full Text Available We report ferromagnetic resonance measurements of magnetic anisotropy and damping in epitaxial La0.7Sr0.3MnO3 (LSMO and Pt capped LSMO thin films on SrTiO3 (001 substrates. The measurements reveal large negative perpendicular magnetic anisotropy and a weaker uniaxial in-plane anisotropy that are unaffected by the Pt cap. The Gilbert damping of the bare LSMO films is found to be low α = 1.9(1 × 10−3, and two-magnon scattering is determined to be significant and strongly anisotropic. The Pt cap increases the damping by 50% due to spin pumping, which is also directly detected via inverse spin Hall effect in Pt. Our work demonstrates efficient spin transport across the Pt/LSMO interface.

  2. Magnetic anisotropy, damping, and interfacial spin transport in Pt/LSMO bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Lee, H. K., E-mail: hankl@uci.edu; Barsukov, I.; Yang, L.; Krivorotov, I. N. [Physics and Astronomy, University of California, Irvine, California 92697 (United States); Swartz, A. G.; Kim, B. [Geballe Laboratory for Advanced Materials, Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Hwang, H. Y. [Geballe Laboratory for Advanced Materials, Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States)

    2016-05-15

    We report ferromagnetic resonance measurements of magnetic anisotropy and damping in epitaxial La{sub 0.7}Sr{sub 0.3}MnO{sub 3} (LSMO) and Pt capped LSMO thin films on SrTiO{sub 3} (001) substrates. The measurements reveal large negative perpendicular magnetic anisotropy and a weaker uniaxial in-plane anisotropy that are unaffected by the Pt cap. The Gilbert damping of the bare LSMO films is found to be low α = 1.9(1) × 10{sup −3}, and two-magnon scattering is determined to be significant and strongly anisotropic. The Pt cap increases the damping by 50% due to spin pumping, which is also directly detected via inverse spin Hall effect in Pt. Our work demonstrates efficient spin transport across the Pt/LSMO interface.

  3. Terminology for mass transport and exchange

    DEFF Research Database (Denmark)

    Bassingthwaighte, J B; Chinard, F P; Crone, C

    1986-01-01

    Virtually all fields of physiological research now encompass various aspects of solute transport by convection, diffusion, and permeation across membranes. Accordingly, this set of terms, symbols, definitions, and units is proposed as a means of clear communication among workers in the physiologi......Virtually all fields of physiological research now encompass various aspects of solute transport by convection, diffusion, and permeation across membranes. Accordingly, this set of terms, symbols, definitions, and units is proposed as a means of clear communication among workers...... in the physiological, engineering, and physical sciences. The goal is to provide a setting for quantitative descriptions of physiological transport phenomena....

  4. Shape signature based on Ricci flow and optimal mass transportation

    Science.gov (United States)

    Luo, Wei; Su, Zengyu; Zhang, Min; Zeng, Wei; Dai, Junfei; Gu, Xianfeng

    2014-11-01

    A shape signature based on surface Ricci flow and optimal mass transportation is introduced for the purpose of surface comparison. First, the surface is conformally mapped onto plane by Ricci flow, which induces a measure on the planar domain. Second, the unique optimal mass transport map is computed that transports the new measure to the canonical measure on the plane. The map is obtained by a convex optimization process. This optimal transport map encodes all the information of the Riemannian metric on the surface. The shape signature consists of the optimal transport map, together with the mean curvature, which can fully recover the original surface. The discrete theories of surface Ricci flow and optimal mass transportation are explained thoroughly. The algorithms are given in detail. The signature is tested on human facial surfaces with different expressions accquired by structured light 3-D scanner based on phase-shifting method. The experimental results demonstrate the efficiency and efficacy of the method.

  5. Electric current induced forward and anomalous backward mass transport

    International Nuclear Information System (INIS)

    Somaiah, Nalla; Sharma, Deepak; Kumar, Praveen

    2016-01-01

    Multilayered test samples were fabricated in form of standard Blech structure, where W was used as the interlayer between SiO 2 substrate and Cu film. Electromigration test was performed at 250 °C by passing an electric current with a nominal density of 3.9  ×  10 10 A m −2 . In addition to the regular electromigration induced mass transport ensuing from the cathode towards the anode, we also observed anomalous mass transport from the anode to the cathode, depleting Cu from the anode as well. We propose an electromigration-thermomigration coupling based reasoning to explain the observed mass transport. (letter)

  6. Interfacial Redox Reactions Associated Ionic Transport in Oxide-Based Memories.

    Science.gov (United States)

    Younis, Adnan; Chu, Dewei; Shah, Abdul Hadi; Du, Haiwei; Li, Sean

    2017-01-18

    As an alternative to transistor-based flash memories, redox reactions mediated resistive switches are considered as the most promising next-generation nonvolatile memories that combine the advantages of a simple metal/solid electrolyte (insulator)/metal structure, high scalability, low power consumption, and fast processing. For cation-based memories, the unavailability of in-built mobile cations in many solid electrolytes/insulators (e.g., Ta 2 O 5 , SiO 2 , etc.) instigates the essential role of absorbed water in films to keep electroneutrality for redox reactions at counter electrodes. Herein, we demonstrate electrochemical characteristics (oxidation/reduction reactions) of active electrodes (Ag and Cu) at the electrode/electrolyte interface and their subsequent ions transportation in Fe 3 O 4 film by means of cyclic voltammetry measurements. By posing positive potentials on Ag/Cu active electrodes, Ag preferentially oxidized to Ag + , while Cu prefers to oxidize into Cu 2+ first, followed by Cu/Cu + oxidation. By sweeping the reverse potential, the oxidized ions can be subsequently reduced at the counter electrode. The results presented here provide a detailed understanding of the resistive switching phenomenon in Fe 3 O 4 -based memory cells. The results were further discussed on the basis of electrochemically assisted cations diffusions in the presence of absorbed surface water molecules in the film.

  7. Interfacial engineering of electron transport layer using Caesium Iodide for efficient and stable organic solar cells

    Science.gov (United States)

    Upama, Mushfika Baishakhi; Elumalai, Naveen Kumar; Mahmud, Md Arafat; Wright, Matthew; Wang, Dian; Xu, Cheng; Haque, Faiazul; Chan, Kah Howe; Uddin, Ashraf

    2017-09-01

    Polymer solar cells (PSCs) have gained immense research interest in the recent years predominantly due to low-cost, solution process-ability, and facile device fabrication. However, achieving high stability without compromising the power conversion efficiency (PCE) serves to be an important trade-off for commercialization. In line with this, we demonstrate the significance of incorporating a CsI/ZnO bilayer as electron transport layer (ETL) in the bulk heterojunction PSCs employing low band gap polymer (PTB7) and fullerene (PC71BM) as the photo-active layer. The devices with CsI/ZnO interlayer exhibited substantial enhancement of 800% and 12% in PCE when compared to the devices with pristine CsI and pristine ZnO as ETL, respectively. Furthermore, the UV and UV-ozone induced degradation studies revealed that the devices incorporating CsI/ZnO bilayer possess excellent decomposition stability (∼23% higher) over the devices with pristine ZnO counterparts. The incorporation of CsI between ITO and ZnO was found to favorably modify the energy-level alignment at the interface, contributing to the charge collection efficiency as well as protecting the adjacent light absorbing polymer layers from degradation. The mechanism behind the improvement in PCE and stability is analyzed using the electrochemical impedance spectroscopy and dark I-V characteristics.

  8. Metal/dielectric thermal interfacial transport considering cross-interface electron-phonon coupling: Theory, two-temperature molecular dynamics, and thermal circuit

    Science.gov (United States)

    Lu, Zexi; Wang, Yan; Ruan, Xiulin

    2016-02-01

    The standard two-temperature equations for electron-phonon coupled thermal transport across metal/nonmetal interfaces are modified to include the possible coupling between metal electrons with substrate phonons. The previous two-temperature molecular dynamics (TT-MD) approach is then extended to solve these equations numerically at the atomic scale, and the method is demonstrated using Cu/Si interface as an example. A key parameter in TT-MD is the nonlocal coupling distance of metal electrons and nonmetal phonons, and here we use two different approximations. The first is based on Overhauser's "joint-modes" concept, while we use an interfacial reconstruction region as the length scale of joint region rather than the phonon mean-free path as in Overhauser's original model. In this region, the metal electrons can couple to the joint phonon modes. The second approximation is the "phonon wavelength" concept where electrons couple to phonons nonlocally within the range of one phonon wavelength. Compared with the original TT-MD, including the cross-interface electron-phonon coupling can slightly reduce the total thermal boundary resistance. Whether the electron-phonon coupling within the metal block is nonlocal or not does not make an obvious difference in the heat transfer process. Based on the temperature profiles from TT-MD, we construct a new mixed series-parallel thermal circuit. We show that such a thermal circuit is essential for understanding metal/nonmetal interfacial transport, while calculating a single resistance without solving temperature profiles as done in most previous studies is generally incomplete. As a comparison, the simple series circuit that neglects the cross-interface electron-phonon coupling could overestimate the interfacial resistance, while the simple parallel circuit in the original Overhauser's model underestimates the total interfacial resistance.

  9. Transport and transformation of surface water masses across the ...

    African Journals Online (AJOL)

    Transport and transformation of surface water masses across the Mascarene Plateau during the Northeast Monsoon season. ... Mixing occurs in the central gap between intermediate water masses (Red Sea Water [RSW] and Antarctic Intermediate Water [AAIW]) as well as in the upper waters (Subtropical Surface Water ...

  10. Residual Stress Relaxation Induced by Mass Transport Through Interface of the Pd/SrTiO3

    Directory of Open Access Journals (Sweden)

    Nazarpour S

    2010-01-01

    Full Text Available Abstract Metal interconnections having a small cross-section and short length can be subjected to very large mass transport due to the passing of high current densities. As a result, nonlinear diffusion and electromigration effects which may result in device failure and electrical instabilities may be manifested. Various thicknesses of Pd were deposited over SrTiO3 substrate. Residual stress of the deposited film was evaluated by measuring the variation of d-spacing versus sin2ψ through conventional X-ray diffraction method. It has been found that the lattice misfit within film and substrate might be relaxed because of mass transport. Besides, the relation between residual intrinsic stress and oxygen diffusion through deposited film has been expressed. Consequently, appearance of oxide intermediate layer may adjust interfacial characteristics and suppress electrical conductivity by increasing electron scattering through metallic films.

  11. Space Geodesy Monitoring Mass Transport in Global Geophysical Fluids

    Science.gov (United States)

    Chao, Benjamin F.

    2004-01-01

    Mass transports occurring in the atmosphere-hydrosphere-cryosphere-solid Earth-core system (the 'global geophysical fluids') are important geophysical phenomena. They occur on all temporal and spatial scales. Examples include air mass and ocean circulations, oceanic and solid tides, hydrological water and idsnow redistribution, mantle processes such as post-glacial rebound, earthquakes and tectonic motions, and core geodynamo activities. The temporal history and spatial pattern of such mass transport are often not amenable to direct observations. Space geodesy techniques, however, have proven to be an effective tool in monitorihg certain direct consequences of the mass transport, including Earth's rotation variations, gravitational field variations, and the geocenter motion. Considerable advances have been made in recent years in observing and understanding of these geodynamic effects. This paper will use several prominent examples to illustrate the triumphs in research over the past years under a 'Moore's law' in space geodesy. New space missions and projects promise to further advance our knowledge about the global mass transports. The latter contributes to our understanding of the geophysical processes that produce and regulate the mass transports, as well as of the solid Earth's response to such changes in terms of Earth's mechanical properties.

  12. Lithium mass transport in ceramic breeder materials

    International Nuclear Information System (INIS)

    Blackburn, P.E.; Johnson, C.E.

    1990-01-01

    The objective of this activity is to measure the lithium vaporization from lithium oxide breeder material under differing temperature and moisture partial pressure conditions. Lithium ceramics are being investigated for use as tritium breeding materials. The lithium is readily converted to tritium after reacting with a neutron. With the addition of 1000 ppM H 2 to the He purge gas, the bred tritium is readily recovered from the blanket as HT and HTO above 400 degree C. Within the solid, tritium may also be found as LiOT which may transport lithium to cooler parts of the blanket. The pressure of LiOT(g), HTO(g), or T 2 O(g) above Li 2 O(s) is the same as that for reactions involving hydrogen. In our experiments we were limited to the use of hydrogen. The purpose of this work is to investigate the transport of LiOH(g) from the blanket material. 8 refs., 1 fig., 3 tabs

  13. Optimal urban networks via mass transportation

    CERN Document Server

    Buttazzo, Giuseppe; Stepanov, Eugene; Solimini, Sergio

    2009-01-01

    Recently much attention has been devoted to the optimization of transportation networks in a given geographic area. One assumes the distributions of population and of services/workplaces (i.e. the network's sources and sinks) are known, as well as the costs of movement with/without the network, and the cost of constructing/maintaining it. Both the long-term optimization and the short-term, "who goes where" optimization are considered. These models can also be adapted for the optimization of other types of networks, such as telecommunications, pipeline or drainage networks. In the monograph we study the most general problem settings, namely, when neither the shape nor even the topology of the network to be constructed is known a priori.

  14. Frontiers in Cancer Nanomedicine: Directing Mass Transport through Biological Barriers

    Science.gov (United States)

    Ferrari, Mauro

    2010-01-01

    The physics of mass transport within body compartments and across biological barriers differentiates cancers from healthy tissues. Variants of nanoparticles can be manufactured in combinatorially large sets, varying only one transport-affecting design parameter at a time. Nanoparticles can also be used as building blocks for systems that perform sequences of coordinated actions, in accordance to a prescribed logic. These are referred to as Logic-Embedded Vectors “(LEV)” in the following. Nanoparticles and LEVs are ideal probes for the determination of mass transport laws in tumors, acting as imaging contrast enhancers, and can be employed for the lesion-selective delivery of therapy. Their size, shape, density and surface chemistry dominate convective transport in the blood stream, margination, cell adhesion, selective cellular uptake, as well as sub-cellular trafficking and localization. As argued here, the understanding of transport differentials in cancer, termed ‘transport oncophysics’ unveils a new promising frontier in oncology: the development of lesion-specific delivery particulates that exploit mass transport differentials to deploy treatment of greater efficacy and reduced side effects. PMID:20079548

  15. Ion sampling and transport in Inductively Coupled Plasma Mass Spectrometry

    Science.gov (United States)

    Farnsworth, Paul B.; Spencer, Ross L.

    2017-08-01

    Quantitative accuracy and high sensitivity in inductively coupled plasma mass spectrometry (ICP-MS) depend on consistent and efficient extraction and transport of analyte ions from an inductively coupled plasma to a mass analyzer, where they are sorted and detected. In this review we examine the fundamental physical processes that control ion sampling and transport in ICP-MS and compare the results of theory and computerized models with experimental efforts to characterize the flow of ions through plasma mass spectrometers' vacuum interfaces. We trace the flow of ions from their generation in the plasma, into the sampling cone, through the supersonic expansion in the first vacuum stage, through the skimmer, and into the ion optics that deliver the ions to the mass analyzer. At each stage we consider idealized behavior and departures from ideal behavior that affect the performance of ICP-MS as an analytical tool.

  16. Mass Transport Through Carbon Nanotube-Polystyrene Bundles

    Science.gov (United States)

    Lin, Rongzhou; Tran, Tuan

    2016-05-01

    Carbon nanotubes have been widely used as test channels to study nanofluidic transport, which has been found to have distinctive properties compared to transport of fluids in macroscopic channels. A long-standing challenge in the study of mass transport through carbon nanotubes (CNTs) is the determination of flow enhancement. Various experimental investigations have been conducted to measure the flow rate through CNTs, mainly based on either vertically aligned CNT membranes or individual CNTs. Here, we proposed an alternative approach that can be used to quantify the mass transport through CNTs. This is a simple method relying on the use of carbon nanotube-polystyrene bundles, which are made of CNTs pulled out from a vertically aligned CNT array and glued together by polystyrene. We experimentally showed by using fluorescent tagging that the composite bundles allowed measureable and selective mass transport through CNTs. This type of composite bundle may be useful in various CNT research areas as they are simple to fabricate, less likely to form macroscopic cracks, and offer a high density of CNT pores while maintaining the aligned morphology of CNTs.

  17. Optimal partial mass transportation and obstacle Monge-Kantorovich equation

    Science.gov (United States)

    Igbida, Noureddine; Nguyen, Van Thanh

    2018-05-01

    Optimal partial mass transport, which is a variant of the optimal transport problem, consists in transporting effectively a prescribed amount of mass from a source to a target. The problem was first studied by Caffarelli and McCann (2010) [6] and Figalli (2010) [12] with a particular attention to the quadratic cost. Our aim here is to study the optimal partial mass transport problem with Finsler distance costs including the Monge cost given by the Euclidian distance. Our approach is different and our results do not follow from previous works. Among our results, we introduce a PDE of Monge-Kantorovich type with a double obstacle to characterize active submeasures, Kantorovich potential and optimal flow for the optimal partial transport problem. This new PDE enables us to study the uniqueness and monotonicity results for the active submeasures. Another interesting issue of our approach is its convenience for numerical analysis and computations that we develop in a separate paper [14] (Igbida and Nguyen, 2018).

  18. Coolant Chemistry Control: Oxygen Mass Transport in Lead Bismuth Eutectic

    International Nuclear Information System (INIS)

    Weisenburger, A.; Mueller, G.; Bruzzese, C.; Glass, A.

    2015-01-01

    In lead-bismuth cooled transmutation systems, oxygen, dissolved in the coolant at defined quantities, is required for stable long-term operation by assuring the formation of protective oxide scales on structural steel surfaces. Extracted oxygen must be permanently delivered to the system and distributed in the entire core. Therefore, coolant chemistry control involves detailed knowledge on oxygen mass transport. Beside the different flow regimes a core might have stagnant areas at which oxygen delivery can only be realised by diffusion. The difference between oxygen transport in flow paths and in stagnant zones is one of the targets of such experiments. To investigate oxygen mass transport in flowing and stagnant conditions, a dedicated facility was designed based on computational fluid dynamics (CFD). CFD also was applied to define the position of oxygen sensors and ultrasonic Doppler velocimetry transducers for flow measurements. This contribution will present the test facility, design relevant CFD calculations and results of first tests performed. (authors)

  19. Development and validation of a new solver based on the interfacial area transport equation for the numerical simulation of sub-cooled boiling with OpenFOAM CFD code for nuclear safety applications

    Energy Technology Data Exchange (ETDEWEB)

    Alali, Abdullah

    2014-02-21

    The one-group interfacial area transport equation has been coupled to a wall heat flux partitioning model in the framework of two-phase Eulerian approach using the OpenFOAM CFD code for better prediction of subcooled boiling phenomena which is essential for safety analysis of nuclear reactors. The interfacial area transport equation has been modified to include the effect of bubble nucleation at the wall and condensation by subcooled liquid in the bulk that governs the non-uniform bubble size distribution.

  20. Development and validation of a new solver based on the interfacial area transport equation for the numerical simulation of sub-cooled boiling with OpenFOAM CFD code for nuclear safety applications

    International Nuclear Information System (INIS)

    Alali, Abdullah

    2014-01-01

    The one-group interfacial area transport equation has been coupled to a wall heat flux partitioning model in the framework of two-phase Eulerian approach using the OpenFOAM CFD code for better prediction of subcooled boiling phenomena which is essential for safety analysis of nuclear reactors. The interfacial area transport equation has been modified to include the effect of bubble nucleation at the wall and condensation by subcooled liquid in the bulk that governs the non-uniform bubble size distribution.

  1. Thermodynamically coupled mass transport processes in a saturated clay

    International Nuclear Information System (INIS)

    Carnahan, C.L.

    1984-01-01

    Gradients of temperature, pressure, and fluid composition in saturated clays give rise to coupled transport processes (thermal and chemical osmosis, thermal diffusion, ultrafiltration) in addition to the direct processes (advection and diffusion). One-dimension transport of water and a solute in a saturated clay subjected to mild gradients of temperature and pressure was simulated numerically. When full coupling was accounted for, volume flux (specific discharge) was controlled by thermal osmosis and chemical osmosis. The two coupled fluxes were oppositely directed, producing a point of stagnation within the clay column. Solute flows were dominated by diffusion, chemical osmosis, and thermal osmosis. Chemical osmosis produced a significant flux of solute directed against the gradient of solute concentration; this effect reduced solute concentrations relative to the case without coupling. Predictions of mass transport in clays at nuclear waste repositories could be significantly in error if coupled transport processes are not accounted for. 14 refs., 8 figs

  2. Thermodynamically coupled mass transport processes in a saturated clay

    International Nuclear Information System (INIS)

    Carnahan, C.L.

    1984-11-01

    Gradients of temperature, pressure, and fluid composition in saturated clays give rise to coupled transport processes (thermal and chemical osmosis, thermal diffusion, ultrafiltration) in addition to the direct processes (advection and diffusion). One-dimensional transport of water and a solute in a saturated clay subjected to mild gradients of temperature and pressure was simulated numerically. When full coupling was accounted for, volume flux (specific discharge) was controlled by thermal osmosis and chemical osmosis. The two coupled fluxes were oppositely directed, producing a point of stagnation within the clay column. Solute flows were dominated by diffusion, chemical osmosis, and thermal osmosis. Chemical osmosis produced a significant flux of solute directed against the gradient of solute concentration; this effect reduced solute concentrations relative to the case without coupling. Predictions of mass transport in clays at nuclear waste repositories could be significantly in error if coupled transport processes are not accounted for. 14 references, 8 figures, 1 table

  3. Flow regime, void fraction and interfacial area transport and characteristics of co-current downward two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Lokanathan, Manojkumar [School of Mechanical Engineering, Purdue University, 585 Purdue Mall, West Lafayette, IN 47907-2088 (United States); Hibiki, Takashi [School of Nuclear Engineering, Purdue University, 400 Central Drive, West Lafayette, IN 47907-2017 (United States)

    2016-10-15

    Highlights: • Downward flow regime maps and models were studied for 25.4 to 101.6 mm pipe diameters. • Effect of flow inlet on flow transition, void & interfacial area profile were studied. • Bubble void profiles were associated with the interfacial forces for downward flow. • Flow regime pressure drop and interfacial friction factor were studied. • The most applicable and accurate downward drift-flux correlation was determined. - Abstract: Downward two-phase flow is observed in light water reactor accident scenarios such as loss of coolant accident (LOCA) and loss of heat sink accident (LOHS) due to loss of feed water or a secondary pipe break. Hence, a comprehensive literature review has been performed for the co-current downward two-phase flow with information on the flow regime transitions and flow characteristics for each regime in the downward flow. The review compares the experimental data of the flow regime map and the current available transition models. Objectivity of the data varies on the method utilized as a certain degree of subjectivity is still present in the most objective method. Nevertheless, experimental data through subjective methods such as direct visualization or analysis of a wire mesh sensor (WMS) data were still studied in this review. Despite the wide range of flow regime data for numerous pipe sizes, a consensus was not reached for the effect of pipe sizes on flow regime transition. However, it is known that a larger pipe results in greater degree of coalescence at lower gas flow rates (Hibiki et al., 2004). The introduction of a flow straightener at the inlet led to less coring and fluid rotation and inevitably, reduced bubble coalescence. This also resulted in the disappearance of the kinematic shock wave phenomenon, contrary to an inlet without a flow straightener. The effect of flow inlet, flow location, pipe diameter and bubble interfacial forces on the radial distribution as well as bubble coalescence and breakup rate

  4. Optimal Filtering in Mass Transport Modeling From Satellite Gravimetry Data

    Science.gov (United States)

    Ditmar, P.; Hashemi Farahani, H.; Klees, R.

    2011-12-01

    Monitoring natural mass transport in the Earth's system, which has marked a new era in Earth observation, is largely based on the data collected by the GRACE satellite mission. Unfortunately, this mission is not free from certain limitations, two of which are especially critical. Firstly, its sensitivity is strongly anisotropic: it senses the north-south component of the mass re-distribution gradient much better than the east-west component. Secondly, it suffers from a trade-off between temporal and spatial resolution: a high (e.g., daily) temporal resolution is only possible if the spatial resolution is sacrificed. To make things even worse, the GRACE satellites enter occasionally a phase when their orbit is characterized by a short repeat period, which makes it impossible to reach a high spatial resolution at all. A way to mitigate limitations of GRACE measurements is to design optimal data processing procedures, so that all available information is fully exploited when modeling mass transport. This implies, in particular, that an unconstrained model directly derived from satellite gravimetry data needs to be optimally filtered. In principle, this can be realized with a Wiener filter, which is built on the basis of covariance matrices of noise and signal. In practice, however, a compilation of both matrices (and, therefore, of the filter itself) is not a trivial task. To build the covariance matrix of noise in a mass transport model, it is necessary to start from a realistic model of noise in the level-1B data. Furthermore, a routine satellite gravimetry data processing includes, in particular, the subtraction of nuisance signals (for instance, associated with atmosphere and ocean), for which appropriate background models are used. Such models are not error-free, which has to be taken into account when the noise covariance matrix is constructed. In addition, both signal and noise covariance matrices depend on the type of mass transport processes under

  5. Selected Topics on Mass Transport in Gas-solid Interactions

    DEFF Research Database (Denmark)

    Somers, Marcel A.J.

    2004-01-01

    The present article is a short review containing examples of the role of mass transport in the solid state during gas-solid interactions. Examples are taken from the authors' research on the interaction of carbon and/or nitrogen with iron-based metals. Topics dealt with are diffusion-controlled d......The present article is a short review containing examples of the role of mass transport in the solid state during gas-solid interactions. Examples are taken from the authors' research on the interaction of carbon and/or nitrogen with iron-based metals. Topics dealt with are diffusion...... on the kinetics of phenomena in the solid state. Various experimental techniques were applied to investigate these phenomena; it is however beyond the scope of the present article to treat experimental conditions in detail. The interested reader is referred to the original work for in depth discussions...

  6. Mass transport in bedded salt and salt interbeds

    International Nuclear Information System (INIS)

    Hwang, Y.; Pigford, T.H.; Chambre, P.L.; Lee, W.W.L.

    1989-08-01

    Salt is the proposed host rock for geologic repositories of nuclear waste in several nations because it is nearly dry and probably impermeable. Although experiments and experience at potential salt sites indicate that salt may contain brine, the low porosity, creep, and permeability of salt make it still a good choice for geologic isolation. In this paper we summarize several mass-transfer and transport analyses of salt repositories. The mathematical details are given in our technical reports

  7. Mass transport thermodynamics in nonisothermal molecular liquid mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Semenov, Semen N [Institute for Biochemical Physics, Russian Academy of Sciences, Moscow (Russian Federation); Schimpf, M E [Department of Chemistry and Biochemistry, Boise State University, Boise, ID (United States)

    2009-10-31

    Mass transport in a nonisothermal binary molecular mixture is systematically discussed in terms of nonequilibrium thermodynamics, which for the first time allows a consistent and unambiguous description of the process. The thermodynamic and hydrodynamic approaches are compared, revealing that nonequilibrium thermodynamics and physicochemical hydrodynamics yield essentially the same results for molecular systems. The applicability limits for the proposed version of the thermodynamic approach are determined for large particles. (methodological notes)

  8. Membranes for nanometer-scale mass fast transport

    Science.gov (United States)

    Bakajin, Olgica [San Leandro, CA; Holt, Jason [Berkeley, CA; Noy, Aleksandr [Belmont, CA; Park, Hyung Gyu [Oakland, CA

    2011-10-18

    Nanoporous membranes comprising single walled, double walled, and multiwalled carbon nanotubes embedded in a matrix material were fabricated for fluid mechanics and mass transfer studies on the nanometer scale and commercial applications. Average pore size can be 2 nm to 20 nm, or seven nm or less, or two nanometers or less. The membrane can be free of large voids spanning the membrane such that transport of material such as gas or liquid occurs exclusively through the tubes. Fast fluid, vapor, and liquid transport are observed. Versatile micromachining methods can be used for membrane fabrication. A single chip can comprise multiple membranes. These membranes are a robust platform for the study of confined molecular transport, with applications in liquid and gas separations and chemical sensing including desalination, dialysis, and fabric formation.

  9. Photo-induced Mass Transport through Polymer Networks

    Science.gov (United States)

    Meng, Yuan; Anthamatten, Mitchell

    2014-03-01

    Among adaptable materials, photo-responsive polymers are especially attractive as they allow for spatiotemporal stimuli and response. We have recently developed a macromolecular network capable of photo-induced mass transport of covalently bound species. The system comprises of crosslinked chains that form an elastic network and photosensitive fluorescent arms that become mobile upon irradiation. We form loosely crosslinked polymer networks by Michael-Addition between multifunctional thiols and small molecule containing acrylate end-groups. The arms are connected to the network by allyl sulfide, that undergoes addition-fragmentation chain transfer (AFCT) in the presence of free radicals, releasing diffusible fluorophore. The networks are loaded with photoinitiator to allow for spatial modulation of the AFCT reactions. FRAP experiments within bulk elastomers are conducted to establish correlations between the fluorophore's diffusion coefficient and experimental variables such as network architecture, temperature and UV intensity. Photo-induced mass transport between two contacted films is demonstrated, and release of fluorophore into a solvent is investigated. Spatial and temporal control of mass transport could benefit drug release, printing, and sensing applications.

  10. Ring waves as a mass transport mechanism in air-driven core-annular flows.

    Science.gov (United States)

    Camassa, Roberto; Forest, M Gregory; Lee, Long; Ogrosky, H Reed; Olander, Jeffrey

    2012-12-01

    Air-driven core-annular fluid flows occur in many situations, from lung airways to engineering applications. Here we study, experimentally and theoretically, flows where a viscous liquid film lining the inside of a tube is forced upwards against gravity by turbulent airflow up the center of the tube. We present results on the thickness and mean speed of the film and properties of the interfacial waves that develop from an instability of the air-liquid interface. We derive a long-wave asymptotic model and compare properties of its solutions with those of the experiments. Traveling wave solutions of this long-wave model exhibit evidence of different mass transport regimes: Past a certain threshold, sufficiently large-amplitude waves begin to trap cores of fluid which propagate upward at wave speeds. This theoretical result is then confirmed by a second set of experiments that show evidence of ring waves of annular fluid propagating over the underlying creeping flow. By tuning the parameters of the experiments, the strength of this phenomenon can be adjusted in a way that is predicted qualitatively by the model.

  11. Kinematics of Mass Transport Deposits revealed by magnetic fabrics

    Science.gov (United States)

    Weinberger, R.; Levi, T.; Alsop, G. I.; Marco, S.

    2017-08-01

    The internal deformation and movement directions of Mass Transport Deposits (MTDs) are key factors in understanding the kinematics and dynamics of their emplacement. Although these are relatively easy to recover from well-bedded sediments, they are more difficult to deduce from massive beds without visible strain markers. In order to test the applicability of using anisotropy of magnetic susceptibility (AMS) to determine MTD movement, we compare AMS fabrics, with structural measurements of visible kinematic indicators. Our case study involves the structural analysis of slumped lake sediments extensively exposed in MTDs within the Dead Sea Basin. Structural analyses of MTDs outcropping for >100 km reveal radial transport directions toward the basin depocenter. We show that the AMS fabrics display the same transport directions as inferred from structural analyses. Based on this similarity, we outline a robust procedure to obtain the transport direction of slumped MTDs from AMS fabrics. Variations in the magnetic fabrics and anisotropies in fold-thrust systems within the slumps match the various structural domains. We therefore suggest that magnetic fabrics and anisotropy variations in drill cores may reflect internal deformation within the slumps rather than different slumps. Obtaining magnetic fabrics from MTDs provides a viable way to infer the transport directions and internal deformation of MTDs and reconstruct the basin depocenter in ancient settings. The present results also have implications beyond the kinematics of MTDs, as their geometry resembles fold-thrust systems in other geological settings, scales, and tectonic environments.

  12. Analysis of the contribution of sedimentation to bacterial mass transport in a parallel plate flow chamber

    NARCIS (Netherlands)

    Li, Jiuyi; Busscher, Henk J.; Norde, Willem; Sjollema, Jelmer

    2011-01-01

    In order to investigate bacterium-substratum interactions, understanding of bacterial mass transport is necessary. Comparisons of experimentally observed initial deposition rates with mass transport rates in parallel-plate-flow-chambers (PPFC) predicted by convective-diffusion yielded deposition

  13. Transport Visualization for Studying Mass Transfer and Solute Transport in Permeable Media

    International Nuclear Information System (INIS)

    Roy Haggerty

    2004-01-01

    Understanding and predicting mass transfer coupled with solute transport in permeable media is central to several energy-related programs at the US Department of Energy (e.g., CO 2 sequestration, nuclear waste disposal, hydrocarbon extraction, and groundwater remediation). Mass transfer is the set of processes that control movement of a chemical between mobile (advection-dominated) domains and immobile (diffusion- or sorption-dominated) domains within a permeable medium. Consequences of mass transfer on solute transport are numerous and may include (1) increased sequestration time within geologic formations; (2) reduction in average solute transport velocity by as much as several orders of magnitude; (3) long ''tails'' in concentration histories during removal of a solute from a permeable medium; (4) poor predictions of solute behavior over long time scales; and (5) changes in reaction rates due to mass transfer influences on pore-scale mixing of solutes. Our work produced four principle contributions: (1) the first comprehensive visualization of solute transport and mass transfer in heterogeneous porous media; (2) the beginnings of a theoretical framework that encompasses both macrodispersion and mass transfer within a single set of equations; (3) experimental and analytical tools necessary for understanding mixing and aqueous reaction in heterogeneous, granular porous media; (4) a clear experimental demonstration that reactive transport is often not accurately described by a simple coupling of the convection-dispersion equation with chemical reaction equations. The work shows that solute transport in heterogeneous media can be divided into 3 regimes--macrodispersion, advective mass transfer, and diffusive mass transfer--and that these regimes can be predicted quantitatively in binary media. We successfully predicted mass transfer in each of these regimes and verified the prediction by completing quantitative visualization experiments in each of the regimes, the

  14. Microphysics of mass-transport in coupled droplet-pairs at low Reynolds number and the role of convective dynamics

    Science.gov (United States)

    Dong, Qingming; Sau, Amalendu

    2016-06-01

    Interfacial mass-transport and redistribution in the micro-scale liquid droplets are important in diverse fields of research interest. The role of the "inflow" and the "outflow" type convective eddy-pairs in the entrainment of outer solute and internal relocation are examined for different homogeneous and heterogeneous water droplet pairs appearing in a tandem arrangement. Two micro-droplets of pure (rain) water interact with an oncoming outer air stream (Re ≤ 100) contaminated by uniformly distributed SO2. By virtue of separation/attachment induced non-uniform interfacial shear-stress gradient, the well-defined inflow/outflow type pairs of recirculating eddy-based convective motion quickly develops, and the eddies effectively attract/repel the accumulated outer solute and control the physical process of mass-transport in the droplet-pair. The non-uniformly shear-driven flow interaction and bifurcation of the circulatory internal flow lead to growth of important micro-scale "secondary" eddies which suitably regroup with the adjacent "primary" one to create the sustained inflow/outflow type convective dynamics. The presently derived flow characteristics and in-depth analysis help to significantly improve our understanding of the micro-droplet based transport phenomena in a wider context. By tuning "Re" (defined in terms of the droplet diameter and the average oncoming velocity of the outer air) and gap-ratio "α," the internal convective forcing and the solute entrainment efficiency could be considerably enhanced. The quantitative estimates for mass entrainment, convective strength, and saturation characteristics for different coupled micro-droplet pairs are extensively examined here for 0.2 ≤ α ≤ 2.0 and 30 ≤ Re ≤ 100. Interestingly, for the compound droplets, with suitably tuned radius-ratio "B" (of upstream droplet with respect to downstream one) the generated "inflow" type coherent convective dynamics helped to significantly augment the centre

  15. Mass transport and chloride ion complexes in occluded cell

    International Nuclear Information System (INIS)

    Tsuru, T.; Hashimoto, K.; Nishikata, A.; Haruyama, S.

    1989-01-01

    Changes in the transport and the concentration of ions in a model occluded cell are traced during galvanostatic anodic polarization of a mild steel and a stainless steel. Apparent transport numbers of anions and cations, which were estimated from chemical analysis of solution, were different from those calculated from known mobility data. At the initial stage of the polarization, the transport number of chloride ion was almost unity, and then decreased gradually. For the mild steel, the concentration of total chloride ion accumulated in the occluded compartment increased with the anodic charge passed, and the amount of chloride ion complexed with cations also increased. The chloride complex was estimated as FeCl + . For SUS304 stainless steel, the total chloride ion increased, however, the free chloride ion, which responded to an Ag/AgCl electrode remained approximately 2 mol/dm 3 . Therefore, most of the chloride ions transferred into the occluded cell formed complex ions, such as CrCl n 3-n . The number of chloride ion coordinated to ferrous and chromic ions was estimated from the data fo mass transport for the case of the mild steel and the stainless steel. (author) 9 refs., 14 figs

  16. Cellular automaton model of coupled mass transport and chemical reactions

    International Nuclear Information System (INIS)

    Karapiperis, T.

    1994-01-01

    Mass transport, coupled with chemical reactions, is modelled as a cellular automaton in which solute molecules perform a random walk on a lattice and react according to a local probabilistic rule. Assuming molecular chaos and a smooth density function, we obtain the standard reaction-transport equations in the continuum limit. The model is applied to the reactions a + b ↔c and a + b →c, where we observe interesting macroscopic effects resulting from microscopic fluctuations and spatial correlations between molecules. We also simulate autocatalytic reaction schemes displaying spontaneous formation of spatial concentration patterns. Finally, we propose and discuss the limitations of a simple model for mineral-solute interaction. (author) 5 figs., 20 refs

  17. Mass and charge transport in micro and nanofluidic channels

    DEFF Research Database (Denmark)

    Mortensen, Niels Asger; Olesen, Laurits Højgaard; Okkels, Fridolin

    2007-01-01

    and charge transport coefficients that satisfy Onsager relations. In the limit of nonoverlapping Debye layers the transport coefficients are simply expressed in terms of parameters of the electrolyte as well as the hydraulic radiusR ¼ 2A=P with Aand P being the cross-sectional area and perimeter......, respectively. In particular, we consider the limits of thin nonoverlapping as well as strongly overlapping Debye layers, respectively, and calculate the corrections to the hydraulic resistance due to electrohydrodynamic interactions.......We consider laminar flow of incompressible electrolytes in long, straight channels driven by pressure and electroosmosis. We use aHilbert space eigenfunction expansion to address the general problem of an arbitrary cross section and obtain general results in linear-response theory for the mass...

  18. Mass Transport: Circulatory System with Emphasis on Nonendothermic Species.

    Science.gov (United States)

    Crossley, Dane A; Burggren, Warren W; Reiber, Carl L; Altimiras, Jordi; Rodnick, Kenneth J

    2016-12-06

    Mass transport can be generally defined as movement of material matter. The circulatory system then is a biological example given its role in the movement in transporting gases, nutrients, wastes, and chemical signals. Comparative physiology has a long history of providing new insights and advancing our understanding of circulatory mass transport across a wide array of circulatory systems. Here we focus on circulatory function of nonmodel species. Invertebrates possess diverse convection systems; that at the most complex generate pressures and perform at a level comparable to vertebrates. Many invertebrates actively modulate cardiovascular function using neuronal, neurohormonal, and skeletal muscle activity. In vertebrates, our understanding of cardiac morphology, cardiomyocyte function, and contractile protein regulation by Ca2+ highlights a high degree of conservation, but differences between species exist and are coupled to variable environments and body temperatures. Key regulators of vertebrate cardiac function and systemic blood pressure include the autonomic nervous system, hormones, and ventricular filling. Further chemical factors regulating cardiovascular function include adenosine, natriuretic peptides, arginine vasotocin, endothelin 1, bradykinin, histamine, nitric oxide, and hydrogen sulfide, to name but a few. Diverse vascular morphologies and the regulation of blood flow in the coronary and cerebral circulations are also apparent in nonmammalian species. Dynamic adjustments of cardiovascular function are associated with exercise on land, flying at high altitude, prolonged dives by marine mammals, and unique morphology, such as the giraffe. Future studies should address limits of gas exchange and convective transport, the evolution of high arterial pressure across diverse taxa, and the importance of the cardiovascular system adaptations to extreme environments. © 2017 American Physiological Society. Compr Physiol 7:17-66, 2017. Copyright © 2017 John

  19. Vertical Transport of Sediment from Muddy Buoyant River Plumes in the Presence of Different Modes of Interfacial Instabilities

    Science.gov (United States)

    Strom, K.; Rouhnia, M.

    2016-12-01

    Previous studies have suggested that sedimentation from buoyant, muddy plumes lofting over clear saltwater can take place at rates higher than that expected from individual particle settling (i.e., CWs). Two potential drivers of enhanced sedimentation are flocculation and interfacial instabilities. We experimentally measured the sediment fluxes from each of these processes using two sets of laboratory experiments that investigate two different modes of instability, one driven by sediment settling and one driven by fluid shear. The settling-driven and shear-driven instability experiments were carried out in a stagnant stratification tank and a stratification flume respectively. In both sets, continuous interface monitoring and concentration measurements were made to observe developments of instabilities and their effects on the removal of sediment. Floc size was measured during the experiments using a floc camera and image analysis routines. This presentation will provide an overview of the stagnant tank experiments, but will focus on results from the stratified flume experiments and an analysis that attempts to synthesizes the results from the entirety of the study. The results from the stratified flume experiments show that under shear instabilities, the effective settling velocity is greater than the floc settling velocity, and that the rate increases with plume velocity and interface mixing. The difference between effective and floc settling velocity was denoted as the shear-induced settling velocity. This rate was found to be a strong function of the Richardson number, and was attributed to mixing processes at the interface. Conceptual and empirical analysis shows that the shear-induced settling velocity is proportional to URi-2. The resulting effective settling velocity models developed from these experiments are then used to examine the rates and potential locations of operations of these mechanism over the length of a river mouth plume.

  20. Benchmarking of electrolyte mass transport in next generation lithium batteries

    Directory of Open Access Journals (Sweden)

    Jonas Lindberg

    2017-12-01

    Full Text Available Beyond conductivity and viscosity, little is often known about the mass transport properties of next generation lithium battery electrolytes, thus, making performance estimation uncertain when concentration gradients are present, as conductivity only describes performance in the absence of these gradients. This study experimentally measured the diffusion resistivity, originating from voltage loss due to a concentration gradient, together with the ohmic resistivity, obtained from ionic conductivity measurements, hence, evaluating electrolytes both with and without the presence of concentration gradients. Under galvanostatic conditions, the concentration gradients, of all electrolytes examined, developed quickly and the diffusion resistivity rapidly dominated the ohmic resistivity. The electrolytes investigated consisted of lithium salt in: room temperature ionic liquids (RTIL, RTIL mixed organic carbonates, dimethyl sulfoxide (DMSO, and a conventional Li-ion battery electrolyte. At steady state the RTIL electrolytes displayed a diffusion resistivity ~ 20 times greater than the ohmic resistivity. The DMSO-based electrolyte showed mass transport properties similar to the conventional Li-ion battery electrolyte. In conclusion, the results presented in this study show that the diffusion polarization must be considered in applications where high energy and power density are desired.

  1. Dusty air masses transport between Amazon Basin and Caribbean Islands

    Science.gov (United States)

    Euphrasie-Clotilde, Lovely; Molinie, Jack; Prospero, Joseph; Feuillard, Tony; Brute, Francenor; Jeannot, Alexis

    2015-04-01

    Depend on the month, African desert dust affect different parts of the North Atlantic Ocean. From December to April, Saharan dust outbreaks are often reported over the amazon basin and from May to November over the Caribbean islands and the southern regions of USA. This annual oscillation of Saharan dust presence, related to the ITCZ position, is perturbed some time, during March. Indeed, over Guadeloupe, the air quality network observed between 2007 and 2012 several dust events during March. In this paper, using HISPLIT back trajectories, we analyzed air masses trajectories for March dust events observed in Guadeloupe, from 2007 to 2012.We observed that the high pressure positions over the Atlantic Ocean allow the transport of dusty air masses from southern region of West Africa to the Caribbean Sea with a path crossing close to coastal region of French Guyana. Complementary investigations including the relationship between PM10 concentrations recorded in two sites Pointe-a-Pitre in the Caribbean, and Cayenne in French Guyana, have been done. Moreover we focus on the mean delay observed between the times arrival. All the results show a link between pathway of dusty air masses present over amazon basin and over the Caribbean region during several event of March. The next step will be the comparison of mineral dust composition for this particular month.

  2. Organic Spin-Valves and Beyond: Spin Injection and Transport in Organic Semiconductors and the Effect of Interfacial Engineering.

    Science.gov (United States)

    Jang, Hyuk-Jae; Richter, Curt A

    2017-01-01

    Since the first observation of the spin-valve effect through organic semiconductors, efforts to realize novel spintronic technologies based on organic semiconductors have been rapidly growing. However, a complete understanding of spin-polarized carrier injection and transport in organic semiconductors is still lacking and under debate. For example, there is still no clear understanding of major spin-flip mechanisms in organic semiconductors and the role of hybrid metal-organic interfaces in spin injection. Recent findings suggest that organic single crystals can provide spin-transport media with much less structural disorder relative to organic thin films, thus reducing momentum scattering. Additionally, modification of the band energetics, morphology, and even spin magnetic moment at the metal-organic interface by interface engineering can greatly impact the efficiency of spin-polarized carrier injection. Here, progress on efficient spin-polarized carrier injection into organic semiconductors from ferromagnetic metals by using various interface engineering techniques is presented, such as inserting a metallic interlayer, a molecular self-assembled monolayer (SAM), and a ballistic carrier emitter. In addition, efforts to realize long spin transport in single-crystalline organic semiconductors are discussed. The focus here is on understanding and maximizing spin-polarized carrier injection and transport in organic semiconductors and insight is provided for the realization of emerging organic spintronics technologies. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Pulsed Electrochemical Mass Spectrometry for Operando Tracking of Interfacial Processes in Small-Time-Constant Electrochemical Devices such as Supercapacitors.

    Science.gov (United States)

    Batisse, Nicolas; Raymundo-Piñero, Encarnación

    2017-11-29

    A more detailed understanding of the electrode/electrolyte interface degradation during the charging cycle in supercapacitors is of great interest for exploring the voltage stability range and therefore the extractable energy. The evaluation of the gas evolution during the charging, discharging, and aging processes is a powerful tool toward determining the stability and energy capacity of supercapacitors. Here, we attempt to fit the gas analysis resolution to the time response of a low-gas-generation power device by adopting a modified pulsed electrochemical mass spectrometry (PEMS) method. The pertinence of the method is shown using a symmetric carbon/carbon supercapacitor operating in different aqueous electrolytes. The differences observed in the gas levels and compositions as a function of the cell voltage correlate to the evolution of the physicochemical characteristics of the carbon electrodes and to the electrochemical performance, giving a complete picture of the processes taking place at the electrode/electrolyte interface.

  4. Simulation study of the effect of molar mass dispersity on domain interfacial roughness in lamellae forming block copolymers for directed self-assembly

    International Nuclear Information System (INIS)

    Peters, Andrew J; Lawson, Richard A; Nation, Benjamin D; Ludovice, Peter J; Henderson, Clifford L

    2015-01-01

    A coarse-grained molecular dynamics model was used to study the thin film self-assembly and resulting pattern properties of block copolymer (BCP) systems with various molar mass dispersities. Diblock copolymers (i.e. A–b–B type) were simulated in an aligned lamellar state, which is one of the most common patterns of potential use for integrated circuit fabrication via directed self-assembly of BCPs. Effects of the molar mass dispersity (Ð) on feature pitch and interfacial roughness, which are critical lithographic parameters that have a direct impact on integrated circuit performance, were simulated. It was found that for a realistic distribution of polymer molecular weights, modeled by a Wesslau distribution, both line edge roughness (LER) and line width roughness (LWR) increase approximately linearly with increasing Ð, up to ∼45% of the monodisperse value at Ð = 1.5. Mechanisms of compensation for increased A–A and B–B roughness were considered. It was found that long and short chain positions were not correlated, and that long chains were significantly deformed in shape. The increase in LWR was due to the increase in LER and a constant correlation between the line edges. Unaligned systems show a correlation between domain width and local molecular weight, while systems aligned on an alternating pattern of A and B lines did not show any correlation. When the volume fraction of individual chains was allowed to vary, similar results were found when considering the Ð of the block as opposed to the Ð of the entire system. (paper)

  5. Interfacial heat transfer - State of the art

    International Nuclear Information System (INIS)

    Yadigaroglu, G.

    1987-01-01

    Interfacial heat exchanges control the interfacial mass exchange rate, depend on the interfacial area, and are tied to the prediction of thermal nonequilibrium. The nature of the problem usually requires the formulation of mechanistic laws and precludes the general use of universal correlations. This is partly due to the fact that the length scale controlling the interfacial exchanges varies widely from one situation to another and has a strong influence on the exchange coefficients. Within the framework of the ''two-fluid models'', the exchanges occurring at the interfaces are explicitly taken into consideration by the jump condition linking the volumetric mass exchange (evaporation) rate between the phases, to the interfacial energy transfer rates

  6. Irradiation-enhanced and-induced mass transport

    International Nuclear Information System (INIS)

    Rehn, L.E.

    1989-01-01

    Irradiation can be used to enhance diffusion, that is, to increase the rate at which equilibrium is attained, as well as to induce nonequilibrium changes. The main factors influencing whether irradiation will drive a material toward or away from equilibrium are the initial specimen microstructure and geometry, irradiation temperature, and primary recoil spectrum. This paper summarizes known effects of irradiation temperature and primary recoil spectrum on mass transport during irradiation. In comparison to either electron or heavy-ion irradiation, it is concluded that relatively low-energy, light-ion bombardment at intermediate temperatures offers the greatest potential to enhance the rate at which equilibrium is attained. The greatest departures from equilibrium can be expected from irradiation with similar particles at very low temperatures

  7. Mass transport of soluble species through backfill into surrounding rock

    International Nuclear Information System (INIS)

    Kang, Chul Hyung; Park, Hun Hwee

    1992-01-01

    Some soluble species may not be solubility-limited or congruent-released with the matrix species. For example, during the operation of the nuclear reactor, the fission products can be accumulated in the fuel-cladding gap, void, and grain boundaries of the fuel rods. In the waste package for spent-fuel placed in a geologic repository, the high solubility species of these fission products accumulated in the 'gap', e.g. cesium or iodine are expected to dissolve rapidly when ground water penetrates fuel rods. The time and space dependent mass transport for high solubility nuclides in the gap is analyzed, and its numerical illustrations are demonstrated. The approximate solution that is valid for all times is developed, and validated by comparison with an asymptotic solution and the solution obtained by the numerical inversion of Laplace transform covering the entire time span. (Author)

  8. Chemistry and mass transport of iodine in containment

    International Nuclear Information System (INIS)

    Beahm, E.C.; Weber, C.F.; Kress, T.S.; Shockley, W.E.; Daish, S.R.

    1988-01-01

    TRENDS is a computer code for modeling behavior of iodine in containment. It tracks both chemical and physical changes and features such as calculation of radiation dose rates in water pools , radiolysis effects, hydrolysis, and deposition/revaporization on aerosols and structural surfaces. Every attempt has been made to account for all significant processes. Reaction rate constants for iodine hydrolysis and radiolysis were obtained by a variable algorithm that gives values closely modeling experimental data. TRENDS output provides the distribution of iodine in containment and release from containment as a function of time during a severe accident sequence. Initial calculations with TRENDS have shown that the amount of volatile iodine released from containment is sensitive to the value of the liquid-gas (evaporation) mass transport coefficient for I 2 . 7 refs., 4 figs., 3 tabs

  9. A Coupled Chemical and Mass Transport Model for Concrete Durability

    DEFF Research Database (Denmark)

    Jensen, Mads Mønster; Johannesson, Björn; Geiker, Mette Rica

    2012-01-01

    -Raphson iteration scheme arising from the non-linearity. The overall model is a transient problem, solved using a single parameter formulation. The sorption hysteresis and chemical equilibrium is included as source or sink terms. The advantages with this formulation is that each node in the discrete system has...... their individual sorption hysteresis isotherm which is of great importance when describing non fully water saturated system e.g. caused by time depended boundary conditions. Chemical equilibrium is also established in each node of the discrete system, where the rate of chemical degradation is determined.......g. charge balance, from the mass transport calculation could cause the above mentioned numerical problems. Two different test cases are studied, the sorption hysteresis in different depth of the sample, caused by time depended boundary condition and the chemical degradation of the solid matrix in a ten year...

  10. Mass transport measurements and modeling for chemical vapor infiltration

    Energy Technology Data Exchange (ETDEWEB)

    Starr, T.L.; Chiang, D.Y.; Fiadzo, O.G.; Hablutzel, N. [Georgia Inst. of Tech., Atlanta, GA (United States). School of Materials Science and Engineering

    1997-12-01

    This project involves experimental and modeling investigation of densification behavior and mass transport in fiber preforms and partially densified composites, and application of these results to chemical vapor infiltration (CVI) process modeling. This supports work on-going at ORNL in process development for fabrication of ceramic matrix composite (CMC) tubes. Tube-shaped composite preforms are fabricated at ORNL with Nextel{trademark} 312 fiber (3M Corporation, St. Paul, MN) by placing and compressing several layers of braided sleeve on a tubular mandrel. In terms of fiber architecture these preforms are significantly different than those made previously with Nicalon{trademark} fiber (Nippon Carbon Corp., Tokyo, Japan) square weave cloth. The authors have made microstructure and permeability measurements on several of these preforms and a few partially densified composites so as to better understand their densification behavior during CVI.

  11. Two-Step Physical Deposition of a Compact CuI Hole-Transport Layer and the Formation of an Interfacial Species in Perovskite Solar Cells.

    Science.gov (United States)

    Gharibzadeh, Saba; Nejand, Bahram Abdollahi; Moshaii, Ahmad; Mohammadian, Nasim; Alizadeh, Amir Hossein; Mohammadpour, Rahele; Ahmadi, Vahid; Alizadeh, Abdolali

    2016-08-09

    A simple and practical approach is introduced for the deposition of CuI as an inexpensive inorganic hole-transport material (HTM) for the fabrication of low cost perovskite solar cells (PSCs) by gas-solid phase transformation of Cu to CuI. The method provides a uniform and well-controlled CuI layer with large grains and good compactness that prevents the direct connection between the contact electrodes. Solar cells prepared with CuI as the HTM with Au electrodes displays an exceptionally high short-circuit current density of 32 mA cm(-2) , owing to an interfacial species formed between the perovskite and the Cu resulting in a long wavelength contribution to the incident photon-to-electron conversion efficiency (IPCE), and an overall power conversion efficiency (PCE) of 7.4 %. The growth of crystalline and uniform CuI on a low roughness perovskite layer leads to remarkably high charge extraction in the cells, which originates from the high hole mobility of CuI in addition to a large number of contact points between CuI and the perovskite layer. In addition, the solvent-free method has no damaging side effect on the perovskite layer, which makes it an appropriate method for large scale applications of CuI in perovskite solar cells. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Materials with engineered mesoporosity for programmed mass transport

    Science.gov (United States)

    Gough, Dara V.

