WorldWideScience

Sample records for hydrogeochemical transport modeling

  1. HYDROGEOCHEM: A coupled model of HYDROlogic transport and GEOCHEMical equilibria in reactive multicomponent systems

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, G.T.; Tripathi, V.S.

    1990-11-01

    This report presents the development of a hydrogeochemical transport model for multicomponent systems. The model is designed for applications to proper hydrological setting, accommodation of complete suite of geochemical equilibrium processes, easy extension to deal with chemical kinetics, and least constraints of computer resources. The hydrological environment to which the model can be applied is the heterogeneous, anisotropic, saturated-unsaturated subsurface media under either transient or steady state flow conditions. The geochemical equilibrium processes included in the model are aqueous complexation, adsorption-desorption, ion exchange, precipitation-dissolution, redox, and acid-base reactions. To achieve the inclusion of the full complement of these geochemical processes, total analytical concentrations of all chemical components are chosen as the primary dependent variables in the hydrological transport equations. Attendant benefits of this choice are to make the extension of the model to deal with kinetics of adsorption-desorption, ion exchange, precipitation-dissolution, and redox relatively easy. To make the negative concentrations during the iteration between the hydrological transport and geochemical equilibrium least likely, an implicit form of transport equations are proposed. To alleviate severe constraints of computer resources in terms of central processing unit (CPU) time and CPU memory, various optional numerical schemes are incorporated in the model. The model consists of a hydrological transport module and geochemical equilibrium module. Both modules were thoroughly tested in code consistency and were found to yield plausible results. The model is verified with ten examples. 79 refs., 21 figs., 17 tabs.

  2. Users` manual for LEHGC: A Lagrangian-Eulerian Finite-Element Model of Hydrogeochemical Transport Through Saturated-Unsaturated Media. Version 1.1

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, Gour-Tsyh [Pennsylvania State Univ., University Park, PA (United States). Dept. of Civil and Environmental Engineering; Carpenter, S.L. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Earth and Planetary Sciences; Hopkins, P.L.; Siegel, M.D. [Sandia National Labs., Albuquerque, NM (United States)

    1995-11-01

    The computer program LEHGC is a Hybrid Lagrangian-Eulerian Finite-Element Model of HydroGeo-Chemical (LEHGC) Transport Through Saturated-Unsaturated Media. LEHGC iteratively solves two-dimensional transport and geochemical equilibrium equations and is a descendant of HYDROGEOCHEM, a strictly Eulerian finite-element reactive transport code. The hybrid Lagrangian-Eulerian scheme improves on the Eulerian scheme by allowing larger time steps to be used in the advection-dominant transport calculations. This causes less numerical dispersion and alleviates the problem of calculated negative concentrations at sharp concentration fronts. The code also is more computationally efficient than the strictly Eulerian version. LEHGC is designed for generic application to reactive transport problems associated with contaminant transport in subsurface media. Input to the program includes the geometry of the system, the spatial distribution of finite elements and nodes, the properties of the media, the potential chemical reactions, and the initial and boundary conditions. Output includes the spatial distribution of chemical element concentrations as a function of time and space and the chemical speciation at user-specified nodes. LEHGC Version 1.1 is a modification of LEHGC Version 1.0. The modification includes: (1) devising a tracking algorithm with the computational effort proportional to N where N is the number of computational grid nodes rather than N{sup 2} as in LEHGC Version 1.0, (2) including multiple adsorbing sites and multiple ion-exchange sites, (3) using four preconditioned conjugate gradient methods for the solution of matrix equations, and (4) providing a model for some features of solute transport by colloids.

  3. 3DHYDROGEOCHEM: A 3-DIMENSIONAL MODEL OF DENSITY-DEPENDENT SUBSURFACE FLOW AND THERMAL MULTISPECIES-MULTICOMPONENT HYDROGEOCHEMICAL TRANSPORT

    Science.gov (United States)

    This report presents a three-dimensional finite-element numerical model designed to simulate chemical transport in subsurface systems with temperature effect taken into account. The three-dimensional model is developed to provide (1) a tool of application, with which one is able...

  4. Application of hydrogeochemical modelling in simulating the transportation of elements in fly ash heap under different disposal systems in South Africa

    Science.gov (United States)

    Mbugua, J. M.; Ngila, J. C.; Kindness, A.; Demlie, M.

    Ash heap modelling of South African fly ash from Tutuka was carried out and the duration of transportation projected for 20 years based on two disposal scenarios, namely; irrigation of ash with rainwater, and irrigation with brines. The hydrogeochemical modeling code, PHREEQC, was applied in the study which gave insights into the speciation, release and transport of elements from the water and brines-fly ash long term interactions. Tutuka ash-water heap model showed a general sharp decrease of total elemental concentrations released during the first 2.5 years simulation as the pH value dropped from 12.6 to 8.7, after which it remained constant and their concentration remained constant up to 20 years. The elements showing this trend included Ca, Mg, Al, Fe, Sr, Zn, Na, K, Li and C(4). Generally, brines caused sharp increase in released concentration of the elements Ca, Mg, S(6) and C(4) for the first 3 years of heap irrigation whereas with water irrigation an opposite trend was observed in which the elemental concentrations decreased. Much of the release chemistry of the elements was closely related to the phase dissolution/precipitation and formation as the major controlling factors. Generally therefore, the modelled leachate quality results revealed that many elements are mobile and move through the ash heap in a progressive leaching pathway. The model could therefore be used to provide reasonable leachate quality from the modelled Tutuka ash heap which may be reaching the ground water. Overall, the ash heap modelling enhanced the understanding of the environmental impacts of ash-water-brines interactions and demonstrated that leachate composition is determined by the following factors; (i) the mass flows from the pores of fly ash, (ii) the surface dissolution of the mineral phases, (iii) the various chemical reactions involved during the ash-brine and ash-water interactions, (iv) the interactions with a gas phase (atmospheric CO2), (v) the composition of the

  5. Techniques to develop data for hydrogeochemical models

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, C.M.; Holcombe, L.J.; Gancarz, D.H.; Behl, A.E. (Radian Corp., Austin, TX (USA)); Erickson, J.R.; Star, I.; Waddell, R.K. (Geotrans, Inc., Boulder, CO (USA)); Fruchter, J.S. (Battelle Pacific Northwest Lab., Richland, WA (USA))

    1989-12-01

    The utility industry, through its research and development organization, the Electric Power Research Institute (EPRI), is developing the capability to evaluate potential migration of waste constitutents from utility disposal sites to the environment. These investigations have developed computer programs to predict leaching, transport, attenuation, and fate of inorganic chemicals. To predict solute transport at a site, the computer programs require data concerning the physical and chemical conditions that affect solute transport at the site. This manual provides a comprehensive view of the data requirements for computer programs that predict the fate of dissolved materials in the subsurface environment and describes techniques to measure or estimate these data. In this manual, basic concepts are described first and individual properties and their associated measurement or estimation techniques are described later. The first three sections review hydrologic and geochemical concepts, discuss data requirements for geohydrochemical computer programs, and describe the types of information the programs produce. The remaining sections define and/or describe the properties of interest for geohydrochemical modeling and summarize available technique to measure or estimate values for these properties. A glossary of terms associated with geohydrochemical modeling and an index are provided at the end of this manual. 318 refs., 9 figs., 66 tabs.

  6. 3DHYDROGEOCHEM: A 3-DIMENSIONAL MODEL OF DENSITY-DEPENDENT SUBSURFACE FLOW AND THERMAL MULTISPECIES-MULTICOMPONENT HYDROGEOCHEMICAL TRANSPORT (EPA/600/SR-98/159)

    Science.gov (United States)

    This report presents a three-dimensional finite-element numerical model designed to simulate chemical transport in subsurface systems with temperature effect taken into account. The three-dimensional model is developed to provide (1) a tool of application, with which one is able ...

  7. Hydrogeochemical modelling of geothermal systems in the Malm Aquifer

    Science.gov (United States)

    Baumann, Thomas; Ueckert, Martina

    2017-04-01

    The Malm sediments in the Bavarian Molasse Basin are very suitable for hydrogeothermal heat and energy production and for energy storage. With the conversion of the Pullach injection well to a production well it was possible to quantify the reactions in the reservoir and to validate the hydrogeochemical models. This data set was complemented by the results from a heat storage test. The calibrated hydrogeochemical model was used to predict and optimize the long term behaviour of geothermal doublets. In facilities using more than two wells, mixing ratios for the production wells were assessed and optimized. Most of the simulations showed a benign long-term behaviour, even in more complex systems. Dissolution of carbonates at the injection wells propagates into the reservoir and contributes to an increase of the injectivity. It also seems to be possible to make use of the gas load which is otherwise crucial to maintain to prevent the formation of scalings. The situation changes for geothermal heat storage systems, eg. a geothermal doublet in combination with a combined heat and power plant. The cyclic operation causes a significant increase of the carbonate concentrations. Consequently, the amount of eg. CO2 that has to be added to the water to prevent precipitation of carbonates during the heating cycle, has to increase as well. The simulation results show that a doublet system for heat storage reaches an unstable situation after a few cycles. These results are supported by the data form a heat storage test and by the data from the conversion of the Pullach well. The model also shows that long-term operation is possible in a triplet setup.

  8. New insight into unstable hillslopes hydrology from hydrogeochemical modelling.

    Science.gov (United States)

    Bertrand, C.; Marc, V.; Malet, J.-P.

    2010-05-01

    In the black marl outcrops of the French South Alps, sub surface flow conditions are considered as the main triggering factor for initiation and reactivation of landslides. The problem is traditionally addressed in term of hydrological processes (how does percolation to the water table occur?) but in some cases the origin of water is also in question. Direct rainfall is generally assumed as the only water source for groundwater recharge in shallow hillslope aquifers. The bedrock is also supposed impervious and continuous. Yet the geological environment of the study area is very complex owing to the geological history of this alpine sector. The autochthonous callovo-oxfordian black marl bedrock is highly tectonized (Maquaire et al., 2003) and may be affected by large, possibly draining discontinuities. A deep water inflow at the slip surface may at least locally result in increase the pore pressure and decrease the effective shearing resistance of the landslide material. In the active slow-moving landslide of Super-Sauze (Malet and Maquaire, 2003), this question has been addressed using hydrochemical investigations. The groundwater was sampled during five field campaigns uniformly spread out over the year from a network of boreholes. Water chemistry data were completed by geochemical and mineralogical analyses of the marl material. The major hydro-geochemical processes over area proved (1) mixing processes, (2) pyrite alteration, (3) dissolution/precipitation of carbonates and (4) cations exchange (de Montety et al., 2007). A geochemical modelling was carried out using the model Phreeqc (Parkhurst and Appelo, version 2.15, 2008) to check how suitable was observed water chemistry with the reservoir characteristics. The modelling exercise was based on a kinetics approach of soil-water interactions. The model simulates the rock alteration by the dissolution of the primary minerals and the precipitation of new phases. Initial parameters were obtained from geochemical

  9. The effects of physical and geochemical heterogeneities on hydro-geochemical transport and effective reaction rates

    Science.gov (United States)

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

    2014-09-01

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

  10. The effects of physical and geochemical heterogeneities on hydro-geochemical transport and effective reaction rates.

    Science.gov (United States)

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

    2014-09-01

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

  11. Hydrogeochemical modelling of seawater injection into offshore oil fields; Modellierung hydrogeochemischer Prozesse bei der Injektion von Meerwasser in Offshore-Oellagerstaetten

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Yunjiao; Berk, Wolfgang van [Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany). Abt. Hydrogeologie; Schulz, Hans-Martin [Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum (GFZ), Potsdam (Germany). Sek. 4.3 - Organische Geochemie

    2013-01-15

    Sea water is injected into offshore oilfields and coastal-near onshore fields to maintain pressure for secondary recovery. Due to compositional differences of sea water and formation water, hydrogeochemical processes are initiated. Such processes develop from the injection well along the migration path through the reservoir, and reach the production well. Ultimately, the mixing ratio of the two water types controls processes such as precipitation of minerals or dissolution of minerals from the reservoir rock. Here, we are introducing mass balance models based on chemical thermodynamics as a hydrogeochemical tool to qualitatively and quantitatively retrace such processes. It is the aim to demonstrate how mixing of sea and formation water controls type and amount of scaling and mineral dissolution, exemplarily in the UK Miller oilfield (North Sea). The presented approach and the results shall highlight the applicability of hydrogeochemical mass balance models in order to predict scale-forming processes. Finally, an outlook is presented about predictive hydrogeochemical 1D- and 3D-transport models in development. (orig.)

  12. Semi-supervised Machine Learning for Analysis of Hydrogeochemical Data and Models

    Science.gov (United States)

    Vesselinov, Velimir; O'Malley, Daniel; Alexandrov, Boian; Moore, Bryan

    2017-04-01

    Data- and model-based analyses such as uncertainty quantification, sensitivity analysis, and decision support using complex physics models with numerous model parameters and typically require a huge number of model evaluations (on order of 10^6). Furthermore, model simulations of complex physics may require substantial computational time. For example, accounting for simultaneously occurring physical processes such as fluid flow and biogeochemical reactions in heterogeneous porous medium may require several hours of wall-clock computational time. To address these issues, we have developed a novel methodology for semi-supervised machine learning based on Non-negative Matrix Factorization (NMF) coupled with customized k-means clustering. The algorithm allows for automated, robust Blind Source Separation (BSS) of groundwater types (contamination sources) based on model-free analyses of observed hydrogeochemical data. We have also developed reduced order modeling tools, which coupling support vector regression (SVR), genetic algorithms (GA) and artificial and convolutional neural network (ANN/CNN). SVR is applied to predict the model behavior within prior uncertainty ranges associated with the model parameters. ANN and CNN procedures are applied to upscale heterogeneity of the porous medium. In the upscaling process, fine-scale high-resolution models of heterogeneity are applied to inform coarse-resolution models which have improved computational efficiency while capturing the impact of fine-scale effects at the course scale of interest. These techniques are tested independently on a series of synthetic problems. We also present a decision analysis related to contaminant remediation where the developed reduced order models are applied to reproduce groundwater flow and contaminant transport in a synthetic heterogeneous aquifer. The tools are coded in Julia and are a part of the MADS high-performance computational framework (https://github.com/madsjulia/Mads.jl).

  13. Hydrogeochemical evaluation for Simpevarp model version 1.2. Preliminary site description of the Simpevarp area

    Energy Technology Data Exchange (ETDEWEB)

    Laaksoharju, Marcus (ed.) [Geopoint AB, Stockholm (Sweden)

    2004-12-01

    process. It controls chloride concentration that, in turn, determines the re-equilibrium path (water-rock interaction) triggered by mixing. Coupled transport modelling was used to model the groundwater age, tritium content and calcite dissolution/precipitation processes at shallow groundwater depths at both Laxemar and Simpevarp. The modelled results provide additional support to hydrogeological models by using independent hydrochemical information and added support to the general hydrogeochemical understanding of the site. In this evaluation the groundwater model has been updated, the salinity distribution, mixing processes and the major reactions altering the groundwaters have been modelled down to a depth of 1000 m, and an updated Hydrogeochemical Site Descriptive Model version 1.2 has been produced. More groundwater and isotopic data, together with microbial information, colloids and gases, provided additional site descriptive information. Finally, the introduction of coupled modelling provided additional possibilities to address independently the various processes in question.

  14. hydrogeochemical hydrogeochemical and biophysical

    African Journals Online (AJOL)

    eobe

    In situ measurements of temperature, pH, TDS, and EC were determined intrusively with appropriate probes. The Cat ions K+, Ca2+, Na2+ Mg2+ and heavy metals Zn,. Cu, Fe, Ba and Mn were determine using Atomic. Absorption Spectrometer (AAS) Model PYE Unicam SP. 2900. Other parameters were also determined by.

  15. Influence of Humic Acid on the Transport and Deposition of Colloidal Silica under Different Hydrogeochemical Conditions

    Directory of Open Access Journals (Sweden)

    Jingjing Zhou

    2016-12-01

    Full Text Available The transport and deposition of colloids in aquifers plays an important role in managed aquifer recharge (MAR schemes. Here, the processes of colloidal silica transport and deposition were studied by displacing groundwater with recharge water. The results showed that significant amounts of colloidal silica transport occurred when native groundwater was displaced by HA solution. Solution contains varying conditions of ionic strength and ion valence. The presence of humic acid could affect the zeta potential and size of the colloidal silica, which led to obvious colloidal silica aggregation in the divalent ion solution. Humic acid increased colloidal silica transport by formation of non-adsorbing aqueous phase silica–HA complexes. The experimental and modeling results showed good agreement, indicating that the essential physics were accurately captured by the model. The deposition rates were less than 10−8 s−1 in deionized water and monovalent ion solution. Moreover, the addition of Ca2+ and increase of IS resulted in the deposition rates increasing by five orders of magnitude to 10−4 s−1. In all experiments, the deposition rates decreased in the presence of humic acid. Overall, the promotion of humic acid in colloidal silica was strongly associated with changes in water quality, indicating that they should receive greater attention during MAR.

  16. Hydrogeochemical processes governing the origin, transport and fate of major and trace elements from mine wastes and mineralized rock to surface waters

    Science.gov (United States)

    Nordstrom, D. Kirk

    2011-01-01

    The formation of acid mine drainage from metals extraction or natural acid rock drainage and its mixing with surface waters is a complex process that depends on petrology and mineralogy, structural geology, geomorphology, surface-water hydrology, hydrogeology, climatology, microbiology, chemistry, and mining and mineral processing history. The concentrations of metals, metalloids, acidity, alkalinity, Cl-, F- and SO42- found in receiving streams, rivers, and lakes are affected by all of these factors and their interactions. Remediation of mine sites is an engineering concern but to design a remediation plan without understanding the hydrogeochemical processes of contaminant mobilization can lead to ineffective and excessively costly remediation. Furthermore, remediation needs a goal commensurate with natural background conditions rather than water-quality standards that might bear little relation to conditions of a highly mineralized terrain. This paper reviews hydrogeochemical generalizations, primarily from US Geological Survey research, that enhance our understanding of the origin, transport, and fate of contaminants released from mined and mineralized areas.

  17. Hydrogeochemical processes and geochemical modeling in a coastal aquifer: Case study of the Marathon coastal plain, Greece

    Science.gov (United States)

    Papazotos, Panagiotis; Koumantakis, Ioannis; Kallioras, Andreas; Vasileiou, Eleni; Perraki, Maria

    2017-04-01

    Determining the hydrogeochemical processes has always been a challenge for scientists. The aim of this work is the study of the principal hydrogeochemical processes controlling groundwater quality in the Marathon coastal plain, Greece, with emphasis on the origin of the solutes. Various physicochemical parameters and major ions of twenty-five groundwater samples were analyzed. The hydrogeochemical data of groundwater were studied in order to determine the major factors controlling the chemical composition and hydrogeochemical evolution. In the Marathon coastal plain, three different zones of the alluvial granular aquifer system have been detected, considering the geochemical processes and recharge, which affect its hydrochemical characteristics. The alluvial granular aquifer system is divided eastwards into three zones: a) the natural recharge zone, b) the reverse ion exchange zone and c) the diffusion sea water zone. Cl-is the dominant anion and Na+and Ca2+ are the dominant cations, as determined by plotting the analyses on the respective Piper diagram. Near the coastline high concentrations of Na+ and Cl- were observed indicating a zone of seawater intrusion. On the other hand, westward there is increasing concentration of HCO3- with simultaneous decrease of Na+is indication of a recharge zone from karstic aquifers of the study area. Between the aforementioned zones there is an intermediate one, where reverse ion exchange takes place due to high concentrations of dissolved Na+ and Ca2+ adsorption. The saturation indices (SI) were calculated using the geochemical modeling software PHREEQC. Mineral phases of halite, sylvite, gypsum and anhydrite were estimated to be undersaturated in the water samples, suggesting these phases are minor or absent in the host rock. On the other hand, calcite, aragonite and dolomite are close to equilibrium; these minerals are present in the host rocks or in the unsaturated zone, possibly increasing the Ca2+, Mg2+ and HCO3

  18. Hydrogeochemical evaluation of the Simpevarp area, model version 1.1

    Energy Technology Data Exchange (ETDEWEB)

    Laaksoharju, Marcus (ed.) [Geopoint AB, Stockholm (Sweden); Smellie, John [Conterra AB, Uppsala (Sweden); Gimeno, Maria; Auque, Luis; Gomez, Javier [Univ. of Zaragoza (Spain). Dept. of Earth Sciences; Tullborg, Eva-Lena [Terralogica AB, Graabo (Sweden); Gurban, Ioana [3D-Terra (Sweden)

    2004-02-01

    Siting studies for SKB's programme of deep geological disposal of nuclear fuel waste currently involves the investigation of two locations, Simpevarp and Forsmark, on the eastern coast of Sweden to determine their geological, hydrogeochemical and hydrogeological characteristics. Present work completed has resulted in model version 1.1 which represents the first evaluation of the available Simpevarp groundwater analytical data collected up to July 1st, 2003 (i.e. the first 'data freeze' of the site). The HAG (Hydrochemical Analytical Group) group had access to a total of 535 water samples collected from the surface and sub-surface environment (e.g. soil pipes in the overburden, streams and lakes); only a few samples were collected from drilled boreholes. The deepest fracture groundwater samples with sufficient analytical data reflected depths down to 250 m. Furthermore, most of the waters sampled (79%) lacked crucial analytical information that restricted the evaluation. Consequently, model version 1.1 focussed on the processes taking place in the uppermost part of the bedrock rather than at repository levels. The complex groundwater evolution and patterns at Simpevarp are a result of many factors such as: a) the flat topography and proximity to the Baltic Sea, b) changes in hydrogeology related to glaciation/deglaciation and land uplift, c) repeated marine/lake water regressions/transgressions, and d) organic or inorganic alteration of the groundwater composition caused by microbial processes or water/rock interactions. The sampled groundwaters reflect to various degrees of modern or ancient water/rock interactions and mixing processes. Higher topography to the west of Simpevarp has resulted in hydraulic gradients which have partially flushed out old water types. Except for sea waters, most surface waters and some groundwaters from percussion boreholes are fresh, non-saline waters according to the classification used for Aespoe groundwaters. The rest

  19. Hydrogeochemical evaluation of the Forsmark site, model version 1.1

    Energy Technology Data Exchange (ETDEWEB)

    Laaksoharju, Marcus (ed.) [GeoPoint AB, Sollentuna (Sweden); Gimeno, Maria; Auque, Luis; Gomez, Javier [Univ. of Zaragoza (Spain). Dept. of Earth Sciences; Smellie, John [Conterra AB, Uppsala (Sweden); Tullborg, Eva-Lena [Terralogica AB, Graabo (Sweden); Gurban, Ioana [3D-Terra, Montreal (Canada)

    2004-01-01

    values below detection limit). The meteoric water is found at the surface and at shallow depths and the marine water is found closer to the coast and at depths affected by Baltic Sea water and probably old Litorina Sea water. The present state of knowledge of the reactive system is that the main water-rock interaction processes that affects the chemistry in the fresh meteoric waters are: 1) decomposition of organic matter, 2) calcite, plagioclase, biotite and sulphide dissolution, 3) Na-Ca ion exchange, and 4) phyllosilicate precipitation probably extremely slow in the present environment. For the brackish-saline groundwaters in contrast, the water/rock interaction processes seem to be less important although this has not been established because of a lack of data. At the moment multiple end-member mixing between marine water, glacial melt water and a deeper saline water seem to play a significant role. Based on presently available data, the groundwater sample at 115 m depth, i.e. not representative of repository depths, met the groundwater criterion established by SKB concerning the measured Eh, pH, TDS and Ca+Mg values. The redox system at this depth is controlled by the presence of iron oxides, hydroxides or by sulphide minerals. In this evaluation the post glacial groundwater scenario model has been updated, the salinity distribution, mixing processes and the major reactions altering the groundwaters have been modelled down to a depth of 200 m and a new Hydrogeochemical Site Descriptive Model version 1.1 has been produced. A 3D groundwater description of the site was not produced at this stage due to a lack of observations reflecting spatial variations. The possibilities to compare and integrate future hydrochemical modelling with hydrogeological modelling has improved due to major development in constructing hydrogeological site models. The salinity distribution in fractures and the rock matrix together with mixing proportions can be compared from two independent

  20. Geochemical tracing and hydrogeochemical modelling of water-rock interactions during salinization of alluvial groundwater (Upper Rhine Valley, France)

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, Y., E-mail: yann.lucas@eost.u-strasbg.fr [Universite de Strasbourg et CNRS, Laboratoire d' Hydrologie et de Geochimie de Strasbourg, Ecole et Observatoire des Sciences de la Terre, 1, rue Blessig, 67084 Strasbourg Cedex (France); Schmitt, A.D., E-mail: anne-desiree.schmitt@univ-fcomte.fr [Universite de Strasbourg et CNRS, Laboratoire d' Hydrologie et de Geochimie de Strasbourg, Ecole et Observatoire des Sciences de la Terre, 1, rue Blessig, 67084 Strasbourg Cedex (France)] [Universite de Franche-Comte et CNRS-UMR 6249, Chrono-Environnement, 16, Route de Gray, 25030 Besancon Cedex (France); Chabaux, F., E-mail: francois.chabaux@eost.u-strasbg.fr [Universite de Strasbourg et CNRS, Laboratoire d' Hydrologie et de Geochimie de Strasbourg, Ecole et Observatoire des Sciences de la Terre, 1, rue Blessig, 67084 Strasbourg Cedex (France); Clement, A.; Fritz, B. [Universite de Strasbourg et CNRS, Laboratoire d' Hydrologie et de Geochimie de Strasbourg, Ecole et Observatoire des Sciences de la Terre, 1, rue Blessig, 67084 Strasbourg Cedex (France); Elsass, Ph. [BRGM, GEODERIS, 1, rue Claude Chappe, 57070 Metz (France); Durand, S. [Universite de Strasbourg et CNRS, Laboratoire d' Hydrologie et de Geochimie de Strasbourg, Ecole et Observatoire des Sciences de la Terre, 1, rue Blessig, 67084 Strasbourg Cedex (France)

    2010-11-15

    Research highlights: {yields} Major and trace elements along with strontium and uranium isotopic ratios show that groundwater geochemical characteristics along the saline plumes cannot reflect a conservative mixing. {yields} A coupled hydrogeochemical model demonstrates that cationic exchange between alkalis from polluted waters and alkaline-earth elements from montmorillonite present in the host rock of the aquifer is the primary process. {yields} The model requires only a small amount of montmorillonite. {yields} It is necessary to consider the pollution history to explain the important chloride, sodium and calcium concentration modifications. {yields} The model shows that the rapidity of the cationic exchange reactions insures a reversibility of the cation fixation on clays in the aquifer. - Abstract: In the southern Upper Rhine Valley, groundwater has undergone intensive saline pollution caused by the infiltration of mining brines, a consequence of potash extraction carried out during the 20th century. Major and trace elements along with Sr and U isotopic ratios show that groundwater geochemical characteristics along the saline plumes cannot reflect conservative mixing between saline waters resulting from the dissolution of waste heaps and one or more unpolluted end-members. The results imply the occurrence of interactions between host rocks and polluted waters, and they suggest that cationic exchange mechanisms are the primary controlling process. A coupled hydrogeochemical model has been developed with the numerical code KIRMAT, which demonstrates that cationic exchange between alkalis from polluted waters and alkaline-earth elements from montmorillonite present in the host rock of the aquifer is the primary process controlling the geochemical evolution of the groundwater. The model requires only a small amount of montmorillonite (between 0.75% and 2.25%), which is in agreement with the observed mineralogical composition of the aquifer. The model also proves

  1. Earthquakes: hydrogeochemical precursors

    Science.gov (United States)

    Ingebritsen, Steven E.; Manga, Michael

    2014-01-01

    Earthquake prediction is a long-sought goal. Changes in groundwater chemistry before earthquakes in Iceland highlight a potential hydrogeochemical precursor, but such signals must be evaluated in the context of long-term, multiparametric data sets.

  2. Hydrogeochemical characteristics of water intakes from groundwater sources in Seversk

    Science.gov (United States)

    Karmalov, A. I.; Dutova, E. M.; Vologdina, I. V.; Pokrovsky, D. S.; Pokrovskiy, V. D.; Kuzevanov, K. K.

    2016-09-01

    The article describes the hydrogeochemical environment behavior analysis of groundwater intake which, in its turn. provides the utility and drinking water supply for Seversk. The reasons for temporary changes of the hydrogeochemical aquifer indicators in the producing areas have been highlighted. The main factor could be upset hydrodynamic conditions during long-term operation. Changed hydrogeochemical indicators have been revealed not only during the technological water treatment process but also during water transportation to consumers. Chemical composition water changes are related to secondary mineral and sludge formation on technological equipment. Precipitation is a polymineral mixture predominantly a ferrous phase. whereas phosphate and carbonate phases are secondary. Clay minerals are also found.

  3. Hydro-geochemical paths of multi-layer groundwater system in coal mining regions - Using multivariate statistics and geochemical modeling approaches.

    Science.gov (United States)

    Liu, Pu; Hoth, Nils; Drebenstedt, Carsten; Sun, Yajun; Xu, Zhimin

    2017-12-01

    Groundwater is an important drinking water resource that requires protection in North China. Coal mining industry in the area may influence the water quality evolution. To provide primary characterization of the hydrogeochemical processes and paths that control the water quality evolution, a complex multi-layer groundwater system in a coal mining area is investigated. Multivariate statistical methods involving hierarchical cluster analysis (HCA) and principal component analysis (PCA) are applied, 6 zones and 3 new principal components are classified as major reaction zones and reaction factors. By integrating HCA and PCA with hydrogeochemical correlations analysis, potential phases, reactions and connections between various zones are presented. Carbonates minerals, gypsum, clay minerals as well as atmosphere gases - CO 2 , H 2 O and NH 3 are recognized as major reactants. Mixtures, evaporation, dissolution/precipitation of minerals and cation exchange are potential reactions. Inverse modeling is finally used, and it verifies the detailed processes and diverse paths. Consequently, 4 major paths are found controlling the variations of groundwater chemical properties. Shallow and deep groundwater is connected primarily by the flow of deep groundwater up through fractures and faults into the shallow aquifers. Mining does not impact the underlying aquifers that represent the most critical groundwater resource. But controls should be taken to block the mixing processes from highly polluted mine water. The paper highlights the complex hydrogeochemical evolution of a multi-layer groundwater system under mining impact, which could be applied to further groundwater quality management in the study area, as well as most of the other coalfields in North China. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Groundwater hydrogeochemical characteristics in rehabilitated coalmine spoils

    Science.gov (United States)

    Gomo, M.; Masemola, E.

    2016-04-01

    The investigation aims to identify and describe hydrogeochemical processes controlling the evolution of groundwater chemistry in rehabilitated coalmine spoils and their overall influence on groundwater quality at a study area located in the Karoo basin of South Africa. A good understanding of the processes that controls the evolution of the mine water quality is vital for the planning, application and management of post-mining remedial actions. The study utilises scatter plots, statistical analysis, PHREEQC hydrogeochemical modelling, stoichiometric reaction ratios analysis, and the expanded Durov diagram as complimentary tools to interpret the groundwater chemistry data collected from monitoring boreholes from 1995 to 2014. Measured pH ranging between 6-8 and arithmetic mean of 7.32 shows that the groundwater system is characterised by circumneutral hydrogeochemical conditions period. Comparison of measured groundwater ion concentrations to theoretical reaction stoichiometry identifies Dolomite-Acid Mine Drainage (AMD) neutralisation as the main hydrogeochemical process controlling the evolution of the groundwater chemistry. Hydrogeochemical modelling shows that, the groundwater has temporal variations of calcite and dolomite saturation indices characterised by alternating cycles of over-saturation and under-saturation that is driven by the release of sulphate, calcium and magnesium ions from the carbonate-AMD neutralization process. Arithmetic mean concentrations of sulphate, calcium and magnesium are in the order of 762 mg/L, 141 mg/L and 108 mg/L. Calcium and magnesium ions contribute to very hard groundwater quality conditions. Classification based on total dissolved solids (TDS), shows the circumneutral water is of poor to unacceptable quality for drinking purposes. Despite its ability to prevent AMD formation and leaching of metals, the dolomite-AMD neutralisation process can still lead to problems of elevated TDS and hardness which mines should be aware of

  5. Assessment and modeling of the groundwater hydrogeochemical quality parameters via geostatistical approaches

    Science.gov (United States)

    Karami, Shawgar; Madani, Hassan; Katibeh, Homayoon; Fatehi Marj, Ahmad

    2018-03-01

    Geostatistical methods are one of the advanced techniques used for interpolation of groundwater quality data. The results obtained from geostatistics will be useful for decision makers to adopt suitable remedial measures to protect the quality of groundwater sources. Data used in this study were collected from 78 wells in Varamin plain aquifer located in southeast of Tehran, Iran, in 2013. Ordinary kriging method was used in this study to evaluate groundwater quality parameters. According to what has been mentioned in this paper, seven main quality parameters (i.e. total dissolved solids (TDS), sodium adsorption ratio (SAR), electrical conductivity (EC), sodium (Na+), total hardness (TH), chloride (Cl-) and sulfate (SO4 2-)), have been analyzed and interpreted by statistical and geostatistical methods. After data normalization by Nscore method in WinGslib software, variography as a geostatistical tool to define spatial regression was compiled and experimental variograms were plotted by GS+ software. Then, the best theoretical model was fitted to each variogram based on the minimum RSS. Cross validation method was used to determine the accuracy of the estimated data. Eventually, estimation maps of groundwater quality were prepared in WinGslib software and estimation variance map and estimation error map were presented to evaluate the quality of estimation in each estimated point. Results showed that kriging method is more accurate than the traditional interpolation methods.

  6. Background complementary hydrogeochemical studies. SDM-Site Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Kalinowski, Birgitta E. (ed.)

    2008-08-15

    The overall objectives of the hydrogeochemical description for Forsmark are to establish a detailed understanding of the hydrogeochemical conditions at the site and to develop models that fulfil the needs identified by the safety assessment groups during the site investigation phase. Issues of concern to safety assessment are radionuclide transport and technical barrier behaviour, both of which are dependent on the chemistry of groundwater and pore water and their evolution with time. The work has involved the development of descriptive and mathematical models for groundwaters in relation to rock domains, fracture domains and deformation zones. Past climate changes are one of the major driving forces for hydrogeochemical changes and therefore of fundamental importance for understanding the palaeohydrogeological, palaeohydrogeochemical and present evolution of groundwater in the crystalline bedrock of the Fennoscandian Shield. Understanding current undisturbed hydrochemical conditions at the proposed repository site is important when predicting future changes in groundwater chemistry. The causes of copper corrosion and/or bentonite degradation are of particular interest as they may jeopardise the long-term integrity of the planned SKB repository system. Thus, the following variables are considered for the hydrogeochemical site descriptive modelling: pH, Eh, sulphur species, iron, manganese, uranium, carbonate, phosphate, nitrogen species, total dissolved solids (TDS), isotopes, colloids, fulvic and humic acids and microorganisms. In addition, dissolved gases (e.g. carbon dioxide, methane and hydrogen) are of interest because of their likely participation in microbial reactions. In this series of reports, the final hydrogeochemical evaluation work of the site investigation at the Forsmark site, is presented. The work was conducted by SKB's hydrogeochemical project group, ChemNet, which consists of independent consultants and university researchers with expertise

  7. Modelagua, a new interactive program of inverse mass-balance model for hydrogeochemical studies -- an example of its application in Aguascalientes, Mexico

    Science.gov (United States)

    Gonzalez, P.; Fagundo, J.; Fagundo, R.; Suárez, M.; Melian, C.; Cortes, A.; Ramos, J. A.

    2003-04-01

    The geochemical models consists on the application of physical-chemical principles to the interpretation of hydrogeochemical systems. This methodology has been developed according to two approaches: a) the inverse one, mass-balance, that uses a well-known data of the chemical composition of the water and the rock with the objective of identifying in a quantitative way the geochemical reactions that give origin to this composition, and b) the direct one that in the basis of some well-known initial conditions of the water-rock system, it predicts the characteristics of the resulting solution of the performance of hypothetical chemical reactions. With the reference of interactive programs such as BALANCE and NETPATH, for modelling net geochemical mass-balance reactions between an initial and final water along a hydrologic flow path, which also computes the mixing proportion of two initial waters and net geochemical reactions that can account for the observed composition of a final water, an interactive program of inverse model has been developed (MODELAGUA) that not only allow starting from well-known data of the chemical composition of the water and the rock to identify in a quantitative way the geochemical reactions that give origin to this composition, but allow to do analysis of mixture of waters and net geochemical reactions that can account for the observed composition of a final water, making use of natural tracer whose geochemical behavior allows them to be used as conservative ions. In this work is presented MODELAGUA, as a new interactive program of inverse model mass-balance and an example in Aguascalientes, Mexico of its application.

  8. SR-Site - hydrogeochemical evolution of the Forsmark site

    Energy Technology Data Exchange (ETDEWEB)

    Salas, Joaquin; Molinero, Jorge; Juarez, Iker (Amphos 21 (Spain)); Gimeno, Maria Jose; Auque, Luis; Gomez, Javier (Univ. of Zaragoza (Spain))

    2010-12-15

    The present work has involved the development of a methodology in order to simulate the evolution of the groundwater composition within the candidate repository site of the Forsmark area. A series of climate periods is expected to be probable after the repository closure (temperate, periglacial and glacial) and, eventually, the area could be submerged under seawaters or under a lake of glacial melt waters. These environmental conditions will affect groundwater flow and composition around of the candidate repository volume. The present report summarizes the results obtained by the calculations which reproduce the hydrogeochemical evolution in the Forsmark area, and within the candidate repository volume. The hydrogeochemical evolution of groundwaters is one of the key factors affecting the chemical stability of the buffer and the canister. In this way, the main objective of the hydrogeochemical simulations is to assay the evolution of a series of safety assessment factors, such as salinity, redox potential, pH, and concentrations of iron, sulphide and potassium, among others. Using ConnectFlow, previous hydrological calculations have provided the transport of (1) the fractions of selected reference waters (Deep Saline, Old Meteoric, Glacial, Littorina and Altered Meteoric groundwaters), or (2) salinities, depending on the working team (Serco or Terrasolve). The results of the regional-scale groundwater flow modelling for each specific climate period are used as input of the geochemical models. Groundwater compositions have been modelled using PHREEQC, through mixing and chemical reactions between the waters obtained from the hydrogeological models and the reactive fracture-filling minerals. Both models (hydrological and geochemical) are not fully coupled, and it allows a description of the geochemical heterogeneity, which otherwise would be hard to attain. The stage of the open repository has been non-numerically analysed. Aspects as salinity, redox conditions

  9. Hydro-geochemical modeling of the spatial and the temporal geochemical variations of the granitic Strengbach catchment springs (Vosges massif, France)

    Science.gov (United States)

    Ackerer, Julien; Chabaux, François; Lucas, Yann; Pierret, Marie Claire; Viville, Daniel; Fritz, Bertrand; Clement, Alain; Beaulieu, Emilie; Negrel, Philippe

    2017-04-01

    Regular analysis of the major element concentrations in waters from springs emerging on the Strengbach catchment is made for more than 20 years (OHGE, Observatoire Hydro-Géochimique de l'Environnement). These data confirm the spatial variability of geochemical characteristics of the Strengbach springs linked, at least partly, to the lithological variability of the substratum (Pierret et al., 2014). The data also indicate that at the first order, the geochemical fluxes exported from each spring are mainly linked to the spring discharges, without significant variations of the relationships linking these two parameters between 1990 and 2010. There is also no observation of significant variations for the dissolved silica and for most of the cationic concentrations with time. Only a significant decrease of the Ca concentrations is observed for the Strengbach springs from 1990 to 2010. Numerical simulations, performed with the KIRMAT hydro-geochemical code, show that such a decrease can be considered as the response in the "bedrock" of the water-rock interactions to the variations of the soil solution chemical compositions recorded over the last 20 years, marked by a significant increase of pH and decrease of Ca concentrations. In particular, the modeling results show that the Ca concentration decrease is controlled by the couple apatite/clays, and that significant modifications of the apatite dissolution rate and clay compositions occurred between 1990 and 2010. This study shows that the temporal evolution of the Strengbach spring chemistry cannot be explained by the only variations of the clay mineral compositions, i.e. a modification of the chemical composition of the precipitated clays or a modification of the ionic exchange capacity of the clay minerals, but that it is definitely the interrelations between the apatite and the clay minerals that are involved.

  10. Modeling Transport Layer Protocols

    Science.gov (United States)

    Sasnauskas, Raimondas; Weingaertner, Elias

    In a layered communication architecture, transport layer protocols handle the data exchange between processes on different hosts over potentially lossy communication channels. Typically, transport layer protocols are either connection-oriented or are based on the transmission of individual datagrams. Well known transport protocols are the connection-oriented Transmission Control Protocol (TCP) [372] and the User Datagram Protocol (UDP) [370] as well as the Stream Control Transmission Protocol (SCTP) [340] and DCCP, the Datagram Congestion Control Protocol [259]. In this chapter, we focus on the modeling process of the transport layer. While we mostly use TCP and UDP as a base of comparison from this point, we emphasize that the methodologies discussed further on are conferrable to virtually any transport layer in any layered communication architecture.

  11. Community Sediment Transport Model

    Science.gov (United States)

    2007-01-01

    with IKONOS imagery). The tidal-residual circulation (arrows, right panel) in the CSTM simulations generates sediment transport consistent with...method for estimating surface sediment concentrations from AVHRR using the method described in Myint and Walker (2002). Water quality parameters for...frequencies. A model with a spectral wave driver has a better convergence rate than a monochromatic wave driver. Optimized coupling frequencies are

  12. Reactive transport modeling of trichloroethene treatment with declining reactivity of iron.

    Science.gov (United States)

    Jeen, Sung-Wook; Mayer, K Ulrich; Gillham, Robert W; Blowes, David W

    2007-02-15

    Evolving reactivity of iron, resulting from precipitation of secondary minerals within iron permeable reactive barriers (PRBs), was included in a reactive transport model for trichloroethene (TCE) treatment. The accumulation of secondary minerals and reactivity loss were coupled using an empirically derived relationship that was incorporated into an existing multicomponent reactive transport code (MIN3P) by modifying the kinetic expressions. The simulation results were compared to the observations from long-term column experiments, which were designed to assess the effects of carbonate mineral formation on the performance of iron for TCE treatment. The model successfully reproduced the evolution of iron reactivity and the dynamic changes in geochemical conditions and contaminant treatment. Predictions under various hydrogeochemical conditions showed that TCE would be treated effectively for an extended period of time without a significant loss of permeability. Although there are improvements yet to be made, this study provides a significant advance in our ability to predict long-term performance of iron PRBs.

  13. Groupage Cargo Transportation Model

    Directory of Open Access Journals (Sweden)

    Aleksejevs Ruslans

    2016-03-01

    Full Text Available In this work we consider a specific problem of optimal planning of maritime transportation of multiproduct cargo by ships of one (corporate strategy or several (partially corporate strategy companies: the core of the problem consists of the existence of the network of intermediate seaports (i.e. transitional seaports, where for every ship arrived the cargo handling is done, and which are situated between the starting and the finishing seaports. In this work, there are mathematical models built from scratch in the form of multicriteria optimization problem; then the goal attainment method of Gembicki is used for reducing the built models to a one-criterion problem of linear programming.

  14. Hydrogeochemical Evolution of the Laxemar Site

    Energy Technology Data Exchange (ETDEWEB)

    Gimeno, Maria J.; Auque, Luis F.; Gomez, Javier B. (Univ. of Zaragoza (Spain)); Salas, Joaquin; Molinero, Jorge (Amphos 21, Barcelona (Spain))

    2010-11-15

    induce changes in the geochemical composition of groundwater around the repository. In this way, the present report summarizes the results obtained by the geochemical simulations performed to simulate the hydrogeochemical evolution of groundwaters in the Laxemar area. In the safety assessment of the candidate repository site, a series of functions and parameters must be evaluated. From a geochemical point of view, the most important are redox properties, pH and concentration of solutes. Other factors to be considered are the groundwater content of potassium, sulphide and iron, as they might affect the chemical stability of the buffer and the canister. Additionally, the effects of grouting in the geosphere and cement materials in the engineered barriers could affect groundwater's pH. Discussions of the results will be focused on these aspects. The starting point of the geochemical calculations is a series of hydrological models (using ConnectFlow and DarcyTools), which, based on the understanding of the palaeohydrogeological history of the sites (which assumes the presence of different water mixing events due to the input of different reference waters over the time), have provided information on (1) the transport of fractions of selected reference waters (deep saline, old meteoric, glacial, marine and present meteoric waters), in the case of the temperate period, or (2) the transport of salts, in the case of the glacial cycle. In the latter case, the rock volume initially contains a mixture of two reference waters: a deep saline groundwater and a dilute water from meteoric origin. The proportion of these two waters can be obtained from the salinity at any point in the rock volume. With the advancement and retreat of the glacier, the proportion of a third mixing end-member is calculated from the decrease of salinity at any point in the rock volume (a newly incoming glacial melt-water), changing the proportions of the other two reference waters correspondingly. Finally

  15. Transport hub flow modelling

    OpenAIRE

    Despagne, Wilfried; Frenod, Emmanuel

    2014-01-01

    Purpose: The purpose of this paper is to investigate the road freight haulage activity. Using the physical and data flow information from a freight forwarder, we intend to model the flow of inbound and outbound goods in a freight transport hub. Approach: This paper presents the operation of a road haulage group. To deliver goods within two days to any location in France, a haulage contractor needs to be part of a network. This network handles the processing of both physical goods and data. We...

  16. A field-scale reactive transport model for U(VI) migration influenced by coupled multirate mass transfer and surface complexation reactions

    Science.gov (United States)

    Ma, R.; Zheng, C.; Prommer, H.; Greskowiak, J.; Liu, C.; Zachara, J.; Rockhold, M.

    2010-05-01

    This study explores field-scale modeling of U(VI) reactive transport through incorporation of laboratory and field data. A field-scale reactive transport model was developed on the basis of laboratory-characterized U(VI) surface complexation reactions (SCRs) and multirate mass transfer processes, as well as field-measured hydrogeochemical conditions at the U.S. Department of Energy, Hanford 300 Area (300 A), Washington. The model was used to assess the importance of multirate mass transfer processes on U(VI) reactive transport and to evaluate the effect of variable geochemical conditions caused by dynamic river water-groundwater interactions on U(VI) plume migration. Model simulations revealed complex spatiotemporal relationships between groundwater composition and U(VI) speciation, adsorption, and plume migration. In general, river water intrusion enhances uranium adsorption and lowers aqueous uranium concentration because river water dilution increases pH and decreases aqueous bicarbonate concentration, leading to overall enhanced U(VI) surface complexation. Strong U(VI) retardation was computed for the field-measured hydrogeochemical conditions, suggesting a slow dissipation of the U(VI) plume, a phenomenon consistent with field observations. The simulations also showed that SCR-retarded U(VI) migration becomes more dynamic and synchronous with the groundwater flow field when multirate mass transfer processes are involved. Breakthrough curves at selected locations and the temporal changes in the calculated mass during the 20 year simulation period indicated that uranium adsorption/desorption never attained steady state because of the dynamic flow field and groundwater composition variations caused by river water intrusion. Thus, the multirate SCR model appears to be a crucial consideration for future reactive transport simulations of uranium contaminants at the Hanford 300 A site and elsewhere under similar hydrogeochemical conditions.

  17. identification of hydrogeochemical processes in groundwater using ...

    African Journals Online (AJOL)

    PROF EKWUEME

    GROUNDWATER USING MAJOR ION CHEMISTRY: A CASE STUDY. OF YENAGOA ... chemistry of the groundwater and identify the dominant hydrogeochemical processes and mechanisms responsible for the evolution of ... from silicate weathering process which was also supported by higher HCO3 values. Reverse ion ...

  18. Hydrogeochemical assessment of groundwater in Kashmir Valley ...

    Indian Academy of Sciences (India)

    Ca–HCO3, Mg–HCO3, Ca–Mg–HCO3, Na–HCO3 were the dominant hydrogeochemical facies. High concentration of HCO3 and pH less than 8.8 clearly indicated that intense chemical weathering processes have taken place in the study area. The groundwater flow pattern in the area follows the local surface topography ...

  19. Hydrogeochemical analysis and quality evaluation of groundwater ...

    African Journals Online (AJOL)

    GREG

    2013-05-08

    May 8, 2013 ... hydrogeochemical parameters were evaluated, while techniques such as sodium absorption ratio. (SAR), sodium percent, residual sodium ... water chemistry also has a potential use for tracing the origins and the history of water as well ... are especially subject to this action. It is hoped that this study would ...

  20. Hydrogeochemical framework and factor analysis of fluoride ...

    African Journals Online (AJOL)

    Fluoride contamination of groundwater within the Savelugu-Nanton District was assessed using hydrogeochemical framework and multivariate statistical approach. Eighty-one (No) boreholes were sampled for quality assessment in May and June 2008. The main objective of this study was to assess the fluoride levels in ...

  1. Hydrogeochemical analysis and quality evaluation of groundwater ...

    African Journals Online (AJOL)

    A total of 20 groundwater samples from boreholes and hand dug wells withinOnicha-Uburu and its environs were assessed to determine their suitability for irrigation purposes. Physical and hydrogeochemical parameters were evaluated, while techniques such as sodium absorption ratio (SAR), sodium percent, residual ...

  2. Consideration of transport logistics hubs in freight transport demand models

    National Research Council Canada - National Science Library

    Huber, Stefan; Klauenberg, Jens; Thaller, Carina

    2015-01-01

    The increasing importance of logistics and its effects on transportation processes have been considered in freight transport demand modelling by new model developments incorporating several logistics aspects...

  3. Stochastic models of intracellular transport

    Science.gov (United States)

    Bressloff, Paul C.; Newby, Jay M.

    2013-01-01

    The interior of a living cell is a crowded, heterogenuous, fluctuating environment. Hence, a major challenge in modeling intracellular transport is to analyze stochastic processes within complex environments. Broadly speaking, there are two basic mechanisms for intracellular transport: passive diffusion and motor-driven active transport. Diffusive transport can be formulated in terms of the motion of an overdamped Brownian particle. On the other hand, active transport requires chemical energy, usually in the form of adenosine triphosphate hydrolysis, and can be direction specific, allowing biomolecules to be transported long distances; this is particularly important in neurons due to their complex geometry. In this review a wide range of analytical methods and models of intracellular transport is presented. In the case of diffusive transport, narrow escape problems, diffusion to a small target, confined and single-file diffusion, homogenization theory, and fractional diffusion are considered. In the case of active transport, Brownian ratchets, random walk models, exclusion processes, random intermittent search processes, quasi-steady-state reduction methods, and mean-field approximations are considered. Applications include receptor trafficking, axonal transport, membrane diffusion, nuclear transport, protein-DNA interactions, virus trafficking, and the self-organization of subcellular structures.

  4. Stochastic models of intracellular transport

    KAUST Repository

    Bressloff, Paul C.

    2013-01-09

    The interior of a living cell is a crowded, heterogenuous, fluctuating environment. Hence, a major challenge in modeling intracellular transport is to analyze stochastic processes within complex environments. Broadly speaking, there are two basic mechanisms for intracellular transport: passive diffusion and motor-driven active transport. Diffusive transport can be formulated in terms of the motion of an overdamped Brownian particle. On the other hand, active transport requires chemical energy, usually in the form of adenosine triphosphate hydrolysis, and can be direction specific, allowing biomolecules to be transported long distances; this is particularly important in neurons due to their complex geometry. In this review a wide range of analytical methods and models of intracellular transport is presented. In the case of diffusive transport, narrow escape problems, diffusion to a small target, confined and single-file diffusion, homogenization theory, and fractional diffusion are considered. In the case of active transport, Brownian ratchets, random walk models, exclusion processes, random intermittent search processes, quasi-steady-state reduction methods, and mean-field approximations are considered. Applications include receptor trafficking, axonal transport, membrane diffusion, nuclear transport, protein-DNA interactions, virus trafficking, and the self-organization of subcellular structures. © 2013 American Physical Society.

  5. Goods Transport Modelling, Vol 1

    DEFF Research Database (Denmark)

    Petersen, Morten Steen (red.); Kristiansen, Jørgen

    The report is a study of data requirements and methodologies for goods transport. The study is intended to provide the basis for general discussion about the application of goods transport models in Denmark. The report provides an overview of different types of models and data availability....

  6. Modelling Ballast Water Transport

    Digital Repository Service at National Institute of Oceanography (India)

    Jayakumar, S.; Babu, M.T.; Vethamony, P.

    Ballast water discharges in the coastal environs have caused a great concern over the recent periods as they account for transporting marine organisms from one part of the world to the other. The movement of discharged ballast water as well...

  7. Hydrogeochemical assessment of groundwater in Kashmir Valley ...

    Indian Academy of Sciences (India)

    Hydrogeochemical assessment of groundwater in Kashmir Valley, India. 1033. Figure 1. Geology of the study area and the location of sampling sites. 4. Results and discussion ..... 1036. G H Jeelani et al. F ig u re. 2 . Spa tia l v a ria tio n o f m a jo r io ns in g ro undw a ter a cro ss the a llu via l ba sin o f the. Ka sh mir. V a lley.

  8. Linking a Large-Watershed Hydrogeochemical Model to a Wetland Community-Ecosystem Model to Estimate Plant Invasion Risk in the Coastal Great Lakes Region, USA

    Science.gov (United States)

    Currie, W. S.; Bourgeau-Chavez, L. L.; Elgersma, K. J.; French, N. H. F.; Goldberg, D. E.; Hart, S.; Hyndman, D. W.; Kendall, A. D.; Martin, S. L.; Martina, J. P.

    2014-12-01

    In the Laurentian Great Lakes region of the Upper Midwest, USA, agricultural and urban land uses together with high N deposition are contributing to elevated flows of N in rivers and groundwater to coastal wetlands. The functioning of coastal wetlands, which provide a vital link between land and water, are imperative to maintaining the health of the entire Great Lakes Basin. Elevated N inflows are believed to facilitate the spread of large-stature invasive plants (cattails and Phragmites) that reduce biodiversity and have complex effects on other ecosystem services including wetland N retention and C accretion. We enhanced the ILHM (Integrated Landscape Hydrology Model) to simulate the effects of land use on N flows in streams, rivers, and groundwater throughout the Lower Peninsula of Michigan. We used the hydroperiods and N loading rates simulated by ILHM as inputs to the Mondrian model of wetland community-ecosystem processes to estimate invasion risk and other ecosystem services in coastal wetlands around the Michigan coast. Our linked models produced threshold behavior in the success of invasive plants in response to N loading, with the threshold ranging from ca. 8 to 12 g N/m2 y, depending on hydroperiod. Plant invasions increased wetland productivity 3-fold over historically oligotrophic native communities, decreased biodiversity but slightly increased wetland N retention. Regardless of invasion, elevated N loading resulted in significantly enhanced rates of C accretion, providing an important region-wide mechanism of C storage. The linked models predicted a general pattern of greater invasion risk in the southern basins of lakes Michigan and Huron relative to northern areas. The basic mechanisms of invasion have been partially validated in our field mesocosms constructed for this project. The general regional patterns of increased invasion risk have been validated through our field campaigns and remote sensing conducted for this project.

  9. Atmospheric Transport Modeling Resources

    Energy Technology Data Exchange (ETDEWEB)

    Mazzola, Carl A. [Stone and Webster Engineering Corporation, Aiken, SC (United States); Addis, Robert P. [Westinghouse Savannah River Company, Aiken, SC (United States)

    1995-03-01

    The purpose of this publication is to provide DOE and other federal agency emergency managers with an in-depth compilation and description of atmospheric dispersion models available to DOE and other Federal sites.

  10. Next Generation Transport Phenomenology Model

    Science.gov (United States)

    Strickland, Douglas J.; Knight, Harold; Evans, J. Scott

    2004-01-01

    This report describes the progress made in Quarter 3 of Contract Year 3 on the development of Aeronomy Phenomenology Modeling Tool (APMT), an open-source, component-based, client-server architecture for distributed modeling, analysis, and simulation activities focused on electron and photon transport for general atmospheres. In the past quarter, column emission rate computations were implemented in Java, preexisting Fortran programs for computing synthetic spectra were embedded into APMT through Java wrappers, and work began on a web-based user interface for setting input parameters and running the photoelectron and auroral electron transport models.

  11. Preliminary Hydrogeochemical Site Description SFR (version 0.2)

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, Ann-Chatrin (Geosigma AB, Uppaala (Sweden)); Tullborg, Eva-Lena (Terralogica AB, Graabo (Sweden)); Smellie, John (Conterra AB, Partille (Sweden))

    2010-05-15

    The final repository for low and intermediate level radioactive operational waste, SFR, located about 150 km north of Stockholm, is to undergo a future extension. The present on-going project, scheduled from 2007 to 2011, is to define and characterise a suitable bedrock volume for the extended repository. This will include the drilling and geoscientific evaluation of seven core-drilled and four percussion boreholes as well as subsequent interpretation and modelling based on the obtained results in order to provide the necessary information for safety assessment and repository design. This report presents a preliminary hydrogeochemical site description for the SFR site and should be considered as an early progress report rather than a complete hydrochemical site descriptive model. The completed hydrogeochemical field investigations have yielded chemical data from a total of 12 borehole sections in five boreholes and additional data from the entire length of two open boreholes in connection with hydraulic tests. These data, together with data from a total of 18 early boreholes in the present SFR tunnel system, were used in the interpretation work. The main part of the data consisted of basic groundwater analyses including major ions and isotopes. Some sporadic gas, microbe and measured redox data are available, but these are either not treated in this report, or are only briefly discussed. This was due to time constraints since special care is needed when interpreting few data of varying quality. The groundwaters in the SFR dataset cover a maximum depth down to about .400 masl and represent a relatively limited salinity range (1,500 to 5,500 mg/L chloride). However, the delta18O values show a wide variation (-1.55 to -0.75% V-SMOW) similar to that reported from the Forsmark site investigations. At the SFR, marine indicators such as Mg/Cl, K/Cl and Br/Cl also show relatively large variations considering the limited salinity range. From very few measured Eh values, and

  12. Size- and concentration-dependent deposition of fluorescent silica colloids in saturated sand columns: transport experiments and modeling.

    Science.gov (United States)

    Vitorge, Elsa; Szenknect, Stéphanie; Martins, Jean M F; Gaudet, Jean-Paul

    2013-08-01

    This study investigates the size and concentration effects on the transport of silica colloids in columns of sandy aquifer material. Colloid transport experiments were performed with specifically developed fluorescent labeled silica colloids in columns of a repacked natural porous medium under hydro-geochemical conditions representative of sandy aquifers. Breakthrough curves and vertical deposition profiles of colloids were measured for various colloid concentrations and sizes. The results showed that for a given colloid concentration injected, deposition increased when increasing the size of the colloids. For a given colloid size, retention was also shown to be highly concentration-dependent with a non-monotonous pattern presenting low and high concentration specificities. Deposition increases when increasing both size and injected concentration, until a threshold concentration is reached, above which retention decreases, thus increasing colloid mobility. Results observed above the threshold concentration agree with a classical blocking mechanism typical of a high concentration regime. Results observed at lower colloid concentrations were not modeled with a classical blocking model and a depth- and time-dependent model with a second order kinetic law was necessary to correctly fit the experimental data in the entire range of colloid concentrations with a single set of parameters for each colloidal size. The colloid deposition mechanisms occuring at low concentrations were investigated through a pore structure analysis carried out with Mercury Intrusion Porosimetry and image analysis. The determined pore size distribution permitted estimation of the maximal retention capacity of the natural sand as well as some low flow zones. Altogether, these results stress the key role of the pore space geometry of the sand in controlling silica colloids deposition under hydro-geochemical conditions typical of sandy aquifers. Our results also showed originally that colloid

  13. Modeling Radionuclide Transport in Clays

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Liange [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Li, Lianchong [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Rutqvist, Jonny [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Liu, Hui -Hai [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Birkholzer, Jens [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-05-01

    tests (e.g. Garcia-Gutierrez et al. 2006, Soler et al. 2008, van Loon et al. 2004, Wu et al. 2009) and numerical modeling (de Windt et al. 2003; 2006), the effects of THMC processes on radionuclide transport are not fully investigated. The objectives of the research activity documented in this report are to improve a modeling capability for coupled THMC processes and to use it to evaluate the THMC impacts on radionuclide transport. This research activity addresses several key Features, Events and Processes (FEPs), including FEP 2.2.08, Hydrologic Processes, FEP 2.2.07, Mechanical Processes and FEP 2.2.09, Chemical Process— Transport, by studying near-field coupled THMC processes in clay/shale repositories and their impacts on radionuclide transport. This report documents the progress that has been made in FY12. Section 2 discusses the development of THMC modeling capability. Section 3 reports modeling results of THMC impacts on radionuclide transport. Planned work for the remaining months of FY12 and proposed work for FY13 are presented in Section 4.

  14. Hydrogeochemical evaluation. Preliminary site description Laxemar subarea - version 1.2

    Energy Technology Data Exchange (ETDEWEB)

    Laaksoharju, Marcus (ed.) [Geopoint AB, Stockholm (Sweden)

    2006-04-15

    hydrochemical groups of groundwaters have been identified. Characterisation of pore water in core samples from the Laxemar borehole, KLX03, shows that chemical and isotopic pore water signatures have a characteristic variation of groundwater composition with rock type and depth that is in close agreement with the general trends in hydrochemistry of the adjacent formation (fracture) groundwaters. There is little apparent evidence of a glacial melt signature in the pore waters. Pore waters at depth show an affinity with deep brine evolution. Steady state conditions between pore water and formation groundwaters in the fractures are essentially only developed in the shallow zone of the Aevroe granite, while at depths greater than 450 m the chemical and isotopic composition of the pore water differs markedly from that of the fracture groundwaters in fractures. Diffusion between rock pore water and adjacent fracture groundwaters is identified as the dominant transport process; calculated diffusion coefficients agree well with current knowledge of conditions in the Laxemar site. In this report the models and the site understanding have been consolidated. Despite relatively few new data from depth, the models have been updated and the further understanding gained of groundwater origin, groundwater evolution, reactions, studies of interaction between shallow and deep groundwater, pore water composition in bedrock, microbial depth variation, uncertainties of the mixing calculations, tritium variations with time and 3D visualisation of the spatial variability of groundwater properties. An updated Hydrogeochemical Site Descriptive Model version 1.2 for Laxemar subarea has evolved. The resulting description has improved compared with the 1.2 version for Simpevarp subarea by producing a more detailed process modelling, uncertainty analysis and 3D visualisation. The microbial characterisation gives direct support to, for example, the redox modelling. The coupled transport modelling can

  15. Modelling of radon transport in porous media

    NARCIS (Netherlands)

    van der Graaf, E.R.; de Meijer, R.J.; Katase, A; Shimo, M

    1998-01-01

    This paper aims to describe the state of the art of modelling radon transport in soil on basis of multiphase radon transport equations. Emphasis is given to methods to obtain a consistent set of input parameters needed For such models. Model-measurement comparisons with the KVI radon transport

  16. Transport Properties for Combustion Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Brown, N.J.; Bastein, L.; Price, P.N.

