WorldWideScience

Sample records for solute transport experiments

  1. Stochastic analysis of transport of conservative solutes in caisson experiments

    International Nuclear Information System (INIS)

    Dagan, G.

    1995-01-01

    The Los Alamos National Laboratory has conducted in the past a series of experiments of transport of conservative and reactive solutes. The experimental setup and the experimental results are presented in a series of reports. The main aim of the experiments was to validate models of transport of solutes in unsaturated flow at the caisson intermediate scale, which is much larger than the one pertaining to laboratory columns. First attempts to analyze the experimental results were by one-dimensional convective-dispersion models. These models could not explain the observed solute breakthrough curves and particularly the large solute dispersion in the caisson effluent Since there were some question marks about the uniformity of water distribution at the caisson top, the transport experiments were repeated under conditions of saturated flow. In these experiments constant heads were applied at the top and the bottom of the caisson and the number of concentration monitoring stations was quadrupled. The analysis of the measurements by the same one-dimensional model indicated clearly that the fitted dispersivity is much larger than the pore-sole dispersivity and that it grows with the distance in an approximately linear fashion. This led to the conclusion, raised before, that transport in the caisson is dominated by heterogeneity effects, i.e. by spatial variability of the material Such effects cannot be captured by traditional one-dimensional models. In order to account for the effect of heterogeneity, the saturated flow experiments have been analyzed by using stochastic transport modeling. The apparent linear growth of dispersivity with distance suggested that the system behaves like a stratified one. Consequently, the model of Dagan and Bresier has been adopted in order to interpret concentration measurements. In this simple model the caisson is viewed as a bundle of columns of different permeabilities, which are characterized by a p.d.f. (probability denasity function)

  2. UrbanTransport Solution An Experience From Prague

    African Journals Online (AJOL)

    unique firstlady

    Based on the result of the research ... associated with road transport like its impact on environment ..... Prague is utilizing a variety of marketing strategies used for many years in ... at strategic metro stations providing customers with maps , time ...

  3. UrbanTransport Solution An Experience From Prague | Jeremiah ...

    African Journals Online (AJOL)

    This paper examines the urban transport problems in Prague in Czech Republic. Based on the result of the research conducted, it was found that with the collapsed of Communism in Czech Republic, there was an upsurge in the use of private cars which was not possible during communism because the law does not ...

  4. Used Fuel Logistics: Decades of Experience with transportation and Interim storage solutions

    Energy Technology Data Exchange (ETDEWEB)

    Orban, G.; Shelton, C.

    2015-07-01

    Used fuel inventories are growing worldwide. While some countries have opted for a closed cycle with recycling, numerous countries must expand their interim storage solutions as implementation of permanent repositories is taking more time than foreseen. In both cases transportation capabilities will have to be developed. AREVA TN has an unparalleled expertise with transportation of used fuel. For more than 50 years AREVA TN has safely shipped more than 7,000 used fuel transport casks. The transportation model that was initially developed in the 1970s has been adapted and enhanced over the years to meet more restrictive regulatory requirements and evolving customer needs, and to address public concerns. The numerous “lessons learned” have offered data and guidance that have allowed for also efficient and consistent improvement over the decades. AREVA TN has also an extensive experience with interim dry storage solutions in many countries on-site but also is working with partners to developed consolidated interim storage facility. Both expertise with storage and transportation contribute to safe, secure and smooth continuity of the operations. This paper will describe decades of experience with a very successful transportation program as well as interim storage solutions. (Author)

  5. Laboratory experiments on solute transport in bimodal porous media under cyclic precipitation-evaporation boundary conditions

    Science.gov (United States)