    Transport in nanostructured materials is of great interest for scientists in various fields, including molecular sequestration, catalysis, artificial photosynthesis and energy storage. This thesis will present work on the transport of molecular and ionic species in mesoporous materials (materials with pore sizes between 2 and 50 nm). Initially, discussion will focus on the synthesis of mesoporous ZnS nanorattles and the size selected mass transport of small molecules through the mesopores. Discussion will then shift of exploration of cation exchange and electroless plating of metals to alter the mesoporous hollow sphere (MHS) materials and properties. The focus of discussion will then shift to the transport of ions into and out of a hierarchically structured gold electrode. Finally, a model gamma-bactiophage was developed to study the electromigration of charged molecules into and out of a confined geometry. A catalytically active biomolecular species was encapsulated within the central cavity of ZnS MHS. Both the activity of the encapsulated enzyme and the size-selective transport through the wall of the MHS were verified through the use of a common fluorogen, hydrogen peroxide, and sodium azide. Additionally, the protection of the enzyme was shown through size-selected blocking of a protease. The mesoporous hollow sphere system introduces size-selectivity to catalyzed chemical reactions; future work may include variations in pore sizes, and pore wall chemical functionalization. The pore size in ZnS mesoporous hollow spheres is controlled between 2.5 and 4.1 nm through swelling of the lyotropic liquid crystal template. The incorporation of a swelling agent is shown to linearly vary the hexagonal lyotropic liquid crystalline phase, which templates the mesopores, while allowing the high fidelity synthesis of mesoporous hollow spheres. Fluorescnently labeled ssDNA was utilized as a probe to explore the change in mesopore permeability afforded by the swollen template

  13. Mass and charge transport in IPMC actuators with fractal interfaces

    Science.gov (United States)

    Chang, Longfei; Wu, Yucheng; Zhu, Zicai; Li, Heng

    2016-04-01

    Ionic Polymer-Metal Composite (IPMC) actuators have been attracting a growing interest in extensive applications, which consequently raises the demands on the accuracy of its theoretical modeling. For the last few years, rough landscape of the interface between the electrode and the ionic membrane of IPMC has been well-documented as one of the key elements to ensure a satisfied performance. However, in most of the available work, the interface morphology of IPMC was simplified with structural idealization, which lead to perplexity in the physical interpretation on its interface mechanism. In this paper, the quasi-random rough interface of IPMC was described with fractal dimension and scaling parameters. And the electro-chemical field was modeled by Poisson equation and a properly simplified Nernst-Planck equation set. Then, by simulation with Finite Element Method, a comprehensive analysis on he inner mass and charge transportation in IPMC actuators with different fractal interfaces was provided, which may be further adopted to instruct the performance-oriented interface design for ionic electro-active actuators. The results also verified that rough interface can impact the electrical and mechanical response of IPMC, not only from the respect of the real surface increase, but also from mass distribution difference caused by the complexity of the micro profile.

  14. Monoporous micropillar wick structures, I-Mass transport characteristics

    International Nuclear Information System (INIS)

    Ravi, Saitej; Horner, David; Moghaddam, Saeed

    2014-01-01

    This paper is the first of a two-part study concerning the relation between the geometry of micropillar array wicks and their thermohydraulic performance. In this paper, a parametric study of pillar array geometries is conducted, and the efficacies of existing capillary pressure and permeability models in predicting the experimental results are examined. A new method is utilized to independently measure the permeability and capillary pressure of a wick structure. A permeability model based on creeping flow past infinitely long cylinders, corrected to account for the effect of meniscus curvature on mass flow rate through pillar arrays with a limited height, closely predicts the experimental data. Also, a model that relates the capillary pressure to the wick geometry using a thermodynamic approach better predicts the experimental results. The approach adopted by this model involves using a surface energy minimization algorithm to determine the shape of the meniscus within the pillars. These permeability and capillary pressure models were coupled with Darcy's law for fluid flow to obtain an overall expression for flow through micropillar arrays. The overall model is utilized in the second part of this study to determine optimized micropillar wick geometries and the theoretical limits of their performance. - Highlights: • New method for independent measurement of capillary pressure and permeability. • Validated various capillary pressure and permeability models from literature. • Overall model to characterize mass transport capacity of micropillar arrays

  15. Dynamic characterization of external and internal mass transport in heterotrophic biofilms from microsensors measurements.

    Science.gov (United States)

    Guimerà, Xavier; Dorado, Antonio David; Bonsfills, Anna; Gabriel, Gemma; Gabriel, David; Gamisans, Xavier

    2016-10-01

    Knowledge of mass transport mechanisms in biofilm-based technologies such as biofilters is essential to improve bioreactors performance by preventing mass transport limitation. External and internal mass transport in biofilms was characterized in heterotrophic biofilms grown on a flat plate bioreactor. Mass transport resistance through the liquid-biofilm interphase and diffusion within biofilms were quantified by in situ measurements using microsensors with a high spatial resolution (mass transport coefficients. The sensitivity of external and internal mass transport resistances to flow conditions within the range of typical fluid velocities over biofilms (Reynolds numbers between 0.5 and 7) was assessed. Estimated external mass transfer coefficients at different liquid phase flow velocities showed discrepancies with studies considering laminar conditions in the diffusive boundary layer near the liquid-biofilm interphase. The correlation of effective diffusivity with flow velocities showed that the heterogeneous structure of biofilms defines the transport mechanisms inside biofilms. Internal mass transport was driven by diffusion through cell clusters and aggregates at Re below 2.8. Conversely, mass transport was driven by advection within pores, voids and water channels at Re above 5.6. Between both flow velocities, mass transport occurred by a combination of advection and diffusion. Effective diffusivities estimated at different biofilm densities showed a linear increase of mass transport resistance due to a porosity decrease up to biofilm densities of 50 g VSS·L(-1). Mass transport was strongly limited at higher biofilm densities. Internal mass transport results were used to propose an empirical correlation to assess the effective diffusivity within biofilms considering the influence of hydrodynamics and biofilm density. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Cerebrospinal and interstitial fluid transport via the glymphatic pathway modeled by optimal mass transport.

    Science.gov (United States)

    Ratner, Vadim; Gao, Yi; Lee, Hedok; Elkin, Rena; Nedergaard, Maiken; Benveniste, Helene; Tannenbaum, Allen

    2017-05-15

    The glymphatic pathway is a system which facilitates continuous cerebrospinal fluid (CSF) and interstitial fluid (ISF) exchange and plays a key role in removing waste products from the rodent brain. Dysfunction of the glymphatic pathway may be implicated in the pathophysiology of Alzheimer's disease. Intriguingly, the glymphatic system is most active during deep wave sleep general anesthesia. By using paramagnetic tracers administered into CSF of rodents, we previously showed the utility of MRI in characterizing a macroscopic whole brain view of glymphatic transport but we have yet to define and visualize the specific flow patterns. Here we have applied an alternative mathematical analysis approach to a dynamic time series of MRI images acquired every 4min over ∼3h in anesthetized rats, following administration of a small molecular weight paramagnetic tracer into the CSF reservoir of the cisterna magna. We use Optimal Mass Transport (OMT) to model the glymphatic flow vector field, and then analyze the flow to find the network of CSF-ISF flow channels. We use 3D visualization computational tools to visualize the OMT defined network of CSF-ISF flow channels in relation to anatomical and vascular key landmarks from the live rodent brain. The resulting OMT model of the glymphatic transport network agrees largely with the current understanding of the glymphatic transport patterns defined by dynamic contrast-enhanced MRI revealing key CSF transport pathways along the ventral surface of the brain with a trajectory towards the pineal gland, cerebellum, hypothalamus and olfactory bulb. In addition, the OMT analysis also revealed some interesting previously unnoticed behaviors regarding CSF transport involving parenchymal streamlines moving from ventral reservoirs towards the surface of the brain, olfactory bulb and large central veins. Copyright © 2017. Published by Elsevier Inc.

  17. Interfacial microstructure and shear strength of reactive air brazed oxygen transport membrane ceramic-metal alloy joints

    Science.gov (United States)

    FR, Wahid Muhamad; Yoon, Dang-Hyok; Raju, Kati; Kim, Seyoung; Song, Kwang-sup; Yu, Ji Haeng

    2018-01-01

    To fabricate a multi-layered structure for maximizing oxygen production, oxygen transport membrane (OTM) ceramics need to be joined or sealed hermetically metal supports for interfacing with the peripheral components of the system. Therefore, in this study, Ag-10 wt% CuO was evaluated as an effective filler material for the reactive air brazing of dense Ce0.9Gd0.1O2-δ-La0.7Sr0.3MnO3±δ (GDC-LSM) OTM ceramics. Thermal decomposition in air and wetting behavior of the braze filler was performed. Reactive air brazing was performed at 1050 °C for 30 min in air to join GDC-LSM with four different commercially available high temperature-resistant metal alloys, such as Crofer 22 APU, Inconel 600, Fecralloy, and AISI 310S. The microstructure and elemental distribution of the ceramic-ceramic and ceramic-metal interfaces were examined from polished cross-sections. The mechanical shear strength at room temperature for the as-brazed and isothermally aged (800 °C for 24 h) joints of all the samples was compared. The results showed that the strength of the ceramic-ceramic joints was decreased marginally by aging; however, in the case of metal-ceramic joints, different decreases in strengths were observed according to the metal alloy used, which was explained based on the formation of different oxide layers at the interfaces.

  18. The latent fingerprint in mass transport of polycrystalline materials

    Science.gov (United States)

    Thirunavukarasu, Gopinath; Kundu, Sukumar; Chatterjee, Subrata

    2016-02-01

    Herein, a systematic investigation was carried out to reach a rational understanding and to provide information concerning the possible causes for a significant influence of pressure variation in the underlying processes of mass transport in polycrystalline materials. The authors focused their research in solid-state diffusion, a part of the subject "Mass Transport in Solids". Theories on diffusion are the subject by itself which exists as a latent fingerprint in every text of higher learning in interdisciplinary science. In this research, authors prepared sandwich samples of titanium alloy and stainless steel using nickel as an intermediate metal. The samples were processed at three different levels of bonding pressure (3, 4 and 5 MPa) while bonding temperature and bonding time was maintained at 750 °C and 1 h, respectively, throughout the experiments. It was observed that the net flux of atomic diffusion of nickel atoms into Ti-alloy at TiA/Ni interface increased by ~63 % with the rise in the bonding pressure from 3 to 4 MPa, but decreased by ~40 % with the rise in the bonding pressure from 4 to 5 MPa. At the same time, the net flux of atomic diffusion of nickel atoms into stainless steel at Ni/SS interface increased by ~19 % with the rise in the bonding pressure from 3 to 4 MPa, but increased by ~17 % with the rise in the bonding pressure from 4 to 5 MPa. Here authors showed that the pressure variations have different effects at the TiA/Ni interface and Ni/SS interface, and tried to explain the explicit mechanisms operating behind them. In general for sandwich samples processed irrespective of bonding pressure chosen, the net flux of Ni-atoms diffused into SS is greater than that of the net flux of Ni-atoms diffused in Ti-alloy matrix by four orders of magnitude. The calculated diffusivity of Ni-atoms into Ti-alloy reaches its highest value of ~5.083 × 10-19 m2/s for the sandwich sample processed using 4-MPa bonding-pressure, whereas the diffusivity of Ni

  19. Interfacial phenomenon theory

    International Nuclear Information System (INIS)

    Kim, Jong Deuk

    2000-02-01

    This book is composed of 8 chapters. It tells what interfacial phenomenon is by showing interfacial energy, characteristic of interface and system of interface from chapter 1. It also introduces interfacial energy and structure theory, molecular structure and orientation theory, and interfacial electricity phenomenon theory in the following 3 chapters. It still goes on by introducing super molecule cluster, disequilibrium dispersion, and surface and film through 3 chapters. And the last chapter is about colloid and application of interface.

  20. Multiscale modeling of fluid flow and mass transport

    Science.gov (United States)

    Masuoka, K.; Yamamoto, H.; Bijeljic, B.; Lin, Q.; Blunt, M. J.

    2017-12-01

    In recent years, there are some reports on a simulation of fluid flow in pore spaces of rocks using Navier-Stokes equations. These studies mostly adopt a X-ray CT to create 3-D numerical grids of the pores in micro-scale. However, results may be of low accuracy when the rock has a large pore size distribution, because pores, whose size is smaller than resolution of the X-ray CT may be neglected. We recently found out by tracer tests in a laboratory using a brine saturated Ryukyu limestone and inject fresh water that a decrease of chloride concentration took longer time. This phenomenon can be explained due to weak connectivity of the porous networks. Therefore, it is important to simulate entire pore spaces even those of very small sizes in which diffusion is dominant. We have developed a new methodology for multi-level modeling for pore scale fluid flow in porous media. The approach is to combine pore-scale analysis with Darcy-flow analysis using two types of X-ray CT images in different resolutions. Results of the numerical simulations showed a close match with the experimental results. The proposed methodology is an enhancement for analyzing mass transport and flow phenomena in rocks with complicated pore structure.

  1. Analysis of diffusive mass transport in a cracked buffer

    International Nuclear Information System (INIS)

    Garisto, N.C.; Garisto, F.

    1989-11-01

    In the disposal vault design for the Canadian Nuclear Fuel Waste Management Program, cylindrical containers of used nuclear fuel would be placed in vertical boreholes in rock and surrounded with a bentonite-based buffer material. The buffer is expected to absorb and/or retard radionuclides leaching from the fuel after the containers fail. There is some evidence, however, that the buffer may be susceptible to cracking. In this report we investigate numerically the consequences of cracking on uranium diffusion through the buffer. The derivation of the mass-transport equations and the numerical solution method are presented for the solubility-limited diffusion of uranium in a cracked buffer system for both swept-away and semi-impermeable boundary conditions at the rock-buffer interface. The results indicate that for swept-away boundary conditions the total uranium flux through the cracked buffer system is, as expected, greater than through the uncracked buffer. The effect of the cracks is strongly dependent on the ratio D/D eff , where D and D eff are the pore-water and the effective buffer diffusion coefficient, respectively. However, although a decrease in D eff enhances the effect of cracks on the total cumulative flux (relative to the uncracked buffer), it also decreases the total cumulative flux through the cracked buffer system (relative to a cracked buffer with a larger D eff value). Finally, for semi-impermeable boundary conditions, the effect of cracks on the total radionuclide flux is relatively small

  2. Incorporating interfacial phenomena in solidification models

    Science.gov (United States)

    Beckermann, Christoph; Wang, Chao Yang

    1994-01-01

    A general methodology is available for the incorporation of microscopic interfacial phenomena in macroscopic solidification models that include diffusion and convection. The method is derived from a formal averaging procedure and a multiphase approach, and relies on the presence of interfacial integrals in the macroscopic transport equations. In a wider engineering context, these techniques are not new, but their application in the analysis and modeling of solidification processes has largely been overlooked. This article describes the techniques and demonstrates their utility in two examples in which microscopic interfacial phenomena are of great importance.

  3. Establishing a Quantitative Functional Relationship between Capillary Pressure Saturation and Interfacial Area; FINAL

    International Nuclear Information System (INIS)

    Carlo Montemagno

    2002-01-01

    We propose to continue our collaborative research focused on advanced technologies for subsurface contamination problems. Our approach combines new multi-phase flow theory, novel laboratory experiments, and non-traditional computational simulators to investigate practical approaches to include interfacial areas in descriptions of subsurface contaminant transport and remediation. Because all inter-phase mass transfer occurs at fluid-fluid interfaces, and it is this inter-phase mass transfer that leads to the difficult, long-term ground-water contamination problems, it is critical to include interfacial behavior in the problem description. This is currently lacking in all standard models of complex ground-water contamination problems. In our earlier project, we developed tools appropriate for inclusion of interfacial areas under equilibrium conditions. These include advanced laboratory techniques and targeted computational experiments that validated certain key theoretical conjecture s. However, it has become clear that to include interfacial behavior fully into a description of the multi-phase flow and contamination problems, the fully dynamic case must be considered. Therefore, we need to develop both experimental and computational tools that can capture the dynamic nature of interfacial movements. Development and application of such tools will allow the theory to be evaluated, and will lead to significant improvements in our understanding of complex subsurface contamination problems, thereby allowing us to develop and evaluate improved remediation technologies

  4. Establishing a Quantitative Functional Relationship between Capillary Pressure Saturation and Interfacial Area

    International Nuclear Information System (INIS)

    Carlo Montemagno

    2002-01-01

    We propose to continue our collaborative research focused on advanced technologies for subsurface contamination problems. Our approach combines new multi-phase flow theory, novel laboratory experiments, and non-traditional computational simulators to investigate practical approaches to include interfacial areas in descriptions of subsurface contaminant transport and remediation. Because all inter-phase mass transfer occurs at fluid-fluid interfaces, and it is this inter-phase mass transfer that leads to the difficult, long-term ground-water contamination problems, it is critical to include interfacial behavior in the problem description. This is currently lacking in all standard models of complex ground-water contamination problems. In our earlier project, we developed tools appropriate for inclusion of interfacial areas under equilibrium conditions. These include advanced laboratory techniques and targeted computational experiments that validated certain key theoretical conjecture s. However, it has become clear that to include interfacial behavior fully into a description of the multi-phase flow and contamination problems, the fully dynamic case must be considered. Therefore, we need to develop both experimental and computational tools that can capture the dynamic nature of interfacial movements. Development and application of such tools will allow the theory to be evaluated, and will lead to significant improvements in our understanding of complex subsurface contamination problems, thereby allowing us to develop and evaluate improved remediation technologies

  5. Transport and mass exchange processes in sand and gravel aquifers (v.1)

    International Nuclear Information System (INIS)

    Moltyaner, G.

    1990-01-01

    The objectives of this conference were to exchange information on promising field measurement techniques used for the characterization of spatial variability of geologic formations and on new methods used for quantifying the effect of spatial variability on groundwater flow and transport of materials; to discuss novel developments in the theory of transport processes and simulation methods; and to present views and opinions on future initiatives and directions in the design of large-scale field tracer experiments and the development of conceptual and mathematical models of transport and mass exchange processes. The 46 papers presented in these proceedings are divided into six sections: field studies of transport processes; groundwater tracers and novel field measurement techniques; promising methods and field measurement techniques for quantifying the effect of geological heterogeneities on groundwater flow and transport; novel developments in the theory of transport processes; numerical modelling of transport and mass exchange processes; and field and modelling studies of mass exchange processes. (L.L.)

  6. Three-dimensional two-phase mass transport model for direct methanol fuel cells

    International Nuclear Information System (INIS)

    Yang, W.W.; Zhao, T.S.; Xu, C.

    2007-01-01

    A three-dimensional (3D) steady-state model for liquid feed direct methanol fuel cells (DMFC) is presented in this paper. This 3D mass transport model is formed by integrating five sub-models, including a modified drift-flux model for the anode flow field, a two-phase mass transport model for the porous anode, a single-phase model for the polymer electrolyte membrane, a two-phase mass transport model for the porous cathode, and a homogeneous mist-flow model for the cathode flow field. The two-phase mass transport models take account the effect of non-equilibrium evaporation/ condensation at the gas-liquid interface. A 3D computer code is then developed based on the integrated model. After being validated against the experimental data reported in the literature, the code was used to investigate numerically transport behaviors at the DMFC anode and their effects on cell performance

  7. Interfacial effects in multilayers

    International Nuclear Information System (INIS)

    Barbee, T.W. Jr.

    1998-01-01

    Interfacial structure and the atomic interactions between atoms at interfaces in multilayers or nano-laminates have significant impact on the physical properties of these materials. A technique for the experimental evaluation of interfacial structure and interfacial structure effects is presented and compared to experiment. In this paper the impact of interfacial structure on the performance of x-ray, soft x-ray and extreme ultra-violet multilayer optic structures is emphasized. The paper is concluded with summary of these results and an assessment of their implications relative to multilayer development and the study of buried interfaces in solids in general

  8. Interfacial area and interfacial transfer in two-phase systems. DOE final report

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, Mamoru; Hibiki, T.; Revankar, S.T.; Kim, S.; Le Corre, J.M.

    2002-07-01

    In the two-fluid model, the field equations are expressed by the six conservation equations consisting of mass, momentum and energy equations for each phase. The existence of the interfacial transfer terms is one of the most important characteristics of the two-fluid model formulation. The interfacial transfer terms are strongly related to the interfacial area concentration and to the local transfer mechanisms such as the degree of turbulence near interfaces. This study focuses on the development of a closure relation for the interfacial area concentration. A brief summary of several problems of the current closure relation for the interfacial area concentration and a new concept to overcome the problem are given.

  9. Thickness Optimisation of Textiles Subjected to Heat and Mass Transport during Ironing

    Directory of Open Access Journals (Sweden)

    Korycki Ryszard

    2016-09-01

    Full Text Available Let us next analyse the coupled problem during ironing of textiles, that is, the heat is transported with mass whereas the mass transport with heat is negligible. It is necessary to define both physical and mathematical models. Introducing two-phase system of mass sorption by fibres, the transport equations are introduced and accompanied by the set of boundary and initial conditions. Optimisation of material thickness during ironing is gradient oriented. The first-order sensitivity of an arbitrary objective functional is analysed and included in optimisation procedure. Numerical example is the thickness optimisation of different textile materials in ironing device.

  10. A mass conservative numerical solution of vertical water flow and mass transport equations in unsaturated porous media

    International Nuclear Information System (INIS)

    Lim, S.C.; Lee, K.J.

    1993-01-01

    The Galerkin finite element method is used to solve the problem of one-dimensional, vertical flow of water and mass transport of conservative-nonconservative solutes in unsaturated porous media. Numerical approximations based on different forms of the governing equation, although they are equivalent in continuous forms, can result in remarkably different solutions in an unsaturated flow problem. Solutions given by a simple Galerkin method based on the h-based Richards equation yield a large mass balance error and an underestimation of the infiltration depth. With the employment of the ROMV (restoration of main variable) concept in the discretization step, the mass conservative numerical solution algorithm for water flow has been derived. The resulting computational schemes for water flow and mass transport are applied to sandy soil. The ROMV method shows good mass conservation in water flow analysis, whereas it seems to have a minor effect on mass transport. However, it may relax the time-step size restriction and so ensure an improved calculation output. (author)

  11. FEFLOW finite element modeling of flow, mass and heat transport in porous and fractured media

    CERN Document Server

    Diersch, Hans-Jörg G

    2013-01-01

    Placing advanced theoretical and numerical methods in the hands of modeling practitioners and scientists, this book explores the FEFLOW system for solving flow, mass and heat transport processes in porous and fractured media. Offers applications and exercises.

  12. Multiple nucleon transfer in damped nuclear collisions. [Lectures, mass charge, and linear and angular momentum transport

    Energy Technology Data Exchange (ETDEWEB)

    Randrup, J.

    1979-07-01

    This lecture discusses a theory for the transport of mass, charge, linear, and angular momentum and energy in damped nuclear collisions, as induced by multiple transfer of individual nucleons. 11 references.

  13. The effect of mass transport on the graphite/CO2 reaction

    International Nuclear Information System (INIS)

    Stephen, W.J.

    1984-11-01

    The Graphite/CO 2 reaction is strongly inhibited by the reaction product CO and therefore any model for the influence of mass transport on reaction rate should consider this. The problem of internal mass transport alone has been considered in previous notes. This note extends the models to include external mass transport. Results are compared with simple first order reaction with no volume change. The calculations demonstrate that, for strong CO inhibition, external mass transport limits reaction at a much lower rate than for first order kinetics and that the usual concept of three reaction zones corresponding to chemical control, in-pore diffusion control and boundary layer control can be unrealistically idealised. (U.K.)

  14. Solvable Model for Dynamic Mass Transport in Disordered Geophysical Media

    KAUST Repository

    Marder, M.; Eftekhari, Behzad; Patzek, Tadeusz

    2018-01-01

    We present an analytically solvable model for transport in geophysical materials on large length and time scales. It describes the flow of gas to a complicated absorbing boundary over long periods of time. We find a solution to this model using Green's function techniques, and apply the solution to three absorbing networks of increasing complexity.

  15. Solvable Model for Dynamic Mass Transport in Disordered Geophysical Media

    KAUST Repository

    Marder, M.

    2018-03-29

    We present an analytically solvable model for transport in geophysical materials on large length and time scales. It describes the flow of gas to a complicated absorbing boundary over long periods of time. We find a solution to this model using Green\\'s function techniques, and apply the solution to three absorbing networks of increasing complexity.

  16. Study on flow and mass transport through fractured soft sedimentary rocks (Contact research)

    International Nuclear Information System (INIS)

    Shimo, Michito; Kumamoto, Sou; Maekawa, Keisuke

    2007-03-01

    It is important for safety assessment of HLW geological disposal to evaluate groundwater flow and mass transport in deep underground accurately. Though it is considered that the mass transport in sedimentary rock occurs in pores between grains mainly, fractures of sedimentary rock can be main paths. The objective of this study is to establish a conceptual model for flow and mass transport in fractured soft sedimentary rock. In previous study, a series of laboratory hydraulic and tracer tests and numerical analyses were carried out using sedimentary rock specimens obtained from Koetoi and Wakkanai formation. Single natural fractured cores and rock block specimen were used for the tests and analyses. The results indicated that the matrix diffusion played an important role for mass transport in the fractured soft sedimentary rocks. In this study, the following two tasks were carried out: (1) laboratory hydraulic and tracer experiments of rock cores of Koetoi and Wakkanai formation obtained at HDB-9, HDB-10 and HDB-11 boreholes and a rock block specimen, Wakkanai formation, obtained at an outcrop in the Horonobe area, (2) a numerical study on the conceptual model of flow and mass transport through fractured soft sedimentary rocks. Non-sorbing tracer experiments using naturally fractured cores and rock block specimens were carried out. Pottasium iodide was used as a tracer. The obtained breakthrough curves were interpreted and fitted by using a numerical simulator, and mass transport parameters, such as longitudinal dispersivity, matrix diffusion coefficient, transport aperture, were obtained. Mass transport simulations using a fracture network model, a continuum model and a double porosity model were performed to study the applicability of continuum model and double porosity model for transport in fractured sedimentary rock. (author)

  17. Cable Connected Spinning Spacecraft, 1. the Canonical Equations, 2. Urban Mass Transportation, 3

    Science.gov (United States)

    Sitchin, A.

    1972-01-01

    Work on the dynamics of cable-connected spinning spacecraft was completed by formulating the equations of motion by both the canonical equations and Lagrange's equations and programming them for numerical solution on a digital computer. These energy-based formulations will permit future addition of the effect of cable mass. Comparative runs indicate that the canonical formulation requires less computer time. Available literature on urban mass transportation was surveyed. Areas of the private rapid transit concept of urban transportation are also studied.

  18. Mass transport modelling for the electroreduction of CO2 on Cu nanowires

    Science.gov (United States)

    Raciti, David; Mao, Mark; Wang, Chao

    2018-01-01

    Mass transport plays an important role in CO2 reduction electrocatalysis. Albeit being more pronounced on nanostructured electrodes, the studies of mass transport for CO2 reduction have yet been limited to planar electrodes. We report here the development of a mass transport model for the electroreduction of CO2 on Cu nanowire electrodes. Fed with the experimental data from electrocatalytic studies, the local concentrations of CO2, {{{{HCO}}}3}-,{{{{CO}}}3}2- and OH- on the nanostructured electrodes are calculated by solving the diffusion equations with spatially distributed electrochemical reaction terms incorporated. The mass transport effects on the catalytic activity and selectivity of the Cu nanowire electrocatalysts are thus discussed by using the local pH as the descriptor. The established correlations between the electrocatalytic performance and the local pH shows that, the latter does not only determine the acid-base reaction equilibrium, but also regulates the mass transport and reaction kinetics. Based on these findings, the optimal range of local pH for CO2 reduction is discussed in terms of a fine balance among the suppression of hydrogen evolution, improvement of C2 product selectivity and limitation of CO2 supply. Our work highlights the importance of understanding the mass transport effects in interpretation of CO2 reduction electrocatalysis on high-surface-area catalysts.

  19. A correction technique for the dispersive effects of mass lumping for transport problems

    KAUST Repository

    Guermond, Jean-Luc; Pasquetti, Richard

    2013-01-01

    This paper addresses the well-known dispersion effect that mass lumping induces when solving transport-like equations. A simple anti-dispersion technique based on the lumped mass matrix is proposed. The method does not require any non-trivial matrix

  20. Fluid and mass transport in a single lymphatic blood vessel

    International Nuclear Information System (INIS)

    Bestman, A.R.

    1987-08-01

    The problem considers the single blood vessel model in pulmonary circulation in the presence of gravitation and mass transfer. The tissue surrounding the blood vessel is modelled as a permeable medium distinct from the blood vessel which is a normal free space. On the assumption that the mass concentration varies slowly at the interface between the blood vessel and the tissue, the problem is tackled by asymptotic approximation. A crucial point of the analysis is the dependence of the flow variables on the permeability K of the tissue in a completely arbitrary manner. A primary conjecture of the study is the intimacy of the pathological pulmonary edema and the parameter K. (author). 4 refs

  1. SITE-94. CAMEO: A model of mass-transport limited general corrosion of copper canisters

    International Nuclear Information System (INIS)

    Worgan, K.J.; Apted, M.J.

    1996-12-01

    This report describes the technical basis for the CAMEO code, which models the general, uniform corrosion of a copper canister either by transport of corrodants to the canister, or by transport of corrosion products away from the canister. According to the current Swedish concept for final disposal of spent nuclear fuels, extremely long containment times are achieved by thick (60-100 mm) copper canisters. Each canister is surrounded by a compacted bentonite buffer, located in a saturated, crystalline rock at a depth of around 500 m below ground level. Three diffusive transport-limited cases are identified for general, uniform corrosion of copper: General corrosion rate-limited by diffusive mass-transport of sulphide to the canister surface under reducing conditions; General corrosion rate-limited by diffusive mass-transport of oxygen to the canister surface under mildly oxidizing conditions; General corrosion rate-limited by diffusive mass-transport of copper chloride away from the canister surface under highly oxidizing conditions. The CAMEO code includes general corrosion models for each of the above three processes. CAMEO is based on the well-tested CALIBRE code previously developed as a finite-difference, mass-transfer analysis code for the SKI to evaluate long-term radionuclide release and transport in the near-field. A series of scoping calculations for the general, uniform corrosion of a reference copper canister are presented

  2. Activity-Based Costing Application in an Urban Mass Transport Company

    Directory of Open Access Journals (Sweden)

    Popesko Boris

    2011-12-01

    Full Text Available The purpose of this paper is to provide a basic overview of the application of Activity-Based Costing in an urban mass transport company which operates land public transport via buses and trolleys within the city. The case study was conducted using the Activity-Based Methodology in order to calculate the true cost of individual operations and to measure the profitability of particular transport lines. The case study analysis showed the possible effects of the application of the Activity-Based Costing for an urban mass transport company as well as the limitations of using the ABC methodology in the service industry. With regards to the application of the ABC methodology, the primary limitation of the accuracy of the conclusions is the quality of the non-financial information which had to be gathered throughout the implementation process. A basic limitation of the accurate data acquisition is the nature of the fare system of the transport company which does not allow the identification of the route that is taken by an individual passenger. The study illustrates the technique of ABC in urban mass transport and provides a real company example of information outputs of the ABC system. The users indicated that, the ABC model is very useful for profitability reporting and profit management. Also, the paper shows specific application of the Activity-Based Methodology in conditions of urban mass transport companies with regional specifics.

  3. Cellular automaton model of mass transport with chemical reactions

    International Nuclear Information System (INIS)

    Karapiperis, T.; Blankleider, B.

    1993-10-01

    The transport and chemical reactions of solutes are modelled as a cellular automaton in which molecules of different species perform a random walk on a regular lattice and react according to a local probabilistic rule. The model describes advection and diffusion in a simple way, and as no restriction is placed on the number of particles at a lattice site, it is also able to describe a wide variety of chemical reactions. Assuming molecular chaos and a smooth density function, we obtain the standard reaction-transport equations in the continuum limit. Simulations on one-and two-dimensional lattices show that the discrete model can be used to approximate the solutions of the continuum equations. We discuss discrepancies which arise from correlations between molecules and how these discrepancies disappear as the continuum limit is approached. Of particular interest are simulations displaying long-time behaviour which depends on long-wavelength statistical fluctuations not accounted for by the standard equations. The model is applied to the reactions a + b ↔ c and a + b → c with homogeneous and inhomogeneous initial conditions as well as to systems subject to autocatalytic reactions and displaying spontaneous formation of spatial concentration patterns. (author) 9 figs., 34 refs

  4. Comparison of crude oil interfacial behavior

    Energy Technology Data Exchange (ETDEWEB)

    Beetge, J.H.; Panchev, N. [Champion Technologies Inc., Fresno, TX (United States)

    2008-07-01

    The bulk properties of crude oil are used to predict its behaviour with regards to treatment, transport and processing. Surface active components, such as asphaltenes, are often used to study or explain critical interfacial behaviour of crude oil. This study investigated the differences and similarities in the interfacial behaviour of the collective surface active component in various crude oils from different sources. The properties of interfaces between crude oil and water were compared using a Teclis drop shape tensiometer. A portion of a crude oil sample was diluted in toluene and contacted with water in a rising drop configuration. Dynamic surface tension and interfacial rheology was examined as a function of time from the early stages of interface formation. Sinusoidal oscillation of the drop volume allowed for the evaluation of visco-elastic behaviour of the crude oil/water interface as it developed with time. The Gibbs elastic modulus, as well as its elastic and viscose components were calculated from the drop shape. The interfacial behaviour was expressed in terms of concentration, oscillation frequency and interface age. It was concluded that knowledge of crude oil interfacial character could be of value in the treatment, transport and processing of crude oils because the its behaviour may play a significant role in crude oil production and processing.

  5. Nine years of mass transport data in the eastern boundary of the North Atlantic Subtropical Gyre

    Science.gov (United States)

    Fraile-Nuez, Eugenio; MachíN, Francisco; VéLez-Belchí, Pedro; López-Laatzen, Federico; Borges, Rafael; BeníTez-Barrios, Verónica; HernáNdez-Guerra, Alonso

    2010-09-01

    One of the longest current meter time series in the Lanzarote Passage in the eastern boundary of the North Atlantic Subtropical Gyre has been used to determine and quantify the 9-year mean transport, the inter-annual and seasonal mass transport variability for the three water masses present in the area. Results show North Atlantic Central Water (NACW) flowing southward in the upper levels with a mean mass transport of -0.81 ± 1.48 Sv, Antarctic Intermediate Water (AAIW) flowing northward at intermediate levels with a mean transport of +0.09 ± 0.57 Sv and Mediterranean Water (MW) flowing southward in the deep part of the passage with a mean transport of -0.05 ± 0.17 Sv. Harmonic and wavelet analysis show the presence of a seasonal pattern in the passage for the three water masses. A maximum southward transport in winter and spring has been observed for the NACW followed by a minimum in summer and fall. Near zero values during winter and spring are found for AAIW, with a maximum northward value in summer and a negative value in fall, when this water mass reverses its flow. MW has a similar seasonal pattern to NACW. The vertical structure in the Lanzarote Passage can be approximated by four significant oscillatory modes which cumulatively explain 86.4% of the variance. The strong transport fluctuation found at the seasonal and inter-annual timescales demonstrates that the Eastern Boundary Current transport has a strong impact on meridional overturning estimates, thus indicating that to understand Meridional Overturning Circulation variability, these transport estimates at the eastern Atlantic margin are necessary.

  6. Stochastic modeling of mass transport in porous media

    International Nuclear Information System (INIS)

    Lim, Seung Cheol; Lee, Kun Jai

    1990-01-01

    The stochastic moments analysis technique is developed to investigate radionuclide migration in geologic porous media. The mechanisms for radionuclide transport are assumed to be advection in the micropore, radioactive decay of the species, and sorption on the pore wall. Two covariance functions of groundwater velocity, retardation factor, and concentration are derived to incorporate the geologic parameter uncertainty in porous media of small medium dispersivity. The parametric studies show that the correlation length of groundwater velocity has significant influence on the migration behavior of radionuclide. Macro dispersivity is dominantly affected by the fluctuation of groundwater velocity, while the fluctuation of retardation factor has a considerable effect on the retarded stochastic velocity. The upper estimated concentration evaluated from this stochastic moments analysis can be used as a practical conservative value for the performance assessment of nuclear waste repository

  7. Model of interfacial melting

    DEFF Research Database (Denmark)

    Mouritsen, Ole G.; Zuckermann, Martin J.

    1987-01-01

    A two-dimensional model is proposed to describe systems with phase transitions which take place in terms of crystalline as well as internal degrees of freedom. Computer simulation of the model shows that the interplay between the two sets of degrees of freedom permits observation of grain-boundar......-boundary formation and interfacial melting, a nonequilibrium process by which the system melts at the boundaries of a polycrystalline domain structure. Lipid membranes are candidates for systems with pronounced interfacial melting behavior....

  8. Directional mass transport in an atmospheric pressure surface barrier discharge.

    Science.gov (United States)

    Dickenson, A; Morabit, Y; Hasan, M I; Walsh, J L

    2017-10-25

    In an atmospheric pressure surface barrier discharge the inherent physical separation between the plasma generation region and downstream point of application reduces the flux of reactive chemical species reaching the sample, potentially limiting application efficacy. This contribution explores the impact of manipulating the phase angle of the applied voltage to exert a level of control over the electrohydrodynamic forces generated by the plasma. As these forces produce a convective flow which is the primary mechanism of species transport, the technique facilitates the targeted delivery of reactive species to a downstream point without compromising the underpinning species generation mechanisms. Particle Imaging Velocimetry measurements are used to demonstrate that a phase shift between sinusoidal voltages applied to adjacent electrodes in a surface barrier discharge results in a significant deviation in the direction of the plasma induced gas flow. Using a two-dimensional numerical air plasma model, it is shown that the phase shift impacts the spatial distribution of the deposited charge on the dielectric surface between the adjacent electrodes. The modified surface charge distribution reduces the propagation length of the discharge ignited on the lagging electrode, causing an imbalance in the generated forces and consequently a variation in the direction of the resulting gas flow.

  9. Modification of the finite element heat and mass transfer code (FEHMN) to model multicomponent reactive transport

    International Nuclear Information System (INIS)

    Viswanathan, H.S.

    1995-01-01

    The finite element code FEHMN is a three-dimensional finite element heat and mass transport simulator that can handle complex stratigraphy and nonlinear processes such as vadose zone flow, heat flow and solute transport. Scientists at LANL have been developed hydrologic flow and transport models of the Yucca Mountain site using FEHMN. Previous FEHMN simulations have used an equivalent K d model to model solute transport. In this thesis, FEHMN is modified making it possible to simulate the transport of a species with a rigorous chemical model. Including the rigorous chemical equations into FEHMN simulations should provide for more representative transport models for highly reactive chemical species. A fully kinetic formulation is chosen for the FEHMN reactive transport model. Several methods are available to computationally implement a fully kinetic formulation. Different numerical algorithms are investigated in order to optimize computational efficiency and memory requirements of the reactive transport model. The best algorithm of those investigated is then incorporated into FEHMN. The algorithm chosen requires for the user to place strongly coupled species into groups which are then solved for simultaneously using FEHMN. The complete reactive transport model is verified over a wide variety of problems and is shown to be working properly. The simulations demonstrate that gas flow and carbonate chemistry can significantly affect 14 C transport at Yucca Mountain. The simulations also provide that the new capabilities of FEHMN can be used to refine and buttress already existing Yucca Mountain radionuclide transport studies

  10. Temporal variability of mass transport across Canary Islands Channels

    Science.gov (United States)

    Marrero-Díaz, Ángeles; Rodríguez-Santana, Ángel; José Machín, Francisco; García-Weil, Luis; Sangrà, Pablo; Vélez-Belchí, Pedro; Fraile-Nuez, Eugenio

    2014-05-01

    The equatorward flowing Canary Current (CC) is the main feature of the circulation in the Canary Islands region. The CC flow perturbation by the Canary Islands originate the Canary Eddy Corridor which is the major pathway for long lived eddies in the subtropical North Atlantic (Sangrà et al., 2009, DSR). Therefore the variability of the CC passing through the Canary Archipelago will have both local and regional importance. Past studies on the CC variability trough the Canary Islands point out a clearly seasonal variability (Fraile-Nuez et al, 2010 (JGR); Hernández-Guerra et al, 2002 (DSR)). However those studies where focused on the eastern islands channels missing the variability through the western island channels which are the main source of long lived eddies. In order to fill this gap from November 2012 until September 2013 we conducted trimonthly surveys crossing the whole islands channels using opportunity ships (Naviera Armas Ferries). XBT and XCTD where launched along the cross channels transects. Additionally a closed box circling the Archipelago was performed on October 2013 as part of the cruise RAPROCAN-2013 (IEO) using also XBT and XCTD. Dynamical variables where derived inferring salinity from S(T,p) analytical relationships for the region updated with new XCTD data. High resolution, vertical sections of temperature, potential density, geostrophic velocity and transport where obtained. Our preliminary results suggest that the CC suffer a noticeable acceleration in those islands channels where eddy shedding is more frequent. They also indicate a clearly seasonal variability of the flows passing the islands channels. With this regard we observed significant differences on the obtained seasonal variability with respect the cited past studies on the eastern islands channel (Lanzarote / Fuerteventura - Africa coast). This work was co-funded by Canary Government (TRAMIC project: PROID20100092) and the European Union (FEDER).

  11. On the use of mass-conserving wind fields in chemistry-transport models

    Directory of Open Access Journals (Sweden)

    B. Bregman

    2003-01-01

    Full Text Available A new method has been developed that provides mass-conserving wind fields for global chemistry-transport models. In previous global Eulerian modeling studies a mass-imbalance was found between the model mass transport and the surface pressure tendencies. Several methods have been suggested to correct for this imbalance, but so far no satisfactory solution has been found. Our new method solves these problems by using the wind fields in a spherical harmonical form (divergence and vorticity by mimicing the physics of the weather forecast model as closely as possible. A 3-D chemistry-transport model was used to show that the calculated ozone fields with the new processing method agree remarkably better with ozone observations in the upper troposphere and lower stratosphere. In addition, the calculated age of air in the lower stratosphere show better agreement with observations, although the air remains still too young in the extra-tropical stratosphere.

  12. Mass Transport Modeling for The Electroreduction of CO2 on Cu Nanowires.

    Science.gov (United States)

    Raciti, David; Mao, Mark; Wang, Chao

    2017-11-20

    Mass transport plays an important role in the CO2 reduction electrocatalysis. Albeit being more pronounced on nanostructured electrodes, the studies of mass transport for CO2 reduction have yet been limited to planar electrodes. We report here the development of a mass transport model for the electroreduction of CO2 on Cu nanowire electrodes. Fed with the experimental data from electrocatalytic studies, the local concentrations of CO2, HCO3-, CO32- and OH- on the nanostructured electrodes are calculated by solving the diffusion equations with spatially distributed electrochemical reaction terms incorporated. The mass transport effects on the catalytic activity and selectivity of the Cu nanowire electrocatalysts are thus discussed by using the local pH as the descriptor. The established correlations between the electrocatalytic performance and the local pH shows that, the latter does not only determine the acid-base reaction equilibrium, but also regulates the mass transport and reaction kinetics. Based on these findings, the optimal range of local pH for the CO2 reduction is discussed in terms of a fine balance of the suppression of hydrogen evolution, improvement of C2 product selectivity and limitation of CO2 supply. Our work highlights the importance of understanding the mass transport effects in interpretation of the CO2 reduction electrocatalysis on high-surface-area catalysts. © 2017 IOP Publishing Ltd.

  13. A measurement of hydrogen transport in deuterium discharges using the dynamic response of the effective mass

    International Nuclear Information System (INIS)

    Dudok de Wit, T.; Duval, B.P.; Joye, B.; Lister, J.B.

    1992-02-01

    Particle tagging in a tokamak provides an attractive method for studying transport mechanisms. The injection of test particles at the plasma edge and the subsequent measurement of the evolution of their concentration at the centre can be used to quantify the underlying transport mechanisms. This has been carried out on the TCA tokamak by injecting hydrogen into a deuterium discharge, and simultaneously measuring the temporal evolution of the effective mass and the edge ionisation rate. (author) 3 figs., 9 refs

  14. Simplified semi-analytical model for mass transport simulation in unsaturated zone

    International Nuclear Information System (INIS)

    Sa, Bernadete L. Vieira de; Hiromoto, Goro

    2001-01-01

    This paper describes a simple model to determine the flux of radionuclides released from a concrete vault repository and its implementation through the development of a computer program. The radionuclide leach rate from waste is calculated using a model based on simple first order kinetics and the transport through porous media bellow the waste is determined using a semi-analytical solution of the mass transport equation. Results obtained in the IAEA intercomparison program are also related in this communication. (author)

  15. A model to quantify the resilience of mass railway transportation systems

    International Nuclear Information System (INIS)

    Adjetey-Bahun, Kpotissan; Birregah, Babiga; Châtelet, Eric; Planchet, Jean-Luc

    2016-01-01

    Traditional risk management approaches focus on perturbation events' likelihood and their consequences. However, recent events show that not all perturbation events can be foreseen. The concept of resilience has been introduced to measure not only the system's ability to absorb perturbations, but also its ability to rapidly recover from perturbations. In this work, we propose a simulation-based model for quantifying resilience in mass railway transportation systems by quantifying passenger delay and passenger load as the system's performance indicators. We integrate all subsystems that make up mass railway transportation systems (transportation, power, telecommunication and organisation subsystems) and their interdependencies. The model is applied to the Paris mass railway transportation system. The model's results show that since trains continue running within the system even by decreasing their speed, the system remains resilient. During the normal operation of the system as well as during perturbation, the model shows similarities with reality. The perturbation management plan that consists of setting up temporary train services on part of the impacted line while repairing the failed system's component is considered in this work. We also assess the extent to which some resilient system's capacities (i.e. absorption, adaptation and recovery) can increase the resilience of the system. - Highlights: • The need of resilience quantification models in sociotechnical systems. • We propose a simulation-based model. • This model is applied to Paris mass railway transportation system.

  16. MASS TRANSPORT AND TURBULENCE IN GRAVITATIONALLY UNSTABLE DISK GALAXIES. II. THE EFFECTS OF STAR FORMATION FEEDBACK

    Energy Technology Data Exchange (ETDEWEB)

    Goldbaum, Nathan J. [National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, 1205 W. Clark St., Urbana, IL 61801 (United States); Krumholz, Mark R. [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2601 (Australia); Forbes, John C., E-mail: ngoldbau@illinois.edu [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

    2016-08-10

    Self-gravity and stellar feedback are capable of driving turbulence and transporting mass and angular momentum in disk galaxies, but the balance between them is not well understood. In the previous paper in this series, we showed that gravity alone can drive turbulence in galactic disks, regulate their Toomre Q parameters to ∼1, and transport mass inwards at a rate sufficient to fuel star formation in the centers of present-day galaxies. In this paper we extend our models to include the effects of star formation feedback. We show that feedback suppresses galaxies’ star formation rates by a factor of ∼5 and leads to the formation of a multi-phase atomic and molecular interstellar medium. Both the star formation rate and the phase balance produced in our simulations agree well with observations of nearby spirals. After our galaxies reach steady state, we find that the inclusion of feedback actually lowers the gas velocity dispersion slightly compared to the case of pure self-gravity, and also slightly reduces the rate of inward mass transport. Nevertheless, we find that, even with feedback included, our galactic disks self-regulate to Q ∼ 1, and transport mass inwards at a rate sufficient to supply a substantial fraction of the inner disk star formation. We argue that gravitational instability is therefore likely to be the dominant source of turbulence and transport in galactic disks, and that it is responsible for fueling star formation in the inner parts of galactic disks over cosmological times.

  17. Thermo-fluidic devices and materials inspired from mass and energy transport phenomena in biological system

    Institute of Scientific and Technical Information of China (English)

    Jian XIAO; Jing LIU

    2009-01-01

    Mass and energy transport consists of one of the most significant physiological processes in nature, which guarantees many amazing biological phenomena and activ-ities. Borrowing such idea, many state-of-the-art thermo-fluidic devices and materials such as artificial kidneys, carrier erythrocyte, blood substitutes and so on have been successfully invented. Besides, new emerging technologies are still being developed. This paper is dedicated to present-ing a relatively complete review of the typical devices and materials in clinical use inspired by biological mass and energy transport mechanisms. Particularly, these artificial thermo-fluidic devices and materials will be categorized into organ transplantation, drug delivery, nutrient transport, micro operation, and power supply. Potential approaches for innovating conventional technologies were discussed, corresponding biological phenomena and physical mechan-isms were interpreted, future promising mass-and-energy-transport-based bionic devices were suggested, and prospects along this direction were pointed out. It is expected that many artificial devices based on biological mass and energy transport principle will appear to better improve vari-ous fields related to human life in the near future.

  18. Required momentum, heat, and mass transport experiments for liquid-metal blankets

    International Nuclear Information System (INIS)

    Tillack, M.S.; Sze, D.K.; Abdou, M.A.

    1986-01-01

    Through the effects on fluid flow, many aspects of blanket behavior are affected by magnetohydrodynamic (MHD) effects, including pressure drop, heat transfer, mass transfer, and structural behavior. In this paper, a set of experiments is examined that could be performed in order to reduce the uncertainties in the highly related set of issues dealing with momentum, heat, and mass transport under the influence of a strong magnetic field (i.e., magnetic transport phenomena). By improving our basic understanding and by providing direct experimental data on blanket behavior, these experiments will lead to improved designs and an accurate assessment of the attractiveness of liquid-metal blankets

  19. Amplified CPEs enhancement of chorioamnion membrane mass transport by encapsulation in nano-sized PLGA particles.

    Science.gov (United States)

    Azagury, Aharon; Amar-Lewis, Eliz; Appel, Reut; Hallak, Mordechai; Kost, Joseph

    2017-08-01

    Chemical penetration enhancers (CPEs) have long been used for mass transport enhancement across membranes. Many CPEs are used in a solution or gel and could be a solvent. The use of CPEs is mainly limited due to their toxicity/irritation levels. This study presents the evaluation of encapsulated CPEs in nano-sized polymeric particles on the chorioamnion (CA) membrane mass transport. CPEs' mass encapsulated in nanoparticles was decreased by 10,000-fold. Interestingly, this approach resulted in a 6-fold increase in mass transport across the CA. This approach may also be used with other CPEs' base applications necessitating lower CPE concentration. Applying Ultrasound (US) has shown to increase the release rate of and also the mass transport across the CA membrane. It is proposed that encapsulated CPEs penetrate into the CA membrane thus prolonging their exposure, possibly extending their penetration into the CA membrane, while insonation also deepens their penetration into the CA membrane. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Momentum, heat, and mass transfer analogy for vertical hydraulic transport of inert particles

    Directory of Open Access Journals (Sweden)

    Jaćimovski Darko R.

    2014-01-01

    Full Text Available Wall-to-bed momentum, heat and mass transfer in vertical liquid-solids flow, as well as in single phase flow, were studied. The aim of this investigation was to establish the analogy among those phenomena. Also, effect of particles concentration on momentum, heat and mass transfer was studied. The experiments in hydraulic transport were performed in a 25.4 mm I.D. cooper tube equipped with a steam jacket, using spherical glass particles of 1.94 mm in diameter and water as a transport fluid. The segment of the transport tube used for mass transfer measurements was inside coated with benzoic acid. In the hydraulic transport two characteristic flow regimes were observed: turbulent and parallel particle flow regime. The transition between two characteristic regimes (γ*=0, occurs at a critical voidage ε≈0.85. The vertical two-phase flow was considered as the pseudofluid, and modified mixture-wall friction coefficient (fw and modified mixture Reynolds number (Rem were introduced for explanation of this system. Experimental data show that the wall-to-bed momentum, heat and mass transfer coefficients, in vertical flow of pseudofluid, for the turbulent regime are significantly higher than in parallel regime. Wall-to-bed, mass and heat transfer coefficients in hydraulic transport of particles were much higher then in single-phase flow for lower Reynolds numbers (Re15000, there was not significant difference. The experimental data for wall-to-bed momentum, heat and mass transfer in vertical flow of pseudofluid in parallel particle flow regime, show existing analogy among these three phenomena. [Projekat Ministarstva nauke Republike Srbije, br. 172022

  1. A High-Resolution Model of Water Mass Transformation and Transport in the Weddell Sea

    Science.gov (United States)

    Hazel, J.; Stewart, A.

    2016-12-01

    The ocean circulation around the Antarctic margins has a pronounced impact on the global ocean and climate system. One of these impacts includes closing the global meridional overturning circulation (MOC) via formation of dense Antarctic Bottom Water (AABW), which ventilates a large fraction of the subsurface ocean. AABW is also partially composed of modified Circumpolar Deep Water (CDW), a warm, mid-depth water mass whose transport towards the continent has the potential to induce rapid retreat of marine-terminating glaciers. Previous studies suggest that these water mass exchanges may be strongly influenced by high-frequency processes such as downslope gravity currents, tidal flows, and mesoscale/submesoscale eddy transport. However, evaluating the relative contributions of these processes to near-Antarctic water mass transports is hindered by the region's relatively small scales of motion and the logistical difficulties in taking measurements beneath sea ice.In this study we develop a regional model of the Weddell Sea, the largest established source of AABW. The model is forced by an annually-repeating atmospheric state constructed from the Antarctic Mesoscale Prediction System data and by annually-repeating lateral boundary conditions constructed from the Southern Ocean State Estimate. The model incorporates the full Filchner-Ronne cavity and simulates the thermodynamics and dynamics of sea ice. To analyze the role of high-frequency processes in the transport and transformation of water masses, we compute the model's overturning circulation, water mass transformations, and ice sheet basal melt at model horizontal grid resolutions ranging from 1/2 degree to 1/24 degree. We temporally decompose the high-resolution (1/24 degree) model circulation into components due to mean, eddy and tidal flows and discuss the geographical dependence of these processes and their impact on water mass transformation and transport.

  2. A correction technique for the dispersive effects of mass lumping for transport problems

    KAUST Repository

    Guermond, Jean-Luc

    2013-01-01

    This paper addresses the well-known dispersion effect that mass lumping induces when solving transport-like equations. A simple anti-dispersion technique based on the lumped mass matrix is proposed. The method does not require any non-trivial matrix inversion and has the same anti-dispersive effects as the consistent mass matrix. A novel quasi-lumping technique for P2 finite elements is introduced. Higher-order extensions of the method are also discussed. © 2012 Elsevier B.V.

  3. Modification of the finite element heat and mass transfer code (FEHM) to model multicomponent reactive transport

    International Nuclear Information System (INIS)

    Viswanathan, H.S.