    2010-02-19

    This review examines current approximations and approaches that underlie the evaluation of transport properties for combustion modeling applications. Discussed in the review are: the intermolecular potential and its descriptive molecular parameters; various approaches to evaluating collision integrals; supporting data required for the evaluation of transport properties; commonly used computer programs for predicting transport properties; the quality of experimental measurements and their importance for validating or rejecting approximations to property estimation; the interpretation of corresponding states; combination rules that yield pair molecular potential parameters for unlike species from like species parameters; and mixture approximations. The insensitivity of transport properties to intermolecular forces is noted, especially the non-uniqueness of the supporting potential parameters. Viscosity experiments of pure substances and binary mixtures measured post 1970 are used to evaluate a number of approximations; the intermediate temperature range 1 < T* < 10, where T* is kT/{var_epsilon}, is emphasized since this is where rich data sets are available. When suitable potential parameters are used, errors in transport property predictions for pure substances and binary mixtures are less than 5 %, when they are calculated using the approaches of Kee et al.; Mason, Kestin, and Uribe; Paul and Warnatz; or Ern and Giovangigli. Recommendations stemming from the review include (1) revisiting the supporting data required by the various computational approaches, and updating the data sets with accurate potential parameters, dipole moments, and polarizabilities; (2) characterizing the range of parameter space over which the fit to experimental data is good, rather than the current practice of reporting only the parameter set that best fits the data; (3) looking for improved combining rules, since existing rules were found to under-predict the viscosity in most cases; (4

  17. Directions in Radiation Transport Modelling

    Directory of Open Access Journals (Sweden)

    P Nicholas Smith

    2016-12-01

    More exciting advances are on the horizon to increase the power of simulation tools. The advent of high performance computers is allowing bigger, higher fidelity models to be created, if the challenges of parallelization and memory management can be met. 3D whole core transport modelling is becoming possible. Uncertainty quantification is improving with large benefits to be gained from more accurate, less pessimistic estimates of uncertainty. Advanced graphical displays allow the user to assimilate and make sense of the vast amounts of data produced by modern modelling tools. Numerical solvers are being developed that use goal-based adaptivity to adjust the nodalisation of the system to provide the optimum scheme to achieve the user requested accuracy on the results, thus removing the need to perform costly convergence studies in space and angle etc. More use is being made of multi-physics methods in which radiation transport is coupled with other phenomena, such as thermal-hydraulics, structural response, fuel performance and/or chemistry in order to better understand their interplay in reactor cores.

  18. Up-gradient transport in a probabilistic transport model

    DEFF Research Database (Denmark)

    Gavnholt, J.; Juul Rasmussen, J.; Garcia, O.E.

    2005-01-01

    The transport of particles or heat against the driving gradient is studied by employing a probabilistic transport model with a characteristic particle step length that depends on the local concentration or heat gradient. When this gradient is larger than a prescribed critical value, the standard....... These results supplement recent works by van Milligen [Phys. Plasmas 11, 3787 (2004)], which applied Levy distributed step sizes in the case of supercritical gradients to obtain the up-gradient transport. (c) 2005 American Institute of Physics....

  19. Hydrogeological and Hydrogeochemical Modelling of the Alicun de las Torres Termal System (Province of Granada). Isotope Hydrochemistry and Gases in Groundwaters; Modelizacion Hidrogeologica e Hidrogeoquimica del Sistema Termal de Alicun de Las Torres (Provincia de Granada). Hidroquimica Isotopica y Gases en Aguas

    Energy Technology Data Exchange (ETDEWEB)

    Prado Perez, A. J.; Delgado, A.; Crespo, M. T.; Martin, A.; Vaselli, O.; Perez del Villar, L.

    2010-11-17

    In the framework of a Singular Strategic Project entitled: {sup A}dvanced Technologies of Carbon, Capture and Storage (CCS){sup ,} supported by the MICINN (Spain) and the FEDER founds (EU), specifically in the Carbon Storage Task, a comprehensive study on the CO{sub 2} leakage as DIC (Dissolved Inorganic Carbon) in the Alicun de Las Torres (Prov. of Granada) natural analogue thermal system was envisaged. This analogous system is characterised by the presence of a very important travertine formation, which can be considered as a permanent and stable sink for CO{sub 2}. In order to explain the formation of these travertine mass an hydrogeological and hydrogeochemical model of the area has been established by using the hydrochemical data, the stable and radioactive isotope characteristics, the dissolved inorganic carbon, as well as the chemical and isotopic composition of the free and dissolved gases of the above mentioned Thermal System. (Author) 11 refs.

  20. Modeling energy transport in nanostructures

    Science.gov (United States)

    Pattamatta, Arvind

    Heat transfer in nanostructures differ significantly from that in the bulk materials since the characteristic length scales associated with heat carriers, i.e., the mean free path and the wavelength, are comparable to the characteristic length of the nanostructures. Nanostructure materials hold the promise of novel phenomena, properties, and functions in the areas of thermal management and energy conversion. Example of thermal management in micro/nano electronic devices is the use of efficient nanostructured materials to alleviate 'hot spots' in integrated circuits. Examples in the manipulation of heat flow and energy conversion include nanostructures for thermoelectric energy conversion, thermophotovoltaic power generation, and data storage. One of the major challenges in Metal-Oxide Field Effect Transistor (MOSFET) devices is to study the 'hot spot' generation by accurately modeling the carrier-optical phonon-acoustic phonon interactions. Prediction of hotspot temperature and position in MOSFET devices is necessary for improving thermal design and reliability of micro/nano electronic devices. Thermoelectric properties are among the properties that may drastically change at nanoscale. The efficiency of thermoelectric energy conversion in a material is measured by a non-dimensional figure of merit (ZT) defined as, ZT = sigmaS2T/k where sigma is the electrical conductivity, S is the Seebeck coefficient, T is the temperature, and k is the thermal conductivity. During the last decade, advances have been made in increasing ZT using nanostructures. Three important topics are studied with respect to energy transport in nanostructure materials for micro/nano electronic and thermoelectric applications; (1) the role of nanocomposites in improving the thermal efficiency of thermoelectric devices, (2) the interfacial thermal resistance for the semiconductor/metal contacts in thermoelectric devices and for metallic interconnects in micro/nano electronic devices, (3) the

  1. Use of Models in Urban Transportation Planning

    Science.gov (United States)

    1973-04-01

    The report describes the most commonly used models in urban transportation planning. A background on urban transportation planning is given including changes in planning objectives and the effects of Federal legislation. General concepts and problems...

  2. Hydrogeochemical characteristics of the River Idrijca (Slovenia

    Directory of Open Access Journals (Sweden)

    Tjaša Kanduč

    2008-06-01

    Full Text Available The hydrogeochemical and isotope characteristics of the River Idrijca, Slovenia, where the world’s second largest mercury (Hg mine is located, were investigated. The River Idrijca, a typical steep mountain river has an HCO3- - Ca2+ - Mg2+ chemical composition. Its Ca2+/Mg2+ molar ratio indicates that dolomite weathering prevails in the watershed. The River Idrijca and its tributaries are over saturated with respect to calcite and dolomite. The pCO2 pressure is up to 13 times over atmospheric pressure and represents a source of CO2 to the atmosphere. δ18O values in river water indicate primary control from precipitation and enrichment of the heavy oxygen isotope of infiltrating water recharging the River Idrijca from its slopes.The δ13 CDIC values range from −10.8 to −6.6 ‰ and are controlled by biogeochemical processes in terrestrial environments and in the stream: 1 exchange with atmospheric CO2, 2 degradation of organic matter, 3 dissolution of carbonates, and 4 tributaries. The contributions of these inputs were calculated according to steady state equations and are estimated to be -11 %: 19 %: 31 %: 61 % in the autumn and 0 %: 6 %: 9 %: 35 % in the spring sampling seasons.

  3. Modelling of Transport Projects Uncertainties

    DEFF Research Database (Denmark)

    Salling, Kim Bang; Leleur, Steen

    2009-01-01

    This paper proposes a new way of handling the uncertainties present in transport decision making based on infrastructure appraisals. The paper suggests to combine the principle of Optimism Bias, which depicts the historical tendency of overestimating transport related benefits and underestimating......-based graphs which function as risk-related decision support for the appraised transport infrastructure project....

  4. SATURATED ZONE FLOW AND TRANSPORT MODEL ABSTRACTION

    Energy Technology Data Exchange (ETDEWEB)

    B.W. ARNOLD

    2004-10-27

    The purpose of the saturated zone (SZ) flow and transport model abstraction task is to provide radionuclide-transport simulation results for use in the total system performance assessment (TSPA) for license application (LA) calculations. This task includes assessment of uncertainty in parameters that pertain to both groundwater flow and radionuclide transport in the models used for this purpose. This model report documents the following: (1) The SZ transport abstraction model, which consists of a set of radionuclide breakthrough curves at the accessible environment for use in the TSPA-LA simulations of radionuclide releases into the biosphere. These radionuclide breakthrough curves contain information on radionuclide-transport times through the SZ. (2) The SZ one-dimensional (I-D) transport model, which is incorporated in the TSPA-LA model to simulate the transport, decay, and ingrowth of radionuclide decay chains in the SZ. (3) The analysis of uncertainty in groundwater-flow and radionuclide-transport input parameters for the SZ transport abstraction model and the SZ 1-D transport model. (4) The analysis of the background concentration of alpha-emitting species in the groundwater of the SZ.

  5. Logistics and Transport - a conceptual model

    DEFF Research Database (Denmark)

    Jespersen, Per Homann; Drewes, Lise

    2004-01-01

    This paper describes how the freight transport sector is influenced by logistical principles of production and distribution. It introduces new ways of understanding freight transport as an integrated part of the changing trends of mobility. By introducing a conceptual model for understanding...... the interaction between logistics and transport, it points at ways to over-come inherent methodological difficulties when studying this relation...

  6. RADIONUCLIDE TRANSPORT MODELS UNDER AMBIENT CONDITIONS

    Energy Technology Data Exchange (ETDEWEB)

    S. Magnuson

    2004-11-01

    The purpose of this model report is to document the unsaturated zone (UZ) radionuclide transport model, which evaluates, by means of three-dimensional numerical models, the transport of radioactive solutes and colloids in the UZ, under ambient conditions, from the repository horizon to the water table at Yucca Mountain, Nevada.

  7. Modelling of Transport Projects Uncertainties

    DEFF Research Database (Denmark)

    Salling, Kim Bang; Leleur, Steen

    2012-01-01

    This paper proposes a new way of handling the uncertainties present in transport decision making based on infrastructure appraisals. The paper suggests to combine the principle of Optimism Bias, which depicts the historical tendency of overestimating transport related benefits and underestimating......-based graphs which functions as risk-related decision support for the appraised transport infrastructure project. The presentation of RSF is demonstrated by using an appraisal case concerning a new airfield in the capital of Greenland, Nuuk....

  8. Biological transportation networks: Modeling and simulation

    KAUST Repository

    Albi, Giacomo

    2015-09-15

    We present a model for biological network formation originally introduced by Cai and Hu [Adaptation and optimization of biological transport networks, Phys. Rev. Lett. 111 (2013) 138701]. The modeling of fluid transportation (e.g., leaf venation and angiogenesis) and ion transportation networks (e.g., neural networks) is explained in detail and basic analytical features like the gradient flow structure of the fluid transportation network model and the impact of the model parameters on the geometry and topology of network formation are analyzed. We also present a numerical finite-element based discretization scheme and discuss sample cases of network formation simulations.

  9. Modeling activity transport in the CANDU heat transport system

    Energy Technology Data Exchange (ETDEWEB)

    Guzonas, D.A.; Qiu, L. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    2010-07-01

    The release and transport of corrosion products from the surfaces of primary coolant system components is a serious concern for all water-cooled nuclear power plants. The consequences of high levels of corrosion product transport are twofold: a) increased corrosion product (crud) deposition on fuel cladding surfaces, leading to reduced heat transfer and the possibility of fuel failures, and b) increased production of radioactive species by neutron activation, resulting in increased out-of-core radiation fields and worker dose. In recent years, a semi-empirical activity transport model has been successfully developed to predict the deposition of radionuclides, including {sup 60}Co, {sup 95}Zr, {sup 124}Sb and fission products, around the CANDU® primary Heat Transport System (HTS), and to predict radiation fields at the steam generators and reactor face. The model links corrosion of the carbon steel outlet feeders to magnetite and radionuclide deposition on steam generator and inlet piping surfaces. This paper will describe the model development, key assumptions, required inputs, and model validation. The importance of reactor artefact characterization in the model development will be highlighted, and some key results will be presented, including oxide morphology and loadings, and radionuclide distributions within the oxide. The predictive capabilities of the model will also be described, including predictions of oxide thickness and the effects of changes in chemistry parameters such as alkalinity. While the model was developed primarily for the CANDU® HTS, the information gained during model development regarding corrosion product and radionuclide transport and deposition can also provide insights into activity transport in other water-cooled reactor systems. (author)

  10. Modeling phosphate transport and removal in a compact bed filled with a mineral-based sorbent for domestic wastewater treatment.

    Science.gov (United States)

    Herrmann, Inga; Jourak, Amir; Gustafsson, Jon Petter; Hedström, Annelie; Lundström, T Staffan; Viklander, Maria

    2013-11-01

    Phosphorus filter units containing mineral-based sorbents with a high phosphate (PO4) binding capacity have been shown to be appropriate for removing PO4 in the treatment of domestic wastewater in on-site facilities. However, a better understanding of their PO4 removal mechanisms, and reactions that could lead to the formation of PO4 compounds, is required to evaluate the potential utility of candidate sorbents. Models based on data obtained from laboratory-scale experiments with columns of selected materials can be valuable for acquiring such understanding. Thus, in this study the transport and removal of PO4 in experiments with a laboratory-scale column filled with a commercial silicate-based sorbent were modeled, using the hydro-geochemical transport code PHREEQC. The resulting models, that incorporated the dissolution of calcite, kinetic constrains for the dissolution of calcium oxide (CaO) and wollastonite (CaSiO3), and the precipitation of amorphous tricalcium phosphate, Ca3(PO4)2, successfully simulated the removal of PO4 observed in the experiments. © 2013. Published by Elsevier B.V. All rights reserved.

  11. A Mercury Model of Atmospheric Transport

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, Alex B. [Oregon State Univ., Corvallis, OR (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chodash, Perry A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Procassini, R. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2018-01-19

    Using the particle transport code Mercury, accurate models were built of the two sources used in Operation BREN, a series of radiation experiments performed by the United States during the 1960s. In the future, these models will be used to validate Mercury’s ability to simulate atmospheric transport.

  12. The european Trans-Tools transport model

    NARCIS (Netherlands)

    Rooijen, T. van; Burgess, A.

    2008-01-01

    The paper presents the use of ArcGIS in the Transtools Transport Model, TRANS-TOOLS, created by an international consortium for the European Commission. The model describe passenger as well as freight transport in Europe with all medium and long distance modes (cars, vans, trucks, train, inland

  13. Optimal transportation networks models and theory

    CERN Document Server

    Bernot, Marc; Morel, Jean-Michel

    2009-01-01

    The transportation problem can be formalized as the problem of finding the optimal way to transport a given measure into another with the same mass. In contrast to the Monge-Kantorovitch problem, recent approaches model the branched structure of such supply networks as minima of an energy functional whose essential feature is to favour wide roads. Such a branched structure is observable in ground transportation networks, in draining and irrigation systems, in electrical power supply systems and in natural counterparts such as blood vessels or the branches of trees. These lectures provide mathematical proof of several existence, structure and regularity properties empirically observed in transportation networks. The link with previous discrete physical models of irrigation and erosion models in geomorphology and with discrete telecommunication and transportation models is discussed. It will be mathematically proven that the majority fit in the simple model sketched in this volume.

  14. Uncertainty in tsunami sediment transport modeling

    Science.gov (United States)

    Jaffe, Bruce E.; Goto, Kazuhisa; Sugawara, Daisuke; Gelfenbaum, Guy R.; La Selle, SeanPaul M.

    2016-01-01

    Erosion and deposition from tsunamis record information about tsunami hydrodynamics and size that can be interpreted to improve tsunami hazard assessment. We explore sources and methods for quantifying uncertainty in tsunami sediment transport modeling. Uncertainty varies with tsunami, study site, available input data, sediment grain size, and model. Although uncertainty has the potential to be large, published case studies indicate that both forward and inverse tsunami sediment transport models perform well enough to be useful for deciphering tsunami characteristics, including size, from deposits. New techniques for quantifying uncertainty, such as Ensemble Kalman Filtering inversion, and more rigorous reporting of uncertainties will advance the science of tsunami sediment transport modeling. Uncertainty may be decreased with additional laboratory studies that increase our understanding of the semi-empirical parameters and physics of tsunami sediment transport, standardized benchmark tests to assess model performance, and development of hybrid modeling approaches to exploit the strengths of forward and inverse models.

  15. Evaluation of conceptual, mathematical and physical-and-chemical models for describing subsurface radionuclide transport at the Lake Karachai Waste Disposal Site

    Energy Technology Data Exchange (ETDEWEB)

    Rumynin, V.G.; Mironenko, V.A.; Sindalovsky, L.N.; Boronina, A.V.; Konosavsky, P.K.; Pozdniakov, S.P.

    1998-06-01

    The goal of this work was to develop the methodology and to improve understanding of subsurface radionuclide transport for application to the Lake Karachai Site and to identify the influence of the processes and interactions involved into transport and fate of the radionuclides. The report is focused on two sets of problems, which have to do both with, hydrodynamic and hydrogeochemical aspects of the contaminant transport.

  16. Concept Layout Model of Transportation Terminals

    Directory of Open Access Journals (Sweden)

    Li-ya Yao

    2012-01-01

    Full Text Available Transportation terminal is the key node in transport systems. Efficient terminals can improve operation of passenger transportation networks, adjust the layout of public transportation networks, provide a passenger guidance system, and regulate the development of commercial forms, as well as optimize the assembly and distribution of modern logistic modes, among others. This study aims to clarify the relationship between the function and the structure of transportation terminals and establish the function layout design. The mapping mechanism of demand, function, and structure was analyzed, and a quantitative relationship between function and structure was obtained from a design perspective. Passenger demand and terminal structure were decomposed into several demand units and structural elements following the principle of reverse engineering. The relationship maps between these two kinds of elements were then analyzed. Function-oriented concept layout model of transportation terminals was established using the previous method. Thus, a technique in planning and design of transportation structures was proposed. Meaningful results were obtained from the optimization of transportation terminal facilities, which guide the design of the functional layout of transportation terminals and improve the development of urban passenger transportation systems.

  17. Uncertainty calculation in transport models and forecasts

    DEFF Research Database (Denmark)

    Manzo, Stefano; Prato, Carlo Giacomo

    Transport projects and policy evaluations are often based on transport model output, i.e. traffic flows and derived effects. However, literature has shown that there is often a considerable difference between forecasted and observed traffic flows. This difference causes misallocation of (public......, infrastructure, and regulation) and demand. Uncertainty pertains to everything the modeller does not know to a full extent about the system object of the modelling process due to a limited knowledge or stochasticity of some model components. Thus, ultimately uncertainty reflects the inability of the modeller...... the uncertainty propagation pattern over time specific for key model outputs becomes strategically important. 1 Manzo, S., Nielsen, O. A. & Prato, C. G. (2014). The Effects of uncertainty in speed-flow curve parameters on a large-scale model. Transportation Research Record, 1, 30-37. 2 Manzo, S., Nielsen, O. A...

  18. Multimodal transportation best practices and model element.

    Science.gov (United States)

    2014-06-01

    This report provides guidance in developing a multimodal transportation element of a local government comprehensive : plan. Two model elements were developed to address differences in statutory requirements for communities of different : sizes and pl...

  19. NODA for EPA's Updated Ozone Transport Modeling

    Science.gov (United States)

    Find EPA's NODA for the Updated Ozone Transport Modeling Data for the 2008 Ozone National Ambient Air Quality Standard (NAAQS) along with the ExitExtension of Public Comment Period on CSAPR for the 2008 NAAQS.

  20. Boltzmann Transport in Hybrid PIC HET Modeling

    Science.gov (United States)

    2015-07-01

    Paper 3. DATES COVERED (From - To) July 2015-July 2015 4. TITLE AND SUBTITLE Boltzmann transport in hybrid PIC HET modeling 5a. CONTRACT NUMBER In...reproduce experimentally observed mobility trends derived from HPHall, a workhorse hybrid- PIC HET simulation code. 15. SUBJECT TERMS 16. SECURITY...Std. 239.18 Boltzmann transport in hybrid PIC HET modeling IEPC-2015- /ISTS-2015-b- Presented at Joint Conference of 30th International

  1. Computational modeling of ion transport through nanopores

    Science.gov (United States)

    Modi, Niraj; Winterhalter, Mathias; Kleinekathöfer, Ulrich

    2012-09-01

    Nanoscale pores are ubiquitous in biological systems while artificial nanopores are being fabricated for an increasing number of applications. Biological pores are responsible for the transport of various ions and substrates between the different compartments of biological systems separated by membranes while artificial pores are aimed at emulating such transport properties. As an experimental method, electrophysiology has proven to be an important nano-analytical tool for the study of substrate transport through nanopores utilizing ion current measurements as a probe for the detection. Independent of the pore type, i.e., biological or synthetic, and objective of the study, i.e., to model cellular processes of ion transport or electrophysiological experiments, it has become increasingly important to understand the dynamics of ions in nanoscale confinements. To this end, numerical simulations have established themselves as an indispensable tool to decipher ion transport processes through biological as well as artificial nanopores. This article provides an overview of different theoretical and computational methods to study ion transport in general and to calculate ion conductance in particular. Potential new improvements in the existing methods and their applications are highlighted wherever applicable. Moreover, representative examples are given describing the ion transport through biological and synthetic nanopores as well as the high selectivity of ion channels. Special emphasis is placed on the usage of molecular dynamics simulations which already have demonstrated their potential to unravel ion transport properties at an atomic level.

  2. Real time model for public transportation management

    Directory of Open Access Journals (Sweden)

    Ireneusz Celiński

    2014-03-01

    Full Text Available Background: The article outlines managing a public transportation fleet in the dynamic aspect. There are currently many technical possibilities of identifying demand in the transportation network. It is also possible to indicate legitimate basis of estimating and steering demand. The article describes a general public transportation fleet management concept based on balancing demand and supply. Material and methods: The presented method utilizes a matrix description of demand for transportation based on telemetric and telecommunication data. Emphasis was placed mainly on a general concept and not the manner in which data was collected by other researchers.  Results: The above model gave results in the form of a system for managing a fleet in real-time. The objective of the system is also to optimally utilize means of transportation at the disposal of service providers. Conclusions: The presented concept enables a new perspective on managing public transportation fleets. In case of implementation, the project would facilitate, among others, designing dynamic timetables, updated based on observed demand, and even designing dynamic points of access to public transportation lines. Further research should encompass so-called rerouting based on dynamic measurements of the characteristics of the transportation system.

  3. Radionuclide Transport Models Under Ambient Conditions

    Energy Technology Data Exchange (ETDEWEB)

    G. Moridis; Q. Hu

    2001-12-20

    The purpose of Revision 00 of this Analysis/Model Report (AMR) is to evaluate (by means of 2-D semianalytical and 3-D numerical models) the transport of radioactive solutes and colloids in the unsaturated zone (UZ) under ambient conditions from the potential repository horizon to the water table at Yucca Mountain (YM), Nevada.

  4. System Convergence in Transport Modelling

    DEFF Research Database (Denmark)

    Rich, Jeppe; Nielsen, Otto Anker; Cantarella, Guilio E.

    2010-01-01

    -of-successive-averages (MSA) have been proposed. Convergence of the MSA under fairly weak regularity conditions was shown in Robbins and Monro (1951). The iteration between demand and assignment ? the external equilibrium ? are in many models either decoupled or follow a very simple iteration pattern. However, as demand...

  5. Commercial Consolidation Model Applied to Transport Infrastructure

    Energy Technology Data Exchange (ETDEWEB)

    Guilherme de Aragão, J.J.; Santos Fontes Pereira, L. dos; Yamashita, Y.

    2016-07-01

    Since the 1990s, transport concessions, including public-private partnerships (PPPs), have been increasingly adopted by governments as an alternative for financing and operations in public investments, especially in transport infrastructure. The advantage pointed out by proponents of these models lies in merging the expertise and capital of the private sector to the public interest. Several arrangements are possible and have been employed in different cases. After the duration of the first PPP contracts in transportation, many authors have analyzed the success and failure factors of partnerships. The occurrence of failures in some stages of the process can greatly encumber the public administration, incurring losses to the fiscal responsibility of the competent bodies. This article aims to propose a new commercial consolidation model applied to transport infrastructure to ensure fiscal sustainability and overcome the weaknesses of current models. Initially, a systematic review of the literature covering studies on transport concessions between 1990 and 2015 is offered, where the different approaches between various countries are compared and the critical success factors indicated in the studies are identified. In the subsequent part of the paper, an approach for the commercial consolidation of the infrastructure concessions is presented, where the concessionary is paid following a finalistic performance model, which includes the overall fiscal balance of regional growth. Finally, the papers analyses the usefulness of the model in coping with the critical success factors explained before. (Author)

  6. A Sediment Transport Model for Sewers

    DEFF Research Database (Denmark)

    Mark, Ole; Larsson, Johan; Larsen, Torben

    1993-01-01

    This paper describes a mathematical model for transport processes in sewers. The model consists of three sub models, a surface model for the description of the buildup and the washoff of sediment particles from the surface area, a morphological model and an advection-dispersion model. The model...... is being developed as a part of a study being carried out at the University of Aalborg, Denmark and VBB VIAK, Sweden. The project is funded by the Swedish Water and Waste Water Works Association and the Nordic Industrial Foundation....

  7. Radionuclide Transport Models Under Ambient Conditions

    Energy Technology Data Exchange (ETDEWEB)

    G. Moridis; Q. Hu

    2000-03-12

    The purpose of this Analysis/Model Report (AMR) is to evaluate (by means of 2-D semianalytical and 3-D numerical models) the transport of radioactive solutes and colloids in the unsaturated zone (UZ) under ambient conditions from the potential repository horizon to the water table at Yucca Mountain (YM), Nevada. This is in accordance with the ''AMR Development Plan U0060, Radionuclide Transport Models Under Ambient Conditions'' (CRWMS M and O 1999a). This AMR supports the UZ Flow and Transport Process Model Report (PMR). This AMR documents the UZ Radionuclide Transport Model (RTM). This model considers: the transport of radionuclides through fractured tuffs; the effects of changes in the intensity and configuration of fracturing from hydrogeologic unit to unit; colloid transport; physical and retardation processes and the effects of perched water. In this AMR they document the capabilities of the UZ RTM, which can describe flow (saturated and/or unsaturated) and transport, and accounts for (a) advection, (b) molecular diffusion, (c) hydrodynamic dispersion (with full 3-D tensorial representation), (d) kinetic or equilibrium physical and/or chemical sorption (linear, Langmuir, Freundlich or combined), (e) first-order linear chemical reaction, (f) radioactive decay and tracking of daughters, (g) colloid filtration (equilibrium, kinetic or combined), and (h) colloid-assisted solute transport. Simulations of transport of radioactive solutes and colloids (incorporating the processes described above) from the repository horizon to the water table are performed to support model development and support studies for Performance Assessment (PA). The input files for these simulations include transport parameters obtained from other AMRs (i.e., CRWMS M and O 1999d, e, f, g, h; 2000a, b, c, d). When not available, the parameter values used are obtained from the literature. The results of the simulations are used to evaluate the transport of radioactive

  8. Hydrogeochemical evaluation. Preliminary site description Forsmark area - version 1.2

    Energy Technology Data Exchange (ETDEWEB)

    Laaksoharju, Marcus (ed.) [Geopoint AB, Stockholm (Sweden)

    2005-03-15

    Siting studies for SKB's programme of deep geological disposal of nuclear fuel waste currently involves the investigation of two locations, Forsmark and Laxemar-Simpevarp, on the eastern coast of Sweden to determine their geological, hydrogeochemical and hydrogeological characteristics. Present work completed has resulted in Model version 1.2 which represents the second evaluation of the available Forsmark groundwater analytical data collected up to June, 2004. The Hydrochemical Analytical Group (HAG) had access to data where a total of 1,131 water samples had been collected from the surface and sub-surface environment; 252 samples were collected from drilled boreholes. The deepest fracture groundwater samples with sufficient analytical data reflected depths down to 1 km. Most of the waters sampled (66%) lacked crucial analytical information that restricted the evaluation. Model version 1.2 focuses on geochemical and mixing processes affecting the groundwater composition in the uppermost part of the bedrock, down to repository levels, and eventually extending to 1,000 m depth. The complex groundwater evolution and patterns at Forsmark are a result of many factors such as: a) the present-day topography and proximity to the Baltic Sea, b) past changes in hydrogeology related to glaciation/deglaciation, land uplift and repeated marine/lake water regressions/ transgressions, and c) organic or inorganic alteration of the groundwater composition caused by microbial processes or water/rock interactions. The sampled groundwaters reflect to various degrees processes relating to modern or ancient water/rock interactions and mixing. The groundwater flow regimes at Forsmark are considered local and extend down to depths of around 600 m depending on hydraulic conditions. Close to the Baltic Sea coastline where topographical variation is even less, groundwater flow penetration to depth will subsequently be less marked and such areas will tend to be characterised by

  9. GEOS-5 Chemistry Transport Model User's Guide

    Science.gov (United States)

    Kouatchou, J.; Molod, A.; Nielsen, J. E.; Auer, B.; Putman, W.; Clune, T.

    2015-01-01

    The Goddard Earth Observing System version 5 (GEOS-5) General Circulation Model (GCM) makes use of the Earth System Modeling Framework (ESMF) to enable model configurations with many functions. One of the options of the GEOS-5 GCM is the GEOS-5 Chemistry Transport Model (GEOS-5 CTM), which is an offline simulation of chemistry and constituent transport driven by a specified meteorology and other model output fields. This document describes the basic components of the GEOS-5 CTM, and is a user's guide on to how to obtain and run simulations on the NCCS Discover platform. In addition, we provide information on how to change the model configuration input files to meet users' needs.

  10. Modelling Transition Towards Sustainable Transportation Sector

    DEFF Research Database (Denmark)

    Dominkovic, Dominik Franjo; Bačeković, I.; Mýrdal, Jón Steinar Garðarsson

    2016-01-01

    In a transition towards 100% renewable energy system, transportation sector is rarely dealt withusing the holistic approach and measuring its impact on the whole energy system. Furthermore, assolutions for power and heat sectors are clearer, it is a tendency of the researchers to focus on thelatter...... two energy sectors. In order to deal with the raised issue, authors of this paper developed amethodology for calculation of the transition towards sustainable transport sector, focusing on thesolutions that are already available. Furthermore, as a part of the model, a detailed mapping ofresources...... needed has been carried out for each of the alternatives. It was shown that theelectrification of the transportation sector is a crucial point in transition, while for the transportmodes that cannot be electrified, or shifted to different transportation modes, four alternatives weredefined: synthetic...

  11. Transportation Telematics Systems Operation Efficiency Modeling

    Science.gov (United States)

    Siergiejczyk, Mirosław

    2012-03-01

    In the paper is presented a method of assessing of the exploitation efficiency of transport telematics systems. In order to obtain as an overall assessment of transport telematics systems, as the method for evaluating was accepted the multi-state analysis of the exploitation process. Then was elaborated the model of exploitation process of the telematics system. The problem of fundamental importance in the study of efficiency is to determine the partial measures of effectiveness. Using the characteristics of the exploitation process, a model of exploitation efficiency of telematics system was elaborated and the measures of its evaluation are presented.

  12. Multi-compartment Aerosol Transport Model

    Energy Technology Data Exchange (ETDEWEB)

    Hubbard, Joshua Allen; Santarpia, Joshua; Brotherton, Christopher M.; Omana, Michael Alexis; Rivera, Danielle; Lucero, Gabriel Anthony

    2017-06-01

    A simple aerosol transport model was developed for a multi-compartmented cleanroom. Each compartment was treated as a well-mixed volume with ventilating supply and return air. Gravitational settling, intercompartment transport, and leakage of exterior air into the system were included in the model. A set of first order, coupled, ordinary differential equations was derived from the conservation equations of aerosol mass and air mass. The system of ODEs was then solved in MATLAB using pre-existing numerical methods. The model was verified against cases of (1) constant inlet-duct concentration, and (2) exponentially decaying inlet-duct concentration. Numerical methods resulted in normalized error of less than 10 -9 when model solutions were compared to analytical solutions. The model was validated against experimental measurements from a single field test and showed good agreement in the shape and magnitude of the aerosol concentration profile with time.

  13. Error estimation and adaptive chemical transport modeling

    Directory of Open Access Journals (Sweden)

    Malte Braack

    2014-09-01

    Full Text Available We present a numerical method to use several chemical transport models of increasing accuracy and complexity in an adaptive way. In largest parts of the domain, a simplified chemical model may be used, whereas in certain regions a more complex model is needed for accuracy reasons. A mathematically derived error estimator measures the modeling error and provides information where to use more accurate models. The error is measured in terms of output functionals. Therefore, one has to consider adjoint problems which carry sensitivity information. This concept is demonstrated by means of ozone formation and pollution emission.

  14. Model for Microcirculation Transportation Network Design

    Directory of Open Access Journals (Sweden)

    Qun Chen

    2012-01-01

    Full Text Available The idea of microcirculation transportation was proposed to shunt heavy traffic on arterial roads through branch roads. The optimization model for designing micro-circulation transportation network was developed to pick out branch roads as traffic-shunting channels and determine their required capacity, trying to minimize the total reconstruction expense and land occupancy subject to saturation and reconstruction space constraints, while accounting for the route choice behaviour of network users. Since micro-circulation transportation network design problem includes both discrete and continuous variables, a discretization method was developed to convert two groups of variables (discrete variables and continuous variables into one group of new discrete variables, transforming the mixed network design problem into a new kind of discrete network design problem with multiple values. The genetic algorithm was proposed to solve the new discrete network design problem. Finally a numerical example demonstrated the efficiency of the model and algorithm.

  15. Climate impact of transportation A model comparison

    NARCIS (Netherlands)

    Girod, B.; Vuuren, D.P. van; Grahn, M.; Kitous, A.; Kim, S.H.; Kyle, P.

    2013-01-01

    Transportation contributes to a significant and rising share of global energy use and GHG emissions. Therefore modeling future travel demand, its fuel use, and resulting CO2 emission is highly relevant for climate change mitigation. In this study we compare the baseline projections for global

  16. Equilibrium models in multimodal container transport systems

    NARCIS (Netherlands)

    Corman, F.; Viti, F.; Negenborn, R.R.

    2015-01-01

    Optimizing the performance of multimodal freight transport networks involves adequately balancing the interplay between costs, volumes, times of departure and arrival, and times of travel. In order to study this interplay, we propose an assignment model that is able to efficiently determine flows

  17. Modelling anisotropic water transport in polymer composite ...

    Indian Academy of Sciences (India)

    This work reports anisotropic water transport in a polymer composite consisting of an epoxy matrix reinforced with aligned triangular bars made of vinyl ester. By gravimetric experiments, water diffusion in resin and polymer composites were characterized. Parameters for Fickian diffusion and polymer relaxation models were ...

  18. Using BIG data in transport modelling

    NARCIS (Netherlands)

    De Romph, E.

    2013-01-01

    Both innovation and ingenuity are required to turn an increasing amount of data that is not obviously 'transport oriented' into useful information that can assist with model building in circumstances where relevant data is otherwise not available or in poor supply, explains Omnitrans'

  19. A depth integrated model for suspended transport

    NARCIS (Netherlands)

    Galappatti, R.

    1983-01-01

    A new depth averaged model for suspended sediment transport in open channels has been developed based on an asymptotic solution to the two dimensional convection-diffusion equation in the vertical plane. The solution for the depth averaged concentration is derived from the bed boundary condition and

  20. Logistics Chains in Freight Transport Modelling

    NARCIS (Netherlands)

    Davydenko, I.Y.

    2015-01-01

    The flow of trade is not equal to transport flows, mainly due to the fact that warehouses and distribution facilities are used as intermediary stops on the way from production locations to the points of consumption or further rework of goods. This thesis proposes a logistics chain model, which

  1. Unreliability effects in public transport modelling.

    NARCIS (Netherlands)

    van Oort, Niels; Brands, Ties; de Romph, Erik; Aceves Flores, Jessica

    2015-01-01

    Nowadays, transport demand models do not explicitly evaluate the impacts of service reliability of transit. Service reliability of transit systems is adversely experienced by users, as it causes additional travel time and unsecure arrival times. Because of this, travellers are likely to perceive a

  2. Cumulus parameterizations in chemical transport models

    Science.gov (United States)

    Mahowald, Natalie M.; Rasch, Philip J.; Prinn, Ronald G.

    1995-12-01

    Global three-dimensional chemical transport models (CTMs) are valuable tools for studying processes controlling the distribution of trace constituents in the atmosphere. A major uncertainty in these models is the subgrid-scale parametrization of transport by cumulus convection. This study seeks to define the range of behavior of moist convective schemes and point toward more reliable formulations for inclusion in chemical transport models. The emphasis is on deriving convective transport from meteorological data sets (such as those from the forecast centers) which do not routinely include convective mass fluxes. Seven moist convective parameterizations are compared in a column model to examine the sensitivity of the vertical profile of trace gases to the parameterization used in a global chemical transport model. The moist convective schemes examined are the Emanuel scheme [Emanuel, 1991], the Feichter-Crutzen scheme [Feichter and Crutzen, 1990], the inverse thermodynamic scheme (described in this paper), two versions of a scheme suggested by Hack [Hack, 1994], and two versions of a scheme suggested by Tiedtke (one following the formulation used in the ECMWF (European Centre for Medium-Range Weather Forecasting) and ECHAM3 (European Centre and Hamburg Max-Planck-Institut) models [Tiedtke, 1989], and one formulated as in the TM2 (Transport Model-2) model (M. Heimann, personal communication, 1992). These convective schemes vary in the closure used to derive the mass fluxes, as well as the cloud model formulation, giving a broad range of results. In addition, two boundary layer schemes are compared: a state-of-the-art nonlocal boundary layer scheme [Holtslag and Boville, 1993] and a simple adiabatic mixing scheme described in this paper. Three tests are used to compare the moist convective schemes against observations. Although the tests conducted here cannot conclusively show that one parameterization is better than the others, the tests are a good measure of the

  3. Modelling radionuclide transport in highly heterogeneous media and under variable hydrochemical conditions using a "dynamic Kd" approach

    Science.gov (United States)

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

    2015-04-01

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

  4. Numerical modelling of ion transport in flames

    KAUST Repository

    Han, Jie

    2015-10-20

    This paper presents a modelling framework to compute the diffusivity and mobility of ions in flames. The (n, 6, 4) interaction potential is adopted to model collisions between neutral and charged species. All required parameters in the potential are related to the polarizability of the species pair via semi-empirical formulas, which are derived using the most recently published data or best estimates. The resulting framework permits computation of the transport coefficients of any ion found in a hydrocarbon flame. The accuracy of the proposed method is evaluated by comparing its predictions with experimental data on the mobility of selected ions in single-component neutral gases. Based on this analysis, the value of a model constant available in the literature is modified in order to improve the model\\'s predictions. The newly determined ion transport coefficients are used as part of a previously developed numerical approach to compute the distribution of charged species in a freely propagating premixed lean CH4/O2 flame. Since a significant scatter of polarizability data exists in the literature, the effects of changes in polarizability on ion transport properties and the spatial distribution of ions in flames are explored. Our analysis shows that changes in polarizability propagate with decreasing effect from binary transport coefficients to species number densities. We conclude that the chosen polarizability value has a limited effect on the ion distribution in freely propagating flames. We expect that the modelling framework proposed here will benefit future efforts in modelling the effect of external voltages on flames. Supplemental data for this article can be accessed at http://dx.doi.org/10.1080/13647830.2015.1090018. © 2015 Taylor & Francis.

  5. Symposium on unsaturated flow and transport modeling

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, E.M.; Gee, G.W.; Nelson, R.W. (eds.)

    1982-09-01

    This document records the proceedings of a symposium on flow and transport processes in partially saturated groundwater systems, conducted at the Battelle Seattle Research Center on March 22-24, 1982. The symposium was sponsored by the US Nuclear Regulatory Commission for the purpose of assessing the state-of-the-art of flow and transport modeling for use in licensing low-level nuclear waste repositories in partially saturated zones. The first day of the symposium centered around research in flow through partially saturated systems. Papers were presented with the opportunity for questions following each presentation. In addition, after all the talks, a formal panel discussion was held during which written questions were addressed to the panel of the days speakers. The second day of the Symposium was devoted to solute and contaminant transport in partially saturated media in an identical format. Individual papers are abstracted.

  6. Fractional diffusion models of nonlocal transport

    Energy Technology Data Exchange (ETDEWEB)

    Del-Castillo-Negrete, Diego B [ORNL

    2006-08-01

    A class of nonlocal models based on the use of fractional derivatives (FDs) is proposed to describe nondiffusive transport in magnetically confined plasmas. FDs are integro-differential operators that incorporate in a unified framework asymmetric non-Fickian transport, non-Markovian ('memory') effects, and nondiffusive scaling. To overcome the limitations of fractional models in unbounded domains, we use regularized FDs that allow the incorporation of finite-size domain effects, boundary conditions, and variable diffusivities. We present an alpha-weighted explicit/implicit numerical integration scheme based on the Grunwald-Letnikov representation of the regularized fractional diffusion operator in flux conserving form. In sharp contrast with the standard diffusive model, the strong nonlocality of fractional diffusion leads to a linear in time response for a decaying pulse at short times. In addition, an anomalous fractional pinch is observed, accompanied by the development of an uphill transport region where the 'effective' diffusivity becomes negative. The fractional flux is in general asymmetric and, for steady states, it has a negative (toward the core) component that enhances confinement and a positive component that increases toward the edge and leads to poor confinement. The model exhibits the characteristic anomalous scaling of the confinement time, {tau}, with the system's size, L, {tau}{approx}L{sup {alpha}}, of low-confinement mode plasma where 1<{alpha}<2 is the order of the FD operator. Numerical solutions of the model with an off-axis source show that the fractional inward transport gives rise to profile peaking reminiscent of what is observed in tokamak discharges with auxiliary off-axis heating. Also, cold-pulse perturbations to steady states in the model exhibit fast, nondiffusive propagation phenomena that resemble perturbative experiments.

  7. Fractional diffusion models of nonlocal transport

    Science.gov (United States)

    del-Castillo-Negrete, D.

    2006-08-01

    A class of nonlocal models based on the use of fractional derivatives (FDs) is proposed to describe nondiffusive transport in magnetically confined plasmas. FDs are integro-differential operators that incorporate in a unified framework asymmetric non-Fickian transport, non-Markovian ("memory") effects, and nondiffusive scaling. To overcome the limitations of fractional models in unbounded domains, we use regularized FDs that allow the incorporation of finite-size domain effects, boundary conditions, and variable diffusivities. We present an α-weighted explicit/implicit numerical integration scheme based on the Grunwald-Letnikov representation of the regularized fractional diffusion operator in flux conserving form. In sharp contrast with the standard diffusive model, the strong nonlocality of fractional diffusion leads to a linear in time response for a decaying pulse at short times. In addition, an anomalous fractional pinch is observed, accompanied by the development of an uphill transport region where the "effective" diffusivity becomes negative. The fractional flux is in general asymmetric and, for steady states, it has a negative (toward the core) component that enhances confinement and a positive component that increases toward the edge and leads to poor confinement. The model exhibits the characteristic anomalous scaling of the confinement time, τ, with the system's size, L, τ ˜Lα, of low-confinement mode plasma where 1<α<2 is the order of the FD operator. Numerical solutions of the model with an off-axis source show that the fractional inward transport gives rise to profile peaking reminiscent of what is observed in tokamak discharges with auxiliary off-axis heating. Also, cold-pulse perturbations to steady sates in the model exhibit fast, nondiffusive propagation phenomena that resemble perturbative experiments.

  8. Mesoscopic Modeling of Reactive Transport Processes

    Science.gov (United States)

    Kang, Q.; Chen, L.; Deng, H.

    2012-12-01

    Reactive transport processes involving precipitation and/or dissolution are pervasive in geochemical, biological and engineered systems. Typical examples include self-assembled patterns such as Liesegang rings or bands, cones of stalactites in limestones caves, biofilm growth in aqueous environment, formation of mineral deposits in boilers and heat exchangers, uptake of toxic metal ions from polluted water by calcium carbonate, and mineral trapping of CO2. Compared to experimental studies, a numerical approach enables a systematic study of the reaction kinetics, mass transport, and mechanisms of nucleation and crystal growth, and hence provides a detailed description of reactive transport processes. In this study, we enhance a previously developed lattice Boltzmann pore-scale model by taking into account the nucleation process, and develop a mesoscopic approach to simulate reactive transport processes involving precipitation and/or dissolution of solid phases. The model is then used to simulate the formation of Liesegang precipitation patterns and investigate the effects of gel on the morphology of the precipitates. It is shown that this model can capture the porous structures of the precipitates and can account for the effects of the gel concentration and material. A wide range of precipitation patterns is predicted under different gel concentrations, including regular bands, treelike patterns, and for the first time with numerical models, transition patterns from regular bands to treelike patterns. The model is also applied to study the effect of secondary precipitate on the dissolution of primary mineral. Several types of dissolution and precipitation processes are identified based on the morphology and structures of the precipitates and on the extent to which the precipitates affect the dissolution of the primary mineral. Finally the model is applied to study the formation of pseudomorph. It is demonstrated for the first time by numerical simulation that a

  9. Reactive-transport modeling of fly ash-wate-brines interactions from laboratory-scale column studies

    Science.gov (United States)

    Mbugua, John M.; Catherine Ngila, J.; Kindness, Andrew; Demlie, Molla

    Dynamic leaching tests are important studies that provide more insights into time-dependent leaching mechanisms of any given solid waste. Hydrogeochemical modeling using PHREEQC was applied for column modeling of two ash recipes and brines generated from South African coal utility plants, Sasol and Eskom. The modeling results were part of a larger ash-brine study aimed at acquiring knowledge on (i) quantification and characterization of the products formed when ash is in contact with wate-brines in different scenarios, (ii) the mineralogical changes associated with wate-brine-ash interactions over time, (iii) species concentration, and (iv) leaching and transport controlling factors. The column modeling was successfully identified and quantified as important reactive mineralogical phases controlling major, minor and trace elements' release. The pH of the solution was found to be a very important controlling factor in leaching chemistry. The highest mineralogical transformation took place in the first 10 days of ash contact with either water or brines, and within 0.1 m from the column inflow. Many of the major and trace elements Ca, Mg, Na, K, Sr, S(VI), Fe, are leached easily into water systems and their concentration fronts were high at the beginning (within 0.1 m from the column inflow and within the first 10 days) upon contact with the liquid phase. However, their concentration decreased with time until a steady state was reached. Modeling results also revealed that geochemical reactions taking place during ash-wate-brine interactions does affect the porosity of the ash, whereas the leaching processes lead to increased porosity. Besides supporting experimental data, modeling results gave predictive insights on leaching of elements which may directly impact on the environment, particularly ground water. These predictions will help develop scenarios and offer potential guide for future sustainable waste management practices as a way of addressing the co

  10. Modelling an Ammonium Transporter with SCLS

    Directory of Open Access Journals (Sweden)

    Angelo Troina

    2009-10-01

    Full Text Available The Stochastic Calculus of Looping Sequences (SCLS is a recently proposed modelling language for the representation and simulation of biological systems behaviour. It has been designed with the aim of combining the simplicity of notation of rewrite systems with the advantage of compositionality. It also allows a rather simple and accurate description of biological membranes and their interactions with the environment.In this work we apply SCLS to model a newly discovered ammonium transporter. This transporter is believed to play a fundamental role for plant mineral acquisition, which takes place in the arbuscular mycorrhiza, the most wide-spread plant-fungus symbiosis on earth. Due to its potential application in agriculture this kind of symbiosis is one of the main focuses of the BioBITs project. In our experiments the passage of NH3 / NH4+ from the fungus to the plant has been dissected in known and hypothetical mechanisms; with the model so far we have been able to simulate the behaviour of the system under different conditions. Our simulations confirmed some of the latest experimental results about the LjAMT2;2 transporter. The initial simulation results of the modelling of the symbiosis process are promising and indicate new directions for biological investigations.

  11. Progress in unsaturated flow and transport modeling

    Science.gov (United States)

    van Genuchten, Martinus Th.; Jury, William A.

    1987-03-01

    This paper reviews recent progress in modeling water flow and solute transport in the unsaturated (vadose) zone. Much progress has been attained in the analytical and numerical description of vadose zone transfer processes. A variety of deterministic models are currently available for describing and predicting these processes. The most popular ones continue to be the classical Richards equation for unsaturated flow and the Fickian-based convection-dispersion equation for solute transport. While deterministic solutions of these equations remain useful tools in research and management, their practical utility for predicting actual field water and solute concentration is increasingly being questioned. Problems caused by preferential flow through soil macropores and by spatial and temporal variability in soil hydraulic properties have caused some disillusionment with the classical models. A number of alternative deterministic and stochastic formulations have been proposed to specifically deal with preferential flow and/or spatial variability. Those models have greatly increased our understanding of field scale transport processes, and have in some cases led to better practical tools for management purposes.

  12. HYDROGEOCHEMICAL CHARACTERISTICS OF THE ST. IVAN SPRING IN ISTRIA, CROATIA

    Directory of Open Access Journals (Sweden)

    Tatjana Vlahović

    2000-12-01

    Full Text Available In addition to geological, hydrogeological investigations and groundwater tracing, detailed surveying of the groundwater quality is becoming particularly important for environmental impact monitoring on karst aquifers. Groundwater quality data contain two types of information i.e. the natural chemistry of water and its modifications caused by antropogenic impacts. The method of results presentation as well as the importance of water quality surveying particularly with respect to the indicators showing its natural chemistry, are shown here exemplified by the St. Ivan spring in Istria, Croatia. Natural chemistry of the groundwater is a consequence of hydrogeochemical facies, and it is used here for interpretation of spring generating conditions and the origin of groundwater. Results obtained so far confirm that the extent of recharge area of the spring change in dependence of the hydrological conditions. Hydrogeochemical characteristics of the spring are presented graphically in the form of correlation diagrams showing major groundwater parameters, saturation conditions and trends of particular parameters as a function of time.

  13. Modelling sediment clasts transport during landscape evolution

    Science.gov (United States)

    Carretier, Sébastien; Martinod, Pierre; Reich, Martin; Godderis, Yves

    2016-03-01

    Over thousands to millions of years, the landscape evolution is predicted by models based on fluxes of eroded, transported and deposited material. The laws describing these fluxes, corresponding to averages over many years, are difficult to prove with the available data. On the other hand, sediment dynamics are often tackled by studying the distribution of certain grain properties in the field (e.g. heavy metals, detrital zircons, 10Be in gravel, magnetic tracers). There is a gap between landscape evolution models based on fluxes and these field data on individual clasts, which prevent the latter from being used to calibrate the former. Here we propose an algorithm coupling the landscape evolution with mobile clasts. Our landscape evolution model predicts local erosion, deposition and transfer fluxes resulting from hillslope and river processes. Clasts of any size are initially spread in the basement and are detached, moved and deposited according to probabilities using these fluxes. Several river and hillslope laws are studied. Although the resulting mean transport rate of the clasts does not depend on the time step or the model cell size, our approach is limited by the fact that their scattering rate is cell-size-dependent. Nevertheless, both their mean transport rate and the shape of the scattering-time curves fit the predictions. Different erosion-transport laws generate different clast movements. These differences show that studying the tracers in the field may provide a way to establish these laws on the hillslopes and in the rivers. Possible applications include the interpretation of cosmogenic nuclides in individual gravel deposits, provenance analyses, placers, sediment coarsening or fining, the relationship between magnetic tracers in rivers and the river planform, and the tracing of weathered sediment.

  14. Improving Estuarine Transport Models using Satellite Measurements

    Science.gov (United States)

    2013-09-30

    river flow, low energy neap tides. Spatial variability is also evident, with shallow water regions along the fringe and at upstream intertidal areas ...processes that produce remotely-sensed surface patterns provides a means for testing and improving transport models, particularly in areas in which...flanked by intertidal flats. As with field and satellite data, the shape of the turbidity maximum is asymmetric, and the position is related to the

  15. Energy transport modelling including ergodic effects

    Energy Technology Data Exchange (ETDEWEB)

    McTaggart, N.; Bonnin, X.; Runov, A.; Schneider, R. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Wendelsteinstrasse 1, D-17491 Greifswald (Germany); Zagorski, R. [Institute of Plasma Physics and Laser Microfusion, P.O.Box 49, Warsaw (Poland)

    2004-04-01

    The effect of ergodization (either by additional coils like in TEXTOR-DED or by intrinsic plasma effects like in W7-X) defines the need for transport models being able to describe this properly. A prerequisite for this is the concept of local magnetic coordinates allowing a correct discretization with minimized numerical errors. For these coordinates the full respective metric tensor has to be known. To study the energy transport in complex edge geometries (in particular for W7-X) we use a finite difference discretization of the transport equations on a custom-tailored grid in local magnetic coordinates. This grid is generated by field line tracing to guarantee an exact discretization of the dominant parallel transport (this also minimizes the numerical diffusion problem). The perpendicular fluxes are interpolated on cross-sectional planes (toroidal cuts), where a quasi-isotropic problem is solved by a constrained Delaunay triangulation (preserving magnetic surfaces where they exist), and discretization. All terms involving toroidal terms are discretized by finite differences. The first tests for W7X and NCSX were successfully performed. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Transportation planning, management systems, public participation, and land use modeling. Transportation research record

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-12-31

    This volume focuses on statewide and metropolitan transportation planning, management systems, and land use-transportation issues. The papers on statewide and metropolitan transportation planning concern an interactive planning modeling process (Wyoming), an area transportation partnership to assist in the development of the state transportation improvement program (Minnesota), the development of a customer perspective in the statewide transportation planning process (Colorado), a pilot transportation plan for an Indian reservation in western North Carolina, and a community-based, strategic, comprehensive planning process (Ithaca, New York). The papers that concern management systems fall into two categories: those which discuss congestion management and those which discuss management systems for transport infrastructure.

  17. Thermal Transport Model for Heat Sink Design

    Science.gov (United States)

    Chervenak, James A.; Kelley, Richard L.; Brown, Ari D.; Smith, Stephen J.; Kilbourne, Caroline a.

    2009-01-01

    A document discusses the development of a finite element model for describing thermal transport through microcalorimeter arrays in order to assist in heat-sinking design. A fabricated multi-absorber transition edge sensor (PoST) was designed in order to reduce device wiring density by a factor of four. The finite element model consists of breaking the microcalorimeter array into separate elements, including the transition edge sensor (TES) and the silicon substrate on which the sensor is deposited. Each element is then broken up into subelements, whose surface area subtends 10 10 microns. The heat capacity per unit temperature, thermal conductance, and thermal diffusivity of each subelement are the model inputs, as are the temperatures of each subelement. Numerical integration using the Finite in Time Centered in Space algorithm of the thermal diffusion equation is then performed in order to obtain a temporal evolution of the subelement temperature. Thermal transport across interfaces is modeled using a thermal boundary resistance obtained using the acoustic mismatch model. The document concludes with a discussion of the PoST fabrication. PoSTs are novel because they enable incident x-ray position sensitivity with good energy resolution and low wiring density.

  18. Understanding transport in model water desalination membranes

    Science.gov (United States)

    Chan, Edwin

    Polyamide based thin film composites represent the the state-of-the-art nanofiltration and reverse osmosis membranes used in water desalination. The performance of these membranes is enabled by the ultrathin (~100 nm) crosslinked polyamide film in facilitating the selective transport of water over salt ions. While these materials have been refined over the last several decades, understanding the relationships between polyamide structure and membrane performance remains a challenge because of the complex and heterogeneous nature of the polyamide film. In this contribution, we present our approach to addressing this challenge by studying the transport properties of model polyamide membranes synthesized via molecular layer-by-layer (mLbL) assembly. First, we demonstrate that mLbL can successfully construct polyamide membranes with well-defined nanoscale thickness and roughness using a variety of monomer formulations. Next, we present measurement tools for characterizing the network structure and transport of these model polyamide membranes. Specifically, we used X-ray and neutron scattering techniques to characterize their structure as well as a recently-developed indentation based poromechanics approach to extrapolate their water diffusion coefficient. Finally, we illustrate how these measurements can provide insight into the original problem by linking the key polyamide network properties, i.e. water-polyamide interaction parameter and characteristic network mesh size, to the membrane performance.

  19. Transport modeling: An artificial immune system approach

    Directory of Open Access Journals (Sweden)

    Teodorović Dušan

    2006-01-01

    Full Text Available This paper describes an artificial immune system approach (AIS to modeling time-dependent (dynamic, real time transportation phenomenon characterized by uncertainty. The basic idea behind this research is to develop the Artificial Immune System, which generates a set of antibodies (decisions, control actions that altogether can successfully cover a wide range of potential situations. The proposed artificial immune system develops antibodies (the best control strategies for different antigens (different traffic "scenarios". This task is performed using some of the optimization or heuristics techniques. Then a set of antibodies is combined to create Artificial Immune System. The developed Artificial Immune transportation systems are able to generalize, adapt, and learn based on new knowledge and new information. Applications of the systems are considered for airline yield management, the stochastic vehicle routing, and real-time traffic control at the isolated intersection. The preliminary research results are very promising.

  20. Integrated urban systems model with multiple transportation supply agents.

    Science.gov (United States)

    2012-10-01

    This project demonstrates the feasibility of developing quantitative models that can forecast future networks under : current and alternative transportation planning processes. The current transportation planning process is modeled : based on empiric...

  1. Microbial respiration and dissolution precipitation reactions of minerals: thermo-kinetics and reactive transport modelling

    Science.gov (United States)

    Azaroual, M. M.; Parmentier, M.; Andre, L.; Croiset, N.; Pettenati, M.; Kremer, S.

    2010-12-01

    Microbial processes interact closely with abiotic geochemical reactions and mineralogical transformations in several hydrogeochemical systems. Reactive transport models are aimed to analyze these complex mechanisms integrating as well as the degradation of organic matter as the redox reactions involving successive terminal electron acceptors (TEAPs) mediated by microbes through the continuum of unsaturated zone (soil) - saturated zone (aquifer). The involvement of microbial processes in reactive transport in soil and subsurface geologic greatly complicates the mastery of the major mechanisms and the numerical modelling of these systems. The introduction of kinetic constraints of redox reactions in aqueous phase requires the decoupling of equilibrium reactions and the redefinition of mass balance of chemical elements including the concept of basis species and secondary species of thermodynamic databases used in geochemical modelling tools. An integrated methodology for modelling the reactive transport has been developed and implemented to simulate the transfer of arsenic, denitrification processes and the role of metastable aqueous sulfur species with pyrite and organic matter as electron donors entities. A mechanistic rate law of microbial respiration in various geochemical environments was used to simulate reactive transport of arsenic, nitrate and organic matter combined to the generalized rate law of mineral dissolution - precipitation reactions derived from the transition state theory was used for dissolution - precipitation of silica, aluminosilicate, carbonate, oxyhydroxide, and sulphide minerals. The kinetic parameters are compiled from the literature measurements based on laboratory constrained experiments and field observations. Numerical simulations, using the geochemical software PHREEQC, were performed aiming to identify the key reactions mediated by microbes in the framework of in the first hand the concept of the unsaturated - saturated zones of an

  2. A disaggregate freight transport model of transport chain and shipment size choice

    NARCIS (Netherlands)

    Windisch, E.; De Jong, G.C.; Van Nes, R.; Hoogendoorn, S.P.

    2010-01-01

    The field of freight transport modelling is relatively young compared to passenger transport modelling. However, some key issues in freight policy, like growing freight shares on the road, advanced logistics concepts or emerging strict freight transport regulations, have been creating increasing

  3. Modeling in transport phenomena a conceptual approach

    CERN Document Server

    Tosun, Ismail

    2007-01-01

    Modeling in Transport Phenomena, Second Edition presents and clearly explains with example problems the basic concepts and their applications to fluid flow, heat transfer, mass transfer, chemical reaction engineering and thermodynamics. A balanced approach is presented between analysis and synthesis, students will understand how to use the solution in engineering analysis. Systematic derivations of the equations and the physical significance of each term are given in detail, for students to easily understand and follow up the material. There is a strong incentive in science and engineering to

  4. Task force on modelling of groundwater flow and transport of solutes. Task 5 Summary report

    Energy Technology Data Exchange (ETDEWEB)

    Rhen, Ingvar [SWECO VIAK AB, Goeteborg (Sweden); Smellie, John [Conterra AB, Uppsala (Sweden)

    2003-02-01

    The Aespoe Hard Rock Laboratory is located in the Simpevarp area, southeast Sweden, some 35 km north of Oskarshamn. Construction of the underground laboratory commenced in 1990 and was completed in 1995, consisting of a 3.6 km. long tunnel excavated in crystalline rock to a depth of approximately 460 m. Prior to, during and subsequent to completion, research concerning the deep geological disposal of nuclear waste in fractured crystalline rock has been carried out. Central to this research has been the characterisation of the groundwater flow system and the chemistry of the groundwaters at Aespoe prior to excavation (Pre-investigation Phase) and subsequently to monitor changes in these parameters during the evolution of laboratory construction (Construction Phase). The principle aim of the Aespoe Task 5 modelling exercise has been to compare and ultimately integrate hydrogeochemistry and hydrogeology using the input data from the pre-investigation and construction phases. The main objectives were: to assess the consistency of groundwater-flow models and hydrogeochemical mixing-reaction models through integration and comparison of hydraulic and hydrogeochemical data obtained before and during tunnel construction, and to develop a procedure for integration of hydrological and hydrogeochemical information which could be used for disposal site assessments. Task 5 commenced in 1998 and was finalised in 2002. Participating modelling teams in the project represented ANDRA (France; three modelling teams - ANTEA, ITASCA, CEA), BMWi/BGR (Germany), ENRESA (Spain), JNC (Japan), CRIEPI (Japan), Posiva (Finland) and SKB (Sweden; two modelling teams - CFE and Intera (now GeoPoint)). Experience from Task 5 has highlighted several important aspects for site investigations facilitating the possibilities for mathematically integrated modelling and consistency checks that should be taken into account for future repository performance assessments. Equally important is that Task 5 has

  5. Documentation of TRU biological transport model (BIOTRAN)

    Energy Technology Data Exchange (ETDEWEB)

    Gallegos, A.F.; Garcia, B.J.; Sutton, C.M.

    1980-01-01

    Inclusive of Appendices, this document describes the purpose, rationale, construction, and operation of a biological transport model (BIOTRAN). This model is used to predict the flow of transuranic elements (TRU) through specified plant and animal environments using biomass as a vector. The appendices are: (A) Flows of moisture, biomass, and TRU; (B) Intermediate variables affecting flows; (C) Mnemonic equivalents (code) for variables; (D) Variable library (code); (E) BIOTRAN code (Fortran); (F) Plants simulated; (G) BIOTRAN code documentation; (H) Operating instructions for BIOTRAN code. The main text is presented with a specific format which uses a minimum of space, yet is adequate for tracking most relationships from their first appearance to their formulation in the code. Because relationships are treated individually in this manner, and rely heavily on Appendix material for understanding, it is advised that the reader familiarize himself with these materials before proceeding with the main text.

  6. Parameter optimization for surface flux transport models

    Science.gov (United States)

    Whitbread, T.; Yeates, A. R.; Muñoz-Jaramillo, A.; Petrie, G. J. D.

    2017-11-01

    Accurate prediction of solar activity calls for precise calibration of solar cycle models. Consequently we aim to find optimal parameters for models which describe the physical processes on the solar surface, which in turn act as proxies for what occurs in the interior and provide source terms for coronal models. We use a genetic algorithm to optimize surface flux transport models using National Solar Observatory (NSO) magnetogram data for Solar Cycle 23. This is applied to both a 1D model that inserts new magnetic flux in the form of idealized bipolar magnetic regions, and also to a 2D model that assimilates specific shapes of real active regions. The genetic algorithm searches for parameter sets (meridional flow speed and profile, supergranular diffusivity, initial magnetic field, and radial decay time) that produce the best fit between observed and simulated butterfly diagrams, weighted by a latitude-dependent error structure which reflects uncertainty in observations. Due to the easily adaptable nature of the 2D model, the optimization process is repeated for Cycles 21, 22, and 24 in order to analyse cycle-to-cycle variation of the optimal solution. We find that the ranges and optimal solutions for the various regimes are in reasonable agreement with results from the literature, both theoretical and observational. The optimal meridional flow profiles for each regime are almost entirely within observational bounds determined by magnetic feature tracking, with the 2D model being able to accommodate the mean observed profile more successfully. Differences between models appear to be important in deciding values for the diffusive and decay terms. In like fashion, differences in the behaviours of different solar cycles lead to contrasts in parameters defining the meridional flow and initial field strength.