    Cremer, Clemens; Neuweiler, Insa

    2016-04-01

    Flow and solute transport in the shallow subsurface is strongly governed by atmospheric boundary conditions. Erratically varying infiltration and evaporation cycles lead to alternating upward and downward flow, as well as spatially and temporally varying water contents and associated hydraulic conductivity of the prevailing materials. Thus presenting a highly complicated, dynamic system. Knowledge of subsurface solute transport processes is vital to assess e.g. the entry of, potentially hazardous, solutes to the groundwater and nutrient uptake by plant roots and can be gained in many ways. Besides field measurements and numerical simulations, physical laboratory experiments represent a way to establish process understanding and furthermore validate numerical schemes. With the aim to gain a better understanding and to quantify solute transport in the unsaturated shallow subsurface under natural precipitation conditions in heterogeneous media, we conduct physical laboratory experiments in a 22 cm x 8 cm x 1 cm flow cell that is filled with two types of sand and apply cyclic infiltration-evaporation phases at the soil surface. Pressure at the bottom of the domain is kept constant. Following recent studies (Lehmann and Or, 2009; Bechtold et al., 2011a), heterogeneity is introduced by a sharp vertical interface between coarse and fine sand. Fluorescent tracers are used to i) qualitatively visualize transport paths within the domain and ii) quantify solute leaching at the bottom of the domain. Temporal and spatial variations in water content during the experiment are derived from x-ray radiographic images. Monitored water contents between infiltration and evaporation considerably changed in the coarse sand while the fine sand remained saturated throughout the experiments. Lateral solute transport through the interface in both directions at different depths of the investigated soil columns were observed. This depended on the flow rate applied at the soil surface and

  6. Application of multiphysics models to efficient design of experiments of solute transport across articular cartilage.

    Science.gov (United States)

    Pouran, Behdad; Arbabi, Vahid; Weinans, Harrie; Zadpoor, Amir A

    2016-11-01

    Transport of solutes helps to regulate normal physiology and proper function of cartilage in diarthrodial joints. Multiple studies have shown the effects of characteristic parameters such as concentration of proteoglycans and collagens and the orientation of collagen fibrils on the diffusion process. However, not much quantitative information and accurate models are available to help understand how the characteristics of the fluid surrounding articular cartilage influence the diffusion process. In this study, we used a combination of micro-computed tomography experiments and biphasic-solute finite element models to study the effects of three parameters of the overlying bath on the diffusion of neutral solutes across cartilage zones. Those parameters include bath size, degree of stirring of the bath, and the size and concentration of the stagnant layer that forms at the interface of cartilage and bath. Parametric studies determined the minimum of the finite bath size for which the diffusion behavior reduces to that of an infinite bath. Stirring of the bath proved to remarkably influence neutral solute transport across cartilage zones. The well-stirred condition was achieved only when the ratio of the diffusivity of bath to that of cartilage was greater than ≈1000. While the thickness of the stagnant layer at the cartilage-bath interface did not significantly influence the diffusion behavior, increase in its concentration substantially elevated solute concentration in cartilage. Sufficient stirring attenuated the effects of the stagnant layer. Our findings could be used for efficient design of experimental protocols aimed at understanding the transport of molecules across articular cartilage. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    1987-06-01

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

  8. Coupling Solute and Fine Particle Transport with Sand Bed Morphodynamics within a Field Experiment

    Science.gov (United States)

    Phillips, C. B.; Ortiz, C. P.; Schumer, R.; Jerolmack, D. J.; Packman, A. I.

    2017-12-01

    Fine suspended particles are typically considered to pass through streams and rivers as wash load without interacting with the bed, however experiments have demonstrated that hyporheic flow causes advective exchange of fine particles with the stream bed, yielding accumulation of fine particle deposits within the bed. Ultimately, understanding river morphodynamics and ecosystem dynamics requires coupling both fine particle and solute transport with bed morphodynamics. To better understand the coupling between these processes we analyze a novel dataset from a controlled field experiment conducted on Clear Run, a 2nd order sand bed stream located within the North Carolina coastal plain. Data include concentrations of continuously injected conservative solutes and fine particulate tracers measured at various depths within the stream bed, overhead time lapse images of bed forms, stream discharge, and geomorphological surveys of the stream. We use image analysis of bed morphodynamics to assess exchange, retention, and remobilization of solutes and fine particles during constant discharge and a short duration experimental flood. From the images, we extract a time series of bedform elevations and scour depths for the duration of the experiment. The high-resolution timeseries of bed elevation enables us to assess coupling of bed morphodynamics with both the solute and fine particle flux during steady state mobile bedforms prior to the flood and to changing bedforms during the flood. These data allow the application of a stochastic modeling framework relating bed elevation fluctuations to fine particle residence times. This combined experimental and modeling approach ultimately informs our ability to predict not only the fate of fine particulate matter but also associated nutrient and carbon dynamics within streams and rivers.