    1996-08-01

    The finite element code FEHMN, developed by scientists at Los Alamos National Laboratory (LANL), is a three-dimensional finite element heat and mass transport simulator that can handle complex stratigraphy and nonlinear processes such as vadose zone flow, heat flow and solute transport. Scientists at LANL have been developing hydrologic flow and transport models of the Yucca Mountain site using FEHMN. Previous FEHMN simulations have used an equivalent Kd model to model solute transport. In this thesis, FEHMN is modified making it possible to simulate the transport of a species with a rigorous chemical model. Including the rigorous chemical equations into FEHMN simulations should provide for more representative transport models for highly reactive chemical species. A fully kinetic formulation is chosen for the FEHMN reactive transport model. Several methods are available to computationally implement a fully kinetic formulation. Different numerical algorithms are investigated in order to optimize computational efficiency and memory requirements of the reactive transport model. The best algorithm of those investigated is then incorporated into FEHMN. The algorithm chosen requires for the user to place strongly coupled species into groups which are then solved for simultaneously using FEHMN. The complete reactive transport model is verified over a wide variety of problems and is shown to be working properly. The new chemical capabilities of FEHMN are illustrated by using Los Alamos National Laboratory's site scale model of Yucca Mountain to model two-dimensional, vadose zone 14 C transport. The simulations demonstrate that gas flow and carbonate chemistry can significantly affect 14 C transport at Yucca Mountain. The simulations also prove that the new capabilities of FEHMN can be used to refine and buttress already existing Yucca Mountain radionuclide transport studies

  4. Global vertical mass transport by clouds - A two-dimensional model study

    International Nuclear Information System (INIS)

    Olofsson, Mats

    1988-05-01

    A two-dimensional global dispersion model, where vertical transport in the troposphere carried out by convective as well as by frontal cloud systems is explicitly treated, is developed from an existing diffusion model. A parameterization scheme for the cloud transport, based on global cloud statistics, is presented. The model has been tested by using Kr-85, Rn-222 and SO 2 as tracers. Comparisons have been made with observed distributions of these tracers, but also with model results without the cloud transport, using eddy diffusion as the primary means of vertical transport. The model results indicate that for trace species with a turnover time of days to weeks, the introduction of cloud-transport gives much more realistic simulations of their vertical distribution. Layers of increased mixing ratio with height, which can be found in real atmosphere, are reproduced in our cloud-transport model profiles, but can never be simulated with a pure eddy diffusion model. The horizontal transport in the model, by advection and eddy diffusion, gives a realistic distribution between the hemispheres of the more long-lived tracers (Kr-85). A combination of vertical transport by convective and frontal cloud systems is shown to improve the model simulations, compared to limiting it to convective transport only. The importance of including cumulus clouds in the convective transport scheme, in addition to the efficient transport by cumulonimbus clouds, is discussed. The model results are shown to be more sensitive to the vertical detrainment distribution profile than to the absolute magnitude of the vertical mass transport. The scavenging processes for SO 2 are parameterized without the introduction of detailed chemistry. An enhanced removal, due to the increased contact with droplets in the in-cloud lifting process, is introduced in the model. (author)

  5. An assessment of transportation issues under exceptional conditions : the case of the mass media and the Northridge Earthquake

    Science.gov (United States)

    1998-05-01

    This study explores how the mass media covered transportation issues following the 1994 Northridge earthquake. The mass media were a vital channel for travel information, and they provided considerable information to the public about the safety of tr...

  6. Influence of Capillary Condensation Effects on Mass Transport through Porous Membranes

    Czech Academy of Sciences Publication Activity Database

    Uchytil, Petr; Petričkovič, Roman; Thomas, S.; Siedel-Morgenstern, A.

    2003-01-01

    Roč. 33, č. 3 (2003), s. 273-281 ISSN 1383-5866 R&D Projects: GA ČR GA104/01/0945 Institutional research plan: CEZ:AV0Z4072921 Keywords : capillary condensation * mass transport * gas separation Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.355, year: 2003

  7. No association between striatal dopamine transporter binding and body mass index

    DEFF Research Database (Denmark)

    van de Giessen, Elsmarieke; Hesse, Swen; Caan, Matthan W A

    2013-01-01

    Dopamine is one among several neurotransmitters that regulate food intake and overeating. Thus, it has been linked to the pathophysiology of obesity and high body mass index (BMI). Striatal dopamine D(2) receptor availability is lower in obesity and there are indications that striatal dopamine...... transporter (DAT) availability is also decreased. In this study, we tested whether BMI and striatal DAT availability are associated....

  8. Next-generation satellite gravimetry for measuring mass transport in the Earth system

    NARCIS (Netherlands)

    Teixeira Encarnação, J.

    2015-01-01

    The main objective of the thesis is to identify the optimal set-up for future satellite gravimetry missions aimed at monitoring mass transport in the Earth’s system.The recent variability of climatic patterns, the spread of arid regions and associ- ated changes in the hydrological cycle, and

  9. Mass transport mechanism in the collision of sulphur on medium-weight nuclei

    International Nuclear Information System (INIS)

    Lejeune, A.; Richert, J.

    1980-01-01

    The reactions of 32 S on 59 Co, 65 Cu, 74 Ge, 79 Br, 85 Rb, 89 Y are studied. An explanation for the specific shape of the double differential cross sections as a function of the scattering angle and the mass asymmetry is given in the framework of a transport model. Conclusions about the reaction mechanism are drawn

  10. Volumetric vs Mass Velocity in Analyzing Convective-Diffusive Transport Processes in Liquids

    Science.gov (United States)

    Brenner, Howard

    2000-11-01

    Because mass rather than volume is preserved in fluid-mechanical problems involving density changes, a natural predilection exists for quantifying convective-diffusive transport phenomena in terms of a velocity field based upon mass, rather than volume. Indeed, in the classic BSL "Transport Phenomena" textbook, but a single reference exists even to the very concept of a volume velocity, and even then it is relegated to a homework assignment. However, especially when dealing with transport in fluids in which the mass density of the conserved property being transported (e.g., chemical species, internal energy, etc.) is independent of the prevailing pressure, as is largely true in the case of liquids, overwhelming advantages exist is preferring the volume velocity over the more ubiquitous and classical mass velocity. In a generalization of ideas pioneered by D. D. Joseph and co-workers, we outline the reasons for this volumetric velocity preference in a broad general context by identifying a large class of physical problems whose solutions are rendered more accessible by exploiting this unconventional velocity choice.

  11. Role of interfacial rheological properties in oil field chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Lakatos-Szabo, J.; Lakatos, I.; Kosztin, B.

    1996-12-31

    Interfacial rheological properties of different Hungarian crude oil/water systems were determined in wide temperature and shear rate range and in presence of inorganic electrolytes, tensides, alkaline materials and polymers. The detailed laboratory study definitely proved that the interfacial rheological properties are extremely sensitive parameters towards the chemical composition of inmiscible formation liquids. Comparison and interpretation of the interfacial rheological properties may contribute significantly to extension of the weaponry of the reservoir characterization, better understanding of the displacement mechanism, development of the more profitable EOR/IOR methods, intensification of the surface technologies, optimization of the pipeline transportation and improvement of the refinery operations. It was evidenced that the interfacial rheology is an efficient and powerful detection technique, which may enhance the knowledge on formation, structure, properties and behaviour of interfacial layers. 17 refs., 18 figs., 2 tabs.

  12. Mass flow and velocity profiles in Neurospora hyphae: partial plug flow dominates intra-hyphal transport.

    Science.gov (United States)

    Abadeh, Aryan; Lew, Roger R

    2013-11-01

    Movement of nuclei, mitochondria and vacuoles through hyphal trunks of Neurospora crassa were vector-mapped using fluorescent markers and green fluorescent protein tags. The vectorial movements of all three were strongly correlated, indicating the central role of mass (bulk) flow in cytoplasm movements in N. crassa. Profiles of velocity versus distance from the hyphal wall did not match the parabolic shape predicted by the ideal Hagen-Poiseuille model of flow at low Reynolds number. Instead, the profiles were flat, consistent with a model of partial plug flow due to the high concentration of organelles in the flowing cytosol. The intra-hyphal pressure gradients were manipulated by localized external osmotic treatments to demonstrate the dependence of velocity (and direction) on pressure gradients within the hyphae. The data support the concept that mass transport, driven by pressure gradients, dominates intra-hyphal transport. The transport occurs by partial plug flow due to the organelles in the cytosol.

  13. Non-contact, non-destructive, quantitative probing of interfacial trap sites for charge carrier transport at semiconductor-insulator boundary

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Wookjin; Miyakai, Tomoyo; Sakurai, Tsuneaki; Saeki, Akinori [Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita 565-0871 (Japan); Yokoyama, Masaaki [Kaneka Fundamental Technology Research Alliance Laboratories, Graduate School of Engineering, Osaka University, Suita 565-0871 (Japan); Seki, Shu, E-mail: seki@chem.eng.osaka-u.ac.jp [Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita 565-0871 (Japan); Kaneka Fundamental Technology Research Alliance Laboratories, Graduate School of Engineering, Osaka University, Suita 565-0871 (Japan)

    2014-07-21

    The density of traps at semiconductor–insulator interfaces was successfully estimated using microwave dielectric loss spectroscopy with model thin-film organic field-effect transistors. The non-contact, non-destructive analysis technique is referred to as field-induced time-resolved microwave conductivity (FI-TRMC) at interfaces. Kinetic traces of FI-TRMC transients clearly distinguished the mobile charge carriers at the interfaces from the immobile charges trapped at defects, allowing both the mobility of charge carriers and the number density of trap sites to be determined at the semiconductor-insulator interfaces. The number density of defects at the interface between evaporated pentacene on a poly(methylmethacrylate) insulating layer was determined to be 10{sup 12 }cm{sup −2}, and the hole mobility was up to 6.5 cm{sup 2} V{sup −1} s{sup −1} after filling the defects with trapped carriers. The FI-TRMC at interfaces technique has the potential to provide rapid screening for the assessment of interfacial electronic states in a variety of semiconductor devices.

  14. Modeling and measurement of interfacial area concentration in two-phase flow

    International Nuclear Information System (INIS)

    Paranjape, Sidharth; Ishii, Mamoru; Hibiki, Takashi

    2010-01-01

    This paper presents experimental and modeling approaches in characterizing interfacial structures in gas-liquid two-phase flow. For the modeling of the interfacial structure characterization, the interfacial area transport equation proposed earlier has been studied to provide a dynamic and mechanistic prediction tool for two-phase flow analysis. A state-of-the-art four-sensor conductivity probe technique has been developed to obtain detailed local interfacial structure information in a wide range of flow regimes spanning from bubbly to churn-turbulent flows. Newly obtained interfacial area data in 8 x 8 rod-bundle test section are also presented. This paper also reviews available models of the interfacial area sink and source terms and existing databases. The interfacial area transport equation has been benchmarked using condensation bubbly flow data.

  15. Mass transport in Ti0.5Sb2Te3 phase-change nanobridge

    International Nuclear Information System (INIS)

    Ji, Xinglong; Wu, Liangcai; Lv, Shilong; Rao, Feng; Zhu, Min; Song, Zhitang; Zhou, Xilin; Feng, Songlin

    2014-01-01

    Investigation of atomic migration behavior in nanoscale phase-change material is very valuable for phase-change memory applications. In this work, Ti 0.5 Sb 2 Te 3 -based phase-change nanobridges were fabricated and mass transport by atomic migration was studied. A 3-D finite-element simulation on the electrothermal field was introduced to describe the electrothermal environment in the phase-change region. During the nanosecond operation, an obvious compositional distribution resulting from atomic migration was observed in the Ti 0.5 Sb 2 Te 3 phase-change nanobridge. Based on the mass continuity equation, a physical model for mass transport is proposed to illustrate that the density variation during the amorphous-to-crystalline structural transformation is the main reason for the atomic migration in nanoscale Ti 0.5 Sb 2 Te 3 phase-change material

  16. Water mass distributions and transports for the 2014 GEOVIDE cruise in the North Atlantic

    Science.gov (United States)

    García-Ibáñez, Maribel I.; Pérez, Fiz F.; Lherminier, Pascale; Zunino, Patricia; Mercier, Herlé; Tréguer, Paul

    2018-04-01

    We present the distribution of water masses along the GEOTRACES-GA01 section during the GEOVIDE cruise, which crossed the subpolar North Atlantic Ocean and the Labrador Sea in the summer of 2014. The water mass structure resulting from an extended optimum multiparameter (eOMP) analysis provides the framework for interpreting the observed distributions of trace elements and their isotopes. Central Waters and Subpolar Mode Waters (SPMW) dominated the upper part of the GEOTRACES-GA01 section. At intermediate depths, the dominant water mass was Labrador Sea Water, while the deep parts of the section were filled by Iceland-Scotland Overflow Water (ISOW) and North-East Atlantic Deep Water. We also evaluate the water mass volume transports across the 2014 OVIDE line (Portugal to Greenland section) by combining the water mass fractions resulting from the eOMP analysis with the absolute geostrophic velocity field estimated through a box inverse model. This allowed us to assess the relative contribution of each water mass to the transport across the section. Finally, we discuss the changes in the distribution and transport of water masses between the 2014 OVIDE line and the 2002-2010 mean state. At the upper and intermediate water levels, colder end-members of the water masses replaced the warmer ones in 2014 with respect to 2002-2010, in agreement with the long-term cooling of the North Atlantic Subpolar Gyre that started in the mid-2000s. Below 2000 dbar, ISOW increased its contribution in 2014 with respect to 2002-2010, with the increase being consistent with other estimates of ISOW transports along 58-59° N. We also observed an increase in SPMW in the East Greenland Irminger Current in 2014 with respect to 2002-2010, which supports the recent deep convection events in the Irminger Sea. From the assessment of the relative water mass contribution to the Atlantic Meridional Overturning Circulation (AMOC) across the OVIDE line, we conclude that the larger AMOC intensity in

  17. Water mass distributions and transports for the 2014 GEOVIDE cruise in the North Atlantic

    Directory of Open Access Journals (Sweden)

    M. I. García-Ibáñez

    2018-04-01

    Full Text Available We present the distribution of water masses along the GEOTRACES-GA01 section during the GEOVIDE cruise, which crossed the subpolar North Atlantic Ocean and the Labrador Sea in the summer of 2014. The water mass structure resulting from an extended optimum multiparameter (eOMP analysis provides the framework for interpreting the observed distributions of trace elements and their isotopes. Central Waters and Subpolar Mode Waters (SPMW dominated the upper part of the GEOTRACES-GA01 section. At intermediate depths, the dominant water mass was Labrador Sea Water, while the deep parts of the section were filled by Iceland–Scotland Overflow Water (ISOW and North-East Atlantic Deep Water. We also evaluate the water mass volume transports across the 2014 OVIDE line (Portugal to Greenland section by combining the water mass fractions resulting from the eOMP analysis with the absolute geostrophic velocity field estimated through a box inverse model. This allowed us to assess the relative contribution of each water mass to the transport across the section. Finally, we discuss the changes in the distribution and transport of water masses between the 2014 OVIDE line and the 2002–2010 mean state. At the upper and intermediate water levels, colder end-members of the water masses replaced the warmer ones in 2014 with respect to 2002–2010, in agreement with the long-term cooling of the North Atlantic Subpolar Gyre that started in the mid-2000s. Below 2000 dbar, ISOW increased its contribution in 2014 with respect to 2002–2010, with the increase being consistent with other estimates of ISOW transports along 58–59° N. We also observed an increase in SPMW in the East Greenland Irminger Current in 2014 with respect to 2002–2010, which supports the recent deep convection events in the Irminger Sea. From the assessment of the relative water mass contribution to the Atlantic Meridional Overturning Circulation (AMOC across the OVIDE line, we conclude

  18. Electrocatalytic performance of fuel cell reactions at low catalyst loading and high mass transport.

    Science.gov (United States)

    Zalitis, Christopher M; Kramer, Denis; Kucernak, Anthony R

    2013-03-28

    An alternative approach to the rotating disk electrode (RDE) for characterising fuel cell electrocatalysts is presented. The approach combines high mass transport with a flat, uniform, and homogeneous catalyst deposition process, well suited for studying intrinsic catalyst properties at realistic operating conditions of a polymer electrolyte fuel cell (PEFC). Uniform catalyst layers were produced with loadings as low as 0.16 μgPt cm(-2) and thicknesses as low as 200 nm. Such ultra thin catalyst layers are considered advantageous to minimize internal resistances and mass transport limitations. Geometric current densities as high as 5.7 A cm(-2)Geo were experimentally achieved at a loading of 10.15 μgPt cm(-2) for the hydrogen oxidation reaction (HOR) at room temperature, which is three orders of magnitude higher than current densities achievable with the RDE. Modelling of the associated diffusion field suggests that such high performance is enabled by fast lateral diffusion within the electrode. The electrodes operate over a wide potential range with insignificant mass transport losses, allowing the study of the ORR at high overpotentials. Electrodes produced a specific current density of 31 ± 9 mA cm(-2)Spec at a potential of 0.65 V vs. RHE for the oxygen reduction reaction (ORR) and 600 ± 60 mA cm(-2)Spec for the peak potential of the HOR. The mass activity of a commercial 60 wt% Pt/C catalyst towards the ORR was found to exceed a range of literature PEFC mass activities across the entire potential range. The HOR also revealed fine structure in the limiting current range and an asymptotic current decay for potentials above 0.36 V. These characteristics are not visible with techniques limited by mass transport in aqueous media such as the RDE.

  19. Structural instability of atmospheric flows under perturbations of the mass balance and effect in transport calculations

    International Nuclear Information System (INIS)

    Núñez, M A; Mendoza, R

    2015-01-01

    Several methods to estimate the velocity field of atmospheric flows, have been proposed to the date for applications such as emergency response systems, transport calculations and for budget studies of all kinds. These applications require a wind field that satisfies the conservation of mass but, in general, estimated wind fields do not satisfy exactly the continuity equation. An approach to reduce the effect of using a divergent wind field as input in the transport-diffusion equations, was proposed in the literature. In this work, a linear local analysis of a wind field, is used to show analytically that the perturbation of a large-scale nondivergent flow can yield a divergent flow with a substantially different structure. The effects of these structural changes in transport calculations are illustrated by means of analytic solutions of the transport equation

  20. A Summary of Interfacial Heat Transfer Models and Correlations

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Sung Won; Cho, Hyung Kyu; Lee, Young Jin; Kim, Hee Chul; Jung, Young Jong; Kim, K. D. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2007-10-15

    A long term project has been launched in October 2006 to develop a plant safety analysis code. 5 organizations are joining together for the harmonious coworking to build up the code. In this project, KAERI takes the charge of the building up the physical models and correlations about the transport phenomena. The momentum and energy transfer terms as well as the mass are surveyed from the RELAP5/MOD3, RELAP5-3D, CATHARE, and TRAC-M does. Also the recent papers are surveyed. Among these resources, most of the CATHARE models are based on their own experiment and test results. Thus, the CATHARE models are only used as the comparison purposes. In this paper, a summary of the models and the correlations about the interfacial heat transfer are represented. These surveyed models and correlations will be tested numerically and one correlation is selected finally.

  1. Mass transport in fracture media: impact of the random function model assumed for fractures conductivity

    International Nuclear Information System (INIS)

    Capilla, J. E.; Rodrigo, J.; Gomez Hernandez, J. J.

    2003-01-01

    Characterizing the uncertainty of flow and mass transport models requires the definition of stochastic models to describe hydrodynamic parameters. Porosity and hydraulic conductivity (K) are two of these parameters that exhibit a high degree of spatial variability. K is usually the parameter whose variability influence to a more extended degree solutes movement. In fracture media, it is critical to properly characterize K in the most altered zones where flow and solutes migration tends to be concentrated. However, K measurements use to be scarce and sparse. This fact calls to consider stochastic models that allow quantifying the uncertainty of flow and mass transport predictions. This paper presents a convective transport problem solved in a 3D block of fractured crystalline rock. the case study is defined based on data from a real geological formation. As the scarcity of K data in fractures does not allow supporting classical multi Gaussian assumptions for K in fractures, the non multi Gaussian hypothesis has been explored, comparing mass transport results for alternative Gaussian and non-Gaussian assumptions. The latter hypothesis allows reproducing high spatial connectivity for extreme values of K. This feature is present in nature, might lead to reproduce faster solute pathways, and therefore should be modeled in order to obtain reasonably safe prediction of contaminants migration in a geological formation. The results obtained for the two alternative hypotheses show a remarkable impact of the K random function model in solutes movement. (Author) 9 refs

  2. Study on flow and mass transport through fractured sedimentary rocks (2)

    International Nuclear Information System (INIS)

    Shimo, Michito; Kumamoto, Sou; Karasaki, Kenzi; Sato, Hisashi; Sawada, Atsushi

    2009-03-01

    It is important for safety assessment of HLW geological disposal to understand hydro-geological conditions at the investigation area, and to evaluate groundwater flow and mass transport model and parameters, at each investigation phase. Traditionally, for Neogene sedimentary rock, the grain spacing of sediments has been considered as the dominant migration path. However, fractures of sedimentary rock could act as dominant paths, although they were soft sedimentary rocks. In this study, as part of developing groundwater flow and mass transport evaluation methodologies of such a fractured sedimentary rock' distributed area, we conducted two different scale of studies; 1) core rock sample scale and 2) several kilometer scale. For the core rock sample scale, some of laboratory hydraulic and tracer experiments have conducted using the rock cores with tailored parallel fracture, obtained at pilot borehole drilled in the vicinity of ventilation shaft. From the test results, hydraulic conductivity, diffusion coefficient, transport aperture, dispersion length and etc. was evaluated. Based on these test results, the influence of these parameters onto mass transport behavior of fractures sedimentary rocks was examined. For larger scale, such as several kilometer scale, the regional scale groundwater flow was examined using temperature data observed along the boreholes at Horonobe site. The results show that the low permeable zone between the boreholes might be estimated. (author)

  3. Mass transfer processes and field-scale transport of organic solutes

    International Nuclear Information System (INIS)

    Brusseau, M.L.

    1990-01-01

    The influence of mass transfer processes, such as sorption/desorption and mass transfer between immiscible liquids and water, on the transport of organic solutes is discussed. Rate-limited sorption of organic solutes caused by a diffusion-constrained mechanism is shown to be significant under laboratory conditions. The significance of the impact of nonequilibrium sorption on field-scale transport is scale dependent. The impact of organic liquids on mass transfer and transport of organic solutes depends upon the nature of the solute and the nature and form of the organic liquid. For example, while retardation of nonionic solutes is decreased in mixed-solvent systems, (i.e. systems comprised of water and a miscible organic liquid or an immiscible liquid present in concentrations below phase separation), the retardation of organic acids may, in some cases, increase with addition of a cosolvent. While the presence of an immiscible liquid existing as a mobile phase will reduce retention of organic solutes, the presence of residual saturation of an immiscible liquid can significantly increase retention. A model is presented that incorporates the effects of retention resulting from residual saturation, as well as nonequilibrium sorption, on the transport of organic solutes. (Author) (70 refs., 3 figs.)

  4. Multicomponent mass transport model: a model for simulating migration of radionuclides in ground water

    International Nuclear Information System (INIS)

    Washburn, J.F.; Kaszeta, F.E.; Simmons, C.S.; Cole, C.R.

    1980-07-01

    This report presents the results of the development of a one-dimensional radionuclide transport code, MMT2D (Multicomponent Mass Transport), for the AEGIS Program. Multicomponent Mass Transport is a numerical solution technique that uses the discrete-parcel-random-wald (DPRW) method to directly simulate the migration of radionuclides. MMT1D accounts for: convection;dispersion; sorption-desorption; first-order radioactive decay; and n-membered radioactive decay chains. Comparisons between MMT1D and an analytical solution for a similar problem show that: MMT1D agrees very closely with the analytical solution; MMT1D has no cumulative numerical dispersion like that associated with solution techniques such as finite differences and finite elements; for current AEGIS applications, relatively few parcels are required to produce adequate results; and the power of MMT1D is the flexibility of the code in being able to handle complex problems for which analytical solution cannot be obtained. Multicomponent Mass Transport (MMT1D) codes were developed at Pacific Northwest Laboratory to predict the movement of radiocontaminants in the saturated and unsaturated sediments of the Hanford Site. All MMT models require ground-water flow patterns that have been previously generated by a hydrologic model. This report documents the computer code and operating procedures of a third generation of the MMT series: the MMT differs from previous versions by simulating the mass transport processes in systems with radionuclide decay chains. Although MMT is a one-dimensional code, the user is referred to the documentation of the theoretical and numerical procedures of the three-dimensional MMT-DPRW code for discussion of expediency, verification, and error-sensitivity analysis

  5. The use of the dusty-gas model for the description of mass transport with chemical reaction in porous media

    NARCIS (Netherlands)

    Veldsink, J.W.; Veldsink, J.W.; van Damme, Rudolf M.J.; Versteeg, Geert; van Swaaij, Willibrordus Petrus Maria

    1995-01-01

    In the present study, mass transport accompanied by chemical reactions in porous media is studied according to the Fick model and the dusty-gas model. For mass transport accompanied by a chemical reaction in catalyst structures showing a plane, line, or point of symmetry, the approximate analytical

  6. Species Uptake and Mass Transport in Membranes for Vanadium Redox Flow Batteries

    International Nuclear Information System (INIS)

    Elgammal, Ramez A.; Tang, Zhijiang; Sun, Che-Nan; Lawton, Jamie; Zawodzinski, Thomas A.

    2017-01-01

    In this contribution, we provide a synthesis of results to date describing uptake and mass transport of water, vanadium species and protons in Nafion membranes for use as separators in VRFBs. Resistance issues as well as species cross-over are important contributors to performance loss in VRFBs. After a brief discussion of our state-of-the-art cell performance, we consider the uptake and transport of various species through a number of membrane materials. We draw together numerous previous studies and augment them with new data to provide a summary of our present state of understanding of the experimental facts regarding membrane behavior.

  7. Transient Mass and Thermal Transport during Methane Adsorption into the Metal-Organic Framework HKUST-1.

    Science.gov (United States)

    Babaei, Hasan; McGaughey, Alan J H; Wilmer, Christopher E

    2018-01-24

    Methane adsorption into the metal-organic framework (MOF) HKUST-1 and the resulting heat generation and dissipation are investigated using molecular dynamics simulations. Transient simulations reveal that thermal transport in the MOF occurs two orders of magnitude faster than gas diffusion. A large thermal resistance at the MOF-gas interface (equivalent to 127 nm of bulk HKUST-1), however, prevents fast release of the generated heat. The mass transport resistance at the MOF-gas interface is equivalent to 1 nm of bulk HKUST-1 and does not present a bottleneck in the adsorption process. These results provide important insights into the application of MOFs for gas storage applications.

  8. Computer codes for three dimensional mass transport with non-linear sorption

    International Nuclear Information System (INIS)

    Noy, D.J.

    1985-03-01

    The report describes the mathematical background and data input to finite element programs for three dimensional mass transport in a porous medium. The transport equations are developed and sorption processes are included in a general way so that non-linear equilibrium relations can be introduced. The programs are described and a guide given to the construction of the required input data sets. Concluding remarks indicate that the calculations require substantial computer resources and suggest that comprehensive preliminary analysis with lower dimensional codes would be important in the assessment of field data. (author)

  9. Effects of reservoir heterogeneity on scaling of effective mass transfer coefficient for solute transport

    Science.gov (United States)

    Leung, Juliana Y.; Srinivasan, Sanjay

    2016-09-01

    Modeling transport process at large scale requires proper scale-up of subsurface heterogeneity and an understanding of its interaction with the underlying transport mechanisms. A technique based on volume averaging is applied to quantitatively assess the scaling characteristics of effective mass transfer coefficient in heterogeneous reservoir models. The effective mass transfer coefficient represents the combined contribution from diffusion and dispersion to the transport of non-reactive solute particles within a fluid phase. Although treatment of transport problems with the volume averaging technique has been published in the past, application to geological systems exhibiting realistic spatial variability remains a challenge. Previously, the authors developed a new procedure where results from a fine-scale numerical flow simulation reflecting the full physics of the transport process albeit over a sub-volume of the reservoir are integrated with the volume averaging technique to provide effective description of transport properties. The procedure is extended such that spatial averaging is performed at the local-heterogeneity scale. In this paper, the transport of a passive (non-reactive) solute is simulated on multiple reservoir models exhibiting different patterns of heterogeneities, and the scaling behavior of effective mass transfer coefficient (Keff) is examined and compared. One such set of models exhibit power-law (fractal) characteristics, and the variability of dispersion and Keff with scale is in good agreement with analytical expressions described in the literature. This work offers an insight into the impacts of heterogeneity on the scaling of effective transport parameters. A key finding is that spatial heterogeneity models with similar univariate and bivariate statistics may exhibit different scaling characteristics because of the influence of higher order statistics. More mixing is observed in the channelized models with higher-order continuity. It

  10. Gluon transport equation with effective mass and dynamical onset of Bose–Einstein condensation

    International Nuclear Information System (INIS)

    Blaizot, Jean-Paul; Jiang, Yin; Liao, Jinfeng

    2016-01-01

    We study the transport equation describing a dense system of gluons, in the small scattering angle approximation, taking into account medium-generated effective masses of the gluons. We focus on the case of overpopulated systems that are driven to Bose–Einstein condensation on their way to thermalization. The presence of a mass modifies the dispersion relation of the gluon, as compared to the massless case, but it is shown that this does not change qualitatively the scaling behavior in the vicinity of the onset.

  11. Interfacial instabilities in vibrated fluids

    Science.gov (United States)

    Porter, Jeff; Laverón-Simavilla, Ana; Tinao Perez-Miravete, Ignacio; Fernandez Fraile, Jose Javier

    2016-07-01

    Vibrations induce a range of different interfacial phenomena in fluid systems depending on the frequency and orientation of the forcing. With gravity, (large) interfaces are approximately flat and there is a qualitative difference between vertical and horizontal forcing. Sufficient vertical forcing produces subharmonic standing waves (Faraday waves) that extend over the whole interface. Horizontal forcing can excite both localized and extended interfacial phenomena. The vibrating solid boundaries act as wavemakers to excite traveling waves (or sloshing modes at low frequencies) but they also drive evanescent bulk modes whose oscillatory pressure gradient can parametrically excite subharmonic surface waves like cross-waves. Depending on the magnitude of the damping and the aspect ratio of the container, these locally generated surfaces waves may interact in the interior resulting in temporal modulation and other complex dynamics. In the case where the interface separates two fluids of different density in, for example, a rectangular container, the mass transfer due to vertical motion near the endwalls requires a counterflow in the interior region that can lead to a Kelvin-Helmholtz type instability and a ``frozen wave" pattern. In microgravity, the dominance of surface forces favors non-flat equilibrium configurations and the distinction between vertical and horizontal applied forcing can be lost. Hysteresis and multiplicity of solutions are more common, especially in non-wetting systems where disconnected (partial) volumes of fluid can be established. Furthermore, the vibrational field contributes a dynamic pressure term that competes with surface tension to select the (time averaged) shape of the surface. These new (quasi-static) surface configurations, known as vibroequilibria, can differ substantially from the hydrostatic state. There is a tendency for the interface to orient perpendicular to the vibrational axis and, in some cases, a bulge or cavity is induced

  12. A development of multi-Species mass transport model considering thermodynamic phase equilibrium

    DEFF Research Database (Denmark)

    Hosokawa, Yoshifumi; Yamada, Kazuo; Johannesson, Björn

    2008-01-01

    ) variation in solid-phase composition when using different types of cement, (ii) physicochemical evaluation of steel corrosion initiation behaviour by calculating the molar ratio of chloride ion to hydroxide ion [Cl]/[OH] in pore solution, (iii) complicated changes of solid-phase composition caused......In this paper, a multi-species mass transport model, which can predict time dependent variation of pore solution and solid-phase composition due to the mass transport into the hardened cement paste, has been developed. Since most of the multi-species models established previously, based...... on the Poisson-Nernst-Planck theory, did not involve the modeling of chemical process, it has been coupled to thermodynamic equilibrium model in this study. By the coupling of thermodynamic equilibrium model, the multi-species model could simulate many different behaviours in hardened cement paste such as: (i...

  13. Performance of intact and partially degraded concrete barriers in limiting mass transport

    International Nuclear Information System (INIS)

    Walton, J.C.

    1992-06-01

    Mass transport through concrete barriers and release rate from concrete vaults are quantitatively evaluated. The thorny issue of appropriate diffusion coefficients for use in performance assessment calculations is covered, with no ultimate solution found. Release from monolithic concrete vaults composed of concrete waste forms is estimated with a semi-analytical solution. A parametric study illustrates the importance of different parameters on release. A second situation of importance is the role of a concrete shell or vault placed around typical waste forms in limiting mass transport. In both situations, the primary factor controlling concrete performance is cracks. The implications of leaching behavior on likely groundwater concentrations is examined. Frequently, lower groundwater concentrations can be expected in the absence of engineered covers that reduce infiltration

  14. Traffic lanes for vehicles of mass public passenger transport on city streets

    Directory of Open Access Journals (Sweden)

    Gladović Pavle V.

    2015-01-01

    Full Text Available Some of the basic measures of regulating public mass passenger transport in a city network are the introduction and management of traffic lanes reserved for the public transportation. These traffic lanes are important for several reasons: faster moving and shorter travelling time for the vehicles, reducing operating costs, improving the safety, increasing passenger comfort, maintaining of the timetable quality, etc. In most cities, an intensive use of the public transport is concentrated in the morning and the afternoon peak period. The state of the public transport system during these periods is reflected in the crowds inside the vehicles, long vehicle queues at intersections and at bus stops, which cause congestion on the streets and result in delays of public transport vehicles. This paper provides an overview of the current situation on an example in the city of Belgrade. The capacity and the quality of service for the street surfaces reserved for the public transportation vehicles were analysed on the aforementioned example.

  15. Nanoparticle Traffic on Helical Tracks: Thermophoretic Mass Transport through Carbon Nanotubes

    DEFF Research Database (Denmark)

    Schoen, Philipp A.E.; Walther, Jens Honore; Arcidiacono, Salvatore

    2006-01-01

    Using molecular dynamics simulations, we demonstrate and quantify thermophoretic motion of solid gold nanoparticles inside carbon nanotubes subject to wall temperature gradients ranging from 0.4 to 25 K/nm. For temperature gradients below 1 K/nm, we find that the particles move "on tracks......" in a predictable fashion as they follow unique helical orbits depending on the geometry of the carbon nanotubes. These findings markedly advance our knowledge of mass transport mechanisms relevant to nanoscale applications....

  16. Facile synthesis of mesostructured ZSM-5 zeolite with enhanced mass transport and catalytic performances

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chao; Ren, Yanqun [School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Tianhe District, Guangzhou 510641 (China); Gou, Jinsheng [College Material Science and Technology, Beijing Forestry University, Key Laboratory of Wooden Material Science and Application, Ministry of Education, 35 Tsinghua East Road, Haidian District, Beijing 100083 (China); Liu, Baoyu [School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Tianhe District, Guangzhou 510641 (China); Xi, Hongxia, E-mail: cehxxi@scut.edu.cn [School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Tianhe District, Guangzhou 510641 (China)

    2017-01-15

    Highlights: • A mesostructured MFI zeolite was synthesized via dual-functional surfactant approach. • Mass transport was investigated by applying zero length column technique. • The catalyst exhibited excellent catalytic activity and long lifetime. • Gaussian DFT was employed to study the role of surfactant in crystallization process. - Abstract: A mesostructured ZSM-5 zeolite with multilamellar structure was successfully synthesized by employing a tetra-headgroup rigid bolaform quaternary ammonium surfactant. It was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherms, amines temperature programmed desorption (amines-TPD), and computer simulation. These results indicated that the dual-functional amphiphilic surfactants play a critical role for directing the multilamellar structure with high mesoporosity. The mass transport and catalytic performances of the zeolite were investigated by zero length column (ZLC) technique and aldol condensation reactions to evaluate the structure-property relationship. These results clearly indicated that the mass transport of selected molecules in hierarchical zeolite can be accelerated by introducing mesoporous structure with mesostructure with reduced diffusion length and an overall enhanced resistance against deactivation in reactions involving large molecules. Furthermore, the dual-functional surfactant approach of making hierarchical zeolite with MFI nanosheets framework would open up new opportunities for design and synthesis of hierarchical zeolites with controllable mesoporous structures.

  17. The Impact of Microstructure Geometry on the Mass Transport in Artificial Pores: A Numerical Approach

    Directory of Open Access Journals (Sweden)

    Matthias Galinsky

    2014-01-01

    Full Text Available The microstructure of porous materials used in heterogeneous catalysis determines the mass transport inside networks, which may vary over many length scales. The theoretical prediction of mass transport phenomena in porous materials, however, is incomplete and is still not completely understood. Therefore, experimental data for every specific porous system is needed. One possible experimental technique for characterizing the mass transport in such pore networks is pulse experiments. The general evaluation of experimental outcomes of these techniques follows the solution of Fick’s second law where an integral and effective diffusion coefficient is recognized. However, a detailed local understanding of diffusion and sorption processes remains a challenge. As there is lack of proved models covering different length scales, existing classical concepts need to be evaluated with respect to their ability to reflect local geometries on the nanometer level. In this study, DSMC (Direct Simulation Monte Carlo models were used to investigate the impact of pore microstructures on the diffusion behaviour of gases. It can be understood as a virtual pulse experiment within a single pore or a combination of different pore geometries.

  18. The influence of mass transfer on solute transport in column experiments with an aggregated soil

    Science.gov (United States)

    Roberts, Paul V.; Goltz, Mark N.; Summers, R. Scott; Crittenden, John C.; Nkedi-Kizza, Peter

    1987-06-01

    The spreading of concentration fronts in dynamic column experiments conducted with a porous, aggregated soil is analyzed by means of a previously documented transport model (DFPSDM) that accounts for longitudinal dispersion, external mass transfer in the boundary layer surrounding the aggregate particles, and diffusion in the intra-aggregate pores. The data are drawn from a previous report on the transport of tritiated water, chloride, and calcium ion in a column filled with Ione soil having an average aggregate particle diameter of 0.34 cm, at pore water velocities from 3 to 143 cm/h. The parameters for dispersion, external mass transfer, and internal diffusion were predicted for the experimental conditions by means of generalized correlations, independent of the column data. The predicted degree of solute front-spreading agreed well with the experimental observations. Consistent with the aggregate porosity of 45%, the tortuosity factor for internal pore diffusion was approximately equal to 2. Quantitative criteria for the spreading influence of the three mechanisms are evaluated with respect to the column data. Hydrodynamic dispersion is thought to have governed the front shape in the experiments at low velocity, and internal pore diffusion is believed to have dominated at high velocity; the external mass transfer resistance played a minor role under all conditions. A transport model such as DFPSDM is useful for interpreting column data with regard to the mechanisms controlling concentration front dynamics, but care must be exercised to avoid confounding the effects of the relevant processes.

  19. Facile synthesis of mesostructured ZSM-5 zeolite with enhanced mass transport and catalytic performances

    International Nuclear Information System (INIS)

    Li, Chao; Ren, Yanqun; Gou, Jinsheng; Liu, Baoyu; Xi, Hongxia

    2017-01-01

    Highlights: • A mesostructured MFI zeolite was synthesized via dual-functional surfactant approach. • Mass transport was investigated by applying zero length column technique. • The catalyst exhibited excellent catalytic activity and long lifetime. • Gaussian DFT was employed to study the role of surfactant in crystallization process. - Abstract: A mesostructured ZSM-5 zeolite with multilamellar structure was successfully synthesized by employing a tetra-headgroup rigid bolaform quaternary ammonium surfactant. It was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherms, amines temperature programmed desorption (amines-TPD), and computer simulation. These results indicated that the dual-functional amphiphilic surfactants play a critical role for directing the multilamellar structure with high mesoporosity. The mass transport and catalytic performances of the zeolite were investigated by zero length column (ZLC) technique and aldol condensation reactions to evaluate the structure-property relationship. These results clearly indicated that the mass transport of selected molecules in hierarchical zeolite can be accelerated by introducing mesoporous structure with mesostructure with reduced diffusion length and an overall enhanced resistance against deactivation in reactions involving large molecules. Furthermore, the dual-functional surfactant approach of making hierarchical zeolite with MFI nanosheets framework would open up new opportunities for design and synthesis of hierarchical zeolites with controllable mesoporous structures.

  20. Iridium Interfacial Stack (IRIS)

    Science.gov (United States)

    Spry, David James (Inventor)

    2015-01-01

    An iridium interfacial stack ("IrIS") and a method for producing the same are provided. The IrIS may include ordered layers of TaSi.sub.2, platinum, iridium, and platinum, and may be placed on top of a titanium layer and a silicon carbide layer. The IrIS may prevent, reduce, or mitigate against diffusion of elements such as oxygen, platinum, and gold through at least some of its layers.

  1. Interfacial structures in downward two-phase bubbly flow

    International Nuclear Information System (INIS)

    Paranjape, S.S.; Kim, S.; Ishii, M.; Kelly, J.

    2003-01-01

    Downward two-phase flow was studied considering its significance in view of Light Water Reactor Accidents (LWR) such as Loss of Heat Sink (LOHS) by feed water loss or secondary pipe break. The flow studied, was an adiabatic, air-water, co-current, vertically downward two-phase flow. The experimental test sections had internal hydraulic diameters of 25.4 mm and 50.8 mm. Flow regime map was obtained using the characteristic signals obtained from an impedance void meter, employing neural network based identification methodology to minimize the subjective judgment in determining the flow regimes. A four sensor conductivity probe was used to measure the local two phase flow parameters, which characterize the interfacial structures. The local time averaged two-phase flow parameters measured were: void fraction (α), interfacial area concentration (a i ), bubble velocity (v g ), and Sauter mean diameter (D Sm ). The flow conditions were from the bubbly flow regime. The local profiles of these parameters as well as their axial development revealed the nature of the interfacial structures and the bubble interaction mechanisms occurring in the flow. Furthermore, this study provided a good database for the development of the interfacial area transport equation, which dynamically models the changes in the interfacial area along the flow field. An interfacial area transport equation was developed for downward flow based on that developed for the upward flow, with certain modifications in the bubble interaction terms. The area averaged values of the interfacial area concentration were compared with those predicted by the interfacial area transport model. (author)

  2. Wave-induced mass transport affects daily Escherichia coli fluctuations in nearshore water

    Science.gov (United States)

    Ge, Zhongfu; Whitman, Richard L.; Nevers, Meredith B.; Phanikumar, Mantha S.

    2012-01-01

    Characterization of diel variability of fecal indicator bacteria concentration in nearshore waters is of particular importance for development of water sampling standards and protection of public health. Significant nighttime increase in Escherichia coli (E. coli) concentration in beach water, previously observed at marine sites, has also been identified in summer 2000 from fixed locations in waist- and knee-deep waters at Chicago 63rd Street Beach, an embayed, tideless, freshwater beach with low currents at night (approximately 0.015 m s–1). A theoretical model using wave-induced mass transport velocity for advection was developed to assess the contribution of surface waves to the observed nighttime E. coli replenishment in the nearshore water. Using average wave conditions for the summer season of year 2000, the model predicted an amount of E. coli transported from water of intermediate depth, where sediment resuspension occurred intermittently, that would be sufficient to have elevated E. coli concentration in the surf and swash zones as observed. The nighttime replenishment of E. coli in the surf and swash zones revealed here is an important phase in the cycle of diel variations of E. coli concentration in nearshore water. According to previous findings in Ge et al. (Environ. Sci. Technol. 2010, 44, 6731–6737), enhanced current circulation in the embayment during the day tends to displace and deposit material offshore, which partially sets up the system by the early evening for a new period of nighttime onshore movement. This wave-induced mass transport effect, although facilitating a significant base supply of material shoreward, can be perturbed or significantly influenced by high currents (orders of magnitude larger than a typical wave-induced mass transport velocity), current-induced turbulence, and tidal forcing.

  3. Coupled porohyperelastic mass transport (PHEXPT) finite element models for soft tissues using ABAQUS.

    Science.gov (United States)

    Vande Geest, Jonathan P; Simon, B R; Rigby, Paul H; Newberg, Tyler P

    2011-04-01

    Finite element models (FEMs) including characteristic large deformations in highly nonlinear materials (hyperelasticity and coupled diffusive/convective transport of neutral mobile species) will allow quantitative study of in vivo tissues. Such FEMs will provide basic understanding of normal and pathological tissue responses and lead to optimization of local drug delivery strategies. We present a coupled porohyperelastic mass transport (PHEXPT) finite element approach developed using a commercially available ABAQUS finite element software. The PHEXPT transient simulations are based on sequential solution of the porohyperelastic (PHE) and mass transport (XPT) problems where an Eulerian PHE FEM is coupled to a Lagrangian XPT FEM using a custom-written FORTRAN program. The PHEXPT theoretical background is derived in the context of porous media transport theory and extended to ABAQUS finite element formulations. The essential assumptions needed in order to use ABAQUS are clearly identified in the derivation. Representative benchmark finite element simulations are provided along with analytical solutions (when appropriate). These simulations demonstrate the differences in transient and steady state responses including finite deformations, total stress, fluid pressure, relative fluid, and mobile species flux. A detailed description of important model considerations (e.g., material property functions and jump discontinuities at material interfaces) is also presented in the context of finite deformations. The ABAQUS-based PHEXPT approach enables the use of the available ABAQUS capabilities (interactive FEM mesh generation, finite element libraries, nonlinear material laws, pre- and postprocessing, etc.). PHEXPT FEMs can be used to simulate the transport of a relatively large neutral species (negligible osmotic fluid flux) in highly deformable hydrated soft tissues and tissue-engineered materials.

  4. Study of Bubble Size, Void Fraction, and Mass Transport in a Bubble Column under High Amplitude Vibration

    Directory of Open Access Journals (Sweden)

    Shahrouz Mohagheghian

    2018-04-01

    Full Text Available Vertical vibration is known to cause bubble breakup, clustering and retardation in gas-liquid systems. In a bubble column, vibration increases the mass transfer ratio by increasing the residence time and phase interfacial area through introducing kinetic buoyancy force (Bjerknes effect and bubble breakup. Previous studies have explored the effect of vibration frequency (f, but minimal effort has focused on the effect of amplitude (A on mass transfer intensification. Thus, the current work experimentally examines bubble size, void fraction, and mass transfer in a bubble column under relatively high amplitude vibration (1.5 mm < A <9.5 mm over a frequency range of 7.5–22.5 Hz. Results of the present work were compared with past studies. The maximum stable bubble size under vibration was scaled using Hinze theory for breakage. Results of this work indicate that vibration frequency exhibits local maxima in both mass transfer and void fraction. Moreover, an optimum amplitude that is independent of vibration frequency was found for mass transfer enhancements. Finally, this work suggests physics-based models to predict void fraction and mass transfer in a vibrating bubble column.

  5. Interfacial effects in a multistage mixer-settler operation

    International Nuclear Information System (INIS)

    Jiinshiung Horng; Daluh Lu; Yingchu Hoh

    1988-01-01

    A pilot-scale mixer-settler with twenty-one stages was used to investigate the interfacial tension change during extraction cycle for the complicated system: NdCl 3 -SmCl 3 -EuCl 3 -GdCl 3 -TbCl 3 -DyCl 3 -HCl- 1 M D2EHPA-kerosene. Interfacial tension, total rare earth (TRE) concentrations in both phases, aqueous acidities, and organic entrainment in the raffinate, etc., were measured for each stage. Murphree stage efficiencies based on organic phase were calculated and related to the interfacial tension profiles. In general, the lower the interfacial tension, the higher the stage efficiency observed. For the extraction section, the stage efficiency ranged from 80% - 100%, but for stripping (including scrubbing) section, it varied from 100% - 15%. For high acidic stripping agent, 5 M HCl, the relatively lower stage efficiency might be due to the protonation of the acidic extractant, therefore the interfacial resistance increased significantly. From the information of stage efficiency, mass transfer direction, and interfacial tension versus solute concentration etc., the Marangoni effect could be used to explain the interfacial phenomena of this complicated extraction system. The results of real stream tests in this investigation will be useful in future plant design. (author)

  6. The Sedimentology and Origins of a Giant Mass Transport Deposit: The Nataraja Slide, Arabian Sea

    Science.gov (United States)

    Dailey, S. K.; Clift, P. D.; Kulhanek, D. K.; Calves, G.

    2017-12-01

    The Nataraja Slide was recently discovered by seismic mapping off the west coast of India in the Arabian Sea. Volumetrically estimated to be 19,000 km3, it is the second largest mass transport deposit known on a passive margin. Understanding how this deposit was emplaced is important to constrain how mass wasting affects the bathymetry of sedimentary basins, as well as the effects triggered by such a large event, including tsunamis. The Nataraja Slide was emplaced at 10.8 Ma as a result of collapse of the western India margin, which traveled 550 km into the basin. The deposit has been cored in two locations by the International Ocean Discovery Program (IODP) Expedition 355, where it is 330 m (Site U1456) and 190 m thick (Site U1457). The presence of various deformation structures and the occurrence of a predominantly reworked calcareous nannofossil assemblages are used to define the top of the deposit. The deposit appears to consist of two units at Site U1456 with 22 m of upper Miocene hemipelagic sediment separating them, suggesting emplacement in two large pulses. At both sites, the mass transport deposit has a coarse carbonate-dominated base, composed of clast-supported breccia overlain by massive calcarenite associated with high-energy current transport, and calcilutite. These strata are overlain by steeply inclined, slumped but otherwise coherent pyritized, siliciclastic mudstones and minor volumes of matrix-supported conglomerates, interpreted as debris flows. Emplacement appears to have eroded significant thicknesses of Indus Fan turbidites at Site U1456, as there is a hiatus that is a minimum of 2.5 m.y. at the base. At Site U1457, the slide directly overlies Paleocene reddish mudstones on the eastern flank of the Laxmi Ridge, which likely diverted the sediment to the south in the Laxmi Basin and away from the main Arabian Sea basin. Bulk sediment Nd and Sr isotope geochemistry show a provenance, similar to those of the Tapti and Narmada rivers in western

  7. Interfacial Engineering of Perovskite Solar Cells by Employing a Hydrophobic Copper Phthalocyanine Derivative as Hole-Transporting Material with Improved Performance and Stability.

    Science.gov (United States)

    Jiang, Xiaoqing; Yu, Ze; Lai, Jianbo; Zhang, Yuchen; Hu, Maowei; Lei, Ning; Wang, Dongping; Yang, Xichuan; Sun, Licheng

    2017-04-22

    In high-performance perovskite solar cells (PSCs), hole-transporting materials (HTMs) play an important role in extracting and transporting the photo-generated holes from the perovskite absorber to the cathode, thus reducing unwanted recombination losses and enhancing the photovoltaic performance. Herein, solution-processable tetra-4-(bis(4-tert-butylphenyl)amino)phenoxy-substituted copper phthalocyanine (CuPc-OTPAtBu) was synthesized and explored as a HTM in PSCs. The optical, electrochemical, and thermal properties were fully characterized for this organic metal complex. The photovoltaic performance of PSCs employing this CuPc derivative as a HTM was further investigated, in combination with a mixed-ion perovskite as a light absorber and a low-cost vacuum-free carbon as cathode. The optimized devices [doped with 6 % (w/w) tetrafluoro-tetracyano-quinodimethane (F4TCNQ)] showed a decent power conversion efficiency of 15.0 %, with an open-circuit voltage of 1.01 V, a short-circuit current density of 21.9 mA cm -2 , and a fill factor of 0.68. Notably, the PSC devices studied also exhibited excellent long-term durability under ambient condition for 720 h, mainly owing to the introduction of the hydrophobic HTM interlayer, which prevents moisture penetration into the perovskite film. The present work emphasizes that solution-processable CuPc holds a great promise as a class of alternative HTMs that can be further explored for efficient and stable PSCs in the future. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Pore-scale investigation of mass transport and electrochemistry in a solid oxide fuel cell anode

    Energy Technology Data Exchange (ETDEWEB)

    Grew, Kyle N.; Joshi, Abhijit S.; Peracchio, Aldo A.; Chiu, Wilson K.S. [Department of Mechanical Engineering, University of Connecticut, 191 Auditorium Road, Storrs, CT 06269-3139 (United States)

    2010-04-15

    The development and validation of a model for the study of pore-scale transport phenomena and electrochemistry in a Solid Oxide Fuel Cell (SOFC) anode are presented in this work. This model couples mass transport processes with a detailed reaction mechanism, which is used to model the electrochemical oxidation kinetics. Detailed electrochemical oxidation reaction kinetics, which is known to occur in the vicinity of the three-phase boundary (TPB) interfaces, is discretely considered in this work. The TPB regions connect percolating regions of electronic and ionic conducting phases of the anode, nickel (Ni) and yttria-stabilized zirconia (YSZ), respectively; with porous regions supporting mass transport of the fuel and product. A two-dimensional (2D), multi-species lattice Boltzmann method (LBM) is used to describe the diffusion process in complex pore structures that are representative of the SOFC anode. This diffusion model is discretely coupled to a kinetic electrochemical oxidation mechanism using localized flux boundary conditions. The details of the oxidation kinetics are prescribed as a function of applied activation overpotential and the localized hydrogen and water mole fractions. This development effort is aimed at understanding the effects of the anode microstructure within TPB regions. This work describes the methods used so that future studies can consider the details of SOFC anode microstructure. (author)

  9. Mass-corrections for the conservative coupling of flow and transport on collocated meshes

    Energy Technology Data Exchange (ETDEWEB)

    Waluga, Christian, E-mail: waluga@ma.tum.de [Institute for Numerical Mathematics (M2), Technische Universität München, Boltzmannstraße 3, D-85748 Garching bei München (Germany); Wohlmuth, Barbara [Institute for Numerical Mathematics (M2), Technische Universität München, Boltzmannstraße 3, D-85748 Garching bei München (Germany); Rüde, Ulrich [Department of Computer Science 10, University Erlangen–Nuremberg, Cauerstr. 11, D-91058 Erlangen (Germany)

    2016-01-15

    Buoyancy-driven flow models demand a careful treatment of the mass-balance equation to avoid spurious source and sink terms in the non-linear coupling between flow and transport. In the context of finite-elements, it is therefore commonly proposed to employ sufficiently rich pressure spaces, containing piecewise constant shape functions to obtain local or even strong mass-conservation. In three-dimensional computations, this usually requires nonconforming approaches, special meshes or higher order velocities, which make these schemes prohibitively expensive for some applications and complicate the implementation into legacy code. In this paper, we therefore propose a lean and conservatively coupled scheme based on standard stabilized linear equal-order finite elements for the Stokes part and vertex-centered finite volumes for the energy equation. We show that in a weak mass-balance it is possible to recover exact conservation properties by a local flux-correction which can be computed efficiently on the control volume boundaries of the transport mesh. We discuss implementation aspects and demonstrate the effectiveness of the flux-correction by different two- and three-dimensional examples which are motivated by geophysical applications.

  10. The Interfacial Thermal Conductance of Epitaxial Metal-Semiconductor Interfaces

    Science.gov (United States)

    Ye, Ning

    -silicon), interfaces with varying levels of disorder (epitaxial and non-epitaxial). The ITC values of silicides-silicon interfaces observed in this study are higher than those of other metallic interfaces to Si found in literature. Most surprisingly, it is experimentally found that ITC values are independent of interfacial quality and substrate orientation. Computationally, it is found that the non-equilibrium atomistic Green's Function technique (NEGF), which is specically designed to simulate coherent elastic phonon transport across interfaces, significantly underpredicts ITC values for CoSi2-Si interfaces, suggesting that energy transport does not occur purely by coherent transmission of phonons, even for epitaxial interfaces. In contrast, the Diffuse Mismatch Model closely mimics the experimentally observed ITC values for CoSi 2-Si, NiSi-Si and TiSi2-Si interfaces, and only slightly overestimating the same for PtSi-Si interfaces. Furthermore, the results also show that ITC is independent of degenerate doping up to doping levels of ≈1 x 1019 cm-3, indicating there is no significant direct electronic transport or transport effects which depend on long-range metal-semiconductor band alignment. Then, I study the effect of phonon band structure on ITC through measurements of epitaxial NiAl1-xGax-GaAs interfaces for varying levels of alloy composition, which independently tunes the mass of the metal's heavy atom without much affect on the lattice structure or interatomic force constants. The ITC values are found to linearly increase with increasing Ga content, consistent with the disappearance of a phonon band gap in NiAl 1-xGax films with increasing Ga content, which enhances the phonon transmission coefficients due to a better density of states overlap between the two (NiAl1-xGax, GaAs) materials. Finally, I study a unique subset of epitaxial rocksalt interfaces between the Group IV metal nitrides (TiN, ZrN, and HfN) to MgO substrates as well as ScN layers. Prior to the currrent

  11. Interfacial solvation thermodynamics

    International Nuclear Information System (INIS)

    Ben-Amotz, Dor

    2016-01-01

    Previous studies have reached conflicting conclusions regarding the interplay of cavity formation, polarizability, desolvation, and surface capillary waves in driving the interfacial adsorptions of ions and molecules at air–water interfaces. Here we revisit these questions by combining exact potential distribution results with linear response theory and other physically motivated approximations. The results highlight both exact and approximate compensation relations pertaining to direct (solute–solvent) and indirect (solvent–solvent) contributions to adsorption thermodynamics, of relevance to solvation at air–water interfaces, as well as a broader class of processes linked to the mean force potential between ions, molecules, nanoparticles, proteins, and biological assemblies. (paper)

  12. Ion-neutral transport through quadrupole interfaces of mass-spectrometer systems

    International Nuclear Information System (INIS)

    Jugroot, M.; Groth, C.P.T.; Thomson, B.A.; Baranov, V.; Collings, B.A.; French, J.B.