  7. Ecosystem element transport model for Lake Eckarfjaerden

    Energy Technology Data Exchange (ETDEWEB)

    Konovalenko, L.; Bradshaw, C. [The Department of Ecology, Environment and Plant Sciences, Stockholm University (Sweden); Andersson, E.; Kautsky, U. [Swedish Nuclear Fuel and Waste Management Co. - SKB (Sweden)

    2014-07-01

    The ecosystem transport model of elements was developed for Lake Eckarfjaerden located in the Forsmark area in Sweden. Forsmark has currently a low level repository (SFR) and a repository for spent fuel is planned. A large number of data collected during site-investigation program 2002-2009 for planning the repository were available for the creation of the compartment model based on carbon circulation, physical and biological processes (e.g. primary production, consumption, respiration). The model is site-specific in the sense that the food web model is adapted to the actual food web at the site, and most estimates of biomass and metabolic rates for the organisms and meteorological data originate from site data. The functional organism groups of Lake Eckarfjaerden were considered as separate compartments: bacterio-plankton, benthic bacteria, macro-algae, phytoplankton, zooplankton, fish, benthic fauna. Two functional groups of bacteria were taken into account for the reason that they have the highest biomass of all functional groups during the winter, comprising 36% of the total biomass. Effects of ecological parameters, such as bacteria and algae biomass, on redistribution of a hypothetical radionuclide release in the lake were examined. The ecosystem model was used to estimate the environmental transfer of several elements (U, Th, Ra) and their isotopes (U-238, U-234,Th-232, Ra-226) to various aquatic organisms in the lake, using element-specific distribution coefficients for suspended particle and sediment. Results of chemical analyses of the water, sediment and biota were used for model validation. The model gives estimates of concentration factors for fish based on modelling rather on in situ measurement, which reduces the uncertainties for many radionuclides with scarce of data. Document available in abstract form only. (authors)

  8. Complexities in coastal sediment transport studies by numerical modelling

    Digital Repository Service at National Institute of Oceanography (India)

    Ilangovan, D.; ManiMurali, R.

    Marine environmental studies related to erosion, accretion, pollution transport, dredge disposal, location of seawater intake, effluent disposal, etc., involve sediment transport studies. Numerical models use set of well linked mathematical...

  9. Modelling the transport system in China and evaluating the current strategies towards the sustainable transport development

    DEFF Research Database (Denmark)

    Liu, W.; Lund, H.; Mathiesen, B.V.

    2013-01-01

    Transport is one of the most challenge sectors when addressing energy security and climate change due to its high reliance on oil products and lack of the alternative fuels. This paper explores the ability of three transport strategies to contribute to the development of a sustainable transport...... in China. With this purpose in mind, a Chinese transport model has been created and three current transport strategies which are high speed railway (HSR), urban rail transit (URT) and electric vehicle (EV) were evaluated together with a reference transport system in 2020. As conservative results, 13...

  10. Neutral gas transport modeling with DEGAS 2

    Energy Technology Data Exchange (ETDEWEB)

    Stotler, D.; Karney, C.

    1993-10-01

    We are currently rewriting the neutral gas transport code, DEGAS with a view to not only making it faster, but also easing the process of including new physics. The goal is to make adding new species and reactions relatively simple so that the code can be rapidly adapted to new divertor physics regimes. DEGAS 2 will also be optimized for coupling to fluid plasma codes, incorporating many of the techniques utilized in B2-EIRENE. Finally, it is our intention that DEGAS 2, like DEGAS, be well-documented and easy to use. We ill present model calculations including ionization and charge exchange which will illustrate the way reactions are included into DEGAS 2 and will demonstrate operation of the code on a distributed network of workstations.

  11. Modeling Oxygen Transport in the Human Placenta

    Science.gov (United States)

    Serov, Alexander; Filoche, Marcel; Salafia, Carolyn; Grebenkov, Denis

    Efficient functioning of the human placenta is crucial for the favorable pregnancy outcome. We construct a 3D model of oxygen transport in the placenta based on its histological cross-sections. The model accounts for both diffusion and convention of oxygen in the intervillous space and allows one to estimate oxygen uptake of a placentone. We demonstrate the existence of an optimal villi density maximizing the uptake and explain it as a trade-off between the incoming oxygen flow and the absorbing villous surface. Calculations performed for arbitrary shapes of fetal villi show that only two geometrical characteristics - villi density and the effective villi radius - are required to predict fetal oxygen uptake. Two combinations of physiological parameters that determine oxygen uptake are also identified: maximal oxygen inflow of a placentone and the Damköhler number. An automatic image analysis method is developed and applied to 22 healthy placental cross-sections demonstrating that villi density of a healthy human placenta lies within 10% of the optimal value, while overall geometry efficiency is rather low (around 30-40%). In a perspective, the model can constitute the base of a reliable tool of post partum oxygen exchange efficiency assessment in the human placenta. Also affiliated with Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA 90095, USA.

  12. Contaminant transport at a waste residue deposit: 1. Inverse flow and non-reactive transport modelling

    DEFF Research Database (Denmark)

    Sonnenborg, Torben Obel; Engesgaard, Peter Knudegaard; Rosbjerg, Dan

    1996-01-01

    An application of an inverse flow and transport model to a contaminated aquifer is presented. The objective of the study is to identify physical and nonreactive flow and transport parameters through an optimization approach. The approach can be classified as a statistical procedure, where a flow ...... is the first in a two-paper series describing contaminant transport at a waste residue site. III the second paper, reactive transport at the site is investigated....

  13. Hydrogeochemical precursors of strong earthquakes in Kamchatka: further analysis

    Directory of Open Access Journals (Sweden)

    P. F. Biagi

    2001-01-01

    Full Text Available For many years, ion and gas content data have been collected from the groundwater of three deep wells in the southern area of the Kamchatka peninsula, Russia. In the last ten years, five earthquakes with M > 6.5 have occurred within 250 km of the wells. In a previous study, we investigated the possibility that the hydrogeochemical time series contained precursors. The technique used was to assume that each signal with an amplitude of three times the standard deviation is an irregularity and we then defined anomalies as irregularities occurring simultaneously in the data for more than one parameter at each well. Using this method, we identified 11 anomalies with 8 of them being possible successes and 3 being failures as earthquake precursors. Precursors were obtained for all five earthquakes that we considered. In this paper, we allow for the cross-correlation found between the gas data sets and in some cases, between the ion data sets. No cross-correlation has been found between gas and ion content data. Any correlation undermines the idea that an anomaly might be identified from irregularities appearing simultaneously on different parameters at each site. To refine the technique, we re-examine the hydrogeochemical data and define as anomalies those irregularities occurring simultaneously only in the data of two or more uncorrelated parameters. We then restricted the analysis to the cases of just the gas content data and the ion content data. In the first case, we found 6 successes and 2 failures, and in the second case, we found only 3 successes. In the first case, the precursors appear only for three of the five earthquakes we considered, and in the second case, only for two, but these are the earthquakes nearest to the wells. Interestingly, it shows that when a strict set of rules for defining an anomaly is used, the method produces only successes and when less restrictive rules are used, earthquakes further from the well are implicated, but

  14. Hydrogeological and hydrogeochemical characterization of a karstic mountain region

    Science.gov (United States)

    Simsek, Celalettin; Elci, Alper; Gunduz, Orhan; Erdogan, Burhan

    2008-03-01

    Karstic limestone formations in the Mediterranean basin are potential water resources that can meet a significant portion of groundwater demand. Therefore, it is necessary to thoroughly study the hydrogeology and hydrogeochemistry of karstic mountain regions. This paper presents a detailed hydrogeological and hydrogeochemical characterization of the Nif Mountain karstic aquifer system in western Turkey, an important recharge source for the densely populated surrounding area. Based on the geological and hydrogeological studies, four major aquifers were identified in the study area including the allochthonous limestone in Bornova flysch, conglomerate-sandstone and clayey-limestone in Neogene series, and the Quaternary alluvium. Physicochemical characteristics of groundwater were measured in situ, and samples were collected at 59 locations comprised of springs and wells. Samples were analyzed for major ions, isotopic composition, arsenic, boron and heavy metals among other trace elements. It was found that the hydrogeological structure is complex with many springs having a wide range of discharge rates. High-discharge springs originate from allochthonous limestone units, whereas low-discharge springs are formed at the contacts with claystone and limestone units. Using stable isotope analysis data, a δ18O-deuterium relationship was obtained that lies between the Mediterranean meteoric and mean global lines. Tritium analyses showed that low-discharge springs originating from contact zones had longer circulation times compared to the high-discharge karstic springs. Furthermore, hydrogeochemical data revealed that groundwater quality significantly deteriorated as water moved from the mountain to the plains. Heavy metal, arsenic and boron concentrations were generally within drinking-water quality standards with a few exceptions occurring in residential and industrial areas located at the foothills of the mountain. Elevated arsenic concentrations were related to local

  15. Survey of research reports in transportation modelling. Part 1

    NARCIS (Netherlands)

    Nijsse, A.; Wamsteker-Andriessen, S.J.

    1993-01-01

    A survey of research reports in transportation modelling in two parts. Part one is devided in reports concerning economic development and car mobility, analyzing large transportation data files and transportation planning and spatial development. Part two consists of reserach reports concerning

  16. Survey of research reports in transportation modelling. Part 2

    NARCIS (Netherlands)

    Nijsse, A.; Wamsteker-Andriessen, S.J.

    1993-01-01

    A survey of research reports in transportation modelling in two parts. Part one is devided in reports concerning economic development and car mobility, analyzing large transportation data files and transportation planning and spatial development. Part two consists of reserach reports concerning

  17. Modelling force deployment from army intelligence using the transportation system capability (TRANSCAP) model : a standardized approach

    National Research Council Canada - National Science Library

    Burke, J. F., Jr; Love, R. J; Macal, C. M

    2004-01-01

    ...) model to simulate the deployment of forces from Army bases, in collaboration with and under the sponsorship of the Military Transportation Management Command Transportation Engineering Agency (MTMCTEA...

  18. Visualization and modeling of smoke transport over landscape scales

    Science.gov (United States)

    Glenn P. Forney; William Mell

    2007-01-01

    Computational tools have been developed at the National Institute of Standards and Technology (NIST) for modeling fire spread and smoke transport. These tools have been adapted to address fire scenarios that occur in the wildland urban interface (WUI) over kilometer-scale distances. These models include the smoke plume transport model ALOFT (A Large Open Fire plume...

  19. Modeling flow and solute transport in irrigation furrows

    Science.gov (United States)

    This paper presents an internally coupled flow and solute transport model for free-draining irrigation furrows. Furrow hydraulics is simulated with a numerical zero-inertia model and solute transport is computed with a model based on a numerical solution of the cross-section averaged advection-dispe...

  20. Modeling and analysis of transport in the mammary glands

    Science.gov (United States)

    Quezada, Ana; Vafai, Kambiz

    2014-08-01

    The transport of three toxins moving from the blood stream into the ducts of the mammary glands is analyzed in this work. The model predictions are compared with experimental data from the literature. The utility of the model lies in its potential to improve our understanding of toxin transport as a pre-disposing factor to breast cancer. This work is based on a multi-layer transport model to analyze the toxins present in the breast milk. The breast milk in comparison with other sampling strategies allows us to understand the mass transport of toxins once inside the bloodstream of breastfeeding women. The multi-layer model presented describes the transport of caffeine, DDT and cimetidine. The analysis performed takes into account the unique transport mechanisms for each of the toxins. Our model predicts the movement of toxins and/or drugs within the mammary glands as well as their bioaccumulation in the tissues.

  1. Transperitoneal transport of creatinine. A comparison of kinetic models

    DEFF Research Database (Denmark)

    Fugleberg, S; Graff, J; Joffe, P

    1994-01-01

    and lymphatic convective solute transport. The validation procedure included an assessment of theoretical (a priori) and practical (a posteriori) identifiability, goodness of fit, residual error analysis and plausibility of parameter estimates. The results of the validation procedure demonstrate that the model......Six kinetic models of transperitoneal creatinine transport were formulated and validated on the basis of experimental results obtained from 23 non-diabetic patients undergoing peritoneal dialysis. The models were designed to elucidate the presence or absence of diffusive, non-lymphatic convective...... including all three forms of transport is superior to other models. We conclude that the best model of transperitoneal creatinine transport includes diffusion, non-lymphatic convective transport and lymphatic convective transport....

  2. Modelling Emission of Pollutants from transportation using mobile sensing data

    DEFF Research Database (Denmark)

    Lehmann, Anders

    to use data acquired from smartphones to im- prove transportation related air quality models and models for climate gas emission from transportation. These models can be used for planning of transportation net- works, monitoring of air quality, and automate transport related green accounting. More...... of individual drivers, by deducing driving modes from accelerometer data. The work presented in this thesis spans different and diverse research fields. Trans- portation models are a subfield of econometrics, air quality modelling is a subfield of atmospheric chemistry, and driving mode detection and efficient...... database imple- mentations are a subfield of computer science. I have worked to bring these diverse research fields together to solve the challenge of improving modelling of transporta- tion related air quality emissions as well as modelling of transportation related climate gas emissions. The main...

  3. Thermal Transport in the Kitaev Model

    Science.gov (United States)

    Nasu, Joji; Yoshitake, Junki; Motome, Yukitoshi

    2017-09-01

    In conventional insulating magnets, heat is carried by magnons and phonons. In contrast, when the magnets harbor a quantum spin liquid state, emergent quasiparticles from the fractionalization of quantum spins can carry heat. Here, we investigate unconventional thermal transport yielded by such exotic carriers, in both longitudinal and transverse components, for the Kitaev model, whose ground state is exactly shown to be a quantum spin liquid with fractional excitations described as itinerant Majorana fermions and localized Z2 fluxes. We find that the longitudinal thermal conductivity exhibits a single peak at a high temperature, while the nonzero frequency component has a peak at a low temperature, reflecting the spin fractionalization. On the other hand, we show that the transverse thermal conductivity is induced by the magnetic field in a wide temperature range up to the energy scale of the bare exchange coupling; while increasing temperature, the transverse response divided by temperature decreases from the quantized value expected for the topologically nontrivial ground state and shows nonmonotonic temperature dependence. These characteristic behaviors provide experimentally accessible evidence of fractional excitations in the proximity to the Kitaev quantum spin liquid.

  4. Hydro-geophysical interpretation of fractured and karstified limestones reservoirs: A case study from Amdoun region (NW Tunisia) using electrical resistivity tomography, digital elevation model (DEM) and hydro-geochemical approaches

    Science.gov (United States)

    Redhaounia, Belgacem; Aktarakçi, Hasan; Ilondo, Batobo Ountsche; Gabtni, Hakim; Khomsi, Sami; Bédir, Mourad

    2015-12-01

    Groundwater from fractures and karst in limestone rocks is an important source of drinking water in the semi-arid climatic environment of North-Western Tunisia where cool and rainy seasons alternate with hot dry seasons. Due to varying climatic conditions and anthropogenic interventions the fractured limestone aquifer systems (Abiod and Boudabbous/El Gueria Formations) tend to be complex. The lack of data on the fractured and karstified aquifers in Amdoun region (NW Tunisia) to establish the hydrogeological potential between different rock formations of Upper Cretaceous and Lower Eocene has often discouraged researchers from attempting to model such aquifers. On the SE flank of the Jebel Sabbah anticline, Electrical Resistivity Tomography Data were collected along three different lines of 315 m of length each. The expected vertical penetration depth was 60 m. This hydro-geophysical investigation consisting of geological, structural, and geo-morphological studies, has demonstrated that groundwater in the carbonate rocks, in Amdoun area, occur in fracture zones and weathered parts of the rocks in the karst aquifers. The hydrochemical data (major ion geochemistry) indicate that these groundwaters are characterized by the dominance a Ca-Mg-HCO3 water type. Geochemical pattern is mainly controlled by the dissolution of carbonate minerals. Generally, TDS increases from the Amdoun Monts towards the discharge area (53 < TDS<332 mg l-1). These results are assessed using numerous geophysical data such as ERT imaging and geological knowledge. Finally, we show how these results could be used to improve the management of karst groundwater resources in Amdoun (NW Tunisia) complex terrain.

  5. Modelling global container freight transport demand

    NARCIS (Netherlands)

    Tavasszy, L.A.; Ivanova, O.; Halim, R.A.

    2015-01-01

    The objective of this chapter is to discuss methods and techniques for a quantitative and descriptive analysis of future container transport demand at a global level. Information on future container transport flows is useful for various purposes. It is instrumental for the assessment of returns of

  6. Modelling multicomponent solute transport in structured soils

    NARCIS (Netherlands)

    Beinum, van G.W.

    2007-01-01

    The mobility of contaminants in soil is an important factor in determining their ability to spread into the wider environment. For non-volatile substances, transport within the soil is generally dominated by transport of dissolved fractions in the soil water phase, via either diffusion or

  7. European initiatives for modeling emissions from transport

    DEFF Research Database (Denmark)

    Joumard, Robert; Hickman, A. John; Samaras, Zissis

    1998-01-01

    In Europe there have been many cooperative studies into transport emission inventories since the late 80s. These cover the scope of CORINAIR program involving experts from seven European Community laboratories addressing only road transport emissions at national level. These also include the late...

  8. A study on iron ore transportation model with penalty value of transportation equipment waiting

    Directory of Open Access Journals (Sweden)

    Kailing Pan

    2017-03-01

    Full Text Available As some steel enterprises are at a disadvantage in the choice of the mode of transportation, this paper made further studies of the characteristics of the iron ore logistics, taking comprehensive consideration of optimizing the waiting time under the conditions with limited loading capacity and setting up a procedural model of the iron ore logistics system with minimum cost of transportation, storage, loading, unloading, and transportation equipment waiting. Finally, taking the iron ore transport system of one steel enterprise as example, the solution and the validity of the model were analyzed and verified in this paper.

  9. Hydrogeochemical and Isotopic Study of Groundwaters from the Gañuelas-Mazarrón Tertiary Basin (Murcia, Spain); Estudio Hidrogeoquímico e Isotópico de las Aguas de la Cuenca Terciaria de Gañuelas-Mazarrón (Murcia, España)

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigo-Naharro, J.; Delgado, A.; Clemente-Jul, C.; Pérez del Villar, L.

    2015-07-01

    The hydrogeochemical characterisation of groundwaters from the Gañuelas-Mazarrón Tertiary Basin included: i) to establish the different hydrofacies present in the basin; ii) to perform a cluster analysis in order to reduce the water samples, grouping them according to their physicochemical characteristics; and iii) to determine the most relevant ion ratios for understanding the water/ rock interaction processes that regulate the main features and evolution of groundwaters. It has also been discussed the origin and concentration of the minor and trace elements to evaluate the capability of groundwaters to transport heavy elements, toxic or innocuous, towards the surface, thus determining their suitability for human consumption. Besides, the hydrogeochemical modeling has allowed determining the degree of groundwaters saturation with respect to the most representative mineral phases of the aquifers, which, in turn, it has been used to calculate their theoretical temperature in depth. The isotopic characterisation of groundwaters has included the isotopic signatures of the stable (δ18O, δ2H, δ13C-DIC, δ34S(SO4 2-) and δ18O(SO4 2-)) and radioactive (238U, 234U and 226Ra) isotopes. The first have been used to distinguish the groundwaters origin, as well as the origin of the dissolved C and SO4 2-. The radioactive isotopes have been used to determine the water/rock interaction processes involving 238U radioactive series, as well as to explain the origin of the dissolved 222Rn in groundwaters. The most important hydrogeochemical results obtained from groundwaters are: i) a large variety of hydrofacies is represented in them, corroborated by the cluster analysis; ii) they are not suitable for human consumption; iii) they have remained, apparently, over-saturated with respect to calcite and aragonite, and under-saturated with respect to gypsum, anhydrite and halite, over time; iv) they present theoretical temperatures in depth much higher than in the surface; v) they

  10. Evaluation of Tropical Transport in a Global Chemistry and Transport Model

    Science.gov (United States)

    Douglass, Anne R.; DaSilva, A. M.; Lin, S.-J.; Pawson, S.; Rood, R. B.; Bhartia, P. K. (Technical Monitor)

    2001-01-01

    Observations of constituents from satellite, aircraft and sondes can be utilized to develop diagnostics of various aspects of tropical transport. These include tropical mid-latitude isolation, the seasonal transport from the upper tropical troposphere to the mid-latitude lowermost stratosphere, the seasonal cycle of the tropical total ozone and its variability. These diagnostics will be applied to constituent fields from an off-line chemistry and transport model (CTM) driven by winds from two sources. These are the Finite Volume Community Climate Model (FV-CCM), a general circulation model that uses the NCAR CCM physics and the Lin and Rood dynamical core, and an assimilation system developed by the Data Assimilation Office at the Goddard Space Flight Center that uses the FV-CCM at its core. Signatures of the quasi-biennial oscillation present in the observations will be emphasized to understand differences between the two model transports and the transport inferred from the observations.

  11. Transportation of Dangerous Goods: Turkey Model

    Directory of Open Access Journals (Sweden)

    Murat Şencan

    2017-12-01

    Full Text Available The shortcomings in the implementation of hazardous substances transport in the world and in our country lead to very serious hazards. These problems lead to life, property and very serious environmental disasters. This is not only a matter of transportation, but also of the chemistry, textile and fuel industries. This study provides information on the legislation on dangerous goods transport in Turkey. It also contains technical information on hazardous substances, following the search of the relevant literature for the province of hazardous goods.

  12. Transport models for relativistic heavy-ion collisions at Relativistic ...

    Indian Academy of Sciences (India)

    Abstract. We review the transport models that are widely used to study the properties of the quark-gluon plasma formed in relativistic heavy-ion collisions at RHIC and LHC. We show that transport model analysis of two important and complementary observables, the anisotropic flow of bulk hadrons and suppression of ...

  13. Modeling of capacitated transportation systems for integral scheduling

    NARCIS (Netherlands)

    Ebben, Mark; van der Heijden, Matthijs C.; Hurink, Johann L.; Schutten, Johannes M.J.

    2003-01-01

    Motivated by a planned automated cargo transportation network, we consider transportation problems in which the finite capacity of resources has to be taken nto account. We present a flexible modeling methodology which allows to construct, evaluate, and improve feasible solutions. The modeling is

  14. Multimodal network models for robust transportation systems.

    Science.gov (United States)

    2009-10-01

    Since transportation infrastructure projects have a lifetime of many decades, project developers must consider : not only the current demand for the project but also the future demand. Future demand is of course uncertain and should : be treated as s...

  15. Advances in dynamic network modeling in complex transportation systems

    CERN Document Server

    Ukkusuri, Satish V

    2013-01-01

    This book focuses on the latest in dynamic network modeling, including route guidance and traffic control in transportation systems and other complex infrastructure networks. Covers dynamic traffic assignment, flow modeling, mobile sensor deployment and more.

  16. Symmetrization of mathematical model of charge transport in semiconductors

    Directory of Open Access Journals (Sweden)

    Alexander M. Blokhin

    2002-11-01

    Full Text Available A mathematical model of charge transport in semiconductors is considered. The model is a quasilinear system of differential equations. A problem of finding an additional entropy conservation law and system symmetrization are solved.

  17. Mode Choice Model for Public Transport with Categorized Latent Variables

    Directory of Open Access Journals (Sweden)

    Jian Chen

    2017-01-01

    Full Text Available Mode choice model for public transport, which integrates structural equation model (SEM and discrete choice model (DCM with categorized latent variables, was presented in this paper. Apart from identifying those important latent variables that affect mode choice for public transport, the objective of this study was also to develop an improved disaggregative model that better explains travel behavior of those decision-makers in choosing public transport. After extensive observations, selective latent variable sets which consist of latent variable components were chosen together with explicit variables in formulating the utility functions. Data collected in Chengdu city, China, were used to calibrate and validate the model. Results showed that the impact of fare on mode choice of public transport escalated in the SEM-DCM integrated model compared with the traditional logit model. The goodness of fit for the integrated model with latent variable sets is 0.201 higher than that of the traditional logit model, which proves that latent variables have an obvious impact on mode choice behavior, and the SEM-DCM integrated model has higher accuracy and stronger explanatory ability. The results are especially helpful for public transport operators to achieve higher mode share split by improving the service quality of public transport in terms of providing more convenience and better service environment for public transport users.

  18. A mesoscale chemical transport model (MEDIUM) nested in a global chemical transport model (MEDIANTE)

    Energy Technology Data Exchange (ETDEWEB)

    Claveau, J.; Ramaroson, R. [Office National d`Etudes et de Recherches Aerospatiales (ONERA), 92 - Chatillon (France)

    1997-12-31

    The lower stratosphere and upper troposphere (UT-LS) are frequently subject to mesoscale or local scale exchange of air masses occurring along discontinuities. This exchange (e.g. downward) can constitute one of the most important source of ozone from the stratosphere down to the middle troposphere where strong mixing dilutes the air mass and competing the non-linear chemistry. The distribution of the chemical species in the troposphere and the lower stratosphere depends upon various source emissions, e.g. from polluted boundary layer or from aircraft emissions. Global models, as well as chemical transport models describe the climatological state of the atmosphere and are not able to describe correctly the stratosphere and troposphere exchange. Mesoscale models go further in the description of smaller scales and can reasonably include a rather detailed chemistry. They can be used to assess the budget of NO{sub x} from aircraft emissions in a mesoscale domain. (author) 4 refs.

  19. Simulation Models in Testing Reliability of Transport Process

    Directory of Open Access Journals (Sweden)

    Jacyna Marianna

    2016-07-01

    Full Text Available The paper touches the problem of applying simulation models to assess the reliability of services in transport networks. Investigation of the transport processes in terms of their reliability is a complex decision-making task. The paper describes a method for assessing the reliability of transport process on the base of the criterion of minimizing the normalized lost time of vehicles. The time is wasted in a result of conflict situations occurring in the transport network during the transport process. The study includes stochastic distributions of system input. It enables studying the quality parameters of the transport network equipment, including service providers working under different workload and all kinds of disturbances. The method uses simulation models. Simulation studies were performed with Java Modelling Tools.

  20. One-Dimensional Transport with Equilibrium Chemistry (OTEQ) - A Reactive Transport Model for Streams and Rivers

    Science.gov (United States)

    Runkel, Robert L.

    2010-01-01

    OTEQ is a mathematical simulation model used to characterize the fate and transport of waterborne solutes in streams and rivers. The model is formed by coupling a solute transport model with a chemical equilibrium submodel. The solute transport model is based on OTIS, a model that considers the physical processes of advection, dispersion, lateral inflow, and transient storage. The equilibrium submodel is based on MINTEQ, a model that considers the speciation and complexation of aqueous species, acid-base reactions, precipitation/dissolution, and sorption. Within OTEQ, reactions in the water column may result in the formation of solid phases (precipitates and sorbed species) that are subject to downstream transport and settling processes. Solid phases on the streambed may also interact with the water column through dissolution and sorption/desorption reactions. Consideration of both mobile (waterborne) and immobile (streambed) solid phases requires a unique set of governing differential equations and solution techniques that are developed herein. The partial differential equations describing physical transport and the algebraic equations describing chemical equilibria are coupled using the sequential iteration approach. The model's ability to simulate pH, precipitation/dissolution, and pH-dependent sorption provides a means of evaluating the complex interactions between instream chemistry and hydrologic transport at the field scale. This report details the development and application of OTEQ. Sections of the report describe model theory, input/output specifications, model applications, and installation instructions. OTEQ may be obtained over the Internet at http://water.usgs.gov/software/OTEQ.

  1. Numerical modelling of multiphase flow and transport processes in landfills.

    Science.gov (United States)

    Kindlein, Jonatham; Dinkler, Dieter; Ahrens, Hermann

    2006-08-01

    Waste material in municipal landfills can be described as heterogeneous porous media, where flow and transport processes of gases and liquids are combined with local material degradation. This paper deals with the basic formulation of a multiphase flow and transport model applicable to the numerical analysis of coupled transport and reaction processes inside landfills. The transport model treats landfills within the framework of continuum mechanics, where flow and transport processes are described on a macroscopic level. The composition of organic and inorganic matter in the solid phase and its degradation are modelled on a microscopic scale. The degradation model captures the different reaction schemes of various microbial activities. Subsequently, transport and reaction processes have to be coupled, since emissions at the surface and from the drainage layer depend on the flow of leachate and gas, the transport of various substances and heat, and the biodegradation of organic matter. The theoretical considerations presented here are fundamental to the development of numerical models for the simulation of multiphase flow and transport processes inside landfills coupled with biochemical reactions and heat generation. The implicit modelling of leachate and gas flows including growth and decay of micro-organisms are innovative contributions to landfill modelling

  2. Sustainable intermodal freight transportation: Applying the geospatial intermodal freight transport model

    Science.gov (United States)

    Comer, Bryan

    To study the energy and environmental impacts of emissions associated with freight transportation, the Geospatial Intermodal Freight Transport (GIFT) model was created as a joint research collaborative between the Rochester Institute of Technology (RIT) and the University of Delaware (UD). The GIFT model is a Geographic Information Systems (GIS) based model that links the U.S. and Canadian water, rail, and road transportation networks through intermodal transfer facilities to create an intermodal network. The purpose of my thesis is to apply the GIFT model to examine potential public policies related to intermodal freight transportation in the Great Lakes region of the United States. My thesis will consist of two papers. The first paper will examine the environmental, economic, and time-of-delivery tradeoffs associated with freight transportation in the Great Lakes region and examine opportunities for marine vessels to replace a portion of heavy-duty trucks for containerized freight transport. The second paper will explore the potential benefits of using the Great Lakes as a corridor for short-sea shipping as part of a longer intermodal route. The intent of my thesis is to shed light on the current issues associated with freight transport in the Great Lakes region and present public policy alternatives to address said issues. Ideally, this thesis will better inform policymakers on the impacts and tradeoffs associated with freight transportation.

  3. Hydrogeochemical and isotopic characterization of Pesnica River, Slovenia

    Directory of Open Access Journals (Sweden)

    Tjaša Kanduč

    2016-12-01

    Full Text Available The surface water geochemistry and carbon cycling studied here depend mainly on geological composition of the river catchment. The investigated surface waters in the river Pesnica catchment that are heavily hydromorphologicaly altered (reservoirs, channelization, land melioration systems represent waters inflenced by chemical weathering of carbonates and of mostly clastic rocks (claystone, sandstones, marlstones and siltstones. The objectives of our study were to analyze hydrogeochemical and isotopic composition of dissolved (δ13CDIC and particulate carbon (δ13CPOC with characterization of suspended matter and evaluate biogeochemical processes in Pesnica River in Slovenia before and after the retention. Surface waters are generally close to saturation regarding calcite and dolomite, dissolved CO2 is 49 to 1000 times oversaturated relative to atmosphere. δ13C DIC was in the range from -14.8 to -4.2 ‰ and shows following biogeochemical processes in river system: degradation of organic matter, dissolution of carbonates and biological activity, which was confimed with SEM microscopy and EDXS microanalysis. Results of SEM/EDXS showed that suspended matter is composed of K, Mg and Ca from locations Pesnica 1 and Pesnica 2 (above retention Perniško lake. Sample from Pesnica 3 (below retention shows higher biological activity, while sample from Pesnica 4 (tributary of Pesnica, drainage channel Biš contains a lot of particles of microporous structure and fier structure, which are probably of anthropogenic origin. δ13CPOC is changing from -29.5 to-27.6‰ and showed different stages of degraded terrestrial material. More negative δ13CPOC are shown at location at drainage channel Biš and show higher terrestrial input in river system as locations 1, 2 and 3 Pesnica, which have higher δ13CPOC values. This fist results about suspended matter in Pesnica watershed serve for evaluation of anthropogenic inflences specially in relation with further

  4. Uranium Hydrogeochemical and Stream Sediment Reconnaissance in southwestern Montana

    Energy Technology Data Exchange (ETDEWEB)

    Broxton, D.E.

    1978-02-01

    The Los Alamos Scientific Laboratory conducted a Hydrogeochemical and Stream Sediment Reconnaissance in southwestern Montana from early August to mid-October of 1976. A total of 1240 water and 1933 sediment samples were collected from 1994 locations at a nominal density of one location per 10 km/sup 2/. The water samples were collected from streams, wells, and springs; sediment samples were taken at streams and springs. All samples were analyzed at Los Alamos for total uranium by fluorometry or delayed-neutron counting. The uranium content of water samples ranges from below the detection limit (less than 0.3 ppB) to 45.30 ppB and has a mean value of 1.40 ppB. The uranium content of the sediment samples ranges between 0.20 and 206.80 ppM and averages 6.12 ppM. The chosen uranium anomaly threshold value was 7 ppB for surface waters (streams), 9 ppB for groundwaters (wells and springs), and 25 ppM for all sediment samples. The study area consists of the following lithologic groups: Precambrian basement complex, Precambrian Belt metasediments, Paleozoic and Mesozoic shelf sediments, Cretaceous and early Tertiary volcanic and plutonic rocks, Laramide orogenic clastic sediments, and middle to late Tertiary volcanic rocks and intermontane basin sediments. Most of the anomalous water and sediment samples with well-developed dispersion trains occur in areas underlain by or adjacent to silicic plutonic rocks of the Idaho and Boulder batholiths. These anomalies may indicate the presence of uraniferous veins and pegmatites similar to those already known to exist in the area. Fewer anomalous water samples occur in areas underlain by Precambrian basement complex and Tertiary basin fill.

  5. Modeling atmospheric deposition using a stochastic transport model

    Energy Technology Data Exchange (ETDEWEB)

    Buckley, R.L.

    1999-12-17

    An advanced stochastic transport model has been modified to include the removal mechanisms of dry and wet deposition. Time-dependent wind and turbulence fields are generated with a prognostic mesoscale numerical model and are used to advect and disperse individually released particles that are each assigned a mass. These particles are subjected to mass reduction in two ways depending on their physical location. Particles near the surface experience a decrease in mass using the concept of a dry deposition velocity, while the mass of particles located within areas of precipitation are depleted using a scavenging coefficient. Two levels of complexity are incorporated into the particle model. The simple case assumes constant values of dry deposition velocity and scavenging coefficient, while the more complex case varies the values according to meteorology, surface conditions, release material, and precipitation intensity. Instantaneous and cumulative dry and wet deposition are determined from the mass loss due to these physical mechanisms. A useful means of validating the model results is with data available from a recent accidental release of Cesium-137 from a steel-processing furnace in Algeciras, Spain in May, 1998. This paper describes the deposition modeling technique, as well as a comparison of simulated concentration and deposition with measurements taken for the Algeciras release.

  6. Particle Tracking Model and Abstraction of Transport Processes

    Energy Technology Data Exchange (ETDEWEB)

    B. Robinson

    2000-04-07

    The purpose of the transport methodology and component analysis is to provide the numerical methods for simulating radionuclide transport and model setup for transport in the unsaturated zone (UZ) site-scale model. The particle-tracking method of simulating radionuclide transport is incorporated into the FEHM computer code and the resulting changes in the FEHM code are to be submitted to the software configuration management system. This Analysis and Model Report (AMR) outlines the assumptions, design, and testing of a model for calculating radionuclide transport in the unsaturated zone at Yucca Mountain. In addition, methods for determining colloid-facilitated transport parameters are outlined for use in the Total System Performance Assessment (TSPA) analyses. Concurrently, process-level flow model calculations are being carrier out in a PMR for the unsaturated zone. The computer code TOUGH2 is being used to generate three-dimensional, dual-permeability flow fields, that are supplied to the Performance Assessment group for subsequent transport simulations. These flow fields are converted to input files compatible with the FEHM code, which for this application simulates radionuclide transport using the particle-tracking algorithm outlined in this AMR. Therefore, this AMR establishes the numerical method and demonstrates the use of the model, but the specific breakthrough curves presented do not necessarily represent the behavior of the Yucca Mountain unsaturated zone.

  7. Transport services quality measurment using SERVQUAL model

    Directory of Open Access Journals (Sweden)

    Maksimović Mlađan V.

    2017-01-01

    Full Text Available Quality in the world is considered to be the most important phenomenon of our age, with a permanent and irreversible growing trend of its emphasis. Many companies have come to the conclusion that high quality of services can provide them with a potential competitive advantage, leading to superior sales results and profit making. The aim of this paper is to test the applicability of service SERVQUAL dimensions and measure the quality of services in the public transport of passengers. Based on the data obtained by researching the views of public transport users in Kragujevac using the SERVQUAL methodology and statistical analysis based on defined service quality dimensions, this research will show the level of quality of urban transport services in Kragujevac and based on this, make recommendations for improving the quality of service.

  8. Advanced transport systems analysis, modeling, and evaluation of performances

    CERN Document Server

    Janić, Milan

    2014-01-01

    This book provides a systematic analysis, modeling and evaluation of the performance of advanced transport systems. It offers an innovative approach by presenting a multidimensional examination of the performance of advanced transport systems and transport modes, useful for both theoretical and practical purposes. Advanced transport systems for the twenty-first century are characterized by the superiority of one or several of their infrastructural, technical/technological, operational, economic, environmental, social, and policy performances as compared to their conventional counterparts. The advanced transport systems considered include: Bus Rapid Transit (BRT) and Personal Rapid Transit (PRT) systems in urban area(s), electric and fuel cell passenger cars, high speed tilting trains, High Speed Rail (HSR), Trans Rapid Maglev (TRM), Evacuated Tube Transport system (ETT), advanced commercial subsonic and Supersonic Transport Aircraft (STA), conventionally- and Liquid Hydrogen (LH2)-fuelled commercial air trans...

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

    Directory of Open Access Journals (Sweden)

    Yangmin X. Kim

    2018-02-01

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

  10. Stochastic dynamics modeling solute transport in porous media modeling solute transport in porous media

    CERN Document Server

    Kulasiri, Don

    2002-01-01

    Most of the natural and biological phenomena such as solute transport in porous media exhibit variability which can not be modeled by using deterministic approaches. There is evidence in natural phenomena to suggest that some of the observations can not be explained by using the models which give deterministic solutions. Stochastic processes have a rich repository of objects which can be used to express the randomness inherent in the system and the evolution of the system over time. The attractiveness of the stochastic differential equations (SDE) and stochastic partial differential equations (SPDE) come from the fact that we can integrate the variability of the system along with the scientific knowledge pertaining to the system. One of the aims of this book is to explaim some useufl concepts in stochastic dynamics so that the scientists and engineers with a background in undergraduate differential calculus could appreciate the applicability and appropriateness of these developments in mathematics. The ideas ...

  11. Model for Estimation Urban Transportation Supply-Demand Ratio

    Directory of Open Access Journals (Sweden)

    Chaoqun Wu

    2015-01-01

    Full Text Available The paper establishes an estimation model of urban transportation supply-demand ratio (TSDR to quantitatively describe the conditions of an urban transport system and to support a theoretical basis for transport policy-making. This TSDR estimation model is supported by the system dynamic principle and the VENSIM (an application that simulates the real system. It was accomplished by long-term observation of eight cities’ transport conditions and by analyzing the estimated results of TSDR from fifteen sets of refined data. The estimated results indicate that an urban TSDR can be classified into four grades representing four transport conditions: “scarce supply,” “short supply,” “supply-demand balance,” and “excess supply.” These results imply that transport policies or measures can be quantified to facilitate the process of ordering and screening them.

  12. Strategic Network Modelling for Passenger Transport Pricing

    NARCIS (Netherlands)

    Smits, E.-S.

    2017-01-01

    In the last decade the Netherlands has experienced an economic recession. Now, in 2017, the economy is picking up again. This growth does not only come with advantages because economic growth demands more from the transport system. Congestion is increasing again, the capacity of the train system is

  13. Modelling anisotropic water transport in polymer composite ...

    Indian Academy of Sciences (India)

    Abstract. This work reports anisotropic water transport in a polymer composite consisting of an epoxy matrix reinforced with aligned triangular bars made of vinyl ester. By gravimetric experiments, water diffusion in resin and polymer composites were characterized. Parameters for Fickian diffusion and polymer relaxation ...

  14. Super parameterization of ocean dynamics for tracer transport models

    Science.gov (United States)

    Le Sommer, J.; Bricaud, C.; Madec, G.; Calone, C.; Chanut, J.; Ethe, C.; Perruche, C.

    2016-02-01

    Ocean mesoscale and submesoscale turbulence contribute to ocean tracer transport and to shaping ocean biogeochemical tracers distribution. Representing adequately tracer transport in ocean models therefore requires to increase model resolution so that the impact of ocean turbulence is adequately accounted for. But due to supercomputers power and storage limitations, global biogeochemical models are not yet run routinely at eddying resolution. Still, because the "effective resolution" of eddying ocean models is much coarser than the physical model grid resolution, tracer transport can be reconstructed to a large extent by computing tracer transport and diffusion with a model grid resolution close to the effective resolution of the physical model. This observation has motivated the implementation of a new capability in NEMO ocean model (http://www.nemo-ocean.eu/) that allows to run the physical model and the tracer transport model at different grid resolutions. Here, we present results obtained with this new capability applied to a synthetic age tracer in a global eddying model configuration. In this model configuration, ocean dynamic is computed at ¼° resolution but tracer transport is computed at 3/4° resolution. The solution obtained is compared to a reference setup, where age tracer is computed at the same grid resolution as ocean dynamics. We discuss possible options for defining the vertical diffusivity coefficient for the tracer transport model based on information from the high resolution grid. We describe the impact of this choice on the distribution and one the penetration of the age tracer. The method described here can found applications in ocean forecasting, such as the Copernicus Marine service operated by Mercator-Ocean, and in Earth System Models for climate applications.

  15. Finite difference methods for coupled flow interaction transport models

    Directory of Open Access Journals (Sweden)

    Shelly McGee

    2009-04-01

    Full Text Available Understanding chemical transport in blood flow involves coupling the chemical transport process with flow equations describing the blood and plasma in the membrane wall. In this work, we consider a coupled two-dimensional model with transient Navier-Stokes equation to model the blood flow in the vessel and Darcy's flow to model the plasma flow through the vessel wall. The advection-diffusion equation is coupled with the velocities from the flows in the vessel and wall, respectively to model the transport of the chemical. The coupled chemical transport equations are discretized by the finite difference method and the resulting system is solved using the additive Schwarz method. Development of the model and related analytical and numerical results are presented in this work.

  16. Keratin dynamics: modeling the interplay between turnover and transport.

    Science.gov (United States)

    Portet, Stéphanie; Madzvamuse, Anotida; Chung, Andy; Leube, Rudolf E; Windoffer, Reinhard

    2015-01-01

    Keratin are among the most abundant proteins in epithelial cells. Functions of the keratin network in cells are shaped by their dynamical organization. Using a collection of experimentally-driven mathematical models, different hypotheses for the turnover and transport of the keratin material in epithelial cells are tested. The interplay between turnover and transport and their effects on the keratin organization in cells are hence investigated by combining mathematical modeling and experimental data. Amongst the collection of mathematical models considered, a best model strongly supported by experimental data is identified. Fundamental to this approach is the fact that optimal parameter values associated with the best fit for each model are established. The best candidate among the best fits is characterized by the disassembly of the assembled keratin material in the perinuclear region and an active transport of the assembled keratin. Our study shows that an active transport of the assembled keratin is required to explain the experimentally observed keratin organization.

  17. Modelling travel time reliability in public transport route choice behaviour

    NARCIS (Netherlands)

    Swierstra, A.B.; van Nes, R.; Molin, E.J.E.

    2017-01-01

    The implementation of travel time reliability (TTR) in route choice behaviour is still not very common in transport models, especially not in a public transport context. The reasons probably are that it is difficult to measure and that there is no agreement how it best can be represented in

  18. A Coupled Model of Multiphase Flow, Reactive Biogeochemical Transport, Thermal Transport and Geo-Mechanics.

    Science.gov (United States)

    Tsai, C. H.; Yeh, G. T.

    2015-12-01

    In this investigation, a coupled model of multiphase flow, reactive biogeochemical transport, thermal transport and geo-mechanics in subsurface media is presented. It iteratively solves the mass conservation equation for fluid flow, thermal transport equation for temperature, reactive biogeochemical transport equations for concentration distributions, and solid momentum equation for displacement with successive linearization algorithm. With species-based equations of state, density of a phase in the system is obtained by summing up concentrations of all species. This circumvents the problem of having to use empirical functions. Moreover, reaction rates of all species are incorporated in mass conservation equation for fluid flow. Formation enthalpy of all species is included in the law of energy conservation as a source-sink term. Finite element methods are used to discretize the governing equations. Numerical experiments are presented to examine the accuracy and robustness of the proposed model. The results demonstrate the feasibility and capability of present model in subsurface media.

  19. Fractional diffusion models of transport in magnetically confined plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Castillo-Negrete, D. del; Carreras, B. A.; Lynch, V. E.

    2005-07-01

    Experimental and theoretical evidence suggests that transport in magnetically confined fusion plasmas deviates from the standard diffusion paradigm. Some examples include the confinement time scaling in L-mode plasmas, rapid pulse propagation phenomena, and inward transport in off-axis fueling experiments. The limitations of the diffusion paradigm can be traced back to the restrictive assumptions in which it is based. In particular, Fick's law, one of the cornerstones of diffusive transport, assumes that the fluxes only depend on local quantities, i. e. the spatial gradient of the field (s). another key issue is the Markovian assumption that neglects memory effects. Also, at a microscopic level, standard diffusion assumes and underlying Gaussian, uncorrelated stochastic process (i. e. a Brownian random walk) with well defined characteristic spatio-temporal scales. Motivated by the need to develop models of non-diffusive transport, we discuss here a class of transport models base on the use of fractional derivative operators. The models incorporates in a unified way non-Fickian transport, non-Markovian processes or memory effects, and non-diffusive scaling. At a microscopic level, the models describe an underlying stochastic process without characteristic spatio-temporal scales that generalizes the Brownian random walk. As a concrete case study to motivate and test the model, we consider transport of tracers in three-dimensional, pressure-gradient-driven turbulence. We show that in this system transport is non-diffusive and cannot be described in the context of the standard diffusion parading. In particular, the probability density function (pdf) of the radial displacements of tracers is strongly non-Gaussian with algebraic decaying tails, and the moments of the tracer displacements exhibit super-diffusive scaling. there is quantitative agreement between the turbulence transport calculations and the proposed fractional diffusion model. In particular, the model

  20. Hydrogeochemical investigation of six geothermal sites in Honduras, Central America

    Energy Technology Data Exchange (ETDEWEB)

    Goff, F.E.; Truesdell, A.H.; Grigsby, C.O.; Janik, C.J.; Shevenell, L.A.; Paredes, J.R.; Gutierrez, J.W.; Trujillo, Jr.; Counce, D.A.

    1987-06-01

    We conducted detailed hydrogeochemical investigations at six geothermal sites in western Honduras: Azacualpa, El Olivar, Pavana, Platanares, Sambo Creek, and San Ignacio. None of the sites is associated with Quaternary silicic volcanism, although El Olivar lies adjacent to a small Quaternary basalt field and Pavana is part of a belt of hot spring activity parallel to and 35 km east of the Central American volcanic arc. None of the sites contains acid-sulfate waters indicative of vapor-dominated conditions. Thermal fluids are characterized by pH between 7 and 10, Cl<125 mg/l, HCO/sub 3/>Cl, SO/sub 4/greater than or equal toCl, Bless than or equal to17 mg/l, Liless than or equal to4 mg/l, and Asless than or equal to1.25 mg/l. Stable isotope analyses of the water show that recharge to the geothermal systems generally occurs from areas of higher elevation adjacent to the sites. Tritium contents of apparently undiluted thermal fluids range from 0 to 0.4 T.U., indicating residence times of fluids in the systems of more than 500 y. Various geochemical indicators show that mixing of hot and cold end-member fluids occurs in the system at Platanares and, to a lesser degree, in the systems at San Ignacio and Azacualpa. No mixing is apparent in the fluids discharging at Pavana, Sambo Creek, or El Olivar. Boiling is the dominant process responsible for subtle geochemical variations at Azacualpa and, possibly, San Ignacio. Our best estimates of subsurface reservoir temperatures are 225/sup 0/C at Platanares, 190/sup 0/C at San Ignacio, 185/sup 0/C at Azacualpa, 155/sup 0/C at Sambo Creek, 150/sup 0/C at Pavana, and 120/sup 0/C at El Olivar. The estimated power output of the three hottest sites is 45 thermal megawatts at Platanares, 14 thermal megawatts at San Ignacio, and 13 thermal megawatts at Azacualpa.

  1. Metal transport across biomembranes: emerging models for a distinct chemistry.

    Science.gov (United States)

    Argüello, José M; Raimunda, Daniel; González-Guerrero, Manuel

    2012-04-20

    Transition metals are essential components of important biomolecules, and their homeostasis is central to many life processes. Transmembrane transporters are key elements controlling the distribution of metals in various compartments. However, due to their chemical properties, transition elements require transporters with different structural-functional characteristics from those of alkali and alkali earth ions. Emerging structural information and functional studies have revealed distinctive features of metal transport. Among these are the relevance of multifaceted events involving metal transfer among participating proteins, the importance of coordination geometry at transmembrane transport sites, and the presence of the largely irreversible steps associated with vectorial transport. Here, we discuss how these characteristics shape novel transition metal ion transport models.

  2. Modeling of pollutant emissions from road transport; Modelisation des emissions de polluants par le transport routier

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-07-01

    COPERT III (computer programme to calculate emissions from road transport) is the third version of an MS Windows software programme aiming at the calculation of air pollutant emissions from road transport. COPERT estimates emissions of all regulated air pollutants (CO, NO{sub x}, VOC, PM) produced by different vehicle categories as well as CO{sub 2} emissions on the basis of fuel consumption. This research seminar was organized by the French agency of environment and energy mastery (Ademe) around the following topics: the uncertainties and sensitiveness analysis of the COPERT III model, the presentation of case studies that use COPERT III for the estimation of road transport emissions, and the future of the modeling of road transport emissions: from COPERT III to ARTEMIS (assessment and reliability of transport emission models and inventory systems). This document is a compilation of 8 contributions to this seminar and dealing with: the uncertainty and sensitiveness analysis of the COPERT III model; the road mode emissions of the ESCOMPTE program: sensitivity study; the sensitivity analysis of the spatialized traffic at the time-aggregation level: application in the framework of the INTERREG project (Alsace); the road transport aspect of the regional air quality plan of Bourgogne region: exhaustive consideration of the road network; intercomparison of tools and methods for the inventory of emissions of road transport origin; evolution of the French park of vehicles by 2025: new projections; application of COPERT III to the French context: a new version of IMPACT-ADEME; the European ARTEMIS project: new structural considerations for the modeling of road transport emissions. (J.S.)

  3. Numerical Modelling on Fate and Transport of Petroleum ...

    Indian Academy of Sciences (India)

    21

    numerical model is developed to simulate the transport of benzene in an ..... unsaturated porous media (Richards 1931; van Genuchten 1980). ... conductivity for unsaturated soil such as Burdine (1953), Brooks and Corey (1964), Mualem.

  4. Strategic transportation model for oil in US waters

    Energy Technology Data Exchange (ETDEWEB)

    Lakovou, E.; Douligeris, C. [Miami Univ., FL (United States)

    1996-12-31

    This paper presents the development of a strategic transportation model for marine oil transportation in US waters. The model is a high-level strategic decision-making tool that will be used to interface with a risk analysis model, to identify ``weak`` links in the system and evaluate alternative routing and shipping scenarios. It may also be used to provide suggestions for the designation of lightering zones which will enable the U.S. to draw from the general world supply of tanker capacity and reduce oil transportation costs and risks. The model has been developed at the request of the United States Interagency Coordinating Committee for Oil Pollution Research to allow for the quantification of oil transported within the geographic boundaries of the United States, for the analysis of risks and effects of oil spills, and finally the identification of appropriate technologies that will support intervention and mitigation to reduce the impact of spills. (UK)

  5. Modeling of active transmembrane transport in a mixture theory framework.

    Science.gov (United States)

    Ateshian, Gerard A; Morrison, Barclay; Hung, Clark T

    2010-05-01

    This study formulates governing equations for active transport across semi-permeable membranes within the framework of the theory of mixtures. In mixture theory, which models the interactions of any number of fluid and solid constituents, a supply term appears in the conservation of linear momentum to describe momentum exchanges among the constituents. In past applications, this momentum supply was used to model frictional interactions only, thereby describing passive transport processes. In this study, it is shown that active transport processes, which impart momentum to solutes or solvent, may also be incorporated in this term. By projecting the equation of conservation of linear momentum along the normal to the membrane, a jump condition is formulated for the mechano-electrochemical potential of fluid constituents which is generally applicable to nonequilibrium processes involving active transport. The resulting relations are simple and easy to use, and address an important need in the membrane transport literature.

  6. Hydrogeochemical characteristics and assessment of water quality in the Al-Saad Lake, Abha Saudi Arabia

    Science.gov (United States)

    Mallick, Javed

    2017-10-01

    Hydrogeochemical characteristics and assessment of water quality investigations have been carried out at Abha, located in Saudi Arabia, where Al-Saad Lake represents a rare example of natural endorheic lake. The ecosystem within and around the Al-Saad Lake including catchment area is of great social, cultural, aesthetic, environmental and economic values to Abha. Sampling and experiments of lake water has been carried out with the aim of characterizing the main physico-chemical parameters, such as DO, EC, TDS, Mg2+, Ca2+, Na+, K+, SO4 2-, Cl-, HCO3, NO3 - and F- concentration. The ordinary kriging (OK) method was used to produce the spatial patterns of water quality. The Result of DO (mean 5.38 mg/L) trend in Al-Saad Lake is not very encouraging as majority of the lake area is under DO stress or marginally above it. So, proper management strategies are needed to be formulated to protect flora and fauna of the lake. Furthermore, the chemical analysis results show the abundance of the major cations in the order Mg2+ > Ca2+ > Na+ > K+ whereas the abundance of anions are in the order SO4 2- > Cl- > HCO3 > NO3 - > F-. The result obtained in this investigation inferred that the cations in water i.e. sodium and iron are within the permissible limits but magnesium and potassium have exceeded the permissible limit. Whereas anions such as nitrate and fluoride are within the permissible range but chloride and sulphate have exceeded the permissible limits. The concentration of cation, magnesium (Mg) and potassium (K) in the lake water has exceeded the desirable range (30, 10 mg/L, respectively). This may be due to weathering and transported from rocks and particularly from sulphate deposits such as gypsum and anhydride and subsequently ends up in water. The concentration of anion, Sulphate (SO4) and chloride are above the desirable limit. The major source of bicarbonate are the carbonate rocks containing calcite (CaCO3) and dolomite (CaMg (CO3)2), Calcium (Ca) and Magnesium

  7. Multicomponent Reactive Transport Modeling in Aquifers

    Science.gov (United States)

    Blanco, C. A.; Barajas, D. A.; Donado, L. D.

    2008-12-01

    This work presents a methodology for calculating reaction rates in a reactive transport system under kinetic and equilibrium conditions for a bidimensional fully saturated homogeneous aquifer [GRDMOMAS,2006]. The system considered is the scenario of precipitation/dissolution of two minerals [Donado et al, In preparation] B4(s) and B5(s) in the presence of three aqueous species, B1, B2 and B3, governed by the reactions B1+B2⇌ B4(s) [1] B1+B3⇌ B5(s) [2] Reaction ([1]) is considered to occur in instantaneous equilibrium, while reaction ([2]) is considered to be a slow (i.e., kinetic) reaction [Cirpka and Valocchi, 2007]. Using the approach proposed by Molins et al. [Water Resour. Res., 40(10), W10301, doi:10.1029/2003WR002970, 2004], two linear combinations of the concentrations of the reacting species, known as the conservative and kinetic components u and uk, are defined in order to decouple the equilibrium reaction from the kinetic one. This way the set of equations which describes the reactive transport system is reduced to two partial differential equations; the first one of them is a second-order linear homogeneous parabolic partial differential equation solely in terms of the conservative component u, which can be solved separately, while the second one is a second-order non-linear non-homogeneous parabolic partial differential equation in terms of both the conservative and kinetic components. An approximate numerical solution of the aforementioned partial differential equations is obtained by applying a mixed solution by means of the finite elements method for flow and finite differences method for transport. A bilinear grid is used for discretizing the flow-reaction domain while the Crank-Nicholson implicit scheme is used for the temporal integration of the equations. The nonlinearity of the second partial differential equation is treated using a predictor-corrector algorithm. The behaviour of the reactive transport system is evaluated in term of two of

  8. Modelling of hydrodynamics and mecury transport in lake Velenje. Part 2, Modelling and model verification

    OpenAIRE

    Kotnik, Jože; Žagar, Dušan; Rajar, Rudi; Horvat, Milena

    2004-01-01

    PCFLOW3D - a three-dimensional mathematical model that was developed at the Chair of Fluid Mechanics of the Faculty of Civil and Geodetic Engineering, University of Ljubljana, was used for hydrodynamic and Hg transport simulations in Lake Velenje. The model is fully non-linear and computes three velocity components, water elevation and pressure. Transport-dispersion equations for salinity and heat (and/or any pollutant) are further used to compute the distributions of these par...

  9. The thermoballistic transport model a novel approach to charge carrier transport in semiconductors

    CERN Document Server

    Lipperheide, Reinhard

    2014-01-01

    The book presents a comprehensive survey of the thermoballistic approach to charge carrier transport in semiconductors. This semi-classical approach, which the authors have developed over the past decade, bridges the gap between the opposing drift-diffusion and ballistic  models of carrier transport. While incorporating basic features of the latter two models, the physical concept underlying the thermoballistic approach constitutes a novel, unifying scheme. It is based on the introduction of "ballistic configurations" arising from a random partitioning of the length of a semiconducting sample into ballistic transport intervals. Stochastic averaging of the ballistic carrier currents over the ballistic configurations results in a position-dependent thermoballistic current, which is the key element of the thermoballistic concept and forms  the point of departure for the calculation of all relevant transport properties. In the book, the thermoballistic concept and its implementation are developed in great detai...

  10. Object-oriented data model of the municipal transportation

    Science.gov (United States)

    Pan, Yuqing; Sheng, Yehua; Zhang, Guiying

    2008-10-01

    The transportation problem is always one of main questions each big city all over the world faces. Managing the municipal transportation using GIS is becoming the important trend. And the data model is the transportation information system foundation. The organization and storage of the data must consider well in the system design. The data model not only needs to meet the demand that the transportation navigates, but also needs to achieve the good visual effects, also can carry on the management and the maintenance to the traffic information. According to the object-oriented theory and the method, the road is divided into segment, intersection. This paper analyzed the driveway, marking, sign and other transportation facilities and the relationship with the segment, intersection and constructed the municipal transportation data model which is adequate to the demand of vehicles navigation, visual and management. The paper also schemes the the all kinds of transportation data. The practice proves that this data model can satisfy the application demands of traffic management system.

  11. Transport of bacteria in aquifer sediment: experiments and modeling

    Science.gov (United States)

    Ding, Dong

    2010-05-01

    A mathematical model based on the advection-dispersion equation, modified to account for growth, decay, attachment, and detachment of microorganisms, was developed to describe the transport and growth of bacteria in aquifers. Column experiments on the transport of a species of sulfate-reducing bacteria through saturated-aquifer sediment were conducted to gain a quantitative knowledge of the attachment and detachment processes. Relevant parameter values such as the attachment-site capacity of the sediment and the attachment and detachment coefficients under different conditions, were obtained by fitting the experimental data with the non-growth condition transport model. The transport model was then refined and improved to incorporate the microbial sulfate reduction mechanism. To evaluate the applicability of this model, bacterial transport in aquifers under both nutrient-rich and oligotrophic environments was modeled by employing the parameters gained from experiments and from available literature; the model results were consistent with observations reported in former studies. In addition, the results revealed that the distribution of bacteria in the aqueous phase and in the sediments is directly related to the attachment-site capacity of the sediment. Thus, the attachment-site capacity of the sediment is a key factor to evaluate the transport and growth of bacteria in aquifers.

  12. Hydrogeochemical characterization and Natural Background Levels in urbanized areas: Milan Metropolitan area (Northern Italy)

    Science.gov (United States)

    De Caro, Mattia; Crosta, Giovanni B.; Frattini, Paolo

    2017-04-01

    Although aquifers in densely populated and industrialized areas are extremely valuable and sensitive to contamination, an estimate of the groundwater quality status relative to baseline conditions is lacking for many of them. This paper provides a hydrogeochemical characterization of the groundwater in the Milan metropolitan area, one of the most densely populated areas in Europe. First, a conceptual model of the study area based on the analysis of the spatial distribution of natural chemical species and indicator contaminants is presented. The hydrochemical facies of the study area depend on the lithology of catchments drained by the main contributing rivers and on the aquifer settings. The anthropogenic influence on the groundwater quality of superficial aquifers is studied by means of probability plots, concentration versus depth plots and spatial-temporal plots for nitrate, sulfate and chloride. These allow differentiation of contaminated superficial aquifers from deep confined aquifers with baseline water quality. Natural Background Levels (NBL) of selected species (Cl, Na, NH4, SO4, NO3, As, Fe, Mn and Zn) are estimated by means of the pre-selection (PS) and the component separation (CS) statistical approaches. The NBLs depend on hydrogeological settings of the study area; sodium, chloride, sulfate and zinc NBL values never exceed the environmental water quality standards. NBL values of ammonium, iron, arsenic and manganese exceed the environmental water quality standards in the anaerobic portion of the aquifers. On the basis of observations, a set of criteria and precautions are suggested for adoption with both PS and CS methods in the aquifer characterization of highly urbanized areas.

  13. ATTILA - Atmospheric Tracer Transport In a Langrangian Model

    Energy Technology Data Exchange (ETDEWEB)

    Reithmeier, C.; Sausen, R.

    2000-07-01

    The Lagrangian model ATTILA (atmospheric tracer transport in a Lagrangian model) has been developed to treat the global-scale transport of passive trace species in the atmosphere within the framework of a general circulation model (GCM). ATTILA runs online within the GCM ECHAM4 and uses the GCM produced wind field to advect the centrois of 80.000 to 180.000 constant mass air parcels into which the model atmosphere is divided. Each trace constituent is thereby represented by a mass mixing ratio in each parcel. ATTILA contains state-of-the-art parameterizations of convection, turbulent boundary layer mixing, and interparcel transport and provides an algorithm to map the tracer concentrations from the trajectories to the ECHAM model grid. We use two experiments to evaluate the transport characteristics of ATTILA against observations and the standard semiLagrangian transport scheme of ECHAM. In the first experiment we simulate the distribution of the short-lived tracer Radon ({sup 222}Rn) in order to examine fast vertical transport over continents, and long-range transport from the continents to remote areas. In the second experiment, we simulate the distribution of radiocarbon ({sup 14}C) that was injected into the northern stratosphere during the nuclear weapon tests in the early 60ties, in order to examine upper tropospheric and stratospheric transport characteristics. ATTILA compares well to the observations and in many respects to the semiLagrangian scheme. However, contrary to the semiLagrangian scheme, ATTILA shows a greatly reduced meridional transport in the upper troposphere and lower stratosphere, and a reduced downward flux from the stratosphere to the troposphere, especially in midlatitudes. Since both transport schemes use the same model meteorology, we conclude that the often cited enhanced meridional transport and overestimated downward flux in ECHAM as described above is rather due to the numerical properties of the semiLagrangian scheme than due to an

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

    Directory of Open Access Journals (Sweden)

    Martin Gregory T

    2004-11-01

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

  15. Collisional broadening of angular correlations in a multiphase transport model

    Science.gov (United States)

    Edmonds, Terrence; Li, Qingfeng; Wang, Fuqiang

    2017-10-01

    Systematic comparisons of jetlike correlation data to radiative and collisional energy loss model calculations are essential to extract transport properties of the quark-gluon medium created in relativistic heavy ion collisions. This paper presents a transport study of collisional broadening of jetlike correlations, by following parton-parton collision history in a multiphase transport (AMPT) model. The correlation shape is studied as functions of the number of parton-parton collisions suffered by a high transverse momentum probe parton (Ncoll) and the azimuth of the probe relative to the reaction plane (ϕfin.probe). Correlation is found to broaden with increasing Ncoll and ϕfin.probe from in- to out-of-plane direction. This study provides a transport model reference for future jet-medium interaction studies.

  16. Model prodrugs for the intestinal oligopeptide transporter

    DEFF Research Database (Denmark)

    Nielsen, C U; Andersen, R; Brodin, Birger

    2001-01-01

    (sigma*) may influence the acid, water or base catalyzed model drug release rates, when released from series of D-Glu-Ala and D-Asp-Ala pro-moieties. Release rates were investigated in both aqueous solutions with varying pH, ionic strength, and buffer concentrations as well as in in vitro biological...... media. The release rates of all the investigated model drug molecules followed first-order kinetics and were dependent on buffer concentration, pH, ionic strength, and model drug electronegativity. The electronegativity of the model drug influenced acid, water and base catalyzed release from D...