  9. Solute transport and extraction by a single root in unsaturated soils: model development and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jaisoo; Sung, Kijune; Corapcioglu, M. Yavuz; Drew, Malcolm C

    2004-09-01

    A contaminant transport model was developed to simulate the fate and transport of organic compounds such as TNT (2,4,6-trinitrotoluene), using the single-root system. Onions were planted for this system with 50-ml plastic tubes. Mass in the soil, soil solution, root and leaf was monitored using {sup 14}C-TNT. Model parameters were acquired from the experiments in the single-root system and were used to simulate total TNT concentration in soil, providing the average concentrations in the rhizosphere and bulk soil as well as root and leaf compartments. Because the existing RCF (root concentration factor) and TSCF (transpiration stream concentration factor) equations based on log K{sub ow} (octanol-water partition coefficient) were not correlated to TNT uptake, a new term, root uptake rate (R{sub ur}), and a new T{sub scf} equation, based on the experimental data, were introduced in the proposed model. The results from both modeling and experimental studies showed higher concentrations of TNT in the rhizosphere than in the bulk soil, because mass transported from the surrounding soil into the rhizosphere was higher than that by root uptake.

  10. Pore-scale and Continuum Simulations of Solute Transport Micromodel Benchmark Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Oostrom, Martinus; Mehmani, Yashar; Romero Gomez, Pedro DJ; Tang, Y.; Liu, H.; Yoon, Hongkyu; Kang, Qinjun; Joekar Niasar, Vahid; Balhoff, Matthew; Dewers, T.; Tartakovsky, Guzel D.; Leist, Emily AE; Hess, Nancy J.; Perkins, William A.; Rakowski, Cynthia L.; Richmond, Marshall C.; Serkowski, John A.; Werth, Charles J.; Valocchi, Albert J.; Wietsma, Thomas W.; Zhang, Changyong

    2016-08-01

    Four sets of micromodel nonreactive solute transport experiments were conducted with flow velocity, grain diameter, pore-aspect ratio, and flow focusing heterogeneity as the variables. The data sets were offered to pore-scale modeling groups to test their simulators. Each set consisted of two learning experiments, for which all results was made available, and a challenge experiment, for which only the experimental description and base input parameters were provided. The experimental results showed a nonlinear dependence of the dispersion coefficient on the Peclet number, a negligible effect of the pore-aspect ratio on transverse mixing, and considerably enhanced mixing due to flow focusing. Five pore-scale models and one continuum-scale model were used to simulate the experiments. Of the pore-scale models, two used a pore-network (PN) method, two others are based on a lattice-Boltzmann (LB) approach, and one employed a computational fluid dynamics (CFD) technique. The learning experiments were used by the PN models to modify the standard perfect mixing approach in pore bodies into approaches to simulate the observed incomplete mixing. The LB and CFD models used these experiments to appropriately discretize the grid representations. The continuum model use published non-linear relations between transverse dispersion coefficients and Peclet numbers to compute the required dispersivity input values. Comparisons between experimental and numerical results for the four challenge experiments show that all pore-scale models were all able to satisfactorily simulate the experiments. The continuum model underestimated the required dispersivity values and, resulting in less dispersion. The PN models were able to complete the simulations in a few minutes, whereas the direct models needed up to several days on supercomputers to resolve the more complex problems.

  11. The use of laboratory experiments for the study of conservative solute transport in heterogeneous porous media

    Science.gov (United States)

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

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

  12. Cyclic deformation-induced solute transport in tissue scaffolds with computer designed, interconnected, pore networks: experiments and simulations.