    2004-01-01

    The transport of free ions through highly under-expanded jet flows of neutral gases and in the presence of applied electric fields is investigated by continuum-based numerical simulations. In particular, numerical results are described which are relevant to ion flows occurring in quadrupole interfaces of mass spectrometer systems. A five-moment mathematical model and parallel multi-block numerical solution procedure is developed for predicting the ion transport. The model incorporates the effects of ion-neutral collision processes and is used in conjunction with a Navier-Stokes model and flow solver for the neutral gas to examine the key influences controlling the ion motion. The effects of the neutral gas flow, electric fields (both dc and rf), and flow field geometry on ion mobility are carefully assessed. The capability of controlling the charged particle motions through a combination of directed neutral flow and applied electric field is demonstrated for these high-speed, hypersonic, jet flows. (author)

  13. Effective Heat and Mass Transport Properties of Anisotropic Porous Ceria for Solar Thermochemical Fuel Generation

    Directory of Open Access Journals (Sweden)

    Sophia Haussener

    2012-01-01

    Full Text Available High-resolution X-ray computed tomography is employed to obtain the exact 3D geometrical configuration of porous anisotropic ceria applied in solar-driven thermochemical cycles for splitting H2O and CO2. The tomography data are, in turn, used in direct pore-level numerical simulations for determining the morphological and effective heat/mass transport properties of porous ceria, namely: porosity, specific surface area, pore size distribution, extinction coefficient, thermal conductivity, convective heat transfer coefficient, permeability, Dupuit-Forchheimer coefficient, and tortuosity and residence time distributions. Tailored foam designs for enhanced transport properties are examined by means of adjusting morphologies of artificial ceria samples composed of bimodal distributed overlapping transparent spheres in an opaque medium.

  14. A mercury transport and fate model (LM2-mercury) for mass budget assessment of mercury cycling in Lake Michigan

    Science.gov (United States)

    LM2-Mercury, a mercury mass balance model, was developed to simulate and evaluate the transport, fate, and biogeochemical transformations of mercury in Lake Michigan. The model simulates total suspended solids (TSS), disolved organic carbon (DOC), and total, elemental, divalent, ...

  15. Eutectic fusion used for the survey of transport of mass in metallic solutions

    International Nuclear Information System (INIS)

    Savane, Y.S.; Katty, S.; Balde, M.L.; Cisse, S.; Rogov, V.I.

    1997-09-01

    The phenomenon of eutectic fusion could be used for the survey of transport of mass in metallic solutions, which allows to determine the part of the ionic conductibility in the solutions. The survey done in the system In 2 Bi Bi-In at a temperature of 72 deg. C with a current of 4A allowed to find a ionic current of 2,6.10 -3 which constitutes about 0,07% of the total current. So the part of ionic conductibility in the eutectic fusion of the system In 2 Bi Bi-In is of 0,07%. (author)

  16. Identification of biomolecule mass transport and binding rate parameters in living cells by inverse modeling

    Directory of Open Access Journals (Sweden)

    Shirmohammadi Adel

    2006-10-01

    Full Text Available Abstract Background Quantification of in-vivo biomolecule mass transport and reaction rate parameters from experimental data obtained by Fluorescence Recovery after Photobleaching (FRAP is becoming more important. Methods and results The Osborne-Moré extended version of the Levenberg-Marquardt optimization algorithm was coupled with the experimental data obtained by the Fluorescence Recovery after Photobleaching (FRAP protocol, and the numerical solution of a set of two partial differential equations governing macromolecule mass transport and reaction in living cells, to inversely estimate optimized values of the molecular diffusion coefficient and binding rate parameters of GFP-tagged glucocorticoid receptor. The results indicate that the FRAP protocol provides enough information to estimate one parameter uniquely using a nonlinear optimization technique. Coupling FRAP experimental data with the inverse modeling strategy, one can also uniquely estimate the individual values of the binding rate coefficients if the molecular diffusion coefficient is known. One can also simultaneously estimate the dissociation rate parameter and molecular diffusion coefficient given the pseudo-association rate parameter is known. However, the protocol provides insufficient information for unique simultaneous estimation of three parameters (diffusion coefficient and binding rate parameters owing to the high intercorrelation between the molecular diffusion coefficient and pseudo-association rate parameter. Attempts to estimate macromolecule mass transport and binding rate parameters simultaneously from FRAP data result in misleading conclusions regarding concentrations of free macromolecule and bound complex inside the cell, average binding time per vacant site, average time for diffusion of macromolecules from one site to the next, and slow or rapid mobility of biomolecules in cells. Conclusion To obtain unique values for molecular diffusion coefficient and

  17. Study of point defects in non crystalline alloys by high temperature mass transport experiments

    International Nuclear Information System (INIS)

    Limoge, Y.

    1986-09-01

    We present in this communication the results of new experiments designed to study the mass transport mechanism in non-crystalline metallic alloys. They are based on the isothermal measurement of the crystallization kinetics, either without constraint or under electron irradiation or hydrostatic pressure. These experiments show that in the alloys studied, (FeNi) 8 (Pb) 2 and Ni 6 Nb 4 ), irradiation enhances the diffusion on the one hand, and on the other that there exist an activation volume for diffusion, of the order of one atomic volume. We discuss then the atomic model of diffusion needed to explain our results

  18. Interannual variability of mass transport in the Canary region from LADCP data

    Science.gov (United States)

    Comas-Rodríguez, Isis; Hernández-Guerra, Alonso; Vélez-Belchí, Pedro; Fraile-Nuez, Eugenio

    2010-05-01

    The variability of the Canary Current is a widely studied topic regarding its role as eastern boundary of the North Atlantic Subtropical Gyre. The Canary region provides indeed an interesting study area in terms of estimating variability scales of the Subtropical Gyre as well as the water masses dynamics. RAPROCAN (RAdial PROfunda de CANarias - Canary deep hydrographic section) is a project based on the reaching of these goals through the obtaining of hydrographic measures during cruises taking place approximately along 29°N, to the North of the Canary Archipelago, twice a year since 2006. The full depth sampling carried out allows the study of temperature and salinity distribution and the calculation of mass transports across the section. The transport estimates are compared to those obtained from previous measurements and estimates in the region. Therefore, transports and their variability through the last decade are quantified. The most significant advance made to previous works is the use of LADCP (Lowered Acoustic Doppler Current Profiler) data informing the initial geostrophic calculations. Thus, corrections are applied to each geostrophic profile considering the reference velocity obtained from LADCP data. ADCP-referenced transport estimates are obtained, providing a successful comparison between the velocity fields obtained from the hydrographic measures. While this work shows the interannual variability observed in winter since 1997, preliminary results confirm previous hypotheses about the magnitude of the Canary Current. Those results including LADCP data also provide new aspects in the circulation distribution across the Canary Archipelago. Also moored current meter data were taken into account in the up close study of the Current through the Lanzarote Passage. Interesting conclusions were drawn that certify the usefulness of LADCP data in referencing geostrophic calculations, while corroborating the results obtained through this methodology. Hence

  19. Numerical simulation of mass and energy transport phenomena in solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Arpino, F. [Dipartimento di Meccanica, Strutture, Ambiente e Territorio (DiMSAT), University of Cassino, via Di Biasio 43, Cassino (Italy); Massarotti, N. [Dipertimento per le Tecnologie (DiT), University of Naples ' ' Parthenope' ' , Centro Direzionale, isola C4, 80143 Napoli (Italy)

    2009-12-15

    Solid Oxide Fuel Cells (SOFCs) represent a very promising technology for near future energy conversion thanks to a number of advantages, including the possibility of using different fuels. In this paper, a detailed numerical model, based on a general mathematical description and on a finite element Characteristic based Split (CBS) algorithm code is employed to simulate mass and energy transport phenomena in SOFCs. The model predicts the thermodynamic quantity of interest in the fuel cell. Full details of the numerical solution obtained are presented both in terms of heat and mass transfer in the cell and in terms of electro-chemical reactions that occur in the system considered. The results obtained with the present algorithm is compared with the experimental data available in the literature for validation, showing an excellent agreement. (author)

  20. Submarine Landslides and Mass-Transport Deposition in the Nankai fore-arc

    Science.gov (United States)

    Strasser, M.; Henry, P.; Kanamatsu, T.; Moe, K.; Moore, G. F.; IODP Expedition 333 Scientists

    2011-12-01

    Multiple lines of evidence exist for a range of sediment mass movement processes within the shallow megasplay fault zone (MSFZ) area and the adjacent slope basin in the outer fore-arc of the Nankai subduction zone, Japan. Diagnostic features observed in 3-D reflection seismic data and in cores from Integrated Ocean Drilling Program (IODP) Expedition 316 document a complex mass movement history spanning at least ˜2.87 million years. Various modes and scales of sediment remobilization can be related to the different morphotectonic settings in which they occurred and allow integration of knowledge on the spatial and temporal distribution of submarine landslides into a holistic reconstruction of the tectonostratigraphic evolution. New data from the most-recent Nankai IODP Expedition 333, which drilled and cored a Pleistocene-to-Holocene succession of the slope-basin seaward of the MSFZ, provides unprecedented details on submarine landslide processes occurring over the last Million year. The slope-basin represents the depocentre for downslope sediment transport and is characterized in 3-D reflection seismic data by several mass-transport deposits (MTDs), including an up to 180 m thick MTD. Here we present D/V Chikyu shipboard results and first post cruise results from Site C0018, including litho- bio- magneto- tephra- and stable isotope-stratigraphy, X-ray computed tomography analysis and physical properties data. Six MTDs were identified from visual core description and X-ray CT-scans. The thickest MTD is also the oldest (emplaced between 0.85 and 1.05 Ma) and it coincides with a lithological transition between a sandy turbidite sequence below, and ash-bearing hemipelagites comprising several MTDs above. Deformation styles within the MTD are heterogeneous: intervals of disturbed sediments are interbedded within intervals inferred to retain original, coherent bedding. In three occurrences the base of the MTD is defined by a shear zone within fine-grained sediments

  1. New particle formation in air mass transported between two measurement sites in Northern Finland

    Directory of Open Access Journals (Sweden)

    M. Komppula

    2006-01-01

    Full Text Available This study covers four years of aerosol number size distribution data from Pallas and Värriö sites 250 km apart from each other in Northern Finland and compares new particle formation events between these sites. In air masses of eastern origin almost all events were observed to start earlier at the eastern station Värriö, whereas in air masses of western origin most of the events were observed to start earlier at the western station Pallas. This demonstrates that particle formation in a certain air mass type depends not only on the diurnal variation of the parameters causing the phenomenon (such as photochemistry but also on some properties carried by the air mass itself. The correlation in growth rates between the two sites was relatively good, which suggests that the amount of condensable vapour causing the growth must have been at about the same level in both sites. The condensation sink was frequently much higher at the downwind station. It seems that secondary particle formation related to biogenic sources dominate in many cases over the particle sinks during the air mass transport between the sites. Two cases of transport from Pallas to Värriö were further analysed with an aerosol dynamics model. The model was able to reproduce the observed nucleation events 250 km down-wind at Värriö but revealed some differences between the two cases. The simulated nucleation rates were in both cases similar but the organic concentration profiles that best reproduced the observations were different in the two cases indicating that divergent formation reactions may dominate under different conditions. The simulations also suggested that organic compounds were the main contributor to new particle growth, which offers a tentative hypothesis to the distinct features of new particles at the two sites: Air masses arriving from the Atlantic Ocean typically spent approximately only ten hours over land before arriving at Pallas, and thus the time for the

  2. Mass gathering medicine: a predictive model for patient presentation and transport rates.

    Science.gov (United States)

    Arbon, P; Bridgewater, F H; Smith, C

    2001-01-01

    This paper reports on research into the influence of environmental factors (including crowd size, temperature, humidity, and venue type) on the number of patients and the patient problems presenting to first-aid services at large, public events in Australia. Regression models were developed to predict rates of patient presentation and of transportation-to-a-hospital for future mass gatherings. To develop a data set and predictive model that can be applied across venues and types of mass gathering events that is not venue or event specific. Data collected will allow informed event planning for future mass gatherings for which health care services are required. Mass gatherings were defined as public events attended by in excess of 25,000 people. Over a period of 12 months, 201 mass gatherings attended by a combined audience in excess of 12 million people were surveyed throughout Australia. The survey was undertaken by St. John Ambulance Australia personnel. The researchers collected data on the incidence and type of patients presenting for treatment and on the environmental factors that may influence these presentations. A standard reporting format and definition of event geography was employed to overcome the event-specific nature of many previous surveys. There are 11,956 patients in the sample. The patient presentation rate across all event types was 0.992/1,000 attendees, and the transportation-to-hospital rate was 0.027/1,000 persons in attendance. The rates of patient presentations declined slightly as crowd sizes increased. The weather (particularly the relative humidity) was related positively to an increase in the rates of presentations. Other factors that influenced the number and type of patients presenting were the mobility of the crowd, the availability of alcohol, the event being enclosed by a boundary, and the number of patient-care personnel on duty. Three regression models were developed to predict presentation rates at future events. Several

  3. Multicomponent mass transport model: theory and numerical implementation (discrete-parcel-random-walk version)

    International Nuclear Information System (INIS)

    Ahlstrom, S.W.; Foote, H.P.; Arnett, R.C.; Cole, C.R.; Serne, R.J.

    1977-05-01

    The Multicomponent Mass Transfer (MMT) Model is a generic computer code, currently in its third generation, that was developed to predict the movement of radiocontaminants in the saturated and unsaturated sediments of the Hanford Site. This model was designed to use the water movement patterns produced by the unsaturated and saturated flow models coupled with dispersion and soil-waste reaction submodels to predict contaminant transport. This report documents the theorical foundation and the numerical solution procedure of the current (third) generation of the MMT Model. The present model simulates mass transport processes using an analog referred to as the Discrete-Parcel-Random-Walk (DPRW) algorithm. The basic concepts of this solution technique are described and the advantages and disadvantages of the DPRW scheme are discussed in relation to more conventional numerical techniques such as the finite-difference and finite-element methods. Verification of the numerical algorithm is demonstrated by comparing model results with known closed-form solutions. A brief error and sensitivity analysis of the algorithm with respect to numerical parameters is also presented. A simulation of the tritium plume beneath the Hanford Site is included to illustrate the use of the model in a typical application. 32 figs

  4. Mass transport aspects of polymer electrolyte fuel cells under two-phase flow conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, D.

    2007-03-27

    This work deals with selected aspects of mass transport phenomena in PEFCs and DMFCs. Emphasis is placed on the implications originating from the occurrence of two-phase flow within these devices. Optimality of supply, distribution, and removal of the fuel, the oxidant, and the reaction products is of utmost importance for the stability, efficiency, and durability of the devices. Being a prerequisite for high current densities while maintaining sufficient voltage, mass transport optimization contributes to the development of cost effective as well as compact designs and hence competitive fuel cells. [German] Die Visualisierung und Quantifizierung von Fluessigwasseransammlungen in Polymerelektrolytmembran-Brennstoffzellen konnte mittels Neutronenradiographie erreicht werden. Dank dieser neuartigen diagnostischen Methode konnte erstmals die Fluessigwasseransammlung in den poroesen Gasdiffusionsschichten direkt nachgewiesen und quantifiziert werden. Die Kombination von Neutronenradiographie mit ortsaufgeloesten Stromdichtemessungen bzw. lokaler Impedanzspektroskopie erlaubte die Korrelation des inhomogenen Fluessigwasseranfalls mit dem lokalen elektrochemischen Leistungsverhalten. Systematische Untersuchungen an Polymerelektrolyt- und Direkt-Methanol-Brennstoffzellen verdeutlichen sowohl den Einfluss von Betriebsbedingungen als auch die Auswirkung von Materialeigenschaften auf die Ausbildung zweiphasiger Stroemungen.

  5. How does the Mass Transport in Disk Galaxy Models Influence the Character of Orbits?

    Directory of Open Access Journals (Sweden)

    Zotos Euaggelos E.

    2014-12-01

    Full Text Available We explore the regular or chaotic nature of orbits of stars moving in the meridional (R, z plane of an axially symmetric time-dependent disk galaxy model with a central, spherically symmetric nucleus. In particular, mass is linearly transported from the disk to the galactic nucleus, in order to mimic, in a way, the case of self-consistent interactions of an actual N-body simulation. We thus try to unveil the influence of this mass transportation on the different families of orbits of stars by monitoring how the percentage of chaotic orbits, as well as the percentages of orbits of the main regular resonant families, evolve as the galaxy develops a dense and massive nucleus in its core. The SALI method is applied to samples of orbits in order to distinguish safely between ordered and chaotic motion. In addition, a method based on the concept of spectral dynamics is used for identifying the various families of regular orbits and also for recognizing the secondary resonances that bifurcate from them. Our computations strongly suggest that the amount of the observed chaos is substantially increased as the nucleus becomes more massive. Furthermore, extensive numerical calculations indicate that there are orbits which change their nature from regular to chaotic and vice versa and also orbits which maintain their orbital character during the galactic evolution. The present outcomes are compared to earlier related work.

  6. A two-dimensional, two-phase mass transport model for liquid-feed DMFCs

    International Nuclear Information System (INIS)

    Yang, W.W.; Zhao, T.S.

    2007-01-01

    A two-dimensional, isothermal two-phase mass transport model for a liquid-feed direct methanol fuel cell (DMFC) is presented in this paper. The two-phase mass transport in the anode and cathode porous regions is formulated based on the classical multiphase flow in porous media without invoking the assumption of constant gas pressure in the unsaturated porous medium flow theory. The two-phase flow behavior in the anode flow channel is modeled by utilizing the drift-flux model, while in the cathode flow channel the homogeneous mist-flow model is used. In addition, a micro-agglomerate model is developed for the cathode catalyst layer. The model also accounts for the effects of both methanol and water crossover through the membrane. The comprehensive model formed by integrating those in the different regions is solved numerically using a home-written computer code and validated against the experimental data in the literature. The model is then used to investigate the effects of various operating and structural parameters, such as methanol concentration, anode flow rate, porosities of both anode and cathode electrodes, the rate of methanol crossover, and the agglomerate size, on cell performance

  7. Mass transport enhancement in redox flow batteries with corrugated fluidic networks

    Science.gov (United States)

    Lisboa, Kleber Marques; Marschewski, Julian; Ebejer, Neil; Ruch, Patrick; Cotta, Renato Machado; Michel, Bruno; Poulikakos, Dimos

    2017-08-01

    We propose a facile, novel concept of mass transfer enhancement in flow batteries based on electrolyte guidance in rationally designed corrugated channel systems. The proposed fluidic networks employ periodic throttling of the flow to optimally deflect the electrolytes into the porous electrode, targeting enhancement of the electrolyte-electrode interaction. Theoretical analysis is conducted with channels in the form of trapezoidal waves, confirming and detailing the mass transport enhancement mechanism. In dilute concentration experiments with an alkaline quinone redox chemistry, a scaling of the limiting current with Re0.74 is identified, which compares favourably against the Re0.33 scaling typical of diffusion-limited laminar processes. Experimental IR-corrected polarization curves are presented for high concentration conditions, and a significant performance improvement is observed with the narrowing of the nozzles. The adverse effects of periodic throttling on the pumping power are compared with the benefits in terms of power density, and an improvement of up to 102% in net power density is obtained in comparison with the flow-by case employing straight parallel channels. The proposed novel concept of corrugated fluidic networks comes with facile fabrication and contributes to the improvement of the transport characteristics and overall performance of redox flow battery systems.

  8. Effect of mass and charge transport speed and direction in porous anodes on microbial electrolysis cell performance

    NARCIS (Netherlands)

    Sleutels, T.H.J.A.; Hamelers, H.V.M.; Buisman, C.J.N.

    2011-01-01

    The use of porous electrodes like graphite felt as anode material has the potential of achieving high volumetric current densities. High volumetric current densities, however, may also lead to mass transport limitations within these porous materials. Therefore, in this study we investigated the mass

  9. USING MOLECULAR PROBES TO STUDY INTERFACIAL REDOX REACTION AT FE-BEARING SMECTITES

    Science.gov (United States)

    The interfacial electron transfer of clay-water systems has a wide range of significance in geochemical and biogeochernical environments. However the mechanism of interfacial electron transport is poorly understood. The electron transfer mechanism at the solid-water interfaces of...

  10. Electrical transport, electrothermal transport, and effective electron mass in single-crystalline In2O3 films

    Science.gov (United States)

    Preissler, Natalie; Bierwagen, Oliver; Ramu, Ashok T.; Speck, James S.

    2013-08-01

    A comprehensive study of the room-temperature electrical and electrothermal transport of single-crystalline indium oxide (In2O3) and indium tin oxide (ITO) films over a wide range of electron concentrations is reported. We measured the room-temperature Hall mobility μH and Seebeck coefficient S of unintentionally doped and Sn-doped high-quality, plasma-assisted molecular-beam-epitaxy-grown In2O3 for volume Hall electron concentrations nH from 7×1016 cm-3 (unintentionally doped) to 1×1021 cm-3 (highly Sn-doped, ITO). The resulting empirical S(nH) relation can be directly used in other In2O3 samples to estimate the volume electron concentration from simple Seebeck coefficient measurements. The mobility and Seebeck coefficient were modeled by a numerical solution of the Boltzmann transport equation. Ionized impurity scattering and polar optical phonon scattering were found to be the dominant scattering mechanisms. Acoustic phonon scattering was found to be negligible. Fitting the temperature-dependent mobility above room temperature of an In2O3 film with high mobility allowed us to find the effective Debye temperature (ΘD=700 K) and number of phonon modes (NOPML=1.33) that best describe the polar optical phonon scattering. The modeling also yielded the Hall scattering factor rH as a function of electron concentration, which is not negligible (rH≈1.4) at nondegenerate electron concentrations. Fitting the Hall-scattering-factor corrected concentration-dependent Seebeck coefficient S(n) for nondegenerate samples to the numerical solution of the Boltzmann transport equation and to widely used, simplified equations allowed us to extract an effective electron mass of m*=(0.30±0.03)me (with free electron mass me). The modeled mobility and Seebeck coefficient based on polar optical phonon and ionized impurity scattering describes the experimental results very accurately up to electron concentrations of 1019 cm-3, and qualitatively explains a mobility plateau or local

  11. Electroneutrality and ionic interactions in the modeling of mass transport in dilute electrochemical systems

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Swarnavo, E-mail: ss927@cornell.edu [School of Civil and Environmental Engineering, Cornell University, Ithaca, NY 14850 (United States); Aquino, Wilkins, E-mail: wa27@cornell.edu [School of Civil and Environmental Engineering, Cornell University, Ithaca, NY 14850 (United States)

    2011-10-01

    Highlights: > A simple ionic transport model including Coulombic interactions is proposed. > A connection between electroneutrality and Onsager's cross-flux terms is established. > Interionic flux densities are obtained from a constrained variational statement. > The numerical stiffness of the classical P-N-P system is bypassed using our proposed approach. - Abstract: We propose a simple, but novel mathematical and numerical approach to describe mass transport in dilute solutions, taking into consideration ionic interactions. Our proposed approach treats fluxes due to ionic interactions as additional unknowns in the transport equation. Through variational arguments, we derive a simple expression for these ionic fluxes in terms of the electroneutrality condition, which allows for a straightforward treatment of the new unknowns. Furthermore, a finite element formulation based on our mathematical model is presented. Finally, using the distribution of the interionic flux density and an energy dissipation function, we show that besides properly capturing flow due to ionic interactions, our model can also describe independent ionic flow as predicted by the conventional Nernst-Planck equation in regions where ionic interactions are weak.

  12. A heuristic simulation model of Lake Ontario circulation and mass balance transport

    Science.gov (United States)

    McKenna, J.E.; Chalupnicki, M.A.

    2011-01-01

    The redistribution of suspended organisms and materials by large-scale currents is part of natural ecological processes in large aquatic systems but can contribute to ecosystem disruption when exotic elements are introduced into the system. Toxic compounds and planktonic organisms spend various lengths of time in suspension before settling to the bottom or otherwise being removed. We constructed a simple physical simulation model, including the influence of major tributaries, to qualitatively examine circulation patterns in Lake Ontario. We used a simple mass balance approach to estimate the relative water input to and export from each of 10 depth regime-specific compartments (nearshore vs. offshore) comprising Lake Ontario. Despite its simplicity, our model produced circulation patterns similar to those reported by more complex studies in the literature. A three-gyre pattern, with the classic large counterclockwise central lake circulation, and a simpler two-gyre system were both observed. These qualitative simulations indicate little offshore transport along the south shore, except near the mouths of the Niagara River and Oswego River. Complex flow structure was evident, particularly near the Niagara River mouth and in offshore waters of the eastern basin. Average Lake Ontario residence time is 8 years, but the fastest model pathway indicated potential transport of plankton through the lake in as little as 60 days. This simulation illustrates potential invasion pathways and provides rough estimates of planktonic larval dispersal or chemical transport among nearshore and offshore areas of Lake Ontario. ?? 2011 Taylor & Francis.

  13. Solvent-Induced Crystallization in Poly(Ethylene Terephthalate) during Mass Transport

    Science.gov (United States)

    Ouyang, Hao

    2001-03-01

    The solvent transport in poly(ethylene terephthalate) (PET) and related phase transformation were investigated. The data of mass sorption were analyzed according to Harmon¡¦s model for Case I (Fickian), Case II (swelling) and anomalous transport. This transport process in PET is accompanied by the induced crystallization of the original amorphous state. The transformation was studied by wide angle x-ray scattering (WAXS), small angle x-ray scattering (SAXS), Differential Scanning Calorimeter (DSC), density gradient column, and Fourier Transform Infra-Red (FTIR). During this process, the matrix is under a compressive strain that causes different kinetic path of crystallization as compared to that by thermal annealing. This state of strain will assist the development of the solvent-induced crystallization. It also can be explained in terms of the principle of Le Chatelier if the local equilibrium is assumed. The model regarding the crystallization was proposed in terms of the study of long period L, the crystal thickness lc and the thickness of amorphous layer la, obtained from the linear correlation function and interface distribution function.

  14. Microbial air quality in mass transport buses and work-related illness among bus drivers of Bangkok Mass Transit Authority.

    Science.gov (United States)

    Luksamijarulkul, Pipat; Sundhiyodhin, Viboonsri; Luksamijarulkul, Soavalug; Kaewboonchoo, Orawan

    2004-06-01

    The air quality in mass transport buses, especially air-conditioned buses may affect bus drivers who work full time. Bus numbers 16, 63, 67 and 166 of the Seventh Bus Zone of Bangkok Mass Transit Authority were randomly selected to investigate for microbial air quality. Nine air-conditioned buses and 2-4 open-air buses for each number of the bus (36 air-conditioned buses and 12 open-air buses) were included. Five points of in-bus air samples in each studied bus were collected by using the Millipore A ir Tester Totally, 180 and 60 air samples collected from air-conditioned buses and open-air buses were cultured for bacterial and fungal counts. The bus drivers who drove the studied buses were interviewed towards histories of work-related illness while working. The results revealed that the mean +/- SD of bacterial counts in the studied open-air buses ranged from 358.50 +/- 146.66 CFU/m3 to 506 +/- 137.62 CFU/m3; bus number 16 had the highest level. As well as the mean +/- SD of fungal counts which ranged from 93.33 +/- 44.83 CFU/m3 to 302 +/- 294.65 CFU/m3; bus number 166 had the highest level. Whereas, the mean +/- SD of bacterial counts in the studied air-conditioned buses ranged from 115.24 +/- 136.01 CFU/m3 to 244.69 +/- 234.85 CFU/m3; bus numbers 16 and 67 had the highest level. As well as the mean +/- SD of fungal counts which rangedfrom 18.84 +/- 39.42 CFU/m3 to 96.13 +/- 234.76 CFU/m3; bus number 166 had the highest level. When 180 and 60 studied air samples were analyzed in detail, it was found that 33.33% of the air samples from open-air buses and 6.11% of air samples from air-conditioned buses had a high level of bacterial counts (> 500 CFU/m3) while 6.67% of air samples from open-air buses and 2.78% of air samples from air-conditioned buses had a high level of fungal counts (> 500 CFU/m3). Data from the history of work-related illnesses among the studied bus drivers showed that 91.67% of open-air bus drivers and 57.28% of air-conditioned bus drivers had

  15. Interfacial thermal conductance in multilayer graphene/phosphorene heterostructure

    International Nuclear Information System (INIS)

    Zhang, Ying-Yan; Pei, Qing-Xiang; Mai, Yiu-Wing; Lai, Siu-Kai

    2016-01-01

    Vertical integration of 2D materials has recently appeared as an effective method for the design of novel nano-scale devices. Using non-equilibrium molecular dynamics simulations, we study the interfacial thermal transport property of graphene/phosphorene heterostructures where phosphorene is sandwiched in between graphene. Various modulation techniques are thoroughly explored. We found that the interfacial thermal conductance at the interface of graphene and phosphorene can be enhanced significantly by using vacancy defects, hydrogenation and cross-plane compressive strain. By contrast, the reduction in the interfacial thermal conductance can be achieved by using cross-plane tensile strain. Our results provide important guidelines for manipulating the thermal transport in graphene/phosphorene based-nano-devices. (paper)

  16. Arabian Night and Sea Story - Biomarkers from a Giant Mass Transport Deposit.

    Science.gov (United States)

    Bratenkov, Sophia; Kulhanek, Denise K.; Clift, Peter D.; George, Simon C.

    2016-04-01

    The study of mass transport deposits (MTDs) is an important field of research due to the potential insights into catastrophic events in the past and modern geohazard threats (e.g. tsunamis). Submarine mass movements are very significant processes in sculpturing the structure of continental margins, particularly in their extent and magnitude that have consequences both in the modern day, as well as in the geological past. An understanding of the complex stratigraphy of a submarine mass transport deposit (MTD) might help in reconstructing the provenance and transport pathways of sedimentary material and thus give important insights into sedimentary dynamics and processes triggering specific events. Drilling operations during International Ocean Discovery Program (IODP) Expedition 355 Arabian Sea Monsoon, which took place during April and May, 2015 cored two sites in Laxmi Basin. Site U1456 was cored to 1109.4 m below seafloor (mbsf), with the oldest recovered rock dated to ~13.5-17.7 Ma. Site U1457 was cored to 1108.6 mbsf, with the oldest rock dated to ~62 Ma. At each site, we cored through ~330 m and ~190 m of MTD material. The MTD layers mainly consist of interbedded lithologies of dark grey claystone, light greenish calcarenite and calcilutite, and conglomerate/breccia, with ages based on calcareous nannofossil and foraminifer biostratigraphy ranging from the Eocene to early Miocene (Pandey et al., 2015). This MTD, known as Nataraja Slide, is the third largest MTD known from the geological record and the second largest on a passive margin. Calvés et al. (2015) identified a potential source area offshore Sourashstra on the Indian continental margin and invoked the single step mass movement model to explain the mechanism of emplacement. Initial shipboard work demonstrated the high variability in total organic carbon and total nitrogen levels in different layers within the MTD, which raises a number of questions related to the source and composition of the organic

  17. Monthly Variation of Taiwan Strait Through-flow Transports and Associated Water Masses

    Science.gov (United States)

    Jan, S.; Sheu, D.; Kuo, H.

    2005-05-01

    Through-flow transports and associated water masses are analyzed using current data measured by bottom-mounted and ship-board ADCP (1999-2001) across the central Taiwan Strait and strait-wide hydrographic data acquired from 79 CTD survey cruises (1986-2003). The East Asian monsoon, from southwest in July to August and northeast in October to March, controls the transport fluctuation which peaks in August (2.34 Sv northward), is hampered by the northeast monsoon after September and diminishes to the minimum (0.26 Sv southward) in December. The standard deviation of the calculated transport ranges from 0.56 to 1.05 Sv during northeast monsoon months and is relatively small in other months. A cluster analysis together with conventional T-S diagrams identifies the saline and warm Kuroshio Branch Water (KBW), the less saline South China Sea Surface Water (SCSSW), the brackish and cold China Coastal Water (CCW), the saline Subsurface Water (SW) (depth > 100 m) and the Diluted Coastal Water (DCW). The majority of the northward transport in summer carries the SCSSW to the East China Sea. Meanwhile, the DCW appears off the northwest bank of the strait and the SW resides in the bottom layer of a deep trench in the southeastern strait. The onset of the northeast monsoon in September drives the CCW from the Yangtze river mouth to the northern strait. In the southern strait, the northward-moving KBW replaces the SCSSW and meets the southward-intruding CCW in the middle strait during November to April.

  18. Interfacial forces in aqueous media

    CERN Document Server

    van Oss, Carel J

    2006-01-01

    Thoroughly revised and reorganized, the second edition of Interfacial Forces in Aqueous Media examines the role of polar interfacial and noncovalent interactions among biological and nonbiological macromolecules as well as biopolymers, particles, surfaces, cells, and both polar and apolar polymers. The book encompasses Lifshitz-van der Waals and electrical double layer interactions, as well as Lewis acid-base interactions between colloidal entities in polar liquids such as water. New in this Edition: Four previously unpublished chapters comprising a new section on interfacial propertie

  19. Interfacial Instabilities in Evaporating Drops

    Science.gov (United States)

    Moffat, Ross; Sefiane, Khellil; Matar, Omar

    2007-11-01

    We study the effect of substrate thermal properties on the evaporation of sessile drops of various liquids. An infra-red imaging technique was used to record the interfacial temperature. This technique illustrates the non-uniformity in interfacial temperature distribution that characterises the evaporation process. Our results also demonstrate that the evaporation of methanol droplets is accompanied by the formation of wave-trains in the interfacial temperature field; similar patterns, however, were not observed in the case of water droplets. More complex patterns are observed for FC-72 refrigerant drops. The effect of substrate thermal conductivity on the structure of the complex pattern formation is also elucidated.

  20. Effect of interfacial turbulence and accommodation coefficient on CFD predictions of pressurization and pressure control in cryogenic storage tank

    Science.gov (United States)

    Kassemi, Mohammad; Kartuzova, Olga

    2016-03-01

    Pressurization and pressure control in cryogenic storage tanks are to a large extent affected by heat and mass transport across the liquid-vapor interface. These mechanisms are, in turn, controlled by the kinetics of the phase change process and the dynamics of the turbulent recirculating flows in the liquid and vapor phases. In this paper, the effects of accommodation coefficient and interfacial turbulence on tank pressurization and pressure control simulations are examined. Comparison between numerical predictions and ground-based measurements in two large liquid hydrogen tank experiments, performed in the K-site facility at NASA Glenn Research Center (GRC) and the Multi-purpose Hydrogen Test Bed (MHTB) facility at NASA Marshall Space Flight Center (MSFC), are used to show the impact of accommodation coefficient and interfacial and vapor phase turbulence on evolution of pressure and temperatures in the cryogenic storage tanks. In particular, the self-pressurization comparisons indicate that: (1) numerical predictions are essentially independent of the magnitude of the accommodation coefficient; and (2) surprisingly, laminar models sometimes provide results that are in better agreement with experimental self-pressurization rates, even in parametric ranges where the bulk flow is deemed fully turbulent. In this light, shortcomings of the present CFD models, especially, numerical treatments of interfacial mass transfer and turbulence, as coupled to the Volume-of-Fluid (VOF) interface capturing scheme, are underscored and discussed.

  1. Porous media fluid flow, heat, and mass transport model with rock stress coupling

    International Nuclear Information System (INIS)

    Runchal, A.K.

    1980-01-01

    This paper describes the physical and mathematical basis of a general purpose porous media flow model, GWTHERM. The mathematical basis of the model is obtained from the coupled set of the classical governing equations for the mass, momentum and energy balance. These equations are embodied in a computational model which is then coupled externally to a linearly elastic rock-stress model. This coupling is rather exploratory and based upon empirical correlations. The coupled model is able to take account of time-dependent, inhomogeneous and anisotropic features of the hydrogeologic, thermal and transport phenomena. A number of applications of the model have been made. Illustrations from the application of the model to nuclear waste repositories are included

  2. Mass transport aspects of polymer electrolyte fuel cells under two-phase flow conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, D.

    2007-03-15

    This well-illustrated, comprehensive dissertation by Dr. Ing. Denis Kramer takes an in-depth look at polymer electrolyte fuel cells (PEFC) and the possibilities for their application. First of all, the operating principles of polymer electrolyte fuel cells are described and discussed, whereby thermodynamics aspects and loss mechanisms are examined. The mass transport diagnostics made with respect to the function of the cells are discussed. Field flow geometry, gas diffusion layers and, amongst other things, liquid distribution, the influence of flow direction and the low-frequency behaviour of air-fed PEFCs are discussed. Direct methanol fuel cells are examined, as are the materials chosen. The documentation includes comprehensive mathematical and graphical representations of the mechanisms involved.

  3. The role of mass transport pathway in wormholelike mesoporous carbon for supercapacitors.

    Science.gov (United States)

    Liang, Yeru; Liang, Fengxue; Li, Zhenghui; Wu, Dingcai; Yan, Fangyu; Li, Siyu; Fu, Ruowen

    2010-09-28

    In the present paper, we demonstrate the importance of the role of a mass transport pathway (MTP) in wormholelike mesoporous carbon (WMC) through studying the ion diffusion behaviors within two different wormholelike mesopore networks with and without MTP. Our results reveal that the introduction of MTP is very helpful in improving ion diffusion properties. The as-prepared WMC with a MTP of ca. 9.7 nm exhibits notably better electric double layer performance as compared to the conventional WMC without a MTP. For example, even at the quick sweep rate of 50 mV s(-1), the surface specific capacitance of the former is 21.6 microF cm(-2), which is almost 4 times as high as that of the latter (5.5 microF cm(-2)).

  4. Influence of mass transport towards deactivation in tert-butyl-source driven isobutane/2-butene alkylation

    Energy Technology Data Exchange (ETDEWEB)

    Aschauer, S.J.; Jess, A. [Bayreuth Univ. (Germany). Dept. of Chemical Engineering

    2011-07-01

    The deactivation of i-butane/trans-2-butene alkylation using tert-butyl-halide promoted ionic liquid catalysts is studied.Here, the mass transport was modified by varying the feed rate and the type of promoter addition. The experimental data show that the deactivation increases with increasing feed rate. Moreover, a biliquid foam is formed when feed rates above 1 g/min are adjusted. As the results indicate a strong influence of the biliquid foam and its formation on deactivation, both aspects are also discussed.When the promoter is added to the feed mixture an increase of conversion with time on stream is observed. A deactivation in continuous promoter addition mode could not be noted in the investigated time-on-stream range. (orig.)

  5. Comparison of one-, two-, and three-dimensional models for mass transport of radionuclides

    International Nuclear Information System (INIS)

    Prickett, T.A.; Voorhees, M.L.; Herzog, B.L.

    1980-02-01

    This technical memorandum compares one-, two-, and three-dimensional models for studying regional mass transport of radionuclides in groundwater associated with deep repository disposal of high-level radioactive wastes. In addition, this report outlines the general conditions for which a one- or two-dimensional model could be used as an alternate to a three-dimensional model analysis. The investigation includes a review of analytical and numerical models in addition to consideration of such conditions as rock and fluid heterogeneity, anisotropy, boundary and initial conditions, and various geometric shapes of repository sources and sinks. Based upon current hydrologic practice, each review is taken separately and discussed to the extent that the researcher can match his problem conditions with the minimum number of model dimensions necessary for an accurate solution

  6. The Sheath Transport Observer for the Redistribution of Mass (STORM) Image

    Science.gov (United States)

    Kuntz, Kip; Collier, Michael; Sibeck, David G.; Porter, F. Scott; Carter, J. A.; Cravens, Thomas; Omidi, N.; Robertson, Ina; Sembay, S.; Snowden, Steven L.

    2008-01-01

    All of the solar wind energy that powers magnetospheric processes passes through the magnetosheath and magnetopause. Global images of the magnetosheath and magnetopause boundary layers will resolve longstanding controversy surrounding fundamental phenomena that occur at the magnetopause and provide information needed to improve operational space weather models. Recent developments showing that soft X-rays (0.15-1 keV) result from high charge state solar wind ions undergoing charge exchange recombination through collisions with exospheric neutral atoms has led to the realization that soft X-ray imaging can provide global maps of the high-density shocked solar wind within the magnetosheath and cusps, regions lying between the lower density solar wind and magnetosphere. We discuss an instrument concept called the Sheath Transport Observer for the Redistribution of Mass (STORM), an X-ray imager suitable for simultaneously imaging the dayside magnetosheath, the magnetopause boundary layers, and the cusps.

  7. The Sheath Transport Observer for the Redistribution of Mass (STORM) Imager

    Science.gov (United States)

    Collier, Michael R.; Sibeck, David G.; Porter, F. Scott; Burch, J.; Carter, J. A.; Cravens, Thomas; Kuntz, Kip; Omidi, N.; Read, A.; Robertson, Ina; hide

    2010-01-01

    All of the solar wind energy that powers magnetospheric processes passes through the magnetosheath and magnetopause. Global images of the magnetosheath and magnetopause boundary layers will resolve longstanding controversies surrounding fundamental phenomena that occur at the magnetopause and provide information needed to improve operational space weather models. Recent developments showing that soft X-rays (0.15-1 keV) result from high charge state solar wind ions undergoing charge exchange recombination through collisions with exospheric neutral atoms has led to the realization that soft X-ray imaging can provide global maps of the high-density shocked solar wind within the magnetosheath and cusps, regions lying between the lower density solar wind and magnetosphere. We discuss an instrument concept called the Sheath Transport Observer for the Redistribution of Mass (STORM), an X-ray imager suitable for simultaneously imaging the dayside magnetosheath, the magnetopause boundary layers, and the cusps.

  8. Architecture for improved mass transport and system performance in redox flow batteries

    Science.gov (United States)

    Houser, Jacob; Pezeshki, Alan; Clement, Jason T.; Aaron, Douglas; Mench, Matthew M.

    2017-05-01

    In this work, electrochemical performance and parasitic losses are combined in an overall system-level efficiency metric for a high performance, all-vanadium redox flow battery. It was found that pressure drop and parasitic pumping losses are relatively negligible for high performance cells, i.e., those capable of operating at a high current density while at a low flow rate. Through this finding, the Equal Path Length (EPL) flow field architecture was proposed and evaluated. This design has superior mass transport characteristics in comparison with the standard serpentine and interdigitated designs at the expense of increased pressure drop. An Aspect Ratio (AR) design is discussed and evaluated, which demonstrates decreased pressure drop compared to the EPL design, while maintaining similar electrochemical performance under most conditions. This AR design is capable of leading to improved system energy efficiency for flow batteries of all chemistries.

  9. Optimal-mass-transfer-based estimation of glymphatic transport in living brain

    Science.gov (United States)

    Ratner, Vadim; Zhu, Liangjia; Kolesov, Ivan; Nedergaard, Maiken; Benveniste, Helene; Tannenbaum, Allen

    2015-03-01

    It was recently shown that the brain-wide cerebrospinal fluid (CSF) and interstitial fluid exchange system designated the `glymphatic pathway' plays a key role in removing waste products from the brain, similarly to the lymphatic system in other body organs . It is therefore important to study the flow patterns of glymphatic transport through the live brain in order to better understand its functionality in normal and pathological states. Unlike blood, the CSF does not flow rapidly through a network of dedicated vessels, but rather through para-vascular channels and brain parenchyma in a slower time-domain, and thus conventional fMRI or other blood-flow sensitive MRI sequences do not provide much useful information about the desired flow patterns. We have accordingly analyzed a series of MRI images, taken at different times, of the brain of a live rat, which was injected with a paramagnetic tracer into the CSF via the lumbar intrathecal space of the spine. Our goal is twofold: (a) find glymphatic (tracer) flow directions in the live rodent brain; and (b) provide a model of a (healthy) brain that will allow the prediction of tracer concentrations given initial conditions. We model the liquid flow through the brain by the diffusion equation. We then use the Optimal Mass Transfer (OMT) approach to derive the glymphatic flow vector field, and estimate the diffusion tensors by analyzing the (changes in the) flow. Simulations show that the resulting model successfully reproduces the dominant features of the experimental data. Keywords: inverse problem, optimal mass transport, diffusion equation, cerebrospinal fluid flow in brain, optical flow, liquid flow modeling, Monge Kantorovich problem, diffusion tensor estimation

  10. Three-Dimensional Network Model for Coupling of Fracture and Mass Transport in Quasi-Brittle Geomaterials

    Directory of Open Access Journals (Sweden)

    Peter Grassl

    2016-09-01

    Full Text Available Dual three-dimensional networks of structural and transport elements were combined to model the effect of fracture on mass transport in quasi-brittle geomaterials. Element connectivity of the structural network, representing elasticity and fracture, was defined by the Delaunay tessellation of a random set of points. The connectivity of transport elements within the transport network was defined by the Voronoi tessellation of the same set of points. A new discretisation strategy for domain boundaries was developed to apply boundary conditions for the coupled analyses. The properties of transport elements were chosen to evolve with the crack opening values of neighbouring structural elements. Through benchmark comparisons involving non-stationary transport and fracture, the proposed dual network approach was shown to be objective with respect to element size and orientation.

  11. Interfacial effects in organic semiconductor heterojunctions

    International Nuclear Information System (INIS)

    Stadler, P.

    2011-01-01

    The field of organic electronics has systematically gained interest in recent years, technologically and scientifically advances have been made leading to practical applications such as organic light emitting diodes, organic field-effect transistors and organic photo-voltaic cells. In this thesis a fundamental study on organic molecules is presented targeting on interfacial effects at organic heterojunctions. Generally in organic electronic devices interfaces are considered as key parameters for achieving high performance applications. Therefore in this work the emphasis is to investigate layer-by-layer heterojunctions of organic molecules. Defined heterojunctions at inorganic III-V semiconductors form superlattices and quantum-wells, which lead to interfacial effects summarized as quantum confinement and two-dimensional electron gases. Although organic molecules differ in many aspects from their inorganic counterparts, similar effects can be theoretically expected at organic heterojunctions as well. Organic molecules form van-der-Waals type crystals and domains which are macroscopically anisotropic and polycrystalline or amorphous. Organic molecules are intrinsic semiconductors and at interfaces dipoles are formed, which control the energy level alignment. In order to characterize such structures and compare them to inorganic superlattices and quantum-wells it is necessary to induce charge carriers. In this work this is established either by interfacial doping using high-performance dielectrics in a field-effect transistor structure or by photo-doping by exciting a donor-acceptor bilayer. In both cases C 60 was chosen as organic semiconductor exhibiting good acceptor properties and an electron mobility in the range of 0.5 cm 2 V -1 s -1 . The fabrication of well-defined few-molecular layers allows probing directly at the interface. Spectroscopic methods and transport measurements are applied for characterization: Photoemission spectroscopy, absorption and photo

  12. Mass transport around comets and its impact on the seasonal differences in water production rates

    Energy Technology Data Exchange (ETDEWEB)

    Rubin, M.; Altwegg, K.; Thomas, N. [Physikalisches Institut, University of Bern, Sidlerstrasse 5, 3012 Bern (Switzerland); Fougere, N.; Combi, M. R.; Tenishev, V. M. [Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109 (United States); Le Roy, L. [Center for Space and Habitability, University of Bern, Sidlerstrasse 5, 3012 Bern (Switzerland)

    2014-06-20

    Comets are surrounded by a thin expanding atmosphere, and although the nucleus' gravity is small, some molecules and grains, possibly with the inclusion of ices, can get transported around the nucleus through scattering (atoms/molecules) and gravitational pull (grains). Based on the obliquity of the comet, it is also possible that volatile material and icy grains get trapped in regions, which are in shadow until the comet passes its equinox. When the Sun rises above the horizon and the surface starts to heat up, this condensed material starts to desorb and icy grains will sublimate off the surface, possibly increasing the comet's neutral gas production rate on the outbound path. In this paper we investigate the mass transport around the nucleus, and based on a simplified model, we derive the possible contribution to the asymmetry in the seasonal gas production rate that could arise from trapped material released from cold areas once they come into sunlight. We conclude that the total amount of volatiles retained by this effect can only contribute up to a few percent of the asymmetry observed in some comets.

  13. Plasma viscosity with mass transport in spherical inertial confinement fusion implosion simulations

    Energy Technology Data Exchange (ETDEWEB)

    Vold, E. L.; Molvig, K. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Joglekar, A. S. [University of Michigan, Ann Arbor, Michigan 48109 (United States); Ortega, M. I. [University of New Mexico, Albuquerque, New Mexico 87131 (United States); Moll, R. [University of California, Santa Cruz, California 95064 (United States); Fenn, D. [Florida State University, Tallahassee, Florida 32306 (United States)

    2015-11-15

    The effects of viscosity and small-scale atomic-level mixing on plasmas in inertial confinement fusion (ICF) currently represent challenges in ICF research. Many current ICF hydrodynamic codes ignore the effects of viscosity though recent research indicates viscosity and mixing by classical transport processes may have a substantial impact on implosion dynamics. We have implemented a Lagrangian hydrodynamic code in one-dimensional spherical geometry with plasma viscosity and mass transport and including a three temperature model for ions, electrons, and radiation treated in a gray radiation diffusion approximation. The code is used to study ICF implosion differences with and without plasma viscosity and to determine the impacts of viscosity on temperature histories and neutron yield. It was found that plasma viscosity has substantial impacts on ICF shock dynamics characterized by shock burn timing, maximum burn temperatures, convergence ratio, and time history of neutron production rates. Plasma viscosity reduces the need for artificial viscosity to maintain numerical stability in the Lagrangian formulation and also modifies the flux-limiting needed for electron thermal conduction.

  14. A thermodynamic/mass-transport model for the release of ruthenium from irradiated fuel

    International Nuclear Information System (INIS)

    Garisto, F.; Iglesias, F.C.; Hunt, C.E.L.

    1990-01-01

    Some postulated nuclear reactor accidents lead to fuel failures and hence release of fission products into the primary heat transport system (PHTS). To determine the consequences of such accidents, it is important to understand the behavior of fission products both in the PHTS and in the reactor containment building. Ruthenium metal has a high boiling point and is nonvolatile under reducing conditions. However, under oxidizing conditions ruthenium can form volatile oxides at relatively low temperatures and, hence, could escape from failed fuel and enter the containment building. The ruthenium radioisotope Ru-106 presents a potentially significant health risk if it is released outside the reactor containment building. Consequently, it is important to understand the behavior of ruthenium during a nuclear reactor accident. The authors review the thermodynamic behavior of ruthenium at high temperatures. The qualitative behavior of ruthenium, predicted using thermodynamic calculations, is then compared with experimental results from the Chalk River Nuclear Laboratories (CRNL). Finally, a simple thermodynamic/mass-transport model is proposed to explain the release behavior of ruthenium in a steam atmosphere

  15. Anisotropy effect of the clay soil masses on the stress-strain state of transport tunnels

    Directory of Open Access Journals (Sweden)

    Yushkov Boris Semenovich

    2014-09-01

    Full Text Available The article considers the kinds of clay soil mass anisotropy in the form of the spatial heterogeneity of properties of thawed and frozen soils, ambiguity of the frost heaving values and shrinkage in different directions. The questions of anisotropy of the clay soil properties at the positive temperatures are reported. The dependence of the heterogeneity of the physical and mechanical properties of frozen soils from the cryogenic texture, natural arrangement, different types of stratification and interbedding is considered. Indexes of the strength and strain anisotropy are noted. The accounting possibilities of the basic numerical indexes of heaving phenomena from the standpoint of anisotropy of the properties and processes inherent in the freezing through soil are analyzed by substitution in the heaving strain formula. The unevenness of thawed soil shrinkage in vertical and horizontal directions is noted during the freezing of the top layer. The unevenness of shrinkage in different directions is connected with kind of stress and cryogenic texture. Anisotropy of the frost heaving process is considered in the context of one-dimensional and non-one-dimensional problem depending on the amount of the freezing fronts and their direction. There is summarized the effect of anisotropy appearances on the stress-strain state of the transport tunnel. One can conclude that the resulting non-uniformity of heaving and shrinkage in conjunction with anisotropic properties of frozen soils, is a significant component in the complex of power factors determining the optimal design solution of a transport tunnel.

  16. Mass

    International Nuclear Information System (INIS)

    Quigg, Chris

    2007-01-01

    In the classical physics we inherited from Isaac Newton, mass does not arise, it simply is. The mass of a classical object is the sum of the masses of its parts. Albert Einstein showed that the mass of a body is a measure of its energy content, inviting us to consider the origins of mass. The protons we accelerate at Fermilab are prime examples of Einsteinian matter: nearly all of their mass arises from stored energy. Missing mass led to the discovery of the noble gases, and a new form of missing mass leads us to the notion of dark matter. Starting with a brief guided tour of the meanings of mass, the colloquium will explore the multiple origins of mass. We will see how far we have come toward understanding mass, and survey the issues that guide our research today.

  17. Dynamics and mass transport of solutal convection in a closed porous media system

    Science.gov (United States)

    Wen, Baole; Akhbari, Daria; Hesse, Marc

    2016-11-01

    Most of the recent studies of CO2 sequestration are performed in open systems where the constant partial pressure of CO2 in the vapor phase results in a time-invariant saturated concentration of CO2 in the brine (Cs). However, in some closed natural CO2 reservoirs, e.g., Bravo Dome in New Mexico, the continuous dissolution of CO2 leads to a pressure drop in the gas that is accompanied by a reduction of Cs and thereby affects the dynamics and mass transport of convection in the brine. In this talk, I discuss the characteristics of convective CO2 dissolution in a closed system. The gas is assumed to be ideal and its solubility given by Henry's law. An analytical solution shows that the diffusive base state is no longer self-similar and that diffusive mass transfer declines rapidly. Scaling analysis reveals that the volume ratio of brine and gas η determines the behavior of the system. DNS show that no constant flux regime exists for η > 0 nevertheless, the quantity F /Cs2 remains constant, where F is the dissolution flux. The onset time is only affected by η when the Rayleigh number Ra is small. In this case, the drop in Cs during the initial diffusive regime significantly reduces the effective Ra and therefore delays the onset.

  18. Mass transport of heavy metal ions and radon in gels used as sealing agents in containment technologies

    International Nuclear Information System (INIS)

    Lakatos, I.; Bauer, K.; Lakatos-Szabo, J.; Kretzschmar, H.J.