  17. Analysis of a deep well recharge experiment by calibrating a reactive transport model with field data

    Science.gov (United States)

    Saaltink, Maarten W.; Ayora, Carlos; Stuyfzand, Pieter J.; Timmer, Harrie

    2003-08-01

    This paper describes the modeling of the hydrogeochemical effects of deep well recharge of oxic water into an anoxic pyrite-bearing aquifer. Kinetic expressions have been used for mineral dissolution-precipitation rates and organic matter oxidation. Hydrological and chemical parameters of the model were calibrated to field measurements. The results showed that oxidation of pyrite (FeS 2) and, to a lesser extent, organic matter dominate the changes in quality of the recharged water during its passage through the aquifer. The recharge leads to the consumption of oxygen and nitrate and the formation of sulfate and ferrihydrite. Complexation reactions, cation exchange and precipitation and dissolution of calcite, siderite and rhodochrosite were also identified through the modeling. Despite problems of non-uniqueness of the calibrated parameters, the model was used successfully to depict the geochemical processes occurring in the aquifer. Non-uniqueness can be avoided by constraining the model as much as possible to measurements and/or data from literature, although they cannot be considered always as fixed values and should be considered as stochastic variables instead.

  18. Mathematical Model of Ion Transport in Electrodialysis Process

    Directory of Open Access Journals (Sweden)

    F.S. Rohman

    2010-10-01

    Full Text Available Mathematical models of ion transport in electrodialysis process is reviewed and their basics concept is discussed. Three scales of ion transport reviewed are: 1 ion transport in the membrane, where two approaches are used, the irreversible thermodynamics and modeling of the membrane material; 2 ion transport in a three-layer system composed of a membrane with two adjoining diffusion layers; and 3 coupling with hydraulic flow system in an electrodialysis 2D and 3D cell, where the differential equation of convectivediffusion is used. Most of the work carried out in the past implemented NP equations since relatively easily coupled with other equations describing hydrodynamic conditions and ion transport in the surrounding solutions, chemical reactions in the solutions and the membrane, boundary and other conditions. However, it is limited to point ionic transport in homogenous and uniformly - grainy phases of structure. © 2008 BCREC UNDIP. All rights reserved.[Received: 21 January 2008, Accepted: 10 March 2008][How to Cite: F.S. Rohman, N. Aziz (2008. Mathematical Model of Ion Transport in Electrodialysis Process. Bulletin of Chemical Reaction Engineering and Catalysis, 3(1-3: 3-8. doi:10.9767/bcrec.3.1-3.7122.3-8][How to Link/DOI: http://dx.doi.org/10.9767/bcrec.3.1-3.7122.3-8 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/7122 ] 

  19. Mathematical Model of Ion Transport in Electrodialysis Process

    Directory of Open Access Journals (Sweden)

    F. S. Rohman

    2008-04-01

    Full Text Available Mathematical models of ion transport in electrodialysis process is reviewed and their basics concept is discussed.Three scales of ion transport reviewed are: 1 ion transport in the membrane, where two approachesare used, the irreversible thermodynamics and modeling of the membrane material; 2 ion transport in athree-layer system composed of a membrane with two adjoining diffusion layers; and 3 coupling with hydraulicflow system in an electrodialysis 2D and 3D cell, where the differential equation of convectivediffusionis used. Most of the work carried out in the past implemented NP equations since relatively easilycoupled with other equations describing hydrodynamic conditions and ion transport in the surrounding solutions,chemical reactions in the solutions and the membrane, boundary and other conditions. However, itis limited to point ionic transport in homogenous and uniformly - grainy phases of structure.© 2008 BCREC UNDIP. All rights reserved.[Received: 21 January 2008, Accepted: 10 March 2008][How to Cite: F.S. Rohman, N. Aziz (2008. Mathematical Model of Ion Transport in Electrodialysis Process. Bulletin of Chemical Reaction Engineering and Catalysis, 3(1-3: 3-8. doi:10.9767/bcrec.3.1-3.16.3-8

  20. Numerical modelling of cuttings transport with foam in inclined wells

    Energy Technology Data Exchange (ETDEWEB)

    Osunde, O.; Kuru, E. [Alberta Univ., Edmonton, AB (Canada)

    2006-07-01

    A one dimensional transient state mechanistic model of cuttings transport with foam in inclined wells was developed and solved numerically to predict the optimum foam flow rate (liquid and gas rate) and rheological properties that would maximize cuttings transport efficiency in inclined well. The model was then verified using experimental results obtained by Capo110. A literature review focusing on the mechanism of cuttings transport in wells, foam drilling with a focus on the foam rheology, foam flow and cutting transport with foam was presented. The new model consisted of a detailed sensitivity analysis of the effect of gas and liquid flowing rates, drilling rate, foam rheological properties, borehole geometry, wellbore inclination and the rate of gas and liquid influx from the reservoir on the cutting transport efficiency in inclined wells. One of the conclusions from the study was that the gas injection rate has a significant effect on the cuttings transport process, with a more pronounced effect at lower gas injection rates. The liquid injection rate has little effect on the cuttings transport process with negligible effect at very low or very high gas injection rate. 110 refs., 3 tabs., 16 figs.

  1. UNCERTAINTY SUPPLY CHAIN MODEL AND TRANSPORT IN ITS DEPLOYMENTS

    Directory of Open Access Journals (Sweden)

    Fabiana Lucena Oliveira

    2014-05-01

    Full Text Available This article discusses the Model Uncertainty of Supply Chain, and proposes a matrix with their transportation modes best suited to their chains. From the detailed analysis of the matrix of uncertainty, it is suggested transportation modes best suited to the management of these chains, so that transport is the most appropriate optimization of the gains previously proposed by the original model, particularly when supply chains are distant from suppliers of raw materials and / or supplies.Here we analyze in detail Agile Supply Chains, which is a result of Uncertainty Supply Chain Model, with special attention to Manaus Industrial Center. This research was done at Manaus Industrial Pole, which is a model of industrial agglomerations, based in Manaus, State of Amazonas (Brazil, which contemplates different supply chains and strategies sharing same infrastructure of transport, handling and storage and clearance process and uses inbound for suppliers of raw material.  The state of art contemplates supply chain management, uncertainty supply chain model, agile supply chains, Manaus Industrial Center (MIC and Brazilian legislation, as a business case, and presents concepts and features, of each one. The main goal is to present and discuss how transport is able to support Uncertainty Supply Chain Model, in order to complete management model. The results obtained confirms the hypothesis of integrated logistics processes are able to guarantee attractivity for industrial agglomerations, and open discussions when the suppliers are far from the manufacturer center, in a logistics management.

  2. Transportation Sector Model of the National Energy Modeling System. Volume 2 -- Appendices: Part 1

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-01-01

    This volume contains input data and parameters used in the model of the transportation sector of the National Energy Modeling System. The list of Transportation Sector Model variables includes parameters for the following: Light duty vehicle modules (fuel economy, regional sales, alternative fuel vehicles); Light duty vehicle stock modules; Light duty vehicle fleet module; Air travel module (demand model and fleet efficiency model); Freight transport module; Miscellaneous energy demand module; and Transportation emissions module. Also included in these appendices are: Light duty vehicle market classes; Maximum light duty vehicle market penetration parameters; Aircraft fleet efficiency model adjustment factors; and List of expected aircraft technology improvements.

  3. Analysis regarding the transport network models. Case study on finding the optimal transport route

    Science.gov (United States)

    Stîngă, V.-G.

    2017-08-01

    Transport networks are studied most of the time from a graph theory perspective, mostly studied in a static way, in order to emphasize their characteristics like: topology, morphology, costs, traffic flows etc. There are many methods used to describe these characteristics at local and global level. Usually when analysing the transport network models, the aim is to achieve minimum capacity transit or minimum cost of operating or investment. Throughout this paper we will get an insight into the many models of the transport network that were presented over the years and we will try to make a short analysis regarding the most important ones. We will make a case study on finding the optimal route by using one of the models presented within this paper.

  4. Computer modeling of electron and proton transport in chloroplasts.

    Science.gov (United States)

    Tikhonov, Alexander N; Vershubskii, Alexey V

    2014-07-01

    Photosynthesis is one of the most important biological processes in biosphere, which provides production of organic substances from atmospheric CO2 and water at expense of solar energy. In this review, we contemplate computer models of oxygenic photosynthesis in the context of feedback regulation of photosynthetic electron transport in chloroplasts, the energy-transducing organelles of the plant cell. We start with a brief overview of electron and proton transport processes in chloroplasts coupled to ATP synthesis and consider basic regulatory mechanisms of oxygenic photosynthesis. General approaches to computer simulation of photosynthetic processes are considered, including the random walk models of plastoquinone diffusion in thylakoid membranes and deterministic approach to modeling electron transport in chloroplasts based on the mass action law. Then we focus on a kinetic model of oxygenic photosynthesis that includes key stages of the linear electron transport, alternative pathways of electron transfer around photosystem I (PSI), transmembrane proton transport and ATP synthesis in chloroplasts. This model includes different regulatory processes: pH-dependent control of the intersystem electron transport, down-regulation of photosystem II (PSII) activity (non-photochemical quenching), the light-induced activation of the Bassham-Benson-Calvin (BBC) cycle. The model correctly describes pH-dependent feedback control of electron transport in chloroplasts and adequately reproduces a variety of experimental data on induction events observed under different experimental conditions in intact chloroplasts (variations of CO2 and O2 concentrations in atmosphere), including a complex kinetics of P700 (primary electron donor in PSI) photooxidation, CO2 consumption in the BBC cycle, and photorespiration. Finally, we describe diffusion-controlled photosynthetic processes in chloroplasts within the framework of the model that takes into account complex architecture of

  5. Cosmic-Ray Transport in Heliospheric Magnetic Structures. II. Modeling Particle Transport through Corotating Interaction Regions

    Energy Technology Data Exchange (ETDEWEB)

    Kopp, Andreas [Université Libre de Bruxelles, Service de Physique Statistique et des Plasmas, CP 231, B-1050 Brussels (Belgium); Wiengarten, Tobias; Fichtner, Horst [Institut für Theoretische Physik IV, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Effenberger, Frederic [Department of Physics and KIPAC, Stanford University, Stanford, CA 94305 (United States); Kühl, Patrick; Heber, Bernd [Institut für Experimentelle und Angewandte Physik, Christian-Albrecht-Universität zu Kiel, D-24098 Kiel (Germany); Raath, Jan-Louis; Potgieter, Marius S. [Centre for Space Research, North-West University, 2520 Potchefstroom (South Africa)

    2017-03-01

    The transport of cosmic rays (CRs) in the heliosphere is determined by the properties of the solar wind plasma. The heliospheric plasma environment has been probed by spacecraft for decades and provides a unique opportunity for testing transport theories. Of particular interest for the three-dimensional (3D) heliospheric CR transport are structures such as corotating interaction regions (CIRs), which, due to the enhancement of the magnetic field strength and magnetic fluctuations within and due to the associated shocks as well as stream interfaces, do influence the CR diffusion and drift. In a three-fold series of papers, we investigate these effects by modeling inner-heliospheric solar wind conditions with the numerical magnetohydrodynamic (MHD) framework Cronos (Wiengarten et al., referred as Paper I), and the results serve as input to a transport code employing a stochastic differential equation approach (this paper). While, in Paper I, we presented results from 3D simulations with Cronos, the MHD output is now taken as an input to the CR transport modeling. We discuss the diffusion and drift behavior of Galactic cosmic rays using the example of different theories, and study the effects of CIRs on these transport processes. In particular, we point out the wide range of possible particle fluxes at a given point in space resulting from these different theories. The restriction of this variety by fitting the numerical results to spacecraft data will be the subject of the third paper of this series.

  6. Examining an important urban transportation management tool: subarea modeling

    Directory of Open Access Journals (Sweden)

    Xueming CHEN

    2009-12-01

    Full Text Available At present, customized subarea models have been widely used in local transportation planning throughout the United States. The biggest strengths of a subarea model lie in its more detailed and accurate modeling outputs which better meet local planning requirements. In addition, a subarea model can substantially reduce database size and model running time. In spite of these advantages, subarea models remain quite weak in maintaining consistency with a regional model, modeling transit projects, smart growth measures, air quality conformity, and other areas. Both opportunities and threats exist for subarea modeling. In addition to examining subarea models, this paper introduces the decision-making process in choosing a proper subarea modeling approach (windowing versus focusing and software package. This study concludes that subarea modeling will become more popular in the future. More GIS applications, travel surveys, transit modeling, microsimulation software utilization, and other modeling improvements are expected to be incorporated into the subarea modeling process.

  7. Multiscale modeling of fluid transport in tumors.

    Science.gov (United States)

    Chapman, S Jonathan; Shipley, Rebecca J; Jawad, Rossa

    2008-11-01

    A model for fluid flow through the leaky neovasculature and porous interstitium of a solid tumor is developed. A network of isolated capillaries is analyzed in the limit of small capillary radius, and analytical expressions for the hydraulic conductivities and fractional leakage coefficients derived. This model is then homogenized to give a continuum description in terms of the vascular density. The resulting equations comprise a double porous medium with coupled Darcy flow through the interstitium and vasculature.

  8. Stencil method: a Markov model for transport in porous media

    Science.gov (United States)

    Delgoshaie, A. H.; Tchelepi, H.; Jenny, P.

    2016-12-01

    In porous media the transport of fluid is dominated by flow-field heterogeneity resulting from the underlying transmissibility field. Since the transmissibility is highly uncertain, many realizations of a geological model are used to describe the statistics of the transport phenomena in a Monte Carlo framework. One possible way to avoid the high computational cost of physics-based Monte Carlo simulations is to model the velocity field as a Markov process and use Markov Chain Monte Carlo. In previous works multiple Markov models for discrete velocity processes have been proposed. These models can be divided into two general classes of Markov models in time and Markov models in space. Both of these choices have been shown to be effective to some extent. However some studies have suggested that the Markov property cannot be confirmed for a temporal Markov process; Therefore there is not a consensus about the validity and value of Markov models in time. Moreover, previous spacial Markov models have only been used for modeling transport on structured networks and can not be readily applied to model transport in unstructured networks. In this work we propose a novel approach for constructing a Markov model in time (stencil method) for a discrete velocity process. The results form the stencil method are compared to previously proposed spacial Markov models for structured networks. The stencil method is also applied to unstructured networks and can successfully describe the dispersion of particles in this setting. Our conclusion is that both temporal Markov models and spacial Markov models for discrete velocity processes can be valid for a range of model parameters. Moreover, we show that the stencil model can be more efficient in many practical settings and is suited to model dispersion both on structured and unstructured networks.

  9. Biophysical Modeling of Cross-Shore Plankton Transport

    Science.gov (United States)

    Fujimura, A.; Reniers, A.; Paris, C. B.; Shanks, A.; MacMahan, J.; Morgan, S.

    2016-02-01

    Coastal ecosystems are influenced by cross-shore flows. Processes that create coastal plankton distributions are not well understood, even though possible mechanisms of plankton transport in the surf zone have been investigated. Our data from a rip-channeled beach show that concentrations of zooplankton and phytoplankton are higher in the surf zone than offshore. To examine how plankton are transported toward the shore, we used a coupled biophysical model, comprised of Delft3D wave/flow simulations and an individual-based model for tracking plankton. Model results indicate that onshore delivery of zooplankton is enhanced by Stokes drift, wave-driven bottom boundary streaming, alongshore topographic variability, and turbulence-dependent sinking behavior of zooplankton. Phytoplankton sinking may also be accelerated by turbulence, but the mechanism differs from that which affects zooplankton. Turbulence has the potential to increase phytoplankton growth rates. Therefore, the phytoplankton transport model includes turbulence-induced sinking velocity and growth rate, although the latter appears to have little influence on phytoplankton distributions. Modeled phytoplankton concentrations in the surf zone are much lower than expected, although the zooplankton transport model qualitatively reproduced our observations. Thus, there must be other possible factors influencing phytoplankton transport, some of which will be discussed.

  10. Aeolian Sediment Transport Integration in General Stratigraphic Forward Modeling

    Directory of Open Access Journals (Sweden)

    T. Salles

    2011-01-01

    Full Text Available A large number of numerical models have been developed to simulate the physical processes involved in saltation, and, recently to investigate the interaction between soil vegetation cover and aeolian transport. These models are generally constrained to saltation of monodisperse particles while natural saltation occurs over mixed soils. We present a three-dimensional numerical model of steady-state saltation that can simulate aeolian erosion, transport and deposition for unvegetated mixed soils. Our model simulates the motion of saltating particles using a cellular automata algorithm. A simple set of rules is used and takes into account an erosion formula, a transport model, a wind exposition function, and an avalanching process. The model is coupled to the stratigraphic forward model Sedsim that accounts for a larger number of geological processes. The numerical model predicts a wide range of typical dune shapes, which have qualitative correspondence to real systems. The model reproduces the internal structure and composition of the resulting aeolian deposits. It shows the complex formation of dune systems with cross-bedding strata development, bounding surfaces overlaid by fine sediment and inverse grading deposits. We aim to use it to simulate the complex interactions between different sediment transport processes and their resulting geological morphologies.

  11. The Colombian Strategic Freight Transport Model Based on Product Analysis

    Directory of Open Access Journals (Sweden)

    Victor Cantillo

    2014-12-01

    Full Text Available Freight transport modelling at interregional scale is relevant for planning issues. However, freight modelling processes are complex because it is not easy to define the relevant variables in the analysis, and to obtain the required information on freight movements through the network. These facts raise the need to adapt the modelling framework to each context.This paper proposes a strategic national freight transport modelling framework developed as a variant of the traditional four-step modelling process with additional steps to estimate traffic flows from freight flows and to consider empty trips. The country of Colombia is used as the case study to implement and calibrate the proposed model. The data, data sources, and modelling methodologies used for each step are explained. In addition, data limitations and measures taken to complement the available data are discussed. From the implementation, the authors identify a set of advantages derived from the modelling approaches considered and suggestions for improvement.

  12. Hydrogeochemical and Isotopic Indicators of Hydraulic Fracturing Flowback Fluids in Shallow Groundwater and Stream Water, derived from Dameigou Shale Gas Extraction in the Northern Qaidam Basin.

    Science.gov (United States)

    Zheng, Zhaoxian; Zhang, Hongda; Chen, Zongyu; Li, Xufeng; Zhu, Pucheng; Cui, Xiaoshun

    2017-06-06

    Most of the shale gas production in northwest China is from continental shale. Identifying hydrogeochemical and isotopic indicators of toxic hydraulic fracturing flowback fluids (HFFF) has great significance in assessing the safety of drinking water from shallow groundwater and streamwater. Hydrogeochemical and isotopic data for HFFF from the Dameigou shale formations (Cl/Br ratio (1.81 × 10-4-6.52 × 10-4), Ba/Sr (>0.2), δ11B (-10-1‰), and εSWSr (56-65, where εSWSr is the deviation of the 87Sr/86Sr ratio from that of seawater in parts per 104)) were distinct from data for the background saline shallow groundwater and streamwater before fracturing. Mixing models indicated that inorganic elemental signatures (Br/Cl, Ba/Sr) and isotopic fingerprints (δ11B, εSWSr) can be used to distinguish between HFFF and conventional oil-field brine in shallow groundwater and streamwater. These diagnostic indicators were applied to identify potential releases of HFFF into shallow groundwater and streamwater during fracturing, flowback and storage. The monitored time series data for shallow groundwater and streamwater exhibit no clear trends along mixing curves toward the HFFF end member, indicating that there is no detectable release occurring at present.

  13. Sustainable logistics and transportation optimization models and algorithms

    CERN Document Server

    Gakis, Konstantinos; Pardalos, Panos

    2017-01-01

    Focused on the logistics and transportation operations within a supply chain, this book brings together the latest models, algorithms, and optimization possibilities. Logistics and transportation problems are examined within a sustainability perspective to offer a comprehensive assessment of environmental, social, ethical, and economic performance measures. Featured models, techniques, and algorithms may be used to construct policies on alternative transportation modes and technologies, green logistics, and incentives by the incorporation of environmental, economic, and social measures. Researchers, professionals, and graduate students in urban regional planning, logistics, transport systems, optimization, supply chain management, business administration, information science, mathematics, and industrial and systems engineering will find the real life and interdisciplinary issues presented in this book informative and useful.

  14. Evaluation of cloud convection and tracer transport in a three-dimensional chemical transport model

    Directory of Open Access Journals (Sweden)

    W. Feng

    2011-06-01

    Full Text Available We investigate the performance of cloud convection and tracer transport in a global off-line 3-D chemical transport model. Various model simulations are performed using different meteorological (reanalyses (ERA-40, ECMWF operational and ECMWF Interim to diagnose the updraft mass flux, convective precipitation and cloud top height.

    The diagnosed upward mass flux distribution from TOMCAT agrees quite well with the ECMWF reanalysis data (ERA-40 and ERA-Interim below 200 hPa. Inclusion of midlevel convection improves the agreement at mid-high latitudes. However, the reanalyses show strong convective transport up to 100 hPa, well into the tropical tropopause layer (TTL, which is not captured by TOMCAT. Similarly, the model captures the spatial and seasonal variation of convective cloud top height although the mean modelled value is about 2 km lower than observed.

    The ERA-Interim reanalyses have smaller archived upward convective mass fluxes than ERA-40, and smaller convective precipitation, which is in better agreement with satellite-based data. TOMCAT captures these relative differences when diagnosing convection from the large-scale fields. The model also shows differences in diagnosed convection with the version of the operational analyses used, which cautions against using results of the model from one specific time period as a general evaluation.

    We have tested the effect of resolution on the diagnosed modelled convection with simulations ranging from 5.6° × 5.6° to 1° × 1°. Overall, in the off-line model, the higher model resolution gives stronger vertical tracer transport, however, it does not make a large change to the diagnosed convective updraft mass flux (i.e., the model results using the convection scheme fail to capture the strong convection transport up to 100 hPa as seen in the archived convective mass fluxes. Similarly, the resolution of the forcing winds in the higher resolution CTM does not make a

  15. Transport modeling of sorbing tracers in artificial fractures

    Energy Technology Data Exchange (ETDEWEB)

    Keum, Dong Kwon; Baik, Min Hoon; Park, Chung Kyun; Cho, Young Hwan; Hahn, Phil Soo

    1998-02-01

    This study was performed as part of a fifty-man year attachment program between AECL (Atomic Energy Canada Limited) and KAERI. Three kinds of computer code, HDD, POMKAP and VAMKAP, were developed to predict transport of contaminants in fractured rock. MDDM was to calculate the mass transport of contaminants in a single fracture using a simple hydrodynamic dispersion diffusion model. POMKAP was to predict the mass transport of contaminants by a two-dimensional variable aperture model. In parallel with modeling, the validation of models was also performed through the analysis of the migration experimental data obtained in acrylic plastic and granite artificial fracture system at the Whiteshell laboratories, AECL, Canada. (author). 34 refs., 11 tabs., 76 figs.

  16. Modelling of human transplacental transport as performed in Copenhagen, Denmark

    DEFF Research Database (Denmark)

    Mathiesen, Line; Mørck, Thit Aarøe; Zuri, Giuseppina

    2014-01-01

    Placenta perfusion models are very effective when studying the placental mechanisms in order to extrapolate to real-life situations. The models are most often used to investigate the transport of substances between mother and foetus, including the potential metabolism of these. We have studied...... the relationships between maternal and foetal exposures to various compounds including pollutants such as polychlorinated biphenyls, polybrominated flame retardants, nanoparticles as well as recombinant human antibodies. The compounds have been studied in the human placenta perfusion model and to some extent...... in vitro with an established human monolayer trophoblast cell culture model. Results from our studies distinguish placental transport of substances by physicochemical properties, adsorption to placental tissue, binding to transport and receptor proteins and metabolism. We have collected data from different...

  17. Numerical modelling of cuttings transport with foam in vertical wells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Y.; Kuru, E. [University of Alberta, Edmonton, AB (Canada)

    2005-03-01

    Development of a one-dimensional unsteady-state mathematical model is described. The model was developed to simulate the transport of cuttings with foam in vertical wells. Numerical solution was used to predict average cuttings concentration in the well as a function of the drilling rate, the gas and the liquid injection rates, the rate of gas and liquid influx from the reservoir, and the borehole geometry. The effects of key drilling parameters on the efficiency of cuttings transport with foam in vertical wells was determined by sensitivity analyses. Verification of model predictions and the results of the sensitivity analyses are presented. The model is claimed to be useful in writing computer programs for design purposes to determine optimal volumetric gas/liquid flow rates, injection pressure and back pressure required to drill vertical wells. It can also be used to develop guidelines for use in operational control of cutting transport with foam. 37 refs., 2 tabs., 13 figs.

  18. GIS model to evaluate the accessibility to major transport ways

    Directory of Open Access Journals (Sweden)

    Antonio Tache

    2015-03-01

    Full Text Available In order to ensure a balanced accessibility to major transport ways, supporting spatial development and economic growth, a GIS model to assess accessibility it was proposed. The model is measuring the average cost of travel (by car, usually from a point to a predetermined number of destinations measured in units of time (minutes. Using the ARCGIS Spatial Analyst module, accessibility territorial indicators were calculated and presented as cartograms and maps that are outlining the accessibility to major transportation routes and to major cities. The proposed model to assess accessibility was tested for Tulcea county (NUTS III level and for the South East region (NUTS II level.

  19. Radiative Transport Modelling of Thermal Barrier Coatings

    Science.gov (United States)

    2017-03-24

    Figure 1. Schematic of multiple scatter events inside a TBC D l1 l2 l3 l4l5 5 Two random walk simulation codes were adapted and improved upon, one...one particular n = 2 scatter event. l1 lb 1 2 l2 db DISTRIBUTION A. Approved for public release: distribution unlimited. 11 The solution to Eq. (13...development of the new model (Task 2) and in testing it (Task 3). Some model parameter definitions are shown in Figure 1. The scattering medium is

  20. On the Economic Order Quantity Model With Transportation Costs

    NARCIS (Netherlands)

    S.I. Birbil (Ilker); K. Bulbul; J.B.G. Frenk (Hans); H.M. Mulder (Martyn)

    2009-01-01

    textabstractWe consider an economic order quantity type model with unit out-of-pocket holding costs, unit opportunity costs of holding, fixed ordering costs and general transportation costs. For these models, we analyze the associated optimization problem and derive an easy procedure for determining

  1. A transport model for prediction of wildfire behavior

    Energy Technology Data Exchange (ETDEWEB)

    Linn, R.R.

    1997-07-01

    Wildfires are a threat to human life and property, yet they are an unavoidable part of nature. In the past people have tried to predict wildfire behavior through the use of point functional models but have been unsuccessful at adequately predicting the gross behavior of the broad spectrum of fires that occur in nature. The majority of previous models do not have self-determining propagation rates. The author uses a transport approach to represent this complicated problem and produce a model that utilizes a self-determining propagation rate. The transport approach allows one to represent a large number of environments including transition regions such as those with nonhomogeneous vegetation and terrain. Some of the most difficult features to treat are the imperfectly known boundary conditions and the fine scale structure that is unresolvable, such as the specific location of the fuel or the precise incoming winds. The author accounts for the microscopic details of a fire with macroscopic resolution by dividing quantities into mean and fluctuating parts similar to what is done in traditional turbulence modelling. The author develops a complicated model that includes the transport of multiple gas species, such as oxygen and volatile hydrocarbons, and tracks the depletion of various fuels and other stationary solids and liquids. From this model the author also forms a simplified local burning model with which he performs a number of simulations for the purpose of demonstrating the properties of a self-determining transport-based wildfire model.

  2. Spatial Economics Model Predicting Transport Volume

    Directory of Open Access Journals (Sweden)

    Lu Bo

    2016-10-01

    Full Text Available It is extremely important to predict the logistics requirements in a scientific and rational way. However, in recent years, the improvement effect on the prediction method is not very significant and the traditional statistical prediction method has the defects of low precision and poor interpretation of the prediction model, which cannot only guarantee the generalization ability of the prediction model theoretically, but also cannot explain the models effectively. Therefore, in combination with the theories of the spatial economics, industrial economics, and neo-classical economics, taking city of Zhuanghe as the research object, the study identifies the leading industry that can produce a large number of cargoes, and further predicts the static logistics generation of the Zhuanghe and hinterlands. By integrating various factors that can affect the regional logistics requirements, this study established a logistics requirements potential model from the aspect of spatial economic principles, and expanded the way of logistics requirements prediction from the single statistical principles to an new area of special and regional economics.

  3. THE BIPOLARON MODEL IN TRANSPORT PROPERTIES OF ...

    African Journals Online (AJOL)

    D. Mani Kongnine

    un composé ferromagnétique, le Pr2Co7 , est faite. 2. MODELE DU BIPOLARON. Plusieurs modèles théoriques expliquent la non linéarité de la résistivité parmi lesquels celui du bipolaron. D'après ce modèle, les bipolarons ...

  4. Modeling bacterial transport in the subsurface using HP1

    Science.gov (United States)

    Zhang, H.; Olson, M. S.

    2011-12-01

    Bacterial infiltration through the subsurface has been studied experimentally under different conditions of interest and is dependent on a variety of physical, chemical and biological factors, such as solution chemistry, bacterial size and surface properties, and mineral surfaces etc. However, most bacterial transport studies are often not directly relevant to processes occurring in natural systems. Bacteria have been frequently detected and reported in stormwater runoff. Mixing of stormwater runoff with groundwater in the subsurface during infiltration causes changes in solution chemistry, which lead to changes in bacterial surface properties (such as zeta potential) and collector surface charge and properties. This study focuses on bacterial transport as stormwater runoff infiltrates into the subsurface. A microbial reactive transport model is developed using HP1(HYDRUS1D-PHREEQC), which accounts for changes in the physical and chemical factors that control bacterial attachment onto liquid-solid and liquid-air interfaces. Bacterial attachment efficiency to liquid-solid interfaces is considered both under unfavorable conditions, as predicted by DLVO theory and the Maxwell approach coupling both primary and secondary-minima deposition, and under favorable conditions. Bacterial attachment at the liquid-air interface is modeled using mass transfer equations, which vary with changes in the water content profile. Different scenarios are simulated to observe bacterial transport behavior in uniformly and variably unsaturated soil, under high and low surface ponding depths and with varied and constant rates of bacterial attachment. Column transport experiments have been developed to experimentally validate the microbial reactive transport model.

  5. 3D data model of transportation network in city

    Science.gov (United States)

    Zuo, Xiao-qing; Li, Qing-quan; Yang, Bi-sheng

    2005-10-01

    Modern data-capture technology, especially digital photogrammetry technology, provides abundant data resources for digital city. Transportation network, forming framework of city, is an important component of city and a vital fundamental data of ITS and LBS (Location-based Services). Therefore, developing a data model is very valuable and significant which can describe 3D feature of city road network and support 3D navigation. Nowadays existing 3D GIS data models pay less attention to the support of transportation application, such as 3D vehicle navigation and traffic simulation, and previous GIS for transportation (GIS-T) data models failed to support 3D visualization. In view of it, we developed a 3D data model for transportation network that (1) supports of linear referencing system (LRS) and dynamic segmentation, (2) makes network topology build on the basis of 3D geometry network, and (3) realizes the transformation between linear coordinate and spatial coordinate. A performance study depicts that the proposed model can not only realize 3D visualization but also have transportation analysis (such 3D Vehicle navigation) more efficiently and conveniently.

  6. Assessment of parametric uncertainty for groundwater reactive transport modeling,

    Science.gov (United States)

    Shi, Xiaoqing; Ye, Ming; Curtis, Gary P.; Miller, Geoffery L.; Meyer, Philip D.; Kohler, Matthias; Yabusaki, Steve; Wu, Jichun

    2014-01-01

    The validity of using Gaussian assumptions for model residuals in uncertainty quantification of a groundwater reactive transport model was evaluated in this study. Least squares regression methods explicitly assume Gaussian residuals, and the assumption leads to Gaussian likelihood functions, model parameters, and model predictions. While the Bayesian methods do not explicitly require the Gaussian assumption, Gaussian residuals are widely used. This paper shows that the residuals of the reactive transport model are non-Gaussian, heteroscedastic, and correlated in time; characterizing them requires using a generalized likelihood function such as the formal generalized likelihood function developed by Schoups and Vrugt (2010). For the surface complexation model considered in this study for simulating uranium reactive transport in groundwater, parametric uncertainty is quantified using the least squares regression methods and Bayesian methods with both Gaussian and formal generalized likelihood functions. While the least squares methods and Bayesian methods with Gaussian likelihood function produce similar Gaussian parameter distributions, the parameter distributions of Bayesian uncertainty quantification using the formal generalized likelihood function are non-Gaussian. In addition, predictive performance of formal generalized likelihood function is superior to that of least squares regression and Bayesian methods with Gaussian likelihood function. The Bayesian uncertainty quantification is conducted using the differential evolution adaptive metropolis (DREAM(zs)) algorithm; as a Markov chain Monte Carlo (MCMC) method, it is a robust tool for quantifying uncertainty in groundwater reactive transport models. For the surface complexation model, the regression-based local sensitivity analysis and Morris- and DREAM(ZS)-based global sensitivity analysis yield almost identical ranking of parameter importance. The uncertainty analysis may help select appropriate likelihood

  7. Observed and Modeled Sediment Transport Around Katama Inlet, Martha's Vineyard

    Science.gov (United States)

    Hopkins, J.; Elgar, S.; Raubenheimer, B.

    2014-12-01

    Katama Inlet, connecting Katama Bay to the Atlantic Ocean on the southern shoreline of Martha's Vineyard, MA, has migrated eastward more than 2.5 km since it was breached during the Patriot's Day storm in 2007. This morphological evolution, typical of the inlet's decadal cycle of breach-migration-closure, is owing to sediment transport driven by wave-orbital velocities, breaking-wave-generated mean currents, and tidal flows. Here, the rapidly evolving shoreline near Katama Inlet and on the southern edge of Martha's Vineyard is investigated using field observations and numerical model simulations. The bathymetry was surveyed in summer 2013 and 2014, and tides, waves, and currents were measured for a month in August 2013 and 2014 in the surf zone (~2 m water depth), on the outer edge of the ebb shoal offshore of the inlet mouth (~6 m depth), and on the inner continental shelf (~7 m depth). The model [Delft3D with coupled waves (SWAN) and currents] skillfully simulates observed wave heights, wave directions, and tidal currents, and is used here to estimate sediment transport rates. Model results suggest that during the relatively calm August conditions there is little transport on the inner shelf, but there is significant transport that changes directions with the tide on the outer ebb shoal. Transport rates in the surf zone decrease and become more unidirectional (wave-driven) with distance away (west) from the mouth of the inlet. In August, transport of suspended sediments is relatively more important on the outer ebb shoal than near the surf zone, where bedload transport dominates. The relative impact of these types of simulated transport on the migration of Katama Inlet will be discussed. Funded by ONR, ASD(R&E), NSF, and NDSEG.

  8. Computer-Supported Modelling of Multi modal Transportation Networks Rationalization

    Directory of Open Access Journals (Sweden)

    Ratko Zelenika

    2007-09-01

    Full Text Available This paper deals with issues of shaping and functioning ofcomputer programs in the modelling and solving of multimoda Itransportation network problems. A methodology of an integrateduse of a programming language for mathematical modellingis defined, as well as spreadsheets for the solving of complexmultimodal transportation network problems. The papercontains a comparison of the partial and integral methods ofsolving multimodal transportation networks. The basic hypothesisset forth in this paper is that the integral method results inbetter multimodal transportation network rationalization effects,whereas a multimodal transportation network modelbased on the integral method, once built, can be used as the basisfor all kinds of transportation problems within multimodaltransport. As opposed to linear transport problems, multimodaltransport network can assume very complex shapes. This papercontains a comparison of the partial and integral approach totransp01tation network solving. In the partial approach, astraightforward model of a transp01tation network, which canbe solved through the use of the Solver computer tool within theExcel spreadsheet inteiface, is quite sufficient. In the solving ofa multimodal transportation problem through the integralmethod, it is necessmy to apply sophisticated mathematicalmodelling programming languages which supp01t the use ofcomplex matrix functions and the processing of a vast amountof variables and limitations. The LINGO programming languageis more abstract than the Excel spreadsheet, and it requiresa certain programming knowledge. The definition andpresentation of a problem logic within Excel, in a manner whichis acceptable to computer software, is an ideal basis for modellingin the LINGO programming language, as well as a fasterand more effective implementation of the mathematical model.This paper provides proof for the fact that it is more rational tosolve the problem of multimodal transportation networks by

  9. GIS-Based Analytical Tools for Transport Planning: Spatial Regression Models for Transportation Demand Forecast

    Directory of Open Access Journals (Sweden)

    Simone Becker Lopes

    2014-04-01

    Full Text Available Considering the importance of spatial issues in transport planning, the main objective of this study was to analyze the results obtained from different approaches of spatial regression models. In the case of spatial autocorrelation, spatial dependence patterns should be incorporated in the models, since that dependence may affect the predictive power of these models. The results obtained with the spatial regression models were also compared with the results of a multiple linear regression model that is typically used in trips generation estimations. The findings support the hypothesis that the inclusion of spatial effects in regression models is important, since the best results were obtained with alternative models (spatial regression models or the ones with spatial variables included. This was observed in a case study carried out in the city of Porto Alegre, in the state of Rio Grande do Sul, Brazil, in the stages of specification and calibration of the models, with two distinct datasets.

  10. Catalog of selected heavy duty transport energy management models

    Science.gov (United States)

    Colello, R. G.; Boghani, A. B.; Gardella, N. C.; Gott, P. G.; Lee, W. D.; Pollak, E. C.; Teagan, W. P.; Thomas, R. G.; Snyder, C. M.; Wilson, R. P., Jr.

    1983-01-01

    A catalog of energy management models for heavy duty transport systems powered by diesel engines is presented. The catalog results from a literature survey, supplemented by telephone interviews and mailed questionnaires to discover the major computer models currently used in the transportation industry in the following categories: heavy duty transport systems, which consist of highway (vehicle simulation), marine (ship simulation), rail (locomotive simulation), and pipeline (pumping station simulation); and heavy duty diesel engines, which involve models that match the intake/exhaust system to the engine, fuel efficiency, emissions, combustion chamber shape, fuel injection system, heat transfer, intake/exhaust system, operating performance, and waste heat utilization devices, i.e., turbocharger, bottoming cycle.

  11. Modeling transport and deposition of the Mekong River sediment

    Science.gov (United States)

    Xue, Zuo; He, Ruoying; Liu, J. Paul; Warner, John C.

    2012-01-01

    A Coupled Wave–Ocean–SedimentTransport Model was used to hindcast coastal circulation and fine sedimenttransport on the Mekong shelf in southeastern Asian in 2005. Comparisons with limited observations showed that the model simulation captured the regional patterns and temporal variability of surface wave, sea level, and suspended sediment concentration reasonably well. Significant seasonality in sedimenttransport was revealed. In summer, a large amount of fluvial sediments was delivered and deposited near the MekongRiver mouth. In the following winter, strong ocean mixing, and coastal current lead to resuspension and southwestward dispersal of a small fraction of previously deposited sediments. Model sensitivity experiments (with reduced physics) were performed to investigate the impact of tides, waves, and remotely forced ambient currents on the transport and dispersal of the fluvial sediment. Strong wave mixing and downwelling-favorable coastal current associated with the more energetic northeast monsoon in the winter season are the main factors controlling the southwestward along-shelf transport.

  12. Physics models in the toroidal transport code PROCTR

    Energy Technology Data Exchange (ETDEWEB)

    Howe, H.C.

    1990-08-01

    The physics models that are contained in the toroidal transport code PROCTR are described in detail. Time- and space-dependent models are included for the plasma hydrogenic-ion, helium, and impurity densities, the electron and ion temperatures, the toroidal rotation velocity, and the toroidal current profile. Time- and depth-dependent models for the trapped and mobile hydrogenic particle concentrations in the wall and a time-dependent point model for the number of particles in the limiter are also included. Time-dependent models for neutral particle transport, neutral beam deposition and thermalization, fusion heating, impurity radiation, pellet injection, and the radial electric potential are included and recalculated periodically as the time-dependent models evolve. The plasma solution is obtained either in simple flux coordinates, where the radial shift of each elliptical, toroidal flux surface is included to maintain an approximate pressure equilibrium, or in general three-dimensional torsatron coordinates represented by series of helical harmonics. The detailed coupling of the plasma, scrape-off layer, limiter, and wall models through the neutral transport model makes PROCTR especially suited for modeling of recycling and particle control in toroidal plasmas. The model may also be used in a steady-state profile analysis mode for studying energy and particle balances starting with measured plasma profiles.

  13. Multiscale modeling for fluid transport in nanosystems.

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jonathan W.; Jones, Reese E.; Mandadapu, Kranthi Kiran; Templeton, Jeremy Alan; Zimmerman, Jonathan A.

    2013-09-01

    Atomistic-scale behavior drives performance in many micro- and nano-fluidic systems, such as mircrofludic mixers and electrical energy storage devices. Bringing this information into the traditionally continuum models used for engineering analysis has proved challenging. This work describes one such approach to address this issue by developing atomistic-to-continuum multi scale and multi physics methods to enable molecular dynamics (MD) representations of atoms to incorporated into continuum simulations. Coupling is achieved by imposing constraints based on fluxes of conserved quantities between the two regions described by one of these models. The impact of electric fields and surface charges are also critical, hence, methodologies to extend finite-element (FE) MD electric field solvers have been derived to account for these effects. Finally, the continuum description can have inconsistencies with the coarse-grained MD dynamics, so FE equations based on MD statistics were derived to facilitate the multi scale coupling. Examples are shown relevant to nanofluidic systems, such as pore flow, Couette flow, and electric double layer.

  14. Microbial diversity and hydrogeochemical characteristics of natural CO2-rich springs in Korea

    Science.gov (United States)

    Ko, D.; Do, H. K.; Yun, S. T.; Chung, H.

    2016-12-01

    Natural CO2-rich springs are unique ecosystems where microbial communities are adapted to extreme conditions including low pH. We analyzed bacterial and archaeal community composition and hydrogeochemical features in two different natural CO2-rich springs located in the south-eastern part of Korea. Analyses of hydrogeochemical characteristics and 16S rRNA gene pyrosequencing of bacteria and archaea showed remarkable distinction between the two CO2-rich springs, Hansil (HS) and Chosukol (CS). Both springs were weakly acidic (pH 5.1 to 6.2), but the electrical conductivity and the concentration of major ions such as Ca2+, Mg2+, Na+, K+, Fe+ and HCO3- were significantly higher in HS spring than in CS spring. Among the bacterial communities, the family of Gallionellaceae (ferro-oxidant), a member of the order Gallionellales was predominant in HS spring, occupying 72% of the total abundance. On the other hand, in CS spring, Oxalobacteraceae (chemolithotrophs) and Comamonadaceae (chemoorganotrophs), the families of the order Burkholderiales were predominant and their relative abundance was 65 and 21%, respectively. Among the archaeal communities, the phylum Thaumarchaeota was predominant in CS spring, its relative abundance being 72%. In HS spring, the phyla Thaumarchaeota, Euryarchaeota and Crenarchaeota were relatively evenly distributed. Our results suggest that the significant differences in bacterial and archaeal communities of each CO2-rich spring are closely related to hydrogeochemical characteristics, and also those were in accordance with the geological formation process of CO2-rich springs.

  15. The Extended Generalized Cost Concept and its Application in Freight Transport and General Equilibrium Modeling

    NARCIS (Netherlands)

    Tavasszy, L.; Davydenko, I.; Ruijgrok, K.

    2009-01-01

    The integration of Spatial Equilibrium models and Freight transport network models is important to produce consistent scenarios for future freight transport demand. At various spatial scales, we see the changes in production, trade, logistics networking and transportation, being driven by

  16. Radon transport in fractured soil. Laboratory experiments and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Hoff, A.

    1997-10-01

    Radon (Rn-222) transport in fractured soil has been investigated by laboratory experiments and by modelling. Radon transport experiments have been performed with two sand columns (homogeneous and inhomogeneous) and one undisturbed clayey till column containing a net of preferential flow paths (root holes). A numerical model (the finite-element model FRACTRAN) and an analytic model (a pinhole model) have been applied in simulations if soil gas and radon transport in fractured soil. Experiments and model calculations are included in a discussion of radon entry rates into houses placed on fractured soil. The main conclusion is, that fractures does not in general alter transport of internally generated radon out of soil, when the pressure and flow conditions in the soil is comparable to the conditions prevailing under a house. This indicates the important result, that fractures in soil have no impact on radon entry into a house beyond that of an increased gas permeability, but a more thorough investigation of this subject is needed. Only in the case where the soil is exposed to large pressure gradients, relative to gradients induced by a house, may it be possible to observe effects of radon exchange between fractures and matrix. (au) 52 tabs., 60 ill., 5 refs.

  17. A coupled energy transport and hydrological model for urban canopies

    Science.gov (United States)

    Wang, Z.; Bou-Zeid, E.; Smith, J. A.

    2011-12-01

    Urban land-atmosphere interaction has been attracting more research efforts in order to understand the complex physics of flow and mass and heat transport in urban surfaces and the lower urban atmosphere. In this work, we developed and implemented a new physically-based single-layer urban canopy model, coupling the surface exchange of energy and the subsurface transport of water/soil moisture. The new model incorporates sub-facet heterogeneity for each urban surface (roof, wall or ground). This better simulates the energy transport in urban canopy layers, especially over low-intensity built (suburban type) terrains that include a significant fraction of vegetated surfaces. We implemented detailed urban hydrological models for both natural terrains (bare soil and vegetation) and porous engineered materials with water-holding capacity (concrete, gravel, etc). The skill of the new scheme was tested against experimental data collected through a wireless sensor network deployed over the campus of Princeton University. The model performance was found to be robust and insensitive to changes in weather conditions or seasonal variability. Predictions of the volumetric soil water content were also in good agreement with field measurements, highlighting the model capability of capturing subsurface water transport for urban lawns. The new model was also applied to a case study assessing different strategies, i.e. white versus green roofs, in the mitigation of urban heat island effect.

  18. A transport model for computer simulation of wildfires

    Energy Technology Data Exchange (ETDEWEB)

    Linn, R. [Los Alamos National Lab., NM (United States)

    1997-12-31

    Realistic self-determining simulation of wildfires is a difficult task because of a large variety of important length scales (including scales on the size of twigs or grass and the size of large trees), imperfect data, complex fluid mechanics and heat transfer, and very complicated chemical reactions. The author uses a transport approach to produce a model that exhibits a self-determining propagation rate. The transport approach allows him to represent a large number of environments such as those with nonhomogeneous vegetation and terrain. He accounts for the microscopic details of a fire with macroscopic resolution by dividing quantities into mean and fluctuating parts similar to what is done in traditional turbulence modeling. These divided quantities include fuel, wind, gas concentrations, and temperature. Reaction rates are limited by the mixing process and not the chemical kinetics. The author has developed a model that includes the transport of multiple gas species, such as oxygen and volatile hydrocarbons, and tracks the depletion of various fuels and other stationary solids and liquids. From this model he develops a simplified local burning model with which he performs a number of simulations that demonstrate that he is able to capture the important physics with the transport approach. With this simplified model he is able to pick up the essence of wildfire propagation, including such features as acceleration when transitioning to upsloping terrain, deceleration of fire fronts when they reach downslopes, and crowning in the presence of high winds.

  19. Consistency between 2D-3D Sediment Transport models

    Science.gov (United States)

    Villaret, Catherine; Jodeau, Magali

    2017-04-01

    Sediment transport models have been developed and applied by the engineering community to estimate transport rates and morphodynamic bed evolutions in river flows, coastal and estuarine conditions. Environmental modelling systems like the open-source Telemac modelling system include a hierarchy of models from 1D (Mascaret), 2D (Telemac-2D/Sisyphe) and 3D (Telemac-3D/Sedi-3D) and include a wide range of processes to represent sediment flow interactions under more and more complex situations (cohesive, non-cohesive and mixed sediment). Despite some tremendous progresses in the numerical techniques and computing resources, the quality/accuracy of model results mainly depend on the numerous choices and skills of the modeler. In complex situations involving stratification effects, complex geometry, recirculating flows… 2D model assumptions are no longer valid. A full 3D turbulent flow model is then required in order to capture the vertical mixing processes and to represent accurately the coupled flow/sediment distribution. However a number of theoretical and numerical difficulties arise when dealing with sediment transport modelling in 3D which will be high-lighted : (1) Dependency of model results to the vertical grid refinement and choice of boundary conditions and numerical scheme (2) The choice of turbulence model determines also the sediment vertical distribution which is governed by a balance between the downward settling term and upward turbulent diffusion. (3) The use of different numerical schemes for both hydrodynamics (mean and turbulent flow) and sediment transport modelling can lead to some inconsistency including a mismatch in the definition of numerical cells and definition of boundary conditions. We discuss here those present issues and present some detailed comparison between 2D and 3D simulations on a set of validation test cases which are available in the Telemac 7.2 release using both cohesive and non-cohesive sediments.

  20. Computer-based modelling and optimization in transportation

    CERN Document Server

    Rossi, Riccardo

    2014-01-01

    This volume brings together works resulting from research carried out by members of the EURO Working Group on Transportation (EWGT) and presented during meetings and workshops organized by the Group under the patronage of the Association of European Operational Research Societies in 2012 and 2013. The main targets of the EWGT include providing a forum to share research information and experience, encouraging joint research and the development of both theoretical methods and applications, and promoting cooperation among the many institutions and organizations which are leaders at national level in the field of transportation and logistics. The primary fields of interest concern operational research methods, mathematical models and computation algorithms, to solve and sustain solutions to problems mainly faced by public administrations, city authorities, public transport companies, service providers and logistic operators. Related areas of interest are: land use and transportation planning, traffic control and ...

  1. Transport of bacteria in porous media: II. A model for convective Transport and growth.

    Science.gov (United States)

    Sarkar, A K; Georgiou, G; Sharma, M M

    1994-08-05

    A model is presented for the coupled processes of bacterial growth and convective transport of bacteria has been modeled using a fractional flow approach. The various mechanisms of bacteria retention can be incorporated into the model through selection of an appropriate shape of the fractional flow curve. Permeability reduction due to pore plugging by bacteria was simulated using the effective medium theory. In porous media, the rates of transport and growth of bacteria, the generation of metabolic products, and the consumption of nutrients are strongly coupled processes. Consequently, the set of governing conservation equations form a set of coupled, nonlinear partial differential equations that were solved numerically. Reasonably good agreement between the model and experimental data has been obtained indicating that the physical processes incorporated in the model are adequate. The model has been used to predict the in situ transport and growth of bacteria, nutrient consumption, and metabolite production. It can be particularly useful in simulating laboratory experiments and in scaling microbial-enhanced oil recovery or bioremediation processes to the field. (c) 1994 John Wiley & Sons, Inc.

  2. Pulse Propagation in a simple probabilistic transport model

    Energy Technology Data Exchange (ETDEWEB)

    van Milligen, B. Ph. [Asociacion EURATOM-CIEMAT; Carreras, Benjamin A [ORNL; Lynch, Vickie E [ORNL; Sanchez, Raul [ORNL

    2007-01-01

    The response to perturbations of a simplified transport model is studied. The model is used as a paradigmatic example of transport controlled by a critical gradient. Long-time system behavior is diffusive when most of the system is sub-critical. However, when the critical mechanism becomes significant, it is observed to dominate the system behavior at both short- and long-time scales. While the pulse amplitude decays in an approximately diffusive manner at long times for weakly critical situations, the pulse shape is not self-similar.

  3. Cuttings Transport Models and Experimental Visualization of Underbalanced Horizontal Drilling

    Directory of Open Access Journals (Sweden)

    Na Wei

    2013-01-01

    Full Text Available Aerated underbalanced horizontal drilling technology has become the focus of the drilling industry at home and abroad, and one of the engineering core issues is the horizontal borehole cleaning. Therefore, calculating the minimum injection volume of gas and liquid accurately is essential for the construction in aerated underbalanced horizontal drilling. This paper establishes a physical model of carrying cuttings and borehole cleaning in wellbore of horizontal well and a critical transport mathematical model according to gas-liquid-solid flow mechanism and large plane dunes particle transport theory.

  4. Reconstructed jets in a multi-phase transport model

    Science.gov (United States)

    Ma, Guo-Liang

    2017-08-01

    With a framework of a multiphase transport model, we studied various of properties of fully reconstructed jets, including dijet asymmetry, jet shape, jet fragmentation function, jet azimuthal anisotropy, and overall momentum balance of dijet events. Our studies concentrate on the stage evolution of these full jet observables in heavy-ion collisions. We demonstrate that the medium modification effect on these observables mainly arises from strong interactions between jet and partonic matter, with further slight modifications from hadronization and hadronic rescatterings. Our model results provide a dynamical understanding of jet transport process in high-energy heavy-ion collisions.

  5. Modelling nitrate transport and turnover in a lowland catchment system

    Science.gov (United States)

    Wriedt, Gunter; Rode, Michael

    2006-08-01

    SummaryNitrate transport in groundwater dominated lowland catchment systems is influenced by complex and spatially distributed physical and chemical interactions. A modelling approach was developed combining a distributed soil nitrogen model with a three-dimensional groundwater model and a reactive transport model linking nitrate turnover and availability of reaction partners such as pyrite and organic matter. The modelling approach was applied to a hypothetical case study based on data from the pleistocene lowland catchment "Schaugraben" (20 km 2) in the North of Saxony-Anhalt, with focus on the investigation of interactions of spatially distributed transport and chemical processes. The modelling approach could successfully simulate transport and turnover of nitrate in a groundwater dominated catchment. The advancement of the nitrate front and the corresponding depletion of pyrite as well as the distribution of seepage fluxes and nitrate concentrations in seepage water in the channel system showed distinct spatial variation. Surface water nitrate concentrations corresponding to the average soil leachate concentrations were not completely reached after a simulation period of 200 years for a conservative transport simulation. Under reactive conditions, about 80% of the nitrate was lost due to denitrification. Given a uniformly distributed input of nitrate, drain loads developed in a sigmoidal curve defined only by travel time distribution. The average travel time was 93 years. A distributed input of nitrate resulted in reduction of travel time to 80 years due to the different arrangement of source areas and flow. The modelling approach is a step towards bridging the gap between simple large scale models and detailed small scale studies, maintaining process orientation while allowing to consider landscape heterogeneity.

  6. Intelligent Transportation and Evacuation Planning A Modeling-Based Approach

    CERN Document Server

    Naser, Arab

    2012-01-01

    Intelligent Transportation and Evacuation Planning: A Modeling-Based Approach provides a new paradigm for evacuation planning strategies and techniques. Recently, evacuation planning and modeling have increasingly attracted interest among researchers as well as government officials. This interest stems from the recent catastrophic hurricanes and weather-related events that occurred in the southeastern United States (Hurricane Katrina and Rita). The evacuation methods that were in place before and during the hurricanes did not work well and resulted in thousands of deaths. This book offers insights into the methods and techniques that allow for implementing mathematical-based, simulation-based, and integrated optimization and simulation-based engineering approaches for evacuation planning. This book also: Comprehensively discusses the application of mathematical models for evacuation and intelligent transportation modeling Covers advanced methodologies in evacuation modeling and planning Discusses principles a...

  7. A mathematical model of inter-terminal transportation

    DEFF Research Database (Denmark)

    Tierney, Kevin; Voß, Stefan; Stahlbock, Robert

    2014-01-01

    We present a novel integer programming model for analyzing inter-terminal transportation (ITT) in new and expanding sea ports. ITT is the movement of containers between terminals (sea, rail or otherwise) within a port. ITT represents a significant source of delay for containers being transshipped......, which costs ports money and affects a port’s reputation. Our model assists ports in analyzing the impact of new infrastructure, the placement of terminals, and ITT vehicle investments. We provide analysis of ITT at two ports, the port of Hamburg, Germany and the Maasvlakte 1 & 2 area of the port...... contains special structures to model the long term loading and unloading of vehicles, and our model is general enough to model a number of important real-world aspects of ITT, such as traffic congestion, penalized late container delivery, multiple ITT transportation modes, and port infrastructure...

  8. Analytical model of reactive transport processes with spatially variable coefficients.

    Science.gov (United States)

    Simpson, Matthew J; Morrow, Liam C

    2015-05-01

    Analytical solutions of partial differential equation (PDE) models describing reactive transport phenomena in saturated porous media are often used as screening tools to provide insight into contaminant fate and transport processes. While many practical modelling scenarios involve spatially variable coefficients, such as spatially variable flow velocity, v(x), or spatially variable decay rate, k(x), most analytical models deal with constant coefficients. Here we present a framework for constructing exact solutions of PDE models of reactive transport. Our approach is relevant for advection-dominant problems, and is based on a regular perturbation technique. We present a description of the solution technique for a range of one-dimensional scenarios involving constant and variable coefficients, and we show that the solutions compare well with numerical approximations. Our general approach applies to a range of initial conditions and various forms of v(x) and k(x). Instead of simply documenting specific solutions for particular cases, we present a symbolic worksheet, as supplementary material, which enables the solution to be evaluated for different choices of the initial condition, v(x) and k(x). We also discuss how the technique generalizes to apply to models of coupled multispecies reactive transport as well as higher dimensional problems.

  9. Validation of transport models in ASDEX Upgrade current ramps

    Energy Technology Data Exchange (ETDEWEB)

    Fietz, Sina; Hobirk, Joerg; Fable, Emiliano; Fischer, Rainer; Fuchs, Christoph; Pereverzev, Grigori; Ryter, Francois [Max Planck Institut fuer Plasmaphysik, EURATOM Association, Garching (Germany); Collaboration: the ASDEX Upgrade Team

    2011-07-01

    In order to prepare adequate ramp up and down scenarios for ITER, understanding the physics of transport during the current ramps is essential. The aim of the work was to assess the capability of several transport models to reproduce the experimental data during the current ramps. For this purpose, the calculated temperature profiles from different transport models, i.e. Coppi-Tang, Neo-Alcator, Bohm-Gyrobohm, critical gradient model and H98/2 scaling-based are compared to experimental temperature profiles under different conditions. The strong variation of the experimental electron temperature profiles are partly reproduced by the models. The importance of central and edge radiation will be emphasized, as well as the main transport properties of the models, especially in the case of strong local electron heating (ECRH). To investigate the control capabilities of a Tokamak, particularly with regard to ITER, the impact on global plasma parameters like the internal inductance and the stored energy is also investigated.

  10. Incorporating transportation network modeling tools within transportation economic impact studies of disasters

    Directory of Open Access Journals (Sweden)

    Yi Wen

    2014-08-01

    Full Text Available Transportation system disruption due to a disaster results in "ripple effects" throughout the entire transportation system of a metropolitan region. Many researchers have focused on the economic costs of transportation system disruptions in transportation-related industries, specifïcally within commerce and logistics, in the assessment of the regional economic costs. However, the foundation of an assessment of the regional economic costs of a disaster needs to include the evaluation of consumer surplus in addition to the direct cost for reconstruction of the regional transportation system. The objective of this study is to propose a method to estimate the regional consumer surplus based on indirect economic costs of a disaster on intermodal transportation systems in the context of diverting vehicles and trains. The computational methods used to assess the regional indirect economic costs sustained by the highway and railroad system can utilize readily available state departments of transportation (DOTs and metropolitan planning organizations (MPOs traffic models allowing prioritization of regional recovery plans after a disaster and strengthening of infrastructure before a disaster. Hurricane Katrina is one of the most devastating hurricanes in the history of the United States. Due to the significance of Hurricane Katrina, a case study is presented to evaluate consumer surplus in the Gulf Coast Region of Mississippi. Results from the case study indicate the costs of rerouting and congestion delays in the regional highway system and the rent costs of right-of-way in the regional railroad system are major factors of the indirect costs in the consumer surplus.

  11. Modeling biogechemical reactive transport in a fracture zone

    Energy Technology Data Exchange (ETDEWEB)

    Molinero, Jorge; Samper, Javier; Yang, Chan Bing, and Zhang, Guoxiang; Guoxiang, Zhang

    2005-01-14

    A coupled model of groundwater flow, reactive solute transport and microbial processes for a fracture zone of the Aspo site at Sweden is presented. This is the model of the so-called Redox Zone Experiment aimed at evaluating the effects of tunnel construction on the geochemical conditions prevailing in a fracture granite. It is found that a model accounting for microbially-mediated geochemical processes is able to reproduce the unexpected measured increasing trends of dissolved sulfate and bicarbonate. The model is also useful for testing hypotheses regarding the role of microbial processes and evaluating the sensitivity of model results to changes in biochemical parameters.

  12. Coupling of Groundwater Transport and Plant Uptake Models

    DEFF Research Database (Denmark)

    Rein, Arno; Bauer-Gottwein, Peter; Trapp, Stefan

    2010-01-01

    Plants significantly influence contaminant transport and fate. Important processes are uptake of soil and groundwater contaminants, as well as biodegradation in plants and their root zones. Models for the prediction of chemical uptake into plants are required for the setup of mass balances in env...... to groundwater transport simulation tools. Exemplary simulations of plant uptake were carried out, in order to estimate concentrations in the soilplant- air system and the influence of plants on contaminant mass fluxes from soil to groundwater.......Plants significantly influence contaminant transport and fate. Important processes are uptake of soil and groundwater contaminants, as well as biodegradation in plants and their root zones. Models for the prediction of chemical uptake into plants are required for the setup of mass balances...

  13. Review of modeling and control during transport airdrop process

    Directory of Open Access Journals (Sweden)

    Bin Xu

    2016-12-01

    Full Text Available This article presents the review of modeling and control during the airdrop process of transport aircraft. According to the airdrop height, technology can be classified into high and low altitude airdrop and in this article, the research is reviewed based on the two scenarios. While high altitude airdrop is mainly focusing on the precise landing control of cargo, the low altitude flight airdrop is on the control of transport aircraft dynamics to ensure flight safety. The history of high precision airdrop system is introduced first, and then the modeling and control problem of the ultra low altitude airdrop in transport aircraft is presented. Finally, the potential problems and future direction of low altitude airdrop are discussed.

  14. 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...... 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...... by the rate of mass transport only. A consequence of the source or sink term, is the assumption that equilibrium is reached instantaneously in each time step considered. Some numerical problems was found, where the residual requirements for the chemical equilibrium was not reached. Small imbalances, in e...

  15. A new turbulence-based model for sand transport

    Science.gov (United States)

    Mayaud, Jerome; Wiggs, Giles; Bailey, Richard

    2016-04-01

    Knowledge of the changing rate of sediment flux in space and time is essential for quantifying surface erosion and deposition in desert landscapes. While many aeolian studies have relied on time-averaged parameters such as wind velocity (U) and wind shear velocity (u*) to determine sediment flux, there is increasing evidence that high-frequency turbulence is an important driving force behind the entrainment and transport of sand. However, turbulence has yet to be incorporated into a functional sand transport model that can be used for predictive purposes. In this study we present a new transport model (the 'turbulence model') that accounts for high-frequency variations in the horizontal (u) and vertical (w) components of wind flow. The turbulence model is fitted to wind velocity and sediment transport data from a field experiment undertaken in Namibia's Skeleton Coast National Park, and its performance at three temporal resolutions (10 Hz, 1 Hz, 1 min) is compared to two existing models that rely on time-averaged wind velocity data (Radok, 1977; Dong et al., 2003). The validity of the three models is analysed under a variety of saltation conditions, using a 2-hour (1 Hz measurement resolution) dataset from the Skeleton Coast and a 5-hour (1 min measurement resolution) dataset from the southwestern Kalahari Desert. The turbulence model is shown to outperform the Radok and Dong models when predicting total saltation count over the three experimental periods. For all temporal resolutions presented in this study (10 Hz-10 min), the turbulence model predicted total saltation count to within at least 0.34%, whereas the Radok and Dong models over- or underestimated total count by up to 5.50% and 20.53% respectively. The strong performance of the turbulence model can be attributed to a lag in mass flux response built into its formulation, which can be adapted depending on the temporal resolution of investigation. This accounts for the inherent lag within the physical

  16. Comparison of mechanistic transport cycle models of ABC exporters.

    Science.gov (United States)

    Szöllősi, Dániel; Rose-Sperling, Dania; Hellmich, Ute A; Stockner, Thomas

    2018-04-01

    ABC (ATP binding cassette) transporters, ubiquitous in all kingdoms of life, carry out essential substrate transport reactions across cell membranes. Their transmembrane domains bind and translocate substrates and are connected to a pair of nucleotide binding domains, which bind and hydrolyze ATP to energize import or export of substrates. Over four decades of investigations into ABC transporters have revealed numerous details from atomic-level structural insights to their functional and physiological roles. Despite all these advances, a comprehensive understanding of the mechanistic principles of ABC transporter function remains elusive. The human multidrug resistance transporter ABCB1, also referred to as P-glycoprotein (P-gp), is one of the most intensively studied ABC exporters. Using ABCB1 as the reference point, we aim to compare the dominating mechanistic models of substrate transport and ATP hydrolysis for ABC exporters and to highlight the experimental and computational evidence in their support. In particular, we point out in silico studies that enhance and complement available biochemical data. "This article is part of a Special Issue entitled: Beyond the Structure-Function Horizon of Membrane Proteins edited by Ute Hellmich, Rupak Doshi and Benjamin McIlwain." Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  17. Transport models for relativistic heavy-ion collisions at Relativistic ...