    Science.gov (United States)

    Den Buijs, Jorn Op; Dragomir-Daescu, Dan; Ritman, Erik L

    2009-08-01

    Nutrient supply and waste removal in porous tissue engineering scaffolds decrease from the periphery to the center, leading to limited depth of ingrowth of new tissue into the scaffold. However, as many tissues experience cyclic physiological strains, this may provide a mechanism to enhance solute transport in vivo before vascularization of the scaffold. The hypothesis of this study was that pore cross-sectional geometry and interconnectivity are of major importance for the effectiveness of cyclic deformation-induced solute transport. Transparent elastic polyurethane scaffolds, with computer-programmed design of pore networks in the form of interconnected channels, were fabricated using a 3D printing and injection molding technique. The scaffold pores were loaded with a colored tracer for optical contrast, cyclically compressed with deformations of 10 and 15% of the original undeformed height at 1.0 Hz. Digital imaging was used to quantify the spatial distribution of the tracer concentration within the pores. Numerical simulations of a fluid-structure interaction model of deformation-induced solute transport were compared to the experimental data. The results of experiments and modeling agreed well and showed that pore interconnectivity heavily influences deformation-induced solute transport. Pore cross-sectional geometry appears to be of less relative importance in interconnected pore networks. Validated computer models of solute transport can be used to design optimal scaffold pore geometries that will enhance the convective transport of nutrients inside the scaffold and the removal of waste, thus improving the cell survivability deep inside the scaffold.

  13. Solute transport in soil

    NARCIS (Netherlands)

    Zee, van der S.E.A.T.M.; Leijnse, A.

    2013-01-01

    Solute transport is of importance in view of the movement of nutrient elements, e.g. towards the plant root system, and because of a broad range of pollutants. Pollution is not necessarily man induced, but may be due to geological or geohydrological causes, e.g. in the cases of pollution with

  14. Solute carrier transporters: Pharmacogenomics research ...

    African Journals Online (AJOL)

    Aghogho

    2010-12-27

    Dec 27, 2010 ... This paper reviews the solute carrier transporters and highlights the fact that there is much to be learnt from .... transporters, drug targets, effect or proteins and meta- ... basolateral or apical plasma membrane of polarized cells,.

  15. An energy-optimal solution for transportation control of cranes with double pendulum dynamics: Design and experiments

    Science.gov (United States)

    Sun, Ning; Wu, Yiming; Chen, He; Fang, Yongchun

    2018-03-01

    Underactuated cranes play an important role in modern industry. Specifically, in most situations of practical applications, crane systems exhibit significant double pendulum characteristics, which makes the control problem quite challenging. Moreover, most existing planners/controllers obtained with standard methods/techniques for double pendulum cranes cannot minimize the energy consumption when fulfilling the transportation tasks. Therefore, from a practical perspective, this paper proposes an energy-optimal solution for transportation control of double pendulum cranes. By applying the presented approach, the transportation objective, including fast trolley positioning and swing elimination, is achieved with minimized energy consumption, and the residual oscillations are suppressed effectively with all the state constrains being satisfied during the entire transportation process. As far as we know, this is the first energy-optimal solution for transportation control of underactuated double pendulum cranes with various state and control constraints. Hardware experimental results are included to verify the effectiveness of the proposed approach, whose superior performance is reflected by being experimentally compared with some comparative controllers.

  16. Model Simulations of a Field Experiment on Cation Exchange-affected Multicomponent Solute Transport in a Sandy Aquifer

    DEFF Research Database (Denmark)

    Bjerg, Poul Løgstrup; Ammentorp, Hans Christian; Christensen, Thomas Højlund

    1993-01-01

    A large-scale and long-term field experiment on cation exchange in a sandy aquifer has been modelled by a three-dimensional geochemical transport model. The geochemical model includes cation-exchange processes using a Gaines-Thomas expression, the closed carbonate system and the effects of ionic...... by batch experiments and by the composition of the cations on the exchange complex. Potassium showed a non-ideal exchange behaviour with K&z.sbnd;Ca selectivity coefficients indicating dependency on equivalent fraction and K+ concentration in the aqueous phase. The model simulations over a distance of 35 m...... and a period of 250 days described accurately the observed attenuation of Na and the expelled amounts of Ca and Mg. Also, model predictions of plateau zones, formed by interaction with the background groundwater, in general agreed satisfactorily with the observations. Transport of K was simulated over a period...

  17. Transport and reaction kinetics at the glass:solution interface region: results of repository-oriented leaching experiments

    International Nuclear Information System (INIS)

    Abrajano, T.A. Jr.; Bates, J.K.