    1997-01-01

    The diffusion and hydrodynamic mass transport of multivalent cations, mostly Cr(III) and Cr(VI) ions and radon in polymer/silicate gels and Montanwax emulsions were studied. It was concluded that the self-conforming gels may decrease the hydrodynamic mass transport in porous and fractured media by 4-6 orders of magnitude. In water saturated systems, however, the diffusion transport can be restricted by hydrogels only to a moderate extent. On the other hand, the high and selective retention capacity of gels towards different diffusing species may open new vistas in the sealing technologies. Similar results were obtained for transport phenomena of radon. The almost perfect quenching process of radon and its nuclides in gels and emulsions further enhances the positive effects of the encapsulation methods. The laboratory experiments provided valuable new information to design the different containment technologies

  19. Mass transport of heavy metal ions and radon in gels used as sealing agents in containment technologies

    Energy Technology Data Exchange (ETDEWEB)

    Lakatos, I.; Bauer, K.; Lakatos-Szabo, J. [Research Lab. for Mining Chemistry, Miskolc-Egyetemvaros (Hungary); Kretzschmar, H.J. [DBI Gas- und Umwelttechnik GmbH, Feiberg (Germany)

    1997-12-31

    The diffusion and hydrodynamic mass transport of multivalent cations, mostly Cr(III) and Cr(VI) ions and radon in polymer/silicate gels and Montanwax emulsions were studied. It was concluded that the self-conforming gels may decrease the hydrodynamic mass transport in porous and fractured media by 4-6 orders of magnitude. In water saturated systems, however, the diffusion transport can be restricted by hydrogels only to a moderate extent. On the other hand, the high and selective retention capacity of gels towards different diffusing species may open new vistas in the sealing technologies. Similar results were obtained for transport phenomena of radon. The almost perfect quenching process of radon and its nuclides in gels and emulsions further enhances the positive effects of the encapsulation methods. The laboratory experiments provided valuable new information to design the different containment technologies.

  20. Green-Kubo relations for dynamic interfacial excess properties

    NARCIS (Netherlands)

    Sagis, L.M.C.

    2012-01-01

    In this paper we analyze the fluctuations of the in-plane interfacial excess fluxes in multiphase systems, in the context of the extended irreversible thermodynamics formalism. We derive expressions for the time correlation functions of the surface extra stress tensor, the surface mass flux vector,

  1. Drift effect and "negative" mass transport in an inhomogeneous medium: limiting case of a two-component lattice gas.

    Science.gov (United States)

    Lukyanets, Sergei P; Kliushnychenko, Oleksandr V

    2010-11-01

    The mass transport in an inhomogeneous medium is modeled as the limiting case of a two-component lattice gas with excluded volume constraint and one of the components fixed. In the long-wavelength approximation, the density relaxation of mobile particles is governed by diffusion and interaction with a medium inhomogeneity represented by the static component distribution. It is shown that the density relaxation can be locally accompanied by density distribution compression, i.e., the local mass transport directed from low-to high-density regions. The origin of such a "negative" mass transport is shown to be associated with the presence of a stationary drift flow defined by the medium inhomogeneity. In the quasi-one-dimensional case, the compression dynamics manifests itself in the hoppinglike motion of packet front position of diffusing substance due to staged passing through inhomogeneity barriers, and it leads to fragmentation of the packet and retardation of its spreading. The root-mean-square displacement reflects only the averaged packet front dynamics and becomes inappropriate as the transport characteristic in this regime. In the stationary case, the mass transport throughout the whole system may be directed from the boundary with lower concentration towards the boundary with higher concentration. Implications of the excluded volume constraint and particle distinguishability for these effects are discussed.

  2. Interfacial Friction and Adhesion of Polymer Brushes

    KAUST Repository

    Landherr, Lucas J. T.

    2011-08-02

    A bead-probe lateral force microscopy (LFM) technique is used to characterize the interfacial friction and adhesion properties of polymer brushes. Our measurements attempt to relate the physical structure and chemical characteristics of the brush to their properties as thin-film, tethered lubricants. Brushes are synthesized at several chain lengths and surface coverages from polymer chains of polydimethylsiloxane (PDMS), polystyrene (PS), and a poly(propylene glycol)-poly(ethylene glycol) block copolymer (PPG/PEG). At high surface coverage, PDMS brushes manifest friction coefficients (COFs) that are among the lowest recorded for a dry lubricant film (μ ≈ 0.0024) and close to 1 order of magnitude lower than the COF of a bare silicon surface. Brushes synthesized from higher molar mass chains exhibit higher friction forces than those created using lower molar mass polymers. Increased grafting density of chains in the brush significantly reduces the COF by creating a uniform surface of stretched chains with a decreased surface viscosity. Brushes with lower surface tension and interfacial shear stresses manifest the lowest COF. In particular, PDMS chains exhibit COFs lower than PS by a factor of 3.7 and lower than PPG/PEG by a factor of 4.7. A scaling analysis conducted on the surface coverage (δ) in relation to the fraction (ε) of the friction force developing from adhesion predicts a universal relation ε ∼ δ4/3, which is supported by our experimental data. © 2011 American Chemical Society.

  3. Using mass spectrometry for identification of ABC transporters from Xanthomonas citri and mutants expressed in different growth conditions

    International Nuclear Information System (INIS)

    Faria, J.N.; Balan, A.; Paes Leme, A.F.

    2012-01-01

    Full text: Xanthomonas citri is a phytopathogenic bacterium that infects citrus plants causing significant losses for the economy. In our group, we have focused on the identification and characterization of ABC transport proteins of this bacterium, in order to determinate their function for growth in vitro and in vivo, during infection. ABC transporters represent one of the largest families of proteins, which transport since small molecules as ions up to oligopeptides and sugars. In prokaryotic cells many works have reported the ABC transport function in pathogenesis, resistance, biofilm formation, infectivity and DNA repair, but until our knowledge, there is no data related to these transporters and X. citri. So, In order to determinate which transporters are expressed in X. citri, we started a proteomic analysis based on mono and bi-dimensional gels associated to mass spectrometry analyses. After growing X. citri and two different mutants deleted for ssuA and nitA genes in LB and minimum media, cellular extracts were obtained and used for preparation of mono and bi-dimensional gels. Seven bands covering the expected mass of ABC transporter components (20 kDa to 50 kDa) in SDS-PAGE were cut off the gel, treated with trypsin and submitted to the MS for protein identification. The results of 2D gels were good enough and will serve as a standard for development of similar experiments in large scale. (author)

  4. Interfacial Layer Engineering for Performance Enhancement in Polymer Solar Cells

    Directory of Open Access Journals (Sweden)

    Hao Zeng

    2015-02-01

    Full Text Available Improving power conversion efficiency and device performance stability is the most critical challenge in polymer solar cells for fulfilling their applications in industry at large scale. Various methodologies have been developed for realizing this goal, among them interfacial layer engineering has shown great success, which can optimize the electrical contacts between active layers and electrodes and lead to enhanced charge transport and collection. Interfacial layers also show profound impacts on light absorption and optical distribution of solar irradiation in the active layer and film morphology of the subsequently deposited active layer due to the accompanied surface energy change. Interfacial layer engineering enables the use of high work function metal electrodes without sacrificing device performance, which in combination with the favored kinetic barriers against water and oxygen penetration leads to polymer solar cells with enhanced performance stability. This review provides an overview of the recent progress of different types of interfacial layer materials, including polymers, small molecules, graphene oxides, fullerene derivatives, and metal oxides. Device performance enhancement of the resulting solar cells will be elucidated and the function and operation mechanism of the interfacial layers will be discussed.

  5. Carbonate Channel-Levee Systems Influenced by Mass-Transport Deposition, Browse Basin, Australia

    Science.gov (United States)

    Dunlap, D.; Janson, X.; Sanchez-Phelps, C.; Covault, J. A.

    2017-12-01

    Submarine channels are primary conduits for clastic sediment transport to deep-water basins, thereby controlling the location of marine depocenters and sediment bypass. The evolution and depositional character of submarine channels have broad implications to sediment dispersal, sediment quality, and hydrocarbon exploration potential. Siliciclastic channel systems have been extensively studied in modern environments, seismic and outcrop; however, carbonate channel-levee deposits have only recently been explored. Here we utilize newly released high-resolution (90 Hz) seismic-reflection data from the Australian Browse Basin to document the influence of mass-transport complex (MTC) deposition on the stratigraphic architecture of carbonate channel-levee systems. The 2014 vintage seismic survey is 2500 km2 and hosts numerous large Miocene-age carbonate channel-levee complexes basinward of the shelf edge. Regional horizons and individual channel forms were mapped. Channels range from 200-300 m wide and are bounded by high-relief levee-overbank wedges (>100 ms TWTT). These channels extend across the survey area >70 km. The leveed-channels were sourced from middle and late Miocene slope gullies linked to platform carbonates. Slope-attached and locally derived MTC's are evident throughout the Miocene section likely related to periods of basin inversion and shelf-edge gully incision. We interpret that regionally extensive (>1000 km2) slope-attached MTC's can shut down a channel-levee system and trigger the initiation of a new system, whereas more locally derived (wasting and turbidity currents, which informs depositional models of carbonate slope systems and calls for re-evaluation of the controls on stratigraphic patterns in mixed siliciclastic-carbonate deep-water basins.

  6. Subcontinuum mass transport of hydrocarbons in nanoporous media and long-time kinetics of recovery from unconventional reservoirs

    Science.gov (United States)

    Bocquet, Lyderic

    2015-11-01

    In this talk I will discuss the transport of hydrocarbons across nanoporous media and analyze how this transport impacts at larger scales the long-time kinetics of hydrocarbon recovery from unconventional reservoirs (the so-called shale gas). First I will establish, using molecular simulation and statistical mechanics, that the continuum description - the so-called Darcy law - fails to predict transport within a nanoscale organic matrix. The non-Darcy behavior arises from the strong adsorption of the alkanes in the nanoporous material and the breakdown of hydrodynamics at the nanoscale, which contradicts the assumption of viscous flow. Despite this complexity, all permeances collapse on a master curve with an unexpected dependence on alkane length, which can be described theoretically by a scaling law for the permeance. Then I will show that alkane recovery from such nanoporous reservoirs is dynamically retarded due to interfacial effects occuring at the material's interface. This occurs especially in the hydraulic fracking situation in which water is used to open fractures to reach the hydrocarbon reservoirs. Despite the pressure gradient used to trigger desorption, the alkanes remain trapped for long times until water desorbs from the external surface. The free energy barrier can be predicted in terms of an effective contact angle on the composite nanoporous surface. Using a statistical description of the alkane recovery, I will then demonstrate that this retarded dynamics leads to an overall slow - algebraic - decay of the hydrocarbon flux. Such a behavior is consistent with algebraic decays of shale gas flux from various wells reported in the literature. This work was performed in collaboration with B. Coasne, K. Falk, T. Lee, R. Pellenq and F. Ulm, at the UMI CNRS-MIT, Massachusetts Institute of Technology, Cambridge, USA.

  7. Mass-transport deposits and the advantages of a real three-dimensional perspective (Invited)

    Science.gov (United States)

    Moscardelli, L. G.; Wood, L. J.

    2010-12-01

    Mass-transport deposits (MTDs) form a significant component of the stratigraphic record in ancient and modern deepwater basins worldwide. However, the difficulties encountered when performing direct observations of these submarine units, the limited area covered by geophysical surveys acquired by research institutions, and the often surficial nature of seafloor data collected by federal agencies represent major hurdles in understanding submarine mass-movement dynamics. Three-dimensional seismic reflectivity imaging, drawn mainly from energy exploration in deepwater regions of the world, has allowed researchers to describe the architecture of MTDs at unprecedented spatial and temporal scales. In this talk, we present observations made using thousands of square kilometers of three-dimensional seismic data acquired by the oil and gas industry in offshore Trinidad, Morocco, and the Gulf of Mexico, where MTDs are a common occurrence in the stratigraphic record. Detailed mapping of MTD architecture has allowed us to better understand the role that MTDs have in continental-margin evolution. Morphometric data obtained from the mapping of MTDs is used to model tsunamigenic waves and their potential affect of coastal areas. The effect of low permeability MTDs on reservoir and aquifer fluid behavior has important implications, enhancing the economic importance of understanding the occurrence and distribution of these deposits. The recognition of MTD processes and morphology leads to new understanding of the processes possibly active in shaping other planets. Such analogs speak to a possible deepwater origin for features on Mars previously attributed to subaerial events. As industry-quality 3D seismic data become increasingly available to academic institutions, current studies become important bell weathers for future analysis of MTDs and processes in oceans of this planet and beyond.

  8. Coastal currents and mass transport of surface sediments over the shelf regions of Monterey Bay, California

    Science.gov (United States)

    Wolf, S.C.

    1970-01-01

    southward except near Monterey Canyon which acts as a physiographic barrier and the extreme southern end of the bay where currents are non persistent. Some sediments are also transported offshore by rip currents and other agencies and deposited in deeper, quieter waters. Supply of sediments to the canyon head results in over-filling and steepening with subsequent mass movement of sediments seaward followed by deposition in channels and on the broad deep sea fan. ?? 1970.

  9. Phonon transport in a one-dimensional harmonic chain with long-range interaction and mass disorder

    Science.gov (United States)

    Zhou, Hangbo; Zhang, Gang; Wang, Jian-Sheng; Zhang, Yong-Wei

    2016-11-01

    Atomic mass and interatomic interaction are the two key quantities that significantly affect the heat conduction carried by phonons. Here, we study the effects of long-range (LR) interatomic interaction and mass disorder on the phonon transport in a one-dimensional harmonic chain with up to 105 atoms. We find that while LR interaction reduces the transmission of low-frequency phonons, it enhances the transmission of high-frequency phonons by suppressing the localization effects caused by mass disorder. Therefore, LR interaction is able to boost heat conductance in the high-temperature regime or in the large size regime, where the high-frequency modes are important.

  10. State-of-the-art report on the theoretical modeling of interfacial area concentration

    International Nuclear Information System (INIS)

    Lee, Won Jae; Euh, Dong Jin

    1998-03-01

    Classical approaches based on experimental correlations and the mechanistic approaches based on the interfacial area concentration were reviewed. The study focuses on the state-of-the-art researches based on the mechanistic modeling of the interfacial area concentration. The investigation is performed by classifying the mechanistic modeling approaches into those using the number density transport equations supported with a simple algebraic relation for obtaining interfacial area concentration and those using the direct interfacial area transport equations. The modeling approaches are subdivided into one group and multi-group models. The state-of-the-art source terms of transport equations are also investigated for their applicability and limitations. (author). 62 refs., 6 tabs., 49 figs

  11. Additively manufactured metallic porous biomaterials based on minimal surfaces : A unique combination of topological, mechanical, and mass transport properties

    NARCIS (Netherlands)

    Bobbert, F S L; Lietaert, K; Eftekhari, A A; Pouran, B; Ahmadi, S M; Weinans, H; Zadpoor, A A

    2017-01-01

    Porous biomaterials that simultaneously mimic the topological, mechanical, and mass transport properties of bone are in great demand but are rarely found in the literature. In this study, we rationally designed and additively manufactured (AM) porous metallic biomaterials based on four different

  12. Analytical solution and simplified analysis of coupled parent-daughter steady-state transport with multirate mass transfer

    Science.gov (United States)

    R. Haggerty

    2013-01-01

    In this technical note, a steady-state analytical solution of concentrations of a parent solute reacting to a daughter solute, both of which are undergoing transport and multirate mass transfer, is presented. Although the governing equations are complicated, the resulting solution can be expressed in simple terms. A function of the ratio of concentrations, In (daughter...

  13. Improved performance of porous bio-anodes in microbial electrolysis cells by enhancing mass and charge transport

    NARCIS (Netherlands)

    Sleutels, T.H.J.A.; Lodder, R.; Hamelers, H.V.M.; Buisman, C.J.N.

    2009-01-01

    To create an efficient MEC high current densities and high coulombic efficiencies are required. The aim of this study was to increase cur-rent densities and coulombic efficiencies by influencing mass and charge transport in porous electrodes by: (i) introduction of a forced flow through the anode to

  14. Characterizing aerosol transport into the Canadian High Arctic using aerosol mass spectrometry and Lagrangian modelling

    Science.gov (United States)

    Kuhn, T.; Damoah, R.; Bacak, A.; Sloan, J. J.

    2010-05-01

    We report the analysis of measurements made using an aerosol mass spectrometer (AMS; Aerodyne Research Inc.) that was installed in the Polar Environment Atmospheric Research Laboratory (PEARL) in summer 2006. PEARL is located in the Canadian high Arctic at 610 m above sea level on Ellesmere Island (80° N 86° W). PEARL is unique for its remote location in the Arctic and because most of the time it is situated within the free troposphere. It is therefore well suited as a receptor site to study the long range tropospheric transport of pollutants into the Arctic. Some information about the successful year-round operation of an AMS at a high Arctic site such as PEARL will be reported here, together with design considerations for reliable sampling under harsh low-temperature conditions. Computational fluid dynamics calculations were made to ensure that sample integrity was maintained while sampling air at temperatures that average -40 °C in the winter and can be as low as -55 °C. Selected AMS measurements of aerosol mass concentration, size, and chemical composition recorded during the months of August, September and October 2006 will be reported. During this period, sulfate was at most times the predominant aerosol component with on average 0.115 μg m-3 (detection limit 0.003 μg m-3). The second most abundant component was undifferentiated organic aerosol, with on average 0.11 μg m-3 detection limit (0.04 μg m-3). The nitrate component, which averaged 0.007 μg m-3, was above its detection limit (0.002 μg m-3), whereas the ammonium ion had an apparent average concentration of 0.02 μg m-3, which was approximately equal to its detection limit. A few episodes having increased mass concentrations and lasting from several hours to several days are apparent in the data. These were investigated further using a statistical analysis to determine their common characteristics. High correlations among some of the components arriving during the short term episodes provide

  15. Extracellular mass transport considerations for space flight research concerning suspended and adherent in vitro cell cultures.

    Science.gov (United States)

    Klaus, David M; Benoit, Michael R; Nelson, Emily S; Hammond, Timmothy G

    2004-03-01

    Conducting biological research in space requires consideration be given to isolating appropriate control parameters. For in vitro cell cultures, numerous environmental factors can adversely affect data interpretation. A biological response attributed to microgravity can, in theory, be explicitly correlated to a specific lack of weight or gravity-driven motion occurring to, within or around a cell. Weight can be broken down to include the formation of hydrostatic gradients, structural load (stress) or physical deformation (strain). Gravitationally induced motion within or near individual cells in a fluid includes sedimentation (or buoyancy) of the cell and associated shear forces, displacement of cytoskeleton or organelles, and factors associated with intra- or extracellular mass transport. Finally, and of particular importance for cell culture experiments, the collective effects of gravity must be considered for the overall system consisting of the cells, their environment and the device in which they are contained. This does not, however, rule out other confounding variables such as launch acceleration, on orbit vibration, transient acceleration impulses or radiation, which can be isolated using onboard centrifuges or vibration isolation techniques. A framework is offered for characterizing specific cause-and-effect relationships for gravity-dependent responses as a function of the above parameters.

  16. Association of central serotonin transporter availability and body mass index in healthy Europeans

    DEFF Research Database (Denmark)

    Hesse, Swen; van de Giessen, Elsmarieke; Zientek, Franziska

    2014-01-01

    UNLABELLED: Serotonin-mediated mechanisms, in particular via the serotonin transporter (SERT), are thought to have an effect on food intake and play an important role in the pathophysiology of obesity. However, imaging studies that examined the correlation between body mass index (BMI) and SERT...... are sparse and provided contradictory results. The aim of this study was to further test the association between SERT and BMI in a large cohort of healthy subjects. METHODS: 127 subjects of the ENC DAT database (58 females, age 52 ± 18 years, range 20-83, BMI 25.2 ± 3.8 kg/m(2), range 18.2-41.1) were...... associated in the thalamus, but not in the midbrain. In the ROI-analysis, the interaction between gender and BMI showed a trend with higher correlation coefficient for men in the midbrain albeit not significant (0.033SBRm(2)/kg, p=0.1). CONCLUSIONS: The data are in agreement with previous PET findings...

  17. Microfluidic Transduction Harnesses Mass Transport Principles to Enhance Gene Transfer Efficiency.

    Science.gov (United States)

    Tran, Reginald; Myers, David R; Denning, Gabriela; Shields, Jordan E; Lytle, Allison M; Alrowais, Hommood; Qiu, Yongzhi; Sakurai, Yumiko; Li, William C; Brand, Oliver; Le Doux, Joseph M; Spencer, H Trent; Doering, Christopher B; Lam, Wilbur A

    2017-10-04

    Ex vivo gene therapy using lentiviral vectors (LVs) is a proven approach to treat and potentially cure many hematologic disorders and malignancies but remains stymied by cumbersome, cost-prohibitive, and scale-limited production processes that cannot meet the demands of current clinical protocols for widespread clinical utilization. However, limitations in LV manufacture coupled with inefficient transduction protocols requiring significant excess amounts of vector currently limit widespread implementation. Herein, we describe a microfluidic, mass transport-based approach that overcomes the diffusion limitations of current transduction platforms to enhance LV gene transfer kinetics and efficiency. This novel ex vivo LV transduction platform is flexible in design, easy to use, scalable, and compatible with standard cell transduction reagents and LV preparations. Using hematopoietic cell lines, primary human T cells, primary hematopoietic stem and progenitor cells (HSPCs) of both murine (Sca-1 + ) and human (CD34 + ) origin, microfluidic transduction using clinically processed LVs occurs up to 5-fold faster and requires as little as one-twentieth of LV. As an in vivo validation of the microfluidic-based transduction technology, HSPC gene therapy was performed in hemophilia A mice using limiting amounts of LV. Compared to the standard static well-based transduction protocols, only animals transplanted with microfluidic-transduced cells displayed clotting levels restored to normal. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  18. Long-range transport biomass burning emissions to the Himalayas: insights from high-resolution aerosol mass spectrometer

    Science.gov (United States)

    Xu, J.; Zhang, X.; Liu, Y.; Shichang, K.; Ma, Y.

    2017-12-01

    An intensive measurement was conducted at a remote, background, and high-altitude site (Qomolangma station, QOMS, 4276 m a.s.l.) in the northern Himalayas, using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) along with other collocated instruments. The field measurement was performed from April 12 to May 12, 2016 to chemically characterize high time-resolved submicron particulate matter (PM1) and obtain the influence of biomass burning emissions to the Himalayas, frequently transported from south Asia during pre-monsoon season. Two high aerosol loading periods were observed during the study. Overall, the average (± 1σ) PM1 mass concentration was 4.44 (± 4.54) µg m-3 for the entire study, comparable with those observed at other remote sites worldwide. Organic aerosols (OA) was the dominant PM1 species (accounting for 54.3% of total PM1 mass on average) and its contribution increased with the increase of total PM1 mass loading. The average size distributions of PM1 species all peaked at an overlapping accumulation mode ( 500 nm), suggesting that aerosol particles were internally well-mixed and aged during long-range transportations. Positive matrix factorization (PMF) analysis on the high-resolution organic mass spectra identified three distinct OA factors, including a biomass burning related OA (BBOA, 43.7%) and two oxygenated OA (Local-OOA and LRT-OOA; 13.9% and 42.4%) represented sources from local emissions and long-range transportations, respectively. Two polluted air mass origins (generally from the west and southwest of QOMS) and two polluted episodes with enhanced PM1 mass loadings and elevated BBOA contributions were observed, respectively, suggesting the important sources of wildfires from south Asia. One of polluted aerosol plumes was investigated in detail to illustrate the evolution of aerosol characteristics at QOMS driving by different impacts of wildfires, air mass origins, meteorological conditions and

  19. Mass-conserving tracer transport modelling on a reduced latitude-longitude grid with NIES-TM

    Directory of Open Access Journals (Sweden)

    D. Belikov

    2011-03-01

    Full Text Available The need to perform long-term simulations with reasonable accuracy has led to the development of mass-conservative and efficient numerical methods for solving the transport equation in forward and inverse models. We designed and implemented a flux-form (Eulerian tracer transport algorithm in the National Institute for Environmental Studies Transport Model (NIES TM, which is used for simulating diurnal and synoptic-scale variations of tropospheric long-lived constituents, as well as their seasonal and inter-annual variability. Implementation of the flux-form method requires the mass conservative wind fields. However, the model is off-line and is driven by datasets from a global atmospheric model or data assimilation system, in which vertically integrated mass changes are not in balance with the surface pressure tendency and mass conservation is not achieved. To rectify the mass-imbalance, a flux-correction method is employed. To avoid a singularity near the poles, caused by the small grid size arising from the meridional convergence problem, the proposed model uses a reduced latitude–longitude grid scheme, in which the grid size is doubled several times approaching the poles. This approach overcomes the Courant condition in the Polar Regions, maintains a reasonably high integration time-step, and ensures adequate model performance during simulations. To assess the model performance, we performed global transport simulations for SF6, 222Rn, and CO2. The results were compared with observations available from the World Data Centre for Greenhouse Gases, GLOBALVIEW, and the Hateruma monitoring station, Japan. Overall, the results show that the proposed flux-form version of NIES TM can produce tropospheric tracer transport more realistically than previously possible. The reasons for this improvement are discussed.

  20. An application of the 'end-point' method to the minimum critical mass problem in two group transport theory

    International Nuclear Information System (INIS)

    Williams, M.M.R.

    2003-01-01

    A two group integral equation derived using transport theory, which describes the fuel distribution necessary for a flat thermal flux and minimum critical mass, is solved by the classical end-point method. This method has a number of advantages and in particular highlights the changing behaviour of the fissile mass distribution function in the neighbourhood of the core-reflector interface. We also show how the reflector thermal flux behaves and explain the origin of the maximum which arises when the critical size is less than that corresponding to minimum critical mass. A comparison is made with diffusion theory and the necessary and somewhat artificial presence of surface delta functions in the fuel distribution is shown to be analogous to the edge transients that arise naturally in transport theory

  1. Separation Method for Oxygen Mass Transport Coefficient in Two Phase Porous Air Electrodes - Transport in Gas and Solid Polymer or Liquid Electrolyte Phases

    Science.gov (United States)

    2013-08-06

    of the problem studied Proton exchange membrane fuel cells ( PEMFCs ) are the most promising candidate systems for alternative electricity...characteristic. The limiting current can be used as a tool to study mass transport phenomena in PEMFC because it can provide experimental data for the...coefficient for PEMFCs under in situ conditions based on the galvanostatic discharge of a cell with an interrupted reactant supply. The results indicated

  2. Impact of Interfacial Layers in Perovskite Solar Cells.

    Science.gov (United States)

    Cho, An-Na; Park, Nam-Gyu

    2017-10-09

    Perovskite solar cells (PCSs) are composed of organic-inorganic lead halide perovskite as the light harvester. Since the first report on a long-term-durable, 9.7 % efficient, solid-state perovskite solar cell, organic-inorganic halide perovskites have received considerable attention because of their excellent optoelectronic properties. As a result, a power conversion efficiency (PCE) exceeding 22 % was certified. Controlling the grain size, grain boundary, morphology, and defects of the perovskite layer is important for achieving high efficiency. In addition, interfacial engineering is equally or more important to further improve the PCE through better charge collection and a reduction in charge recombination. In this Review, the type of interfacial layers and their impact on photovoltaic performance are investigated for both the normal and the inverted cell architectures. Four different interfaces of fluorine-doped tin oxide (FTO)/electron-transport layer (ETL), ETL/perovskite, perovskite/hole-transport layer (HTL), and HTL/metal are classified, and their roles are investigated. The effects of interfacial engineering with organic or inorganic materials on photovoltaic performance are described in detail. Grain-boundary engineering is also included because it is related to interfacial engineering and the grain boundary in the perovskite layer plays an important role in charge conduction, recombination, and chargecarrier life time. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Scaling of interfacial jump conditions

    International Nuclear Information System (INIS)

    Quezada G, S.; Vazquez R, A.; Espinosa P, G.

    2015-09-01

    To model the behavior of a nuclear reactor accurately is needed to have balance models that take into account the different phenomena occurring in the reactor. These balances have to be coupled together through boundary conditions. The boundary conditions have been studied and different treatments have been given to the interface. In this paper is a brief description of some of the interfacial jump conditions that have been proposed in recent years. Also, the scaling of an interfacial jump condition is proposed, for coupling the different materials that are in contact within a nuclear reactor. (Author)

  4. Developing effective mass transit systems : proceedings of the 5th International Workshop on Public Transportation

    Science.gov (United States)

    2007-09-01

    The Federal Transit Administration (FTA), in conjunction with the U.S. Embassy, the Russian Ministry of Transportation, the City of Moscow, and the Ministry of Transport of the Moscow Oblast (Regional) Government, hosted a bilateral conference to dis...

  5. Concept on groundwater flow and mass transport through heterogeneous porous media and application to in-situ test analysis

    International Nuclear Information System (INIS)

    Hatanaka, Koichiro; Umeki, Hiroyuki.

    1995-01-01

    Generally, geological media is modelled as porous or fractured media depending on their characteristics. Since the channels of groundwater flow and the transport paths are determined by the heterogeneity of the geological media, quantitative understanding of the heterogeneity is an important issue for modelling flow and transport processes through them. Therefore, it becomes popular way to develop statistical identification approaches of the heterogeneous field by using data from in-situ test and conduct validation studies of flow and transport models through the field by comparing with observed data. In this report, the theories of the identification approach and the concept on groundwater flow and mass transport are explained briefly and the application to tracer tests conducted at Grimsel test site, Switzerland, are described. (author)

  6. Modelling the effect of acoustic waves on the thermodynamics and kinetics of phase transformation in a solution: Including mass transportation.

    Science.gov (United States)

    Haqshenas, S R; Ford, I J; Saffari, N

    2018-01-14

    Effects of acoustic waves on a phase transformation in a metastable phase were investigated in our previous work [S. R. Haqshenas, I. J. Ford, and N. Saffari, "Modelling the effect of acoustic waves on nucleation," J. Chem. Phys. 145, 024315 (2016)]. We developed a non-equimolar dividing surface cluster model and employed it to determine the thermodynamics and kinetics of crystallisation induced by an acoustic field in a mass-conserved system. In the present work, we developed a master equation based on a hybrid Szilard-Fokker-Planck model, which accounts for mass transportation due to acoustic waves. This model can determine the kinetics of nucleation and the early stage of growth of clusters including the Ostwald ripening phenomenon. It was solved numerically to calculate the kinetics of an isothermal sonocrystallisation process in a system with mass transportation. The simulation results show that the effect of mass transportation for different excitations depends on the waveform as well as the imposed boundary conditions and tends to be noticeable in the case of shock waves. The derivations are generic and can be used with any acoustic source and waveform.

  7. Onsite well screening with a transportable gas chromatography/mass spectrometer system

    International Nuclear Information System (INIS)

    Rossabi, J.; Eckenrode, B.A.; Owens, B.

    1992-01-01

    The number of hazardous waste site operations continue to multiply. The requirements for efficient chemical assessment and monitoring of these sites become more stringent daily. As more samples are required, the time required for cleanup operations also increases and may make analytical costs prohibitive. Thus improvements in operation efficiency and reduction of cost in evaluating specific sites to minimize or eliminate their toxic effects on the surrounding environment are critical. For many years a formal policy did not exist for the disposal of waste solvents and other chemicals, thus many of these compounds were disposed of ensite. So long as these materials were contained onsite they were not considered to pose a threat to the surrounding environment. We have since determined that many of these compounds found their way into the groundwater. Contaminants such as trichloroethylene and perchloroethylene, which were heavily used for cleaning and degreasing purposes, must be monitored. Groundwater wells can be used to define the location and extent of the migration of any contaminant plume and aid in the determination of required cleanup. The major problem is that monitoring of hundreds of wells may be necessary, requiring several hundred samples on a quarterly basis to characterize the degree and extent of any contamination. Onsite analysis of monitoring wells for this characterization of waste operations could provide time savings and significant cost reduction. Field analyses can provide the required analytical results quickly and at a reduced cost without compromising either sample integrity or data quality. By using onsite analytical instrumentation, such as a field-transportable gas chromatograph/mass spectrometer (GC/MS), screening analyses can be performed to eliminate retturning to the laboratory with meaningless samples. Onsite GC/MS will provide qualitative or semi-quantitative information that can significantly simplify subsequent laboratory analyses

  8. A Numerical Model of Anisotropic Mass Transport Through Grain Boundary Networks

    Science.gov (United States)

    Wang, Yibo

    Tin (Sn) thin films are commonly used in electronic circuit applications as coatings on contacts and solders for joining components. It is widely observed, for some such system, that whiskers---long, thin crystalline structures---emerge and grow from the film. The Sn whisker phenomenon has become a highly active research area since Sn whiskers have caused a large amount of damage and loss in manufacturing, military, medical and power industries. Though lead (Pb) addition to Sn has been used to solve this problem for over five decades, the adverse environmental and health effects of Pb have motivated legislation to severely constrain Pb use in society. People are researching and seeking the reasons which cause whiskers and corresponding methods to solve the problem. The contributing factors to cause a Sn whisker are potentially many and much still remains unknown. Better understanding of fundamental driving forces should point toward strategies to improve (a) the accuracy with which we can predict whisker formation, and (b) our ability to mitigate the phenomenon. This thesis summarizes recent important research achievements in understanding Sn whisker formation and growth, both experimentally and theoretically. Focus is then placed on examining the role that anisotropy in grain boundary diffusivity plays in determining whisker characteristics (specifically, whether they form and, if so, where on a surface). To study this aspect of the problem and to enable future studies on stress driven grain boundary diffusion, this thesis presents a numerical anisotropic mass transport model. In addition to presenting details of the model and implementation, model predictions for a set of increasingly complex grain boundary networks are discussed. Preliminary results from the model provide evidence that anisotropic grain boundary diffusion may be a primary driving mechanism in whisker formation.

  9. Mass transport of direct methanol fuel cell species in sulfonated poly(ether ether ketone) membranes

    International Nuclear Information System (INIS)

    Silva, V.S.; Ruffmann, B.; Vetter, S.; Boaventura, M.; Mendes, A.M.; Madeira, L.M.; Nunes, S.P.

    2006-01-01

    Homogeneous membranes based on sulfonated poly(ether ether ketone) (sPEEK) with different sulfonation degrees (SD) were prepared and characterized. In order to perform a critical analysis of the SD effect on the polymer barrier and mass transport properties towards direct methanol fuel cell species, proton conductivity, water/methanol pervaporation and nitrogen/oxygen/carbon dioxide pressure rise method experiments are proposed. This procedure allows the evaluation of the individual permeability coefficients in hydrated sPEEK membranes with different sulfonation degrees. Nafion[reg] 112 was used as reference material. DMFC tests were also performed at 50 deg. C. It was observed that the proton conductivity and the permeability towards water, methanol, oxygen and carbon dioxide increase with the sPEEK sulfonation degree. In contrast, the SD seems to not affect the nitrogen permeability coefficient. In terms of selectivity, it was observed that the carbon dioxide/oxygen selectivity increases with the sPEEK SD. In contrast, the nitrogen/oxygen selectivity decreases. In terms of barrier properties for preventing the DMFC reactants loss, the polymer electrolyte membrane based on the sulfonated poly(ether ether ketone) with SD lower or equal to 71%, although having slightly lower proton conductivity, presented much better characteristics for fuel cell applications compared with the well known Nafion[reg] 112. In terms of the DMFC tests of the studied membranes at low temperature, the sPEEK membrane with SD = 71% showed to have similar performance, or even better, as that of Nafion[reg] 112. However, the highest DMFC overall efficiency was achieved using sPEEK membrane with SD = 52%

  10. Interfacial and Surface Science | Materials Science | NREL

    Science.gov (United States)

    Science group within the Material Science Center. He oversees research studies of surfaces and interfaces Interfacial and Surface Science Interfacial and Surface Science Image of irregular-outlined, light address a broad range of fundamental and applied issues in surface and interfacial science that are

  11. Effects of radiation transport on mass ablation rate and conversion efficiency in numerical simulations of inertial confinement fusion

    International Nuclear Information System (INIS)

    Gupta, N.K.

    2002-01-01

    The effects of radiation transport on hydrodynamic parameters of laser produced plasmas are studied. LTE and non-LTE atomic models are used to calculate multi group opacities and emissivities. Screened hydrogenic atom model is used to calculate the energy levels. The population densities of neutral to fully ionized ions are obtained by solving the steady state rate equations. Radiation transport is treated in multi-group diffusion or Sn method. A comparison is made between 1 and 100 group radiation transport and LTE and non-LTE models. For aluminium, multi group radiation transport leads to much higher mass ablation as compared to the 1 group and no radiation transport cases. This in turn leads to higher ablation pressures. However, for gold gray approximation gives higher mass ablation as compared to multi group simulations. LTE conversion efficiency of laser light into x-rays is more than the non-LTE estimates. For LTE as well as non-LTE cases, the one group approximation over-predicts the conversion efficiency Multi group non-LTE simulations predict that the conversion efficiency increases with laser intensity up to a maximum and then it decreases. (author)

  12. Dentin-cement Interfacial Interaction

    Science.gov (United States)

    Atmeh, A.R.; Chong, E.Z.; Richard, G.; Festy, F.; Watson, T.F.

    2012-01-01

    The interfacial properties of a new calcium-silicate-based coronal restorative material (Biodentine™) and a glass-ionomer cement (GIC) with dentin have been studied by confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), micro-Raman spectroscopy, and two-photon auto-fluorescence and second-harmonic-generation (SHG) imaging. Results indicate the formation of tag-like structures alongside an interfacial layer called the “mineral infiltration zone”, where the alkaline caustic effect of the calcium silicate cement’s hydration products degrades the collagenous component of the interfacial dentin. This degradation leads to the formation of a porous structure which facilitates the permeation of high concentrations of Ca2+, OH-, and CO32- ions, leading to increased mineralization in this region. Comparison of the dentin-restorative interfaces shows that there is a dentin-mineral infiltration with the Biodentine, whereas polyacrylic and tartaric acids and their salts characterize the penetration of the GIC. A new type of interfacial interaction, “the mineral infiltration zone”, is suggested for these calcium-silicate-based cements. PMID:22436906

  13. Interfacial behaviour of biopolymer multilayers

    NARCIS (Netherlands)

    Corstens, Meinou N.; Osorio Caltenco, Lilia A.; Vries, de Renko; Schroën, Karin; Berton-Carabin, Claire C.

    2017-01-01

    Although multilayered emulsions have been related to reduced lipolysis, the involved interfacial phenomena have never been studied directly. In this work, we systematically built multilayers of whey protein and pectin, which we further subjected to digestive conditions, using two different

  14. Chemical mass transport between fluid fine tailings and the overlying water cover of an oil sands end pit lake

    Science.gov (United States)

    Dompierre, Kathryn A.; Barbour, S. Lee; North, Rebecca L.; Carey, Sean K.; Lindsay, Matthew B. J.

    2017-06-01

    Fluid fine tailings (FFT) are a principal by-product of the bitumen extraction process at oil sands mines. Base Mine Lake (BML)—the first full-scale demonstration oil sands end pit lake (EPL)—contains approximately 1.9 × 108 m3 of FFT stored under a water cover within a decommissioned mine pit. Chemical mass transfer from the FFT to the water cover can occur via two key processes: (1) advection-dispersion driven by tailings settlement; and (2) FFT disturbance due to fluid movement in the water cover. Dissolved chloride (Cl) was used to evaluate the water cover mass balance and to track mass transport within the underlying FFT based on field sampling and numerical modeling. Results indicated that FFT was the dominant Cl source to the water cover and that the FFT is exhibiting a transient advection-dispersion mass transport regime with intermittent disturbance near the FFT-water interface. The advective pore water flux was estimated by the mass balance to be 0.002 m3 m-2 d-1, which represents 0.73 m of FFT settlement per year. However, the FFT pore water Cl concentrations and corresponding mass transport simulations indicated that advection rates and disturbance depths vary between sample locations. The disturbance depth was estimated to vary with location between 0.75 and 0.95 m. This investigation provides valuable insight for assessing the geochemical evolution of the water cover and performance of EPLs as an oil sands reclamation strategy.

  15. Comparison of mass transport using average and transient rainfall boundary conditions

    International Nuclear Information System (INIS)

    Duguid, J.O.; Reeves, M.

    1976-01-01

    A general two-dimensional model for simulation of saturated-unsaturated transport of radionuclides in ground water has been developed and is currently being tested. The model is being applied to study the transport of radionuclides from a waste-disposal site where field investigations are currently under way to obtain the necessary model parameters. A comparison of the amount of tritium transported is made using both average and transient rainfall boundary conditions. The simulations indicate that there is no substantial difference in the transport for the two conditions tested. However, the values of dispersivity used in the unsaturated zone caused more transport above the water table than has been observed under actual conditions. This deficiency should be corrected and further comparisons should be made before average rainfall boundary conditions are used for long-term transport simulations

  16. Status of the nation's local mass transportation: performance and conditions. Report to the congress, June 1988. Biennial report

    Energy Technology Data Exchange (ETDEWEB)

    1988-06-01

    This document is the third biennial Report of the Secretary of Transportation to the United States Congress on the current performance and condition of the Nation's public mass-transportation systems. It updates the information and recommendations of the previous report and should be of value to the Congress and the Department for developing policy and program requirements to administer the Federal mass-transportation assistance program.

  17. An inexact Newton method for fully-coupled solution of the Navier-Stokes equations with heat and mass transport

    Energy Technology Data Exchange (ETDEWEB)

    Shadid, J.N.; Tuminaro, R.S. [Sandia National Labs., Albuquerque, NM (United States); Walker, H.F. [Utah State Univ., Logan, UT (United States). Dept. of Mathematics and Statistics

    1997-02-01

    The solution of the governing steady transport equations for momentum, heat and mass transfer in flowing fluids can be very difficult. These difficulties arise from the nonlinear, coupled, nonsymmetric nature of the system of algebraic equations that results from spatial discretization of the PDEs. In this manuscript the authors focus on evaluating a proposed nonlinear solution method based on an inexact Newton method with backtracking. In this context they use a particular spatial discretization based on a pressure stabilized Petrov-Galerkin finite element formulation of the low Mach number Navier-Stokes equations with heat and mass transport. The discussion considers computational efficiency, robustness and some implementation issues related to the proposed nonlinear solution scheme. Computational results are presented for several challenging CFD benchmark problems as well as two large scale 3D flow simulations.

  18. Optical conductivity and optical effective mass in a high-mobility organic semiconductor: Implications for the nature of charge transport

    KAUST Repository

    Li, Yuan

    2014-12-03

    We present a multiscale modeling of the infrared optical properties of the rubrene crystal. The results are in very good agreement with the experimental data that point to nonmonotonic features in the optical conductivity spectrum and small optical effective masses. We find that, in the static-disorder approximation, the nonlocal electron-phonon interactions stemming from low-frequency lattice vibrations can decrease the optical effective masses and lead to lighter quasiparticles. On the other hand, the charge-transport and infrared optical properties of the rubrene crystal at room temperature are demonstrated to be governed by localized carriers driven by inherent thermal disorders. Our findings underline that the presence of apparently light carriers in high-mobility organic semiconductors does not necessarily imply bandlike transport.

  19. A numerical study of transient mass transport through a circular hole connecting two semi-infinite media

    International Nuclear Information System (INIS)

    DePaoli, D.W.; Scott, T.C.

    1993-01-01

    A numerical model of transient diffusive mass transfer through a circular hole that connects two semi-infinite media was used as a means of determining potential effects of waste container penetrations on the release of immobilized contaminants into the environment. The finite difference model as developed necessarily includes treatment of mass transport in both the waste and surrounding medium and allows calculation of release rates for cases with and without preferential adsorption and differing diffusivities of the two media. The dimensionless contaminant release rate was found to vary over several orders of magnitude depending on the product of the ratio of the distribution coefficient and the media diffusivities only. As would be intuitively expected, partitioning favoring the surrounding medium and higher relative waste medium diffusivity cause higher transport rates. There was definitely no unexpected enhancement in the release rate in the case of perforations over that of an uncontained waste form

  20. Optical conductivity and optical effective mass in a high-mobility organic semiconductor: Implications for the nature of charge transport

    KAUST Repository

    Li, Yuan; Yi, Yuanping; Coropceanu, Veaceslav; Bredas, Jean-Luc

    2014-01-01

    We present a multiscale modeling of the infrared optical properties of the rubrene crystal. The results are in very good agreement with the experimental data that point to nonmonotonic features in the optical conductivity spectrum and small optical effective masses. We find that, in the static-disorder approximation, the nonlocal electron-phonon interactions stemming from low-frequency lattice vibrations can decrease the optical effective masses and lead to lighter quasiparticles. On the other hand, the charge-transport and infrared optical properties of the rubrene crystal at room temperature are demonstrated to be governed by localized carriers driven by inherent thermal disorders. Our findings underline that the presence of apparently light carriers in high-mobility organic semiconductors does not necessarily imply bandlike transport.

  1. Influence of a thermal gradient on water-rock interactions and mass transport in geologic media (marine pelagic clay)

    International Nuclear Information System (INIS)

    Seyfried, W.E. Jr.

    1985-01-01

    A brief outline of the role of thermodiffusional processes in mass transport and sediment alteration for a sediment/seawater system that is subjected to a thermal gradient and maximum temperature and pressure condition, such as in a subseabed repository is presented. The author underscores the need to investigate the effect of basic physical and chemical parameters on Soret coefficients for various electrolyte fluids. Such experiments will require the design and development of unique hydrothermal apparatus

  2. Effect of Mass Transport in the Synthesis of Partially Acetylated Dendrimer: Implications for Functional Ligand–Nanoparticle Distributions

    OpenAIRE

    Mullen, Douglas G.; Borgmeier, Emilee L.; Fang, Ming; McNerny, Daniel Q.; Desai, Ankur; Baker, James R.; Orr, Bradford G.; Holl, Mark M. Banaszak

    2010-01-01

    Partial acetylation of the amine-terminated poly(amidoamine) dendrimer has been used in the preparation of dendrimer particles conjugated with a wide variety of functional ligands including targeting moieties, therapeutic agents, and dye molecules. The effectiveness of mass transport during the partial acetylation reaction was found to have a major effect on subsequent distributions of dendrimer–ligand components and to be a major source of inconsistency between batches. This study has broad ...

  3. Mass transport in low permeability rocks under the influence of coupled thermomechanical and hydrochemical effects - an overview

    International Nuclear Information System (INIS)

    Tsang, C.F.

    1984-10-01

    The present paper gives a general overview of mass transport in low permeability rocks under the coupled thermomechanical and hydrochemical effects associated with a nuclear waste repository. A classification of coupled processes is given. Then an ess is presented. example of a coupled process is presented. Discussions of coupled processes based on a recent LBL Panel meeting are summarized. 5 references, 3 figures, 4 tables

  4. Pore scale study of multiphase multicomponent reactive transport during CO2 dissolution trapping

    Science.gov (United States)

    Chen, Li; Wang, Mengyi; Kang, Qinjun; Tao, Wenquan

    2018-06-01

    Solubility trapping is crucial for permanent CO2 sequestration in deep saline aquifers. For the first time, a pore-scale numerical method is developed to investigate coupled scCO2-water two-phase flow, multicomponent (CO2(aq), H+, HCO3-, CO32- and OH-) mass transport, heterogeneous interfacial dissolution reaction, and homogeneous dissociation reactions. Pore-scale details of evolutions of multiphase distributions and concentration fields are presented and discussed. Time evolutions of several variables including averaged CO2(aq) concentration, scCO2 saturation, and pH value are analyzed. Specific interfacial length, an important variable which cannot be determined but is required by continuum models, is investigated in detail. Mass transport coefficient or efficient dissolution rate is also evaluated. The pore-scale results show strong non-equilibrium characteristics during solubility trapping due to non-uniform distributions of multiphase as well as slow mass transport process. Complicated coupling mechanisms between multiphase flow, mass transport and chemical reactions are also revealed. Finally, effects of wettability are also studied. The pore-scale studies provide deep understanding of non-linear non-equilibrium multiple physicochemical processes during CO2 solubility trapping processes, and also allow to quantitatively predict some important empirical relationships, such as saturation-interfacial surface area, for continuum models.

  5. Apparent directional mass-transfer capacity coefficients in three-dimensional anisotropic heterogeneous aquifers under radial convergent transport

    Science.gov (United States)

    Pedretti, D.; Fernàndez-Garcia, D.; Sanchez-Vila, X.; Bolster, D.; Benson, D. A.

    2014-02-01

    Aquifer hydraulic properties such as hydraulic conductivity (K) are ubiquitously heterogeneous and typically only a statistical characterization can be sought. Additionally, statistical anisotropy at typical characterization scales is the rule. Thus, regardless of the processes governing solute transport at the local (pore) scale, transport becomes non-Fickian. Mass-transfer models provide an efficient tool that reproduces observed anomalous transport; in some cases though, these models lack predictability as model parameters cannot readily be connected to the physical properties of aquifers. In this study, we focus on a multirate mass-transfer model (MRMT), and in particular the apparent capacity coefficient (β), which is a strong indicator of the potential of immobile zones to capture moving solute. We aim to find if the choice of an apparent β can be phenomenologically related to measures of statistical anisotropy. We analyzed an ensemble of random simulations of three-dimensional log-transformed multi-Gaussian permeability fields with stationary anisotropic correlation under convergent flow conditions. It was found that apparent β also displays an anisotropic behavior, physically controlled by the aquifer directional connectivity, which in turn is controlled by the anisotropic correlation model. A high hydraulic connectivity results in large β values. These results provide new insights into the practical use of mass-transfer models for predictive purposes.

  6. Ozone-surface interactions: Investigations of mechanisms, kinetics, mass transport, and implications for indoor air quality

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, Glenn Charles [Univ. of California, Berkeley, CA (United States)

    1999-12-01

    In this dissertation, results are presented of laboratory investigations and mathematical modeling efforts designed to better understand the interactions of ozone with surfaces. In the laboratory, carpet and duct materials were exposed to ozone and measured ozone uptake kinetics and the ozone induced emissions of volatile organic compounds. To understand the results of the experiments, mathematical methods were developed to describe dynamic indoor aldehyde concentrations, mass transport of reactive species to smooth surfaces, the equivalent reaction probability of whole carpet due to the surface reactivity of fibers and carpet backing, and ozone aging of surfaces. Carpets, separated carpet fibers, and separated carpet backing all tended to release aldehydes when exposed to ozone. Secondary emissions were mostly n-nonanal and several other smaller aldehydes. The pattern of emissions suggested that vegetable oils may be precursors for these oxidized emissions. Several possible precursors and experiments in which linseed and tung oils were tested for their secondary emission potential were discussed. Dynamic emission rates of 2-nonenal from a residential carpet may indicate that intermediate species in the oxidation of conjugated olefins can significantly delay aldehyde emissions and act as reservoir for these compounds. The ozone induced emission rate of 2-nonenal, a very odorous compound, can result in odorous indoor concentrations for several years. Surface ozone reactivity is a key parameter in determining the flux of ozone to a surface, is parameterized by the reaction probability, which is simply the probability that an ozone molecule will be irreversibly consumed when it strikes a surface. In laboratory studies of two residential and two commercial carpets, the ozone reaction probability for carpet fibers, carpet backing and the equivalent reaction probability for whole carpet were determined. Typically reaction probability values for these materials were 10

  7. Biomonitor-Reflection of Large-Distance Air Mass Transported Trace Elements

    NARCIS (Netherlands)

    Henriques Vieira, B.J.

    2017-01-01

    The present thesis’ topic is the biomonitoring of atmospheric trace elements with attention focused on the long-range transported trace elements. The aim was to provide improved understanding of aerosol characteristics under the atmospheric transport dynamics of Central North Atlantic at different

  8. Recent advances in interfacial engineering of perovskite solar cells

    Science.gov (United States)

    Ye, Meidan; He, Chunfeng; Iocozzia, James; Liu, Xueqin; Cui, Xun; Meng, Xiangtong; Rager, Matthew; Hong, Xiaodan; Liu, Xiangyang; Lin, Zhiqun

    2017-09-01

    Due to recent developments, organometallic halide perovskite solar cells (PSCs) have attracted even greater interest owing to their impressive photovoltaic properties and simple device manufacturing processes with the potential for commercial applications. The power conversion efficiencies (PCEs) of PSCs have surged from 3.8% for methyl ammonium lead halide-sensitized liquid solar cells, CH3NH3PbX3 (X  =  Cl, Br, I), in 2009, to more than 22% for all-solid-state solar cells in 2016. Over the past few years, significant effort has been dedicated to realizing PSCs with even higher performance. In this review, recent advances in the interfacial engineering of PSCs are addressed. The specific strategies for the interfacial engineering of PSCs fall into two categories: (1) solvent treatment and additives to improve the light-harvesting capabilities of perovskite films, and (2) the incorporation of various functional materials at the interfaces between the active layers (e.g. electron transporting layer, perovskite layer, and hole transporting layer). This review aims to provide a comprehensive overview of strategies for the interfacial engineering of PSCs with potential benefits including enhanced light harvesting, improved charge separation and transport, improved device stability, and elimination of photocurrent hysteresis.

  9. Transport of mass goods on the top run and bottom run of belt conveyors

    Energy Technology Data Exchange (ETDEWEB)

    Zimmermann, D

    1977-06-01

    For combined coal winning from the collieries 'General Blumenthal' and 'Ewald Fortsetzung' a large belt conveyor plant was taken into operation which is able to transport 1360 tons/h in the top run and 300 tons/h of dirt in the bottom run. The different types of coal are transported separately in intermittent operation with the aid of bunker systems connected to the front and rear of the belt conveyor. Persons can be transported in the top run as well as in the bottom run.

  10. The analysis of interfacial waves

    International Nuclear Information System (INIS)

    Galimov, Azat Yu.; Drew, Donald A.; Lahey, Richard T.; Moraga, Francisco J.

    2005-01-01

    We present analytical results for stable stratified wavy two-phase flow and functional forms for the various interfacial force densities in a two-fluid model. In particular, we have derived analytically the components of the non-drag interfacial force density [Drew, D.A., Passman, S.L., 1998. Theory of Multicomponent Fluids. Springer-Verlag, New York; Nigmatulin, T.R., Drew, D.A., Lahey, R.T., Jr., 2000. An analysis of wavy annular flow. In: International Conference on Multiphase Systems, ICMS'2000, Ufa, Russia, June 15-17], Reynolds stress tensor, and the term, (p-bar cl i -p-bar cl )-bar α cl , where p-bar cl i is interfacial average pressure, p-bar cl the average pressure, and α cl is the volume fraction of the continuous liquid phase. These functional forms should be useful for assessing two-fluid closure relations and Computational Multiphase Fluid Dynamics (CMFD) numerical models for stratified wavy flows. Moreover, it appears that this approach can be generalized to other flow regimes (e.g., annular flows)

  11. Variability in Mass Spectrometry-based Quantification of Clinically Relevant Drug Transporters and Drug Metabolizing Enzymes

    NARCIS (Netherlands)

    Wegler, C.; Gaugaz, F.Z.; Andersson, T.B.; Wiśniewski, J.R.; Busch, D.; Gröer, C.; Oswald, S.; Norén, A.; Weiss, F.; Hammer, H.S.; Joos, T.O.; Poetz, O.; Achour, B.; Rostami-Hodjegan, A.; Steeg, E. van de; Wortelboer, H.M.; Artursson, P.