    Indian Academy of Sciences (India)

    2015-04-29

    Apr 29, 2015 ... Transport models for relativistic heavy-ion collisions at Relativistic Heavy Ion Collider and Large Hadron Collider. Subrata Pal. Volume 84 Issue 5 May 2015 pp ... Subrata Pal1. Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India ...

  18. Tracking cellular telephones as an input for developing transport models

    CSIR Research Space (South Africa)

    Cooper, Antony K

    2010-08-01

    Full Text Available of tracking cellular telephones and using the data to populate transport and other models. We report here on one of the pilots, known as DYNATRACK (Dynamic Daily Path Tracking), a larger experiment conducted in 2007 with a more heterogeneous group of commuters...

  19. Development of numerical Grids for UZ Flow and Transport Modeling

    Energy Technology Data Exchange (ETDEWEB)

    P. Dobson

    2004-08-31

    This report describes the methods used to develop numerical grids of the unsaturated hydrogeologic system beneath Yucca Mountain, Nevada. Numerical grid generation is an integral part of the development of the unsaturated zone (UZ) flow and transport model, a complex, three-dimensional (3-D) model of Yucca Mountain. This revision contains changes made to improve the clarity of the description of grid generation. The numerical grids, developed using current geologic, hydrogeologic, and mineralogic data, provide the necessary framework to: (1) develop calibrated hydrogeologic property sets and flow fields, (2) test conceptual hypotheses of flow and transport, and (3) predict flow and transport behavior under a variety of climatic and thermal-loading conditions. The technical scope, content, and management for the current revision of this report are described in the planning document ''Technical Work Plan for: Unsaturated Zone Flow Analysis and Model Report Integration'' (BSC 2004 [DIRS 169654], Section 2). Grids generated and documented in this report supersede those documented in Revision 00 of this report, ''Development of Numerical Grids for UZ Flow and Transport Modeling'' (BSC 2001 [DIRS 159356]). The grids presented in this report are the same as those developed in Revision 01 (BSC 2003 [DIRS 160109]); however, the documentation of the development of the grids in Revision 02 has been updated to address technical inconsistencies and achieve greater transparency, readability, and traceability. The constraints, assumptions, and limitations associated with this report are discussed in the appropriate sections that follow.

  20. Modeling marine surface microplastic transport to assess optimal removal locations

    NARCIS (Netherlands)

    Sherman, Peter; Van Sebille, Erik|info:eu-repo/dai/nl/304831921

    2016-01-01

    Marine plastic pollution is an ever-increasing problem that demands immediate mitigation and reduction plans. Here, a model based on satellite-tracked buoy observations and scaled to a large data set of observations on microplastic from surface trawls was used to simulate the transport of plastics

  1. Modeling the fate and transport of plastic debris in freshwaters

    NARCIS (Netherlands)

    Kooi, Merel; Besseling, Ellen; Kroeze, Carolien; Wenzel, van Annemarie P.; Koelmans, Albert A.

    2018-01-01

    Contamination with plastic debris has been recognized as one of today’s major environmental quality problems. Because most of the sources are land based, concerns are increasingly focused on the freshwater and terrestrial environment. Fate and transport models for plastic debris can complement

  2. In vitro placental model optimization for nanoparticle transport studies

    DEFF Research Database (Denmark)

    Cartwright, Laura; Poulsen, Marie Sønnegaard; Nielsen, Hanne Mørck

    2012-01-01

    on polycarbonate membranes (3.0 μm pore size) was four times higher for the 50 nm particles compared with the 100 nm particles. CONCLUSION: The BeWo cell line has been optimized and shown to be a valid in vitro model for studying the transplacental transport of nanoparticles. Fluorescent polystyrene nanoparticle...

  3. Development of a transport model for the microbial degradation of ...

    African Journals Online (AJOL)

    A mathematical model for first order reaction rate under isothermal condition was developed for predicting the diffusivity and transport rate of anthracene and pyrene during biodegradation using two microbial strains (corynebacteria spp and pseudomonas putida) in a heterogeneous porous medium. The formulation ...

  4. Solving vertical transport and chemistry in air pollution models

    NARCIS (Netherlands)

    P.J.F. Berkvens (Patrick); M.A. Botchev; J.G. Verwer (Jan); M.C. Krol; W. Peters

    2000-01-01

    textabstractFor the time integration of stiff transport-chemistry problems from air pollution modelling, standard ODE solvers are not feasible due to the large number of species and the 3D nature. The popular alternative, standard operator splitting, introduces artificial transients for short-lived

  5. Modelling two-phase transport of 3H/3He

    NARCIS (Netherlands)

    Visser, A.; Schaap, J.D.; Leijnse, T.; Broers, H.P.; Bierkens, M.F.P.

    2008-01-01

    Degassing of groundwater by excess denitrification of agricultural pollution complicates the interpretation of 3H/3He data and hinders the estimation of travel times in nitrate pollution studies. In this study we used a two-phase flow and transport model (STOMP) to evaluate the method presented by

  6. Numerical modelling on fate and transport of petroleum ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 124; Issue 3. Numerical modelling on ... The vertical transport of petroleum hydrocarbons from a surface spill through an unsaturated subsurface system is of major concern in assessing the vulnerability of groundwater contamination. A realistic representation on ...

  7. Solving vertical transport and chemistry in air pollution models

    NARCIS (Netherlands)

    Berkvens, P.J.F.; Bochev, Mikhail A.; Krol, M.C.; Peters, W.; Verwer, J.G.

    2002-01-01

    For the time integration of stiff transport-chemistry problems from air pollution modelling, standard ODE solvers are not feasible due to the large number of species and the 3D nature. The popular alternative, standard operator splitting, introduces artificial transients for short-lived species.

  8. Transport of Pathogen Surrogates in Soil Treatment Units: Numerical Modeling

    Directory of Open Access Journals (Sweden)

    Ivan Morales

    2014-04-01

    Full Text Available Segmented mesocosms (n = 3 packed with sand, sandy loam or clay loam soil were used to determine the effect of soil texture and depth on transport of two septic tank effluent (STE-borne microbial pathogen surrogates—green fluorescent protein-labeled E. coli (GFPE and MS-2 coliphage—in soil treatment units. HYDRUS 2D/3D software was used to model the transport of these microbes from the infiltrative surface. Mesocosms were spiked with GFPE and MS-2 coliphage at 105 cfu/mL STE and 105–106 pfu/mL STE, respectively. In all soils, removal rates were >99.99% at 25 cm. The transport simulation compared (1 optimization; and (2 trial-and-error modeling approaches. Only slight differences between the transport parameters were observed between these approaches. Treating both the die-off rates and attachment/detachment rates as variables resulted in an overall better model fit, particularly for the tailing phase of the experiments. Independent of the fitting procedure, attachment rates computed by the model were higher in sandy and sandy loam soils than clay, which was attributed to unsaturated flow conditions at lower water content in the coarser-textured soils. Early breakthrough of the bacteria and virus indicated the presence of preferential flow in the system in the structured clay loam soil, resulting in faster movement of water and microbes through the soil relative to a conservative tracer (bromide.

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

    Indian Academy of Sciences (India)

    ... transport and defect phenomena involoved in the growth process with the ultimate aim of integrating them into a comprehensive numerical model. The sources of dislocation nucleation in the growing crystal are discussed, and the propagation and multiplication of these under the action of thermal stresses is discussed.

  10. A Cellular Automata Models of Evolution of Transportation Networks

    Directory of Open Access Journals (Sweden)

    Mariusz Paszkowski

    2002-01-01

    Full Text Available We present a new approach to modelling of transportation networks. Supply of resources and their influence on the evolution of the consuming environment is a princqral problem considered. ne present two concepts, which are based on cellular automata paradigm. In the first model SCAM4N (Simple Cellular Automata Model of Anastomosing Network, the system is represented by a 2D mesh of elementary cells. The rules of interaction between them are introduced for modelling ofthe water flow and other phenomena connected with anastomosing river: Due to limitations of SCAMAN model, we introduce a supplementary model. The MANGraCA (Model of Anastomosing Network with Graph of Cellular Automata model beside the classical mesh of automata, introduces an additional structure: the graph of cellular automata, which represents the network pattern. Finally we discuss the prospective applications ofthe models. The concepts of juture implementation are also presented.

  11. Significance of flow clustering and sequencing on sediment transport: 1D sediment transport modelling

    Science.gov (United States)

    Hassan, Kazi; Allen, Deonie; Haynes, Heather

    2016-04-01

    This paper considers 1D hydraulic model data on the effect of high flow clusters and sequencing on sediment transport. Using observed flow gauge data from the River Caldew, England, a novel stochastic modelling approach was developed in order to create alternative 50 year flow sequences. Whilst the observed probability density of gauge data was preserved in all sequences, the order in which those flows occurred was varied using the output from a Hidden Markov Model (HMM) with generalised Pareto distribution (GP). In total, one hundred 50 year synthetic flow series were generated and used as the inflow boundary conditions for individual flow series model runs using the 1D sediment transport model HEC-RAS. The model routed graded sediment through the case study river reach to define the long-term morphological changes. Comparison of individual simulations provided a detailed understanding of the sensitivity of channel capacity to flow sequence. Specifically, each 50 year synthetic flow sequence was analysed using a 3-month, 6-month or 12-month rolling window approach and classified for clusters in peak discharge. As a cluster is described as a temporal grouping of flow events above a specified threshold, the threshold condition used herein is considered as a morphologically active channel forming discharge event. Thus, clusters were identified for peak discharges in excess of 10%, 20%, 50%, 100% and 150% of the 1 year Return Period (RP) event. The window of above-peak flows also required cluster definition and was tested for timeframes 1, 2, 10 and 30 days. Subsequently, clusters could be described in terms of the number of events, maximum peak flow discharge, cumulative flow discharge and skewness (i.e. a description of the flow sequence). The model output for each cluster was analysed for the cumulative flow volume and cumulative sediment transport (mass). This was then compared to the total sediment transport of a single flow event of equivalent flow volume

  12. Sample selection and taste correlation in discrete choice transport modelling

    DEFF Research Database (Denmark)

    Mabit, Stefan Lindhard

    2008-01-01

    many issues that deserve attention. This thesis investigates how sample selection can affect estimation of discrete choice models and how taste correlation should be incorporated into applied mixed logit estimation. Sampling in transport modelling is often based on an observed trip. This may cause...... explain counterintuitive results in value of travel time estimation. However, the results also point at the difficulty of finding suitable instruments for the selection mechanism. Taste heterogeneity is another important aspect of discrete choice modelling. Mixed logit models are designed to capture...... observed as well as unobserved heterogeneity in tastes. But just as there are many reasons to expect unobserved heterogeneity, there is no reason to expect these tastes for different things to be independent. This is rarely accounted for in transportation research. Here three separate investigations...

  13. Paving the road from transport models to “new mobilities” models

    DEFF Research Database (Denmark)

    Wind, Simon; Jensen, Ole B.; Kaplan, Sigal

    2012-01-01

    For half a century, tremendous efforts have been invested in developing transport models as a decision aid for policy makers in designing effective policy interventions and deciding among costly public projects for the benefit of the population. Transport and activity-based models are often criti...

  14. A wave-resolving model for nearshore suspended sediment transport

    Science.gov (United States)

    Ma, Gangfeng; Chou, Yi-Ju; Shi, Fengyan

    2014-05-01

    This paper presents a wave-resolving sediment transport model, which is capable of simulating sediment suspension in the field-scale surf zone. The surf zone hydrodynamics is modeled by the non-hydrostatic model NHWAVE (Ma et al., 2012). The turbulent flow and suspended sediment are simulated in a coupled manner. Three effects of suspended sediment on turbulent flow field are considered: (1) baroclinic forcing effect; (2) turbulence damping effect and (3) bottom boundary layer effect. Through the validation with the laboratory measurements of suspended sediment under nonbreaking skewed waves and surfzone breaking waves, we demonstrate that the model can reasonably predict wave-averaged sediment profiles. The model is then utilized to simulate a rip current field experiment (RCEX) and nearshore suspended sediment transport. The offshore sediment transport by rip currents is captured by the model. The effects of suspended sediment on self-suspension are also investigated. The turbulence damping and bottom boundary layer effects are significant on sediment suspension. The suspended sediment creates a stably stratified water column, damping fluid turbulence and reducing turbulent diffusivity. The suspension of sediment also produces a stably stratified bottom boundary layer. Thus, the drag coefficient and bottom shear stress are reduced, causing less sediment pickup from the bottom. The cross-shore suspended sediment flux is analyzed as well. The mean Eulerian suspended sediment flux is shoreward outside the surf zone, while it is seaward in the surf zone.

  15. Combining Deterministic structures and stochastic heterogeneity for transport modeling

    Science.gov (United States)

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

    2017-04-01

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

  16. Modeling transport kinetics in clinoptilolite-phosphate rock systems

    Science.gov (United States)

    Allen, E. R.; Ming, D. W.; Hossner, L. R.; Henninger, D. L.

    1995-01-01

    Nutrient release in clinoptilolite-phosphate rock (Cp-PR) systems occurs through dissolution and cation-exchange reactions. Investigating the kinetics of these reactions expands our understanding of nutrient release processes. Research was conducted to model transport kinetics of nutrient release in Cp-PR systems. The objectives were to identify empirical models that best describe NH4, K, and P release and define diffusion-controlling processes. Materials included a Texas clinoptilolite (Cp) and North Carolina phosphate rock (PR). A continuous-flow thin-disk technique was used. Models evaluated included zero order, first order, second order, parabolic diffusion, simplified Elovich, Elovich, and power function. The power-function, Elovich, and parabolic-diffusion models adequately described NH4, K, and P release. The power-function model was preferred because of its simplicity. Models indicated nutrient release was diffusion controlled. Primary transport processes controlling nutrient release for the time span observed were probably the result of a combination of several interacting transport mechanisms.

  17. Modeling surf zone tracer plumes: 2. Transport and dispersion

    Science.gov (United States)

    Clark, David B.; Feddersen, Falk; Guza, R. T.

    2011-11-01

    Five surf zone dye tracer releases from the HB06 experiment are simulated with a tracer advection diffusion model coupled to a Boussinesq surf zone model (funwaveC). Model tracer is transported and stirred by currents and eddies and diffused with a breaking wave eddy diffusivity, set equal to the breaking wave eddy viscosity, and a small (0.01 m2 s-1) background diffusivity. Observed and modeled alongshore parallel tracer plumes, transported by the wave driven alongshore current, have qualitatively similar cross-shore structures. Although the model skill for mean tracer concentration is variable (from negative to 0.73) depending upon release, cross-shore integrated tracer moments (normalized by the cross-shore tracer integral) have consistently high skills (≈0.9). Modeled and observed bulk surf zone cross-shore diffusivity estimates are also similar, with 0.72 squared correlation and skill of 0.4. Similar to the observations, the model bulk (absolute) cross-shore diffusivity is consistent with a mixing length parameterization based on low-frequency (0.001-0.03 Hz) eddies. The model absolute cross-shore dispersion is dominated by stirring from surf zone eddies and does not depend upon the presence of the breaking wave eddy diffusivity. Given only the bathymetry and incident wave field, the coupled Boussinesq-tracer model qualitatively reproduces the observed cross-shore absolute tracer dispersion, suggesting that the model can be used to study surf zone tracer dispersion mechanisms.

  18. Sediment and radionuclide transport in rivers: radionuclide transport modeling for Cattaraugus and Buttermilk Creeks, New York

    Energy Technology Data Exchange (ETDEWEB)

    Onishi, Y.; Yabusaki, S.B.; Kincaid, C.T.; Skaggs, R.L.; Walters, W.H.

    1982-12-01

    SERATRA, a transient, two-dimensional (laterally-averaged) computer model of sediment-contaminant transport in rivers, satisfactorily resolved the distribution of sediment and radionuclide concentrations in the Cattaraugus Creek stream system in New York. By modeling the physical processes of advection, diffusion, erosion, deposition, and bed armoring, SERATRA routed three sediment size fractions, including cohesive soils, to simulate three dynamic flow events. In conjunction with the sediment transport, SERATRA computed radionuclide levels in dissolved, suspended sediment, and bed sediment forms for four radionuclides (/sup 137/Cs, /sup 90/Sr, /sup 239/ /sup 240/Pu, and /sup 3/H). By accounting for time-dependent sediment-radionuclide interaction in the water column and bed, SERATA is a physically explicit model of radionuclide fate and migration. Sediment and radionuclide concentrations calculated by SERATA in the Cattaraugus Creek stream system are in reasonable agreement with measured values. SERATRA is in the field performance phase of an extensive testing program designed to establish the utility of the model as a site assessment tool. The model handles not only radionuclides but other contaminants such as pesticides, heavy metals and other toxic chemicals. Now that the model has been applied to four field sites, including the latest study of the Cattaraugus Creek stream system, it is recommended that a final model be validated through comparison of predicted results with field data from a carefully controlled tracer test at a field site. It is also recommended that a detailed laboratory flume be tested to study cohesive sediment transport, deposition, and erosion characteristics. The lack of current understanding of these characteristics is one of the weakest areas hindering the accurate assessment of the migration of radionuclides sorbed by fine sediments of silt and clay.

  19. Colloid transport in saturated porous media: Elimination of attachment efficiency in a new colloid transport model

    Science.gov (United States)

    Landkamer, Lee L.; Harvey, Ronald W.; Scheibe, Timothy D.; Ryan, Joseph N.

    2013-01-01

    A colloid transport model is introduced that is conceptually simple yet captures the essential features of colloid transport and retention in saturated porous media when colloid retention is dominated by the secondary minimum because an electrostatic barrier inhibits substantial deposition in the primary minimum. This model is based on conventional colloid filtration theory (CFT) but eliminates the empirical concept of attachment efficiency. The colloid deposition rate is computed directly from CFT by assuming all predicted interceptions of colloids by collectors result in at least temporary deposition in the secondary minimum. Also, a new paradigm for colloid re-entrainment based on colloid population heterogeneity is introduced. To accomplish this, the initial colloid population is divided into two fractions. One fraction, by virtue of physiochemical characteristics (e.g., size and charge), will always be re-entrained after capture in a secondary minimum. The remaining fraction of colloids, again as a result of physiochemical characteristics, will be retained “irreversibly” when captured by a secondary minimum. Assuming the dispersion coefficient can be estimated from tracer behavior, this model has only two fitting parameters: (1) the fraction of the initial colloid population that will be retained “irreversibly” upon interception by a secondary minimum, and (2) the rate at which reversibly retained colloids leave the secondary minimum. These two parameters were correlated to the depth of the Derjaguin-Landau-Verwey-Overbeek (DLVO) secondary energy minimum and pore-water velocity, two physical forces that influence colloid transport. Given this correlation, the model serves as a heuristic tool for exploring the influence of physical parameters such as surface potential and fluid velocity on colloid transport.

  20. Model documentation report: Transportation sector model of the National Energy Modeling System

    Energy Technology Data Exchange (ETDEWEB)

    1994-03-01

    This report documents the objectives, analytical approach and development of the National Energy Modeling System (NEMS) Transportation Model (TRAN). The report catalogues and describes the model assumptions, computational methodology, parameter estimation techniques, model source code, and forecast results generated by the model. This document serves three purposes. First, it is a reference document providing a detailed description of TRAN for model analysts, users, and the public. Second, this report meets the legal requirements of the Energy Information Administration (EIA) to provide adequate documentation in support of its statistical and forecast reports (Public Law 93-275, 57(b)(1)). Third, it permits continuity in model development by providing documentation from which energy analysts can undertake model enhancements, data updates, and parameter refinements.

  1. Modeling Mercury Fate and Transport in Aquatic Systems

    Science.gov (United States)

    Massoudieh, Arash; Žagar, Dušan; Green, Peter G.; Cabrera-Toledo, Carlos; Horvat, Milena; Ginn, Timothy R.; Barkouki, Tammer; Weathers, Tess; Bombardelli, Fabian A.

    Mercury in the aquatic environment is a neurotoxin with several known adverse effects on the natural ecosystem and the human health. Mathematical modeling is a cost-effective way for assessing the risk associated with mercury to aquatic organisms and for developing management plans for the reduction of mercury exposure in such systems. However, the analysis of mercury fate and transport in the aquatic environment requires multiple disciplines of science ranging from sediment transport and hydraulics, to geochemistry and microbiology. Also, it involves the knowledge of some less understood processes such as the microbial and diagenetic processes affecting the chemical speciation of mercury and various mechanisms involved in the mass-exchange of mercury species between the benthic sediments and the overlying water. Due to these complexities, there are many challenges involved in developing an integrated mercury fate and transport model in aquatic systems. This paper identifies the various processes that are potentially important in mercury fate and transport as well as the knowns and unknowns about these processes. Also, an integrated multi-component reactive transport modeling approach is suggested to capture several of those processes. This integrated modeling framework includes the coupled advective-dispersive transport of mercury species in the water body, both in dissolved phase and as associated to mobile suspended sediments. The flux of mercury in the benthic sediments as a result of diffusive mass exchange, bio-dispersion, and hyporheic flow, and the flow generated due to consolidation of newly deposited sediments is also addressed. The model considers in addition the deposition and resuspension of sediments and their effect on the mass exchange of mercury species between the top water and the benthic sediments. As for the biogeochemical processes, the effect of redox stratification and activities of sulfate and iron-reducing bacteria on the methylation of

  2. Modeling and simulation of transport phenomena in ionic gels

    Science.gov (United States)

    Leichsenring, Peter; Wallmersperger, Thomas

    2015-04-01

    Ionic hydrogels belong to the class of polyelectrolyte gels or ionic gels. Their ability to swell or shrink under different environmental conditions such as change of pH, ion concentration or temperature make them promising materials, e.g. for microsensoric or microactuatoric devices. The hydrogel swelling exhibits nonlinear effects due to the occurrence of different interacting transport phenomena. Numerical simulations are an essential part in the ongoing development of microsensors and microactuators. In order to determine transport effects due to diffusion, migration and convection a multiphase mesoscale model based on the Theory of Porous Media is applied. The governing field equations are solved in the transient regime by applying the Finite Element Method. By means of the derived numerical framework a detailed investigation of the different transport phenomena is carried out. Numerical experiments are performed to characterize the dominating transfer phenomena for ionic gels under chemical stimulation.

  3. Multimodal Transport System Coevolution Model Based on Synergetic Theory

    Directory of Open Access Journals (Sweden)

    Fenling Feng

    2015-01-01

    Full Text Available This study investigates multimodal transport system evolution law with the consideration of synergetic theory. Compared with previous studies, this paper focuses on understanding influencing factors of system collaborative development. In particular, we have applied a multimodal system order parameter model to obtain the order parameter. Based on order parameters, the coevolution equations of the multimodal transport system are constructed with consideration of cooperation and competitive relationship between the subsystems. We set out the multimodal system followed the coevolution law of the freight system and dominated by the combined effects of order parameter line length and freight density. The results show that the coordination effects between railway, road, and water subsystems are stronger than aviation subsystem; the railway system is the short plank of the system. Some functional implications from this study are also discussed. Finally the results indicate that expansion of railway system capacity and mutual cooperation within the subsystems are required to reach an optimal multimodal transport system.

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

    DEFF Research Database (Denmark)

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

    2004-01-01

    The performance of a heterogeneous material like concrete is largely determined by the many interfaces in this material. This contribution focuses on the potential of numerical simulation models to investigate the character of the matrix-aggregate interfacial zone and to simulate hydration-induce......-induced moisture transport from the water-rich interfacial zone to the drying bulk paste. Typical features of the simulation model are presented, as well as results of the numerical analysis of the effect of moisture transport within the hardening paste.......The performance of a heterogeneous material like concrete is largely determined by the many interfaces in this material. This contribution focuses on the potential of numerical simulation models to investigate the character of the matrix-aggregate interfacial zone and to simulate hydration...

  5. Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms

    Science.gov (United States)

    Widdows, Kate L.; Panitchob, Nuttanont; Crocker, Ian P.; Please, Colin P.; Hanson, Mark A.; Sibley, Colin P.; Johnstone, Edward D.; Sengers, Bram G.; Lewis, Rohan M.; Glazier, Jocelyn D.

    2015-01-01

    Uptake of system L amino acid substrates into isolated placental plasma membrane vesicles in the absence of opposing side amino acid (zero-trans uptake) is incompatible with the concept of obligatory exchange, where influx of amino acid is coupled to efflux. We therefore hypothesized that system L amino acid exchange transporters are not fully obligatory and/or that amino acids are initially present inside the vesicles. To address this, we combined computational modeling with vesicle transport assays and transporter localization studies to investigate the mechanisms mediating [14C]l-serine (a system L substrate) transport into human placental microvillous plasma membrane (MVM) vesicles. The carrier model provided a quantitative framework to test the 2 hypotheses that l-serine transport occurs by either obligate exchange or nonobligate exchange coupled with facilitated transport (mixed transport model). The computational model could only account for experimental [14C]l-serine uptake data when the transporter was not exclusively in exchange mode, best described by the mixed transport model. MVM vesicle isolates contained endogenous amino acids allowing for potential contribution to zero-trans uptake. Both L-type amino acid transporter (LAT)1 and LAT2 subtypes of system L were distributed to MVM, with l-serine transport attributed to LAT2. These findings suggest that exchange transporters do not function exclusively as obligate exchangers.—Widdows, K. L., Panitchob, N., Crocker, I. P., Please, C. P., Hanson, M. A., Sibley, C. P., Johnstone, E. D., Sengers, B. G., Lewis, R. M., Glazier, J. D. Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms. PMID:25761365

  6. Batch and column studies of adsorption of Li, Ni and Br by a reference sand for contaminant transport experiments

    Energy Technology Data Exchange (ETDEWEB)

    Seigel, M.D. [Sandia National Labs., Albuquerque, NM (United States); Ward, D.B.; Bryan, C.R. [Univ. of New Mexico, Albuquerque, NM (United States)] [and others

    1995-09-01

    A processed quartz sand (Wedron 510), mined from the St. Peter sandstone, has been characterized by a variety of chemical and physical methods for use as a reference porous media in transport model validation experiments. Wedron 510 sand was used in an intermediate-scale experiment involving migration of Ni, Li and Br through a 6-m high x 3-m diameter caisson. Ni and Li adsorption/desorption, and Li/Ni site-competition experiments yielded information on the importance of the trace mineral phases to adsorption of Li and Ni by the sand. The presence of an iron hydroxide coating similar to goethite on the sand grains is suggested by visual observation and leaching experiments. Kaolinite was identified by SEM and XRD as a significant trace mineral phase in the sand and occurs as small particles coating the sand grains. Quartz, the predominant constituent of the sand by weight, does not appear to contribute significantly to the adsorption properties of the sand. Qualitatively, the adsorption properties of the sand can be adequately modeled as a two-mineral system (goethite and kaolinite). The studies described in this report should provide a basis for understanding transport of Ni, Li and Br through porous media similar to the reference sand. Techniques were developed for obtaining parameter values for surface complexation and kinetic adsorption models for the sand and its mineral components. These constants can be used directly in coupled hydrogeochemical transport codes. The techniques should be useful for characterization of other natural materials and elements in high-level nuclear waste in support of coupled hydrogeochemical transport calculations for Yucca Mountain.

  7. Modelling of electron transport and of sawtooth activity in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Angioni, C

    2001-10-01

    Transport phenomena in tokamak plasmas strongly limit the particle and energy confinement and represent a crucial obstacle to controlled thermonuclear fusion. Within the vast framework of transport studies, three topics have been tackled in the present thesis: first, the computation of neoclassical transport coefficients for general axisymmetric equilibria and arbitrary collisionality regime; second, the analysis of the electron temperature behaviour and transport modelling of plasma discharges in the Tokamak a configuration Variable (TCV); third, the modelling and simulation of the sawtooth activity with different plasma heating conditions. The work dedicated to neoclassical theory has been undertaken in order to first analytically identify a set of equations suited for implementation in existing Fokker-Planck codes. Modifications of these codes enabled us to compute the neoclassical transport coefficients considering different realistic magnetic equilibrium configurations and covering a large range of variation of three key parameters: aspect ratio, collisionality, and effective charge number. A comparison of the numerical results with an analytical limit has permitted the identification of two expressions for the trapped particle fraction, capable of encapsulating the geometrical effects and thus enabling each transport coefficient to be fitted with a single analytical function. This has allowed us to provide simple analytical formulae for all the neoclassical transport coefficients valid for arbitrary aspect ratio and collisionality in general realistic geometry. This work is particularly useful for a correct evaluation of the neoclassical contribution in tokamak scenarios with large bootstrap cur- rent fraction, or improved confinement regimes with low anomalous transport and for the determination of the plasma current density profile, since the plasma conductivity is usually assumed neoclassical. These results have been included in the plasma transport code

  8. Linking air and water transport in intact soils to macropore characteristics inferred from X-ray computed tomography

    DEFF Research Database (Denmark)

    Katuwal, Sheela; Nørgaard, Trine; Møldrup, Per

    2015-01-01

    Soil macropores often control fluid flow and solute transport, and quantification of macropore characteristics including their variability in space and time are essential to predict soil hydraulic and hydrogeochemical functions. In this study, measurements of air and solute transport properties a...

  9. COMPARISON OF RF CAVITY TRANSPORT MODELS FOR BBU SIMULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Ilkyoung Shin,Byung Yunn,Todd Satogata,Shahid Ahmed

    2011-03-01

    The transverse focusing effect in RF cavities plays a considerable role in beam dynamics for low-energy beamline sections and can contribute to beam breakup (BBU) instability. The purpose of this analysis is to examine RF cavity models in simulation codes which will be used for BBU experiments at Jefferson Lab and improve BBU simulation results. We review two RF cavity models in the simulation codes elegant and TDBBU (a BBU simulation code developed at Jefferson Lab). elegant can include the Rosenzweig-Serafini (R-S) model for the RF focusing effect. Whereas TDBBU uses a model from the code TRANSPORT which considers the adiabatic damping effect, but not the RF focusing effect. Quantitative comparisons are discussed for the CEBAF beamline. We also compare the R-S model with the results from numerical simulations for a CEBAF-type 5-cell superconducting cavity to validate the use of the R-S model as an improved low-energy RF cavity transport model in TDBBU. We have implemented the R-S model in TDBBU. It will improve BBU simulation results to be more matched with analytic calculations and experimental results.

  10. Modeling of Switching and Hysteresis in Molecular Transport

    Science.gov (United States)

    Samanta, Manoj P.; Partridge, Harry (Technical Monitor)

    2002-01-01

    The conventional way of modeling current transport in two and three terminal molecular devices could be inadequate for certain cases involving switching and hysteresis. Here we present an alternate approach. Contrary to the regular way where applied bias directly modulates the conducting energy levels of the molecule, our method introduces a nonlinear potential energy surface varying with the applied bias as a control parameter. A time-dynamics is also introduced properly accounting for switching and hysteresis behavior. Although the model is phenomenological at this stage, we believe any detailed model would contain similar descriptions at its core.

  11. The dual-gate lumen model of renal monoamine transport

    Directory of Open Access Journals (Sweden)

    Marty Hinz

    2010-07-01

    Full Text Available Marty Hinz1, Alvin Stein2, Thomas Uncini31Clinical Research, NeuroResearch Clinics, Inc. Cape Coral, Florida, USA; 2Stein Orthopedic Associates, Plantation, Florida, USA; 3DBS Labs, Duluth, Minnesota, USAAbstract: The three-phase response of urinary serotonin and dopamine in subjects ­simultaneously taking amino acid precursors of serotonin and dopamine has been defined.1,2 No model exists regarding the renal etiology of the three-phase response. This writing outlines a model explaining the origin of the three-phase response of urinary serotonin and dopamine. A “dual-gate lumen transporter model” for the basolateral monoamine transporters of the kidneys is proposed as being the etiology of the three-phase urinary serotonin and dopamine responses.Purpose: The purpose of this writing is to document the internal renal function model that has evolved in research during large-scale assay with phase interpretation of urinary serotonin and dopamine.Patients and methods: In excess of 75,000 urinary monoamine assays from more than 7,500 patients were analyzed. The serotonin and the dopamine phase were determined for specimens submitted in the competitive inhibition state. The phase determination findings were then correlated with peer-reviewed literature.Results: The correlation between the three-phase response of urinary serotonin and dopamine with internal renal processes of the bilateral monoamine transporter and the apical monoamine transporter of the proximal convoluted renal tubule cells is defined.Conclusion: The phase of urinary serotonin and dopamine is dependent on the status of the serotonin gate, dopamine gate, and lumen of the basolateral monoamine transporter while in the competitive inhibition state.Keywords: serotonin, dopamine, basolateral, apical, kidney, proximal

  12. Modelling Transcapillary Transport of Fluid and Proteins in Hemodialysis Patients.

    Directory of Open Access Journals (Sweden)

    Mauro Pietribiasi

    Full Text Available The kinetics of protein transport to and from the vascular compartment play a major role in the determination of fluid balance and plasma refilling during hemodialysis (HD sessions. In this study we propose a whole-body mathematical model describing water and protein shifts across the capillary membrane during HD and compare its output to clinical data while evaluating the impact of choosing specific values for selected parameters.The model follows a two-compartment structure (vascular and interstitial space and is based on balance equations of protein mass and water volume in each compartment. The capillary membrane was described according to the three-pore theory. Two transport parameters, the fractional contribution of large pores (αLP and the total hydraulic conductivity (LpS of the capillary membrane, were estimated from patient data. Changes in the intensity and direction of individual fluid and solute flows through each part of the transport system were analyzed in relation to the choice of different values of small pores radius and fractional conductivity, lymphatic sensitivity to hydraulic pressure, and steady-state interstitial-to-plasma protein concentration ratio.The estimated values of LpS and αLP were respectively 10.0 ± 8.4 mL/min/mmHg (mean ± standard deviation and 0.062 ± 0.041. The model was able to predict with good accuracy the profiles of plasma volume and serum total protein concentration in most of the patients (average root-mean-square deviation < 2% of the measured value.The applied model provides a mechanistic interpretation of fluid transport processes induced by ultrafiltration during HD, using a minimum of tuned parameters and assumptions. The simulated values of individual flows through each kind of pore and lymphatic absorption rate yielded by the model may suggest answers to unsolved questions on the relative impact of these not-measurable quantities on total vascular refilling and fluid balance.

  13. Glider observations and modeling of sediment transport in Hurricane Sandy

    Science.gov (United States)

    Miles, Travis; Seroka, Greg; Kohut, Josh; Schofield, Oscar; Glenn, Scott

    2015-03-01

    Regional sediment resuspension and transport are examined as Hurricane Sandy made landfall on the Mid-Atlantic Bight (MAB) in October 2012. A Teledyne-Webb Slocum glider, equipped with a Nortek Aquadopp current profiler, was deployed on the continental shelf ahead of the storm, and is used to validate sediment transport routines coupled to the Regional Ocean Modeling System (ROMS). The glider was deployed on 25 October, 5 days before Sandy made landfall in southern New Jersey (NJ) and flew along the 40 m isobath south of the Hudson Shelf Valley. We used optical and acoustic backscatter to compare with two modeled size classes along the glider track, 0.1 and 0.4 mm sand, respectively. Observations and modeling revealed full water column resuspension for both size classes for over 24 h during peak waves and currents, with transport oriented along-shelf toward the southwest. Regional model predictions showed over 3 cm of sediment eroded on the northern portion of the NJ shelf where waves and currents were the highest. As the storm passed and winds reversed from onshore to offshore on the southern portion of the domain waves and subsequently orbital velocities necessary for resuspension were reduced leading to over 3 cm of deposition across the entire shelf, just north of Delaware Bay. This study highlights the utility of gliders as a new asset in support of the development and verification of regional sediment resuspension and transport models, particularly during large tropical and extratropical cyclones when in situ data sets are not readily available.

  14. Nearshore Tsunami Inundation Model Validation: Toward Sediment Transport Applications

    Science.gov (United States)

    Apotsos, Alex; Buckley, Mark; Gelfenbaum, Guy; Jaffe, Bruce; Vatvani, Deepak

    2011-01-01

    Model predictions from a numerical model, Delft3D, based on the nonlinear shallow water equations are compared with analytical results and laboratory observations from seven tsunami-like benchmark experiments, and with field observations from the 26 December 2004 Indian Ocean tsunami. The model accurately predicts the magnitude and timing of the measured water levels and flow velocities, as well as the magnitude of the maximum inundation distance and run-up, for both breaking and non-breaking waves. The shock-capturing numerical scheme employed describes well the total decrease in wave height due to breaking, but does not reproduce the observed shoaling near the break point. The maximum water levels observed onshore near Kuala Meurisi, Sumatra, following the 26 December 2004 tsunami are well predicted given the uncertainty in the model setup. The good agreement between the model predictions and the analytical results and observations demonstrates that the numerical solution and wetting and drying methods employed are appropriate for modeling tsunami inundation for breaking and non-breaking long waves. Extension of the model to include sediment transport may be appropriate for long, non-breaking tsunami waves. Using available sediment transport formulations, the sediment deposit thickness at Kuala Meurisi is predicted generally within a factor of 2.

  15. Thermodynamic Modeling of Gas Transport in Glassy Polymeric Membranes

    Science.gov (United States)

    Minelli, Matteo; Sarti, Giulio Cesare

    2017-01-01

    Solubility and permeability of gases in glassy polymers have been considered with the aim of illustrating the applicability of thermodynamically-based models for their description and prediction. The solubility isotherms are described by using the nonequilibrium lattice fluid (NELF) (model, already known to be appropriate for nonequilibrium glassy polymers, while the permeability isotherms are described through a general transport model in which diffusivity is the product of a purely kinetic factor, the mobility coefficient, and a thermodynamic factor. The latter is calculated from the NELF model and mobility is considered concentration-dependent through an exponential relationship containing two parameters only. The models are tested explicitly considering solubility and permeability data of various penetrants in three glassy polymers, PSf, PPh and 6FDA-6FpDA, selected as the reference for different behaviors. It is shown that the models are able to calculate the different behaviors observed, and in particular the permeability dependence on upstream pressure, both when it is decreasing as well as when it is increasing, with no need to invoke the onset of additional plasticization phenomena. The correlations found between polymer and penetrant properties with the two parameters of the mobility coefficient also lead to the predictive ability of the transport model. PMID:28825619

  16. Validation of Global Ozone Monitoring Experiment zone profiles and evaluation of stratospheric transport in a global chemistry transport model

    NARCIS (Netherlands)

    Laat, A.T.J.de; Landgraf, J.; Aben, I.; Hasekamp, O.; Bregman, B.

    2007-01-01

    This paper presents a validation of Global Ozone Monitoring Experiment (GOME) ozone (O3) profiles which are used to evaluate stratospheric transport in the chemistry transport model (CTM) Tracer Model version 5 (TM5) using a linearized stratospheric O3 chemistry scheme. A comparison of GOME O3

  17. Combined kinetic and transport modeling of radiofrequency current drive

    Energy Technology Data Exchange (ETDEWEB)

    Dumont, R.; Giruzzi, G. [Association Euratom-CEA, CEA/Cadarache, Dept. de Recherches sur la Fusion Controlee (DRFC), 13 - Saint-Paul-lez-Durance (France); Barbato, E. [Associazione EURATOM-ENEA sulla Fusione, Frascati (Italy)

    2000-07-01

    A numerical model for predictive simulations of radiofrequency current drive in magnetically confined plasmas is developed. It includes the minimum requirements for a self consistent description of such regimes, i.e., a 3-D ,kinetic equation for the electron distribution function, 1-D heat and current transport equations, and resonant coupling between velocity space and configuration space dynamics, through suitable wave propagation equations. The model finds its full application in predictive studies of complex current profile control scenarios in tokamaks, aiming at the establishment of internal transport barriers by the simultaneous use of various radiofrequency current drive methods. The basic properties of this non-linear numerical system are investigated and illustrated by simulations applied to reversed magnetic shear regimes obtained by Lower Hybrid and Electron Cyclotron current drive for parameters typical of the Tore Supra tokamak. (authors)

  18. Macroscopic Modeling of Transport Phenomena in Direct Methanol Fuel Cells

    DEFF Research Database (Denmark)

    Olesen, Anders Christian

    An increasing need for energy efficiency and high energy density has sparked a growing interest in direct methanol fuel cells for portable power applications. This type of fuel cell directly generates electricity from a fuel mixture consisting of methanol and water. Although this technology...... for studying their transport. In this PhD dissertation the macroscopic transport phenomena governing direct methanol fuel cell operation are analyzed, discussed and modeled using the two-fluid approach in the computational fluid dynamics framework of CFX 14. The overall objective of this work is to extend...... the present fundamental understanding of direct methanol fuel cell operation by developing a three-dimensional, two-phase, multi-component, non-isotherm mathematical model including detailed non-ideal thermodynamics, non-equilibrium phase change and non-equilibrium sorption-desorption of methanol and water...

  19. Modelling reactive transport in a phosphogypsum dump, Venezia, Italia

    Science.gov (United States)

    Calcara, Massimo; Borgia, Andrea; Cattaneo, Laura; Bartolo, Sergio; Clemente, Gianni; Glauco Amoroso, Carlo; Lo Re, Fabio; Tozzato, Elena

    2013-04-01

    We develop a reactive-transport porous media flow model for a phosphogypsum dump located on the intertidal deposits of the Venetian Lagoon: 1. we construct a complex conceptual and geologic model from field data using the GMS™ graphical user interface; 2. the geological model is mapped onto a rectangular MODFLOW grid; 3. using the TMT2 FORTRAN90 code we translate this grid into the MESH, INCON and GENER input files for the TOUGH2 series of codes; 4. we run TOUGH-REACT to model flow and reactive transport in the dump and the sediments below it. The model includes 3 different dump materials (phosphogypsum, bituminous and hazardous wastes) with the pores saturated by specific fluids. The sediments below the dump are formed by an intertidal sequence of calcareous sands and silts, in addition to clays and organic deposits, all of which are initially saturated with lagoon salty waters. The recharge rain-water dilutes the dump fluids. In turn, the percolates from the dump react with the underlying sediments and the sea water that saturates them. Simulation results have been compared with chemical sampled analyses. In fact, in spite of the simplicity of our model we are able to show how the pH becomes neutral at a short distance below the dump, a fact observed during aquifer monitoring. The spatial and temporal evolution of dissolution and precipitation reactions occur in our model much alike reality. Mobility of some elements, such as divalent iron, are reduced by specific and concurrent conditions of pH from near-neutrality to moderately high values and positive redox potential; opposite conditions favour mobility of potentially toxic metals such as Cr, As Cd and Pb. Vertical movement are predominant. Trend should be therefore heavily influenced by pH and Eh values. If conditions are favourable to mobility, concentration of these substances in the bottom strata could be high. However, simulation suggest that the sediments tend to reduce the transport potential of

  20. Anomalous solute transport in saturated porous media: Relating transport model parameters to electrical and nuclear magnetic resonance properties

    National Research Council Canada - National Science Library

    Swanson, Ryan D; Binley, Andrew; Keating, Kristina; France, Samantha; Osterman, Gordon; Day‐Lewis, Frederick D; Singha, Kamini

    2015-01-01

    The advection‐dispersion equation (ADE) fails to describe commonly observed non‐Fickian solute transport in saturated porous media, necessitating the use of other models such as the dual‐domain mass‐transfer (DDMT) model...

  1. Cuttings Transport Models and Experimental Visualization of Underbalanced Horizontal Drilling

    OpenAIRE

    Na Wei; YingFeng Meng; Gao Li; LiPing Wan; ZhaoYang Xu; XiaoFeng Xu; YuRui Zhang

    2013-01-01

    Aerated underbalanced horizontal drilling technology has become the focus of the drilling industry at home and abroad, and one of the engineering core issues is the horizontal borehole cleaning. Therefore, calculating the minimum injection volume of gas and liquid accurately is essential for the construction in aerated underbalanced horizontal drilling. This paper establishes a physical model of carrying cuttings and borehole cleaning in wellbore of horizontal well and a critical transport ma...

  2. Multiphysical modelling of fluid transport through osteo-articular media

    Directory of Open Access Journals (Sweden)

    Thibault Lemaire

    2010-03-01

    Full Text Available In this study, a multiphysical description of fluid transport through osteo-articular porous media is presented. Adapted from the model of Moyne and Murad, which is intended to describe clayey materials behaviour, this multiscale modelling allows for the derivation of the macroscopic response of the tissue from microscopical information. First the model is described. At the pore scale, electrohydrodynamics equations governing the electrolyte movement are coupled with local electrostatics (Gauss-Poisson equation, and ionic transport equations. Using a change of variables and an asymptotic expansion method, the macroscopic description is carried out. Results of this model are used to show the importance of couplings effects on the mechanotransduction of compact bone remodelling.Neste estudo uma descrição multifísica do transporte de fluidos em meios porosos osteo articulares é apresentada. Adaptado a partir do modelo de Moyne e Murad proposto para descrever o comportamento de materiais argilosos a modelagem multiescala permite a derivação da resposta macroscópica do tecido a partir da informação microscópica. Na primeira parte o modelo é apresentado. Na escala do poro as equações da eletro-hidrodinâmica governantes do movimento dos eletrolitos são acopladas com a eletrostática local (equação de Gauss-Poisson e as equações de transporte iônico. Usando uma mudança de variáveis e o método de expansão assintótica a derivação macroscópica é conduzida. Resultados do modelo proposto são usados para salientar a importância dos efeitos de acoplamento sobre a transdução mecânica da remodelagem de ossos compactados.

  3. Impact of transport model errors on the global and regional methane emissions estimated by inverse modelling

    NARCIS (Netherlands)

    Locatelli, R.; Bousquet, P.; Chevallier, F.; Fortems-Cheney, A.; Szopa, S.; Saunois, M.; Agusti-Panareda, A.; Bergmann, D.; Bian, H.; Cameron-Smith, P.; Chipperfield, M.P.; Gloor, E.; Houweling, S.; Kawa, S.R.; Krol, M.C.; Patra, P.K.; Prinn, R.G.; Rigby, M.; Saito, R.; Wilson, C.

    2013-01-01

    A modelling experiment has been conceived to assess the impact of transport model errors on methane emissions estimated in an atmospheric inversion system. Synthetic methane observations, obtained from 10 different model outputs from the international TransCom-CH4 model inter-comparison exercise,

  4. Modeling Nitrogen Fate and Transport at the Sediment-Water ...

    Science.gov (United States)

    Diffusive mass transfer at media interfaces exerts control on the fate and transport of pollutants originating from agricultural and urban landscapes and affects the con-ditions of water bodies. Diffusion is essentially a physical process affecting the distribution and fate of various environmental pollutants such as nutrients, pesticides, metals, PCBs, PAHs, etc. Environmental problems caused by excessive use of agricultural chemicals (e.g., pesticides and fertilizers) and improper discharge of industrial waste and fuel leaks are all influenced by the diffusive nature of pollutants in the environment. Eutrophication is one such environmental problem where the sediment-water interface exerts a significant physical and geochemical control on the eutrophic condition of the stressed water body. Exposure of streams and lakes to contaminated sediment is another common environmental problem whereby transport of the contaminant (PCBs, PAHs, and other organic contaminants) across the sediment water can increase the risk for exposure to the chemicals and pose a significant health hazard to aquatic life and human beings. This chapter presents analytical and numerical models describing fate and transport phenomena at the sediment-water interface in freshwater ecosystems, with the primary focus on nitrogen cycling and the applicability of the models to real-world environmental problems and challenges faced in their applications. The first model deals with nitrogen cycling

  5. How Open Data Shapes In Silico Transporter Modeling

    Directory of Open Access Journals (Sweden)

    Floriane Montanari

    2017-03-01

    Full Text Available Chemical compound bioactivity and related data are nowadays easily available from open data sources and the open medicinal chemistry literature for many transmembrane proteins. Computational ligand-based modeling of transporters has therefore experienced a shift from local (quantitative models to more global, qualitative, predictive models. As the size and heterogeneity of the data set rises, careful data curation becomes even more important. This includes, for example, not only a tailored cutoff setting for the generation of binary classes, but also the proper assessment of the applicability domain. Powerful machine learning algorithms (such as multi-label classification now allow the simultaneous prediction of multiple related targets. However, the more complex, the less interpretable these models will get. We emphasize that transmembrane transporters are very peculiar, some of which act as off-targets rather than as real drug targets. Thus, careful selection of the right modeling technique is important, as well as cautious interpretation of results. We hope that, as more and more data will become available, we will be able to ameliorate and specify our models, coming closer towards function elucidation and the development of safer medicine.

  6. Analysis of Intelligent Transportation Systems Using Model-Driven Simulations.

    Science.gov (United States)

    Fernández-Isabel, Alberto; Fuentes-Fernández, Rubén

    2015-06-15

    Intelligent Transportation Systems (ITSs) integrate information, sensor, control, and communication technologies to provide transport related services. Their users range from everyday commuters to policy makers and urban planners. Given the complexity of these systems and their environment, their study in real settings is frequently unfeasible. Simulations help to address this problem, but present their own issues: there can be unintended mistakes in the transition from models to code; their platforms frequently bias modeling; and it is difficult to compare works that use different models and tools. In order to overcome these problems, this paper proposes a framework for a model-driven development of these simulations. It is based on a specific modeling language that supports the integrated specification of the multiple facets of an ITS: people, their vehicles, and the external environment; and a network of sensors and actuators conveniently arranged and distributed that operates over them. The framework works with a model editor to generate specifications compliant with that language, and a code generator to produce code from them using platform specifications. There are also guidelines to help researchers in the application of this infrastructure. A case study on advanced management of traffic lights with cameras illustrates its use.

  7. Analysis of Intelligent Transportation Systems Using Model-Driven Simulations

    Directory of Open Access Journals (Sweden)

    Alberto Fernández-Isabel

    2015-06-01

    Full Text Available Intelligent Transportation Systems (ITSs integrate information, sensor, control, and communication technologies to provide transport related services. Their users range from everyday commuters to policy makers and urban planners. Given the complexity of these systems and their environment, their study in real settings is frequently unfeasible. Simulations help to address this problem, but present their own issues: there can be unintended mistakes in the transition from models to code; their platforms frequently bias modeling; and it is difficult to compare works that use different models and tools. In order to overcome these problems, this paper proposes a framework for a model-driven development of these simulations. It is based on a specific modeling language that supports the integrated specification of the multiple facets of an ITS: people, their vehicles, and the external environment; and a network of sensors and actuators conveniently arranged and distributed that operates over them. The framework works with a model editor to generate specifications compliant with that language, and a code generator to produce code from them using platform specifications. There are also guidelines to help researchers in the application of this infrastructure. A case study on advanced management of traffic lights with cameras illustrates its use.

  8. How Open Data Shapes In Silico Transporter Modeling.

    Science.gov (United States)

    Montanari, Floriane; Zdrazil, Barbara

    2017-03-07

    Chemical compound bioactivity and related data are nowadays easily available from open data sources and the open medicinal chemistry literature for many transmembrane proteins. Computational ligand-based modeling of transporters has therefore experienced a shift from local (quantitative) models to more global, qualitative, predictive models. As the size and heterogeneity of the data set rises, careful data curation becomes even more important. This includes, for example, not only a tailored cutoff setting for the generation of binary classes, but also the proper assessment of the applicability domain. Powerful machine learning algorithms (such as multi-label classification) now allow the simultaneous prediction of multiple related targets. However, the more complex, the less interpretable these models will get. We emphasize that transmembrane transporters are very peculiar, some of which act as off-targets rather than as real drug targets. Thus, careful selection of the right modeling technique is important, as well as cautious interpretation of results. We hope that, as more and more data will become available, we will be able to ameliorate and specify our models, coming closer towards function elucidation and the development of safer medicine.

  9. FinROSE - middle atmospheric chemistry transport model

    Energy Technology Data Exchange (ETDEWEB)

    Damski, J.; Thoelix, L.; Backman, L. (Research and Development, Finnish Meteorological Inst., Helsinki (FI)); Taalas, P. (Regional and Technical Cooperation for Development Dept. World Meteorological Organization, Geneve (CH)); Kulmala, M. (Helsinki Univ. (FI). Div. of Atmospheric Sciences)

    2007-07-01

    The development and performance of a three-dimensional global middle atmospheric chemistry transport model FinROSE is described. The FinROSE chemistry transport model includes a numerical scheme for stratospheric chemistry with parameterizations for heterogeneous processing on polar stratospheric clouds (PSC) and on liquid binary aerosols together with a parameterisation of large nitric acid trihydrate particles (i.e. NAT-rocks) and PSC sedimentation. The total number of trace species in the model is 34 and the total number of gas-phase reactions, photodissociation processes and heterogeneous reactions is about 150. The model is forced by external wind and temperature fields. The simulations are normally performed in a 5 deg x 10 deg (lat. x long.) grid from the surface up to around 0.1 hPa, with a vertical resolution of ca. 1.5 km in the stratosphere. Long-term simulations (40 to 50 years) have been done using winds and temperatures from ECMWF ERA40 analyses. The performance of the model in describing the stratospheric composition and chemistry is shown and evaluated in this paper. In general, the FinROSE results show a good comparison with measured total ozone. Also the timing, the depth and the deepening of the Antarctic ozone hole, and the responsible processes are captured well in the model simulations. (orig.)

  10. Analysis of Intelligent Transportation Systems Using Model-Driven Simulations

    Science.gov (United States)

    Fernández-Isabel, Alberto; Fuentes-Fernández, Rubén

    2015-01-01

    Intelligent Transportation Systems (ITSs) integrate information, sensor, control, and communication technologies to provide transport related services. Their users range from everyday commuters to policy makers and urban planners. Given the complexity of these systems and their environment, their study in real settings is frequently unfeasible. Simulations help to address this problem, but present their own issues: there can be unintended mistakes in the transition from models to code; their platforms frequently bias modeling; and it is difficult to compare works that use different models and tools. In order to overcome these problems, this paper proposes a framework for a model-driven development of these simulations. It is based on a specific modeling language that supports the integrated specification of the multiple facets of an ITS: people, their vehicles, and the external environment; and a network of sensors and actuators conveniently arranged and distributed that operates over them. The framework works with a model editor to generate specifications compliant with that language, and a code generator to produce code from them using platform specifications. There are also guidelines to help researchers in the application of this infrastructure. A case study on advanced management of traffic lights with cameras illustrates its use. PMID:26083232

  11. Comparison between Simulations and Transport Models for Imbalanced Magnetohydrodynamic Turbulence

    Science.gov (United States)

    Ng, C. S.; Dennis, T. J.

    2016-12-01

    One-dimensional (1D) turbulence transport models have long been applied rather successfully in modeling solar wind turbulence. However, direct comparison of such models with full simulations of solar wind turbulence is difficult due to the large scale of the system. As a first step in this direction, we present results from a series of 3D simulations of magnetohydrodynamic (MHD) turbulence based on reduced MHD equations. Alfven waves are launched from both ends of a long tube along the background uniform magnetic field so that turbulence develops due to collision between counter propagating Alfven waves in the interior region. Waves are launched randomly with specified correlation time Tc such that the length of the tube, L, is greater than (but of the same order of) VATc such that turbulence can fill most of the tube. While waves at both ends are launched with equal power, turbulence generated is imbalanced in general, with normalized cross-helicity gets close to -1 at one end and 1 at the other end. We will present our latest simulations at different resolutions with decreasing dissipation (resistivity and viscosity) levels and compare with model outputs from turbulence transport models regarding energy cascade, correlation length scales, etc., and discuss the validity of different assumptions employed in such models. This work is supported by a NASA grant NNX15AU61G.

  12. A coupled vegetation/sediment transport model for dryland environments

    Science.gov (United States)

    Mayaud, Jerome R.; Bailey, Richard M.; Wiggs, Giles F. S.

    2017-04-01

    Dryland regions are characterized by patchy vegetation, erodible surfaces, and erosive aeolian processes. Understanding how these constituent factors interact and shape landscape evolution is critical for managing potential environmental and anthropogenic impacts in drylands. However, modeling wind erosion on partially vegetated surfaces is a complex problem that has remained challenging for researchers. We present the new, coupled cellular automaton Vegetation and Sediment TrAnsport (ViSTA) model, which is designed to address fundamental questions about the development of arid and semiarid landscapes in a spatially explicit way. The technical aspects of the ViSTA model are described, including a new method for directly imposing oblique wind and transport directions onto a cell-based domain. Verification tests for the model are reported, including stable state solutions, the impact of drought and fire stress, wake flow dynamics, temporal scaling issues, and the impact of feedbacks between sediment movement and vegetation growth on landscape morphology. The model is then used to simulate an equilibrium nebkha dune field, and the resultant bed forms are shown to have very similar size and spacing characteristics to nebkhas observed in the Skeleton Coast, Namibia. The ViSTA model is a versatile geomorphological tool that could be used to predict threshold-related transitions in a range of dryland ecogeomorphic systems.

  13. Impact of mineralogical heterogeneity on reactive transport modelling

    Science.gov (United States)

    Liu, Min; Shabaninejad, Mehdi; Mostaghimi, Peyman

    2017-07-01

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

  14. Fluid transport and ion fluxes in mammalian kidney proximal tubule: a model analysis of isotonic transport

    DEFF Research Database (Denmark)

    Larsen, Erik Hviid; Møbjerg, N.; Sørensen, J. N.

    2006-01-01

    'blocking' of apical water channels and in 'aquaporin-null' simulation. Reduced rate of volume reabsorption in AQP(-/-) mice would also require decreased apical sodium permeability. Paracellular convection accounts for approx. 36% of the net Na+ absorption, and the model epithelium accomplishes uphill water...... simulates major physiological features of proximal tubule, including significantly lower water permeability of the AQP1-null preparation, and a ratio of net sodium uptake and oxygen consumption exceeding that predicted from stoichiometry of the Na+/K+-pump. Physical properties of interspace basement......Aim: By mathematical modelling, we analyse conditions for near-isotonic and isotonic transport by mammalian kidney proximal tubule. Methods: The model comprises compliant lateral intercellular space (lis) and cells, and infinitely large luminal and peritubular compartments with diffusible species...

  15. Fluid transport and ion fluxes in mammalian kidney proximal tubule: a model analysis of isotonic transport

    DEFF Research Database (Denmark)

    Larsen, E.H.; Møbjerg, N.; Sørensen, Jens Nørkær

    2006-01-01

    'blocking' of apical water channels and in 'aquaporin-null' simulation. Reduced rate of volume reabsorption in AQP(-/-) mice would also require decreased apical sodium permeability. Paracellular convection accounts for approx. 36% of the net Na+ absorption, and the model epithelium accomplishes uphill water...... simulates major physiological features of proximal tubule, including significantly lower water permeability of the AQP1-null preparation, and a ratio of net sodium uptake and oxygen consumption exceeding that predicted from stoichiometry of the Na+/K+-pump. Physical properties of interspace basement......Aim: By mathematical modelling, we analyse conditions for near-isotonic and isotonic transport by mammalian kidney proximal tubule. Methods: The model comprises compliant lateral intercellular space (lis) and cells, and infinitely large luminal and peritubular compartments with diffusible species...

  16. Engineered Barrier System Degradation, Flow, and Transport Process Model Report

    Energy Technology Data Exchange (ETDEWEB)

    E.L. Hardin

    2000-07-17

    The Engineered Barrier System Degradation, Flow, and Transport Process Model Report (EBS PMR) is one of nine PMRs supporting the Total System Performance Assessment (TSPA) being developed by the Yucca Mountain Project for the Site Recommendation Report (SRR). The EBS PMR summarizes the development and abstraction of models for processes that govern the evolution of conditions within the emplacement drifts of a potential high-level nuclear waste repository at Yucca Mountain, Nye County, Nevada. Details of these individual models are documented in 23 supporting Analysis/Model Reports (AMRs). Nineteen of these AMRs are for process models, and the remaining 4 describe the abstraction of results for application in TSPA. The process models themselves cluster around four major topics: ''Water Distribution and Removal Model, Physical and Chemical Environment Model, Radionuclide Transport Model, and Multiscale Thermohydrologic Model''. One AMR (Engineered Barrier System-Features, Events, and Processes/Degradation Modes Analysis) summarizes the formal screening analysis used to select the Features, Events, and Processes (FEPs) included in TSPA and those excluded from further consideration. Performance of a potential Yucca Mountain high-level radioactive waste repository depends on both the natural barrier system (NBS) and the engineered barrier system (EBS) and on their interactions. Although the waste packages are generally considered as components of the EBS, the EBS as defined in the EBS PMR includes all engineered components outside the waste packages. The principal function of the EBS is to complement the geologic system in limiting the amount of water contacting nuclear waste. A number of alternatives were considered by the Project for different EBS designs that could provide better performance than the design analyzed for the Viability Assessment. The design concept selected was Enhanced Design Alternative II (EDA II).

  17. Bedrock hydrogeochemistry Forsmark. Site descriptive modelling SDM-Site Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Laaksoharju, Marcus (Geopoint AB, Sollentuna (Sweden)); Smellie, John (Conterra AB, Partille (Sweden)); Tullborg, Eva-Lena (Terralogica, Graabo (Sweden)); Gimeno, Maria (Univ. of Zaragoza, Zaragoza (Spain)); Hallbeck, Lotta (Microbial Analytics, Goeteborg (Sweden)); Molinero, Jorge (Amphos XXI Consulting S.L., Barcelona (Spain)); Waber, Nick (Univ. of Bern, Bern (Switzerland))

    2008-12-15

    The overall objectives of the hydrogeochemical site description for Forsmark are to establish a detailed understanding of the hydrogeochemical conditions at the site, and to use this understanding to develop models that address the needs identified by the safety assessment groups during the site investigation phase. Issues of concern to safety assessment are radionuclide transport and technical barrier behaviour, both of which are dependent on the chemistry of groundwater and porewater and their evolution with time. The specific aims of the hydrogeochemical work were: To document the hydrogeochemistry at the Forsmark site with focus on the development of conceptual models to describe and visualise the site. To provide relevant parameter values to be used for safety assessment calculations. To provide the hydrogeochemical basis for the modelling work by other teams, in particular hydrogeology. To take account of the feedback from the SR-Can safety assessment work that bears relevance to the hydrogeochemical modelling work. The work has involved the development of descriptive and mathematical models for groundwaters in relation to rock domains, fracture domains and deformation zones. In this report, the groundwaters have been interpreted in relation to their origin, evolution and composition, which require close integration with geological, climatological and hydrogeological information. Past climate changes are one of the major driving forces for long-term hydrogeochemical changes (hundreds to thousands of years) and are, therefore, of fundamental importance for understanding the palaeohydrogeological, palaeohydrogeochemical and present evolution of groundwater in the Fennoscandian crystalline bedrock. In contrast, redox buffer capacity of the bedrock will minimise the effects on changes in alkalinity and redox at repository depths, therefore limiting the variations in pH and Eh significantly, regardless of major changes in groundwater composition. There is

  18. Jet propagation within a Linearized Boltzmann Transport model

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Tan; He, Yayun [Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079 (China); Wang, Xin-Nian [Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079 (China); Nuclear Science Division, Mailstop 70R0319, Lawrence Berkeley National Laboratory, Berkeley, CA 94740 (United States); Zhu, Yan [Departamento de Física de Partículas and IGFAE, Universidade de Santiago de Compostela, E-15706 Santiago de Compostela, Galicia (Spain)

    2014-12-15

    A Linearized Boltzmann Transport (LBT) model has been developed for the study of parton propagation inside quark–gluon plasma. Both leading and thermal recoiled partons are tracked in order to include the effect of jet-induced medium excitation. In this talk, we present a study within the LBT model in which we implement the complete set of elastic parton scattering processes. We investigate elastic parton energy loss and their energy and length dependence. We further investigate energy loss and transverse shape of reconstructed jets. Contributions from the recoiled thermal partons and jet-induced medium excitations are found to have significant influences on the jet energy loss and transverse profile.