    1987-01-01

    Repository-oriented leaching experiments involving Savannah River Laboratory (SRL) 165 type glass under a γ-radiation field (1 +/- 0.2 x 10 4 R/h) have been performed by the Nevada Nuclear Waste Storage Investigations (NNWSI) project. In this communication, they discuss glass surface analyses obtained by SEM, nuclear resonance profiling, and SIMS together with leachate solution data in relation to a mechanism that couples diffusion, hydrolysis (etching and gelation), and precipitation to qualitatively describe the release of different glass components to the leachant solutions. The release of mobile (e.g., Li) and partly mobile (e.g., B) species is controlled primarily by interdiffusion with water species across the interdiffusion zone. Glass components that are immobile in the interdiffusion zone are released to the solution by etching. For prediction of long-term steady-state concentrations of glass components with low solubility, the relative rates of release from the glass and secondary mineral precipitation must be taken into account. 20 references, 5 figures, 1 table

  18. Comparison of different soil water extraction systems for the prognoses of solute transport at the field scale using numerical simulations, field and lysimeter experiments

    Energy Technology Data Exchange (ETDEWEB)

    Weihermueller, L

    2005-07-01

    To date, the understanding of processes, factors, and interactions that influence the amount of extracted water and the solute composition sampled with suction cups is limited. But this information is required for process description of solute transport in natural soils. Improved system understanding can lead to a low cost and easy to install water sampling system which can help to predict solute transport in natural soils for the benefit of environmental protection. The main objectives of this work were to perform numerical simulations with different boundary conditions and to implement the findings in the interpretation of the lysimeter and field experiments. In a first part of this thesis, theoretical considerations on the processes affecting the spatial influence of a suction cup in soil and changes in solute transport initiated by the suction cups are presented, including testing and validation of available model and experimental approaches. In the second part, a detailed experimental study was conducted to obtain data for the comparison of the different soil water sampling systems. Finally, the numerical experiments of the suction cup influence were used for the interpretation of the experimental data. The main goals are summarized as follows: - Characterization of the suction cup activity domain (SCAD), suction cup extraction domain (SCED) and suction cup sampling area (SCSA) of active suction cups (definitions are given in Chapter 6). - Determination of the boundary conditions and soil properties [e.g. infiltration, applied suction, duration of water extraction, soil hydraulic properties and soil heterogeneity] affecting the activity domain, extraction domain and sampling area of a suction cup. - Identification of processes that change the travel time and travel time variance of solutes extracted by suction cups. - Validation of the numerically derived data with analytical and experimental data from literature. - Comparison of the experimental data obtained

  19. Peritoneal solute transport and inflammation.

    Science.gov (United States)

    Davies, Simon J

    2014-12-01

    The speed with which small solutes cross the peritoneal membrane, termed peritoneal solute transport rate (PSTR), is a key measure of individual membrane performance. PSTR can be quantified easily by using the 4-hour dialysate to plasma creatinine ratio, which, although only an approximation to the diffusive characteristics of the membrane, has been well validated clinically in terms of its relationship to patient survival and changes in longitudinal membrane function. This has led to changes in peritoneal dialysis modality use and dialysis prescription. An important determinant of PSTR is intraperitoneal inflammation, as exemplified by local interleukin 6 production, which is largely independent of systemic inflammation and its relationship to comorbid conditions and increased mortality. There is no strong evidence to support the contention that the peritoneal membrane in some individuals with high PSTR is qualitatively different at the start of treatment; rather, it represents a spectrum that is determined in part by genetic factors. Both clinical and experimental evidence support the view that persistent intraperitoneal inflammation, detected as a continuously high or increasing PSTR, may predispose the membrane to progressive fibrosis. Copyright © 2014 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

  20. Data on the solute concentration within the subsurface flows of Little Lost Man Creek in response to a transport experiment, Redwood National Park, northwest California

    Science.gov (United States)

    Zellweger, Gary W.; Kennedy, V.C.; Bencala, K.E.; Avanzino, R.J.; Jackman, A.P.; Triska, F.J.