    2017-01-01

    Many different methods are used for mass-spectrometry-based protein quantification in pharmacokinetics and systems pharmacology. It has not been established to what extent the results from these various methods are comparable. Here, we compared six different mass spectrometry-based proteomics

  12. Optimal Mass Transport for Statistical Estimation, Image Analysis, Information Geometry, and Control

    Science.gov (United States)

    2017-01-10

    advances on formulating and solving optimal transport problems on discrete spaces (networks) while ensuring robustness of the transportation plan. This...Metric Uncertainty for Spectral Estimation based on Nevanlinna-Pick Interpolation, (with J. Karlsson) Intern. Symp. on the Math . Theory of Networks and...Systems, Melbourne 2012. 22. Geometric tools for the estimation of structured covariances, (with L. Ning, X. Jiang) Intern. Symposium on the Math . Theory

  13. Sintering kinetics and mass transport in ceramic engobes; Cinetica de sinterizacion y transporte de masa en engobes ceramicos por el metodo Pechini

    Energy Technology Data Exchange (ETDEWEB)

    Dal Bo, M.; Boschi, A. O.; Hotza, D.

    2013-10-01

    This work is concerned to study the sintering rate and mass transport mechanism in ceramic engobes. Specimens of engobes were prepared from a determined formulation by slip casting. Sintering was carried in two steps: (i) at constant heating rate of 7.5 degree centigrade/min and (ii) with an isothermal treatment, during 120 min. According to the dilatometric curves obtained with the engobe sintering during isothermal treatment, the dominant sintering mechanism and the rate of reactions, between the 775 and 975 degree centigrade, were determined. The results showed that between 775 and 800 degree centigrade, the sintering rate can be described by ln[d({Delta}L/L{sub 0})/dt] = -5.64 + 1.77.E10{sup -}3T. At higher temperatures, from 850 to 975 degree centigrade, this rate can be expressed by ln[d({Delta}L/L{sub 0})/ dt] = -30.73 + 3.E10{sup -}2T. The dominant transport mass mechanisms were the grain rearrangement, solution-precipitation and grain boundaries reaction. (Author)

  14. Commuter exposure to black carbon, carbon monoxide, and noise in the mass transport khlong boats of Bangkok, Thailand

    Science.gov (United States)

    Ziegler, A. D.; Velasco, E.; Ho, K. J.

    2013-12-01

    Khlong (canal) boats are a unique mass transport alternative in the congested city of Bangkok. Canals and rivers provide exclusive transit-ways for reducing the commuting time of thousands of city residents daily. However, as a consequence of the service characteristics and boats design and state of repair, they can represent a potential public health risk and an important source of black carbon and greenhouse gases. This work quantifies commuter exposure to black carbon, CO and noise when waiting for and travelling in these diesel fueled boats. Exposure to toxic pollutants and acute noise is similar or worse than for other transportation modes. Mean black carbon concentrations observed at one busy pier and along the main canal were much higher than ambient concentrations at sites impacted by vehicular traffic. Concentrations of CO were similar to those reported for roadside areas of Bangkok. The equivalent continuous sound levels registered at the landing pier were similar to those reported for roadsides, but values recorded inside the boats were significantly higher. We believe that the boat service is a viable alternative mode of mass transport, but public safety could be improved to provide a high quality service, comparable to modern rail systems or emerging bus rapid transit systems. These investments would also contribute to reduce the emission of black carbon and other greenhouse and toxic pollutants.

  15. Interfacial effect on physical properties of composite media: Interfacial volume fraction with non-spherical hard-core-soft-shell-structured particles.

    Science.gov (United States)

    Xu, Wenxiang; Duan, Qinglin; Ma, Huaifa; Chen, Wen; Chen, Huisu

    2015-11-02

    Interfaces are known to be crucial in a variety of fields and the interfacial volume fraction dramatically affects physical properties of composite media. However, it is an open problem with great significance how to determine the interfacial property in composite media with inclusions of complex geometry. By the stereological theory and the nearest-surface distribution functions, we first propose a theoretical framework to symmetrically present the interfacial volume fraction. In order to verify the interesting generalization, we simulate three-phase composite media by employing hard-core-soft-shell structures composed of hard mono-/polydisperse non-spherical particles, soft interfaces, and matrix. We numerically derive the interfacial volume fraction by a Monte Carlo integration scheme. With the theoretical and numerical results, we find that the interfacial volume fraction is strongly dependent on the so-called geometric size factor and sphericity characterizing the geometric shape in spite of anisotropic particle types. As a significant interfacial property, the present theoretical contribution can be further drawn into predicting the effective transport properties of composite materials.

  16. Heat, mass, and momentum transport model for hydrogen diffusion flames in nuclear reactor containments

    International Nuclear Information System (INIS)

    Travis, J.R.

    1985-01-01

    It is now possible to analyze the time-dependent, fully three-dimensional behavior of hydrogen diffusion flames in nuclear reactor containments. This analysis involves coupling the full Navier-Stokes equations with multi-species transport to the global chemical kinetics of hydrogen combustion. A transport equation for the subgrid scale turbulent kinetic energy density is solved to produce the time and space dependent turbulent transport coefficients. The heat transfer coefficient governing the exchange of heat between fluid computational cells adjacent to wall cells is calculated by a modified Reynolds analogy formulation. The analysis of a MARK-III containment indicates very complex flow patterns that greatly influence fluid and wall temperatures and heat fluxes. 18 refs., 24 figs

  17. Overexpression and deletion of phospholipid transfer protein reduce HDL mass and cholesterol efflux capacity but not macrophage reverse cholesterol transport[S

    Science.gov (United States)

    Kuwano, Takashi; Bi, Xin; Cipollari, Eleonora; Yasuda, Tomoyuki; Lagor, William R.; Szapary, Hannah J.; Tohyama, Junichiro; Millar, John S.; Billheimer, Jeffrey T.; Lyssenko, Nicholas N.; Rader, Daniel J.

    2017-01-01

    Phospholipid transfer protein (PLTP) may affect macrophage reverse cholesterol transport (mRCT) through its role in the metabolism of HDL. Ex vivo cholesterol efflux capacity and in vivo mRCT were assessed in PLTP deletion and PLTP overexpression mice. PLTP deletion mice had reduced HDL mass and cholesterol efflux capacity, but unchanged in vivo mRCT. To directly compare the effects of PLTP overexpression and deletion on mRCT, human PLTP was overexpressed in the liver of wild-type animals using an adeno-associated viral (AAV) vector, and control and PLTP deletion animals were injected with AAV-null. PLTP overexpression and deletion reduced plasma HDL mass and cholesterol efflux capacity. Both substantially decreased ABCA1-independent cholesterol efflux, whereas ABCA1-dependent cholesterol efflux remained the same or increased, even though preβ HDL levels were lower. Neither PLTP overexpression nor deletion affected excretion of macrophage-derived radiocholesterol in the in vivo mRCT assay. The ex vivo and in vivo assays were modified to gauge the rate of cholesterol efflux from macrophages to plasma. PLTP activity did not affect this metric. Thus, deviations in PLTP activity from the wild-type level reduce HDL mass and ex vivo cholesterol efflux capacity, but not the rate of macrophage cholesterol efflux to plasma or in vivo mRCT. PMID:28137768

  18. Transportation

    National Research Council Canada - National Science Library

    Adams, James; Carr, Ron; Chebl, Maroun; Coleman, Robert; Costantini, William; Cox, Robert; Dial, William; Jenkins, Robert; McGovern, James; Mueller, Peter

    2006-01-01

    ...., trains, ships, etc.) and maximizing intermodal efficiency. A healthy balance must be achieved between the flow of international commerce and security requirements regardless of transportation mode...

  19. A desk study of surface diffusion and mass transport in clay

    International Nuclear Information System (INIS)

    Cook, A.J.

    1989-01-01

    Research into the properties of clays as barrier materials for nuclear waste disposal has led to the realization that they have important transport properties which are relatively insignificant in most other geological materials. Sorption has always been regarded as a purely retarding mechanism, but laboratory experiments over the past decade have indicated that surface diffusion of sorbed cations is a potentially significant transport mechanism in both compacted montmorillonite, and biotite gneiss. The present desk study about these issues was part of the CEC coordinated project Mirage-Second phase, research area Natural analogues

  20. Interfacial reactions between titanium and borate glass

    Energy Technology Data Exchange (ETDEWEB)

    Brow, R.K. [Sandia National Labs., Albuquerque, NM (United States); Saha, S.K.; Goldstein, J.I. [Lehigh Univ., Bethlehem, PA (United States). Dept. of Materials Science

    1992-12-31

    Interfacial reactions between melts of several borate glasses and titanium have been investigated by analytical scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS). A thin titanium boride interfacial layer is detected by XPS after short (30 minutes) thermal treatments. ASEM analyses after longer thermal treatments (8--120 hours) reveal boron-rich interfacial layers and boride precipitates in the Ti side of the interface.

  1. Interfacial structures in confined cap-turbulent and churn-turbulent flows

    International Nuclear Information System (INIS)

    Sun Xiaodong; Kim, Seungjin; Cheng Ling; Ishii, Mamoru; Beus, Stephen G.

    2004-01-01

    The objective of the present work is to study and model the interfacial structure development of air-water two-phase flow in a confined flow passage. Experiments of a total of 13 flow conditions in cap-turbulent and churn-turbulent flow regimes are carried out in a vertical air-water upward two-phase flow experimental loop with a test section of 200 mm in width and 10 mm in gap. Miniaturized four-sensor conductivity probes are used to measure local two-phase parameters at three different elevations for each flow condition. Bubble characteristics captured by the probes are categorized into two groups in view of the two-group interfacial area transport equation, i.e., spherical/distorted bubbles as Group 1 and cap/churn-turbulent bubbles as Group 2. The acquired local parameters are time-averaged void fraction, interfacial velocity, bubble number frequency, interfacial area concentration, and bubble Sauter mean diameter for each group of bubbles. Also, the line-averaged and area-averaged data are presented and discussed in detail. The comparisons of these parameters at different elevations demonstrate the development of interfacial structures along the flow direction due to bubble interactions and the hydrodynamic effects. Furthermore, these data can serve as one part of the experimental data for investigation of the interfacial area transport in a confined two-phase flow

  2. Multi-layer membrane model for mass transport in a direct ethanol fuel cell using an alkaline anion exchange membrane

    Science.gov (United States)

    Bahrami, Hafez; Faghri, Amir

    2012-11-01

    A one-dimensional, isothermal, single-phase model is presented to investigate the mass transport in a direct ethanol fuel cell incorporating an alkaline anion exchange membrane. The electrochemistry is analytically solved and the closed-form solution is provided for two limiting cases assuming Tafel expressions for both oxygen reduction and ethanol oxidation. A multi-layer membrane model is proposed to properly account for the diffusive and electroosmotic transport of ethanol through the membrane. The fundamental differences in fuel crossover for positive and negative electroosmotic drag coefficients are discussed. It is found that ethanol crossover is significantly reduced upon using an alkaline anion exchange membrane instead of a proton exchange membrane, especially at current densities higher than 500 A m

  3. Nitrogen transport, transformation, and retention in the Three Gorges Reservoir : A mass balance approach

    NARCIS (Netherlands)

    Ran, Xiangbin; Bouwman, Lex; Yu, Zhigang; Beusen, Arthur; Chen, Hongtao; Yao, Qingzhen

    2017-01-01

    Dam construction in river systems affects the biogeochemistry of nitrogen (N), yet most studies on N cycling in reservoirs do not consider the transformations and retention of the different N species. This study addresses the N inputs, transport, transformations, and retention in the Three Gorges

  4. Development of a multi-species mass transport model for concrete with account to thermodynamic phase equilibriums

    DEFF Research Database (Denmark)

    Hosokawa, Yoshifumi; Yamada, Kazuo; Johannesson, Björn

    2011-01-01

    different types of cements. For example, the physicochemical evaluation of steel corrosion initiation can be studied by calculating the molar ratio of chloride ion to hydroxide ion in the pore solution. The model can, further, for example, calculate changes of solid-phase composition caused......) theory alone, not involving chemical processes, have no real practical interest since the chemical action is very dominant for cement based materials. Coupled mass transport and chemical equilibrium models can be used to calculate the variation in pore solution and solid-phase composition when using...

  5. Final Report: Mass Production Cost Estimation of Direct H2 PEM Fuel Cell Systems for Transportation Applications (2012-2016)

    Energy Technology Data Exchange (ETDEWEB)

    James, Brian David [Strategic Analysis Inc., Arlington, VA (United States); Huya-Kouadio, Jennie Moton [Strategic Analysis Inc., Arlington, VA (United States); Houchins, Cassidy [Strategic Analysis Inc., Arlington, VA (United States); DeSantis, Daniel Allen [Strategic Analysis Inc., Arlington, VA (United States)

    2016-09-01

    This report summarizes project activities for Strategic Analysis, Inc. (SA) Contract Number DE-EE0005236 to the U.S. Department of Energy titled “Transportation Fuel Cell System Cost Assessment”. The project defined and projected the mass production costs of direct hydrogen Proton Exchange Membrane fuel cell power systems for light-duty vehicles (automobiles) and 40-foot transit buses. In each year of the five-year contract, the fuel cell power system designs and cost projections were updated to reflect technology advances. System schematics, design assumptions, manufacturing assumptions, and cost results are presented.

  6. Organic/inorganic electrochromic nanocomposites with various interfacial interactions: A review

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Shanxin, E-mail: xiongsx@xust.edu.cn; Yin, Siyuan; Wang, Yuyun; Kong, Zhenzhen; Lan, Jinpeng; Zhang, Runlan; Gong, Ming; Wu, Bohua; Chu, Jia; Wang, Xiaoqin

    2017-07-15

    Highlights: • We review the effects of interfacial interactions in electrochromic nanocomposites. • Interfacial interactions are useful for film fabrication and property-enhancement. • The strong interaction can enhance the electron conduction and structural strength. • The weak interactions exist widely between organic and inorganic phases. • Multiple weak interactions can provide various performance-adjusting approaches. - Abstract: Electrochromic properties of organic or inorganic materials can be improved through preparing organic/inorganic electrochromic nanocomposites. In electrochromic nanocomposites, the interfacial interactions between the organic and inorganic phases play three important roles in preparation and application of the nanocomposites. Firstly, the interfacial interactions result in stable molecular structures. Secondly, they also improve the electron conduction and ion transport process in the nanocomposites. Thirdly, they enhance the electrochemical and electrochromic properties of the nanocomposites. In this paper, we review the common interfacial interactions including covalent bond, coordination bond, electrostatic interaction, hydrogen bond and π-π stacking interaction between the organic and inorganic phases in the electrochromic nanocomposites. The preparation method, the relationship between the structure and properties, and the mechanism of modulation of electrochromic effect in the nanocomposites with various interfacial interactions are surveyed. The strong interfacial interaction, e.g., covalent bond, is helpful for obtaining electrochromic nanocomposites with high electron conduction and high structural strength. However it is very complicated to construct covalent bond between the organic and inorganic phases. Another strong interfacial interaction, the coordination bond is mainly confined to preparation of electrochromic complex of metal ion and pyridine derivative. While, the weak interfacial interactions, e

  7. Organic/inorganic electrochromic nanocomposites with various interfacial interactions: A review

    International Nuclear Information System (INIS)

    Xiong, Shanxin; Yin, Siyuan; Wang, Yuyun; Kong, Zhenzhen; Lan, Jinpeng; Zhang, Runlan; Gong, Ming; Wu, Bohua; Chu, Jia; Wang, Xiaoqin

    2017-01-01

    Highlights: • We review the effects of interfacial interactions in electrochromic nanocomposites. • Interfacial interactions are useful for film fabrication and property-enhancement. • The strong interaction can enhance the electron conduction and structural strength. • The weak interactions exist widely between organic and inorganic phases. • Multiple weak interactions can provide various performance-adjusting approaches. - Abstract: Electrochromic properties of organic or inorganic materials can be improved through preparing organic/inorganic electrochromic nanocomposites. In electrochromic nanocomposites, the interfacial interactions between the organic and inorganic phases play three important roles in preparation and application of the nanocomposites. Firstly, the interfacial interactions result in stable molecular structures. Secondly, they also improve the electron conduction and ion transport process in the nanocomposites. Thirdly, they enhance the electrochemical and electrochromic properties of the nanocomposites. In this paper, we review the common interfacial interactions including covalent bond, coordination bond, electrostatic interaction, hydrogen bond and π-π stacking interaction between the organic and inorganic phases in the electrochromic nanocomposites. The preparation method, the relationship between the structure and properties, and the mechanism of modulation of electrochromic effect in the nanocomposites with various interfacial interactions are surveyed. The strong interfacial interaction, e.g., covalent bond, is helpful for obtaining electrochromic nanocomposites with high electron conduction and high structural strength. However it is very complicated to construct covalent bond between the organic and inorganic phases. Another strong interfacial interaction, the coordination bond is mainly confined to preparation of electrochromic complex of metal ion and pyridine derivative. While, the weak interfacial interactions, e

  8. Transportation

    International Nuclear Information System (INIS)

    Anon.

    1998-01-01

    Here is the decree of the thirtieth of July 1998 relative to road transportation, to trade and brokerage of wastes. It requires to firms which carry out a road transportation as well as to traders and to brokers of wastes to declare their operations to the prefect. The declaration has to be renewed every five years. (O.M.)

  9. Monitoring mass transport in heterogeneously catalyzed reactions by field-gradient NMR for assessing reaction efficiency in a single pellet

    Science.gov (United States)

    Buljubasich, L.; Blümich, B.; Stapf, S.

    2011-09-01

    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 H 2O 2.

  10. A new method to estimate global mass transport and its implication for sea level rise

    Science.gov (United States)

    Yi, S.; Heki, K.

    2017-12-01

    Estimates of changes in global land mass by using GRACE observations can be achieved by two methods, a mascon method and a forward modeling method. However, results from these two methods show inconsistent secular trend. Sea level budget can be adopted to validate the consistency among observations of sea level rise by altimetry, steric change by the Argo project, and mass change by GRACE. Mascon products from JPL, GSFC and CSR are compared here, we find that all these three products cannot achieve a reconciled sea level budget, while this problem can be solved by a new forward modeling method. We further investigate the origin of this difference, and speculate that it is caused by the signal leakage from the ocean mass. Generally, it is well recognized that land signals leak into oceans, but it also happens the other way around. We stress the importance of correction of leakage from the ocean in the estimation of global land masses. Based on a reconciled sea level budget, we confirmed that global sea level rise has been accelerating significantly over 2005-2015, as a result of the ongoing global temperature increase.

  11. Investigation of silicate surface chemistry and reaction mechanisms associated with mass transport in geologic media

    International Nuclear Information System (INIS)

    White, A.F.; Perry, D.L.

    1982-01-01

    The concentration and rate of transport of radionuclides through geologic media can be strongly influenced by the extent of sorption on aquifer surfaces. Over time intervals relevant to such transport processes, rock and mineral surfaces cannot be considered as inert, unreactive substrates but rather as groundwater/solidphase interfaces which are commonly in a state of natural or artificially induced disequilibrium. The goal of the present research is to define experimentally the type of water/rock interactions that will influence surface chemistry and hence sorption characteristics and capacities of natural aquifers. As wide a range of silicate minerals as possible was selected for study to represent rock-forming minerals in basalt, tuff, and granite. The minerals include K-feldspar, plagioclase feldspar, olivine, hornblende, biotite, and volcanic glass

  12. A desk study of surface diffusion and mass transport in clay

    International Nuclear Information System (INIS)

    Cook, A.J.

    1988-09-01

    The concept of a geological barrier to radionuclide migration from theoretical radioactive waste repositories has drawn attention to the physico-chemical properties of clays, which are traditionally regarded as retarding media. This report addresses the different mechanisms of transport of radionuclides through clay and in particular focuses on the surface diffusion movement of sorbed cations. The relative contributory importance of the different transport mechanisms is governed by the pore size distributions and interconnections within the clay fabric. Surface diffusion data in the literature have been from experiments using compacted montmorillonite and biotite gneiss. A possible programme of laboratory work is outlined, based on diffusion experiments, which describes the way of measuring the effect of surface diffusion more accurately in clays, mudstones and shales. (author)

  13. Mass and Momentum Transport in Microcavities for Diffusion-Dominant Cell Culture Applications

    Science.gov (United States)

    Yew, Alvin G.; Pinero, Daniel; Hsieh, Adam H.; Atencia, Javier

    2012-01-01

    For the informed design of microfluidic devices, it is important to understand transport phenomena at the microscale. This letter outlines an analytically-driven approach to the design of rectangular microcavities extending perpendicular to a perfusion microchannel for microfluidic cell culture devices. We present equations to estimate the spatial transition from advection- to diffusion-dominant transport inside cavities as a function of the geometry and flow conditions. We also estimate the time required for molecules, such as nutrients or drugs to travel from the microchannel to a given depth into the cavity. These analytical predictions can facilitate the rational design of microfluidic devices to optimize and maintain long-term, physiologically-based culture conditions with low fluid shear stress.

  14. Relationships of dispersive mass transport and stochastic convective flow through hydrologic systems

    International Nuclear Information System (INIS)

    Simmons, C.S.

    1981-01-01

    Uncertainty in water flow velocity appears to be a major factor in determining the magnitude of contaminant dispersion expected in a ground water system. This report discusses some concepts and mathematical methods relating dispersive contaminant transport to stochastic aspects of ground water flow. The theory developed should not be construed as absolutely rigorous mathematics, but is presented with the intention of clarifying the physical concepts

  15. Optimal-mass-transfer-based estimation of glymphatic transport in living brain

    OpenAIRE

    Ratner, Vadim; Zhu, Liangjia; Kolesov, Ivan; Nedergaard, Maiken; Benveniste, Helene; Tannenbaum, Allen

    2015-01-01

    It was recently shown that the brain-wide cerebrospinal fluid (CSF) and interstitial fluid exchange system designated the ‘glymphatic pathway’ plays a key role in removing waste products from the brain, similarly to the lymphatic system in other body organs1,2. It is therefore important to study the flow patterns of glymphatic transport through the live brain in order to better understand its functionality in normal and pathological states. Unlike blood, the CSF does not flow rapidly through ...

  16. Cerebrospinal Fluid and Interstitial Fluid Motion via the Glymphatic Pathway Modelled by Optimal Mass Transport

    OpenAIRE

    Benveniste, Helene; Nedergaard, Maikan; Lee, Hedok; Gao, Yi; Tannenbaum, Allen; Ratner, Vadim

    2016-01-01

    It was recently shown that the brain-wide cerebrospinal fluid (CSF) and interstitial fluid exchange system designated the `glymphatic pathway' plays a key role in removing waste products from the brain, similarly to the lymphatic system in other body organs [1,2]. It is therefore important to study the flow patterns of glymphatic transport through the live brain in order to better understand its functionality in normal and pathological states. Unlike blood, the CSF does not flow rapidly throu...

  17. Exceptional Air Mass Transport and Dynamical Drivers of an Extreme Wintertime Arctic Warm Event

    Science.gov (United States)

    Binder, Hanin; Boettcher, Maxi; Grams, Christian M.; Joos, Hanna; Pfahl, Stephan; Wernli, Heini

    2017-12-01

    At the turn of the years 2015/2016, maximum surface temperature in the Arctic reached record-high values, exceeding the melting point, which led to a strong reduction of the Arctic sea ice extent in the middle of the cold season. Here we show, using a Lagrangian method, that a combination of very different airstreams contributed to this event: (i) warm low-level air of subtropical origin, (ii) initially cold low-level air of polar origin heated by surface fluxes, and (iii) strongly descending air heated by adiabatic compression. The poleward transport of these warm airstreams occurred along an intense low-level jet between a series of cyclones and a quasi-stationary anticyclone. The complex 3-D configuration that enabled this transport was facilitated by continuous warm conveyor belt ascent into the upper part of the anticyclone. This study emphasizes the combined role of multiple transport processes and transient synoptic-scale dynamics for establishing an extreme Arctic warm event.

  18. Protein interfacial structure and nanotoxicology

    International Nuclear Information System (INIS)

    White, John W.; Perriman, Adam W.; McGillivray, Duncan J.; Lin, J.-M.

    2009-01-01

    Here we briefly recapitulate the use of X-ray and neutron reflectometry at the air-water interface to find protein structures and thermodynamics at interfaces and test a possibility for understanding those interactions between nanoparticles and proteins which lead to nanoparticle toxicology through entry into living cells. Stable monomolecular protein films have been made at the air-water interface and, with a specially designed vessel, the substrate changed from that which the air-water interfacial film was deposited. This procedure allows interactions, both chemical and physical, between introduced species and the monomolecular film to be studied by reflectometry. The method is briefly illustrated here with some new results on protein-protein interaction between β-casein and κ-casein at the air-water interface using X-rays. These two proteins are an essential component of the structure of milk. In the experiments reported, specific and directional interactions appear to cause different interfacial structures if first, a β-casein monolayer is attacked by a κ-casein solution compared to the reverse. The additional contrast associated with neutrons will be an advantage here. We then show the first results of experiments on the interaction of a β-casein monolayer with a nanoparticle titanium oxide sol, foreshadowing the study of the nanoparticle 'corona' thought to be important for nanoparticle-cell wall penetration.

  19. Protein interfacial structure and nanotoxicology

    Energy Technology Data Exchange (ETDEWEB)

    White, John W. [Research School of Chemistry, Australian National University, Canberra (Australia)], E-mail: jww@rsc.anu.edu.au; Perriman, Adam W.; McGillivray, Duncan J.; Lin, J.-M. [Research School of Chemistry, Australian National University, Canberra (Australia)

    2009-02-21

    Here we briefly recapitulate the use of X-ray and neutron reflectometry at the air-water interface to find protein structures and thermodynamics at interfaces and test a possibility for understanding those interactions between nanoparticles and proteins which lead to nanoparticle toxicology through entry into living cells. Stable monomolecular protein films have been made at the air-water interface and, with a specially designed vessel, the substrate changed from that which the air-water interfacial film was deposited. This procedure allows interactions, both chemical and physical, between introduced species and the monomolecular film to be studied by reflectometry. The method is briefly illustrated here with some new results on protein-protein interaction between {beta}-casein and {kappa}-casein at the air-water interface using X-rays. These two proteins are an essential component of the structure of milk. In the experiments reported, specific and directional interactions appear to cause different interfacial structures if first, a {beta}-casein monolayer is attacked by a {kappa}-casein solution compared to the reverse. The additional contrast associated with neutrons will be an advantage here. We then show the first results of experiments on the interaction of a {beta}-casein monolayer with a nanoparticle titanium oxide sol, foreshadowing the study of the nanoparticle 'corona' thought to be important for nanoparticle-cell wall penetration.

  20. Transportation

    National Research Council Canada - National Science Library

    Allshouse, Michael; Armstrong, Frederick Henry; Burns, Stephen; Courts, Michael; Denn, Douglas; Fortunato, Paul; Gettings, Daniel; Hansen, David; Hoffman, D. W; Jones, Robert

    2007-01-01

    .... The ability of the global transportation industry to rapidly move passengers and products from one corner of the globe to another continues to amaze even those wise to the dynamics of such operations...

  1. Mathematical model of vertical mass transport in the mine dumps Western Donbass

    Directory of Open Access Journals (Sweden)

    Yevhrashkina T.P.

    2012-09-01

    Full Text Available The multivariate mathematical models of the recultivated, recultivated and dumping with dry system, recultivated in systematically irrigation conditions and free of overgrowth by wild plants are proposed, designed and quantified. The theory of physico-chemical hydrodynamics of pore space using analytical and numerical methods for solving the equations of motion and mass conservation of matter all models are based on. The adequacy of built models and man-maid processes that proceed inside the mine dumps is proved.

  2. Location-dependent coronary artery diffusive and convective mass transport properties of a lipophilic drug surrogate measured using nonlinear microscopy.

    Science.gov (United States)

    Keyes, Joseph T; Simon, Bruce R; Vande Geest, Jonathan P

    2013-04-01

    Arterial wall mass transport properties dictate local distribution of biomolecules or locally delivered dugs. Knowing how these properties vary between coronary artery locations could provide insight into how therapy efficacy is altered between arterial locations. We introduced an indocarbocyanine drug surrogate to the lumens of left anterior descending and right coronary (LADC; RC) arteries from pigs with or without a pressure gradient. Interstitial fluorescent intensity was measured on live samples with multiphoton microscopy. We also measured binding to porcine coronary SMCs in monoculture. Diffusive transport constants peaked in the middle sections of the LADC and RC arteries by 2.09 and 2.04 times, respectively, compared to the proximal and distal segments. There was no statistical difference between the average diffusivity value between LADC and RC arteries. The convection coefficients had an upward trend down each artery, with the RC being higher than the LADC by 3.89 times. This study demonstrates that the convective and diffusive transport of lipophilic molecules changes between the LADC and the RC arteries as well as along their length. These results may have important implications in optimizing drug delivery for the treatment of coronary artery disease.

  3. Winter and summer monsoon water mass, heat and freshwater transport changes in the Arabian Sea near 8°N

    Science.gov (United States)

    Stramma, Lothar; Brandt, Peter; Schott, Friedrich; Quadfasel, Detlef; Fischer, Jürgen

    The differences in the water mass distributions and transports in the Arabian Sea between the summer monsoon of August 1993 and the winter monsoon of January 1998 are investigated, based on two hydrographic sections along approximately 8°N. At the western end the sections were closed by a northward leg towards the African continent at about 55°E. In the central basin along 8°N the monsoon anomalies of the temperature and density below the surface-mixed layer were dominated by annual Rossby waves propagating westward across the Arabian Sea. In the northwestern part of the basin the annual Rossby waves have much smaller impact, and the density anomalies observed there were mostly associated with the Socotra Gyre. Salinity and oxygen differences along the section reflect local processes such as the spreading of water masses originating in the Bay of Bengal, northward transport of Indian Central Water, or slightly stronger southward spreading of Red Sea Water in August than in January. The anomalous wind conditions of 1997/98 influenced only the upper 50-100 m with warmer surface waters in January 1998, and Bay of Bengal Water covered the surface layer of the section in the eastern Arabian Sea. Estimates of the overturning circulation of the Arabian Sea were carried out despite the fact that many uncertainties are involved. For both cruises a vertical overturning cell of about 4-6 Sv was determined, with inflow below 2500 m and outflow between about 300 and 2500 m. In the upper 300-450 m a seasonally reversing shallow meridional overturning cell appears to exist in which the Ekman transport is balanced by a geostrophic transport. The heat flux across 8°N is dominated by the Ekman transport, yielding about -0.6 PW for August 1993, and 0.24 PW for January 1998. These values are comparable to climatological and model derived heat flux estimates. Freshwater fluxes across 8°N also were computed, yielding northward freshwater fluxes of 0.07 Sv in January 1998 and 0

  4. Numerical simulation of heat and mass transport during hydration of Portland cement mortar in semi-adiabatic and steam curing conditions

    OpenAIRE

    Hernandez-Bautista, E.; Bentz, D. P.; Sandoval-Torres, S.; de Cano-Barrita, P. F. J.

    2016-01-01

    A model that describes hydration and heat-mass transport in Portland cement mortar during steam curing was developed. The hydration reactions are described by a maturity function that uses the equivalent age concept, coupled to a heat and mass balance. The thermal conductivity and specific heat of mortar with water-to-cement mass ratio of 0.30 was measured during hydration, using the Transient Plane Source method. The parameters for the maturity equation and the activation energy were obtaine...

  5. Handbook of heat and mass transfer. Volume 2

    International Nuclear Information System (INIS)

    Cheremisinoff, N.P.

    1986-01-01

    This two-volume series, the work of more than 100 contributors, presents advanced topics in industrial heat and mass transfer operations and reactor design technology. Volume 2 emphasizes mass transfer and reactor design. Some of the contents discussed are: MASS TRANSFER PRINCIPLES - Effect of turbulence promoters on mass transfer. Mass transfer principles with homogeneous and heterogeneous reactions. Convective diffusion with reactions in a tube. Transient mass transfer onto small particles and drops. Modeling heat and mass transport in falling liquid films. Heat and mass transfer in film absorption. Multicomponent mass transfer: theory and applications. Diffusion limitation for reaction in porous catalysts. Kinetics and mechanisms of catalytic deactivation. DISTILLATION AND EXTRACTION - Generalized equations of state for process design. Mixture boiling. Estimating vapor pressure from normal boiling points of hydrocarbons. Estimating liquid and vapor molar fractions in distillation columns. Principles of multicomponent distillation. Generalized design methods for multicomponent distillation. Interfacial films in inorganic substances extraction. Liquid-liquid extraction in suspended slugs. MULTIPHASE REACTOR SYSTEMS - Reaction and mass transport in two-phase reactors. Mass transfer and kinetics in three-phase reactors. Estimating liquid film mass transfer coefficients in randomly packed columns. Designing packed tower wet scrubbers - emphasis on nitrogen oxides. Gas absorption in aerated mixers. Axial dispersion and heat transfer in gas-liquid bubble columns. Operation and design of trickle-bed reactors

  6. Columnar aerosol optical and radiative properties according to season and air mass transport pattern over East Asia.

    Science.gov (United States)

    Noh, Young M; Müller, Detlef; Lee, Hanlim; Lee, Kwonho; Kim, Young Joon

    2012-08-01

    The column-integrated optical and radiative properties of aerosols in the downwind area of East Asia were investigated based on sun/sky radiometer measurements performed from February 2004 to June 2005 at Gwangju (35.23° N, 126.84° E) and Anmyeon (36.54° N, 126.33° E), Korea. The observed aerosol data were analyzed for differences among three seasons: spring (March-May), summer (June-August), and autumn/winter (September-February). The data were also categorized into five types depending on the air mass origin in arriving in the measurement sites: (a) from a northerly direction in spring (S(N)), (b) from a westerly direction in spring (S(W)), (c) cases with a low Ångström exponent (air mass origin. The forcing efficiency in summer was -131.7 and -125.6 W m(-2) at the surface in Gwangju and Anmyeon, respectively. These values are lower than those under the atmospheric conditions of spring and autumn/winter. The highest forcing efficiencies in autumn/winter were -214.3 and -255.9 W m(-2) at the surface in Gwangju and Anmyeon, respectively, when the air mass was transported from westerly directions.

  7. Earth System Data Records of Mass Transport from Time-Variable Gravity Data

    Science.gov (United States)

    Zlotnicki, V.; Talpe, M.; Nerem, R. S.; Landerer, F. W.; Watkins, M. M.

    2014-12-01

    Satellite measurements of time variable gravity have revolutionized the study of Earth, by measuring the ice losses of Greenland, Antarctica and land glaciers, changes in groundwater including unsustainable losses due to extraction of groundwater, the mass and currents of the oceans and their redistribution during El Niño events, among other findings. Satellite measurements of gravity have been made primarily by four techniques: satellite tracking from land stations using either lasers or Doppler radio systems, satellite positioning by GNSS/GPS, satellite to satellite tracking over distances of a few hundred km using microwaves, and through a gravity gradiometer (radar altimeters also measure the gravity field, but over the oceans only). We discuss the challenges in the measurement of gravity by different instruments, especially time-variable gravity. A special concern is how to bridge a possible gap in time between the end of life of the current GRACE satellite pair, launched in 2002, and a future GRACE Follow-On pair to be launched in 2017. One challenge in combining data from different measurement systems consists of their different spatial and temporal resolutions and the different ways in which they alias short time scale signals. Typically satellite measurements of gravity are expressed in spherical harmonic coefficients (although expansions in terms of 'mascons', the masses of small spherical caps, has certain advantages). Taking advantage of correlations among spherical harmonic coefficients described by empirical orthogonal functions and derived from GRACE data it is possible to localize the otherwise coarse spatial resolution of the laser and Doppler derived gravity models. This presentation discusses the issues facing a climate data record of time variable mass flux using these different data sources, including its validation.

  8. Biomimetic Interfacial Electron-Induced Electrochemiluminesence.

    Science.gov (United States)

    Pu, Guiqiang; Zhang, Dongxu; Mao, Xiang; Zhang, Zhen; Wang, Huan; Ning, Xingming; Lu, Xiaoquan

    2018-04-17

    We provide here, for the first time, a new interfacial electron-induced electrochemiluminescence (IEIECL) system, realizing bionic construction of bioluminescence (BL) by exploiting electrochemiluminescence (ECL) and ITIES (the interface between two immiscible electrolyte solutions). Significantly, the superiority of the IEIECL system is embodied with the solution of the two bottlenecks encountered in the conventional ECL innovation: that are (a) the applications of hydrophobic luminophores in more commonly used aqueous solution are inhibited tremendously due to the poor inherent solubility and the instability of radicals and (b) the analytes, insoluble in water, are hard to be discovered in an aqueous system because of too little content. More productive IEIECL radiation, analogous to BL, originates from the triplet excited state porphyrin in comparison to the homogeneous ECL. The mechanism of IEIECL, as well as the interaction mechanism between IEIECL and charge transfer (comprising electron transfer (ET), ion transfer (IT), and facilitated ion transfer (FIT)) at the ITIES, are explored in detail. Finally, we emphasize the actual application potential of the IEIECL system with the detection of cytochrome c (Cyt c); it is a key biomolecule in the electron transport chain in the process of biological oxidation and is also an intermediate species in apoptosis. Potentially, the IEIECL system permits ones to explore the lifetime and diffusion path of free radicals, as well as imparting a possibility for the construction of a bionic sensor.

  9. The Transport of Mass, Energy, and Entropy in Cryogenic Support Struts for Engineering Design

    Science.gov (United States)

    Elchert, J. P.

    2012-01-01

    Engineers working to understand and reduce cryogenic boil-off must solve a variety of transport problems. An important class of nonlinear problems involves the thermal and mechanical design of cryogenic struts. These classic problems are scattered about the literature and typically require too many resources to obtain. So, to save time for practicing engineers, the author presents this essay. Herein, a variety of new, old, and revisited analytical and finite difference solutions of the thermal problem are covered in this essay, along with commentary on approach and assumptions. This includes a few thermal radiation and conduction combined mode solutions with a discussion on insulation, optimum emissivity, and geometrical phenomenon. Solutions to cooling and heat interception problems are also presented, including a discussion of the entropy generation. The literature on the combined mechanical and thermal design of cryogenic support struts is reviewed with an introduction to the associated numerical methods.

  10. Atomistic simulations of bulk, surface and interfacial polymer properties

    Science.gov (United States)

    Natarajan, Upendra

    In chapter I, quasi-static molecular mechanics based simulations are used to estimate the activation energy of phenoxy rings flips in the amorphous region of a semicrystalline polyimide. Intra and intermolecular contributions to the flip activation energy, the torsional cooperativity accompanying the flip, and the effect of the flip on the motion in the glassy bulk state, are looked at. Also, comparison of the weighted mean activation energy is made with experimental data from solid state NMR measurements; the simulated value being 17.5 kcal/mol., while the experimental value was observed to be 10.5 kcal/mol. Chapter II deals with construction of random copolymer thin films of styrene-butadiene (SB) and styrene-butadiene-acrylonitrile (SBA). The structure and properties of the free surfaces presented by these thin films are analysed by, the atom mass density profiles, backbone bond orientation function, and the spatial distribution of acrylonitrile groups and styrene rings. The surface energies of SB and SBA are calculated using an atomistic equation and are compared with experimental data in the literature. In chapter III, simulations of polymer-polymer interfaces between like and unlike polymers, specifically cis-polybutadiene (PBD) and atatic polypropylene (PP), are presented. The structure of an incompatible polymer-polymer interface, and the estimation of the thermodynamic work of adhesion and interfacial energy between different incompatible polymers, form the focus here. The work of adhesion is calculated using an atomistic equation and is further used in a macroscopic equation to estimate the interfacial energy. The interfacial energy is compared with typical values for other immiscible systems in the literature. The interfacial energy compared very well with interfacial energy values for a few other immiscible hydrocarbon pairs. In chapter IV, the study proceeds to look at the interactions between nonpolar and polar small molecules with SB and SBA thin

  11. An arbitrary Lagrangian-Eulerian method for interfacial flows with insoluble surfactants

    Science.gov (United States)

    Yang, Xiaofeng

    Interfacial flows, fluid flows involving two or more fluids that do not mix, are common in many natural and industrial processes such as rain drop formation, crude oil recovery, polymer blending, fuel spray formation, and so on. Surfactants (surface active substances) play an important role in such processes because they significantly change the interfacial dynamics. In this thesis, an arbitrary Lagrangian-Eulerian (ALE) method has been developed to numerically simulate interfacial flows with insoluble surfactants. The interface is captured using a coupled level set and volume of fluid method. To evolve the surfactant concentration, the method directly tracks the surfactant mass and the interfacial area. The surfactant concentration, which determines the local surface tension through an equation of state, is then computed as surfactant mass per interfacial area. By directly tracking the surfactant mass, the method conserves the surfactant mass exactly. To accurately approximate the interfacial area, the fluid interface is reconstructed using piecewise parabolas. The evolution of the level set function, volume fraction, interfacial area, and the surfactant mass is performed using an ALE approach. The fluid flow is governed by Stokes equations, which are solved using a finite element method. The surface forces are included in the momentum equation using a continuum surface stress formulation. To efficiently resolve the complex interfacial dynamics, interfacial regions of high surface curvature, and near contact regions between two interacting interfaces, the grid near the interface is adaptively refined. The method is extendible to axisymmetric and 3D spaces, and can be coupled with other flow solvers, such as Navier-Stokes and viscoelastic flow solvers, as well. The method has been applied to study the effect of surfactants on drop deformation and breakup in an extensional flow. Drop deformation results are compared with available experimental and theoretical

  12. Re-assessing Present Day Global Mass Transport and Glacial Isostatic Adjustment From a Data Driven Approach

    Science.gov (United States)

    Wu, X.; Jiang, Y.; Simonsen, S.; van den Broeke, M. R.; Ligtenberg, S.; Kuipers Munneke, P.; van der Wal, W.; Vermeersen, B. L. A.

    2017-12-01

    Determining present-day mass transport (PDMT) is complicated by the fact that most observations contain signals from both present day ice melting and Glacial Isostatic Adjustment (GIA). Despite decades of progress in geodynamic modeling and new observations, significant uncertainties remain in both. The key to separate present-day ice mass change and signals from GIA is to include data of different physical characteristics. We designed an approach to separate PDMT and GIA signatures by estimating them simultaneously using globally distributed interdisciplinary data with distinct physical information and a dynamically constructed a priori GIA model. We conducted a high-resolution global reappraisal of present-day ice mass balance with focus on Earth's polar regions and its contribution to global sea-level rise using a combination of ICESat, GRACE gravity, surface geodetic velocity data, and an ocean bottom pressure model. Adding ice altimetry supplies critically needed dual data types over the interiors of ice covered regions to enhance separation of PDMT and GIA signatures, and achieve half an order of magnitude expected higher accuracies for GIA and consequently ice mass balance estimates. The global data based approach can adequately address issues of PDMT and GIA induced geocenter motion and long-wavelength signatures important for large areas such as Antarctica and global mean sea level. In conjunction with the dense altimetry data, we solved for PDMT coefficients up to degree and order 180 by using a higher-resolution GRACE data set, and a high-resolution a priori PDMT model that includes detailed geographic boundaries. The high-resolution approach solves the problem of multiple resolutions in various data types, greatly reduces aliased errors from a low-degree truncation, and at the same time, enhances separation of signatures from adjacent regions such as Greenland and Canadian Arctic territories.

  13. Nanofluidic transport over a curved surface with viscous dissipation and convective mass flux

    Energy Technology Data Exchange (ETDEWEB)

    Mehmood, Zaffar; Iqbal, Z.; Azhar, Ehtsham; Maraj, E.N. [HITEC Univ., Taxila (Pakistan). Dept. of Mathematics

    2017-06-01

    This article is a numerical investigation of boundary layer flow of nanofluid over a bended stretching surface. The study is carried out by considering convective mass flux condition. Contribution of viscous dissipation is taken into the account along with thermal radiation. Suitable similarity transformations are employed to simplify the system of nonlinear partial differential equations into a system of nonlinear ordinary differential equations. Computational results are extracted by means of a shooting method embedded with a Runge-Kutta Fehlberg technique. Key findings include that velocity is a decreasing function of curvature parameter K. Moreover, Nusselt number decreases with increase in curvature of the stretching surface while skin friction and Sherwood number enhance with increase in K.

  14. Global stability and exact solution of an arbitrary-solute nonlinear cellular mass transport system.

    Science.gov (United States)

    Benson, James D

    2014-12-01

    The prediction of the cellular state as a function of extracellular concentrations and temperatures has been of interest to physiologists for nearly a century. One of the most widely used models in the field is one where mass flux is linearly proportional to the concentration difference across the membrane. These fluxes define a nonlinear differential equation system for the intracellular state, which when coupled with appropriate initial conditions, define the intracellular state as a function of the extracellular concentrations of both permeating and nonpermeating solutes. Here we take advantage of a reparametrization scheme to extend existing stability results to a more general setting and to a develop analytical solutions to this model for an arbitrary number of extracellular solutes. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Physical models of mass transport of iron and nickel in liquid sodium systems

    International Nuclear Information System (INIS)

    Davies, B.S.J.; Polley, M.V.; Skyrme, G.

    1975-12-01

    Experimental observations on corrosion of pure iron and nickel specimens in non-isothermal loops containing flowing sodium have been used to derive values of the concentration of dissolved material at the entrance to the test section and diffusion coefficients of the test material in sodium. The former values differ from the saturation value by only 10 -3 ppm, which is small compared to currently recommended solubility values. The phenomenon cannot be explained in terms of circulating particles. Two other possible explanations are also dismissed. The diffusion coefficient values are consistent with the corroding species being atoms, or molecules containing a few atoms. It is also shown that the observations are better explained in terms of boundary layer controlled mass transfer, rather than a surface controlled process. A computer model based on an alternative solubility relationship is shown to produce results which describe well the observed variation of corrosion rate with oxygen concentration, sodium velocity and downstream position. (author)

  16. POROUS MICROSTRUCTURE OF THE INTERFACIAL TRANSITION ZONE IN GEOPOLYMER COMPOSITES

    Directory of Open Access Journals (Sweden)

    Steinerová M.

    2013-12-01

    Full Text Available The study deals with a comparison of the differences in the structure, composition and micromechanical properties of a metakaolinite geopolymer composite matrix, inside and outside of the interfacial transition zone (ITZ with quartz grains of added silica sand. The microstructure is investigated by a measurement of the mercury porosimetry, microscopy and by a measurement in SEM and AFM, completed by Raman spectroscopy. Weaker mechanical properties, micropores in the ITZ, a higher concentration of Al atoms and hydroxyl groups than in the ambient matrix were detected. The water transport is probably the reason for the micropore formation, caused by disequilibrium in the course of solid-phase building from geopolymer dispersion.

  17. Confined methane-water interfacial layers and thickness measurements using in situ Raman spectroscopy.

    Science.gov (United States)

    Pinho, Bruno; Liu, Yukun; Rizkin, Benjamin; Hartman, Ryan L

    2017-11-07

    Gas-liquid interfaces broadly impact our planet, yet confined interfaces behave differently than unconfined ones. We report the role of tangential fluid motion in confined methane-water interfaces. The interfaces are created using microfluidics and investigated by in situ 1D, 2D and 3D Raman spectroscopy. The apparent CH 4 and H 2 O concentrations are reported for Reynolds numbers (Re), ranging from 0.17 to 8.55. Remarkably, the interfaces are comprised of distinct layers of thicknesses varying from 23 to 57 μm. We found that rarefaction, mixture, thin film, and shockwave layers together form the interfaces. The results indicate that the mixture layer thickness (δ) increases with Re (δ ∝ Re), and traditional transport theory for unconfined interfaces does not explain the confined interfaces. A comparison of our results with thin film theory of air-water interfaces (from mass transfer experiments in capillary microfluidics) supports that the hydrophobicity of CH 4 could decrease the strength of water-water interactions, resulting in larger interfacial thicknesses. Our findings help explain molecular transport in confined gas-liquid interfaces, which are common in a broad range of societal applications.

  18. Aerosol Particle Interfacial Thermodynamics and Phase Partitioning Measurements Using Biphasic Microfluidics

    Science.gov (United States)

    Dutcher, Cari; Metcalf, Andrew

    2015-03-01

    Secondary organic aerosol particles are nearly ubiquitous in the atmosphere and yet there remain large uncertainties in their formation processes and ambient properties. These particles are complex microenvironments, which can contain multiple interfaces due to internal aqueous-organic phase partitioning and to the external liquid-vapor surface. Interfacial properties affect the ambient aerosol morphology, or internal structure of the particle, which in turn can affect the way a particle interacts with an environment of condensable clusters and organic vapors. To improve our ability to accurately predict ambient aerosol morphology, we must improve our knowledge of aerosol interfaces and their interactions with the ambient environment. Unfortunately, many techniques employed to measure interfacial properties do so in bulk solutions or in the presence of a ternary (e.g. solid) phase. In this talk, a novel method using biphasic microscale flows will be introduced for generating, trapping, and perturbing complex interfaces at atmospherically relevant conditions. These microfluidic experiments utilize high-speed imaging to monitor interfacial phenomena at the microscale and are performed with phase contrast and fluorescence microscopy on a temperature-controlled inverted microscope stage. From these experiments, interfacial thermodynamic properties such as surface or interfacial tension, rheological properties such as interfacial moduli, and kinetic properties such as mass transfer coefficients can be measured or inferred.

  19. Evaluation of mass transport property using natural uranium-series and thorium-series nuclides in the Toki Granite

    International Nuclear Information System (INIS)

    Hama, Katsuhiro

    2016-07-01

    The Mizunami Underground Research Laboratory (MIU) project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host crystalline rock at Mizunami City in Gifu Prefecture, central Japan. The project proceeds in three overlapping phases, 'Phase I: Surface-based investigation Phase', 'Phase II: Construction Phase' and 'Phase III: Operation Phase'. As a part of the Phase III investigation, the mass transport property has been evaluated by using natural uranium-series and thorium-series nuclides in the Toki Granite. In this report, the compilation of existing data and preliminary evaluation was carried out. (author)

  20. Mass transport at rotating disk electrodes: effects of synthetic particles and nerve endings.

    Science.gov (United States)

    Chiu, Veronica M; Lukus, Peter A; Doyle, Jamie L; Schenk, James O

    2011-11-01

    An unstirred layer (USL) exists at the interface of solids with solutions. Thus, the particles in brain tissue preparations possess a USL as well as at the surface of a rotating disk electrode (RDE) used to measure chemical fluxes. Time constraints for observing biological kinetics based on estimated thicknesses of USLs at the membrane surface in real samples of nerve endings were estimated. Liposomes, silica, and Sephadex were used separately to model the tissue preparation particles. Within a solution stirred by the RDE, both diffusion and hydrodynamic boundary layers are formed. It was observed that the number and size of particles decreased the following: the apparent diffusion coefficient excluding Sephadex, boundary layer thicknesses excluding silica, sensitivity excluding diluted liposomes (in agreement with results from other laboratories), limiting current potentially due to an increase in the path distance, and mixing time. They have no effect on the detection limit (6 ± 2 nM). The RDE kinetically resolves transmembrane transport with a timing of approximately 30 ms. Copyright © 2011 Elsevier Inc. All rights reserved.

  1. Factors that affect mass transport from drug eluting stents into the artery wall

    Directory of Open Access Journals (Sweden)

    Walsh Michael T

    2010-03-01

    Full Text Available Abstract Coronary artery disease can be treated by implanting a stent into the blocked region of an artery, thus enabling blood perfusion to distal vessels. Minimally invasive procedures of this nature often result in damage to the arterial tissue culminating in the re-blocking of the vessel. In an effort to alleviate this phenomenon, known as restenosis, drug eluting stents were developed. They are similar in composition to a bare metal stent but encompass a coating with therapeutic agents designed to reduce the overly aggressive healing response that contributes to restenosis. There are many variables that can influence the effectiveness of these therapeutic drugs being transported from the stent coating to and within the artery wall, many of which have been analysed and documented by researchers. However, the physical deformation of the artery substructure due to stent expansion, and its influence on a drugs ability to diffuse evenly within the artery wall have been lacking in published work to date. The paper highlights previous approaches adopted by researchers and proposes the addition of porous artery wall deformation to increase model accuracy.

  2. Water injection into vapor- and liquid-dominated reservoirs: Modeling of heat transfer and mass transport

    Energy Technology Data Exchange (ETDEWEB)

    Pruess, K.; Oldenburg, C.; Moridis, G.; Finsterle, S. [Lawrence Berkeley National Lab., CA (United States)

    1997-12-31

    This paper summarizes recent advances in methods for simulating water and tracer injection, and presents illustrative applications to liquid- and vapor-dominated geothermal reservoirs. High-resolution simulations of water injection into heterogeneous, vertical fractures in superheated vapor zones were performed. Injected water was found to move in dendritic patterns, and to experience stronger lateral flow effects than predicted from homogeneous medium models. Higher-order differencing methods were applied to modeling water and tracer injection into liquid-dominated systems. Conventional upstream weighting techniques were shown to be adequate for predicting the migration of thermal fronts, while higher-order methods give far better accuracy for tracer transport. A new fluid property module for the TOUGH2 simulator is described which allows a more accurate description of geofluids, and includes mineral dissolution and precipitation effects with associated porosity and permeability change. Comparisons between numerical simulation predictions and data for laboratory and field injection experiments are summarized. Enhanced simulation capabilities include a new linear solver package for TOUGH2, and inverse modeling techniques for automatic history matching and optimization.

  3. Quantification of segregation and mass transport in InxGa1-xASGaAs Stranski-Krastanow layers

    International Nuclear Information System (INIS)

    Rosenauer, A.; Gerthsen, D.; Van Dyck, D.; Arzberger, M.; Boehm, G.; Abstreiter, G.

    2001-01-01

    We report on transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy measurement of mass transport and segregation in InAs Stranski-Krastanow layers grown on GaAs(001) by molecular beam epitaxy at growth temperatures of 480 and 530 deg. C. Plan-view TEM reveals regularly shaped islands with a density of 7.8x10 10 cm -2 (480 deg. C) and 1.5x10 10 cm -2 (530 deg. C), respectively. Uncapped islands were investigated by strain state analysis of electron wave functions reconstructed from high-resolution TEM images. In-concentration profiles of the islands were obtained by the measurement of lattice-parameter profiles of the islands and the application of finite-element calculations. We find that the islands contain Ga-atoms with a percentage of 50% (480 deg. C) and 67% (530 deg. C). The capped InAs-layers were investigated with PL and TEM. In agreement with TEM, PL indicates a smaller and deeper potential well of the islands grown at 480 deg. C. Concentration profiles of the wetting layers were measured with TEM using the composition evaluation of lattice fringe images method, clearly revealing segregation profiles. The obtained segregation efficiency of In-atoms is 0.77±0.02 (480 deg. C) and 0.82±0.02 (530 deg. C). As an explanation for the strong mass transport of Ga from the substrate to the islands we show that the segregation of In atoms during the growth of the binary InAs can lead to the generation of vacancies in the metal sublattice. The vacancies are filled by Ga-atoms migrating along the surface or by a diffusion of the vacancies from the wetting layer and the islands into the GaAs buffer, leading to a unidirectional diffusion of Ga atoms from the buffer into the Stranski-Krastanow layer

  4. Mass transport and the bootstrap current from Ohm's law in steady-state tokamaks

    International Nuclear Information System (INIS)

    Kim, J.-S.; Greene, J.M.