  19. Process-based modeling of tsunami inundation and sediment transport

    Science.gov (United States)

    Apotsos, A.; Gelfenbaum, G.; Jaffe, B.

    2011-01-01

    The infrequent and unpredictable nature of tsunamis precludes the use of field experiments to measure the hydrodynamic and sediment transport processes that occur. Instead, these processes are often approximated from laboratory, numerical, and theoretical studies or inferred from observations of the resultant sediment deposits. Here Delft3D, a three-dimensional numerical model, is used to simulate the inundation and sediment transport of a tsunami similar in magnitude to the 26 December 2004 Indian Ocean tsunami over one measured and three idealized morphologies. The model is first shown to match well the observations taken at Kuala Meurisi, Sumatra, and then used to examine in detail the processes that occur during the tsunami. The model predicts that at a given cross-shore location the onshore flow accelerates rapidly to a maximum as the wavefront passes, and then gradually decelerates before reversing direction and flowing offshore. The onshore flow does not tend to zero everywhere at maximum inundation, but instead flow reversal occurs near the shoreline even as the wavefront continues to inundate landward. While some sediment is eroded by the passing wavefront, the suspension of sandy sediment is dominated by the long-duration, high-velocity backwash that occurs along the beach face and offshore of the shoreline. Some of the sediment suspended during backwash is advected shoreward by the subsequent wave, creating large spatial gradients in the suspended sediment concentrations, which may not be in equilibrium with the local hydrodynamics. The inundation and transport of sediment during a tsunami can be affected by complexities in the morphological profile and interactions between multiple waves, and many of the hydrodynamic and sediment transport processes predicted here are similar to analogous processes previously observed in the swash zone. Copyright 2011 by the American Geophysical Union.

  20. Transport Studies and Modeling in PEM Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Mittelsteadt, Cortney K. [Giner, Inc., Auburndale, MA (United States); Xu, Hui [Giner, Inc., Auburndale, MA (United States); Brawn, Shelly [Giner, Inc., Auburndale, MA (United States)

    2014-07-30

    This project’s aim was to develop fuel cell components (i.e. membranes, gas-diffusion media (GDM), bipolar plates and flow fields) that possess specific properties (i.e. water transport and conductivity). A computational fluid dynamics model was developed to elucidate the effect of certain parameters on these specific properties. Ultimately, the model will be used to determine sensitivity of fuel cell performance to component properties to determine limiting components and to guide research. We have successfully reached our objectives and achieved most of the milestones of this project. We have designed and synthesized a variety of hydrocarbon block polymer membranes with lower equivalent weight, structure, chemistry, phase separation and process conditions. These membranes provide a broad selection with optimized water transport properties. We have also designed and constructed a variety of devices that are capable of accurately measuring the water transport properties (water uptake, water diffusivity and electro-osmatic drag) of these membranes. These transport properties are correlated to the membranes’ structures derived from X-ray and microscopy techniques to determine the structure-property relationship. We successfully integrated hydrocarbon membrane MEAs with a current distribution board (CBD) to study the impact of hydrocarbon membrane on water transport in fuel cells. We have designed and fabricated various GDM with varying substrate, diffusivity and micro-porous layers (MPL) and characterized their pore structure, tortuosity and hydrophobicity. We have derived a universal chart (MacMullin number as function of wet proofing and porosity) that can be used to characterize various GDM. The abovementioned GDMs have been evaluated in operating fuel cells; their performance is correlated to various pore structure, tortuosity and hydrophobicity of the GDM. Unfortunately, determining a universal relationship between the MacMullin number and these properties

  1. Predicting subsurface uranium transport: Mechanistic modeling constrained by experimental data

    Science.gov (United States)

    Ottman, Michael; Schenkeveld, Walter D. C.; Kraemer, Stephan

    2017-04-01

    Depleted uranium (DU) munitions and their widespread use throughout conflict zones around the world pose a persistent health threat to the inhabitants of those areas long after the conclusion of active combat. However, little emphasis has been put on developing a comprehensive, quantitative tool for use in remediation and hazard avoidance planning in a wide range of environments. In this context, we report experimental data on U interaction with soils and sediments. Here, we strive to improve existing risk assessment modeling paradigms by incorporating a variety of experimental data into a mechanistic U transport model for subsurface environments. 20 different soils and sediments from a variety of environments were chosen to represent a range of geochemical parameters that are relevant to U transport. The parameters included pH, organic matter content, CaCO3, Fe content and speciation, and clay content. pH ranged from 3 to 10, organic matter content from 6 to 120 g kg-1, CaCO3 from 0 to 700 g kg-1, amorphous Fe content from 0.3 to 6 g kg-1 and clay content from 4 to 580 g kg-1. Sorption experiments were then performed, and linear isotherms were constructed. Sorption experiment results show that among separate sets of sediments and soils, there is an inverse correlation between both soil pH and CaCO¬3 concentration relative to U sorptive affinity. The geological materials with the highest and lowest sorptive affinities for U differed in CaCO3 and organic matter concentrations, as well as clay content and pH. In a further step, we are testing if transport behavior in saturated porous media can be predicted based on adsorption isotherms and generic geochemical parameters, and comparing these modeling predictions with the results from column experiments. The comparison of these two data sets will examine if U transport can be effectively predicted from reactive transport modeling that incorporates the generic geochemical parameters. This work will serve to show

  2. Early warning of freshwater salinization due to upward brine displacement by species transport simulations combined with a hydrochemical genesis model

    Science.gov (United States)

    Langer, Maria; Kühn, Michael

    2016-04-01

    Shallow groundwater resources could be possibly affected by intruding brines, which are displaced along hydraulically conductive faults as result of subsurface activities like CO2 injection. To avoid salinization of potable freshwater aquifers an early detection of intruding saline water is necessary, especially in regions where an initial geogenic salinization already exists. Our study is based on work of Tillner et al. [1] and Langer et al. [2] who investigated the influence of permeable fault systems on brine displacement for the prospective storage site Beeskow-Birkholz in the Northeast German Basin. With a 3D regional scale model considering the deep groundwater system, they demonstrated that the existence of hydraulically conductive faults is not necessarily an exclusion criterion for potential injection sites, because salinization of shallower aquifers strongly depends on the effective damage zone volume, the initial salinity distribution and overlying reservoirs [2], while permeability of fault zones does not influence salinization of shallower aquifers significantly [1]. Here we extracted a 2D cross section regarding the upper 220 m of the study area mainly represented by shallow freshwater aquifers, but also considering an initial geogenic salinization [3]. We took flow rates of the intruding brines from the previous studies [2] and implemented species transport simulations with the program code SHEMAT [4]. Results are investigated and interpreted with the hydrochemical genesis model GEBAH [5] which has been already applied as early warning of saltwater intrusions into freshwater aquifers and surface water [6]. GEBAH allows a categorization of groundwater by the ion ratios of the dissolved components and offers a first indicative determination for an existence and the intensity of saline water intrusion in shallow groundwater aquifer, independent of the concentration of the solution. With our model we investigated the migration of saline water through a

  3. An Eulerian transport/transformation/removal model for SO2 and sulfate. I - Model development. II - Model calculation of SO(x) transport in the eastern United States

    Science.gov (United States)

    Carmichael, G. R.; Peters, L. K.

    1984-01-01

    A three-dimensional, time dependent Eulerian atmospheric SO2 and sulfate transport/transformation/removal model is described and applied to the eastern U.S. The model was developed in anticipation of increased input to the atmospheric sulfur content by coal-burning power plants in the near future and is intended as an aid in identifying sources of SO2. The Eulerian transport model incorporates functions for chemical transformations, dry deposition, spatial topographical variations, spatial and temporal variations of mixing layer heights, the wind field, eddy diffusivities, deposition velocities, and temperature and water concentration profiles. Attention is also given to the SO2 photochemical oxidation mechanism and rates. Results from a 72-hr simulation of SO(x) transport over the eastern U.S., using actual 1974 meteorological data, illustrate the model's capability to depict interactions between emissions, transport, chemistry and removal. Concentration distributions are demonstrated to have significant spatial and temporal variations.

  4. Using transportation demand models to assess regional noise exposure

    Science.gov (United States)

    Kaliski, Kenneth

    2005-09-01

    In the United States, most metropolitan areas run some type of transportation demand model to estimate regional travel patterns, and, to some extent, air pollution. The more advanced of these models accurately represent the geographic contours of the roadways (in contrast to the older straight-line node and link models). This allows an almost seamless integration of these new transportation demand models into noise prediction models. Combined with the locations of individual homes from a separate E911 database, we can readily make estimates of the noise exposure of populations over large areas. In this paper, the regional traffic noise exposure of residences of Chittenden County, VT is estimated and mapped. It was found that 30% of the residences are exposed to noise levels exceeding the WHO sleep disturbance level of 45 dB LAeq(8) and 20% of residences are exposed to levels exceeding the WHO ``serious annoyance'' level of 55 dB LAeq(16). Maps show noise contours as well as individual homes color coded based on relative day and night noise exposure levels. Measured sound level data are given for particular locations to validate the predictions.

  5. Particle transport model sensitivity on wave-induced processes

    Science.gov (United States)

    Staneva, Joanna; Ricker, Marcel; Krüger, Oliver; Breivik, Oyvind; Stanev, Emil; Schrum, Corinna

    2017-04-01

    Different effects of wind waves on the hydrodynamics in the North Sea are investigated using a coupled wave (WAM) and circulation (NEMO) model system. The terms accounting for the wave-current interaction are: the Stokes-Coriolis force, the sea-state dependent momentum and energy flux. The role of the different Stokes drift parameterizations is investigated using a particle-drift model. Those particles can be considered as simple representations of either oil fractions, or fish larvae. In the ocean circulation models the momentum flux from the atmosphere, which is related to the wind speed, is passed directly to the ocean and this is controlled by the drag coefficient. However, in the real ocean, the waves play also the role of a reservoir for momentum and energy because different amounts of the momentum flux from the atmosphere is taken up by the waves. In the coupled model system the momentum transferred into the ocean model is estimated as the fraction of the total flux that goes directly to the currents plus the momentum lost from wave dissipation. Additionally, we demonstrate that the wave-induced Stokes-Coriolis force leads to a deflection of the current. During the extreme events the Stokes velocity is comparable in magnitude to the current velocity. The resulting wave-induced drift is crucial for the transport of particles in the upper ocean. The performed sensitivity analyses demonstrate that the model skill depends on the chosen processes. The results are validated using surface drifters, ADCP, HF radar data and other in-situ measurements in different regions of the North Sea with a focus on the coastal areas. The using of a coupled model system reveals that the newly introduced wave effects are important for the drift-model performance, especially during extremes. Those effects cannot be neglected by search and rescue, oil-spill, transport of biological material, or larva drift modelling.

  6. Building 235-F Goldsim Fate And Transport Model

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, G. A.; Phifer, M. A.

    2012-09-14

    Savannah River National Laboratory (SRNL) personnel, at the request of Area Completion Projects (ACP), evaluated In-Situ Disposal (ISD) alternatives that are under consideration for deactivation and decommissioning (D&D) of Building 235-F and the Building 294-2F Sand Filter. SRNL personnel developed and used a GoldSim fate and transport model, which is consistent with Musall 2012, to evaluate relative to groundwater protection, ISD alternatives that involve either source removal and/or the grouting of portions or all of 235-F. This evaluation was conducted through the development and use of a Building 235-F GoldSim fate and transport model. The model simulates contaminant release from four 235-F process areas and the 294-2F Sand Filter. In addition, it simulates the fate and transport through the vadose zone, the Upper Three Runs (UTR) aquifer, and the Upper Three Runs (UTR) creek. The model is designed as a stochastic model, and as such it can provide both deterministic and stochastic (probabilistic) results. The results show that the median radium activity concentrations exceed the 5 ?Ci/L radium MCL at the edge of the building for all ISD alternatives after 10,000 years, except those with a sufficient amount of inventory removed. A very interesting result was that grouting was shown to basically have minimal effect on the radium activity concentration. During the first 1,000 years grouting may have some small positive benefit relative to radium, however after that it may have a slightly deleterious effect. The Pb-210 results, relative to its 0.06 ?Ci/L PRG, are essentially identical to the radium results, but the Pb-210 results exhibit a lesser degree of exceedance. In summary, some level of inventory removal will be required to ensure that groundwater standards are met.

  7. Energy Models for One-Carrier Transport in Semiconductor Devices

    Science.gov (United States)

    Jerome, Joseph W.; Shu, Chi-Wang

    1991-01-01

    Moment models of carrier transport, derived from the Boltzmann equation, made possible the simulation of certain key effects through such realistic assumptions as energy dependent mobility functions. This type of global dependence permits the observation of velocity overshoot in the vicinity of device junctions, not discerned via classical drift-diffusion models, which are primarily local in nature. It was found that a critical role is played in the hydrodynamic model by the heat conduction term. When ignored, the overshoot is inappropriately damped. When the standard choice of the Wiedemann-Franz law is made for the conductivity, spurious overshoot is observed. Agreement with Monte-Carlo simulation in this regime required empirical modification of this law, or nonstandard choices. Simulations of the hydrodynamic model in one and two dimensions, as well as simulations of a newly developed energy model, the RT model, are presented. The RT model, intermediate between the hydrodynamic and drift-diffusion model, was developed to eliminate the parabolic energy band and Maxwellian distribution assumptions, and to reduce the spurious overshoot with physically consistent assumptions. The algorithms employed for both models are the essentially non-oscillatory shock capturing algorithms. Some mathematical results are presented and contrasted with the highly developed state of the drift-diffusion model.

  8. Fractal continuum model for tracer transport in a porous medium.

    Science.gov (United States)

    Herrera-Hernández, E C; Coronado, M; Hernández-Coronado, H

    2013-12-01

    A model based on the fractal continuum approach is proposed to describe tracer transport in fractal porous media. The original approach has been extended to treat tracer transport and to include systems with radial and uniform flow, which are cases of interest in geoscience. The models involve advection due to the fluid motion in the fractal continuum and dispersion whose mathematical expression is taken from percolation theory. The resulting advective-dispersive equations are numerically solved for continuous and for pulse tracer injection. The tracer profile and the tracer breakthrough curve are evaluated and analyzed in terms of the fractal parameters. It has been found in this work that anomalous transport frequently appears, and a condition on the fractal parameter values to predict when sub- or superdiffusion might be expected has been obtained. The fingerprints of fractality on the tracer breakthrough curve in the explored parameter window consist of an early tracer breakthrough and long tail curves for the spherical and uniform flow cases, and symmetric short tailed curves for the radial flow case.

  9. A heterogeneous model for gas transport in carbon molecular sieves.

    Science.gov (United States)

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

    2005-01-18

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

  10. Modelling of Sediment Transport in Beris Fishery Port

    Directory of Open Access Journals (Sweden)

    Samira Ardani

    2015-06-01

    Full Text Available In this paper, the large amount of sedimentation and the resultant shoreline advancements at the breakwaters of Beris Fishery Port are studied. A series of numerical modeling of waves, sediment transport, and shoreline changes were conducted to predict the complicated equilibrium shoreline. The outputs show that the nearshore directions of wave components are not perpendicular to the coast which reveals the existence of longshore currents and consequently sediment transport along the bay. Considering the dynamic equilibrium condition of the bay, the effect of the existing sediment resources in the studied area is also investigated. The study also shows that in spite of the change of the diffraction point of Beris Bay after the construction of the fishery port, the bay is approaching its dynamic equilibrium condition, and the shoreline advancement behind secondary breakwater will stop before blocking the entrance of the port. The probable solutions to overcome the sedimentation problem at the main breakwater are also discussed.

  11. Land transportation model for supply chain manufacturing industries

    Science.gov (United States)

    Kurniawan, Fajar

    2017-12-01

    Supply chain is a system that integrates production, inventory, distribution and information processes for increasing productivity and minimize costs. Transportation is an important part of the supply chain system, especially for supporting the material distribution process, work in process products and final products. In fact, Jakarta as the distribution center of manufacturing industries for the industrial area. Transportation system has a large influences on the implementation of supply chain process efficiency. The main problem faced in Jakarta is traffic jam that will affect on the time of distribution. Based on the system dynamic model, there are several scenarios that can provide solutions to minimize timing of distribution that will effect on the cost such as the construction of ports approaching industrial areas other than Tanjung Priok, widening road facilities, development of railways system, and the development of distribution center.

  12. Kinematic Models for Soil Moisture and Solute Transport

    Science.gov (United States)

    Charbeneau, Randall J.

    1984-06-01

    The kinematic theory of soil moisture and solute transport in the vertical direction for unsaturated groundwater recharge is considered. The general theory of kinematic models is reviewed and applied for an isolated wetting event wherein the soil starts at and eventually drains to field capacity. Analytical expressions are developed for the water content and moisture flux as a function of depth and time. The approach is extended for an arbitrary sequence of surface flux or water content boundary conditions. The transport of a solute with a general nonlinear sorption isotherm is also considered. It is shown that for the general isotherm the vertical displacement of a solute isochore during an arbitrary wetting sequence depends only on the total depth of water infiltrated and not on how the infiltration rate varies with time.

  13. Systematic evaluation of atmospheric chemistry-transport model CHIMERE

    Science.gov (United States)

    Khvorostyanov, Dmitry; Menut, Laurent; Mailler, Sylvain; Siour, Guillaume; Couvidat, Florian; Bessagnet, Bertrand; Turquety, Solene

    2017-04-01

    Regional-scale atmospheric chemistry-transport models (CTM) are used to develop air quality regulatory measures, to support environmentally sensitive decisions in the industry, and to address variety of scientific questions involving the atmospheric composition. Model performance evaluation with measurement data is critical to understand their limits and the degree of confidence in model results. CHIMERE CTM (http://www.lmd.polytechnique.fr/chimere/) is a French national tool for operational forecast and decision support and is widely used in the international research community in various areas of atmospheric chemistry and physics, climate, and environment (http://www.lmd.polytechnique.fr/chimere/CW-articles.php). This work presents the model evaluation framework applied systematically to the new CHIMERE CTM versions in the course of the continuous model development. The framework uses three of the four CTM evaluation types identified by the Environmental Protection Agency (EPA) and the American Meteorological Society (AMS): operational, diagnostic, and dynamic. It allows to compare the overall model performance in subsequent model versions (operational evaluation), identify specific processes and/or model inputs that could be improved (diagnostic evaluation), and test the model sensitivity to the changes in air quality, such as emission reductions and meteorological events (dynamic evaluation). The observation datasets currently used for the evaluation are: EMEP (surface concentrations), AERONET (optical depths), and WOUDC (ozone sounding profiles). The framework is implemented as an automated processing chain and allows interactive exploration of the results via a web interface.

  14. Surface transportation security and reliability information system model deployment : iFlorida final concept of operations

    Science.gov (United States)

    2003-09-03

    FDOT began design of a Surface Transportation Security and Reliability Information System Model Deployment in May 2003. This model deployment focuses on enhancing the security and reliability of the surface transportation system through the widesprea...

  15. Integrated land-use and transport modelling using OTP to determine lowest cost trips

    CSIR Research Space (South Africa)

    Van Heerden, Q

    2015-10-01

    Full Text Available This presentation discusses the link between economic infrastructure, that includes transport, and social infrastructure that includes social well-being and the basic necessities of people. It shows how transport models and urban models influence...

  16. Modeling of a Small Transportation Company's Start-Up with Limited Data during Economic Recession

    National Research Council Canada - National Science Library

    Xiaoping Fang; Jake Ansell; Weiya Chen

    2013-01-01

    .... Since the transportation market is segmented by business type and transportation distance, a polynomial model and logistic curve model were constructed to forecast the growth trend of each segmented...

  17. Optimization of atmospheric transport models on HPC platforms

    Science.gov (United States)

    de la Cruz, Raúl; Folch, Arnau; Farré, Pau; Cabezas, Javier; Navarro, Nacho; Cela, José María

    2016-12-01

    The performance and scalability of atmospheric transport models on high performance computing environments is often far from optimal for multiple reasons including, for example, sequential input and output, synchronous communications, work unbalance, memory access latency or lack of task overlapping. We investigate how different software optimizations and porting to non general-purpose hardware architectures improve code scalability and execution times considering, as an example, the FALL3D volcanic ash transport model. To this purpose, we implement the FALL3D model equations in the WARIS framework, a software designed from scratch to solve in a parallel and efficient way different geoscience problems on a wide variety of architectures. In addition, we consider further improvements in WARIS such as hybrid MPI-OMP parallelization, spatial blocking, auto-tuning and thread affinity. Considering all these aspects together, the FALL3D execution times for a realistic test case running on general-purpose cluster architectures (Intel Sandy Bridge) decrease by a factor between 7 and 40 depending on the grid resolution. Finally, we port the application to Intel Xeon Phi (MIC) and NVIDIA GPUs (CUDA) accelerator-based architectures and compare performance, cost and power consumption on all the architectures. Implications on time-constrained operational model configurations are discussed.

  18. Multi-shell transport model for L-H transition

    Science.gov (United States)

    Berionni, V.; Morel, P.; Gürcan, Ö. D.

    2017-12-01

    A coupled model of transport, turbulence, and mesoscale flows is proposed, including turbulence spreading. The model consists of transport equations for plasma density and pressure coupled to a shell model of drift wave turbulence, which incorporates coupling to mesoscale flows via disparate scale interactions. The model can describe the turbulent cascade and its dynamical interplay with zonal and mean shear flows as well as the profile evolution (including the profiles of turbulence intensity itself) due to these self-consistent turbulent fluxes. This simple system of equations is shown to capture the low to high confinement (L-H) transition. It is also observed that as the heating is increased, the system goes through an intermediate phase that displays oscillations between zonal flows and turbulence. The transition towards the H mode, which is characterized by the presence of a strong mean shear flow at the edge, is triggered by the mesoscale dynamics due to the action of zonal flows, with turbulence spreading playing an important role in the H to L back transition.

  19. Water Quality and Hydrogeochemical Characteristics of Surface Water and Groundwaters in Aksu (Isparta Plain

    Directory of Open Access Journals (Sweden)

    Şehnaz Şener

    2015-12-01

    Full Text Available In this study, geological, hydrological, hydrogeological, hydrogeochemical characteristics of the Aksu (Isparta plain were investigated. In addition, determination of the water quality and availability in current status besides groundwater dynamics were aimed in the scope of work. The study area is located in the southwest Turkey, and lithological units belonging to Beydaglari autochthonous and Antalya nappes are observed. The most important surface water and groundwater reservoirs are Aksu river and alluvial-karst aquifers, respectively. Hydrogeochemical characteristics and quality of the water are important because water is used as drinking water and irrigation water in the plain. For this purpose, in situ measurements and chemical analyzes were carried out in the period of May-2013 on water resources. According to the obtained results, water resources is Mg-HCO3, Ca-HCO3, and Mg-Ca-HCO3 facies. According to the Water Pollution Control Regulation, all surface and groundwaters are determined in 4th water quality class in terms of sulfur owing to water-rock interaction. The assessment of the usage properties of the waters indicate that water sources is suitable for drinking and irrigation water usage in generally.

  20. Hydrogeochemical and spectroscopic studies of radioactive materials in Ayrakan and Cheshmeh Shotori areas, northeastern Isfahan province

    Directory of Open Access Journals (Sweden)

    Mostafa Esmaeili Vardanjani

    2011-11-01

    Full Text Available Groundwaters hydrochemistry of Ayrakan and Cheshmeh Shotori areas and geochemistry of rare earth elements, indicate Ayrakan alkali granite as the origin of uranium and other dissolved elements in groundwaters of these areas. Geochemical and hydrogeochemical studies as well as the trend of uranium and thorium transition and mobility in aqueous environments of these areas indicate uranium adsorption by iron hydroxide (goethite as the deterrent agent against uranium transition and mobility from depth to surface. Gamma-ray spectroscopic study of sediments from Cheshmeh Shotori area by HPGe detector indicates the presence of 226Ra in high contents and as the radioactive nuclide that is the reason for high activity of these sediments. Production of 226Ra from 238U decay, shorter half-life of 226Ra compared to 238U, radium transition by groundwaters from depth to surface as well as hydrogeochemical evidences, all suggest the possibility of existence of hidden uranium deposit and uranium mineralization in depth and the distance between Ayrakan and Cheshmeh Shotori areas.

  1. Transportation Sector Model of the National Energy Modeling System. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-01-01

    This report documents the objectives, analytical approach and development of the National Energy Modeling System (NEMS) Transportation Model (TRAN). The report catalogues and describes the model assumptions, computational methodology, parameter estimation techniques, model source code, and forecast results generated by the model. The NEMS Transportation Model comprises a series of semi-independent models which address different aspects of the transportation sector. The primary purpose of this model is to provide mid-term forecasts of transportation energy demand by fuel type including, but not limited to, motor gasoline, distillate, jet fuel, and alternative fuels (such as CNG) not commonly associated with transportation. The current NEMS forecast horizon extends to the year 2010 and uses 1990 as the base year. Forecasts are generated through the separate consideration of energy consumption within the various modes of transport, including: private and fleet light-duty vehicles; aircraft; marine, rail, and truck freight; and various modes with minor overall impacts, such as mass transit and recreational boating. This approach is useful in assessing the impacts of policy initiatives, legislative mandates which affect individual modes of travel, and technological developments. The model also provides forecasts of selected intermediate values which are generated in order to determine energy consumption. These elements include estimates of passenger travel demand by automobile, air, or mass transit; estimates of the efficiency with which that demand is met; projections of vehicle stocks and the penetration of new technologies; and estimates of the demand for freight transport which are linked to forecasts of industrial output. Following the estimation of energy demand, TRAN produces forecasts of vehicular emissions of the following pollutants by source: oxides of sulfur, oxides of nitrogen, total carbon, carbon dioxide, carbon monoxide, and volatile organic compounds.

  2. MODELING TRITIUM TRANSPORT, DEPOSITION AND RE-EMISSION

    Energy Technology Data Exchange (ETDEWEB)

    Viner, B.

    2012-04-03

    The atmospheric release of tritium oxide (HTO) potentially impacts human health, typically through inhalation or absorption. Due to HTO's similarity to water, vegetation will absorb HTO by solution in the leaf water and then re-emit it, creating a number of secondary sources of HTO. Currently, models used for emergency response at Savannah River Site incorporate the transport and deposition of HTO but do not provide estimates for its potential re-emission from vegetation or soil surface though re-emission could result in prolonged exposure and greater than predicted dose for an individual downwind. A simple model of HTO transport, deposition and re-emission has been developed to examine the potential increase in exposure and dose. The model simulates an initial release of HTO that moves with a mean wind and expands through diffusion as a Gaussian puff. Deposition is modeled using previous estimates of deposition velocity for HTO and re-emission is modeled using a time constant that describes how quickly HTO is transferred between the surface and atmosphere. Additional puffs are created to simulate re-emission of HTO as well as horizontal diffusion across model grid cells. An evaluation of field data indicates that the use of a re-emission module tends to improve model predictions through improved prediction of peak concentration magnitude and location. When considering dose, nearly all of the released material is included in the dose calculation when re-emission is included. Although exposure to HTO through re-emission occurs over a few hours, the incremental increase in dose is relatively small because the atmospheric concentration of re-emitted HTO is much lower than the initial release.

  3. Combining the ICM Eutrophication Model with the SEDZLJ Sediment Transport Model

    Science.gov (United States)

    2012-08-01

    ER D C/ EL T R -1 2 -1 7 Dredging Operations and Environmental Research Program Combining the ICM Eutrophication Model with the SEDZLJ...Dredging Operations and Environmental Research Program ERDC/EL TR-12-17 August 2012 Combining the ICM Eutrophication Model with the SEDZLJ...formulation of the SEDZLJ sediment transport model, coupling of the model with the ICM eutrophication model, validation of the combined codes on a

  4. Hydrogeochemical impact of CO{sub 2} leakage from geological sequestration on shallow potable aquifers

    Energy Technology Data Exchange (ETDEWEB)

    Cahill, A.G.

    2013-09-15

    Over the past 10 years scientists have worked in earnest to understand the potential effects of leakage in order that an informed decision on CCGS implementation can be made. This research can be broadly described as aiming to answer two key questions; how deleterious is leakage of CCGS to groundwater resources? and can it be detected geochemically? Some common hydrochemical development is apparent from the literature however many aspects of hydrogeological and hydrogeochemical impact of leakage into shallow aquifers used in water supply remain unclear. In this Ph.D. study an integrated approach was employed in order to answer the two key questions regarding leakage of CO{sub 2} into shallow aquifers. Consequently a combination of laboratory and field investigations were conducted supported by numerical geochemical modeling in order to identify, constrain and quantify processes controlling groundwater chemistry evolution. The output is 4 journal articles and 3 technical reports. In paper I and technical report I simple batch reactors were employed coupled to comprehensive sediment characterization to determine the likely effects of CO{sub 2} on water chemistry in a range of shallow aquifers. Results showed aquifers can be broadly divided into three types; carbonate dominated, silicate dominated and mixed. Each aquifer type showed distinct water chemistry evolution thus inherent risks vary. These studies also highlighted the complexity of risk assessment and detection caused by the range of formation types potentially overlying storage reservoirs. Investigations described in Papers II, III and technical report II increase applicability to real leakage by observing in situ effects including groundwater flow. A silicate dominated shallow aquifer in Vroegum, western Denmark forms the focus of study upon which a series of investigations were conducted. The main field study involved injection of 1600 kg of gas phase CO{sub 2} into the shallow Vroegum aquifer over 72 days

  5. Transportation

    Science.gov (United States)

    2006-01-01

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

  6. Heat transport modelling in EXTRAP T2R

    Science.gov (United States)

    Frassinetti, L.; Brunsell, P. R.; Cecconello, M.; Drake, J. R.

    2009-02-01

    A model to estimate the heat transport in the EXTRAP T2R reversed field pinch (RFP) is described. The model, based on experimental and theoretical results, divides the RFP electron heat diffusivity χe into three regions, one in the plasma core, where χe is assumed to be determined by the tearing modes, one located around the reversal radius, where χe is assumed not dependent on the magnetic fluctuations and one in the extreme edge, where high χe is assumed. The absolute values of the core and of the reversal χe are determined by simulating the electron temperature and the soft x-ray and by comparing the simulated signals with the experimental ones. The model is used to estimate the heat diffusivity and the energy confinement time during the flat top of standard plasmas, of deep F plasmas and of plasmas obtained with the intelligent shell.

  7. Environmental Transport Input Parameters for the Biosphere Model

    Energy Technology Data Exchange (ETDEWEB)

    M. Wasiolek

    2004-09-10

    This analysis report is one of the technical reports documenting the Environmental Radiation Model for Yucca Mountain, Nevada (ERMYN), a biosphere model supporting the total system performance assessment for the license application (TSPA-LA) for the geologic repository at Yucca Mountain. A graphical representation of the documentation hierarchy for the ERMYN is presented in Figure 1-1. This figure shows relationships among the reports developed for biosphere modeling and biosphere abstraction products for the TSPA-LA, as identified in the ''Technical Work Plan for Biosphere Modeling and Expert Support'' (BSC 2004 [DIRS 169573]) (TWP). This figure provides an understanding of how this report contributes to biosphere modeling in support of the license application (LA). This report is one of the five reports that develop input parameter values for the biosphere model. The ''Biosphere Model Report'' (BSC 2004 [DIRS 169460]) describes the conceptual model and the mathematical model. The input parameter reports, shown to the right of the Biosphere Model Report in Figure 1-1, contain detailed description of the model input parameters. The output of this report is used as direct input in the ''Nominal Performance Biosphere Dose Conversion Factor Analysis'' and in the ''Disruptive Event Biosphere Dose Conversion Factor Analysis'' that calculate the values of biosphere dose conversion factors (BDCFs) for the groundwater and volcanic ash exposure scenarios, respectively. The purpose of this analysis was to develop biosphere model parameter values related to radionuclide transport and accumulation in the environment. These parameters support calculations of radionuclide concentrations in the environmental media (e.g., soil, crops, animal products, and air) resulting from a given radionuclide concentration at the source of contamination (i.e., either in groundwater or in volcanic ash). The analysis

  8. MOZART, a global chemical transport model for ozone and related chemical tracers: 1. Model description

    Science.gov (United States)

    Brasseur, G. P.; Hauglustaine, D. A.; Walters, S.; Rasch, P. J.; Müller, J.-F.; Granier, C.; Tie, X. X.

    1998-11-01

    We present a new global three-dimensional chemical-transport model (called MOZART) developed in the framework of the NCAR Community Climate Model (CCM) and aimed at studying the distribution and budget of tropospheric ozone and its precursors. The model, developed with a horizontal resolution of 2.8° in longitude and latitude, includes 25 levels in the vertical between the Earth's surface and an upper boundary located at approximately 35 km altitude. In its present configuration the model calculates the global distribution of 56 chemical constituents with a timestep of 20 min, and accounts for surface emission and deposition, large-scale advective transport, subscale convective and boundary layer exchanges, chemical and photochemical transformations, as well as wet scavenging. Transport is simulated "off line" from CCM with dynamical variables provided every 3 hours from preestablished history tapes. Advection is calculated using the semi-Lagrangian transport scheme [Rasch and Williamson, 1990] developed for the MATCH model of Rasch et al. [1997]. Convective and boundary layer transports are expressed according to Hack [1994] and Holtslag and Boville [1993], respectively. A detailed evaluation of the model results is provided in a companion paper [Hauglustaine et al., this issue]. An analysis of the spatial and temporal variability in the chemical fields predicted by the model suggests that regional events such as summertime ozone episodes in polluted areas can be simulated by MOZART.

  9. Multispecies reactive transport modelling of electrokinetic remediation of harbour sediments.

    Science.gov (United States)

    Masi, Matteo; Ceccarini, Alessio; Iannelli, Renato

    2017-03-15

    We implemented a numerical model to simulate transport of multiple species and geochemical reactions occurring during electrokinetic remediation of metal-contaminated porous media. The main phenomena described by the model were: (1) species transport by diffusion, electromigration and electroosmosis, (2) pH-dependent buffering of H + , (3) adsorption of metals onto particle surfaces, (4) aqueous speciation, (5) formation and dissolution of solid precipitates. The model was applied to simulate the electrokinetic extraction of heavy metals (Pb, Zn and Ni) from marine harbour sediments, characterized by a heterogeneous solid matrix, high buffering capacity and aged pollution. A good agreement was found between simulations of pH, electroosmotic flow and experimental results. The predicted residual metal concentrations in the sediment were also close to experimental profiles for all of the investigated metals. Some removal overestimation was observed in the regions close to the anode, possibly due to the significant metal content bound to residual fraction. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. 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.

  11. Impact of transport model errors on the global and regional methane emissions estimated by inverse modelling

    Directory of Open Access Journals (Sweden)

    R. Locatelli

    2013-10-01

    Full Text Available A modelling experiment has been conceived to assess the impact of transport model errors on methane emissions estimated in an atmospheric inversion system. Synthetic methane observations, obtained from 10 different model outputs from the international TransCom-CH4 model inter-comparison exercise, are combined with a prior scenario of methane emissions and sinks, and integrated into the three-component PYVAR-LMDZ-SACS (PYthon VARiational-Laboratoire de Météorologie Dynamique model with Zooming capability-Simplified Atmospheric Chemistry System inversion system to produce 10 different methane emission estimates at the global scale for the year 2005. The same methane sinks, emissions and initial conditions have been applied to produce the 10 synthetic observation datasets. The same inversion set-up (statistical errors, prior emissions, inverse procedure is then applied to derive flux estimates by inverse modelling. Consequently, only differences in the modelling of atmospheric transport may cause differences in the estimated fluxes. In our framework, we show that transport model errors lead to a discrepancy of 27 Tg yr−1 at the global scale, representing 5% of total methane emissions. At continental and annual scales, transport model errors are proportionally larger than at the global scale, with errors ranging from 36 Tg yr−1 in North America to 7 Tg yr−1 in Boreal Eurasia (from 23 to 48%, respectively. At the model grid-scale, the spread of inverse estimates can reach 150% of the prior flux. Therefore, transport model errors contribute significantly to overall uncertainties in emission estimates by inverse modelling, especially when small spatial scales are examined. Sensitivity tests have been carried out to estimate the impact of the measurement network and the advantage of higher horizontal resolution in transport models. The large differences found between methane flux estimates inferred in these different configurations highly

  12. Reactive transport modeling of nitrogen in Seine River sediments

    Science.gov (United States)

    Akbarzadeh, Z.; Laverman, A.; Raimonet, M.; Rezanezhad, F.; Van Cappellen, P.

    2016-02-01

    Biogeochemical processes in sediments have a major impact on the fate and transport of nitrogen (N) in river systems. Organic matter decomposition in bottom sediments releases inorganic N species back to the stream water, while denitrification, anammox and burial of organic matter remove bioavailable N from the aquatic environment. To simulate N cycling in river sediments, a multi-component reactive transport model has been developed in MATLAB®. The model includes 3 pools of particulate organic N, plus pore water nitrate, nitrite, nitrous oxide and ammonium. Special attention is given to the production and consumption of nitrite, a N species often neglected in early diagenetic models. Although nitrite is usually considered to be short-lived, elevated nitrite concentrations have been observed in freshwater streams, raising concerns about possible toxic effects. We applied the model to sediment data sets collected at two locations in the Seine River, one upstream, the other downstream, of the largest wastewater treatment plant (WWTP) of the Paris conurbation. The model is able to reproduce the key features of the observed pore water depth profiles of the different nitrogen species. The modeling results show that the presence of oxygen in the overlying water plays a major role in controlling the exchanges of nitrite between the sediments and the stream water. In August 2012, sediments upstream of the WWTP switch from being a sink to a source of nitrite as the overlying water becomes anoxic. Downstream sediments remain a nitrite sink in oxic and anoxic conditions. Anoxic bottom waters at the upstream location promote denitrification, which produces nitrite, while at the downstream site, anammox and DNRA are important removal processes of nitrite.

  13. The balance model for heat transport from hydrolytic reaction mixture

    Directory of Open Access Journals (Sweden)

    Janacova Dagmar

    2017-01-01

    Full Text Available The content of the paper is the industrial application of enzyme hydrolysis of tanning solids waste with a view to minimizing the price of enzyme hydrolysate product, which has widely used. On the base of the energy balance of the enzymatic hydrolysis we estimated the critical minimal charge of a tanning drum. We performed of the critical minimal on the basis of a balance model for heat transport from reaction mixture into the environment through reactor wall. Employing a tanning drum for hydrolytic reaction allows to process tanning wastes in the place of their origin. It means thus considerably to enhancing economics of the whole process.

  14. A Model of Dispersion in Pollutant Transport; Un modelo de dispersion en el transporte de contaminantes

    Energy Technology Data Exchange (ETDEWEB)

    Maron Dominguez, David Ernesto [Instituto Superior Politecnico Jose A. Echeverrria (Cuba)

    2002-09-01

    A numeric model is show for the solution of the inverse problem in pollutant transport. Quadratic and cubic elements were used in the discretization by the MEF of the equation of the dispersion. The algorithms of the inverse model are verified and compared with analytic solutions reported in the literature. The application of the model to the calibration of the parameters of a wetland used a s a filter in the treatment of wastewater is shown. The wetland was created in the laboratory and measurements of sodium fluorescein concentrations of a test were used as tracer. The dispersion coefficient, the retardation coefficient, the degradation coefficient, and the parameter of weight of the discretization in time were gauged. The results shown prove the good approximation of the dispersion coefficient obtained with a value estimated by another method. The graphs of the adjustments obtained are also shown. [Spanish] Se muestra un modelo numerico para la resolucion del problema inverso en el transporte de contaminantes. Se emplearon elementos cuadraticos y cubicos en la discretizacion por el metodo de los elementos finitos de la ecuacion de la ecuacion de la dispersion. Se verifican y se comparan los algoritmos del modelo inverso con una solucion analitica reportada en la literatura. Se muestra la aplicacion del modelo a la calibracion de los parametros de un humedal utilizado como filtro en el tratamiento de agua residuales. El humedal se construyo en el laboratorio y se utilizaron mediciones de concentraciones de fluoresceina sodica de una prueba de trazado. Se calibraron el coeficiente de dispersion, el coeficiente de retardo, el coeficiente de degradacion y el parametro de peso de la discretizacion en el tiempo. Se muestran los resultados obtenidos, comprobandose la buena aproximacion del coeficiente de dispersion con un valor estimado por otro metodo. Se muestran las graficas de los ajustes que se lograron.

  15. Three dimensional heat transport modeling in Vossoroca reservoir

    Science.gov (United States)

    Arcie Polli, Bruna; Yoshioka Bernardo, Julio Werner; Hilgert, Stephan; Bleninger, Tobias

    2017-04-01

    Freshwater reservoirs are used for many purposes as hydropower generation, water supply and irrigation. In Brazil, according to the National Energy Balance of 2013, hydropower energy corresponds to 70.1% of the Brazilian demand. Superficial waters (which include rivers, lakes and reservoirs) are the most used source for drinking water supply - 56% of the municipalities use superficial waters as a source of water. The last two years have shown that the Brazilian water and electricity supply is highly vulnerable and that improved management is urgently needed. The construction of reservoirs affects physical, chemical and biological characteristics of the water body, e.g. stratification, temperature, residence time and turbulence reduction. Some water quality issues related to reservoirs are eutrophication, greenhouse gas emission to the atmosphere and dissolved oxygen depletion in the hypolimnion. The understanding of the physical processes in the water body is fundamental to reservoir management. Lakes and reservoirs may present a seasonal behavior and stratify due to hydrological and meteorological conditions, and especially its vertical distribution may be related to water quality. Stratification can control heat and dissolved substances transport. It has been also reported the importance of horizontal temperature gradients, e.g. inflows and its density and processes of mass transfer from shallow to deeper regions of the reservoir, that also may impact water quality. Three dimensional modeling of the heat transport in lakes and reservoirs is an important tool to the understanding and management of these systems. It is possible to estimate periods of large vertical temperature gradients, inhibiting vertical transport and horizontal gradients, which could be responsible for horizontal transport of heat and substances (e.g. differential cooling or inflows). Vossoroca reservoir was constructed in 1949 by the impoundment of São João River and is located near to

  16. Environmental Transport Input Parameters for the Biosphere Model

    Energy Technology Data Exchange (ETDEWEB)

    M. A. Wasiolek

    2003-06-27

    This analysis report is one of the technical reports documenting the Environmental Radiation Model for Yucca Mountain Nevada (ERMYN), a biosphere model supporting the total system performance assessment (TSPA) for the geologic repository at Yucca Mountain. A graphical representation of the documentation hierarchy for the ERMYN is presented in Figure 1-1. This figure shows relationships among the reports developed for biosphere modeling and biosphere abstraction products for the TSPA, as identified in the ''Technical Work Plan: for Biosphere Modeling and Expert Support'' (TWP) (BSC 2003 [163602]). Some documents in Figure 1-1 may be under development and not available when this report is issued. This figure provides an understanding of how this report contributes to biosphere modeling in support of the license application (LA), but access to the listed documents is not required to understand the contents of this report. This report is one of the reports that develops input parameter values for the biosphere model. The ''Biosphere Model Report'' (BSC 2003 [160699]) describes the conceptual model, the mathematical model, and the input parameters. The purpose of this analysis is to develop biosphere model parameter values related to radionuclide transport and accumulation in the environment. These parameters support calculations of radionuclide concentrations in the environmental media (e.g., soil, crops, animal products, and air) resulting from a given radionuclide concentration at the source of contamination (i.e., either in groundwater or volcanic ash). The analysis was performed in accordance with the TWP (BSC 2003 [163602]). This analysis develops values of parameters associated with many features, events, and processes (FEPs) applicable to the reference biosphere (DTN: M00303SEPFEPS2.000 [162452]), which are addressed in the biosphere model (BSC 2003 [160699]). The treatment of these FEPs is described in BSC (2003 [160699

  17. The energy logistic model for analyses of transportation- and energy systems; Energilogistikmodell foer systemberaekningar av transport- och energifoersoerjningssystem

    Energy Technology Data Exchange (ETDEWEB)

    Blinge, M.

    1995-05-01

    The Energy Logistic Model has been improved to become a tool for analysis of all production processes, transportation systems and systems including several energy users and several fuels. Two cases were studied. The first case deals with terminal equipment for inter modal transport systems and the second case deals with diesel fuelled trucks, cranes and machines in the Goeteborg area. In both cases, the environmental improvements of the city air quality are analyzed when natural gas is substituted for diesel oil. The comparison between inter modal transport and road haulage shows that the environmental impacts from the operations at the terminal are limited, and that the potential for environmental benefits when using inter modal transport is improving with the transportation distance. The choice of electricity production system is of great importance when calculating the environmental impact from railway traffic in the total analysis of the transportation system. 13 refs, 27 tabs

  18. A computerized coal-water slurry transportation model

    Energy Technology Data Exchange (ETDEWEB)

    Ljubicic, B.R.; Trostad, B. [Univ. of North Dakota, Grand Forks, ND (United States); Bukurov, Z.; Cvijanovic, P. [Univ. of Novi Sad (Yugoslavia)

    1995-12-01

    Coal-water fuel (CWF) technology has been developed to the point where full-scale commercialization is just a matter of gaining sufficient market confidence in the price stability of alternate fossil fuels. In order to generalize alternative fuel cost estimates for the desired combinations of processing and/or transportation, a great deal of flexibility is required owing to the understood lack of precision in many of the newly emerging coal technologies. Previously, decisions regarding the sequential and spatial arrangement of the various process steps were made strictly on the basis of experience, simplified analysis, and intuition. Over the last decade, computer modeling has progressed from empirically based correlation to that of intricate mechanistic analysis. Nomograms, charts, tables, and many simple rules of thumb have been made obsolete by the availability of complex computer models. Given the ability to view results graphically in real or near real time, the engineer can immediately verify, from a practical standpoint, whether the initial assumptions and inputs were indeed valid. If the feasibility of a project is being determined in the context of a lack of specific data, the ability to provide a dynamic software-based solution is crucial. Furthermore, the resulting model can be used to establish preliminary operating procedures, test control logic, and train plant/process operators. Presented in this paper is a computerized model capable of estimating the delivered cost of CWF. The model uses coal-specific values, process and transport requirements, terrain factors, and input costs to determine the final operating configuration, bill of materials, and, ultimately, the capital, operating, and unit costs.

  19. Co-evolution of transportation and land use : modeling historical dependencies in land use and transportation decision making.

    Science.gov (United States)

    2009-11-01

    The interaction between land use and transportation has long been the central issue in urban and regional planning. Models of such : interactions provide vital information to support many public policy decisions, such as land supply, infrastructure p...

  20. A mechanistic physicochemical model of carbon dioxide transport in blood.

    Science.gov (United States)

    O'Neill, David P; Robbins, Peter A

    2017-02-01

    A number of mathematical models have been produced that, given the Pco2 and Po2 of blood, will calculate the total concentrations for CO2 and O2 in blood. However, all these models contain at least some empirical features, and thus do not represent all of the underlying physicochemical processes in an entirely mechanistic manner. The aim of this study was to develop a physicochemical model of CO2 carriage by the blood to determine whether our understanding of the physical chemistry of the major chemical components of blood together with their interactions is sufficiently strong to predict the physiological properties of CO2 carriage by whole blood. Standard values are used for the ionic composition of the blood, the plasma albumin concentration, and the hemoglobin concentration. All Km values required for the model are taken from the literature. The distribution of bicarbonate, chloride, and H+ ions across the red blood cell membrane follows that of a Gibbs-Donnan equilibrium. The system of equations that results is solved numerically using constraints for mass balance and electroneutrality. The model reproduces the phenomena associated with CO2 carriage, including the magnitude of the Haldane effect, very well. The structural nature of the model allows various hypothetical scenarios to be explored. Here we examine the effects of 1) removing the ability of hemoglobin to form carbamino compounds; 2) allowing a degree of Cl- binding to deoxygenated hemoglobin; and 3) removing the chloride (Hamburger) shift. The insights gained could not have been obtained from empirical models. This study is the first to incorporate a mechanistic model of chloride-bicarbonate exchange between the erythrocyte and plasma into a full physicochemical model of the carriage of carbon dioxide in blood. The mechanistic nature of the model allowed a theoretical study of the quantitative significance for carbon dioxide transport of carbamino compound formation; the putative binding of chloride

  1. Modeling sediment transport in Qatar: Application for coastal development planning.

    Science.gov (United States)

    Yousif, Ruqaiya; Warren, Christopher; Ben-Hamadou, Radhouan; Husrevoglu, Sinan

    2017-10-06

    Hydrodynamics and sediment transport are key physical processes contributing to habitat structure within the marine environment. Coastal development that results in the alteration of these processes (e.g., changing water flushing and/or sedimentation rates) can have detrimental impacts on sensitive systems. This is a current, relevant issue in Qatar as its coastal regions continue to be developed, not only around the capital of Doha, but in many areas around this Arabian Gulf peninsula. The northeastern Qatari coast is comprised of diverse and sensitive flora and fauna such as seagrass and macroalgae meadows, coral reefs and patches, turtles, and dugongs that tolerate harsh environmental conditions. In the near future, this area may see a rise in anthropogenic activity in the form of coastal development projects. These projects will add to existing natural stresses, such as high temperature, high salinity, and low rates of precipitation. Consequently, there is a need to characterize this area and assess the potential impacts that these anthropogenic activities may have on the region. In the present study, a novel sediment transport model is described and used to demonstrate the potential impact of altering hydrodynamics and subsequent sediment transport along the northeastern Qatar nearshore marine environment. The developed models will be tested using potential scenarios of future anthropogenic activities forecasted to take place in the area. The results will show the effects on water and sediment behavior and provide a scientific approach for key stakeholders to make decisions with respect to the management of the considered coastal zone. Furthermore, it provides a tool and framework that can be utilized in environmental impact assessment and associated hydrodynamic studies along other areas of the Qatari coastal zone. Integr Environ Assess Manag 2017;00:000-000. ©2017 SETAC. © 2017 SETAC.

  2. Low-Rank Kalman Filtering in Subsurface Contaminant Transport Models

    KAUST Repository

    El Gharamti, Mohamad

    2010-12-01

    Understanding the geology and the hydrology of the subsurface is important to model the fluid flow and the behavior of the contaminant. It is essential to have an accurate knowledge of the movement of the contaminants in the porous media in order to track them and later extract them from the aquifer. A two-dimensional flow model is studied and then applied on a linear contaminant transport model in the same porous medium. Because of possible different sources of uncertainties, the deterministic model by itself cannot give exact estimations for the future contaminant state. Incorporating observations in the model can guide it to the true state. This is usually done using the Kalman filter (KF) when the system is linear and the extended Kalman filter (EKF) when the system is nonlinear. To overcome the high computational cost required by the KF, we use the singular evolutive Kalman filter (SEKF) and the singular evolutive extended Kalman filter (SEEKF) approximations of the KF operating with low-rank covariance matrices. The SEKF can be implemented on large dimensional contaminant problems while the usage of the KF is not possible. Experimental results show that with perfect and imperfect models, the low rank filters can provide as much accurate estimates as the full KF but at much less computational cost. Localization can help the filter analysis as long as there are enough neighborhood data to the point being analyzed. Estimating the permeabilities of the aquifer is successfully tackled using both the EKF and the SEEKF.

  3. Monte Carlo path sampling approach to modeling aeolian sediment transport

    Science.gov (United States)

    Hardin, E. J.; Mitasova, H.; Mitas, L.

    2011-12-01

    Coastal communities and vital infrastructure are subject to coastal hazards including storm surge and hurricanes. Coastal dunes offer protection by acting as natural barriers from waves and storm surge. During storms, these landforms and their protective function can erode; however, they can also erode even in the absence of storms due to daily wind and waves. Costly and often controversial beach nourishment and coastal construction projects are common erosion mitigation practices. With a more complete understanding of coastal morphology, the efficacy and consequences of anthropogenic activities could be better predicted. Currently, the research on coastal landscape evolution is focused on waves and storm surge, while only limited effort is devoted to understanding aeolian forces. Aeolian transport occurs when the wind supplies a shear stress that exceeds a critical value, consequently ejecting sand grains into the air. If the grains are too heavy to be suspended, they fall back to the grain bed where the collision ejects more grains. This is called saltation and is the salient process by which sand mass is transported. The shear stress required to dislodge grains is related to turbulent air speed. Subsequently, as sand mass is injected into the air, the wind loses speed along with its ability to eject more grains. In this way, the flux of saltating grains is itself influenced by the flux of saltating grains and aeolian transport becomes nonlinear. Aeolian sediment transport is difficult to study experimentally for reasons arising from the orders of magnitude difference between grain size and dune size. It is difficult to study theoretically because aeolian transport is highly nonlinear especially over complex landscapes. Current computational approaches have limitations as well; single grain models are mathematically simple but are computationally intractable even with modern computing power whereas cellular automota-based approaches are computationally efficient

  4. The Extended Generalized Cost Concept and its Application in Freight Transport and General Equilibrium Modeling

    OpenAIRE

    Tavasszy, L; Davydenko, I.; Ruijgrok, K.

    2009-01-01

    The integration of Spatial Equilibrium models and Freight transport network models is important to produce consistent scenarios for future freight transport demand. At various spatial scales, we see the changes in production, trade, logistics networking and transportation, being driven by mass-individualization and changes in factor costs. In this paper we focus on the latter driver for changes in freight transport. The cost of interaction plays an important role in many modeling frameworks t...

  5. Modelling of transport and biogeochemical processes in pollution plumes: Literature review of model development

    DEFF Research Database (Denmark)

    Brun, A.; Engesgaard, Peter Knudegaard

    2002-01-01

    A literature survey shows how biogeochemical (coupled organic and inorganic reaction processes) transport models are based on considering the complete biodegradation process as either a single- or as a two-step process. It is demonstrated that some two-step process models rely on the Partial Equi....... A second paper [J. Hydrol. 256 (2002) 230-249], reports the application of the model to a field study of biogeochemical transport processes in a landfill plume in Denmark (Vejen). (C) 2002 Elsevier Science B.V. All rights reserved....

  6. Multiscale modeling of spin transport across a diffuse interface

    Science.gov (United States)

    Chureemart, J.; Cuadrado, R.; Chureemart, P.; Chantrell, R. W.

    2017-12-01

    We present multiscale calculations to describe the spin transport behavior of the Co/Cu bilayer structure including the effect of the interface. The multiscale approach introduces the connection between the ab initio calculation used to describe the electronic structure of the system and the generalized spin accumulation model employed to describe the spin transport behavior. We have applied our model to atomically smooth and diffuse interfaces. The results demonstrate the huge importance of the use of first principle calculations, not only due to the interfacial coordinates optimization but also the magnetic and electronic properties obtained through the electronic structure. The system including the effect of interface with and without the charge fluctuation are studied. The results indicate that changes of electronic structure at the Co/Cu interface give rise to an interfacial resistance distributed over several atomic planes, similar to the effect of interface diffusion. We argue that even atomically smooth Co/Cu interfaces have properties analogous to a diffuse interface due to the variation of electronic structure at the interface.

  7. Model Transport: Towards Scalable Transfer Learning on Manifolds

    DEFF Research Database (Denmark)

    Freifeld, Oren; Hauberg, Søren; Black, Michael J.

    2014-01-01

    ordinary Rn-transfer learning ideas, the manifold structure prevents it. We overcome this by basing our method on inner-product-preserving parallel transport, a well-known tool widely used in other problems of statistics on manifolds in computer vision. At first, this straightforward idea seems to suffer......We consider the intersection of two research fields: transfer learning and statistics on manifolds. In particular, we consider, for manifold-valued data, transfer learning of tangent-space models such as Gaussians distributions, PCA, regression, or classifiers. Though one would hope to simply use...... “commutes” with learning. Consequently, our compact framework, applicable to a large class of manifolds, is not restricted by the size of either the training or test sets. We demonstrate the approach by transferring PCA and logistic-regression models of real-world data involving 3D shapes and image...

  8. 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.

  9. Modelling of sand transport under wave-generated sheet flows with a RANS diffusion model

    NARCIS (Netherlands)

    Hassan, Wael; Ribberink, Jan S.

    2010-01-01

    A 1DV-RANS diffusion model is used to study sand transport processes in oscillatory flat-bed/sheet flow conditions. The central aim is the verification of the model with laboratory data and to identify processes controlling the magnitude and direction (‘onshore’/‘offshore’) of the net time-averaged

  10. Inverse modeling of methane sources and sinks using the adjoint of a global transport model

    NARCIS (Netherlands)

    Houweling, S; Kaminski, T; Dentener, F; Lelieveld, J; Heimann, M

    1999-01-01

    An inverse modeling method is presented to evaluate the sources and sinks of atmospheric methane. An adjoint version of a global transport model has been used to estimate these fluxes at a relatively high spatial and temporal resolution. Measurements from 34 monitoring stations and 11 locations

  11. Process Modeling of Flow, Transport, and Biodegradation in Landfill Bioreactors

    Science.gov (United States)

    Oldenburg, C. M.; Borglin, S. E.; Hazen, T. C.

    2001-12-01

    The need to control gas and leachate production and minimize refuse volume has motivated laboratory experiments and model development for design and assessment of bioremediation treatment processes. In parallel with landfill bioreactor laboratory experiments, we have developed T2LBM, a module for the TOUGH2 multiphase flow and transport simulator that implements a Landfill Bioreactor Model. T2LBM provides simulation capability for the processes of aerobic or anaerobic biodegradation of municipal solid waste and the associated three-dimensional flow and transport of gas, liquid, and heat through the refuse mass. T2LBM considers the components water, acetic acid, carbon dioxide, methane, oxygen, and nitrogen in aqueous and gas phases, with partitioning specified by temperature-dependent Henry's coefficients. T2LBM incorporates a Monod kinetic rate law for the exothermic biodegradation of acetic acid in the aqueous phase by either aerobic or anaerobic microbes as controlled by the local oxygen concentration. Methane and carbon dioxide generation due to biodegradation with corresponding thermal effects are modeled. Acetic acid is considered a proxy for all biodegradable substrates in the refuse. Aerobic and anaerobic microbes are assumed to be immobile and not limited by nutrients in their growth. Although a simplification of complex landfill processes, T2LBM shows reasonable agreement to published laboratory experiments of biodegradation and gas production depending on the choice of numerous input parameters. Simulations of the landfill bioreactor laboratory experiments show that the mechanistic approach of T2LBM can be used to model bioremediation assessment indicators such as oxygen consumption associated with respiration tests. This work was supported by Laboratory Directed Research and Development Funds at Lawrence Berkeley National Laboratory under Department of Energy Contract No. DE-AC03-76SF00098.

  12. Modeling Blazar Spectra by Solving an Electron Transport Equation

    Science.gov (United States)

    Lewis, Tiffany; Finke, Justin; Becker, Peter A.

    2018-01-01

    Blazars are luminous active galaxies across the entire electromagnetic spectrum, but the spectral formation mechanisms, especially the particle acceleration, in these sources are not well understood. We develop a new theoretical model for simulating blazar spectra using a self-consistent electron number distribution. Specifically, we solve the particle transport equation considering shock acceleration, adiabatic expansion, stochastic acceleration due to MHD waves, Bohm diffusive particle escape, synchrotron radiation, and Compton radiation, where we implement the full Compton cross-section for seed photons from the accretion disk, the dust torus, and 26 individual broad lines. We used a modified Runge-Kutta method to solve the 2nd order equation, including development of a new mathematical method for normalizing stiff steady-state ordinary differential equations. We show that our self-consistent, transport-based blazar model can qualitatively fit the IR through Fermi g-ray data for 3C 279, with a single-zone, leptonic configuration. We use the solution for the electron distribution to calculate multi-wavelength SED spectra for 3C 279. We calculate the particle and magnetic field energy densities, which suggest that the emitting region is not always in equipartition (a common assumption), but sometimes matter dominated. The stratified broad line region (based on ratios in quasar reverberation mapping, and thus adding no free parameters) improves our estimate of the location of the emitting region, increasing it by ~5x. Our model provides a novel view into the physics at play in blazar jets, especially the relative strength of the shock and stochastic acceleration, where our model is well suited to distinguish between these processes, and we find that the latter tends to dominate.

  13. Impact of Transport Zone Number in Simulation Models on Cost-Benefit Analysis Results in Transport Investments

    Science.gov (United States)

    Chmielewski, Jacek

    2017-10-01

    Nowadays, feasibility studies need to be prepared for all planned transport investments, mainly those co-financed with UE grants. One of the fundamental aspect of feasibility study is the economic justification of an investment, evaluated in an area of so called cost-benefit analysis (CBA). The main goal of CBA calculation is to prove that a transport investment is really important for the society and should be implemented as economically efficient one. It can be said that the number of hours (PH – passengers hours) in trips and travelled kilometres (PK – passengers kilometres) are the most important for CBA results. The differences between PH and PK calculated for particular investment scenarios are the base for benefits calculation. Typically, transport simulation models are the best source for such data. Transport simulation models are one of the most powerful tools for transport network planning. They make it possible to evaluate forecast traffic volume and passenger flows in a public transport system for defined scenarios of transport and area development. There are many different transport models. Their construction is often similar, and they mainly differ in the level of their accuracy. Even models for the same area may differ in this matter. Typically, such differences come from the accuracy of supply side representation: road and public transport network representation. In many cases only main roads and a public transport network are represented, while local and service roads are eliminated as a way of reality simplification. This also enables a faster and more effective calculation process. On the other hand, the description of demand part of these models based on transport zones is often stable. Difficulties with data collection, mainly data on land use, resulted in the lack of changes in the analysed land division into so called transport zones. In this paper the author presents an influence of land division on the results of traffic analyses, and

  14. P-adic model of transport in porous disordered media

    Science.gov (United States)

    Khrennikov, Adrei Yu.; Oleschko, Klaudia

    2014-05-01

    The soil porosity and permeability are the most important quantitative indicators of soil dynamics under the land-use change. The main problema in the modeling of this dynamic is still poor correlation between the real measuring data and the mathematical and computer simulation models. In order to overpassed this deep divorce we have designed a new technique, able to compare the data arised from the multiscale image analices and time series of the basic physical properties dynamics in porous media studied in time and space. We present a model of the diffusion reaction type describing transport in disordered porous media, e.g., water or oil flow in a complex network of pores. Our model is based on p-adic representation of such networks. This is a kind of fractal representation. We explore advantages of p- adic representation, namely, the possibility to endow p-adic trees with an algebraic structure and ultrametric topology and, hence, to apply analysis which have (at least some) similarities with ordinary real analysis on the straight line. We present the system of two diffusion reaction equations describing propagation of particles in networks of pores in disordered media. As an application, one can consider water transport through the soil pore Networks, or oil flow through capillaries nets. Under some restrictions on potentials and rate coefficients we found the stationary regime corresponding to water content or concentration of oil in a cluster of capillaries. Usage of p-adic analysis (in particular, p-adic wavelets) gives a possibility to find the stationary solution in the analytic form which makes possible to present a clear pedological or geological picture of the process. The mathematical model elaborated in this paper (Khrennikov, 2013) can be applied to variety of problems from water concentration in aquifers to the problem of formation of oil reservoirs in disordered media with porous structures. Another possible application may have real practical

  15. Hydrogeochemical Analysis of an Overexploited Aquifer In Bangladesh Toward Managed Aquifer Recharge Project Implementation

    Science.gov (United States)

    Rahman, M. A.; Wiegand, B. A.; Pervin, M.; Sauter, M.