    1989-01-01

    The consequences of mass conservation and Ohm's law are examined for steady state Tokamaks. In a Tokamak, magnetofluid-dynamic waves rapidly equilibrate pressure and toroidal field along magnetic surfaces. As a result, the detailed current distribution is determined by the flux surface averaged poloidal and toroidal currents. The electrons that carry the plasma current are impeded in their motion by interactions with ions, which is resistivity and its generalizations, and by interactions with electrons, which is viscosity and its generalizations. The important viscous terms arise from the interaction between trapped and untrapped electrons, and so viscosity acts by impeding poloidal current. properly chosen, the results of neoclassical theory are The neoclassical viscous coefficient is here regarded as less likely than Spitzer conductivity to be experimentally relevant in a turbulent Tokamak. Thus, the toroidal Ohm's law is regarded as being more reliable than the poloidal Ohm's law. A combination of toroidal and poloidal Ohm's law, namely the component parallel to the magnetic field, eliminates the influence of plasma fueling, and directly relates the bootstrap current and the pressure gradient. The latter is the usual relation, but, since i

  5. Transportation

    Science.gov (United States)

    2007-01-01

    Faculty ii INDUSTRY TRAVEL Domestic Assistant Deputy Under Secretary of Defense (Transportation Policy), Washington, DC Department of...developed between the railroad and trucking industries. Railroads: Today’s seven Class I freight railroad systems move 42% of the nation’s intercity ...has been successfully employed in London to reduce congestion and observed by this industry study during its travels . It is currently being

  6. Quantum statistical effects in the mass transport of interstitial solutes in a crystalline solid

    Science.gov (United States)

    Woo, C. H.; Wen, Haohua

    2017-09-01

    The impact of quantum statistics on the many-body dynamics of a crystalline solid at finite temperatures containing an interstitial solute atom (ISA) is investigated. The Mori-Zwanzig theory allows the many-body dynamics of the crystal to be formulated and solved analytically within a pseudo-one-particle approach using the Langevin equation with a quantum fluctuation-dissipation relation (FDR) based on the Debye model. At the same time, the many-body dynamics is also directly solved numerically via the molecular dynamics approach with a Langevin heat bath based on the quantum FDR. Both the analytical and numerical results consistently show that below the Debye temperature of the host lattice, quantum statistics significantly impacts the ISA transport properties, resulting in major departures from both the Arrhenius law of diffusion and the Einstein-Smoluchowski relation between the mobility and diffusivity. Indeed, we found that below one-third of the Debye temperature, effects of vibrations on the quantum mobility and diffusivity are both orders-of-magnitude larger and practically temperature independent. We have shown that both effects have their physical origin in the athermal lattice vibrations derived from the phonon ground state. The foregoing theory is tested in quantum molecular dynamics calculation of mobility and diffusivity of interstitial helium in bcc W. In this case, the Arrhenius law is only valid in a narrow range between ˜300 and ˜700 K. The diffusivity becomes temperature independent on the low-temperature side while increasing linearly with temperature on the high-temperature side.

  7. Spectroscopic imaging studies of nanoscale polarity and mass transport phenomena in self-assembled organic nanotubes.

    Science.gov (United States)

    Xu, Hao; Nagasaka, Shinobu; Kameta, Naohiro; Masuda, Mitsutoshi; Ito, Takashi; Higgins, Daniel A

    2017-08-02

    Synthetic organic nanotubes self-assembled from bolaamphiphile surfactants are now being explored for use as drug delivery vehicles. In this work, several factors important to their implementation in drug delivery are explored. All experiments are performed with the nanotubes immersed in ethanol. First, Nile Red (NR) and a hydroxylated Nile Red derivative (NR-OH) are loaded into the nanotubes and spectroscopic fluorescence imaging methods are used to determine the apparent dielectric constant of their local environment. Both are found in relatively nonpolar environments, with the NR-OH molecules preferring regions of relatively higher dielectric constant compared to NR. Unique two-color imaging fluorescence correlation spectroscopy (imaging FCS) measurements are then used along with the spectroscopic imaging results to deduce the dielectric properties of the environments sensed by mobile and immobile populations of probe molecules. The results reveal that mobile NR molecules pass through less polar regions, likely within the nanotube walls, while immobile NR molecules are found in more polar regions, possibly near the nanotube surfaces. In contrast, mobile and immobile NR-OH molecules are found to locate in environments of similar polarity. The imaging FCS results also provide quantitative data on the apparent diffusion coefficient for each dye. The mean diffusion coefficient for the NR dye was approximately two-fold larger than that of NR-OH. Slower diffusion by the latter could result from its additional hydrogen bonding interactions with polar triglycine, amine, and glucose moieties near the nanotube surfaces. The knowledge gained in these studies will allow for the development of nanotubes that are better engineered for applications in the controlled transport and release of uncharged, dipolar drug molecules.

  8. Effects of surface roughening on the mass transport and mechanical properties of ionic polymer-metal composite

    Science.gov (United States)

    Chang, Longfei; Asaka, Kinji; Zhu, Zicai; Wang, Yanjie; Chen, Hualing; Li, Dichen

    2014-06-01

    Ionic Polymer-Metal Composite (IPMC) has been well-documented of being a promising functional material in extensive applications. In its most popular and traditional manufacturing technique, roughening is a key process to ensure a satisfying performance. In this paper, based on a lately established multi-physical model, the effect of roughening process on the inner mass transportation and the electro-active output of IPMC were investigated. In the model, the electro-chemical field was monitored by Poisson equation and a properly simplified Nernst-Planck equation set, while the mechanical field was evaluated on the basis of volume strain effect. Furthermore, with Ramo-Shockley theorem, the out-circuit current and accumulated charge on the electrode were bridged with the inner cation distribution. Besides, nominal current and charge density as well as the curvature of the deformation were evaluated to characterize the performance of IPMC. The simulation was implemented by Finite Element Method with Comsol Multi-physics, based on two groups of geometrical models, those with various rough interface and those with different thickness. The results of how the roughening impact influences on the performance of IPMC were discussed progressively in three aspects, steady-state distribution of local potential and mass concentration, current response and charge accumulation, as well as the curvature of deformation. Detailed explanations for the performance improvement resulted from surface roughening were provided from the micro-distribution point of view, which can be further explored for the process optimization of IPMC.

  9. The Role of Rotation in Convective Heat Transport: an Application to Low-Mass Stars

    Science.gov (United States)

    Matilsky, Loren; Hindman, Bradley W.; Toomre, Juri; Featherstone, Nicholas

    2018-06-01

    It is often supposed that the convection zones (CZs) of low-mass stars are purely adiabatically stratified. This is thought to be because convective motions are extremely efficient at homogenizing entropy within the CZ. For a purely adiabatic fluid layer, only very small temperature variations are required to drive convection, making the amplitude and overall character of the convection highly sensitive to the degree of adiabaticity established in the CZ. The presence of rotation, however, fundamentally changes the dynamics of the CZ; the strong downflow plumes that are required to homogenize entropy are unable to penetrate through the entire fluid layer if they are deflected too soon by the Coriolis force. This talk discusses 3D global models of spherical-shell convection subject to different rotation rates. The simulation results emphasize the possibility that for stars with a high enough rotation rate, large fractions of their CZs are not in fact adiabatically stratified; rather, there is a finite superadiabatic gradient that varies in magnitude with radius, being at a minimum in the CZ’s middle layers. Two consequences of the varying superadiabatic gradient are that the convective amplitudes at the largest length scales are effectively suppressed and that there is a strong latitudinal temperature gradient from a cold equator to a hot pole, which self-consistently drives a thermal wind. A connection is naturally drawn to the Sun’s CZ, which has supergranulation as an upper limit to its convective length scales and isorotational contours along radial lines, which can be explained by the presence of a thermal wind.

  10. Mechanisms of material removal and mass transport in focused ion beam nanopore formation

    Energy Technology Data Exchange (ETDEWEB)

    Das, Kallol, E-mail: das7@illinois.edu; Johnson, Harley T., E-mail: htj@illinois.edu [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 West Green Street, MC-244, Urbana, Illinois 61801 (United States); Freund, Jonathan B., E-mail: jbfreund@illinois.edu [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 West Green Street, MC-244, Urbana, Illinois 61801 (United States); Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, 306 Talbot Laboratory, MC-236, 104 South Wright Street Urbana, Illinois 61801 (United States)

    2015-02-28

    Despite the widespread use of focused ion beam (FIB) processing as a material removal method for applications ranging from electron microscope sample preparation to nanopore processing for DNA sequencing, the basic material removal mechanisms of FIB processing are not well understood. We present the first complete atomistic simulation of high-flux FIB using large-scale parallel molecular dynamics (MD) simulations of nanopore fabrication in freestanding thin films. We focus on the root mechanisms of material removal and rearrangement and describe the role of explosive boiling in forming nanopores. FIB nanopore fabrication is typically understood to occur via sputter erosion. This can be shown to be the case in low flux systems, where individual ion impacts are sufficiently separated in time that they may be considered as independent events. But our detailed MD simulations show that in high flux FIB processing, above a threshold level at which thermal effects become significant, the primary mechanism of material removal changes to a significantly accelerated, thermally dominated process. Under these conditions, the target is heated by the ion beam faster than heat is conducted away by the material, leading quickly to melting, and then continued heating to nearly the material critical temperature. This leads to explosive boiling of the target material with spontaneous bubble formation and coalescence. Mass is rapidly rearranged at the atomistic scale, and material removal occurs orders of magnitude faster than would occur by simple sputtering. While the phenomenology is demonstrated computationally in silicon, it can be expected to occur at lower beam fluxes in other cases where thermal conduction is suppressed due to material properties, geometry, or ambient thermal conditions.

  11. Determinants of black carbon, particle mass and number concentrations in London transport microenvironments

    Science.gov (United States)

    Rivas, Ioar; Kumar, Prashant; Hagen-Zanker, Alex; Andrade, Maria de Fatima; Slovic, Anne Dorothee; Pritchard, John P.; Geurs, Karst T.

    2017-07-01

    We investigated the determinants of personal exposure concentrations of commuters' to black carbon (BC), ultrafine particle number concentrations (PNC), and particulate matter (PM1, PM2.5 and PM10) in different travel modes. We quantified the contribution of key factors that explain the variation of the previous pollutants in four commuting routes in London, each covered by four transport modes (car, bus, walk and underground). Models were performed for each pollutant, separately to assess the effect of meteorology (wind speed) or ambient concentrations (with either high spatial or temporal resolution). Concentration variations were mainly explained by wind speed or ambient concentrations and to a lesser extent by route and period of the day. In multivariate models with wind speed, the wind speed was the common significant predictor for all the pollutants in the above-ground modes (i.e., car, bus, walk); and the only predictor variable for the PM fractions. Wind speed had the strongest effect on PM during the bus trips, with an increase in 1 m s-1 leading to a decrease in 2.25, 2.90 and 4.98 μg m-3 of PM1, PM2.5 and PM10, respectively. PM2.5 and PM10 concentrations in car trips were better explained by ambient concentrations with high temporal resolution although from a single monitoring station. On the other hand, ambient concentrations with high spatial coverage but lower temporal resolution predicted better the concentrations in bus trips, due to bus routes passing through streets with a high variability of traffic intensity. In the underground models, wind speed was not significant and line and type of windows on the train explained 42% of the variation of PNC and 90% of all PM fractions. Trains in the district line with openable windows had an increase in concentrations of 1 684 cm-3 for PNC and 40.69 μg m-3 for PM2.5 compared with trains that had non-openable windows. The results from this work can be used to target efforts to reduce personal exposures of

  12. Modeling of flow and mass transport processes in unsaturated soils in combination with technical facilities

    International Nuclear Information System (INIS)

    Hasan, Issa

    2014-01-01

    The modelling of complex systems such as the underground is a means to describe the processes occurring in the reality. The conducting of experiments on a model to obtain qualitative evidence about a real system is referred to as a simulation. Thereby, various models (e.g. physical and mathematical models) can be used. The unsaturated zone (vadose zone) is the region between the land surface and the water table, in which the water content is less than full saturation, and the pressure is lower than the atmospheric pressure. The unsaturated zone is very significant for agriculture, geobiology, aerobic degradation processes and groundwater recharge. The processes of water flow and solute transport in the unsaturated zone can be described by means of numerical simulation programs. The aim of the present work is a comprehensive validation of the simulation program PCSiWaPro registered (developed at the TU-Dresden, Institute of Waste Management and Contaminated Site Treatment) for different applications. Another aim of this work is to investigate the applicability of the current version of PCSiWaPro registered for different cases of a combination between the unsaturated zone and technical facilities. Four application cases with different objectives were investigated within the present work, which are: the simulation of decentralized wastewater infiltration with corresponding column and field experiments, the computation of groundwater recharge by means of lysimeters, the water balance of earth dams and the modelling of landfill covering systems. The application cases differ from each other by the objective of the simulation, the geometry, the size, the specified initial and boundary conditions, the simulation time, the applied materials, the coordinate system, the input and output data. The simulation results clearly showed that PCSiWaPro registered is applicable for all investigated cases under consideration of different flow and solute transport regimes, parameters

  13. Understanding Interfacial Alignment in Solution Coated Conjugated Polymer Thin Films

    International Nuclear Information System (INIS)

    Qu, Ge; Zhao, Xikang; Newbloom, Gregory M.; Zhang, Fengjiao; Mohammadi, Erfan

    2017-01-01

    Domain alignment in conjugated polymer thin films can significantly enhance charge carrier mobility. However, the alignment mechanism during meniscus-guided solution coating remains unclear. Furthermore, interfacial alignment has been rarely studied despite its direct relevance and critical importance to charge transport. In this study, we uncover a significantly higher degree of alignment at the top interface of solution coated thin films, using a donor–acceptor conjugated polymer, poly(diketopyrrolopyrrole-co-thiopheneco- thieno[3,2-b]thiophene-co-thiophene) (DPP2T-TT), as the model system. At the molecular level, we observe in-plane π–π stacking anisotropy of up to 4.8 near the top interface with the polymer backbone aligned parallel to the coating direction. The bulk of the film is only weakly aligned with the backbone oriented transverse to coating. At the mesoscale, we observe a well-defined fibril-like morphology at the top interface with the fibril long axis pointing toward the coating direction. Significantly smaller fibrils with poor orientational order are found on the bottom interface, weakly aligned orthogonal to the fibrils on the top interface. The high degree of alignment at the top interface leads to a charge transport anisotropy of up to 5.4 compared to an anisotropy close to 1 on the bottom interface. We attribute the formation of distinct interfacial morphology to the skin-layer formation associated with high Peclet number, which promotes crystallization on the top interface while suppressing it in the bulk. As a result, we further infer that the interfacial fibril alignment is driven by the extensional flow on the top interface arisen from increasing solvent evaporation rate closer to the meniscus front.

  14. Computing optimal interfacial structure of modulated phases

    OpenAIRE

    Xu, Jie; Wang, Chu; Shi, An-Chang; Zhang, Pingwen

    2016-01-01

    We propose a general framework of computing interfacial structures between two modulated phases. Specifically we propose to use a computational box consisting of two half spaces, each occupied by a modulated phase with given position and orientation. The boundary conditions and basis functions are chosen to be commensurate with the bulk structures. It is observed that the ordered nature of modulated structures stabilizes the interface, which enables us to obtain optimal interfacial structures...

  15. Modeling interfacial fracture in Sierra.

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Arthur A.; Ohashi, Yuki; Lu, Wei-Yang; Nelson, Stacy A. C.; Foulk, James W.,; Reedy, Earl David,; Austin, Kevin N.; Margolis, Stephen B.

    2013-09-01

    This report summarizes computational efforts to model interfacial fracture using cohesive zone models in the SIERRA/SolidMechanics (SIERRA/SM) finite element code. Cohesive surface elements were used to model crack initiation and propagation along predefined paths. Mesh convergence was observed with SIERRA/SM for numerous geometries. As the funding for this project came from the Advanced Simulation and Computing Verification and Validation (ASC V&V) focus area, considerable effort was spent performing verification and validation. Code verification was performed to compare code predictions to analytical solutions for simple three-element simulations as well as a higher-fidelity simulation of a double-cantilever beam. Parameter identification was conducted with Dakota using experimental results on asymmetric double-cantilever beam (ADCB) and end-notched-flexure (ENF) experiments conducted under Campaign-6 funding. Discretization convergence studies were also performed with respect to mesh size and time step and an optimization study was completed for mode II delamination using the ENF geometry. Throughout this verification process, numerous SIERRA/SM bugs were found and reported, all of which have been fixed, leading to over a 10-fold increase in convergence rates. Finally, mixed-mode flexure experiments were performed for validation. One of the unexplained issues encountered was material property variability for ostensibly the same composite material. Since the variability is not fully understood, it is difficult to accurately assess uncertainty when performing predictions.

  16. Multiscale Modeling of Mesoscale and Interfacial Phenomena

    Science.gov (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

  17. Robotic transport complex of automotive vehicles for handling of rock mass at the process of open cast mining

    Directory of Open Access Journals (Sweden)

    Anatoly KOLGA

    2015-06-01

    Full Text Available The article is concerned with the applicability of the robotic transportation complex of automotive barrows for haulage transportation along various transport routes of mining enterprises. The simultaneous application of robotic transport and telemetry links makes the door-to-door transportation possible, i.e. direct transportation from the starting to the final point avoiding intermediate storage and a considerable part of auxiliary equipment.

  18. Effect of Atmospheric Ions on Interfacial Water

    Directory of Open Access Journals (Sweden)

    Chien-Chang Kurt Kung

    2014-11-01

    Full Text Available The effect of atmospheric positivity on the electrical properties of interfacial water was explored. Interfacial, or exclusion zone (EZ water was created in the standard way, next to a sheet of Nafion placed horizontally at the bottom of a water-filled chamber. Positive atmospheric ions were created from a high voltage source placed above the chamber. Electrical potential distribution in the interfacial water was measured using microelectrodes. We found that beyond a threshold, the positive ions diminished the magnitude of the negative electrical potential in the interfacial water, sometimes even turning it to positive. Additionally, positive ions produced by an air conditioner were observed to generate similar effects; i.e., the electrical potential shifted in the positive direction but returned to negative when the air conditioner stopped blowing. Sometimes, the effect of the positive ions from the air conditioner was strong enough to destroy the structure of interfacial water by turning the potential decidedly positive. Thus, positive air ions can compromise interfacial water negativity and may explain the known negative impact of positive ions on health.

  19. TFB:TPDSi2 interfacial layer usable in organic photovoltaic cells

    Science.gov (United States)

    Marks, Iobin J [Evanston, IL; Hains, Alexander W [Evanston, IL

    2011-02-15

    The present invention, in one aspect, relates to a solar cell. In one embodiment, the solar cell includes an anode; an active organic layer comprising an electron-donating organic material and an electron-accepting organic material; and an interfacial layer formed between the anode and active organic layer, where the interfacial layer comprises a hole-transporting polymer characterized with a hole-mobility higher than that of the electron-donating organic material in the active organic layer, and a small molecule that has a high hole-mobility and is capable of crosslinking on contact with air.

  20. The Interfacial Transition Zone in Alkali-Activated Slag Mortars

    Directory of Open Access Journals (Sweden)

    Rackel eSan Nicolas

    2015-12-01

    Full Text Available The interfacial transition zone (ITZ is known to strongly influence the mechanical and transport properties of mortars and concretes. This paper studies the ITZ between siliceous (quartz aggregates and alkali activated slag binders in the context of mortar specimens. Backscattered electron images (BSE generated in an environmental scanning electron microscope (ESEM are used to identify unreacted binder components, reaction products and porosity in the zone surrounding aggregate particles, by composition and density contrast. X-ray mapping is used to exclude the regions corresponding to the aggregates from the BSE image of the ITZ, thus enabling analysis of only the binder phases, which are segmented into binary images by grey level discrimination. A distinct yet dense ITZ region is present in the alkali-activated slag mortars, containing a reduced content of unreacted slag particles compared to the bulk binder. The elemental analysis of this region shows that it contains a (C,N-A-S-H gel which seems to have a higher content of Na (potentially deposited through desiccation of the pore solution and a lower content of Ca than the bulk inner and outer products forming in the main binding region. These differences are potentially important in terms of long-term concrete performance, as the absence of a highly porous interfacial transition zone region is expected to provide a positive influence on the mechanical and transport properties of alkali-activated slag concretes.

  1. Interfacial reactions in thermoelectric modules

    KAUST Repository

    Wu, Hsin-jay; Wu, Albert T.; Wei, Pei-chun; Chen, Sinn-wen

    2018-01-01

    Engineering transport properties of thermoelectric (TE) materials leads to incessantly breakthroughs in the zT values. Nevertheless, modular design holds a key factor to advance the TE technology. Herein, we discuss the structures of TE module

  2. Additively manufactured metallic porous biomaterials based on minimal surfaces: A unique combination of topological, mechanical, and mass transport properties.

    Science.gov (United States)

    Bobbert, F S L; Lietaert, K; Eftekhari, A A; Pouran, B; Ahmadi, S M; Weinans, H; Zadpoor, A A

    2017-04-15

    Porous biomaterials that simultaneously mimic the topological, mechanical, and mass transport properties of bone are in great demand but are rarely found in the literature. In this study, we rationally designed and additively manufactured (AM) porous metallic biomaterials based on four different types of triply periodic minimal surfaces (TPMS) that mimic the properties of bone to an unprecedented level of multi-physics detail. Sixteen different types of porous biomaterials were rationally designed and fabricated using selective laser melting (SLM) from a titanium alloy (Ti-6Al-4V). The topology, quasi-static mechanical properties, fatigue resistance, and permeability of the developed biomaterials were then characterized. In terms of topology, the biomaterials resembled the morphological properties of trabecular bone including mean surface curvatures close to zero. The biomaterials showed a favorable but rare combination of relatively low elastic properties in the range of those observed for trabecular bone and high yield strengths exceeding those reported for cortical bone. This combination allows for simultaneously avoiding stress shielding, while providing ample mechanical support for bone tissue regeneration and osseointegration. Furthermore, as opposed to other AM porous biomaterials developed to date for which the fatigue endurance limit has been found to be ≈20% of their yield (or plateau) stress, some of the biomaterials developed in the current study show extremely high fatigue resistance with endurance limits up to 60% of their yield stress. It was also found that the permeability values measured for the developed biomaterials were in the range of values reported for trabecular bone. In summary, the developed porous metallic biomaterials based on TPMS mimic the topological, mechanical, and physical properties of trabecular bone to a great degree. These properties make them potential candidates to be applied as parts of orthopedic implants and/or as bone

  3. Mass balance and isotope effects during nitrogen transport through septic tank systems with packed-bed (sand) filters

    Science.gov (United States)

    Hinkle, S.R.; Böhlke, J.K.; Fisher, L.H.

    2008-01-01

    Septic tank systems are an important source of NO3- to many aquifers, yet characterization of N mass balance and isotope systematics following septic tank effluent discharge into unsaturated sediments has received limited attention. In this study, samples of septic tank effluent before and after transport through single-pass packed-bed filters (sand filters) were evaluated to elucidate mass balance and isotope effects associated with septic tank effluent discharge to unsaturated sediments. Chemical and isotopic data from five newly installed pairs and ten established pairs of septic tanks and packed-bed filters serving single homes in Oregon indicate that aqueous solute concentrations are affected by variations in recharge (precipitation, evapotranspiration), NH4+ sorption (primarily in immature systems), nitrification, and gaseous N loss via NH3 volatilization and(or) N2 or N2O release during nitrification/denitrification. Substantial NH4+ sorption capacity was also observed in laboratory columns with synthetic effluent. Septic tank effluent ??15N-NH4+ values were almost constant and averaged + 4.9??? ?? 0.4??? (1 ??). In contrast, ??15N values of NO3- leaving mature packed-bed filters were variable (+ 0.8 to + 14.4???) and averaged + 7.2??? ?? 2.6???. Net N loss in the two networks of packed-bed filters was indicated by average 10-30% decreases in Cl--normalized N concentrations and 2-3??? increases in ??15N, consistent with fractionation accompanying gaseous N losses and corroborating established links between septic tank effluent and NO3- in a local, shallow aquifer. Values of ??18O-NO3- leaving mature packed-bed filters ranged from - 10.2 to - 2.3??? (mean - 6.4??? ?? 1.8???), and were intermediate between a 2/3 H2O-O + 1/3 O2-O conceptualization and a 100% H2O-O conceptualization of ??18O-NO3- generation during nitrification.

  4. Interfacial interactions and mass transfer at the interfacial region of bituminous hydrocarbon mixtures

    NARCIS (Netherlands)

    Van Lent, D.Q.

    2014-01-01

    The adhesion between bitumen and aggregate is a complex process with numerous of variables. To improve the understanding of the bond between bitumen and aggregates in road applications, this research focuses on preferential adsorption, which is one aspect of bitumen-aggregate adhesion. The main

  5. Interfacial functionalization and engineering of nanoparticles

    Science.gov (United States)

    Song, Yang

    The intense research interest in nanoscience and nanotechnology is largely fueled by the unique properties of nanoscale materials. In this dissertation, the research efforts are focused on surface functionalization and interfacial engineering of functional nanoparticles in the preparation of patchy nanoparticles (e.g., Janus nanoparticles and Neapolitan nanoparticles) such that the nanoparticle structures and properties may be manipulated to an unprecedented level of sophistication. Experimentally, Janus nanoparticles were prepared by an interfacial engineering method where one hemisphere of the originally hydrophobic nanoparticles was replaced with hydrophilic ligands at the air|liquid or solid|liquid interface. The amphiphilic surface characters of the Janus nanoparticles were verified by contact angle measurements, as compared to those of the bulk-exchange counterparts where the two types of ligands were distributed rather homogeneously on the nanoparticle surface. In a further study, a mercapto derivative of diacetylene was used as the hydrophilic ligands to prepare Janus nanoparticles by using hydrophobic hexanethiolate-protected gold nanoparticles as the starting materials. Exposure to UV irradiation led to effective covalent cross-linking between the diacetylene moieties of neighboring ligands and hence marked enhancement of the structural integrity of the Janus nanoparticles, which was attributable to the impeded surface diffusion of the thiol ligands on the nanoparticle surface, as manifested in fluorescence measurements of aged nanoparticles. More complicated bimetallic AgAu Janus nanoparticles were prepared by interfacial galvanic exchange reactions of a Langmuir-Blodgett monolayer of 1-hexanethiolate-passivated silver nanoparticles on a glass slide with gold(I)-mercaptopropanediol complex in a water/ethanol solution. The resulting nanoparticles exhibited an asymmetrical distribution not only of the organic capping ligands on the nanoparticle surface but

  6. What Controls Thermo-osmosis? Molecular Simulations Show the Critical Role of Interfacial Hydrodynamics

    Science.gov (United States)

    Fu, Li; Merabia, Samy; Joly, Laurent

    2017-11-01

    Thermo-osmotic and related thermophoretic phenomena can be found in many situations from biology to colloid science, but the underlying molecular mechanisms remain largely unexplored. Using molecular dynamics simulations, we measure the thermo-osmosis coefficient by both mechanocaloric and thermo-osmotic routes, for different solid-liquid interfacial energies. The simulations reveal, in particular, the crucial role of nanoscale interfacial hydrodynamics. For nonwetting surfaces, thermo-osmotic transport is largely amplified by hydrodynamic slip at the interface. For wetting surfaces, the position of the hydrodynamic shear plane plays a key role in determining the amplitude and sign of the thermo-osmosis coefficient. Finally, we measure a giant thermo-osmotic response of the water-graphene interface, which we relate to the very low interfacial friction displayed by this system. These results open new perspectives for the design of efficient functional interfaces for, e.g., waste-heat harvesting.

  7. What Controls Thermo-osmosis? Molecular Simulations Show the Critical Role of Interfacial Hydrodynamics.

    Science.gov (United States)

    Fu, Li; Merabia, Samy; Joly, Laurent

    2017-11-24

    Thermo-osmotic and related thermophoretic phenomena can be found in many situations from biology to colloid science, but the underlying molecular mechanisms remain largely unexplored. Using molecular dynamics simulations, we measure the thermo-osmosis coefficient by both mechanocaloric and thermo-osmotic routes, for different solid-liquid interfacial energies. The simulations reveal, in particular, the crucial role of nanoscale interfacial hydrodynamics. For nonwetting surfaces, thermo-osmotic transport is largely amplified by hydrodynamic slip at the interface. For wetting surfaces, the position of the hydrodynamic shear plane plays a key role in determining the amplitude and sign of the thermo-osmosis coefficient. Finally, we measure a giant thermo-osmotic response of the water-graphene interface, which we relate to the very low interfacial friction displayed by this system. These results open new perspectives for the design of efficient functional interfaces for, e.g., waste-heat harvesting.

  8. Interfacial structures of confined air-water two-phase bubbly flow

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S.; Ishii, M.; Wu, Q.; McCreary, D.; Beus, S.G.

    2000-08-01

    The interfacial structure of the two-phase flows is of great importance in view of theoretical modeling and practical applications. In the present study, the focus is made on obtaining detailed local two-phase parameters in the air-water bubbly flow in a rectangular vertical duct using the double-sensor conductivity probe. The characteristic wall-peak is observed in the profiles of the interracial area concentration and the void fraction. The development of the interfacial area concentration along the axial direction of the flow is studied in view of the interfacial area transport and bubble interactions. The experimental data is compared with the drift flux model with C{sub 0} = 1.35.

  9. Interfacial structures of confined air-water two-phase bubbly flow

    International Nuclear Information System (INIS)

    Kim, S.; Ishii, M.; Wu, Q.; McCreary, D.; Beus, S.G.

    2000-01-01

    The interfacial structure of the two-phase flows is of great importance in view of theoretical modeling and practical applications. In the present study, the focus is made on obtaining detailed local two-phase parameters in the air-water bubbly flow in a rectangular vertical duct using the double-sensor conductivity probe. The characteristic wall-peak is observed in the profiles of the interracial area concentration and the void fraction. The development of the interfacial area concentration along the axial direction of the flow is studied in view of the interfacial area transport and bubble interactions. The experimental data is compared with the drift flux model with C 0 = 1.35

  10. The impact of the transient uptake flux on bioaccumulation : Linear adsorption and first-order internalisation coupled with spherical semi-infinite mass transport

    NARCIS (Netherlands)

    Galceran, J.; Monné, J.; Puy, J.; Leeuwen, van H.P.

    2004-01-01

    The uptake of a chemical species (such as an organic molecule or a toxic metal ion) by an organism is modelled considering linear pre-adsorption followed by a first-order internalisation. The active biosurface is supposed to be spherical or semi-spherical and the mass transport in the medium is

  11. The specchio unit (northern apennines, Italy): An ancient mass transport complex originated from near-coastal areas in an intra-slope setting

    NARCIS (Netherlands)

    Ogata, Kei; Tinterri, Roberto; Pini, Gian Andrea; Mutti, Emiliano

    2012-01-01

    Within the Eocene-Oligocene syn-orogenic deposits of the Epiligurian succession (Northern Apennines of Italy), a field-based study of the Specchio Unit (lower Rupelian) reveals that this complex is made up of three distinct but amalgamated mass-transport deposits (MTDs), the largest of which reaches

  12. Analysis of the contribution of sedimentation to bacterial mass transport in a parallel plate flow chamber Part II : Use of fluorescence imaging

    NARCIS (Netherlands)

    Li, Jiuyi; Busscher, Henk J.; van der Mei, Henny C.; Norde, Willem; Krom, Bastiaan P.; Sjollema, Jelmer

    2011-01-01

    Using a new phase-contrast microscopy-based method of analysis, sedimentation has recently been demonstrated to be the major mass transport mechanism of bacteria towards substratum surfaces in a parallel plate flow chamber (J. Li, H.J. Busscher, W. Norde, J. Sjollema, Colloid Surf. B. 84 (2011)76).

  13. Surface and interfacial chemistry of high-k dielectric and interconnect materials on silicon

    Science.gov (United States)

    Kirsch, Paul Daniel

    Surfaces and interfaces play a critical role in the manufacture and function of silicon based integrated circuits. It is therefore reasonable to study the chemistries at these surfaces and interfaces to improve existing processes and to develop new ones. Model barium strontium titanate high-k dielectric systems have been deposited on ultrathin silicon oxynitride in ultrahigh vacuum. The resulting nanostructures are characterized with secondary ion mass spectroscopy (SIMS) and X-ray photoelectron spectroscopy (XPS). An interfacial reaction between Ba and Sr atoms and SiOxNy was found to create silicates, BaSixOy or SrSi xOy. Inclusion of N in the interfacial oxide decreased silicate formation in both Ba and Sr systems. Furthermore, inclusion of N in the interfacial oxide decreased the penetration of Ba and Sr containing species, such as silicides and silicates. Sputter deposited HfO2 was studied on nitrided and unnitrided Si(100) surfaces. XPS and SIMS were used to verify the presence of interfacial HfSixOy and estimate its relative amount on both nitrided and unnitrided samples. More HfSixOy formed without the SiNx interfacial layer. These interfacial chemistry results are then used to explain the electrical measurements obtained from metal oxide semiconductor (MOS) capacitors. MOS capacitors with interfacial SiNx exhibit reduced leakage current and increased capacitance. Lastly, surface science techniques were used to develop a processing technique for reducing thin films of copper (II) and copper (I) oxide to copper. Deuterium atoms (D*) and methyl radicals (CH3*) were shown to reduce Cu 2+ and/or Cu1+ to Cu0 within 30 min at a surface temperature of 400 K under a flux of 1 x 1015 atoms/cm2s. Temperature programmed desorption experiments suggest that oxygen leaves the surface as D2O and CO2 for the D* and CH3* treated surfaces, respectively.

  14. Growth kinetics and mass transport mechanisms of GaN columns by selective area metal organic vapor phase epitaxy

    Science.gov (United States)

    Wang, Xue; Hartmann, Jana; Mandl, Martin; Sadat Mohajerani, Matin; Wehmann, Hergo-H.; Strassburg, Martin; Waag, Andreas

    2014-04-01

    Three-dimensional GaN columns recently have attracted a lot of attention as the potential basis for core-shell light emitting diodes for future solid state lighting. In this study, the fundamental insights into growth kinetics and mass transport mechanisms of N-polar GaN columns during selective area metal organic vapor phase epitaxy on patterned SiOx/sapphire templates are systematically investigated using various pitch of apertures, growth time, and silane flow. Species impingement fluxes on the top surface of columns Jtop and on their sidewall Jsw, as well as, the diffusion flux from the substrate Jsub contribute to the growth of the GaN columns. The vertical and lateral growth rates devoted by Jtop, Jsw and Jsub are estimated quantitatively. The diffusion length of species on the SiOx mask surface λsub as well as on the sidewall surfaces of the 3D columns λsw are determined. The influences of silane on the growth kinetics are discussed. A growth model is developed for this selective area metal organic vapor phase epitaxy processing.

  15. Thermal, chemical, and mass transport processes induced in abyssal sediments by the emplacement of nuclear wastes: Experimental and modelling results

    International Nuclear Information System (INIS)

    McVey, D.F.; Erickson, K.L.; Seyfried, W.E. Jr.

    1983-01-01

    In this chapter the authors discuss the current status of heat and mass transport studies in the marine red clay sediments that are being considered as a nuclear waste isolation medium and review analytical and experimental studies. Calculations based on numerical models indicate that for a maximum allowable sediment-canister interface temperatures of 200 0 to 250 0 C, the sediment can absorb about 1.5kW initial power from waste buried 30 m in the sediment in a canister that is 3 m long and 0.3 m in diameter. The resulting fluid displacement due to convections is found to be small, less than 1 m. Laboratory studies of the geochemical effects induced by heating sediment-seawater mixtures indicate that the canister and waste form should be designed to resist a hot, relatively acidic oxidizing environment. Since the thermally altered sediment volume of about 5.5 m/sup 3/ is small relative to the sediment volume overlying the canister, the acid and oxidizing conditions should significantly affect the properties of the far field only if thermodiffusional process (Soret effect) prove to be significant. If thermodiffusional effects are important, however, near-field chemistry will differ considerably from that predicted from results of constant temperature sediment-seawater interaction experiments

  16. Investigation of the shape change of bio-flocs and its influence on mass transport using particle image velocimetry.

    Science.gov (United States)

    Ren, T T; Xiao, F; Sun, W J; Sun, F Y; Lam, K M; Li, X Y

    2014-01-01

    In this laboratory study, an advanced flow visualization technique - particle image velocimetry (PIV) - was employed to investigate the change of shape of activated sludge flocs in water and its influence on the material transport characteristics of the flocs. The continuous shape change of the bio-flocs that occurred within a very short period of time could be captured by the PIV system. The results demonstrate that the fluid turbulence caused the shift of parts of a floc from one side to the other in less than 200 ms. During the continuous shape change, the liquid within the floc was forced out of the floc, which was then refilled with the liquid from the surrounding flow. For the bio-flocs saturated with a tracer dye, it was shown that the dye could be released from the flocs at a faster rate when the flocs were swayed around in water. The experimental results indicate that frequent shape change of bio-flocs facilitates the exchange of fluid and materials between the floc interior and the surrounding water. This mass transfer mechanism can be more important than molecular diffusion and internal permeation to the function and behavior of particle aggregates, including bio-flocs, in natural waters and treatment systems.

  17. Interfacial electron and phonon scattering processes in high-powered nanoscale applications.

    Energy Technology Data Exchange (ETDEWEB)

    Hopkins, Patrick E.

    2011-10-01

    The overarching goal of this Truman LDRD project was to explore mechanisms of thermal transport at interfaces of nanomaterials, specifically linking the thermal conductivity and thermal boundary conductance to the structures and geometries of interfaces and boundaries. Deposition, fabrication, and post possessing procedures of nanocomposites and devices can give rise to interatomic mixing around interfaces of materials leading to stresses and imperfections that could affect heat transfer. An understanding of the physics of energy carrier scattering processes and their response to interfacial disorder will elucidate the potentials of applying these novel materials to next-generation high powered nanodevices and energy conversion applications. An additional goal of this project was to use the knowledge gained from linking interfacial structure to thermal transport in order to develop avenues to control, or 'tune' the thermal transport in nanosystems.

  18. A solution-processed binary cathode interfacial layer facilitates electron extraction for inverted polymer solar cells.

    Science.gov (United States)

    Zhang, Xinyuan; Li, Zhiqi; Liu, Chunyu; Guo, Jiaxin; Shen, Liang; Guo, Wenbin

    2018-03-15

    The charge transfer and separation are significantly affected by the electron properties of the interface between the electron-donor layer and the carrier-transporting layer in polymer solar cells (PSCs). In this study, we investigate the electron extraction mechanism of PSCs with a low temperature solution-processed ZnO/PEI as electron transport layer. The incorporation of PEI layer can decrease the work function of ZnO and reduce interfacial barrier, which facilitates electron extraction and suppresses bimolecular recombination, leading to a significant performance enhancement. Furthermore, PEI layer can induce phase separation and passivite inorganic surface trap states as well as shift the interfacial energy offset between metal oxide and organic materials. This work offers a simple and effective way to improve the charge transporting property of organic photovoltaic devices. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Experimental study of interfacial shear stress for an analogy model of evaporative heat transfer

    International Nuclear Information System (INIS)

    Kwon, Hyuk; Park, GoonCherl; Min, ByungJoo

    2008-01-01

    In this study, we conducted measurements of an evaporative interfacial shear stress in a passive containment cooling system (PCCS). An interfacial shear stress for a counter-current flow was measured from a momentum balance equation and the interfacial friction factor for evaporation was evaluated by using experimental data. A model for the evaporative heat transfer coefficient of a vertical evaporative flat surface was developed based on an analogy between heat and momentum transfer. It was found that the interfacial shear stress increases with the Jacob number, which incorporates the evaporation rate, and the air and water Reynolds numbers. The relationship between the evaporative heat transfer and the interfacial shear stress was evaluated by using the experimental results. This relationship was used to develop a model for an evaporative heat transfer coefficient by using an analogy between heat and mass transfer. The prediction of this model were found to be in good agreement with the experimental data obtained for evaporative heat transfer by Kang and Park. (author)

  20. Strain-Mediated Interfacial Dynamics during Au–PbS Core–Shell Nanostructure Formation

    KAUST Repository

    Niu, Kai-Yang; Liu, Miao; Persson, Kristin A.; Han, Yu; Zheng, Haimei

    2016-01-01

    An understanding of the hierarchical nanostructure formation is of significant importance for the design of advanced functional materials. Here, we report the in situ study of lead sulfide (PbS) growth on gold (Au) nanorod seeds using liquid cell transmission electron microscopy (TEM). By tracking the formation dynamics of Au-PbS core-shell nanoparticles, we found the preferential heterogeneous nucleation of PbS on the ends of a Au nanorod prior to the development of a complete PdS shell. During PbS shell growth, drastic sulfidation of Au nanorod was observed, leading to large volume shrinkage (up to 50%) of the initial Au nanorod seed. We also captured intriguing wavy interfacial behavior, which can be explained by our DFT calculation results that the local strain gradient at the core-shell interface facilitates the mass transport and mediates reversible phase transitions of Au ↔ Au2S during the PbS shell growth. © 2016 American Chemical Society.

  1. Unravelling surface and interfacial structures of a metal-organic framework by transmission electron microscopy.

    Science.gov (United States)

    Zhu, Yihan; Ciston, Jim; Zheng, Bin; Miao, Xiaohe; Czarnik, Cory; Pan, Yichang; Sougrat, Rachid; Lai, Zhiping; Hsiung, Chia-En; Yao, Kexin; Pinnau, Ingo; Pan, Ming; Han, Yu

    2017-05-01

    Metal-organic frameworks (MOFs) are crystalline porous materials with designable topology, porosity and functionality, having promising applications in gas storage and separation, ion conduction and catalysis. It is challenging to observe MOFs with transmission electron microscopy (TEM) due to the extreme instability of MOFs upon electron beam irradiation. Here, we use a direct-detection electron-counting camera to acquire TEM images of the MOF ZIF-8 with an ultralow dose of 4.1 electrons per square ångström to retain the structural integrity. The obtained image involves structural information transferred up to 2.1 Å, allowing the resolution of individual atomic columns of Zn and organic linkers in the framework. Furthermore, TEM reveals important local structural features of ZIF-8 crystals that cannot be identified by diffraction techniques, including armchair-type surface terminations and coherent interfaces between assembled crystals. These observations allow us to understand how ZIF-8 crystals self-assemble and the subsequent influence of interfacial cavities on mass transport of guest molecules.

  2. Electrodeposition of enzymes-integrated mesoporous composite films by interfacial templating: A paradigm for electrochemical biosensors

    International Nuclear Information System (INIS)

    Wang, Dongming; Tan, Yiwei

    2014-01-01

    The development of nanostructured electrodes for electrochemical biosensors is of significant interest for modern detection, portable devices, and enhanced performance. However, development of such sensors still remains challenging due to the time-consuming, detriment-to-nature, and costly modifications of both electrodes and enzymes. In this work, we report a simple one-step approach to fabricating high-performance, direct electron transfer (DET) based nanoporous enzyme-embedded electrodes by electrodeposition coupled with recent progress in potential-controlled interfacial surfactant assemblies. In contrast to those previously electrodeposited mesoporous materials that are not bioactive, we imparted the biofunctionality to electrodeposited mesoporous thin films by means of the amphiphilic phospholipid templates strongly interacting with enzymes. Thus, phospholipid-templated mesoporous ZnO films covalently inlaid with the pristine enzymes were prepared by simple one-step electrodeposition. We further demonstrate two examples of such hybrid film electrodes embedded with alcohol dehydrogenase (ADH) and glucose oxidase (GOx), which are effectively employed as electrochemical biosensors for amperometric sensing of ethanol and glucose without using any electron relays. The favorable mass transport and large contact surface area provided by nanopores play an important role in improving the performance of these two biosensors, such as excellent sensitivities, low detection limits, and fast response. The matrix mesoporous films acting as effective electronic bridges are responsible for DET between enzyme molecules and metal electrode

  3. Strain-Mediated Interfacial Dynamics during Au–PbS Core–Shell Nanostructure Formation

    KAUST Repository

    Niu, Kai-Yang

    2016-05-23

    An understanding of the hierarchical nanostructure formation is of significant importance for the design of advanced functional materials. Here, we report the in situ study of lead sulfide (PbS) growth on gold (Au) nanorod seeds using liquid cell transmission electron microscopy (TEM). By tracking the formation dynamics of Au-PbS core-shell nanoparticles, we found the preferential heterogeneous nucleation of PbS on the ends of a Au nanorod prior to the development of a complete PdS shell. During PbS shell growth, drastic sulfidation of Au nanorod was observed, leading to large volume shrinkage (up to 50%) of the initial Au nanorod seed. We also captured intriguing wavy interfacial behavior, which can be explained by our DFT calculation results that the local strain gradient at the core-shell interface facilitates the mass transport and mediates reversible phase transitions of Au ↔ Au2S during the PbS shell growth. © 2016 American Chemical Society.

  4. Unravelling surface and interfacial structures of a metal–organic framework by transmission electron microscopy

    KAUST Repository

    Zhu, Yihan

    2017-02-21

    Metal–organic frameworks (MOFs) are crystalline porous materials with designable topology, porosity and functionality, having promising applications in gas storage and separation, ion conduction and catalysis1, 2, 3. It is challenging to observe MOFs with transmission electron microscopy (TEM) due to the extreme instability of MOFs upon electron beam irradiation4, 5, 6, 7. Here, we use a direct-detection electron-counting camera to acquire TEM images of the MOF ZIF-8 with an ultralow dose of 4.1 electrons per square ångström to retain the structural integrity. The obtained image involves structural information transferred up to 2.1 Å, allowing the resolution of individual atomic columns of Zn and organic linkers in the framework. Furthermore, TEM reveals important local structural features of ZIF-8 crystals that cannot be identified by diffraction techniques, including armchair-type surface terminations and coherent interfaces between assembled crystals. These observations allow us to understand how ZIF-8 crystals self-assemble and the subsequent influence of interfacial cavities on mass transport of guest molecules.

  5. Effects of Surface Treatment Processes of SiC Ceramic on Interfacial Bonding Property of SiC-AFRP

    Directory of Open Access Journals (Sweden)

    WEI Ru-bin

    2016-12-01

    Full Text Available To improve the interfacial bonding properties of SiC-aramid fiber reinforced polymer matrix composites (SiC-AFRP, the influences of etching process of SiC ceramic, coupling treatment process, and the adhesives types on the interfacial peel strength of SiC-AFRP were studied. The results show that the surface etching process and coupling treatment process of silicon carbide ceramic can effectively enhance interfacial bonding property of the SiC-AFRP. After soaked the ceramic in K3Fe(CN6 and KOH mixed etching solution for 2 hours, and coupled with vinyl triethoxy silane coupling agent, the interfacial peel strength of the SiC-AFRP significantly increases from 0.45kN/m to 2.20kN/m. EVA hot melt film with mass fraction of 15%VA is ideal for interface adhesive.

  6. Microfluidic ultralow interfacial tensiometry with magnetic particles.

    Science.gov (United States)

    Tsai, Scott S H; Wexler, Jason S; Wan, Jiandi; Stone, Howard A

    2013-01-07

    We describe a technique that measures ultralow interfacial tensions using paramagnetic spheres in a co-flow microfluidic device designed with a magnetic section. Our method involves tuning the distance between the co-flowing interface and the magnet's center, and observing the behavior of the spheres as they approach the liquid-liquid interface-the particles either pass through or are trapped by the interface. Using threshold values of the magnet-to-interface distance, we make estimates of the two-fluid interfacial tension. We demonstrate the effectiveness of this technique for measuring very low interfacial tensions, O(10(-6)-10(-5)) N m(-1), by testing solutions of different surfactant concentrations, and we show that our results are comparable with measurements made using a spinning drop tensiometer.

  7. Tunable anomalous hall effect induced by interfacial catalyst in perpendicular multilayers

    Science.gov (United States)

    Zhang, J. Y.; Peng, W. L.; Sun, Q. Y.; Liu, Y. W.; Dong, B. W.; Zheng, X. Q.; Yu, G. H.; Wang, C.; Zhao, Y. C.; Wang, S. G.

    2018-04-01

    The interfacial structures, playing a critical role on the transport properties and the perpendicular magnetic anisotropy in thin films and multilayers, can be modified by inserting an ultrathin functional layer at the various interfaces. The anomalous Hall effect (AHE) in the multilayers with core structure of Ta/CoFeB/X/MgO/Ta (X: Hf or Pt) is tuned by interfacial catalytic engineering. The saturation anomalous Hall resistance (RAH) is increased by 16.5% with 0.1 nm Hf insertion compared with the reference sample without insertion. However, the RAH value is decreased by 9.0% with 0.1 nm Pt insertion. The interfacial states were characterized by the X-ray photoelectron spectroscopy (XPS). The XPS results indicate that a strong bonding between Hf and O for Hf insertion, but no bonding between Pt and O for Pt insertion. The bonding between metal and oxygen leads to various oxygen migration behavior at the interfaces. Therefore, the opposite behavior about the RAH originates from the different oxygen behavior due to various interfacial insertion. This work provides a new approach to manipulate spin transport property for the potential applications.

  8. Single-Molecule Interfacial Electron Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Lu, H. Peter [Bowling Green State Univ., Bowling Green, OH (United States). Dept. of Chemistry and Center for Photochemical Sciences

    2017-11-28

    This project is focused on the use of single-molecule high spatial and temporal resolved techniques to study molecular dynamics in condensed phase and at interfaces, especially, the complex reaction dynamics associated with electron and energy transfer rate processes. The complexity and inhomogeneity of the interfacial ET dynamics often present a major challenge for a molecular level comprehension of the intrinsically complex systems, which calls for both higher spatial and temporal resolutions at ultimate single-molecule and single-particle sensitivities. Combined single-molecule spectroscopy and electrochemical atomic force microscopy approaches are unique for heterogeneous and complex interfacial electron transfer systems because the static and dynamic inhomogeneities can be identified and characterized by studying one molecule at a specific nanoscale surface site at a time. The goal of our project is to integrate and apply these spectroscopic imaging and topographic scanning techniques to measure the energy flow and electron flow between molecules and substrate surfaces as a function of surface site geometry and molecular structure. We have been primarily focusing on studying interfacial electron transfer under ambient condition and electrolyte solution involving both single crystal and colloidal TiO2 and related substrates. The resulting molecular level understanding of the fundamental interfacial electron transfer processes will be important for developing efficient light harvesting systems and broadly applicable to problems in fundamental chemistry and physics. We have made significant advancement on deciphering the underlying mechanism of the complex and inhomogeneous interfacial electron transfer dynamics in dyesensitized TiO2 nanoparticle systems that strongly involves with and regulated by molecule-surface interactions. We have studied interfacial electron transfer on TiO2 nanoparticle surfaces by using ultrafast single

  9. High resolution seismic stratigraphy and Mass Transport Deposits of the proximal continental margin, offshore Quarteira, South Portugal: Preliminary Results.

    Science.gov (United States)

    Duarte, Débora; Santos, Joana; Terrinha, Pedro; Brito, Pedro; Noiva, João; Ribeiro, Carlos; Roque, Cristina

    2017-04-01

    More than 300 nautical miles of multichannel seismic reflection data were acquired in the scope of the ASTARTE project (Assessment Strategy and Risk Reduction for Tsunamis in Europe), off Quarteira, Algarve, South Portugal. The main goal of this very high resolution multichannel seismic survey was to obtain high-resolution images of the sedimentary record to try to discern the existence of high energy events, possibly tsunami backwash deposits associated with large magnitude earthquakes generated at the Africa-Eurasia plate boundary This seismic dataset was processed at the Instituto Português do Mar e da Atmosfera (IPMA), with the SeisSpace PROMAX Seismic Processing software. A tailor-made processing flow was applied, focusing in the removal of the seafloor multiple and in the enhancement of the superficial layers. A sparker source, using with 300 J of energy and a fire rate of 0,5 s was used onboard Xunauta, an 18 m long vessel. The preliminary seismostratigraphic interpretation of the Algarve ASTARTE seismic dataset allowed the identification of a complex sequence seismic units of progradational and agradational bodies as well as Mass Transported Deposits (MTD). The MTD package of sediments has a very complex internal structure, 20m of thickness, is apparently spatially controlled by an escarpment probably associated to past sea level low stands. The MTD covers across an area, approximately parallel to an ancient coastline, with >30 km (length) x 5 km (across). Acknowledgements: This work was developed as part of the project ASTARTE (603839 FP7) supported by the grant agreement No 603839 of the European Union's Seventh. The Instituto Portugues do Mar e da Atmosfera acknowledges support by Landmark Graphics (SeisWorks) via the Landmark University Grant Program.

  10. Evapotranspiration: A process driving mass transport and energy exchange in the soil-plant-atmosphere-climate system

    Science.gov (United States)

    Katul, Gabriel G.; Oren, Ram; Manzoni, Stefano; Higgins, Chad; Parlange, Marc B.

    2012-09-01

    The role of evapotranspiration (ET) in the global, continental, regional, and local water cycles is reviewed. Elevated atmospheric CO2, air temperature, vapor pressure deficit (D), turbulent transport, radiative transfer, and reduced soil moisture all impact biotic and abiotic processes controlling ET that must be extrapolated to large scales. Suggesting a blueprint to achieve this link is the main compass of this review. Leaf-scale transpiration (fe) as governed by the plant biochemical demand for CO2 is first considered. When this biochemical demand is combined with mass transfer formulations, the problem remains mathematically intractable, requiring additional assumptions. A mathematical "closure" that assumes stomatal aperture is autonomously regulated so as to maximize the leaf carbon gain while minimizing water loss is proposed, which leads to analytical expressions for leaf-scale transpiration. This formulation predicts well the effects of elevated atmospheric CO2 and increases in D on fe. The case of soil moisture stress is then considered using extensive gas exchange measurements collected in drought studies. Upscaling the fe to the canopy is then discussed at multiple time scales. The impact of limited soil water availability within the rooting zone on the upscaled ET as well as some plant strategies to cope with prolonged soil moisture stress are briefly presented. Moving further up in direction and scale, the soil-plant system is then embedded within the atmospheric boundary layer, where the influence of soil moisture on rainfall is outlined. The review concludes by discussing outstanding challenges and how to tackle them by means of novel theoretical, numerical, and experimental approaches.

  11. Water/rock interactions and mass transport within a thermal gradient Application to the confinement of high level nuclear waste

    International Nuclear Information System (INIS)

    Poinssot, Ch.; Ecole Normale Superieure, 92 - Fontenay-aux-Roses

    1998-01-01

    The initial stage of a high level nuclear waste disposal will be characterised by a large heat release within the near-field environment of the canisters. This heat flux caused by radioactive decay will lead to an increase of temperature and a subsequent thermal gradient between the 'hot' canisters and the 'cold'geological medium. In addition, this thermal gradient will decrease with time due to the heat decay although it could last hundred years. What will be the consequences of such a thermal field varying both on space and time for the alteration of the different constituents of the near field environment. In particular, what could be the effects on the radionuclides migration in the accidental case of an early breach of a canister during the thermal stage? This study brings significant answers to these questions in the light of a performance assessment study. This work is supported by a triple methodological approach involving experimental studies, modelling calculations and a natural analogues study. This complete work demonstrates that a thermal gradient leads to a large re-distribution of elements within the system: some elements are incorporated in the solid phases of the hot end (Si, Zr, Ca) whereas some others are in those of the cold end (Fe, Al, Zn). The confrontation of the results of very simple experiments with the results of a model built on equilibrium thermodynamics allow us to evidence the probable mechanisms causing this mass transport: out-of-equilibrium thermodiffusion processes coupled to irreversible precipitation. Moreover, the effects of the variation of temperatures with time is studied by the way of a natural system which underwent a similar temperature evolution as a disposal and which was initially rich in uranium: the Jurassic Alpine bauxites. In addition, part of the initial bauxite escaped this temperature transformations due to their incorporation in outer thrusting nappes. They are used as a reference. (author)

  12. Thermal convection loop experiments and analysis of mass transport process in Lithium/Fe-12Cr-1MoVW systems

    International Nuclear Information System (INIS)

    Bell, G.E.C.