    2012-12-01

    In most parts of the upper Dupitila aquifer (Dhaka City, Bangladesh) the average groundwater depletion reaches 2-3 m/year due to increasing water demands of the growing population. To counteract overexploitation of the aquifer, a more sustainable water management is required. The analysis of the local water resources system suggests that Managed Aquifer Recharge (MAR) would help to restore groundwater resources to strengthen water supply of Dhaka City, e.g., by using collected urban monsoon runoff and excess surface water from rivers. To assess possible effects of surface water or rainwater injection on groundwater quality, a comprehensive hydrogeochemical survey of the Dupitila aquifer is required. This paper presents hydrogeochemical data to document the current status of groundwater quality and to evaluate potential groundwater pollution by mobilization of hazardous chemicals as a result of changes in the hydrochemical equilibria. We performed a comprehensive review of available secondary data sources and will present new results from hydrochemical and Sr isotope investigations of water samples that were conducted within this study. Currently, groundwater quality in the upper Dupitila aquifer is characterized by variations in the electrical conductivity in the range of 200 to 1100 μS/cm, which may indicate some anthropogenic contamination by leakage from waste disposal including the sewage network and from surface water infiltration into the groundwater aquifer. Dissolved oxygen concentrations range from 1.0 to 4.9 mg/L (average 2.5 mg/L) in the upper Dupitila aquifer, while the lower Dupilita aquifer shows dissolved oxygen concentrations in the range 0 to 0.7 mg/L. Concentrations of major ions show some variation primarily due to a sedimentologically/mineralogically heterogeneous aquifer composition (sand, gravel, clay horizons), but may also be affected by anthropogenic processes. The groundwater composition is predominated by Ca-Mg-HCO3 and saturation values

  16. A reactive transport model for Marcellus shale weathering

    Science.gov (United States)

    Heidari, Peyman; Li, Li; Jin, Lixin; Williams, Jennifer Z.; Brantley, Susan L.

    2017-11-01

    Shale formations account for 25% of the land surface globally and contribute a large proportion of the natural gas used in the United States. One of the most productive shale-gas formations is the Marcellus, a black shale that is rich in organic matter and pyrite. As a first step toward understanding how Marcellus shale interacts with water in the surface or deep subsurface, we developed a reactive transport model to simulate shale weathering under ambient temperature and pressure conditions, constrained by soil and water chemistry data. The simulation was carried out for 10,000 years since deglaciation, assuming bedrock weathering and soil genesis began after the last glacial maximum. Results indicate weathering was initiated by pyrite dissolution for the first 1000 years, leading to low pH and enhanced dissolution of chlorite and precipitation of iron hydroxides. After pyrite depletion, chlorite dissolved slowly, primarily facilitated by the presence of CO2 and organic acids, forming vermiculite as a secondary mineral. A sensitivity analysis indicated that the most important controls on weathering include the presence of reactive gases (CO2 and O2), specific surface area, and flow velocity of infiltrating meteoric water. The soil chemistry and mineralogy data could not be reproduced without including the reactive gases. For example, pyrite remained in the soil even after 10,000 years if O2 was not continuously present in the soil column; likewise, chlorite remained abundant and porosity remained small if CO2 was not present in the soil gas. The field observations were only simulated successfully when the modeled specific surface areas of the reactive minerals were 1-3 orders of magnitude smaller than surface area values measured for powdered minerals. Small surface areas could be consistent with the lack of accessibility of some fluids to mineral surfaces due to surface coatings. In addition, some mineral surface is likely interacting only with equilibrated pore

  17. Modeling watershed-scale solute transport using an integrated, process-based hydrologic model with applications to bacterial fate and transport

    Science.gov (United States)

    Niu, Jie; Phanikumar, Mantha S.

    2015-10-01

    Distributed hydrologic models that simulate fate and transport processes at sub-daily timescales are useful tools for estimating pollutant loads exported from watersheds to lakes and oceans downstream. There has been considerable interest in the application of integrated process-based hydrologic models in recent years. While the models have been applied to address questions of water quantity and to better understand linkages between hydrology and land surface processes, routine applications of these models to address water quality issues are currently limited. In this paper, we first describe a general process-based watershed-scale solute transport modeling framework, based on an operator splitting strategy and a Lagrangian particle transport method combined with dispersion and reactions. The transport and the hydrologic modules are tightly coupled and the interactions among different hydrologic components are explicitly modeled. We test transport modules using data from plot-scale experiments and available analytical solutions for different hydrologic domains. The numerical solutions are also compared with an analytical solution for groundwater transit times with interactions between surface and subsurface flows. Finally, we demonstrate the application of the model to simulate bacterial fate and transport in the Red Cedar River watershed in Michigan and test hypotheses about sources and transport pathways. The watershed bacterial fate and transport model is expected to be useful for making near real-time predictions at marine and freshwater beaches.

  18. How uncertainty in socio-economic variables affects large-scale transport model forecasts

    DEFF Research Database (Denmark)

    Manzo, Stefano; Nielsen, Otto Anker; Prato, Carlo Giacomo

    2015-01-01

    time, especially with respect to large-scale transport models. The study described in this paper contributes to fill the gap by investigating the effects of uncertainty in socio-economic variables growth rate projections on large-scale transport model forecasts, using the Danish National Transport...

  19. Modelling transport phenomena in a multi-physics context

    Energy Technology Data Exchange (ETDEWEB)

    Marra, Francesco [Dipartimento di Ingegneria Chimica e Alimentare - Università degli studi di Salerno Via Ponte Don Melillo - 84084 Fisciano SA (Italy)

    2015-01-22

    Innovative heating research on cooking, pasteurization/sterilization, defrosting, thawing and drying, often focuses on areas which include the assessment of processing time, evaluation of heating uniformity, studying the impact on quality attributes of the final product as well as considering the energy efficiency of these heating processes. During the last twenty years, so-called electro-heating-processes (radio-frequency - RF, microwaves - MW and ohmic - OH) gained a wide interest in industrial food processing and many applications using the above mentioned technologies have been developed with the aim of reducing processing time, improving process efficiency and, in many cases, the heating uniformity. In the area of innovative heating, electro-heating accounts for a considerable portion of both the scientific literature and commercial applications, which can be subdivided into either direct electro-heating (as in the case of OH heating) where electrical current is applied directly to the food or indirect electro-heating (e.g. MW and RF heating) where the electrical energy is firstly converted to electromagnetic radiation which subsequently generates heat within a product. New software packages, which make easier solution of PDEs based mathematical models, and new computers, capable of larger RAM and more efficient CPU performances, allowed an increasing interest about modelling transport phenomena in systems and processes - as the ones encountered in food processing - that can be complex in terms of geometry, composition, boundary conditions but also - as in the case of electro-heating assisted applications - in terms of interaction with other physical phenomena such as displacement of electric or magnetic field. This paper deals with the description of approaches used in modelling transport phenomena in a multi-physics context such as RF, MW and OH assisted heating.

  20. A Model of Cadmium Uptake and Transport in Caco-2 Cells.

    Science.gov (United States)

    Gerasimenko, T N; Senyavina, N V; Anisimov, N U; Tonevitskaya, S A

    2016-05-01

    We created a physiologically substantiated kinetic model of cadmium transport and toxicity in intestinal cell model (Caco-2 cells). Transcriptome profiling of Caco-2 cells revealed high content of transporter DMT1 and ZIP14 and intensive expression of some calcium channels of the CACN family. The mathematical model describing three types of transporters, as well as intracellular cadmium binding with metallothionein and excretion through the basolateral membrane allowed us to construct cadmium uptake and transport curves that approximated the previously obtained experimental data. Using the proposed model, we determined toxic intracellular cadmium concentration leading to cell death and impairing the integrity of cell monolayer and described cadmium transport in this case.

  1. Plasma transport modelling in the inner magnetosphere: effects of magnetic field, electric field and exospheric models

    Directory of Open Access Journals (Sweden)

    A. Woelfflé

    2011-02-01

    Full Text Available A qualitative study is performed on plasma transport modelling in the inner magnetosphere, revealing the significance of a model use choice and its parameterization. First, we examine particle transport using comparative analysis of both magnetic and electric field models. This work reveals that the electric field plays an important role in understanding particle dynamics and the models lead to various results in terms of plasma source, energy and particle trajectory. We then concentrate particularly on proton loss assessment considering the charge exchange phenomenon. For that, models are needed to provide a neutral hydrogen density estimation. So, exospheric models were tested in light of the Dynamics Explorer 1 measurements analysed by Rairden.

  2. Photo-chemical transport modelling of tropospheric ozone: A review

    Science.gov (United States)

    Sharma, Sumit; Sharma, Prateek; Khare, Mukesh

    2017-06-01

    Ground level ozone (GLO), a secondary pollutant having adverse impact on human health, ecology, and agricultural productivity, apart from being a major contributor to global warming, has been a subject matter of several studies. In order to identify appropriate strategies to control GLO levels, accurate assessment and prediction is essential, for which elaborate simulation and modelling is required. Several studies have been undertaken in the past to simulate GLO levels at different scales and for various applications. It is important to evaluate these studies, widely spread over in literature. This paper aims to critically review various studies that have been undertaken, especially in the past 15 years (2000-15) to model GLO. The review has been done of the studies that range over different spatial scales - urban to regional and continental to global. It also includes a review of performance evaluation and sensitivity analysis of photo-chemical transport models in order to assess the extent of application of these models and their predictive capability. The review indicates following major findings: (a) models tend to over-estimate the night-time GLO concentrations due to limited titration of GLO with NO within the model; (b) dominance of contribution from far-off regional sources to average ozone concentration in the urban region and higher contribution of local sources during days of high ozone episodes; requiring strategies for controlling precursor emissions at both regional and local scales; (c) greater influence of NOx over VOC in export of ozone from urban regions due to shifting of urban plumes from VOC-sensitive regime to NOx-sensitive as they move out from city centres to neighbouring rural regions; (d) models with finer resolution inputs perform better to a certain extent, however, further improvement in resolutions (beyond 10 km) did not show improvement always; (e) future projections show an increase in GLO concentrations mainly due to rise in

  3. Compendium of Material Composition Data for Radiation Transport Modeling

    Energy Technology Data Exchange (ETDEWEB)

    McConn, Ronald J.; Gesh, Christopher J.; Pagh, Richard T.; Rucker, Robert A.; Williams III, Robert

    2011-03-04

    Introduction Meaningful simulations of radiation transport applications require realistic definitions of material composition and densities. When seeking that information for applications in fields such as homeland security, radiation shielding and protection, and criticality safety, researchers usually encounter a variety of materials for which elemental compositions are not readily available or densities are not defined. Publication of the Compendium of Material Composition Data for Radiation Transport Modeling, Revision 0, in 2006 was the first step toward mitigating this problem. Revision 0 of this document listed 121 materials, selected mostly from the combined personal libraries of staff at the Pacific Northwest National Laboratory (PNNL), and thus had a scope that was recognized at the time to be limited. Nevertheless, its creation did provide a well-referenced source of some unique or hard-to-define material data in a format that could be used directly in radiation transport calculations being performed at PNNL. Moreover, having a single common set of material definitions also helped to standardize at least one aspect of the various modeling efforts across the laboratory by providing separate researchers the ability to compare different model results using a common basis of materials. The authors of the 2006 compendium understood that, depending on its use and feedback, the compendium would need to be revised to correct errors or inconsistencies in the data for the original 121 materials, as well as to increase (per users suggestions) the number of materials listed. This 2010 revision of the compendium has accomplished both of those objectives. The most obvious change is the increased number of materials from 121 to 372. The not-so-obvious change is the mechanism used to produce the data listed here. The data listed in the 2006 document were compiled, evaluated, entered, and error-checked by a group of individuals essentially by hand, providing no library

  4. A finite element model for protein transport in vivo

    Directory of Open Access Journals (Sweden)

    Montas Hubert J

    2007-06-01

    Full Text Available Abstract Background Biological mass transport processes determine the behavior and function of cells, regulate interactions between synthetic agents and recipient targets, and are key elements in the design and use of biosensors. Accurately predicting the outcomes of such processes is crucial to both enhancing our understanding of how these systems function, enabling the design of effective strategies to control their function, and verifying that engineered solutions perform according to plan. Methods A Galerkin-based finite element model was developed and implemented to solve a system of two coupled partial differential equations governing biomolecule transport and reaction in live cells. The simulator was coupled, in the framework of an inverse modeling strategy, with an optimization algorithm and an experimental time series, obtained by the Fluorescence Recovery after Photobleaching (FRAP technique, to estimate biomolecule mass transport and reaction rate parameters. In the inverse algorithm, an adaptive method was implemented to calculate sensitivity matrix. A multi-criteria termination rule was developed to stop the inverse code at the solution. The applicability of the model was illustrated by simulating the mobility and binding of GFP-tagged glucocorticoid receptor in the nucleoplasm of mouse adenocarcinoma. Results The numerical simulator shows excellent agreement with the analytic solutions and experimental FRAP data. Detailed residual analysis indicates that residuals have zero mean and constant variance and are normally distributed and uncorrelated. Therefore, the necessary and sufficient criteria for least square parameter optimization, which was used in this study, were met. Conclusion The developed strategy is an efficient approach to extract as much physiochemical information from the FRAP protocol as possible. Well-posedness analysis of the inverse problem, however, indicates that the FRAP protocol provides insufficient

  5. Development of an Integrated Nonlinear Aeroservoelastic Flight Dynamic Model of the NASA Generic Transport Model

    Science.gov (United States)

    Nguyen, Nhan; Ting, Eric

    2018-01-01

    This paper describes a recent development of an integrated fully coupled aeroservoelastic flight dynamic model of the NASA Generic Transport Model (GTM). The integrated model couples nonlinear flight dynamics to a nonlinear aeroelastic model of the GTM. The nonlinearity includes the coupling of the rigid-body aircraft states in the partial derivatives of the aeroelastic angle of attack. Aeroservoelastic modeling of the control surfaces which are modeled by the Variable Camber Continuous Trailing Edge Flap is also conducted. The R.T. Jones' method is implemented to approximate unsteady aerodynamics. Simulations of the GTM are conducted with simulated continuous and discrete gust loads..

  6. Modeling the Influence of Hemispheric Transport on Trends in ...

    Science.gov (United States)

    We describe the development and application of the hemispheric version of the CMAQ to examine the influence of long-range pollutant transport on trends in surface level O3 distributions. The WRF-CMAQ model is expanded to hemispheric scales and multi-decadal model simulations were recently performed for the period spanning 1990-2010 to examine changes in hemispheric air pollution resulting from changes in emissions over this period. Simulated trends in ozone and precursor species concentrations across the U.S. and the northern hemisphere over the past two decades are compared with those inferred from available measurements during this period. Additionally, the decoupled direct method (DDM) in CMAQ is used to estimate the sensitivity of O3 to emissions from different source regions across the northern hemisphere. The seasonal variations in source region contributions to background O3 is then estimated from these sensitivity calculations and will be discussed. A reduced form model combining these source region sensitivities estimated from DDM with the multi-decadal simulations of O3 distributions and emissions trends, is then developed to characterize the changing contributions of different source regions to background O3 levels across North America. The National Exposure Research Laboratory (NERL) Computational Exposure Division (CED) develops and evaluates data, decision-support tools, and models to be applied to media-specific or receptor-specific problem areas

  7. High-temperature transport in the Hubbard Model

    Science.gov (United States)

    Shastry, B. Sriram; Perepelitsky, Edward; Galatas, Andrew; Khatami, Ehsan; Mravlje, Jernej; Georges, Antoine

    We examine the general behavior of the frequency and momentum dependent single-particle scattering rate and the transport coefficients, of many-body systems in the high-temperature limit. We find that the single-particle scattering rate always saturates in temperature, while the transport coefficients always decay like 1/T, where T is the temperature. A consequence of this is a resistivity which is ubiquitously linear in T at high temperatures. For the Hubbard model, by using the high-temperature series, we are able to calculate the first few moments of the single particle scattering rate Σ (k --> , ω) and the conductivity σ (k --> , ω) in the high-temperature regime in d spatial dimensions. Further in the case of d --> ∞ , we are able to calculate a large number of moments using symbolic computation. We make a direct comparison between these moments and those obtained through Dynamical Mean Field Theory (DMFT). Finally, we use the moments to reconstruct the ω-dependent optical conductivity σ (ω) =limk-->0 σ (k --> , ω) in the high-temperature regime. The work at UCSC was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES) under Award # FG02-06ER46319.

  8. Model for Charge Transport in Ferroelectric Nanocomposite Film

    Directory of Open Access Journals (Sweden)

    Meng H. Lean

    2015-01-01

    Full Text Available This paper describes 3D particle-in-cell simulation of charge injection and transport through nanocomposite film comprised of ferroelectric ceramic nanofillers in an amorphous polymer matrix and/or semicrystalline ferroelectric polymer with varying degrees of crystallinity. The classical electrical double layer model for a monopolar core is extended to represent the nanofiller/nanocrystallite by replacing it with a dipolar core. Charge injection at the electrodes assumes metal-polymer Schottky emission at low to moderate fields and Fowler-Nordheim tunneling at high fields. Injected particles propagate via field-dependent Poole-Frenkel mobility. The simulation algorithm uses a boundary integral equation method for solution of the Poisson equation coupled with a second-order predictor-corrector scheme for robust time integration of the equations of motion. The stability criterion of the explicit algorithm conforms to the Courant-Friedrichs-Levy limit assuring robust and rapid convergence. Simulation results for BaTiO3 nanofiller in amorphous polymer matrix and semicrystalline PVDF with varying degrees of crystallinity indicate that charge transport behavior depends on nanoparticle polarization with antiparallel orientation showing the highest conduction and therefore the lowest level of charge trapping in the interaction zone. Charge attachment to nanofillers and nanocrystallites increases with vol% loading or degree of crystallinity and saturates at 30–40 vol% for the set of simulation parameters.

  9. Structural Health Monitoring of Transport Aircraft with Fuzzy Logic Modeling

    Directory of Open Access Journals (Sweden)

    Ray C. Chang

    2013-01-01

    Full Text Available A structural health monitoring method based on the concept of static aeroelasticity is presented in this paper. This paper focuses on the estimation of these aeroelastic effects on older transport aircraft, in particular the structural components that are most affected, in severe atmospheric turbulence. Because the structural flexibility properties are mostly unknown to aircraft operators, only the trend, not the magnitude, of these effects is estimated. For this purpose, one useful concept in static aeroelastic effects for conventional aircraft structures is that under aeroelastic deformation the aerodynamic center should move aft. This concept is applied in the present paper by using the fuzzy-logic aerodynamic models. A twin-jet transport aircraft in severe atmospheric turbulence involving plunging motion is examined. It is found that the pitching moment derivatives in cruise with moderate to severe turbulence in transonic flight indicate some degree of abnormality in the stabilizer (i.e., the horizontal tail. Therefore, the horizontal tail is the most severely affected structural component of the aircraft probably caused by vibration under the dynamic loads induced by turbulence.

  10. Cosmic Ray Transport with Magnetic Focusing and the ``Telegraph'' model

    Science.gov (United States)

    Sagdeev, Roald; Malkov, Mikhail

    2015-11-01

    Cosmic rays (CR), scattered by MHD waves, must propagate diffusively. However, because some of the particles diffuse unrealistically fast, an alternative CR transport model based on the ``telegraph'' equation was put forward. Though, its derivations often lack rigor and transparency leading to inconsistent results. We apply the Chapman-Enskog method to the CR transport. No ``telegraph'' ∂2 f / ∂t2 term emerges in a proper t >> 1 asymptotic expansion. Nevertheless, this term may be converted from the ∂4 f / ∂z4 term of that expansion. However, both the telegraph and hyperdiffusive terms are important only for a short relaxation period associated with the initial CR anisotropy/inhomogeneity. Then, the system evolves diffusively in both cases. The term conversion is possible only after this relaxation period. During this period, the telegraph solution is argued to be unphysical. Unlike the hyperdiffusion correction, it is not uniformly valid and introduces implausible singular components to the solution. These dominate the solution during the relaxation period. Because they are shown not to be inherent in the underlying scattering problem, the telegraph term is involuntarily acquired in an asymptotic reduction. Supported by NASA ATP-program under the grant NNX14AH36G.

  11. Active patterning and asymmetric transport in a model actomyosin network

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shenshen [Department of Chemical Engineering and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Wolynes, Peter G. [Department of Chemistry and Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005 (United States)

    2013-12-21

    Cytoskeletal networks, which are essentially motor-filament assemblies, play a major role in many developmental processes involving structural remodeling and shape changes. These are achieved by nonequilibrium self-organization processes that generate functional patterns and drive intracellular transport. We construct a minimal physical model that incorporates the coupling between nonlinear elastic responses of individual filaments and force-dependent motor action. By performing stochastic simulations we show that the interplay of motor processes, described as driving anti-correlated motion of the network vertices, and the network connectivity, which determines the percolation character of the structure, can indeed capture the dynamical and structural cooperativity which gives rise to diverse patterns observed experimentally. The buckling instability of individual filaments is found to play a key role in localizing collapse events due to local force imbalance. Motor-driven buckling-induced node aggregation provides a dynamic mechanism that stabilizes the two-dimensional patterns below the apparent static percolation limit. Coordinated motor action is also shown to suppress random thermal noise on large time scales, the two-dimensional configuration that the system starts with thus remaining planar during the structural development. By carrying out similar simulations on a three-dimensional anchored network, we find that the myosin-driven isotropic contraction of a well-connected actin network, when combined with mechanical anchoring that confers directionality to the collective motion, may represent a novel mechanism of intracellular transport, as revealed by chromosome translocation in the starfish oocyte.

  12. Development of a prototype land use model for statewide transportation planning activities : summary.

    Science.gov (United States)

    2011-01-01

    Developing computer models of land use and : integrated transportation-land use are high : priorities for Florida transportation planners. : Land use information is fundamental to siting : roadways, signaling, setting maintenance : priorities, routin...

  13. A Nonlinear Dynamic Inversion Predictor-Based Model Reference Adaptive Controller for a Generic Transport Model

    Science.gov (United States)

    Campbell, Stefan F.; Kaneshige, John T.

    2010-01-01

    Presented here is a Predictor-Based Model Reference Adaptive Control (PMRAC) architecture for a generic transport aircraft. At its core, this architecture features a three-axis, non-linear, dynamic-inversion controller. Command inputs for this baseline controller are provided by pilot roll-rate, pitch-rate, and sideslip commands. This paper will first thoroughly present the baseline controller followed by a description of the PMRAC adaptive augmentation to this control system. Results are presented via a full-scale, nonlinear simulation of NASA s Generic Transport Model (GTM).

  14. Uraniam hydrogeochemical and stream sediment reconnaissance of the Wiseman NTMS Quadrangle, Alaska

    Energy Technology Data Exchange (ETDEWEB)

    1981-09-01

    This report presents results of a Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) of the Wiseman NTMS quadrangle, Alaska. In addition to this abbreviated data release, more complete data are available to the public in machine-readable form through the Grand Junction Office Information System at Oak Ridge National Laboratory. Presented in this data release are location data, field analyses, and laboratory analyses of several different sample media. For the sake of brevity, many field observations have not been included in this volume. These data are, however, available on the magnetic tape. Appendix A describes the sample media and summarizes the analytical results for each medium. The data were subdivided by one of the Los Alamos National Laboratory (LANL) sorting programs of Zinkl and others (198a) into stream sediment samples.

  15. Uranium hydrogeochemical and stream sediment reconnaissance of the Philip Smith Mountains NTMS quadrangle, Alaska

    Energy Technology Data Exchange (ETDEWEB)

    1981-09-01

    Results of a hydrogeochemical and stream sediment reconnaissance of the Philip Smith Mountains NTMS quadrangle, Alaska are presented. In addition to this abbreviated data release, more complete data are available to the public in machine-readable form. In this data release are location data, field analyses, and laboratory analyses of several different sample media. For the sake of brevity, many field site observations have not been included in this volume. These data are, however, available on the magnetic tape. Appendices A and B describe the sample media and summarize the analytical results for each medium. The data were subsetted by one of the Los Alamos National Laboratory (LANL) sorting programs into groups of stream sediment and lake sediment samples. For each group which contains a sufficient number of observations, statistical tables, tables of raw data, and 1:1000000 scale maps of pertinent elements have been included in this report.

  16. Uranium hydrogeochemical and stream sediment reconnaissance of the Mt. Hayes NTMS quadrangle, Alaska

    Energy Technology Data Exchange (ETDEWEB)

    1981-05-01

    Results of a hydrogeochemical and stream sediment reconnaissance of the Mt. Hayes quadrangle, Alaska, are presented. In addition to this abbreviated data release, more complete data are available to the public in machine-readable form. In this data release are location data, field analyses, and Laboratory analyses of several different sample media. For the sake of brevity, many field site observations have not been included in this volume. These data are, however, available on the magnetic tape. Appendices A to D describe the sample media and summarize the analytical results for each medium. The data were subsetted by one of the Los Alamos National Laboratory (LANL) sorting programs into groups of stream sediment, lake sediment, stream water, lake water, and ground water samples. For each group which contains a sufficient number of observations, statistical tables, tables of raw data, and 1:1000000 scale maps of pertinent elements have been included in this report.

  17. Uranium hydrogeochemical and stream sediment reconnaissance of the Yakutat NTMS quadrangle, Alaska

    Energy Technology Data Exchange (ETDEWEB)

    1981-09-01

    Results of a hydrogeochemical and stream sediment reconnaissance of the Yakutat NTMS quadrangle, Alaska are presented. In addition to this abbreviated data release, more complete data are available to the public in machine-readable form. In this data release are location data, field analyses, and laboratory analyses of several different sample media. For the sake of brevity, many field site observations have not been included in this volume. These data are, however, available on the magnetic tape. Appendices A and B describe the sample media and summarize the analytical results for each medium. The data were subsetted by one of the Los Alamos National Laboratory (LANL) sorting programs into groups of stream sediment and lake sediment samples. For each group which contains a sufficient number of observations, statistical tables, tables of raw data, and 1:1000000 scale maps of pertinent elements have been included in this report.

  18. Models of long-distance transport: how is carrier-dependent auxin transport regulated in the stem?

    Science.gov (United States)

    Renton, Michael; Hanan, Jim; Ferguson, Brett J; Beveridge, Christine A

    2012-05-01

    • This paper presents two models of carrier-dependent long-distance auxin transport in stems that represent the process at different scales. • A simple compartment model using a single constant auxin transfer rate produced similar data to those observed in biological experiments. The effects of different underlying biological assumptions were tested in a more detailed model representing cellular and intracellular processes that enabled discussion of different patterns of carrier-dependent auxin transport and signalling. • The output that best fits the biological data is produced by a model where polar auxin transport is not limited by the number of transporters/carriers and hence supports biological data showing that stems have considerable excess capacity to transport auxin. • All results support the conclusion that auxin depletion following apical decapitation in pea (Pisum sativum) occurs too slowly to be the initial cause of bud outgrowth. Consequently, changes in auxin content in the main stem and changes in polar auxin transport/carrier abundance in the main stem are not correlated with axillary bud outgrowth. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.

  19. Application of gambler's ruin model to sediment transport problems

    Science.gov (United States)

    Tsai, Christina W.; Hsu, Yaowen; Lai, Kung-Chung; Wu, Nai-Kuang

    2014-03-01

    This study applies the gambler's ruin model to simulate sediment transport. First, the model is mathematically formulated to determine the probability of reaching the maximum state of the sediment carrying capacity, and the mean time spent in transient states before reaching the maximum sediment carrying capacity. Experimental data are used to model the sediment movement process given the bedload and the suspended load particles in the water column. The impact of different parameters is discussed under varying flow conditions and varying sediment particle characteristics. The model shows that, as the maximum number of particles increases, the probability that the flow can carry the particles decreases. A smaller particle size is normally associated with a higher probability of reaching the maximum sediment carrying capacity under the same flow condition. It is also found that as the time a particle spends in the water column increases, the probability of the flow maintaining the same number of particles after several sediment particle transitions into different states increases. In the second case study, the effective risk of a given number of sediment particles in the water column reaching the maximum capacity of the water treatment plant in the Shihmen Reservoir Basin in 2008 is modeled. The Xia Yun hydrologic station is selected for the simulation because it is a fully comprehensive hydrologic station and is located near the Shihmen Reservoir. Moreover, a novel approach is used to incorporate uncertainty analysis in the gambler's ruin model: the Perturbance Moments Method (PMM). Results of expected value and one-standard-deviation interval in the number of sediment particles in the water column are acquired.

  20. Multiscale model reduction for shale gas transport in fractured media

    KAUST Repository

    Akkutlu, I. Y.

    2016-05-18

    In this paper, we develop a multiscale model reduction technique that describes shale gas transport in fractured media. Due to the pore-scale heterogeneities and processes, we use upscaled models to describe the matrix. We follow our previous work (Akkutlu et al. Transp. Porous Media 107(1), 235–260, 2015), where we derived an upscaled model in the form of generalized nonlinear diffusion model to describe the effects of kerogen. To model the interaction between the matrix and the fractures, we use Generalized Multiscale Finite Element Method (Efendiev et al. J. Comput. Phys. 251, 116–135, 2013, 2015). In this approach, the matrix and the fracture interaction is modeled via local multiscale basis functions. In Efendiev et al. (2015), we developed the GMsFEM and applied for linear flows with horizontal or vertical fracture orientations aligned with a Cartesian fine grid. The approach in Efendiev et al. (2015) does not allow handling arbitrary fracture distributions. In this paper, we (1) consider arbitrary fracture distributions on an unstructured grid; (2) develop GMsFEM for nonlinear flows; and (3) develop online basis function strategies to adaptively improve the convergence. The number of multiscale basis functions in each coarse region represents the degrees of freedom needed to achieve a certain error threshold. Our approach is adaptive in a sense that the multiscale basis functions can be added in the regions of interest. Numerical results for two-dimensional problem are presented to demonstrate the efficiency of proposed approach. © 2016 Springer International Publishing Switzerland

  1. Reduced Lorenz models for anomalous transport and profile resilience

    DEFF Research Database (Denmark)

    Rypdal, K.; Garcia, Odd Erik

    2007-01-01

    problem is incompatible with finite fluxes through the system in the limit of vanishing diffusion. An alternative formulation leading to the Lorenz equations is proposed, invoking open boundaries and the notion of convective streamers and their back-reaction on the profile gradient, giving rise......The physical basis for the Lorenz equations for convective cells in stratified fluids, and for magnetized plasmas imbedded in curved magnetic fields, are reexamined with emphasis on anomalous transport. It is shown that the Galerkin truncation leading to the Lorenz equations for the closed boundary...... to resilience of the profile. Particular emphasis is put on the diffusionless limit, where these equations reduce to a simple dynamical system depending only on one single forcing parameter. This model is studied numerically, stressing experimentally observable signatures, and some of the perils of dimension...

  2. Modeling molecular effects on plasmon transport: Silver nanoparticles with tartrazine

    Science.gov (United States)

    Arntsen, Christopher; Lopata, Kenneth; Wall, Michael R.; Bartell, Lizette; Neuhauser, Daniel

    2011-02-01

    Modulation of plasmon transport between silver nanoparticles by a yellow fluorophore, tartrazine, is studied theoretically. The system is studied by combining a finite-difference time-domain Maxwell treatment of the electric field and the plasmons with a time-dependent parameterized method number 3 simulation of the tartrazine, resulting in an effective Maxwell/Schrödinger (i.e., classical/quantum) method. The modeled system has three linearly arranged small silver nanoparticles with a radius of 2 nm and a center-to-center separation of 4 nm; the molecule is centered between the second and third nanoparticles. We initiate an x-polarized current on the first nanoparticle and monitor the transmission through the system. The molecule rotates much of the x-polarized current into the y-direction and greatly reduces the overall transmission of x-polarized current.

  3. Simulation of Cell Adhesion using a Particle Transport Model

    Science.gov (United States)

    Chesnutt, Jennifer

    2005-11-01

    An efficient computational method for simulation of cell adhesion through protein binding forces is discussed. In this method, the cells are represented by deformable elastic particles, and the protein binding is represented by a rate equation. The method is first developed for collision and adhesion of two similar cells impacting on each other from opposite directions. The computational method is then applied in a particle-transport model for a cloud of interacting and colliding cells, each of which are represented by particles of finite size. One application might include red blood cells adhering together to form rouleaux, which are chains of red blood cells that are found in different parts of the circulatory system. Other potential applications include adhesion of platelets to a blood vessel wall or mechanical heart valve, which is a precursor of thrombosis formation, or adhesion of cancer cells to organ walls in the lymphatic, circulatory, digestive or pulmonary systems.

  4. Sediment transport modeling using highly resolved Euler-Lagrange LES

    Science.gov (United States)

    Arolla, Sunil; Desjardins, Olivier

    2014-11-01

    We use an explicitly volume-filtered Euler-Lagrange large eddy simulation methodology to investigate the detailed dynamics of turbulent liquid-solid slurry flows through a horizontal pipe. A series of simulations have been performed by varying the superficial liquid velocity to be consistent with the available experimental data by Danielson (2007). From our numerical simulations, the critical deposition velocity below which a static sand bed starts forming is predicted and compared with the experiments. We discuss the dynamics of liquid-solid slurry flow in connection with the Shields diagram. Depending on the Shields number, patterns develop at the surface of the particle bed, in close analogy with patterns discussed in sediment transport research. We also present statistics extracted to evaluate and improve recently proposed RANS based closure modeling ideas in the context of Euler-Euler formalism.

  5. Hydrogeochemical attributes and ground water quality of Ngbo Community in Ohaukwu Area Council, Ebonyi State, Nigeria

    Directory of Open Access Journals (Sweden)

    Omaka Ndukaku Omaka

    2015-01-01

    Full Text Available This study evaluated the hydrogeochemical attributes and quality of groundwater resources in Ngbo, Ohaukwu Area Council of Ebonyi State, Nigeria in order to determine whether boreholes in the area were suitable for potable uses. Eleven groundwater samples were collected from hand-dug boreholes between February and March, 2013. The physiochemical parameters of the samples were then analyzed to determine electrical conductivity, total dissolved solids, total alkalinity, major cations and anions, and trace metals. The quality of these characteristics was evaluated by comparing them to the Nigerian Institute of Standards, the Bureau of Indian Standards and the World Health Organization standards for drinking water quality. Mass abundance of the major ions was in the order of Mg2+ > Ca2+ for cations, Cl- > SO4 2 - > NO3 - > PO4 3 - for anions and Fe > As > Mn > Cu > Zn > Cr > Ni > Pb > Cd for trace metals. Correlation analysis revealed both positive and negative correlations among the parameters. Also, one-way ANOVA tests revealed that no significant differences existed between physiochemical parameters (F = 1.004 < Fcrit =1.977, major cations and anions (F =0.547 < Fcrit =2.008 and trace metals (F = 0.772 < Fcrit = 1.940 regardless of the sampling location. Groundwater in the area was generally hard, alkaline and highly mineralized, making it unsuitable for drinking in some places due to high total hardness and TDS; but it was generally suitable for irrigation purposes. It is recommended that boreholes be flushed regularly to aid in the removal of mineralized deposits, and that regular hydrogeochemical studies be conducted in order to detect future deterioration of water quality

  6. Hydrogeochemical analysis and evaluation of surface water quality of Pratapgarh district, Uttar Pradesh, India

    Science.gov (United States)

    Tiwari, Ashwani Kumar; Singh, Abhay Kumar; Singh, Amit Kumar; Singh, M. P.

    2017-07-01

    The hydrogeochemical study of surface water in Pratapgarh district has been carried out to assess the major ion chemistry and water quality for drinking and domestic purposes. For this purpose, twenty-five surface water samples were collected from river, ponds and canals and analysed for pH, electrical conductivity, total dissolved solids (TDS), turbidity, hardness, major cations (Ca2+, Mg2+, Na+ and K+), major anions (HCO3 -, F-, Cl-, NO3 -, SO4 2-) and dissolved silica concentration. The analytical results show mildly acidic to alkaline nature of surface water resources of Pratapgarh district. HCO3 - and Cl- are the dominant anions, while cation chemistry is dominated by Na+ and Ca2+. The statistical analysis and data plotted on the Piper diagram reveals that the surface water chemistry is mainly controlled by rock weathering with secondary contributions from agriculture and anthropogenic sources. Ca2+-Mg2+-HCO3 -, Ca2+-Mg2+-Cl- and Na+-HCO3 --Cl- are the dominant hydrogeochemical facies in the surface water of the area. For quality assessment, values of analysed parameters were compared with Indian and WHO water quality standards, which shows that the concentrations of TDS, F-, NO3 -, Na+, Mg2+ and total hardness are exceeding the desirable limits in some water samples. Water Quality Index (WQI) is one of the most effective tools to communicate information on the quality of any water body. The computed WQI values of Pratapgarh district surface water range from 28 to 198 with an average value of 82, and more than half of the study area is under excellent to good category.

  7. Hydrogeochemical signatures of thermal springs compared to deep formation water of North Germany

    Science.gov (United States)

    Bozau, Elke; van Berk, Wolfgang

    2014-05-01

    Thermal springs and hot deep formation waters can be used for geothermal energy production. Depending on the chemical composition of the used waters, geothermal power plants have to deal with scaling and corrosion effects. Therefore, the understanding of the hydrogeochemical behaviour of such waters can be helpful to enhance the efficiency of the energy production. This study is comparing hydrogeochemical characteristics of thermal springs in the Harz Mountains (North Germany) and deep formation water of the North German Basin. The Harz Mountains consist of uplifted Palaeozoic rocks, whereas the North German Basin consists of sedimentary layers of Permian, Mesozoic and Cenozoic age. Volcanic rocks are included in the Permian layers. The thickness of the sedimentary basin varies between 2 km and more than 8 km. The deep aquifers of the North German Basin are mostly not involved in the recent meteoric water cycle. Their waters have contents of Total Dissolved Solids (TDS) up to about 400 g/L. Thermal springs of the Harz Mountains are situated close to the main fracture system of the region. These springs are connected to the meteoric water cycle and display lower contents of TDS (Harz Mountains and the North German Basin. The concentrations of calcium, sodium, and chloride differ due to salt dissolution and feldspar transformation (albitisation) in the thermal springs as well as in the deep formation waters. Based on today's knowledge hydrochemical and stratigraphical data from the North German Basin can be used to elucidate the geological origin of the thermal springs in the Harz Mountains. Acknowledgements. The presented data are results of the collaborative research program "gebo" (Geothermal energy and high performance drilling), financed by the Ministry of Science and Culture of the State of Lower Saxony and the company Baker Hughes.

  8. Longshore sediment transport model for the Indian west coast

    Digital Repository Service at National Institute of Oceanography (India)

    Chandramohan, P.; Nayak, B.U.

    Longshore sediment transport rates for the Indian west coast from Cochin to Porbandar are estimated from ship observed wave data (1968 to 1986). The sediment transport rate is relatively high during the southwest monsoon period from June...

  9. Modeling of sediment transport along Mangalore coast using mike 21

    Digital Repository Service at National Institute of Oceanography (India)

    Babu, K.S.; Dwarakish, G.S.; Jayakumar, S.

    The objective of the present study is to understand the sediment transport along Mangalore Coast and to quantify the sediment transport rates. The data used in the present study includes Wave, Wind, Tide, Naval Hydrographic Chart (Bathymetry Chart...

  10. Hypernetwork generation for multi-modal transportation system modeling.

    Science.gov (United States)

    2013-04-01

    The transportation debate has evolved in recent decades to include ideas such as sustainability and livability alongside mobility and safety. Definitional complexities aside, there is no doubt that this evolution has created a national transportation...

  11. A simulation model for intermodal freight transportation in Louisiana.

    Science.gov (United States)

    2015-01-01

    With increased emphasis on intermodal transportation development, the issue of how to evaluate an intermodal freight transportation system and provide intermodal solutions has been receiving intensive attention. In order to improve freight flow effic...

  12. Critical review: Radionuclide transport, sediment transport, and water quality mathematical modeling; and radionuclide adsorption/desorption mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Onishi, Y.; Serne, R.J.; Arnold, E.M.; Cowan, C.E.; Thompson, F.L. [Pacific Northwest Lab., Richland, WA (United States)

    1981-01-01

    This report describes the results of a detailed literature review of radionuclide transport models applicable to rivers, estuaries, coastal waters, the Great Lakes, and impoundments. Some representatives sediment transport and water quality models were also reviewed to evaluate if they can be readily adapted to radionuclide transport modeling. The review showed that most available transport models were developed for dissolved radionuclide in rivers. These models include the mechanisms of advection, dispersion, and radionuclide decay. Since the models do not include sediment and radionuclide interactions, they are best suited for simulating short-term radionuclide migration where: (1) radionuclides have small distribution coefficients; (2) sediment concentrations in receiving water bodies are very low. Only 5 of the reviewed models include full sediment and radionuclide interactions: CHMSED developed by Fields; FETRA SERATRA, and TODAM developed by Onishi et al, and a model developed by Shull and Gloyna. The 5 models are applicable to cases where: (1) the distribution coefficient is large; (2) sediment concentrations are high; or (3) long-term migration and accumulation are under consideration. The report also discusses radionuclide absorption/desorption distribution ratios and addresses adsorption/desorption mechanisms and their controlling processes for 25 elements under surface water conditions. These elements are: Am, Sb, C, Ce, Cm, Co, Cr, Cs, Eu, I, Fe, Mn, Np, P, Pu, Pm, Ra, Ru, Sr, Tc, Th, {sup 3}H, U, Zn and Zr.

  13. Transportes

    Directory of Open Access Journals (Sweden)

    Hidalgo Fernández-Cano, Amalio

    1960-01-01

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

  14. Modelling sailing time and cost for inland waterway transport

    NARCIS (Netherlands)

    Hekkenberg, R.G.; van Dorsser, J.C.M.; Schweighofer, Juha

    2017-01-01

    Transport time and cost are decisive factors for shippers when they choose a mode for their transport. For inland waterway transport in particular, these aspects are more uncertain and less easy to generalize than for road and rail. This is due to the highly variable waterway conditions on

  15. A Comprehensive Numerical Model for Simulating Fluid Transport in Nanopores

    Science.gov (United States)

    Zhang, Yuan; Yu, Wei; Sepehrnoori, Kamy; di, Yuan

    2017-01-01

    Since a large amount of nanopores exist in tight oil reservoirs, fluid transport in nanopores is complex due to large capillary pressure. Recent studies only focus on the effect of nanopore confinement on single-well performance with simple planar fractures in tight oil reservoirs. Its impacts on multi-well performance with complex fracture geometries have not been reported. In this study, a numerical model was developed to investigate the effect of confined phase behavior on cumulative oil and gas production of four horizontal wells with different fracture geometries. Its pore sizes were divided into five regions based on nanopore size distribution. Then, fluid properties were evaluated under different levels of capillary pressure using Peng-Robinson equation of state. Afterwards, an efficient approach of Embedded Discrete Fracture Model (EDFM) was applied to explicitly model hydraulic and natural fractures in the reservoirs. Finally, three fracture geometries, i.e. non-planar hydraulic fractures, non-planar hydraulic fractures with one set natural fractures, and non-planar hydraulic fractures with two sets natural fractures, are evaluated. The multi-well performance with confined phase behavior is analyzed with permeabilities of 0.01 md and 0.1 md. This work improves the analysis of capillarity effect on multi-well performance with complex fracture geometries in tight oil reservoirs.

  16. Elastic Network Model of a Nuclear Transport Complex

    Science.gov (United States)

    Ryan, Patrick; Liu, Wing K.; Lee, Dockjin; Seo, Sangjae; Kim, Young-Jin; Kim, Moon K.

    2010-05-01

    The structure of Kap95p was obtained from the Protein Data Bank (www.pdb.org) and analyzed RanGTP plays an important role in both nuclear protein import and export cycles. In the nucleus, RanGTP releases macromolecular cargoes from importins and conversely facilitates cargo binding to exportins. Although the crystal structure of the nuclear import complex formed by importin Kap95p and RanGTP was recently identified, its molecular mechanism still remains unclear. To understand the relationship between structure and function of a nuclear transport complex, a structure-based mechanical model of Kap95p:RanGTP complex is introduced. In this model, a protein structure is simply modeled as an elastic network in which a set of coarse-grained point masses are connected by linear springs representing biochemical interactions at atomic level. Harmonic normal mode analysis (NMA) and anharmonic elastic network interpolation (ENI) are performed to predict the modes of vibrations and a feasible pathway between locked and unlocked conformations of Kap95p, respectively. Simulation results imply that the binding of RanGTP to Kap95p induces the release of the cargo in the nucleus as well as prevents any new cargo from attaching to the Kap95p:RanGTP complex.

  17. The PDF Approach for Modelling Particle Transport in Turbulent Flows

    Science.gov (United States)

    Reeks, Michael

    2004-11-01

    The Probabaility Density (PDF) approach for modelling dispersed particle flow is analogous to the classical kinetic theory gases. That is, there exists a master equation (analogous to the Maxwell Boltzmann equation of Kinetic Theory) which can be used in a formal way to derive the two-fluid model equations for both phases of the flow and the associated constitutive relations. In addition the approach deals with the near wall behaviour, incorporating the natural boundary conditions of the flow. There are currently two forms of pdf approach: the first form is similar to kinetic theory in that the pdf P(v,x,t) refers to particle velocity v and position x at time t; a second approach in which the pdf P(v,u,x,t) involves the carrier flow velocity u encountered by a particle based on a generalised Langevin equation. Both approaches deal with both dilute and dense particle flows: the influence of inter-particle collisions is directly analogous to the treatment of molecular collisions in kinetic theory. This presentation will describe how each PDF master equation is derived and the form of the closure approximations for the turbulent fluxes. The form of the continuum equations and constitutive relations derived from these equations will be presented and contrasted and the treatment of near wall behaviour briefly discussed. Validation of these approaches for homogeneous and simple shear flows will be given as well as model predictions for a number of test cases involving transport of particles in non-uniform flows.

  18. A model for development of freight transport; En model for godstransportens udvikling

    Energy Technology Data Exchange (ETDEWEB)

    Kveiborg, O. [National Environmental Res., Systems Analysis Dept. Roskilde (Denmark)

    2001-01-01

    This report describes the results of a large project conducted in a corporation between Statistics Denmark and the Danish National Environmental Research Institute. The main objective of the project has been to analyse the possibilities of prescribing the development in the Danish freight transport in a more appropriate and precise way than it is done by existing models. A secondary objective of the project was to develop a model based on the findings of the analysis. The intention was to be able to describe all areas of freight transport. The analysis has proven it impossible to improve the existing calculations in some areas of transport. Hence, the project has been narrowed down to focus exclusively on road freight transport. The developed model distinguishes itself from existing models by a much higher level of detail in the calculations. This enables the model to describe the structural relations between transport and economic activity, which has previously been subsumed in the aggregate calculations of existing models. The work carried out in the process of developing a model for the freight transport has encountered many difficulties. The findings described in this report are merely one step towards a better understanding of the relation between economic development and transport. The descriptions on the following pages will describe some of the difficulties we have had in achieving an appropriate statistical description of the different linkages. Furthermore, the calculations carried out with the model point at other unsolved problems. There is an indication that the model tends to overestimate the developments in freight transport. In this respect, the very disaggregate calculations of the model can be seen as both an advantage and as a disadvantage because each extra calculation gives rise to further uncertainties in the overall result. Even though we have had great difficulties finding adequate descriptions of the development in the factors in the model

  19. Modelling transport and deposition of caesium and iodine from the Chernobyl accident using the DREAM model

    Directory of Open Access Journals (Sweden)

    J. Brandt

    2002-01-01

    Full Text Available A tracer model, DREAM (the Danish Rimpuff and Eulerian Accidental release Model, has been developed for modelling transport, dispersion and deposition (wet and dry of radioactive material from accidental releases, as the Chernobyl accident. The model is a combination of a Lagrangian model, that includes the near source dispersion, and an Eulerian model describing the long-range transport. The performance of the transport model has previously been tested within the European Tracer Experiment, ETEX, which included transport and dispersion of an inert, non-depositing tracer from a controlled release. The focus of this paper is the model performance with respect to the total deposition of  137Cs, 134Cs and 131I from the Chernobyl accident, using different relatively simple and comprehensive parameterizations for dry- and wet deposition. The performance, compared to measurements, of using different combinations of two different wet deposition parameterizations and three different parameterizations of dry deposition has been evaluated, using different statistical tests. The best model performance, compared to measurements, is obtained when parameterizing the total deposition combined of a simple method for dry deposition and a subgrid-scale averaging scheme for wet deposition based on relative humidities. The same major conclusion is obtained for all the three different radioactive isotopes and using two different deposition measurement databases. Large differences are seen in the results obtained by using the two different parameterizations of wet deposition based on precipitation rates and relative humidities, respectively. The parameterization based on subgrid-scale averaging is, in all cases, performing better than the parameterization based on precipitation rates. This indicates that the in-cloud scavenging process is more important than the below cloud scavenging process for the submicron particles and that the precipitation rates are

  20. Nitrogen Risk Assessment Model for Scotland: II. Hydrological transport and model testing

    Directory of Open Access Journals (Sweden)

    S. M. Dunn

    2004-01-01

    Full Text Available The amount and concentration of N in catchment runoff is strongly controlled by a number of hydrological influences, such as leaching rates and the rate of transport of N from the land to surface water bodies. This paper describes how the principal hydrological controls at a catchment scale have been represented within the Nitrogen Risk Assessment Model for Scotland (NIRAMS; it demonstrates their influence through application of the model to eight Scottish catchments, contrasting in terms of their land use, climate and topography. Calculation of N leaching rates, described in the preceding paper (Dunn et al., 2004, is based on soil water content determined by application of a weekly water balance model. This model uses national scale datasets and has been developed and applied to the whole of Scotland using five years of historical meteorological data. A catchment scale transport model, constructed from a 50m digital elevation model, routes flows of N through the sub-surface and groundwater to the stream system. The results of the simulations carried out for eight different catchments demonstrate that the NIRAMS model is capable of predicting time-series of weekly stream flows and N concentrations, to an acceptable degree of accuracy. The model provides an appropriate framework for risk assessment applications requiring predictions in ungauged catchments and at a national scale. Analysis of the model behaviour shows that streamwater N concentrations are controlled both by the rate of supply of N from leaching as well as the rate of transport of N from the land to the water. Keywords: nitrogen, diffuse pollution, hydrology, model, transport, catchment

  1. Predicted congestions never occur. On the gap between transport modeling and human behavior

    Directory of Open Access Journals (Sweden)

    Harald FREY

    2011-01-01

    Full Text Available This paper presents an introduction to meso-scale transport modeling and issues of human behaviour in transport systems. Along with other examples of the human ability to learn in transport systems we look at the comparison of real life data and the prediction of modeling tools for the closure of Vienna’s inner ring road during the 2008 European Football Championship (EURO 2008. Some light is shed on the scientific question, whether currently used modeling tools are able to adequately reproduce the real-life behaviour of human beings in the transport system and should be used for transport policy decision making.

  2. Explaining Air and Water Transport in Undisturbed Soils By X-Ray CT Derived Macroporosity and CT- Number-Derived Matrix Density

    DEFF Research Database (Denmark)

    Paradelo Pérez, Marcos; Katuwal, Sheela; Møldrup, Per

    The characterization of soil pore space geometry is important to predict the fluxes of air, water and solutes through soil and understand soil hydrogeochemical functions. X-ray computed tomography (CT) -derived parameters were evaluated as predictors of water, air and solute transport through soil...... CTmatrix and limiting macroporosity, while the best model for t0.05 used only CTmatrix. The resolution of the scanning and the time for soil structure development after mechanical activities can be factors that increased the uncertainty of the proposed models. Nevertheless, the results confirmed....... Forty five soil columns (20-cm × 20-cm) were collected at an agricultural field in Estrup, Denmark. The soil columns were scanned in a medical CT-scanner. Subsequent to this, non-reactive tracer leaching experiments were performed in the laboratory together with measurements of air permeability (Ka...

  3. Modelling and evaluation of optical WDM transport networks

    Science.gov (United States)

    Wauters, Nico

    1997-10-01

    In this PhD thesis optical WDM transport networks are investigated that use novel optical components to transmit simultaneously multiple datasignals using WDM and which route in their nodes incoming datasignals to one of the outlet fibers without converting these signals to the electrical domain. The goal of the thesis is twofold. On the one hand developing new models that lead to a classification of components, nodes, network architectures and network management techniques such as monitoring and signalling. On the other hand to investigate to which extent wavelength convertors are required for an optimal use of the available wavelength channels. At the same time the tuneability of the WDM terminal multiplexers is questioned. Part 1 gives a general introduction to optical transmission and network techniques by an extensive study of the literature and a limited market survey. In part 2 we propose a number of new models to represent WDM networks and their main building blocks. This leads to a black box model and a classification of all the OXC architectures. Secondly we extend the G.803 layer structure with new layers allowing the representation of hybrid WDM and SDH networks. Finally the model is used to classify different signalling and monitoring options that can be followed. In part 3 we investigate the requirement of wavelength convertors and the tuneability of the WDM terminal multiplexers. The main conclusion of this part is that wavelength translation is not a conditio sine qua non to achieve low blocking probabilities. This contrasts to the much larger difference that appeared between WPa and WPb and which allowed us to conclude that tuneability of the WDM terminal multiplexers is thoroughly required. We do not want to disregard other consequences of not using wavelength convertors in the network as e.g., simplified wavelength management in networks with wavelength convertors and the regeneration capabilities of new all- optical wavelength conversion devices.

  4. Computational Model for Oxygen Transport and Consumption in Human Vitreous

    Science.gov (United States)

    Filas, Benjamen A.; Shui, Ying-Bo; Beebe, David C.

    2013-01-01

    Purpose. Previous studies that measured liquefaction and oxygen content in human vitreous suggested that exposure of the lens to excess oxygen causes nuclear cataracts. Here, we developed a computational model that reproduced available experimental oxygen distributions for intact and degraded human vitreous in physiologic and environmentally perturbed conditions. After validation, the model was used to estimate how age-related changes in vitreous physiology and structure alter oxygen levels at the lens. Methods. A finite-element model for oxygen transport and consumption in the human vitreous was created. Major inputs included ascorbate-mediated oxygen consumption in the vitreous, consumption at the posterior lens surface, and inflow from the retinal vasculature. Concentration-dependent relations were determined from experimental human data or estimated from animal studies, with the impact of all assumptions explored via parameter studies. Results. The model reproduced experimental data in humans, including oxygen partial pressure (Po2) gradients (≈15 mm Hg) across the anterior-posterior extent of the vitreous body, higher oxygen levels at the pars plana relative to the vitreous core, increases in Po2 near the lens after cataract surgery, and equilibration in the vitreous chamber following vitrectomy. Loss of the antioxidative capacity of ascorbate increases oxygen levels 3-fold at the lens surface. Homogeneous vitreous degeneration (liquefaction), but not partial posterior vitreous detachment, greatly increases oxygen exposure to the lens. Conclusions. Ascorbate content and the structure of the vitreous gel are critical determinants of lens oxygen exposure. Minimally invasive surgery and restoration of vitreous structure warrant further attention as strategies for preventing nuclear cataracts. PMID:24008409

  5. FEMA: a Finite Element Model of Material Transport through Aquifers

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, G.T.; Huff, D.D.

    1985-01-01

    This report documents the construction, verification, and demonstration of a Finite Element Model of Material Transport through Aquifers (FEMA). The particular features of FEMA are its versatility and flexibility to deal with as many real-world problems as possible. Mechanisms included in FEMA are: carrier fluid advection, hydrodynamic dispersion and molecular diffusion, radioactive decay, sorption, source/sinks, and degradation due to biological, chemical as well as physical processes. Three optional sorption models are embodied in FEMA. These are linear isotherm and Freundlich and Langmuir nonlinear isotherms. Point as well as distributed source/sinks are included to represent artificial injection/withdrawals and natural infiltration of precipitation. All source/sinks can be transient or steady state. Prescribed concentration on the Dirichlet boundary, given gradient on the Neumann boundary segment, and flux at each Cauchy boundary segment can vary independently of each other. The aquifer may consist of as many formations as desired. Either completely confined or completely unconfined or partially confined and partially unconfined aquifers can be dealt with effectively. FEMA also includes transient leakage to or from the aquifer of interest through confining beds from or to aquifers lying below and/or above.

  6. Modeling elements of energy systems for thermal energy transportation

    Directory of Open Access Journals (Sweden)

    Shurygin A. M.

    2016-12-01

    Full Text Available Heating industrial facilities and the residential sector in recent years is the economic and technical challenge. It has been noted that the efficiency of the heat generating equipment depends not only on its sophistication, fuel type, but also on work of the distributing network taking into account the thermal, hydraulic losses, characteristics and modes of use of heating objects – buildings and technological processes. Possibility of supplying maximum heat flow from the heating system considering mismatch of highs and types of resources consumed from individual consumers should be provided by the right choice of energy equipment set, as well as bandwidth of transport systems and possibility of its regulation. It is important not just to configure the system to work effectively in the current mode (usually at the maximum load, but in the entire load range, as the calculated mode often takes a relatively small portion of the operating time. Thus, the efficiency of heating systems is largely determined by the method used for its control, including the possibility of regulating the main units and elements of the system. The paper considers the factors affecting the system efficiency. Mathematical models of the system elements allowing adjust the amount of released heat energy for consumers have been presented. Separately the mathematical model of the control system of electric drive vehicles used in the system has been considered and implemented.

  7. Modeling marine surface microplastic transport to assess optimal removal locations

    Science.gov (United States)

    Sherman, Peter; van Sebille, Erik

    2016-01-01

    Marine plastic pollution is an ever-increasing problem that demands immediate mitigation and reduction plans. Here, a model based on satellite-tracked buoy observations and scaled to a large data set of observations on microplastic from surface trawls was used to simulate the transport of plastics floating on the ocean surface from 2015 to 2025, with the goal to assess the optimal marine microplastic removal locations for two scenarios: removing the most surface microplastic and reducing the impact on ecosystems, using plankton growth as a proxy. The simulations show that the optimal removal locations are primarily located off the coast of China and in the Indonesian Archipelago for both scenarios. Our estimates show that 31% of the modeled microplastic mass can be removed by 2025 using 29 plastic collectors operating at a 45% capture efficiency from these locations, compared to only 17% when the 29 plastic collectors are moored in the North Pacific garbage patch, between Hawaii and California. The overlap of ocean surface microplastics and phytoplankton growth can be reduced by 46% at our proposed locations, while sinks in the North Pacific can only reduce the overlap by 14%. These results are an indication that oceanic plastic removal might be more effective in removing a greater microplastic mass and in reducing potential harm to marine life when closer to shore than inside the plastic accumulation zones in the centers of the gyres.

  8. Mass transport model through the skin by microencapsulation system.

    Science.gov (United States)

    Carreras, Núria; Alonso, Cristina; Martí, Meritxell; Lis, Manel J

    2015-01-01

    Skin drug delivery can be subdivided into topical and transdermal administration. Transdermal administration can take advantage of chemical and physical strategies that can improve skin permeability and allow drug penetration. In this study, the development of a skin penetration profile was carried out by an in vitro technique for a microencapsulated system of ibuprofen. Release experiments were performed using percutaneous absorption tests to determine the evolution of the principle present in each of the different skin compartments as a function of time. A general kinetic model for a microencapsulated structure as a mass transport system through the skin was applied: [Formula: see text] This model could predict the penetration profile of encapsulated substances through skin from biofunctional textiles as well as estimate the dosage profile of the active principle. The apparent diffusion coefficients found were 1.20 × 10(-7 )cm/s for the stratum corneum and higher for the rest of the skin 6.67 × 10(-6 )cm/s.

  9. Computational modeling of multiphase flow and transport with Python

    Science.gov (United States)

    Kees, C. E.; Farthing, M. W.; Hines, A. M.; Howington, S. E.

    2008-12-01

    Computational flow and transport models play an important role in many hydrological investigations. Unfortunately, developing simulators that are efficient, widely applicable, and robust is a challenge. This is particularly true if the target applications include complications like multiple fluid phases with multiple components and material heterogeneity. To be specific, these problems often involve physical phenomena at multiple spatial and temporal scales. The appropriate formulation may evolve, and the systems of partial differential equations (PDEs) that arise from traditional formulations can be hard to solve efficiently at the desired resolution. Here, we discuss the development of a Python-based modeling framework for finite element approximation of systems of nonlinear PDEs with an emphasis on multiphase, multicomponent systems relevant for surface and subsurface hydrology. In addition to the overall approach and application, we consider the role of Python in managing code complexity, providing user interfaces, developing solution algorithms, and implementing numerical methods for execution on serial and parallel platforms. We evaluate trade-offs and design choices that follow from our use of Python versus other languages like C++ or Fortran and consider the impact on performance measured in terms of metrics like memory usage, execution time, and developer time.

  10. Parameter estimation in six numerical models of transperitoneal transport of potassium in patients undergoing peritoneal dialysis

    DEFF Research Database (Denmark)

    Graff, J; Fugleberg, S; Joffe, P

    1995-01-01

    The mechanisms of transperitoneal potassium transport during peritoneal dialysis were evaluated by validation of different mathematical models. The models were designed to elucidate the presence or absence of diffusive, non-lymphatic convective and lymphatic convective solute transport. Experimen......The mechanisms of transperitoneal potassium transport during peritoneal dialysis were evaluated by validation of different mathematical models. The models were designed to elucidate the presence or absence of diffusive, non-lymphatic convective and lymphatic convective solute transport....... Experimental results were obtained from 26 non-diabetic patients undergoing peritoneal dialysis. The validation procedure demonstrated that models including both diffusive and non-lymphatic convective solute transport were superior to the other models. Lymphatic convective solute transport was not identifiable...

  11. Modelling public transport passenger flows in the era of intelligent transport systems COST Action TU1004 (TransITs)

    CERN Document Server

    Noekel, Klaus

    2016-01-01

    This book shows how transit assignment models can be used to describe and predict the patterns of network patronage in public transport systems. It provides a fundamental technical tool that can be employed in the process of designing, implementing and evaluating measures and/or policies to improve the current state of transport systems within given financial, technical and social constraints. The book offers a unique methodological contribution to the field of transit assignment because, moving beyond “traditional” models, it describes more evolved variants that can reproduce: • intermodal networks with high- and low-frequency services; • realistic behavioural hypotheses underpinning route choice; • time dependency in frequency-based models; and • assumptions about the knowledge that users have of network conditions that are consistent with the present and future level of information that intelligent transport systems (ITS) can provide. The book also considers the practical perspective of practit...

  12. Modeling Np and Pu transport with a surface complexation model and spatially variant sorption capacities: Implications for reactive transport modeling and performance assessments of nuclear waste disposal sites

    Science.gov (United States)

    Glynn, P.D.

    2003-01-01

    One-dimensional (1D) geochemical transport modeling is used to demonstrate the effects of speciation and sorption reactions on the ground-water transport of Np and Pu, two redox-sensitive elements. Earlier 1D simulations (Reardon, 1981) considered the kinetically limited dissolution of calcite and its effect on ion-exchange reactions (involving 90Sr, Ca, Na, Mg and K), and documented the spatial variation of a 90Sr partition coefficient under both transient and steady-state chemical conditions. In contrast, the simulations presented here assume local equilibrium for all reactions, and consider sorption on constant potential, rather than constant charge, surfaces. Reardon's (1981) seminal findings on the spatial and temporal variability of partitioning (of 90Sr) are reexamined and found partially caused by his assumption of a kinetically limited reaction. In the present work, sorption is assumed the predominant retardation process controlling Pu and Np transport, and is simulated using a diffuse-double-layer-surface-complexation (DDLSC) model. Transport simulations consider the infiltration of Np- and Pu-contaminated waters into an initially uncontaminated environment, followed by the cleanup of the resultant contamination with uncontaminated water. Simulations are conducted using different spatial distributions of sorption capacities (with the same total potential sorption capacity, but with different variances and spatial correlation structures). Results obtained differ markedly from those that would be obtained in transport simulations using constant Kd, Langmuir or Freundlich sorption models. When possible, simulation results (breakthrough curves) are fitted to a constant K d advection-dispersion transport model and compared. Functional differences often are great enough that they prevent a meaningful fit of the simulation results with a constant K d (or even a Langmuir or Freundlich) model, even in the case of Np, a weakly sorbed radionuclide under the

  13. Geological and hydrogeochemical research, tools for karst management in the north of the Caraş Gorges (Banat Mountains, Romania)

    OpenAIRE

    Marius Vlaicu; Cristian Mihai Munteanu; Constantin Marin; Alin Tudorache

    2010-01-01

    The karst geosystems functioning frequently implies very quick mass and energy transfers, which make them highly sensitive to any natural or anthropogenic disturbance. Therefore, the groundwater resources, threatened by agricultural and industrial pollution, should be carefully exploited, taking into account the intrinsic vulnerability of the region. This paper aims to present the results of the geological, geomorphological and hydrogeochemical studies carried out in the Banat Mountains (Roma...

  14. Modelling debris transport within glaciers by advection in a full-Stokes ice flow model

    Science.gov (United States)

    Wirbel, Anna; Jarosch, Alexander H.; Nicholson, Lindsey

    2017-04-01

    As mountain glaciers recede worldwide, an increasing proportion of the remaining glacierized area is expected to become debris covered. The spatio-temporal development of a surface debris cover has profound effects on the glacier behaviour and meltwater generation, yet little is known about how glacier dynamics influence the spatial distribution of an emerging debris cover. Motivated by this lack of understanding, we present a coupled model to simulate advection and resulting deformation of debris features within glaciers. The finite element model developed in python consists of an advection scheme coupled to a full-Stokes ice flow model, using FEniCS as the numerical framework. We show results from numerical tests that demonstrate its suitability to model advection-dominated transport of concentration in a divergence-free velocity field. The capabilities of the coupled model are demonstrated by simulating transport of debris features of different initial size, shape and location through modelled velocity fields of representative mountain glaciers. The results indicate that deformation of initial debris inputs, as a consequence of being transported through the glacier, plays an important role in determining the location and rate of debris emergence at the glacier surface. The presented work lays the foundation for comprehensive simulations of realistic patterns of debris cover, their spatial and temporal variability and the timescales over which debris covers can form.

  15. A Data-Driven Air Transportation Delay Propagation Model Using Epidemic Process Models

    Directory of Open Access Journals (Sweden)

    B. Baspinar

    2016-01-01

    Full Text Available In air transport network management, in addition to defining the performance behavior of the system’s components, identification of their interaction dynamics is a delicate issue in both strategic and tactical decision-making process so as to decide which elements of the system are “controlled” and how. This paper introduces a novel delay propagation model utilizing epidemic spreading process, which enables the definition of novel performance indicators and interaction rates of the elements of the air transportation network. In order to understand the behavior of the delay propagation over the network at different levels, we have constructed two different data-driven epidemic models approximating the dynamics of the system: (a flight-based epidemic model and (b airport-based epidemic model. The flight-based epidemic model utilizing SIS epidemic model focuses on the individual flights where each flight can be in susceptible or infected states. The airport-centric epidemic model, in addition to the flight-to-flight interactions, allows us to define the collective behavior of the airports, which are modeled as metapopulations. In network model construction, we have utilized historical flight-track data of Europe and performed analysis for certain days involving certain disturbances. Through this effort, we have validated the proposed delay propagation models under disruptive events.

  16. Anomalous solute transport in saturated porous media: Relating transport model parameters to electrical and nuclear magnetic resonance properties

    Science.gov (United States)

    Swanson, Ryan D; Binley, Andrew; Keating, Kristina; France, Samantha; Osterman, Gordon; Day-Lewis, Frederick D.; Singha, Kamini

    2015-01-01

    The advection-dispersion equation (ADE) fails to describe commonly observed non-Fickian solute transport in saturated porous media, necessitating the use of other models such as the dual-domain mass-transfer (DDMT) model. DDMT model parameters are commonly calibrated via curve fitting, providing little insight into the relation between effective parameters and physical properties of the medium. There is a clear need for material characterization techniques that can provide insight into the geometry and connectedness of pore spaces related to transport model parameters. Here, we consider proton nuclear magnetic resonance (NMR), direct-current (DC) resistivity, and complex conductivity (CC) measurements for this purpose, and assess these methods using glass beads as a control and two different samples of the zeolite clinoptilolite, a material that demonstrates non-Fickian transport due to intragranular porosity. We estimate DDMT parameters via calibration of a transport model to column-scale solute tracer tests, and compare NMR, DC resistivity, CC results, which reveal that grain size alone does not control transport properties and measured geophysical parameters; rather, volume and arrangement of the pore space play important roles. NMR cannot provide estimates of more-mobile and less-mobile pore volumes in the absence of tracer tests because these estimates depend critically on the selection of a material-dependent and flow-dependent cutoff time. Increased electrical connectedness from DC resistivity measurements are associated with greater mobile pore space determined from transport model calibration. CC was hypothesized to be related to length scales of mass transfer, but the CC response is unrelated to DDMT.

  17. Influence of 3D printing on transport : a theory and experts judgment based conceptual model

    NARCIS (Netherlands)

    Boon, Wouter; Van Wee, Bert

    2017-01-01

    Consumer 3D printing is on the rise and has the potential to significantly change the transport and logistics sector. Current literature on 3D printing and transport studies does not provide a systematic model of the impact of 3D printing on transport and related (policy relevant) areas, such as

  18. Predicting Solar Cycle 25 using Surface Flux Transport Model

    Science.gov (United States)

    Imada, Shinsuke; Iijima, Haruhisa; Hotta, Hideyuki; Shiota, Daiko; Kusano, Kanya

    2017-08-01

    It is thought that the longer-term variations of the solar activity may affect the Earth’s climate. Therefore, predicting the next solar cycle is crucial for the forecast of the “solar-terrestrial environment”. To build prediction schemes for the next solar cycle is a key for the long-term space weather study. Recently, the relationship between polar magnetic field at the solar minimum and next solar activity is intensively discussed. Because we can determine the polar magnetic field at the solar minimum roughly 3 years before the next solar maximum, we may discuss the next solar cycle 3years before. Further, the longer term (~5 years) prediction might be achieved by estimating the polar magnetic field with the Surface Flux Transport (SFT) model. Now, we are developing a prediction scheme by SFT model as a part of the PSTEP (Project for Solar-Terrestrial Environment Prediction) and adapting to the Cycle 25 prediction. The predicted polar field strength of Cycle 24/25 minimum is several tens of percent smaller than Cycle 23/24 minimum. The result suggests that the amplitude of Cycle 25 is weaker than the current cycle. We also try to obtain the meridional flow, differential rotation, and turbulent diffusivity from recent modern observations (Hinode and Solar Dynamics Observatory). These parameters will be used in the SFT models to predict the polar magnetic fields strength at the solar minimum. In this presentation, we will explain the outline of our strategy to predict the next solar cycle and discuss the initial results for Cycle 25 prediction.

  19. Preduction of transport properties of gases using classical nonspherical models

    Energy Technology Data Exchange (ETDEWEB)

    Verlin, J.D.

    1976-01-01

    The general formulation of the classical kinetic theory, which is needed to predict transport properties of gases in situations where the hydrodynamic equations are valid, is reviewed. A rigid convex model of tetrahedral symmetry is used to predict the Senftleben-Beenakker effect of a static magnetic field on the thermal conductivity and viscosity of pure CH/sub 4/, CD/sub 4/ and CF/sub 4/. The parameters of the model are optimized and are found to assume physically reasonable values. The calculations agree with experiment to a degree comparable to that of similar work on diatomic molecules. A generalized scattering cross section, ..gamma.., is defined which can be evaluated exactly for the limiting cases of a spherical soft potential and rigid ovaloids. For a general soft nonspherical interaction of the Kihara type, a suitable approximation for the momentum dependence is made with the following attributes: ..gamma.. reduces to the form for soft sphere and rigid ovaloid in the limits and the resulting matrix elements of the collision operator can be written in terms of the familiar ..cap omega..* integrals. This formulation is used to investigate thermal diffusion in binary isotopic mixtures of CO. Calculations are made in an 80/sup 0/K to 300/sup 0/K range which includes the inversion temperatures for all mixtures studied. Thermal conductivity and diffusion coefficients of CO are also calculated. The parameters of the model can be adjusted to account for the major features of the experimental data. The physical significance of the parameters is discussed. (auth)

  20. Discrete Network Modeling for Field-Scale Flow and Transport Through Porous Media

    National Research Council Canada - National Science Library

    Howington, Stacy

    1997-01-01

    .... Specifically, a stochastic, high-resolution, discrete network model is developed and explored for simulating macroscopic flow and conservative transport through macroscopic porous media Networks...

  1. Application of reactive transport modelling to growth and transport of microorganisms in the capillary fringe

    OpenAIRE

    Hron, Pavel; Jost, Daniel; Bastian, Peter; Gallert, Claudia; Winter, Josef; Ippisch, Olaf

    2014-01-01

    A multicomponent multiphase reactive transport simulator has been developed to facilitate the investigation of a large variety of phenomena in porous media including component transport, diffusion, microbiological growth and decay, cell attachment and detachment and phase exchange. The coupled problem is solved using operator splitting. This approach allows a flexible adaptation of the solution strategy to the concrete problem. Moreover, the individual submodels were optimised to be able to d...

  2. Trans-pacific dust transport: integrated analysis of NASA/CALIPSO and a global aerosol transport model

    Directory of Open Access Journals (Sweden)

    K. Eguchi

    2009-05-01

    Full Text Available Detailed 3-D structures of Trans-Pacific Asian dust transport occurring during 5–15 May 2007 were investigated using the NASA/CALIOP vertical-resolved measurements and a three-dimensional aerosol model (SPRINTARS. Both CALIOP and SPRINTARS dust extinctions showed a good agreement along the way of the transport from the dust source regions across North Pacific into North America. A vertically two-layered dust distribution was observed over the northeastern Pacific and North America. The lower dust layer originated from a dust storm generated in the Gobi Desert on 5 May. It was transported at an altitude of around 4 km MSL and has mixed with Asian anthropogenic air pollutants during the course of transport. The upper dust layer mainly originated from a dust storm that occurred in the Taklimakan Desert 2–3 days after the Gobi dust storm generation. The upper dust cloud was transported in higher altitudes above the major clouds layer during the Trans-Pacific transport. It therefore has remained unmixed with the Asian air pollutants and almost unaffected by wet removal. The decay of its concentration level was small (only one-half after its long-distance transport crossing the Pacific. Our dust budget analysis revealed that the Asian dust flux passing through the longitude plane of 140° E was 2.1 Tg, and one third of that arrived North America. The cases analyzed in this study revealed that, while the Gobi Desert is an important source that can contribute to the long-range dust transport, the Taklimakan Desert appears to be another important source that can contribute to the dust transport occurring particularly at high altitudes.

  3. INFRASTRUCTURE, TRANSPORT COSTS, AND BOSNIA AND HERZEGOVINA'S TRADE: A GRAVITY MODEL APPROACH

    OpenAIRE

    Amir Fejzić; Enes Čovrk

    2016-01-01

    This paper examines the impact of transport infrastructure, as an important determinant of transport costs, on trade between Bosnia and Herzegovina and Bosnia and Herzegovina’s fifteen largest trading partners. The estimation is based on a gravity model and panel data for the years 2005 to 2014. Transport costs have been estimated on the basis of distance, geography and quality of transport infrastructure, as well as on sets of "dummy" variables, such as the impact of borders, language or "du...

  4. Transportation Sector Model of the National Energy Modeling System. Volume 2 -- Appendices: Part 2

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-01-01

    The attachments contained within this appendix provide additional details about the model development and estimation process which do not easily lend themselves to incorporation in the main body of the model documentation report. The information provided in these attachments is not integral to the understanding of the model`s operation, but provides the reader with opportunity to gain a deeper understanding of some of the model`s underlying assumptions. There will be a slight degree of replication of materials found elsewhere in the documentation, made unavoidable by the dictates of internal consistency. Each attachment is associated with a specific component of the transportation model; the presentation follows the same sequence of modules employed in Volume 1. The following attachments are contained in Appendix F: Fuel Economy Model (FEM)--provides a discussion of the FEM vehicle demand and performance by size class models; Alternative Fuel Vehicle (AFV) Model--describes data input sources and extrapolation methodologies; Light-Duty Vehicle (LDV) Stock Model--discusses the fuel economy gap estimation methodology; Light Duty Vehicle Fleet Model--presents the data development for business, utility, and government fleet vehicles; Light Commercial Truck Model--describes the stratification methodology and data sources employed in estimating the stock and performance of LCT`s; Air Travel Demand Model--presents the derivation of the demographic index, used to modify estimates of personal travel demand; and Airborne Emissions Model--describes the derivation of emissions factors used to associate transportation measures to levels of airborne emissions of several pollutants.

  5. A Uranium Bioremediation Reactive Transport Benchmark

    Energy Technology Data Exchange (ETDEWEB)

    Yabusaki, Steven B.; Sengor, Sevinc; Fang, Yilin

    2015-06-01

    A reactive transport benchmark problem set has been developed based on in situ uranium bio-immobilization experiments that have been performed at a former uranium mill tailings site in Rifle, Colorado, USA. Acetate-amended groundwater stimulates indigenous microorganisms to catalyze the reduction of U(VI) to a sparingly soluble U(IV) mineral. The interplay between the flow, acetate loading periods and rates, microbially-mediated and geochemical reactions leads to dynamic behavior in metal- and sulfate-reducing bacteria, pH, alkalinity, and reactive mineral surfaces. The benchmark is based on an 8.5 m long one-dimensional model domain with constant saturated flow and uniform porosity. The 159-day simulation introduces acetate and bromide through the upgradient boundary in 14-day and 85-day pulses separated by a 10 day interruption. Acetate loading is tripled during the second pulse, which is followed by a 50 day recovery period. Terminal electron accepting processes for goethite, phyllosilicate Fe(III), U(VI), and sulfate are modeled using Monod-type rate laws. Major ion geochemistry modeled includes mineral reactions, as well as aqueous and surface complexation reactions for UO2++, Fe++, and H+. In addition to the dynamics imparted by the transport of the acetate pulses, U(VI) behavior involves the interplay between bioreduction, which is dependent on acetate availability, and speciation-controlled surface complexation, which is dependent on pH, alkalinity and available surface complexation sites. The general difficulty of this benchmark is the large number of reactions (74), multiple rate law formulations, a multisite uranium surface complexation model, and the strong interdependency and sensitivity of the reaction processes. Results are presented for three simulators: HYDROGEOCHEM, PHT3D, and PHREEQC.

  6. Real-time capable first principle based modelling of tokamak turbulent transport

    CERN Document Server

    Breton, S; Felici, F; Imbeaux, F; Aniel, T; Artaud, J F; Baiocchi, B; Bourdelle, C; Camenen, Y; Garcia, J

    2015-01-01

    A real-time capable core turbulence tokamak transport model is developed. This model is constructed from the regularized nonlinear regression of quasilinear gyrokinetic transport code output. The regression is performed with a multilayer perceptron neural network. The transport code input for the neural network training set consists of five dimensions, and is limited to adiabatic electrons. The neural network model successfully reproduces transport fluxes predicted by the original quasilinear model, while gaining five orders of magnitude in computation time. The model is implemented in a real-time capable tokamak simulator, and simulates a 300s ITER discharge in 10s. This proof-of-principle for regression based transport models anticipates a significant widening of input space dimensionality and physics realism for future training sets. This aims to provide unprecedented computational speed coupled with first-principle based physics for real-time control and integrated modelling applications.

  7. Mathematical modeling of oxadixyl transport in onion crop soil

    Directory of Open Access Journals (Sweden)

    María José Martínez Cordón

    2015-04-01

    Full Text Available Pesticides used in crop production are the most important source of diffuse pollution to groundwater, and their discharge into surface water may be a contributing factor towards the decline of living resources and the deterioration of ecosystems. In this work, we studied the movement of oxadixyl through soil columns (30 cm length and 14 cm diameter in laboratory conditions using onion soil from Lake Tota (Boyacá, Colombia. A solution of 0.01 M CaCl2, containing a tracer (bromide and oxadixyl was sprayed onto the surface of the soil column, and then simulated rainfall was applied at an intensity of 0.034 cm h-1. After 30 days, and 2.13 relative pore volumes, oxadixyl percentages recovered at the bottom of the column were 92.1%. The oxadixyl experimental elution curve was analyzed using the Stanmod program (inverse problem to obtain transport parameters. The non-equilibrium chemical model described the experimental elution curve well. The tail of the elution curve was particularly well captured. The retardation factor calculated for the fungicide was 3.94 and the partition coefficient, kd, was close to 1 kg L-1, indicating low adsorption in this soil. Under the experimental conditions, it could be concluded that oxadixyl is mobile in this soil, and therefore presents a risk of potential groundwater contamination.

  8. A quasi chemistry-transport model mode for EMAC

    Directory of Open Access Journals (Sweden)

    R. Deckert

    2011-03-01

    Full Text Available A quasi chemistry-transport model mode (QCTM is presented for the numerical chemistry-climate simulation system ECHAM/MESSy Atmospheric Chemistry (EMAC. It allows for a quantification of chemical signals through suppression of any feedback between chemistry and dynamics. Noise would otherwise interfere too strongly. The signal is calculated from the difference of two QCTM simulations, a reference simulation and a sensitivity simulation. In order to avoid the feedbacks, the simulations adopt the following offline chemical fields: (a offline mixing ratios of radiatively active substances enter the radiation scheme, (b offline mixing ratios of nitric acid enter the scheme for re-partitioning and sedimentation from polar stratospheric clouds, (c and offline methane oxidation is the exclusive source of chemical water-vapor tendencies. Any set of offline fields suffices to suppress the feedbacks, though may be inconsistent with the simulation setup. An adequate set of offline climatologies can be produced from a non-QCTM simulation using the setup of the reference simulation. Test simulations reveal the particular importance of adequate offline fields associated with (a. Inconsistencies from (b are negligible when using adequate fields of nitric acid. Acceptably small inconsistencies come from (c, but should vanish for an adequate prescription of chemical water vapor tendencies. Toggling between QCTM and non-QCTM is done via namelist switches and does not require a source code re-compilation.

  9. Validation Analysis of the Shoal Groundwater Flow and Transport Model

    Energy Technology Data Exchange (ETDEWEB)

    A. Hassan; J. Chapman

    2008-11-01

    Environmental restoration at the Shoal underground nuclear test is following a process prescribed by a Federal Facility Agreement and Consent Order (FFACO) between the U.S. Department of Energy, the U.S. Department of Defense, and the State of Nevada. Characterization of the site included two stages of well drilling and testing in 1996 and 1999, and development and revision of numerical models of groundwater flow and radionuclide transport. Agreement on a contaminant boundary for the site and a corrective action plan was reached in 2006. Later that same year, three wells were installed for the purposes of model validation and site monitoring. The FFACO prescribes a five-year proof-of-concept period for demonstrating that the site groundwater model is capable of producing meaningful results with an acceptable level of uncertainty. The corrective action plan specifies a rigorous seven step validation process. The accepted groundwater model is evaluated using that process in light of the newly acquired data. The conceptual model of ground water flow for the Project Shoal Area considers groundwater flow through the fractured granite aquifer comprising the Sand Springs Range. Water enters the system by the infiltration of precipitation directly on the surface of the mountain range. Groundwater leaves the granite aquifer by flowing into alluvial deposits in the adjacent basins of Fourmile Flat and Fairview Valley. A groundwater divide is interpreted as coinciding with the western portion of the Sand Springs Range, west of the underground nuclear test, preventing flow from the test into Fourmile Flat. A very low conductivity shear zone east of the nuclear test roughly parallels the divide. The presence of these lateral boundaries, coupled with a regional discharge area to the northeast, is interpreted in the model as causing groundwater from the site to flow in a northeastward direction into Fairview Valley. Steady-state flow conditions are assumed given the absence of

  10. Modeling and Evaluation of LTE in Intelligent Transportation Systems

    NARCIS (Netherlands)

    Trichias, K.; van den Berg, Hans Leo; de Jongh, J.; Litjens, R.; Dimitrova, D.C.; Brogle, M.; Braun, T.; Heijenk, Gerhard J.; Meratnia, Nirvana

    The term Intelligent Transportation Systems (ITS) refers to adding information and communications technology to transport infrastructure and ve- hicles. The IEEE 802.11p standard is considered the main candidate for com- munication within the context of ITS and it performs well for active safety use

  11. Modeling of capacitated transportation systems for integral scheduling

    NARCIS (Netherlands)

    Ebben, Mark; van der Heijden, Matthijs C.; Hurink, Johann L.; Schutten, Johannes M.J.; Günther, H.O.; Kim, K.H.

    2005-01-01

    Motivated by a planned automated cargo transportation network, we consider transportation problems in which the finite capacity of resources (such as vehicles, docks, parking places) has to be taken into account. For such problems, it is often even difficult to construct a good feasible solution. We

  12. Modeling of capacitated transportation systems for integral scheduling

    NARCIS (Netherlands)

    Ebben, Mark; van der Heijden, Matthijs C.; Hurink, Johann L.; Schutten, Johannes M.J.

    Motivated by a planned automated cargo transportation network, we consider transportation problems in which the finite capacity of resources (such as vehicles, docks, parking places) has to be taken into account. For such problems, it is often even difficult to construct a good feasible solution. We

  13. Statistical model for suspension transport in porous media; Modelo estatistico para o transporte de suspensoes em meios porosos

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Adriano dos; Barros, Paulo [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2008-07-01

    An analytical model for transport of particulate suspensions in porous medium is discussed. The model takes microscopic rock characteristics into account and considers that size exclusion is the dominant particle retention mechanism. Analytical solutions for suspended and retained particle concentrations are obtained and the inverse problem is solved, allowing the filtration coefficients determination from experiments. The filtration coefficients for the proposed and the classical deep bed filtration models are calculated from experimental data available in the literature and the results are compared. Finally, it is shown that the proposed model tends to the classical deep bed filtration model when the particle retention probability tends to zero. (author)

  14. Modeling energy and charge transports in pi-conjugated systems

    Science.gov (United States)

    Shin, Yongwoo

    Carbon based pi-conjugated materials, such as conducting polymers, fullerene, carbon nanotubes, graphene, and conjugated dendrimers have attracted wide scientific attentions in the past three decades. This work presents the first unified model Hamiltonian that can accurately capture the low-energy excitations among all these pi-conjugated systems, even with the presence of defects and heterogeneous sites. Two transferable physical parameters are incorporated into the Su-Schrieffer-Heeger Hamiltonian to model conducting polymers beyond polyacetylene: the parameter gamma scales the electronphonon coupling strength in aromatic rings and the other parameter epsilon specifies the heterogeneous core charges. This generic Hamiltonian predicts the fundamental band gaps of polythiophene, polypyrrole, polyfuran, poly-(p-phenylene), poly-(p-phenylene vinylene), polyacenes, fullerene, carbon nanotubes, graphene, and graphene nanoribbons with an accuracy exceeding time-dependent density functional theory. Its computational costs for moderate-length polymer chains are more than eight orders of magnitude lower than first-principles approaches. The charge and energy transports along -conjugated backbones can be modeled on the adiabatic potential energy surface. The adiabatic minimum-energy path of a self-trapped topological soliton is computed for trans-polyacetylene. The frequently cited activation barrier via a ridge shift of the hyper-tangent order parameter overestimates its true value by 14 orders of magnitude. Self-trapped solitons migrate along the Goldstone mode direction with continuously adjusted amplitudes so that a small-width soliton expands and a large-width soliton shrinks when they move uphill. A soliton with the critical width may migrate without any amplitude modifications. In an open chain as solitons move from the chain center toward a chain edge, the minimum-energy path first follows a tilted washboard. Such a generic constrained Goldstone mode relaxation

  15. Modelling of the reactive transport of organic pollutants in ground water; Modellierung des reaktiven Transports organischer Schadstoffe im Grundwasser

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, W. [Heidelberg Univ. (Germany). Inst. fuer Umweltphysik

    1999-07-01

    The book describes reactive transport of organic pollutants in ground water and its quantitative monitoring by means of numerical reaction transport models. A brief introduction dealing with the importance of and hazards to ground water and opportunities for making use of ground water models is followed by a more detailed chapter on organic pollutants in ground water. Here the focus is on organochlorine compounds and mineral oil products. Described are propagation mechanisms for these substances in the ground and, especially, their degradability in ground water. A separate chapter is dedicated to possibilities for cleaning up polluted ground water aquifers. The most important decontamination techniques are presented, with special emphasis on in-situ processes with hydraulic components. Moreover, this chapter discusses the self-cleaning capability of aquifers and the benefits of the application of models to ground water cleanup. In the fourth chapter the individual components of reaction transport models are indicated. Here it is, inter alia, differences in the formulation of reaction models as to their complexity, and coupling between suspended matter transport and reaction processes that are dealt with. This chapter ends with a comprehensive survey of literature regarding the application of suspended matter transport models to real ground water accidents. Chapter 5 consists of a description of the capability and principle of function of the reaction transport model TBC (transport biochemism/chemism). This model is used in the two described applications to the reactive transport of organic pollutants in ground water. (orig.) [German] Inhalt des vorliegenden Buches ist die Darstellung des reaktiven Transports organischer Schadstoffe im Grundwasser und dessen quantitative Erfassung mithilfe numerischer Reaktions-Transportmodelle. Auf eine kurze Einleitung zur Bedeutung und Gefaehrdung von Grundwasser und zu den Einsatzmoeglichkeiten von Grundwassermodellen folgt ein

  16. Modeling of Coastal Effluent Transport: an Approach to Linking of Far-field and Near-field Models

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhaoqing; Khangaonkar, Tarang P.

    2008-09-01

    One of the challenges in effluent transport modeling in coastal tidal environments is the proper calculation of initial dilution in connection with the far-field transport model. In this study, an approach of external linkage of far-field and near-field effluent transport models is presented, and applied to simulate the effluent transport in the Port Angeles Harbor, Washington in the Strait of Juan de Fuca. A near-field plume model was used to calculate the effluent initial dilution and a three-dimensional (3-D) hydrodynamic model was developed to simulate the tidal circulation and far-field effluent transport in the Port Angeles Harbor. In the present study, the hydrodynamic model was driven by tides and surface winds. Observed water surface elevation and velocity data were used to calibrate the model over a period covering the neap-spring tidal cycle. The model was also validated with observed surface drogue trajectory data. The model successfully reproduced the tidal dynamics in the study area and good agreements between model results and observed data were obtained. This study demonstrated that the linkage between the near-field and far-field models in effluent transport modeling can be achieved through iteratively adjusting the model grid sizes such that the far-field modeled dilution ratio and effluent concentration in the effluent discharge model grid cell match the concentration calculated by the near-field plume model.

  17. A Scandinavian Public Transport Model? Reform Changes in Denmark, Sweden and Norway

    DEFF Research Database (Denmark)

    Hansson, Lisa; Lissandrello, Enza; Næss, Petter

    2017-01-01

    model of public transport. The findings are based on public documents, reform evaluations, and statistics. This is the first paper focusing on Scandinavian public transport systems and their governing models per se, taking into account the considerable reforms of the 2000s. The results provide......Scandinavian public transport, especially aspects of how the Scandinavian countries (i.e., Sweden, Denmark, and Norway) have created governing structures for a cohesive public transport system, is often cited positively in international research. Scandinavia is often treated as a homogeneous unit...... in public transport research, which sometimes refers to the “Scandinavian model of public transport”. It is not uncommon for conclusions regarding Scandinavian countries to be based on analyses of just one country. Is there actually such a thing as a Scandinavian model of public transport? All around Europe...

  18. A coupled upland-erosion and instream hydrodynamic-sediment transport model for evaluating sediment transport in forested watersheds

    Science.gov (United States)

    W. J. Conroy; R. H. Hotchkiss; W. J. Elliot

    2006-01-01

    This article describes a prototype modeling system for assessing forest management-related erosion at its source and predicting sediment transport from hillslopes to stream channels and through channel networks to a watershed outlet. We demonstrate that it is possible to develop a land management tool capable of accurately assessing the primary impacts of...

  19. The concept and the development plan of national transport model of Ukraine

    Directory of Open Access Journals (Sweden)

    Anatoly Redziuk

    2017-05-01

    Full Text Available For discussion it is given the proposals to the a draft concept of national transport model of Ukraine with brief description of the goal, objectives, functions, constraints, architecture, basic principles and a priority action plan for establishment of the national transport model of Ukraine and a respective data center as a basic infrastructure component to ensure creation and subsequent functioning of the national transport model, as well as to enable continuous informational support of the transport industry to enhance its efficiency.

  20. Modelling the observed vertical transport of {sup 7}Be in specific soils with advection dispersion model

    Energy Technology Data Exchange (ETDEWEB)

    Torres Astorga, Romina; Velasco, Hugo; Valladares, Diego L.; Lohaiza, Flavia; Ayub, Jimena Juri; Rizzotto, Marcos [Grupo de Estudios Ambientales. Instituto de Matematica Aplicada San Luis - Universidad Nacional de San Luis - CONICET, San Luis (Argentina)

    2014-07-01

    {sup 7}Be is a short-lived environmental radionuclide, produced in the upper atmosphere by spallation of nitrogen and oxygen by cosmic rays. After of the production by the nuclear reaction, {sup 7}Be diffuses through the atmosphere until it attaches to atmospheric aerosols. Subsequently, it is deposited on the earth surface mainly as wet fallout. The main physical processes which transport {sup 7}Be in soil are diffusion and advection by water. Migration parameters and measurements confirm that sorption is the main physical process, which confines {sup 7}Be concentration to soil surface. The literature data show that in soils, {sup 7}Be is concentrated near the surface (0-2 cm) as it is adsorbed onto clay minerals after its deposition on the soil surface and does not penetrate deeper into soils due to its short half-life. The maximum mass activity density of {sup 7}Be is found at the point of input of the radionuclide, i.e. at the surface of the soil column, showing a exponential distribution profile typical of a purely diffusive transport. Many studies applying the advection dispersion models have been reported in the literature in order to modelling the transport of {sup 137}Cs in soils. On them, the models are used to achieve information of the mechanisms that govern the transport, i. e. the model is used to explain the soil profile of radionuclide. The effective dispersion coefficient and the apparent advection velocity of radionuclide in soil are also obtained by fitting the analytical solution of the model equation to measured depth distributions of the radionuclide. In this work, the advective dispersive transport model with linear sorption is used to analyze the vertical migration process of {sup 7}Be in soils of undisturbed or reference sites. The deposition history is approximated by pulse-like input functions and time dependent analytical solution of equation model is obtained. The values of dispersion coefficient and apparent advection velocity obtained

  1. Pesticide transport to tile-drained fields in SWAT model – macropore flow and sediment

    DEFF Research Database (Denmark)

    Lu, Shenglan; Trolle, Dennis; Blicher-Mathiesen, Gitte

    2015-01-01

    as a fraction of effective rainfall and transported to the tile drains directly. Macropore sediment transport is calculated similarly to the MACRO model (Jarvis et al., 1999). Mobile pesticide transport is calculated with a decay function with the flow, whereas sorbed pesticides transport is associated......Preferential flow and colloidal facilitated transport via macopores connected to tile drains are the main pathways for pesticide transport from agricultural areas to surface waters in some area. We developed a macropore flow module and a sediment transport module for the Soil and Water Assessment...... Tool (SWAT) to simulate transport of both mobile (e.g. Bentazon) and strongly sorbed (e.g. Diuron) pesticides in tile drains. Macropore flow is initiated when soil water content exceeds a threshold and rainfall intensity exceeds infiltration capacity. The amount of macropore flow is calculated...

  2. Numerical modeling transport phenomena in proton exchange membrane fuel cells

    Science.gov (United States)

    Suh, DongMyung

    To study the coupled phenomena occurring in proton exchange membrane fuel cells, a two-phase, one-dimensional, non-isothermal model is developed in the chapter 1. The model includes water phase change, proton transport in the membrane and electro-osmotic effect. The thinnest, but most complex layer in the membrane electrode assembly, catalyst layer, is considered an interfacial boundary between the gas diffusion layer and the membrane. Mass and heat transfer and electro-chemical reaction through the catalyst layer are formulated into equations, which are applied to boundary conditions for the gas diffusion layer and the membrane. Detail accounts of the boundary equations and the numerical solving procedure used in this work are given. The polarization curve is calculated at different oxygen pressures and compared with the experimental results. When the operating condition is changed along the polarization curve, the change of physicochemical variables in the membrane electrode assembly is studied. In particular, the over-potential diagram presents the usage of the electrochemical energy at each layer of the membrane electrode assembly. Humidity in supplying gases is one of the most important factors to consider for improving the performance of PEMFE. Both high and low humidity conditions can result in a deteriorating cell performance. The effect of humidity on the cell performance is studied in the chapter 2. First, a numerical model based on computational fluid dynamics is developed. Second, the cell performances are simulated, when the relative humidity is changed from 0% to 100% in the anode and the cathode channel. The simulation results show how humidity in the reactant gases affects the water content distribution in the membrane, the over-potential at the catalyst layers and eventually the cell performance. In particular, the rapid enhancement in the cell performance caused by self-hydrating membrane is captured by the simulation. Fully humidifying either H2

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. Influence of calcite on uranium(VI) reactive transport in the groundwater-river mixing zone.

    Science.gov (United States)

    Ma, Rui; Liu, Chongxuan; Greskowiak, Janek; Prommer, Henning; Zachara, John; Zheng, Chunmiao

    2014-01-01

    Calcite is an important, relatively soluble mineral phase that can affect uranium reactive transport in subsurface sediments. This study was conducted to investigate the distribution of calcite and its influence on uranium adsorption and reactive transport in the groundwater-river mixing zone of the Hanford 300A site, Washington State. Simulations using a two-dimensional (2D) reactive transport model under field-relevant hydrological and hydrogeochemical conditions revealed the development of a calcite reaction front through the mixing zone as a result of dynamic groundwater-river interactions. The calcite concentration distribution, in turn, affected the concentrations of aqueous carbonate and calcium, and pH through dissolution, as river waters intruded and receded from the site at different velocities in response to stage changes. The composition variations in groundwater subsequently influenced uranium mobility and discharge rates into the river in a complex fashion. The results implied that calcite distribution and concentration are important variables that need to be quantified for accurate reactive transport predictions of uranium, especially in dynamic groundwater-river mixing zones. © 2013.

  5. UPTRANS: an incremental transport model with feedback for quick-response strategy evaluation

    CSIR Research Space (South Africa)

    Venter, C

    2009-07-01

    Full Text Available The paper describes the development of a prototype transport model to be used for high-level evaluation of a potentially large number of alternative land use-transport scenarios. It uses advanced logit modelling to capture travel behaviour change...

  6. Modeling the co-transport of viruses and colloids in unsaturated porous media

    NARCIS (Netherlands)

    Seetha, N.; Mohan Kumar, M. S.; Hassanizadeh, S. Majid

    2015-01-01

    A mathematical model is developed to simulate the co-transport of viruses and colloids in unsaturated porous media under steady-state flow conditions. The virus attachment to the mobile and immobile colloids is described using a linear reversible kinetic model. Colloid transport is assumed to be

  7. New methods For Modeling Transport Of Water And Solutes In Soils

    DEFF Research Database (Denmark)

    Møldrup, Per

    Recent models for water and solute transport in unsaturated soils have been mechanistically based but numerically very involved. This dissertation concerns the development of mechanistically-based but numerically simple models for calculating and analyzing transport of water and solutes in soil...

  8. Homology Modelling of the GABA Transporter and Analysis of Tiagabine Binding

    DEFF Research Database (Denmark)

    Skovstrup, S.; Taboureau, Olivier; Bräuner-Osborne, H.

    2010-01-01

    A homology model of the human GABA transporter (GAT-1) based on the recently reported crystal structures of the bacterial leucine transporter from Aquifex aeolicus (LeuT) was developed. The stability of the resulting model embedded in a membrane environment was analyzed by extensive molecular...

  9. Combined physical and chemical nonequilibrium transport model: Analytical solution, moments, and application to colloids

    Science.gov (United States)

    The transport of solutes and colloids in porous media is influenced by a variety of physical and chemical nonequilibrium processes. A combined physical–chemical nonequilibrium (PCNE) model was therefore used to describe general mass transport. The model partitions the pore space into “mobile” and “i...

  10. Air gap membrane distillation. 1. Modelling and mass transport properties for hollow fibre membranes

    NARCIS (Netherlands)

    Guijt, C.M.; Meindersma, G.W.; Reith, T.; de Haan, A.B.

    2005-01-01

    A predictive model for air gap membrane distillation in a counter current flow configuration using fibre membranes is presented. The water vapour transport across the membrane is described by the dusty-gas model that uses constant membrane mass transport parameters to describe simultaneous Knudsen

  11. Homology modeling of the serotonin transporter: Insights into the primary escitalopram-binding Site

    DEFF Research Database (Denmark)

    Jørgensen, Anne Marie; Tagmose, L.; Jørgensen, A.M.M.

    2007-01-01

    -ray structure of the closely related amino acid transporter, Aquifex aeolicus leucine transporter (LeuT), provides an opportunity to develop a three-dimensional model of the structure of SERT. We present herein a homology model of SERT using LeuT as the template and containing escitalopram as a bound ligand...

  12. Modeling of flow and reactive transport in IPARS

    KAUST Repository

    Wheeler, Mary Fanett

    2012-03-11

    In this work, we describe a number of efficient and locally conservative methods for subsurface flow and reactive transport that have been or are currently being implemented in the IPARS (Integrated Parallel and Accurate Reservoir Simulator). For flow problems, we consider discontinuous Galerkin (DG) methods and mortar mixed finite element methods. For transport problems, we employ discontinuous Galerkin methods and Godunov-mixed methods. For efficient treatment of reactive transport simulations, we present a number of state-of-the-art dynamic mesh adaptation strategies and implementations. Operator splitting approaches and iterative coupling techniques are also discussed. Finally, numerical examples are provided to illustrate the capability of IPARS to treat general biogeochemistry as well as the effectivity of mesh adaptations with DG for transport. © 2012 Bentham Science Publishers. All rights reserved.

  13. Quantitative modeling of failure propagation in intelligent transportation systems.

    Science.gov (United States)

    2014-08-01

    Unmanned vehicles are projected to reach consumer use within this decade - related legislation has already passed in California. The : most significant technical challenge associated with these vehicles is their integration in transportation environm...

  14. OPE3 : A model system for single-molecule transport

    NARCIS (Netherlands)

    Frisenda, R.

    2016-01-01

    In this dissertation, charge-transport through individual organic molecules is investigated. The single molecules are contacted with two-terminal mechanically controllable break junction gold electrodes and their electrical and mechanical behavior studied at room and low temperature.

  15. Cost estimate modeling of transportation management plans for highway projects.

    Science.gov (United States)

    2012-05-01

    Highway rehabilitation and reconstruction projects frequently cause road congestion and increase safety concerns while limiting access for road users. State Transportation Agencies (STAs) are challenged to find safer and more efficient ways to renew ...

  16. Transportation conformity particulate matter hot-spot air quality modeling.

    Science.gov (United States)

    2013-07-01

    In light of the new development in particulate matter (PM) hot-spot regulations and Illinois Department : of Transportation (IDOT)s National Environmental Policy Act (NEPA) documentation requirements, : this project is intended to (1) perform and ...

  17. Development of regional public transportation GIS architecture and data model.

    Science.gov (United States)

    2012-05-01

    The seven Florida Department of Transportation : (FDOT) districts are multicounty districts that : each interact with a number of county and : municipal agencies, including local transit : agencies. FDOT District 7 includes the Tampa-St. : Petersburg...

  18. Method of model reduction and multifidelity models for solute transport in random layered porous media

    Science.gov (United States)

    Xu, Zhijie; Tartakovsky, Alexandre M.

    2017-09-01

    This work presents a method of model reduction that leads to models with three solutions of increasing fidelity (multifidelity models) for solute transport in a bounded layered porous media with random permeability. The model generalizes the Taylor-Aris dispersion theory to stochastic transport in random layered porous media with a known velocity covariance function. In the reduced model, we represent (random) concentration in terms of its cross-sectional average and a variation function. We derive a one-dimensional stochastic advection-dispersion-type equation for the average concentration and a stochastic Poisson equation for the variation function, as well as expressions for the effective velocity and dispersion coefficient. In contrast to the linear scaling with the correlation length and the mean velocity from macrodispersion theory, our model predicts a nonlinear and a quadratic dependence of the effective dispersion on the correlation length and the mean velocity, respectively. We observe that velocity fluctuations enhance dispersion in a nonmonotonic fashion (a stochastic spike phenomenon): The dispersion initially increases with correlation length λ, reaches a maximum, and decreases to zero at infinity (correlation). Maximum enhancement in dispersion can be obtained at a correlation length about 0.25 the size of the porous media perpendicular to flow. This information can be useful for engineering such random layered porous media. Numerical simulations are implemented to compare solutions with varying fidelity.

  19. Modelling woody material transport and deposition in alpine rivers

    OpenAIRE

    B. Mazzorana; J. Hübl; Zischg, Andreas Paul; Largiader, A.

    2011-01-01

    Recent flood events in Switzerland and Western Austria in 2005 were characterised by an increase in impacts and associated losses due to the transport of woody material. As a consequence, protection measures and bridges suffered considerable damages. Furthermore, cross-sectional obstructions due to woody material entrapment caused unexpected flood plain inundations resulting in severe damage to elements at risk. Until now, the transport of woody material is neither sufficiently taken in...

  20. Signature project 1B-integrated land-use, transportation and environmental modeling.

    Science.gov (United States)

    2014-05-01

    Land use and transportation are inextricably linked. Models that capture the dynamics and interactions of both systems are indispensable for evaluating alternative courses of action in policy and investment. These models must be spatially disaggregat...

  1. Machine learning in updating predictive models of planning and scheduling transportation projects

    Science.gov (United States)

    1997-01-01

    A method combining machine learning and regression analysis to automatically and intelligently update predictive models used in the Kansas Department of Transportations (KDOTs) internal management system is presented. The predictive models used...

  2. Two-Dimensional Subsurface Flow, Fate and Transport of Microbes and Chemicals (2DFATMIC) Model

    Science.gov (United States)

    This model simulates subsurface flow, fate, and transport of contaminants that are undergoing chemical or biological transformations. This model is applicable to transient conditions in both saturated and unsaturated zones.

  3. Hydrogeochemical alteration of groundwater due to a CO2 injection test into a shallow aquifer in Northeast Germany

    Science.gov (United States)

    Dethlefsen, Frank; Peter, Anita; Hornbruch, Götz; Lamert, Hendrik; Garbe-Schönberg, Dieter; Beyer, Matthias; Dietrich, Peter; Dahmke, Andreas

    2014-05-01

    The accidental release of CO2 into potable aquifers, for instance as a consequence of a leakage out of a CO2 store site, can endanger drinking water resources due to the induced geochemical processes. A 10-day CO2 injection experiment into a shallow aquifer was carried out in Wittstock (Northeast Germany) in order to investigate the geochemical impact of a CO2 influx into such an aquifer and to test different monitoring methods. Information regarding the site investigation, the injection procedure monitoring setup, and first geochemical monitoring results are described in [1]. Apart from the utilization of the test results to evaluate monitoring approaches [2], further findings are presented on the evaluation of the geophysical monitoring [3], and the monitoring of stable carbon isotopes [4]. This part of the study focuses of the hydrogeochemical alteration of groundwater due to the CO2 injection test. As a consequence of the CO2 injection, major cations were released, i.e. concentrations increased, whereas major anion concentrations - beside bicarbonate - decreased, probably due to increased anion sorption capacity at variably charged exchange sites of minerals. Trace element concentrations increased as well significantly, whereas the relative concentration increase was far larger than the relative concentration increase of major cations. Furthermore, geochemical reactions show significant spatial heterogeneity, i.e. some elements such as Cr, Cu, Pb either increased in concentration or remained at stable concentrations with increasing TIC at different wells. Statistical analyses of regression coefficients confirm the different spatial reaction patterns at different wells. Concentration time series at single wells give evidence, that the trace element release is pH dependent, i.e. trace elements such as Zn, Ni, Co are released at pH of around 6.2-6.6, whereas other trace elements like As, Cd, Cu are released at pH of 5.6-6.4. [1] Peter, A., et al., Investigation of

  4. Mass balance inverse modelling of methane in the 1990s using a Chemistry Transport Model

    Science.gov (United States)

    Butler, T. M.; Simmonds, I.; Rayner, P. J.

    2004-12-01

    A mass balance inverse modelling procedure is applied with a time-dependent methane concentration boundary condition and a chemical transport model to relate observed changes in the surface distribution of methane mixing ratios during the 1990s to changes in its surface sources. The model reproduces essential features of the global methane cycle, such as the latitudinal distribution and seasonal cycle of fluxes, without using a priori knowledge of methane fluxes. A detailed description of the temporal and spatial variability of the fluxes diagnosed by the inverse procedure is presented, and compared with previously hypothesised changes in the methane budget, and previous inverse modelling studies. The sensitivity of the inverse results to the forcing data supplied by surface measurements of methane from the NOAA CMDL cooperative air sampling network is also examined. This work serves as an important starting point for future inverse modelling work examining changes in both the source and sink terms in the methane budget together.

  5. Mass balance inverse modelling of methane in the 1990s using a Chemistry Transport Model

    Directory of Open Access Journals (Sweden)

    T. M. Butler

    2004-01-01

    Full Text Available A mass balance inverse modelling procedure is applied with a time-dependent methane concentration boundary condition and a chemical transport model to relate observed changes in the surface distribution of methane mixing ratios during the 1990s to changes in its surface sources. The model reproduces essential features of the global methane cycle, such as the latitudinal distribution and seasonal cycle of fluxes, without using a priori knowledge of methane fluxes. A detailed description of the temporal and spatial variability of the fluxes diagnosed by the inverse procedure is presented, and compared with previously hypothesised changes in the methane budget, and previous inverse modelling studies. The sensitivity of the inverse results to the forcing data supplied by surface measurements of methane from the NOAA CMDL cooperative air sampling network is also examined. This work serves as an important starting point for future inverse modelling work examining changes in both the source and sink terms in the methane budget together.

  6. Risk Evaluation of Railway Coal Transportation Network Based on Multi Level Grey Evaluation Model

    Science.gov (United States)

    Niu, Wei; Wang, Xifu

    2018-01-01

    The railway transport mode is currently the most important way of coal transportation, and now China’s railway coal transportation network has become increasingly perfect, but there is still insufficient capacity, some lines close to saturation and other issues. In this paper, the theory and method of risk assessment, analytic hierarchy process and multi-level gray evaluation model are applied to the risk evaluation of coal railway transportation network in China. Based on the example analysis of Shanxi railway coal transportation network, to improve the internal structure and the competitiveness of the market.

  7. PARALLEL MEASUREMENT AND MODELING OF TRANSPORT IN THE DARHT II BEAMLINE ON ETA II

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, F W; Raymond, B A; Falabella, S; Lee, B S; Richardson, R A; Weir, J T; Davis, H A; Schultze, M E

    2005-05-31

    To successfully tune the DARHT II transport beamline requires the close coupling of a model of the beam transport and the measurement of the beam observables as the beam conditions and magnet settings are varied. For the ETA II experiment using the DARHT II beamline components this was achieved using the SUICIDE (Simple User Interface Connecting to an Integrated Data Environment) data analysis environment and the FITS (Fully Integrated Transport Simulation) model. The SUICIDE environment has direct access to the experimental beam transport data at acquisition and the FITS predictions of the transport for immediate comparison. The FITS model is coupled into the control system where it can read magnet current settings for real time modeling. We find this integrated coupling is essential for model verification and the successful development of a tuning aid for the efficient convergence on a useable tune. We show the real time comparisons of simulation and experiment and explore the successes and limitations of this close coupled approach.

  8. Modeling Polymer Stabilized Nano-scale Zero Valent Iron Transport Experiments in Porous Media to Understand the Transport Behavior

    Science.gov (United States)

    Mondal, P.; Krol, M.; Sleep, B. E.

    2015-12-01

    A wide variety of groundwater contaminants can be treated with nano-scale zero valent iron (nZVI). However, delivery of nZVI in the subsurface to the treatment zones is challenging as the bare nZVI particles have a higher tendency to agglomerate. The subsurface mobility of nZVI can be enhanced by stabilizing nZVI with polymer, such as carboxymethyl cellulose (CMC). In this study, numerical simulations were conducted to evaluate CMC stabilized nZVI transport behavior in porous media. The numerical simulations were based on a set of laboratory-scale transport experiments that were conducted in a two-dimensional water-saturated glass-walled sandbox (length - 55 cm; height - 45 cm; width - 1.4 cm), uniformly packed with silica sand. In the transport experiments: CMC stabilized nZVI and a non-reactive dye tracer Lissamine Green B (LGB) were used; water specific discharge and CMC concentration were varied; movements of LGB, and CMC-nZVI in the sandbox were tracked using a camera, a light source and a dark box. The concentrations of LGB, CMC, and CMC-nZVI at the sandbox outlet were analyzed. A 2D multiphase flow and transport model was applied to simulate experimental results. The images from LGB dye transport experiments were used to determine the pore water velocities and media permeabilities in various layers in the sand box. These permeability values were used in the subsequent simulations of CMC-nZVI transport. The 2D compositional simulator, modified to include colloid filtration theory (CFT), treated CMC as a solute and nZVI as a colloid. The simulator included composition dependent viscosity to account for CMC injection and mixing, and attachment efficiency as a fitting parameter for nZVI transport modeling. In the experiments, LGB and CMC recoveries were greater than 95%; however, CMC residence time was significantly higher than the LGB residence time and the higher CMC concentration caused higher pressure drops in the sandbox. The nZVI recovery was lower than 40

  9. Modeling sediment transport with an integrated view of the biofilm effects

    Science.gov (United States)

    Fang, H. W.; Lai, H. J.; Cheng, W.; Huang, L.; He, G. J.

    2017-09-01

    Most natural sediment is invariably covered by biofilms in reservoirs and lakes, which have significant influence on bed form dynamics and sediment transport, and also play a crucial role in natural river evolution, pollutant transport, and habitat changes. However, most models for sediment transport are based on experiments using clean sediments without biological materials. In this study, a three-dimensional mathematical model of hydrodynamics and sediment transport is presented with a comprehensive consideration of the biofilm effects. The changes of the bed resistance mainly due to the different bed form dynamics of the biofilm-coated sediment (biosediment), which affect the hydrodynamic characteristics, are considered. Moreover, the variations of parameters related to sediment transport after the biofilm growth are integrated, including the significant changes of the incipient velocity, settling velocity, reference concentration, and equilibrium bed load transport rate. The proposed model is applied to evaluate the effects of biofilms on the hydrodynamic characteristics and sediment transport in laboratory experiments. Results indicate that the mean velocity increases after the biofilm growth, and the turbulence intensity near the river bed decreases under the same flow condition. Meanwhile, biofilm inhibits sediment from moving independently. Thus, the moderate erosion is observed for biosediment resulting in smaller suspended sediment concentrations. The proposed model can reasonably reflect these sediment transport characteristics with biofilms, and the approach to integration of the biological impact could also be used in other modeling of sediment transport, which can be further applied to provide references for the integrated management of natural aqueous systems.

  10. The Impact of Early Time Behavior of Solute Transport at High Peclet Number on Upscaled Markovian Transport Models

    Science.gov (United States)

    Sund, N. L.; Bolster, D.; Benson, D. A.

    2015-12-01

    In order to predict transport of solutes, upscaling techniques are often applied. After the amount of time it takes the solute to sample all of the velocities in the system, the upscaling process is well understood and fairly simple to implement. But in highly heterogeneous velocity fields, this amount of time may be prohibitively long. When there is a need to predict transport at earlier times, the upscaling process is more difficult because the solute tends to stay on or near its initial streamline, inducing a correlation between its average velocity over fixed distances (or times), which must be accounted for. A Spatial Markov model was developed in 2008 that does just that[1]. It accounts for the velocity correlation by treating the transport process as a Markov Chain. This model has been successfully applied to predict solute transport in a large variety of complicated flow fields and is becoming increasing popular. It almost seems as though it works for every situation, but so far no rigorous study has gone into determining its limitations. So we have decided to take a step back and ask: when is this model valid? We understand the asymptotic behavior in the limit as t→ ∞, but what about in the limit as 1/t→ ∞ (or t→ 0)? Are the assumptions of the Spatial Markov model valid over all length (and time) scales? It turns out that the answer is no. At very early times, the transport process is diffusion dominated, leading to non-monotonic correlation between solute particles' average velocity over consecutive space and time steps. The assumptions of the Spatial Markov model only hold after this early diffusive regime ends and the correlation function peaks. We find the location of the peak in the correlation function for transport in simple stratified flows and show the effect of using the Spatial Markov model over length scales on either side of the peak.REFERENCES[1] T.L. Borgne, M. Dentz, J. Carrera: Spatial Markov processes for modeling Lagrangian

  11. Transporter-Enzyme Interplay: Deconvoluting Effects of Hepatic Transporters and Enzymes on Drug Disposition Using Static and Dynamic Mechanistic Models.

    Science.gov (United States)

    Varma, Manthena V; El-Kattan, Ayman F

    2016-07-01

    A large body of evidence suggests hepatic uptake transporters, organic anion-transporting polypeptides (OATPs), are of high clinical relevance in determining the pharmacokinetics of substrate drugs, based on which recent regulatory guidances to industry recommend appropriate assessment of investigational drugs for the potential drug interactions. We recently proposed an extended clearance classification system (ECCS) framework in which the systemic clearance of class 1B and 3B drugs is likely determined by hepatic uptake. The ECCS framework therefore predicts the possibility of drug-drug interactions (DDIs) involving OATPs and the effects of genetic variants of SLCO1B1 early in the discovery and facilitates decision making in the candidate selection and progression. Although OATP-mediated uptake is often the rate-determining process in the hepatic clearance of substrate drugs, metabolic and/or biliary components also contribute to the overall hepatic disposition and, more importantly, to liver exposure. Clinical evidence suggests that alteration in biliary efflux transport or metabolic enzymes associated with genetic polymorphism leads to change in the pharmacodynamic response of statins, for which the pharmacological target resides in the liver. Perpetrator drugs may show inhibitory and/or induction effects on transporters and enzymes simultaneously. It is therefore important to adopt models that frame these multiple processes in a mechanistic sense for quantitative DDI predictions and to deconvolute the effects of individual processes on the plasma and hepatic exposure. In vitro data-informed mechanistic static and physiologically based pharmacokinetic models are proven useful in rationalizing and predicting transporter-mediated DDIs and the complex DDIs involving transporter-enzyme interplay. © 2016, The American College of Clinical Pharmacology.

  12. Hydrogeochemical investigation of groundwater in shallow coastal aquifer of Khulna District, Bangladesh

    Science.gov (United States)

    Islam, S. M. Didar-Ul; Bhuiyan, Mohammad Amir Hossain; Rume, Tanjena; Azam, Gausul

    2017-12-01

    Groundwater acts as a lifeline in the coastal regions to meet out the domestic, drinking, irrigational and industrial needs. To investigate the hydrogeochemical characteristics of groundwater and its suitability, twenty samples were collected from the shallow tubewells of study area having screen depth 21-54 m. The water quality assessment has been carried out by evaluating the physicochemical parameters such as temperature, pH, EC, TDS and major ions i.e., Na+, K+, Ca2+, Mg2+, Cl-, SO4 2-, NO3 -, HCO3 -. Results found that, the water is slightly alkaline and brackish in nature. The trends of cations and anions are Na+ > Ca2+ > Mg2+ > K+ and Cl- > HCO3 - > SO4 2- > NO3 -, respectively and Na-Cl-HCO3 is the dominant groundwater type. The analyzed samples were also characterized with different indices, diagram and permissible limit i.e., electric conductivity (EC), total dissolved solids (TDS), chloride content (Cl), soluble sodium percentage (SSP), sodium adsorption ratio (SAR), residual sodium carbonate (RSC), magnesium adsorption ratio (MAR), Kelley's ratio (KR), Wilcox diagram and USSL diagram, and results showed that groundwater are not suitable for drinking and irrigational use. The factors responsible for the geochemical characterization were also attempted by using standard plot and it was found that mixing of seawater with entrapped water plays a significant role in the study area.

  13. Hydrogeochemical Characteristics of Groundwater Highly Polluted with Nitrate in an Agricultural Area of Hongseong, Korea

    Directory of Open Access Journals (Sweden)

    Hyun-su Kim

    2016-08-01

    Full Text Available The hydrogeochemical characteristics of groundwater, in an area where widespread contamination by nitrate ( NO 3 − was anticipated, were studied using traditional geochemical investigation and multivariate statistical analysis. Widespread NO 3 − contamination as high as 67.2 mg/L as NO3–N was observed, and positively correlated with that for chemicals ( Cl − , major cations with surface origin. Principal component analysis (PCA revealed that three processes affected groundwater chemistry of the area: (1 leaching of pollutants from the ground surface; (2 reduction of NO 3 − in areas with low dissolved oxygen (DO; and (3 ingress of low NO 3 − deep groundwater. Five sample groups were identified from cluster analysis, and analysis of land use patterns around each group showed that fate and distribution of NO 3 − contamination were mainly controlled by surface topography and predominant land use type. The highest NO 3 − concentrations were associated with confined livestock feeding operations in hilly terrain areas, where infiltrating water also had high DO. Lower NO 3 − concentrations found in the lowland flat areas were thought to be due to either reducing conditions in rice paddies leading to N attenuation or drawing in of deep groundwater by pumping to meet agricultural needs during periods of low rainfall.

  14. Uranium hydrogeochemical and stream sediment reconnaissance of the Survey Pass NTMS quadrangle, Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Shettel, D.L. Jr.; Langfeldt, S.L.; Youngquist, C.A.; D' Andrea, R.F. Jr.; Zinkl, R.J. (comps.)

    1981-09-01

    This report presents results of a Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) of the Survey Pass NTMS quadrangle, Alaska. In addition to this abbreviated data release, more complete data are available to the public in machine-readable form through the Grand Junction Office Information System at Oak Ridge National Laboratory. Presented in this data release are location data, field analyses, and laboratory analyses of several different sample media. For the sake of brevity, many field site observations have not been included in this volume. These data are, however, available on the magnetic tape. Appendix A describes the sample media and summarizes the analytical results for each medium. The data were subdivided by one of the Los Alamos National Laboratory (LANL) sorting programs of Zinkl and others (1981a) into stream sediment samples. For the group which contains a sufficient number of observations, statistical tables, tables of raw data, and 1:1000000 scale maps of pertinent elements have been included in this report. In addition, maps showing results of multivariate statistical analyses have been included. Further information about the HSSR program in general, or about the LANL portion of the program in particular, can be obtained in quarterly or semiannual program progress reports on open-file at DOE's Technical Library in Grand Junction. Information about the field and analytical procedures used by LANL during sample collection and analysis may be found in any HSSR data release prepared by the LANL and will not be included in this report.

  15. Hydrogeochemical processes in the Plio-Quaternary Remila aquifer (Khenchela, Algeria)

    Science.gov (United States)

    Aouidane, Laiche; Belhamra, Mohamed

    2017-06-01

    The Remila Plain is a synclinal structure in northeast Algeria, situated within a semi-arid climate zone and composed of Mio-Pliocene-Quaternary deposits. Within the syncline, the Plio-Quaternary aquifer is the main source of drinking water for cattle and for agricultural irrigation water. This work aims to investigate the origin of groundwater mineralization and to identify the primary hydrogeochemical processes controlling groundwater evolution in the Remila aquifer. A total of 86 water samples from boreholes were analyzed for major, minor and stable isotopes (18O, 2H) over three seasons: first during low water levels in 2013, second during high water levels in 2014 and third for stable isotopes during low water levels in 2015. The analysis showed that the aquifer is controlled by five principal geochemical processes: (I) the dissolution of evaporite rocks, (II) cation exchange and reverse exchange reactions, (III) congruent dissolution of carbonates (calcite, dolomite) coupled with the dissolution of gypsum and calcite precipitation, (IV) sulfate reduction under anaerobic conditions, and (V) saltwater intrusion in the northeastern Sabkha plains. The 18O and deuterium concentrations in groundwater are very low, indicating that the aquifer is recharged by evaporated rainfall originating from the north slope of the Aurès Mountains which confirms that the aquifer is recharged in the southern part of the plain.

  16. Hydrogeochemical investigations in a drained lake area: the case of Xynias basin (Central Greece).

    Science.gov (United States)

    Charizopoulos, Nikos; Zagana, Eleni; Stamatis, Georgios

    2016-08-01

    In Xynias drained Lake Basin's area, central Greece, a hydrogeochemical research took place including groundwater sampling from 30 sampling sites, chemical analysis, and statistical analysis. Groundwaters present Ca-Mg-HCO3 as the dominant hydrochemical type, while their majority is mixed waters with non-dominant ion. They are classified as moderately hard to hard and are characterized by oxidizing conditions. They are undersaturated with respect to gypsum, anhydrite, fluorite, siderite, and magnesite and oversaturated in respect to calcite, aragonite, and dolomite. Nitrate concentration ranges from 4.4 to 107.4 mg/L, meanwhile 13.3 % of the samples exceed the European Community (E.C.) drinking water permissible limit. The trace elements Fe, Ni, Cr, and Cd present values of 30, 80, 57, and 50 %, respectively, above the maximum permissible limit set by E.C. Accordingly, the majority of the groundwaters are considered unsuitable for drinking water needs. Sodium adsorption ratio values (0.04-3.98) and the electrical conductivity (227-1200 μS/cm) classify groundwaters as suitable for irrigation uses, presenting low risk and medium soil alkalization risk. Factor analysis shows that geogenic processes associated with the former lacustrine environment and anthropogenic influences with the use of fertilizers are the major factors that characterized the chemical composition of the groundwaters.

  17. Comparative study of boron transport models in NRC Thermal-Hydraulic Code Trace

    Energy Technology Data Exchange (ETDEWEB)

    Olmo-Juan, Nicolás; Barrachina, Teresa; Miró, Rafael; Verdú, Gumersindo; Pereira, Claubia, E-mail: nioljua@iqn.upv.es, E-mail: tbarrachina@iqn.upv.es, E-mail: rmiro@iqn.upv.es, E-mail: gverdu@iqn.upv.es, E-mail: claubia@nuclear.ufmg.br [Institute for Industrial, Radiophysical and Environmental Safety (ISIRYM). Universitat Politècnica de València (Spain); Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear

    2017-07-01

    Recently, the interest in the study of various types of transients involving changes in the boron concentration inside the reactor, has led to an increase in the interest of developing and studying new models and tools that allow a correct study of boron transport. Therefore, a significant variety of different boron transport models and spatial difference schemes are available in the thermal-hydraulic codes, as TRACE. According to this interest, in this work it will be compared the results obtained using the different boron transport models implemented in the NRC thermal-hydraulic code TRACE. To do this, a set of models have been created using the different options and configurations that could have influence in boron transport. These models allow to reproduce a simple event of filling or emptying the boron concentration in a long pipe. Moreover, with the aim to compare the differences obtained when one-dimensional or three-dimensional components are chosen, it has modeled many different cases using only pipe components or a mix of pipe and vessel components. In addition, the influence of the void fraction in the boron transport has been studied and compared under close conditions to BWR commercial model. A final collection of the different cases and boron transport models are compared between them and those corresponding to the analytical solution provided by the Burgers equation. From this comparison, important conclusions are drawn that will be the basis of modeling the boron transport in TRACE adequately. (author)

  18. Hydrogeologic Framework Model for the Saturated Zone Site Scale flow and Transport Model

    Energy Technology Data Exchange (ETDEWEB)

    T. Miller

    2004-11-15

    The purpose of this report is to document the 19-unit, hydrogeologic framework model (19-layer version, output of this report) (HFM-19) with regard to input data, modeling methods, assumptions, uncertainties, limitations, and validation of the model results in accordance with AP-SIII.10Q, Models. The HFM-19 is developed as a conceptual model of the geometric extent of the hydrogeologic units at Yucca Mountain and is intended specifically for use in the development of the ''Saturated Zone Site-Scale Flow Model'' (BSC 2004 [DIRS 170037]). Primary inputs to this model report include the GFM 3.1 (DTN: MO9901MWDGFM31.000 [DIRS 103769]), borehole lithologic logs, geologic maps, geologic cross sections, water level data, topographic information, and geophysical data as discussed in Section 4.1. Figure 1-1 shows the information flow among all of the saturated zone (SZ) reports and the relationship of this conceptual model in that flow. The HFM-19 is a three-dimensional (3-D) representation of the hydrogeologic units surrounding the location of the Yucca Mountain geologic repository for spent nuclear fuel and high-l