    1988-01-01

    Lithium is an attractive coolant and breeder material for first- generation fusion reactor blankets. The compatibility of lithium with structural alloys, in the form of mass transport and deposition, may impose restrictions on blanket operating parameters such as temperature and lithium purity. A ferritic steel, such as Fe-12CrlMoVW, is a candidate for use as a structural alloy in a self-cooled lithium blanket design. Experimental data on mass transport in lithium/Fe-12CrlMoVW were obtained from two thermal convection loops which spanned the fusion relevant temperature range; one operated from 360 to 505/degree/C for 3040 hours and the other from 525 to 655/degree/C for 2510 hours. The experimental effort was supported by analysis of the mechanisms and processes of mass transport and deposition. It was found that mass transport and deposition, as measured by specimen weight change, were not simple functions of temperature for the entire temperature range investigated. The mass transfer behavior and surface morphology at low temperatures were dominated by impurity reactions of nitrogen and carbon in the lithium with the steel. In the experiment between 360 and 505/degree/C, nitrogen levels were sufficient below 450/degree/C to allow the formation of the adherent, protective corrosion product Li 9 CrN 5 . Weight losses in the 360 to 505/degree/C experiment were insensitive to temperature below 450/degree/C. Between 450 and 505/degree/C, the precipitation of carbon in the form of chromium-rich M 23 C 6 (M = Fe or Cr) carbides, due to the formation of Li 9 CrN 5 and corresponding release of carbon, resulted in weight gains for the highest temperature specimens in the experiment. 98 refs., 83 figs., 9 tabs

  13. Chemical composition of air masses transported from Asia to the U.S. West Coast during ITCT 2K2: Fossil fuel combustion versus biomass-burning signatures

    Science.gov (United States)

    de Gouw, J. A.; Cooper, O. R.; Warneke, C.; Hudson, P. K.; Fehsenfeld, F. C.; Holloway, J. S.; Hübler, G.; Nicks, D. K., Jr.; Nowak, J. B.; Parrish, D. D.; Ryerson, T. B.; Atlas, E. L.; Donnelly, S. G.; Schauffler, S. M.; Stroud, V.; Johnson, K.; Carmichael, G. R.; Streets, D. G.

    2004-12-01

    As part of the Intercontinental Transport and Chemical Transformation experiment in 2002 (ITCT 2K2), a National Oceanic and Atmospheric Administration (NOAA) WP-3D research aircraft was used to study the long-range transport of Asian air masses toward the west coast of North America. During research flights on 5 and 17 May, strong enhancements of carbon monoxide (CO) and other species were observed in air masses that had been transported from Asia. The hydrocarbon composition of the air masses indicated that the highest CO levels were related to fossil fuel use. During the flights on 5 and 17 May and other days, the levels of several biomass-burning indicators increased with altitude. This was true for acetonitrile (CH3CN), methyl chloride (CH3Cl), the ratio of acetylene (C2H2) to propane (C3H8), and, on May 5, the percentage of particles measured by the particle analysis by laser mass spectrometry (PALMS) instrument that were attributed to biomass burning based on their carbon and potassium content. An ensemble of back-trajectories, calculated from the U.S. west coast over a range of latitudes and altitudes for the entire ITCT 2K2 period, showed that air masses from Southeast Asia and China were generally observed at higher altitudes than air from Japan and Korea. Emission inventories estimate the contribution of biomass burning to the total emissions to be low for Japan and Korea, higher for China, and the highest for Southeast Asia. Combined with the origin of the air masses versus altitude, this qualitatively explains the increase with altitude, averaged over the whole ITCT 2K2 period, of the different biomass-burning indicators.

  14. Intelligent Chiral Sensing Based on Supramolecular and Interfacial Concepts

    Directory of Open Access Journals (Sweden)

    Hironori Izawa

    2010-07-01

    Full Text Available Of the known intelligently-operating systems, the majority can undoubtedly be classed as being of biological origin. One of the notable differences between biological and artificial systems is the important fact that biological materials consist mostly of chiral molecules. While most biochemical processes routinely discriminate chiral molecules, differentiation between chiral molecules in artificial systems is currently one of the challenging subjects in the field of molecular recognition. Therefore, one of the important challenges for intelligent man-made sensors is to prepare a sensing system that can discriminate chiral molecules. Because intermolecular interactions and detection at surfaces are respectively parts of supramolecular chemistry and interfacial science, chiral sensing based on supramolecular and interfacial concepts is a significant topic. In this review, we briefly summarize recent advances in these fields, including supramolecular hosts for color detection on chiral sensing, indicator-displacement assays, kinetic resolution in supramolecular reactions with analyses by mass spectrometry, use of chiral shape-defined polymers, such as dynamic helical polymers, molecular imprinting, thin films on surfaces of devices such as QCM, functional electrodes, FET, and SPR, the combined technique of magnetic resonance imaging and immunoassay, and chiral detection using scanning tunneling microscopy and cantilever technology. In addition, we will discuss novel concepts in recent research including the use of achiral reagents for chiral sensing with NMR, and mechanical control of chiral sensing. The importance of integration of chiral sensing systems with rapidly developing nanotechnology and nanomaterials is also emphasized.

  15. Insights in the Diffusion Controlled Interfacial Flow Synthesis of Au Nanostructures in a Microfluidic System.

    Science.gov (United States)

    Kulkarni, Amol A; Sebastian Cabeza, Victor

    2017-12-19

    Continuous segmented flow interfacial synthesis of Au nanostructures is demonstrated in a microchannel reactor. This study brings new insights into the growth of nanostructures at continuous interfaces. The size as well as the shape of the nanostructures showed significant dependence on the reactant concentrations, reaction time, temperature, and surface tension, which actually controlled the interfacial mass transfer. The microchannel reactor assisted in achieving a high interfacial area, as well as uniformity in mass transfer effects. Hexagonal nanostructures were seen to be formed in synthesis times as short as 10 min. The wettability of the channel showed significant effect on the particle size as well as the actual shape. The hydrophobic channel yielded hexagonal structures of relatively smaller size than the hydrophilic microchannel, which yielded sharp hexagonal bipyramidal particles (diagonal distance of 30 nm). The evolution of particle size and shape for the case of hydrophilic microchannel is also shown as a function of the residence time. The interfacial synthesis approach based on a stable segmented flow promoted an excellent control on the reaction extent, reduction in axial dispersion as well as the particle size distribution.

  16. Interfacial Energy and Fine Defect Structures for Incoherent Films

    OpenAIRE

    Cermelli, Paolo; Gurtin, Morton E.; Leoni, Giovanni

    1999-01-01

    This note summarizes recent results in which modern techniques of the calculus of variations are used to obtain qualitative features of film-substrate interfaces for a broad class of interfacial energies. In particular, we show that the existence of a critical thickness for incoherency and the formation of interfacial dislocations depend strongly on the convexity and smoothness of the interfacial energy function.

  17. Gelation and interfacial behaviour of vegetable proteins

    NARCIS (Netherlands)

    Vliet, T. van; Martin, A.H.; Bos, M.A.

    2002-01-01

    Recent studies on gelation and interfacial properties of vegetable protiens are reviewed. Attention is focused on legume proteins, mainly soy proteins, and on wheat proteins. The rheological properteis of vegetable protein gels as a function of heating time or temperature is discussed as well as the

  18. Gelation and interfacial behaviour of vegetable proteins

    NARCIS (Netherlands)

    Vliet, van T.; Martin, A.H.; Bos, M.A.

    2002-01-01

    Recent studies on gelation and interfacial properties of vegetable proteins are reviewed. Attention is focused on legume proteins, mainly soy proteins, and on wheat proteins. The rheological properties of vegetable protein gels as a function of heating time or temperature is discussed as well as the

  19. Exchange bias mediated by interfacial nanoparticles (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Berkowitz, A. E., E-mail: aberk@ucsd.edu [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States); Center for Magnetic Recording Research, University of California, California 92093 (United States); Sinha, S. K. [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States); Fullerton, E. E. [Center for Magnetic Recording Research, University of California, California 92093 (United States); Smith, D. J. [Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States)

    2015-05-07

    The objective of this study on the iconic exchange-bias bilayer Permalloy/CoO has been to identify those elements of the interfacial microstructure and accompanying magnetic properties that are responsible for the exchange-bias and hysteretic properties of this bilayer. Both epitaxial and polycrystalline samples were examined. X-ray and neutron reflectometry established that there existed an interfacial region, of width ∼1 nm, whose magnetic properties differed from those of Py or CoO. A model was developed for the interfacial microstructure that predicts all the relevant properties of this system; namely; the temperature and Permalloy thickness dependence of the exchange-bias, H{sub EX}, and coercivity, H{sub C}; the much smaller measured values of H{sub EX} from what was nominally expected; the different behavior of H{sub EX} and H{sub C} in epitaxial and polycrystalline bilayers. A surprising result is that the exchange-bias does not involve direct exchange-coupling between Permalloy and CoO, but rather is mediated by CoFe{sub 2}O{sub 4} nanoparticles in the interfacial region.

  20. The electrostatic interaction between interfacial colloidal particles

    Science.gov (United States)

    Hurd, A. J.

    1985-11-01

    The electrostatic interaction between charged, colloidal particles trapped at an air-water interface is considered using linearised Poisson-Boltzmann results for point particles. In addition to the expected screened-Coulomb contribution, which decays exponentially, an algebraic dipole-dipole interaction occurs that may account for long-range interactions in interfacial colloidal systems.

  1. Influence of interfacial layer on contact resistance

    NARCIS (Netherlands)

    Roy, D.; In 't Zand, M.A.A.; Delhounge, R.; Klootwijk, J.H.; Wolters, Robertus A.M.

    2008-01-01

    The contact resistance between two materials is dependent on the intrinsic properties of the materials in contact and the presence and properties of an interfacial layer at the contact. This article presents the difference in contact resistance measurements with and without the presence of a process

  2. MASS TRANSPORT PROPERTIES OF A FLOW-THROUGH ELECTROLYTIC REACTOR USING A POROUS ELECTRODE: PERFORMANCE AND FIGURES OF MERIT FOR Pb(II REMOVAL

    Directory of Open Access Journals (Sweden)

    Bertazzoli R.

    1998-01-01

    Full Text Available The removal of lead from an acid borate-nitrate solution containing Pb(II was used to characterize the mass transport properties of an electrolytic reactor with reticulated vitreous carbon cathodes, operated in the flow-through mode. Current potential curves recorded at a rotating vitreous carbon disc electrode were used to determine the diffusion coefficient for Pb(II under the conditions of the experiments. The performance and figures of merit of the electrolytic reactor were investigated by using different flowrates and cathode porosities. Dimensionless Sherwood and Reynolds numbers were correlated to characterize the mass transport properties of the reactor, and they were fitted to the equation Sh=24Re0.32Sc0.33.

  3. Interfacial Properties of CZTS Thin Film Solar Cell

    Directory of Open Access Journals (Sweden)

    N. Muhunthan

    2014-01-01

    Full Text Available Cu-deficient CZTS (copper zinc tin sulfide thin films were grown on soda lime as well as molybdenum coated soda lime glass by reactive cosputtering. Polycrystalline CZTS film with kesterite structure was produced by annealing it at 500°C in Ar atmosphere. These films were characterized for compositional, structural, surface morphological, optical, and transport properties using energy dispersive X-ray analysis, glancing incidence X-ray diffraction, Raman spectroscopy, scanning electron microscopy, atomic force microscopy, UV-Vis spectroscopy, and Hall effect measurement. A CZTS solar cell device having conversion efficiency of ~0.11% has been made by depositing CdS, ZnO, ITO, and Al layers over the CZTS thin film deposited on Mo coated soda lime glass. The series resistance of the device was very high. The interfacial properties of device were characterized by cross-sectional SEM and cross-sectional HRTEM.

  4. Single-Molecule Interfacial Electron Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Wilson [Univ. of California, Irvine, CA (United States)

    2018-02-03

    Interfacial electron transfer (ET) plays an important role in many chemical and biological processes. Specifically, interfacial ET in TiO2-based systems is important to solar energy technology, catalysis, and environmental remediation technology. However, the microscopic mechanism of interfacial ET is not well understood with regard to atomic surface structure, molecular structure, bonding, orientation, and motion. In this project, we used two complementary methodologies; single-molecule fluorescence spectroscopy, and scanning-tunneling microscopy and spectroscopy (STM and STS) to address this scientific need. The goal of this project was to integrate these techniques and measure the molecular dependence of ET between adsorbed molecules and TiO2 semiconductor surfaces and the ET induced reactions such as the splitting of water. The scanning probe techniques, STM and STS, are capable of providing the highest spatial resolution but not easily time-resolved data. Single-molecule fluorescence spectroscopy is capable of good time resolution but requires further development to match the spatial resolution of the STM. The integrated approach involving Peter Lu at Bowling Green State University (BGSU) and Wilson Ho at the University of California, Irvine (UC Irvine) produced methods for time and spatially resolved chemical imaging of interfacial electron transfer dynamics and photocatalytic reactions. An integral aspect of the joint research was a significant exchange of graduate students to work at the two institutions. This project bridged complementary approaches to investigate a set of common problems by working with the same molecules on a variety of solid surfaces, but using appropriate techniques to probe under ambient (BGSU) and ultrahigh vacuum (UCI) conditions. The molecular level understanding of the fundamental interfacial electron transfer processes obtained in this joint project will be important for developing efficient light harvesting

  5. Evaluation of chemical transport model predictions of primary organic aerosol for air masses classified by particle-component-based factor analysis

    OpenAIRE

    C. A. Stroud; M. D. Moran; P. A. Makar; S. Gong; W. Gong; J. Zhang; J. G. Slowik; J. P. D. Abbatt; G. Lu; J. R. Brook; C. Mihele; Q. Li; D. Sills; K. B. Strawbridge; M. L. McGuire

    2012-01-01

    Observations from the 2007 Border Air Quality and Meteorology Study (BAQS-Met 2007) in Southern Ontario, Canada, were used to evaluate predictions of primary organic aerosol (POA) and two other carbonaceous species, black carbon (BC) and carbon monoxide (CO), made for this summertime period by Environment Canada's AURAMS regional chemical transport model. Particle component-based factor analysis was applied to aerosol mass spectrometer measurements made at one urban site (Windsor, ON) and two...

  6. Monte Carlo studies on the interfacial properties and interfacial structures of ternary symmetric blends with gradient copolymers.

    Science.gov (United States)

    Sun, Dachuan; Guo, Hongxia

    2012-08-09

    Using Monte Carlo simulation methods, the effects of the comonomer sequence distribution on the interfacial properties (including interfacial tension, interfacial thickness, saturated interfacial area per copolymer, and bending modulus) and interfacial structures (including chain conformations and comonomer distributions of the simulated copolymers at the interfaces) of a ternary symmetric blend containing two immiscible homopolymers and one gradient copolymer are investigated. We find that copolymers with a larger composition gradient width have a broader comonomer distribution along the interface normal, and hence more pronouncedly enlarge the interfacial thickness and reduce the interfacial tension. Furthermore, the counteraction effect, which arises from the tendency of heterogeneous segments in gradient copolymers to phase separate and enter their miscible phases to reduce the local enthalpy, decreases the stretching of copolymers along the interface normal direction. As a result, copolymers with a larger width of gradient composition can occupy a larger interfacial area and form softer monolayers at saturation and are more efficient in facilitating the formation of bicontinuous microemulsions. Additionally, chain length ratio, segregation strength, and interactions between homopolymers and copolymers can alter the interfacial character of gradient copolymers. There exists a strong coupling between the comonomer sequence distribution, chain conformation, and interfacial properties. Especially, bending modulus is mainly determined by the complicated interplay of interfacial copolymer density and interfacial chain conformation.

  7. Assessment of the hydrologic setting and mass transport within Saharan and Arabian Aquifers using GRACE, geochemical, geophysical and subsurface data

    Science.gov (United States)

    Sultan, M.; Sturchio, N. C.; Ahmed, M.; Saleh, S.; Mohamed, A.; Abuabdullah, M. M.; Emil, M. K.; Bettadpur, S. V.; Save, H.; Fathy, K.; Chouinard, K.

    2016-12-01

    A better understanding of the hydrologic setting, mass transport, origin, evolution, utilization, sustainability, and paleo-climatic recharge conditions of Saharan and Arabian aquifers was achieved by integrating observation from monthly (04/2002 to 03/2016) Gravity Recovery and Climate Experiment (GRACE)-derived Terrestrial Water Storage (TWS) from multiple GRACE solutions (mascons and spherical harmonic fields) with others from geochemical (solute chemistry), isotopic (O, H, Sr), geochronologic (Chlorine-36, Krypton-81), geophysical (aerogravity and aeromagnetic), and subsurface data. The investigated aquifers are: (1) Nubian Sandstone Aquifer System (NSAS; area: 2×106 km2) in northeast Africa and, (2) Mega Aquifer System (MAS; area: 1.1×106 km2) in Arabia. Our findings indicate the NSAS and MAS were largely recharged in previous wet climatic Pleistocene periods, as evidenced by the groundwater ages (up to 1 million years), yet they receive modest local recharge during interleaving dry periods in areas of relatively high (≥ 20 mm/yr) precipitation. In Sudan and Chad (southern NSAS), the average annual precipitation (AAP) is 95 mm/yr and the recharge is estimated at 3.2 x 109 m3/yr ( 7% of AAP); in the southwest parts of the MAS, the recharge at the foothills of the Red Sea mountains is 1.8 x 109 m3/yr (10% of AAP). Uplifts and/or shear zones orthogonal to groundwater flow impede the south to north flow in the NSAS as evidenced by the large differences in GRACE-derived TWS trends, groundwater ages, and isotopic compositions on either side of the east-west trending Uweinat-Aswan uplift. Similarly west to east groundwater flow in the MAS is impeded and impounded up-gradient from the N-S and/or NW-SE trending basement structures, reactivated during Red Sea opening. Shear zones subparallel to groundwater flow act as preferred flow pathways, as is the case with the NE-SW trending Pelusium shear zone which channels groundwater from the Kufra sub-basin (Libya

  8. Model calculation of the characteristic mass for convective and diffusive vapor transport in graphite furnace atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Bencs, László, E-mail: bencs.laszlo@wigner.mta.hu [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Laczai, Nikoletta [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Ajtony, Zsolt [Institute of Food Science, University of West Hungary, H-9200 Mosonmagyaróvár, Lucsony utca 15–17 (Hungary)

    2015-07-01

    A combination of former convective–diffusive vapor-transport models is described to extend the calculation scheme for sensitivity (characteristic mass — m{sub 0}) in graphite furnace atomic absorption spectrometry (GFAAS). This approach encompasses the influence of forced convection of the internal furnace gas (mini-flow) combined with concentration diffusion of the analyte atoms on the residence time in a spatially isothermal furnace, i.e., the standard design of the transversely heated graphite atomizer (THGA). A couple of relationships for the diffusional and convectional residence times were studied and compared, including in factors accounting for the effects of the sample/platform dimension and the dosing hole. These model approaches were subsequently applied for the particular cases of Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Mo, Ni, Pb, Sb, Se, Sn, V and Zn analytes. For the verification of the accuracy of the calculations, the experimental m{sub 0} values were determined with the application of a standard THGA furnace, operating either under stopped, or mini-flow (50 cm{sup 3} min{sup −1}) of the internal sheath gas during atomization. The theoretical and experimental ratios of m{sub 0}(mini-flow)-to-m{sub 0}(stop-flow) were closely similar for each study analyte. Likewise, the calculated m{sub 0} data gave a fairly good agreement with the corresponding experimental m{sub 0} values for stopped and mini-flow conditions, i.e., it ranged between 0.62 and 1.8 with an average of 1.05 ± 0.27. This indicates the usability of the current model calculations for checking the operation of a given GFAAS instrument and the applied methodology. - Highlights: • A calculation scheme for convective–diffusive vapor loss in GFAAS is described. • Residence time (τ) formulas were compared for sensitivity (m{sub 0}) in a THGA furnace. • Effects of the sample/platform dimension and dosing hole on τ were assessed. • Theoretical m{sub 0} of 18 analytes were

  9. Left ventricular mass in dialysis patients, determinants and relation with outcome. Results from the COnvective TRansport STudy (CONTRAST.

    Directory of Open Access Journals (Sweden)

    Ira M Mostovaya

    Full Text Available BACKGROUND AND OBJECTIVES: Left ventricular mass (LVM is known to be related to overall and cardiovascular mortality in end stage kidney disease (ESKD patients. The aims of the present study are 1 to determine whether LVM is associated with mortality and various cardiovascular events and 2 to identify determinants of LVM including biomarkers of inflammation and fibrosis. DESIGN SETTING PARTICIPANTS & MEASUREMENTS: Analysis was performed with data of 327 ESKD patients, a subset from the CONvective TRAnsport STudy (CONTRAST. Echocardiography was performed at baseline. Cox regression analysis was used to assess the relation of LVM tertiles with clinical events. Multivariable linear regression models were used to identify factors associated with LVM. RESULTS: Median age was 65 (IQR: 54-73 years, 203 (61% were male and median LVM was 227 (IQR: 183-279 grams. The risk of all-cause mortality (hazard ratio (HR = 1.73, 95% CI: 1.11-2.99, cardiovascular death (HR = 3.66, 95% CI: 1.35-10.05 and sudden death (HR = 13.06; 95% CI: 6.60-107 was increased in the highest tertile (>260 grams of LVM. In the multivariable analysis positive relations with LVM were found for male gender (B = 38.8±10.3, residual renal function (B = 17.9±8.0, phosphate binder therapy (B = 16.9±8.5, and an inverse relation for a previous kidney transplantation (B = -41.1±7.6 and albumin (B = -2.9±1.1. Interleukin-6 (Il-6, high-sensitivity C-reactive protein (hsCRP, hepcidin-25 and connective tissue growth factor (CTGF were not related to LVM. CONCLUSION: We confirm the relation between a high LVM and outcome and expand the evidence for increased risk of sudden death. No relationship was found between LVM and markers of inflammation and fibrosis. TRIAL REGISTRATION: Controlled-Trials.com ISRCTN38365125.

  10. Interfacial reactions in thermoelectric modules

    KAUST Repository

    Wu, Hsin-jay

    2018-02-21

    Engineering transport properties of thermoelectric (TE) materials leads to incessantly breakthroughs in the zT values. Nevertheless, modular design holds a key factor to advance the TE technology. Herein, we discuss the structures of TE module and illustrate the inter-diffusions across the interface of constituent layers. For Bi2Te3-based module, soldering is the primary bonding method, giving rise to the investigations on the selections of solder, diffusion barrier layer and electrode. For mid-temperature PbTe-based TE module, hot-pressing or spark plasma sintering are alternative bonding approaches; the inter-diffusions between the diffusion barrier layer, electrode and TE substrate are addressed as well.

  11. Computational analysis of coupled fluid, heat, and mass transport in ferrocyanide single-shell tanks: FY 1994 interim report. Ferrocyanide Tank Safety Project

    International Nuclear Information System (INIS)

    McGrail, B.P.

    1994-11-01

    A computer modeling study was conducted to determine whether natural convection processes in single-shell tanks containing ferrocyanide wastes could generate localized precipitation zones that significantly concentrate the major heat-generating radionuclide, 137 Cs. A computer code was developed that simulates coupled fluid, heat, and single-species mass transport on a regular, orthogonal finite-difference grid. The analysis showed that development of a ''hot spot'' is critically dependent on the temperature dependence for the solubility of Cs 2 NiFe(CN) 6 or CsNaNiFe(CN) 6 . For the normal case, where solubility increases with increasing temperature, the net effect of fluid flow, heat, and mass transport is to disperse any local zones of high heat generation rate. As a result, hot spots cannot physically develop for this case. However, assuming a retrograde solubility dependence, the simulations indicate the formation of localized deposition zones that concentrate the 137 Cs near the bottom center of the tank where the temperatures are highest. Recent experimental studies suggest that Cs 2 NiFe(CN) 6 (c) does not exhibit retrograde solubility over the temperature range 25 degree C to 90 degree C and NaOH concentrations to 5 M. Assuming these preliminary results are confirmed, no natural mass transport process exists for generating a hot spot in the ferrocyanide single-shell tanks

  12. Transport Regimes of Air Masses Affecting the Tropospheric Composition of the Canadian and European Arctic During RACEPAC 2014 and NETCARE 2014/2015

    Science.gov (United States)

    Bozem, H.; Hoor, P. M.; Koellner, F.; Kunkel, D.; Schneider, J.; Schulz, C.; Herber, A. B.; Borrmann, S.; Wendisch, M.; Ehrlich, A.; Leaitch, W. R.; Willis, M. D.; Burkart, J.; Thomas, J. L.; Abbatt, J.

    2015-12-01

    The Arctic is warming much faster than any other place in the world and undergoes a rapid change dominated by a changing climate in this region. The impact of polluted air masses traveling to the Arctic from various remote sources significantly contributes to the observed climate change, in contrast there are additional local emission sources contributing to the level of pollutants (trace gases and aerosol). Processes affecting the emission and transport of these pollutants are not well understood and need to be further investigated. We present aircraft based trace gas measurements in the Arctic during RACEPAC (2014) and NETCARE (2014 and 2015) with the Polar 6 aircraft of Alfred Wegener Institute (AWI) covering an area from 134°W to 17°W and 68°N to 83°N. We focus on cloud, aerosol and general transport processes of polluted air masses into the high Arctic. Based on CO and CO2 measurements and kinematic 10-day back trajectories we analyze the transport regimes prevalent during spring (RACEPAC 2014 and NETCARE 2015) and summer (NETCARE 2014) in the observed region. Whereas the eastern part of the Canadian Arctic is affected by air masses with their origin in Asia, in the central and western parts of the Canadian and European Arctic air masses from North America are predominant at the time of the measurement. In general the more northern parts of the Arctic were relatively unaffected by pollution from mid-latitudes since air masses mostly travel within the polar dome, being quite isolated. Associated mixing ratios of CO and CO2 fit into the seasonal cycle observed at NOAA ground stations throughout the Arctic, but show a more mid-latitudinal characteristic at higher altitudes. The transition is remarkably sharp and allows for a chemical definition of the polar dome. At low altitudes, synoptic disturbances transport polluted air masses from mid-latitudes into regions of the polar dome. These air masses contribute to the Arctic pollution background, but also

  13. The effects of interfacial recombination and injection barrier on the electrical characteristics of perovskite solar cells

    Directory of Open Access Journals (Sweden)

    Lin Xing Shi

    2018-02-01

    Full Text Available Charge carrier recombination in the perovskite solar cells (PSCs has a deep influence on the electrical performance, such as open circuit voltage, short circuit current, fill factor and ultimately power conversion efficiency. The impacts of injection barrier, recombination channels, doping properties of carrier transport layers and light intensity on the performance of PSCs are theoretically investigated by drift-diffusion model in this work. The results indicate that due to the injection barrier at the interfaces of perovskite and carrier transport layer, the accumulated carriers modify the electric field distribution throughout the PSCs. Thus, a zero electric field is generated at a specific applied voltage, with greatly increases the interfacial recombination, resulting in a local kink of current density-voltage (J-V curve. This work provides an effective strategy to improve the efficiency of PSCs by pertinently reducing both the injection barrier and interfacial recombination.

  14. Chemical characterization of long-range transport biomass burning emissions to the Himalayas: insights from high-resolution aerosol mass spectrometry

    Science.gov (United States)

    Zhang, Xinghua; Xu, Jianzhong; Kang, Shichang; Liu, Yanmei; Zhang, Qi

    2018-04-01

    An intensive field measurement was conducted at a remote, background, high-altitude site (Qomolangma Station, QOMS, 4276 m a.s.l.) in the northern Himalayas, using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) along with other collocated instruments. The field measurement was performed from 12 April to 12 May 2016 to chemically characterize the high time-resolved submicron particulate matter (PM1) and obtain the dynamic processes (emissions, transport, and chemical evolution) of biomass burning (BB), frequently transported from South Asia to the Himalayas during pre-monsoon season. Overall, the average (±1σ) PM1 mass concentration was 4.44 (±4.54) µg m-3 for the entire study, which is comparable with those observed at other remote sites worldwide. Organic aerosol (OA) was the dominant PM1 species (accounting for 54.3 % of total PM1 on average) followed by black carbon (BC) (25.0 %), sulfate (9.3 %), ammonium (5.8 %), nitrate (5.1 %), and chloride (0.4 %). The average size distributions of PM1 species all peaked at an overlapping accumulation mode (˜ 500 nm), suggesting that aerosol particles were internally well-mixed and aged during long-range transport. Positive matrix factorization (PMF) analysis on the high-resolution organic mass spectra identified three distinct OA factors, including a BB-related OA (BBOA, 43.7 %), a nitrogen-containing OA (NOA, 13.9 %) and a more-oxidized oxygenated OA (MO-OOA, 42.4 %). Two polluted episodes with enhanced PM1 mass loadings and elevated BBOA contributions from the west and southwest of QOMS during the study were observed. A typical BB plume was investigated in detail to illustrate the chemical evolution of aerosol characteristics under distinct air mass origins, meteorological conditions, and atmospheric oxidation processes.

  15. Electrode Cultivation and Interfacial Electron Transport in Subsurface Microorganisms

    Science.gov (United States)

    Karbelkar, A. A.; Jangir, Y.; Reese, B. K.; Wanger, G.; Anderson, C.; El-Naggar, M.; Amend, J.

    2016-12-01

    Continental subsurface environments can present significant energetic challenges to the resident microorganisms. While these environments are geologically diverse, potentially allowing energy harvesting by microorganisms that catalyze redox reactions, many of the abundant electron donors and acceptors are insoluble and therefore not directly bioavailable. Microbes can use extracellular electron transfer (EET) as a metabolic strategy to interact with redox active surfaces. This process can be mimicked on electrode surfaces and hence can lead to enrichment and quantification of subsurface microorganisms A primary bioelectrochemical enrichment with different oxidizing and reducing potentials set up in a single bioreactor was applied in situ to subsurface microorganisms residing in iron oxide rich deposits in the Sanford Underground Research Facility. Secondary enrichment revealed a plethora of classified and unclassified subsurface microbiota on both oxidizing and reducing potentials. From this enrichment, we have isolated a Gram-positive Bacillus along with Gram-negative Cupriavidus and Anaerospora strains (as electrode reducers) and Comamonas (as an electrode oxidizer). The Bacillus and Comamonas isolates were subjected to a detailed electrochemical characterization in half-reactors at anodic and cathodic potentials, respectively. An increase in cathodic current upon inoculation and cyclic voltammetry measurements confirm the hypothesis that Comamonas is capable of electron uptake from electrodes. In addition, measurements of Bacillus on anodes hint towards novel mechanisms that allow EET from Gram-positive bacteria. This study suggests that electrochemical approaches are well positioned to dissect such extracellular interactions that may be prevalent in the subsurface, while using physical electrodes to emulate the microhabitats, redox and geochemical gradients, and the spatially dependent interspecies interactions encountered in the subsurface. Electrochemical characterization of isolated strains can help us establish the possible mechanisms of EET, and hence provide an insight on survival strategies of subsurface microbiota in extreme environments. Continental subsurface environments can present significant energetic challenges to the resident microorganisms. While these environments are geologically diverse, potentially allowing energy harvesting by microorganisms that catalyze redox reactions, many of the abundant electron donors and acceptors are insoluble and therefore not directly bioavailable. Microbes can use extracellular electron transfer (EET) as a metabolic strategy to interact with redox active surfaces. This process can be mimicked on electrode surfaces and hence can lead to enrichment and quantification of subsurface microorganisms A primary bioelectrochemical enrichment with different oxidizing and reducing potentials set up in a single bioreactor was applied in situ to subsurface microorganisms residing in iron oxide rich deposits in the Sanford Underground Research Facility. Secondary enrichment revealed a plethora of classified and unclassified subsurface microbiota on both oxidizing and reducing potentials. From this enrichment, we have isolated a Gram-positive Bacillus along with Gram-negative Cupriavidus and Anaerospora strains (as electrode reducers) and Comamonas (as an electrode oxidizer). The Bacillus and Comamonas isolates were subjected to a detailed electrochemical characterization in half-reactors at anodic and cathodic potentials, respectively. An increase in cathodic current upon inoculation and cyclic voltammetry measurements confirm the hypothesis that Comamonas is capable of electron uptake from electrodes. In addition, measurements of Bacillus on anodes hint towards novel mechanisms that allow EET from Gram-positive bacteria. This study suggests that electrochemical approaches are well positioned to dissect such extracellular interactions that may be prevalent in the subsurface, while using physical electrodes to emulate the microhabitats, redox and geochemical gradients, and the spatially dependent interspecies interactions encountered in the subsurface. Electrochemical characterization of isolated strains can help us establish the possible mechanisms of EET, and hence provide an insight on survival strategies of subsurface microbiota in extreme environments.

  16. Computational modeling for fluid flow and interfacial transport

    CERN Document Server

    Shyy, Wei

    2006-01-01

    Practical applications and examples highlight this treatment of computational modeling for handling complex flowfields. A reference for researchers and graduate students of many different backgrounds, it also functions as a text for learning essential computation elements.Drawing upon his own research, the author addresses both macroscopic and microscopic features. He begins his three-part treatment with a survey of the basic concepts of finite difference schemes for solving parabolic, elliptic, and hyperbolic partial differential equations. The second part concerns issues related to computati

  17. Study on the Mechanical and Interfacial Property of Injection Molded Fiber Reinforced Thermoplastics

    OpenAIRE

    王, 存涛

    2014-01-01

    Fiber reinforced polymer (FRP) composites have been used widely in the land transportation, aerospace, marine structures and characteristically conservative infrastructure construction industries and generally, the interface plays very important role in the properties of FRP materials. Therefore, this research studied the mechanical and interfacial property involved in the non-weld samples, weld samples and adhesive samples of insert moldings. Green composites as one of environment-friendly m...

  18. Assessment of interfacial heat transfer models under subcooled flow boiling

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Guilherme B.; Braz Filho, Francisco A., E-mail: gbribeiro@ieav.cta.br, E-mail: fbraz@ieav.cta.br [Instituto de Estudos Avançados (DCTA/IEAv), São José dos Campos, SP (Brazil). Div. de Energia Nuclear

    2017-07-01

    The present study concerns a detailed analysis of subcooled flow boiling characteristics under high pressure systems using a two-fluid Eulerian approach provided by a Computational Fluid Dynamics (CFD) solver. For this purpose, a vertical heated pipe made of stainless steel with an internal diameter of 15.4 mm was considered as the modeled domain. An uniform heat flux of 570 kW/m2 and saturation pressure of 4.5 MPa were applied to the channel wall, whereas water mass flux of 900 kg/m2s was considered for all simulation cases. The model was validated against a set of experimental data and results have indicated a promising use of CFD technique for the estimation of wall temperature, the liquid bulk temperature and the location of the departure of nucleate boiling. Different sub-models of interfacial heat transfer coefficient were applied and compared, allowing a better prediction of void fraction along the heated channel. (author)

  19. Light extinction by fine atmospheric particles in the White Mountains region of New Hampshire and its relationship to air mass transport.

    Science.gov (United States)

    Slater, John F; Dibb, Jack E; Keim, Barry D; Talbot, Robert W

    2002-03-27

    Chemical, optical, and physical measurements of fine aerosols (aerodynamic diameter mass origin. Filter-based, 24-h integrated samples were collected and analyzed for major inorganic ions, as well as organic (OC), elemental (EC), and total carbon. Light scattering and light absorption coefficients were measured at 5-min intervals using an integrating nephelometer and a light absorption photometer. Fine particle number density was measured with a condensation particle counter. Air mass origins and transport patterns were investigated through the use of 3-day backward trajectories and a synoptic climate classification system. Two distinct transport regimes were observed: (1) flow from the north/northeast (N/NE) occurred during 9 out of 18 sample-days; and (2) flow from the west/southwest (W/SW) occurred 8 out of 18 sample-days. All measured and derived aerosol and meteorological parameters were separated into two categories based on these different flow scenarios. During W/SW flow, higher values of aerosol chemical concentration, absorption and scattering coefficients, number density, and haziness were observed compared to N/NE flow. The highest level of haziness was associated with the climate classification Frontal Atlantic Return, which brought polluted air into the region from the mid-Atlantic corridor. Fine particle mass scattering efficiencies of (NH4)2SO4 and OC were 5.35 +/- 0.42 m2 g(-1) and 1.56 +/- 0.40 m2 g(-1), respectively, when transport was out of the N/NE. When transport was from the W/SW the values were 4.94 +/- 0.68 m2 g(-1) for (NH4)2SO4 and 2.18 +/- 0.91 m2 g(-1) for OC. EC mass absorption efficiency when transport was from the N/NE was 9.66 +/- 1.06 m2 g(-1) and 10.80 +/- 1.76 m2 g(-1) when transport was from the W/SW. Results from this work can be used to predict visual air quality in the White Mountain National Forest based on a forecasted synoptic climate classification and its associated visibility.

  20. Interfacial scattering effect on anisotropic magnetoresistance and anomalous Hall effect in Ta/Fe multilayers

    KAUST Repository

    Zhang, Qiang

    2017-12-26

    The effect of interfacial scattering on anisotropic magnetoresistance (AMR) and anomalous Hall effect (AHE) was studied in the (Ta12n/Fe36n)n multilayers, where the numbers give the thickness in nanometer and n is an integer from 1 to 12. The multilayer structure has been confirmed by the XRR spectra and STEM images of cross-sections. The magneto-transport properties were measured by four-point probe method in Hall bar shaped samples in the temperature range of 5 - 300 K. The AMR increases with n, which could be ascribed to the interfacial spin-orbit scattering. At 5 K, the longitudinal resistivity (ρ) increases by 6.4 times and the anomalous Hall resistivity (ρ) increases by 49.4 times from n =1 to n =12, indicative of the interfacial scattering effect. The skew-scattering, side-jump and intrinsic contributions to the AHE were separated successfully. As n increases from 1 to 12, the intrinsic contribution decreases because of the decaying crystallinity or finite size effect and the intrinsic contribution dominated the AHE for all samples. The side jump changes from negative to positive because the interfacial scattering and intralayer scattering in Fe layers both contribute to side jump in the AHE but with opposite sign.

  1. Basic study on mass transportation systems in buildings by means of multiple-cage elevators; Junkangata erebeta ni yoru biru nai tairyo yuso sisutemu no kiso kento

    Energy Technology Data Exchange (ETDEWEB)

    Fujino, A.; Tobita, T. [Hitachi, Ltd., Tokyo (Japan); Nakagawa, K. [Shimizu Corporation, Tokyo (Japan)

    1997-06-20

    From the viewpoints of realization of mass transportation, improvement of space factor in buildings, transportation systems in buildings are surveyed to compare the characteristics. Then, a loop-type independently-driven multiple-cage elevator (circulating elevator) system is proposed to estimate its transportation capacity, and necessary data for realizing transportation capacity higher than twice that of the conventional elevator are presented. As regards operational control, a high efficient control method is proposed which can restrain needless stops particular to the multiple-cage system and improve the waiting time and round trip time, and the result of the investigation by simulation is reported. Basic operation method of the loop-type elevator is determined, and the transportation capacity is estimated by simulation. The application in which the loop-type elevator can exhibit the best performance is its use in 15 floor-class buildings or for local bank zones in large-scale buildings in a system combined with the shuttle system. 9 refs., 12 figs., 5 tabs.

  2. Quality of mass-reared codling moth (Lepidoptera: Tortricidae) after long-distance transportation: 1. Logistics of shipping procedures and quality parameters as measured in the laboratory.

    Science.gov (United States)

    Blomefield, T; Carpenter, J E; Vreysen, M J B

    2011-06-01

    The sterile insect technique (SIT) is a proven effective control tactic against lepidopteran pests when applied in an areawide integrated pest management program. The construction of insect mass-rearing facilities requires considerable investment and moth control strategies that include the use of sterile insects could be made more cost-effective through the importation of sterile moths produced in other production centers. For codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), this is an attractive option because mating studies have confirmed the absence of mating barriers between codling moth populations from geographically different areas. To assess the feasibility of long-distance transportation of codling moths, pupae and adult moths were transported in 2004 from Canada to South Africa in four shipments by using normal commercial transport routes. The total transport time remained below 67 h in three of the consignments, but it was 89 h in the fourth consignment. Temperature in the shipping boxes was fairly constant and remained between -0.61 and 0.16 degrees C for 76.8-85.7% of the time. The data presented indicate that transporting codling moths as adults and pupae from Canada to South Africa had little effect on moth emergence, longevity, and ability to mate, as assessed in the laboratory. These results provide support to the suggestion that the STT for codling moth in pome fruit production areas might be evaluated and implemented by the importation of irradiated moths from rearing facilities in a different country or hemisphere.

  3. Co-Transport of Polycyclic Aromatic Hydrocarbons by Motile Microorganisms Leads to Enhanced Mass Transfer under Diffusive Conditions

    DEFF Research Database (Denmark)

    Gilbert, Dorthea; Jakobsen, Hans H.; Winding, Anne

    2014-01-01

    as sink and source for polycyclic aromatic hydrocarbons (PAHs). This resulted in stable concentration gradients in water (>24 h). Adding the model organism Tetrahymena pyriformis to the experimental system enhanced PAH mass transfer up to hundred-fold (benzo[a]pyrene). Increasing mass transfer enhancement...

  4. Frontiers of interfacial water research :workshop report.

    Energy Technology Data Exchange (ETDEWEB)

    Cygan, Randall Timothy; Greathouse, Jeffery A.

    2005-10-01

    Water is the critical natural resource of the new century. Significant improvements in traditional water treatment processes require novel approaches based on a fundamental understanding of nanoscale and atomic interactions at interfaces between aqueous solution and materials. To better understand these critical issues and to promote an open dialog among leading international experts in water-related specialties, Sandia National Laboratories sponsored a workshop on April 24-26, 2005 in Santa Fe, New Mexico. The ''Frontiers of Interfacial Water Research Workshop'' provided attendees with a critical review of water technologies and emphasized the new advances in surface and interfacial microscopy, spectroscopy, diffraction, and computer simulation needed for the development of new materials for water treatment.

  5. Mesoscale Interfacial Dynamics in Magnetoelectric Nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Shashank, Priya [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)

    2009-12-14

    Biphasic composites are the key towards achieving enhanced magnetoelectric response. In order understand the control behavior of the composites and resultant symmetry of the multifunctional product tensors, we need to synthesized model material systems with the following features (i) interface formation through either deposition control or natural decomposition; (ii) a very high interphase-interfacial area, to maximize the ME coupling; and (iii) an equilibrium phase distribution and morphology, resulting in preferred crystallographic orientation relations between phases across the interphase-interfacial boundaries. This thought process guided the experimental evolution in this program. We initiated the research with the co-fired composites approach and then moved on to the thin film laminates deposited through the rf-magnetron sputtering and pulsed laser deposition process

  6. Interfacial Fluid Mechanics A Mathematical Modeling Approach

    CERN Document Server

    Ajaev, Vladimir S

    2012-01-01

    Interfacial Fluid Mechanics: A Mathematical Modeling Approach provides an introduction to mathematical models of viscous flow used in rapidly developing fields of microfluidics and microscale heat transfer. The basic physical effects are first introduced in the context of simple configurations and their relative importance in typical microscale applications is discussed. Then,several configurations of importance to microfluidics, most notably thin films/droplets on substrates and confined bubbles, are discussed in detail.  Topics from current research on electrokinetic phenomena, liquid flow near structured solid surfaces, evaporation/condensation, and surfactant phenomena are discussed in the later chapters. This book also:  Discusses mathematical models in the context of actual applications such as electrowetting Includes unique material on fluid flow near structured surfaces and phase change phenomena Shows readers how to solve modeling problems related to microscale multiphase flows Interfacial Fluid Me...

  7. Evaluating interfacial shear stresses in composite hollo

    Directory of Open Access Journals (Sweden)

    Aiham Adawi

    2016-09-01

    Full Text Available Analytical evaluation of the interfacial shear stresses for composite hollowcore slabs with concrete topping is rare in the literature. Adawi et al. (2014 estimated the interfacial shear stiffness coefficient (ks that governs the behavior of the interface between hollowcore slabs and the concrete topping using push-off tests. This parameter is utilized in this paper to provide closed form solutions for the differential equations governing the behavior of simply supported composite hollowcore slabs. An analytical solution based on the deformation compatibility of the composite section and elastic beam theory, is developed to evaluate the shear stresses along the interface. Linear finite element modeling of the full-scale tests presented in Adawi et al. (2015 is also conducted to validate the developed analytical solution. The proposed analytical solution was found to be adequate in estimating the magnitude of horizontal shear stress in the studied composite hollowcore slabs.

  8. Estimation of transport parameters of phenolic compounds and inorganic contaminants through composite landfill liners using one-dimensional mass transport model

    International Nuclear Information System (INIS)

    Varank, Gamze; Demir, Ahmet; Yetilmezsoy, Kaan; Bilgili, M. Sinan; Top, Selin; Sekman, Elif

    2011-01-01

    Highlights: → We conduct 1D advection-dispersion modeling to estimate transport parameters. → We examine fourteen phenolic compounds and three inorganic contaminants. → 2-MP, 2,4-DCP, 2,6-DCP, 2,4,5-TCP, 2,3,4,6-TeCP have the highest coefficients. → Dispersion coefficients of Cu are determined to be higher than Zn and Fe. → Transport of phenolics can be prevented by zeolite and bentonite in landfill liners. - Abstract: One-dimensional (1D) advection-dispersion transport modeling was conducted as a conceptual approach for the estimation of the transport parameters of fourteen different phenolic compounds (phenol, 2-CP, 2-MP, 3-MP, 4-MP, 2-NP, 4-NP, 2,4-DNP, 2,4-DCP, 2,6-DCP, 2,4,5-TCP, 2,4,6-TCP, 2,3,4,6-TeCP, PCP) and three different inorganic contaminants (Cu, Zn, Fe) migrating downward through the several liner systems. Four identical pilot-scale landfill reactors (0.25 m 3 ) with different composite liners (R1: 0.10 + 0.10 m of compacted clay liner (CCL), L e = 0.20 m, k e = 1 x 10 -8 m/s, R2: 0.002-m-thick damaged high-density polyethylene (HDPE) geomembrane overlying 0.10 + 0.10 m of CCL, L e = 0.20 m, k e = 1 x 10 -8 m/s, R3: 0.002-m-thick damaged HDPE geomembrane overlying a 0.02-m-thick bentonite layer encapsulated between 0.10 + 0.10 m CCL, L e = 0.22 m, k e = 1 x 10 -8 m/s, R4: 0.002-m-thick damaged HDPE geomembrane overlying a 0.02-m-thick zeolite layer encapsulated between 0.10 + 0.10 m CCL, L e = 0.22 m, k e = 4.24 x 10 -7 m/s) were simultaneously run for a period of about 540 days to investigate the nature of diffusive and advective transport of the selected organic and inorganic contaminants. The results of 1D transport model showed that the highest molecular diffusion coefficients, ranging from 4.77 x 10 -10 to 10.67 x 10 -10 m 2 /s, were estimated for phenol (R4), 2-MP (R1), 2,4-DNP (R2), 2,4-DCP (R1), 2,6-DCP (R2), 2,4,5-TCP (R2) and 2,3,4,6-TeCP (R1). For all reactors, dispersion coefficients of Cu, ranging from 3.47 x 10 -6 m 2 /s to 5

  9. Facile Interfacial Electron Transfer of Hemoglobin

    Directory of Open Access Journals (Sweden)

    Chunhai Fan

    2005-12-01

    Full Text Available Abstract: We herein describe a method of depositing hemoglobin (Hb and sulfonated polyaniline (SPAN on GC electrodes that facilitate interfacial protein electron transfer. Well-defined, reproducible, chemically reversible peaks of Hb and SPAN can be obtained in our experiments. We also observed enhanced peroxidase activity of Hb in SPAN films. These results clearly showed that SPAN worked as molecular wires and effectively exchanged electrons between Hb and electrodes.Mediated by Conjugated Polymers

  10. Interfacial Studies of Sized Carbon Fiber

    International Nuclear Information System (INIS)

    Shahrul, S. N.; Hartini, M. N.; Hilmi, E. A.; Nizam, A.

    2010-01-01

    This study was performed to investigate the influence of sizing treatment on carbon fiber in respect of interfacial adhesion in composite materials, Epolam registered 2025. Fortafil unsized carbon fiber was used to performed the experiment. The fiber was commercially surface treated and it was a polyacrylonitrile based carbon fiber with 3000 filament per strand. Epicure registered 3370 was used as basic sizing chemical and dissolved in two types of solvent, ethanol and acetone for the comparison purpose. The single pull out test has been used to determine the influence of sizing on carbon fiber. The morphology of carbon fiber was observed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The apparent interfacial strength IFSS values determined by pull out test for the Epicure registered 3370/ethanol sized carbon fiber pointed to a good interfacial behaviour compared to the Epicure registered 3370/acetone sized carbon fiber. The Epicure registered 3370/ethanol sizing agent was found to be effective in promoting adhesion because of the chemical reactions between the sizing and Epolam registered 2025 during the curing process. From this work, it showed that sized carbon fiber using Epicure registered 3370 with addition of ethanol give higher mechanical properties of carbon fiber in terms of shear strength and also provided a good adhesion between fiber and matrix compared to the sizing chemical that contain acetone as a solvent.

  11. A radiotracer study on the volatilization and transport effects of thermochemical reagents used in the analysis of alumina powders by slurry electrothermal vaporization inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Peschel, Birgit U.; Herdering, Wilhelm; Broekaert, Jose A.C.

    2007-01-01

    A neutron-activated Al 2 O 3 powder SRM 699 (NIST) containing the γ-radiation emitting radionuclides 51 Cr, 59 Fe, 60 Co and 65 Zn has been used to study the influence of thermochemical reagents on the volatilization and transport efficiency for these trace elements in electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) of Al 2 O 3 powders. From the signals in the γ-spectra for the radiotracers it has been found that less than 2% of the elements Cr, Fe, Co and Zn is left back in a graphite furnace from Al 2 O 3 powders at 2200 deg. C even without addition of a thermochemical reagent and the latter even was found to decrease the volatilization efficiencies. The recovery for the radiotracers on filters at the end of the transport tube as measured from the signals in the γ-spectra, however, was found to increase in most cases (i.e. from about 10% to more than 20%) when Pd(NO 3 ) 2 , Pd(NO 3 ) 2 + Mg(NO 3 ) 2 , PdCl 2 , IrCl 3 , SnCl 2 , AgCl, NaF, NH 4 Cl and NH 4 F were added at amounts generally used in electrothermal vaporization inductively coupled plasma mass spectrometry. However, when adding higher amounts as stoichiometrically required for a complete halogenation of the sample matrix in the case of AgCl, C 8 F 15 O 2 Na, IrCl 3 or PdCl 2 the transport efficiencies considerably decrease again. As shown in the case of NH 4 Cl the amount of thermochemical reagent used has to be optimized so as to obtain maximum analyte transport efficiencies. A comparison of the influence of NH 4 Cl on the transport efficiencies with its influence on the ETV-ICP-MS signals for Fe demonstrates the importance of transport efficiency changes for the effects of thermochemical reagents in electrothermal vaporization inductively coupled plasma mass spectrometry

  12. Impact of Heat and Mass Transfer during the Transport of Nitrogen in Coal Porous Media on Coal Mine Fires

    OpenAIRE

    Shi, Bobo; Zhou, Fubao

    2014-01-01

    The application of liquid nitrogen injection is an important technique in the field of coal mine fire prevention. However, the mechanism of heat and mass transfer of cryogenic nitrogen in the goaf porous medium has not been well accessed. Hence, the implementation of fire prevention engineering of liquid nitrogen roughly relied on an empirical view. According to the research gap in this respect, an experimental study on the heat and mass transfer of liquid nitrogen in coal porous media was pr...

  13. PORFLO - a continuum model for fluid flow, heat transfer, and mass transport in porous media. Model theory, numerical methods, and computational tests

    International Nuclear Information System (INIS)

    Runchal, A.K.; Sagar, B.; Baca, R.G.; Kline, N.W.

    1985-09-01

    Postclosure performance assessment of the proposed high-level nuclear waste repository in flood basalts at Hanford requires that the processes of fluid flow, heat transfer, and mass transport be numerically modeled at appropriate space and time scales. A suite of computer models has been developed to meet this objective. The theory of one of these models, named PORFLO, is described in this report. Also presented are a discussion of the numerical techniques in the PORFLO computer code and a few computational test cases. Three two-dimensional equations, one each for fluid flow, heat transfer, and mass transport, are numerically solved in PORFLO. The governing equations are derived from the principle of conservation of mass, momentum, and energy in a stationary control volume that is assumed to contain a heterogeneous, anisotropic porous medium. Broad discrete features can be accommodated by specifying zones with distinct properties, or these can be included by defining an equivalent porous medium. The governing equations are parabolic differential equations that are coupled through time-varying parameters. Computational tests of the model are done by comparisons of simulation results with analytic solutions, with results from other independently developed numerical models, and with available laboratory and/or field data. In this report, in addition to the theory of the model, results from three test cases are discussed. A users' manual for the computer code resulting from this model has been prepared and is available as a separate document. 37 refs., 20 figs., 15 tabs

  14. Two-phase, mass-transport model for direct methanol fuel cells with effect of non-equilibrium evaporation and condensation

    Science.gov (United States)

    Yang, W. W.; Zhao, T. S.

    A two-phase, mass-transport model for liquid-feed direct methanol fuel cells (DMFCs) is developed by taking into account the effect of non-equilibrium evaporation and condensation of methanol and water. The comparison between the present model and other models indicates that the present model yields more reasonable predictions of cell performance. Particularly, it is shown that the models that invoke a thermodynamic-equilibrium assumption between phases will overestimate mass-transport rates of methanol and water, thereby resulting in an inaccurate prediction of cell performance. The parametric study using the present model reveals that the gas coverage at the flow channel-diffusion-layer interface is directly related to the gas-void fraction inside the anode porous region; increasing the gas-void fraction will increase the mass-transfer resistance of methanol and thus lower cell performance. The effects of the geometric dimensions of the cell structure, such as channel width and rib width, on cell performance are also investigated with the model developed in this work.

  15. Variability of Atmospheric Radon-222 and Secondary Aerosol Components in Accordance with Air Mass Transport Pathways at Jeju Island, Korea, during 2011-2014

    International Nuclear Information System (INIS)

    Bu, Jun-Oh; Song, Jung-Min; Kim, Won-Hyung; Kang, Chang-Hee; Chambers, Scott D.; Williams, Alastair G.; Lee, Chulkyu

    2016-01-01

    Real-time monitoring of hourly atmospheric Radon-222 concentration and three daily monitoring of the secondary aerosol components of PM_1_0 were performed throughout 2011-2014 at Gosan station, Jeju Island, in order to characterize their background levels and temporal variation. The annual mean radon and PM_1_0 mass concentrations were 2326 ± 1198 mBq/m"3 and 37.1 ± 19.5 μg/m"3, respectively. Based on cluster analyses of air mass back trajectories, the frequencies of air masses originating from continental Chi