    1986-01-01

    A solute transport experiment was conducted on a 327-m reach of Little Lost Man Creek, a small stream in Humboldt County, California. Solutes were injected for 20 days. Chloride was used as a conservative tracer; lithium, potassium, and strontium were used as reactive tracers. In addition, nitrate and phosphate were added as biological reactants. Eighteen shallow wells were dug along the length of the study reach, 1-10 m laterally from the edge of the stream. The wells and sites in the stream were monitored for the injected solutes during and after the injection. Solute concentrations in the wells and stream are indicative of transport properties of stream and subsurface channel flow. This report presents the results of the analyses of the well samples and chemical data relevant to the interpretation of hydrological and chemical interaction between the stream and adjacent channel subsurface flows in the streambed. Calculations of the percentage of streamwater in the wellwater were made from conservative tracer measurements. The composition of wellwater ranged from 47% to 100% streamwater with most values above 90%. The time for water to travel from the beginning of the study reach to the wells was approximately three times as great as the travel time in the stream at the same distance down the reach. The three conclusions that can be drawn are (1) water in the stream exchanges extensively with water in the rest of the channel; (2) the interstitial water in the channel gravels achieves almost the same composition as the stream; and (3) under low flow conditions the stream gravels contain a significant portion of the stream volume. Plots of normalized chloride, lithium, and strontium concentrations at three stream sites are included. (Author 's abstract)

  1. Neutralized transport experiment

    International Nuclear Information System (INIS)

    Roy, P.K.; Yu, S.S.; Eylon, S.; Henestroza, E.; Anders, A.; Gilson, E.P.; Bieniosek, F.M.; Greenway, W.G.; Logan, B.G.; Waldron, W.L.; Shuman, D.B.; Vanecek, D.L.; Welch, D.R.; Rose, D.V.; Thoma, C.; Davidson, R.C.; Efthimion, P.C.; Kaganovich, I.; Sefkow, A.B.; Sharp, W.M.

    2005-01-01

    Experimental details on providing active neutralization of high brightness ion beam have been demonstrated for Heavy Ion Fusion program. A K + beam was extracted from a variable-perveance injector and transported through 2.4 m long quadrupole lattice for final focusing. Neutralization was provided by a localized cathode arc plasma plug and a RF volume plasma system. Effects of beam perveance, emittance, convergence focusing angle, and axial focusing position on neutralization have been investigated. Good agreement has been observed with theory and experiment throughout the study

  2. Reactive solute transport in acidic streams

    Science.gov (United States)

    Broshears, R.E.

    1996-01-01

    Spatial and temporal profiles of Ph and concentrations of toxic metals in streams affected by acid mine drainage are the result of the interplay of physical and biogeochemical processes. This paper describes a reactive solute transport model that provides a physically and thermodynamically quantitative interpretation of these profiles. The model combines a transport module that includes advection-dispersion and transient storage with a geochemical speciation module based on MINTEQA2. Input to the model includes stream hydrologic properties derived from tracer-dilution experiments, headwater and lateral inflow concentrations analyzed in field samples, and a thermodynamic database. Simulations reproduced the general features of steady-state patterns of observed pH and concentrations of aluminum and sulfate in St. Kevin Gulch, an acid mine drainage stream near Leadville, Colorado. These patterns were altered temporarily by injection of sodium carbonate into the stream. A transient simulation reproduced the observed effects of the base injection.

  3. Urban Transportation: Issue and Solution

    Directory of Open Access Journals (Sweden)

    Haryati Shafii

    2011-10-01

    Full Text Available Generally, quality of life of urban population is heavily dependent on social facilities provided within the environment. One of the most important facilities is transportations. Study on transportation mode in an urban area is especially very important because for almost every individual living in a large and densely populated area, mobility is one of the most crucial issues in everyday life. Enhance mobility, faster journey to work and less pollution from petrol-propelled vehicles can increase the quality of life, which in turn lead to a sustainable urban living. The study present transportation mode usage issues faced by community related to quality of life in an urban area. This study identifies several issues of transportation mode in urban areas and its impact on the quality of life. The study areas are Putrajaya, Kuala Lumpur and Bandar Kajang, Selangor. The methodology used in this research is secondary and primary data. The questionnaires for the survey were distributed from May 2008 to Jun 2008. These researches were conducted on 144 respondents for to evaluate their perception of transportation mode correlated to the quality of life. The collected data were then analyzed using “Statistical Packages for the Social Science” (SPSS. The respondents comprise of 61 males and 84 females from the age group of 18 to 57 years. This study identifies the percentage of public transportation mode usage in urban area, such as buses (16.7%, train (ERL, monorail and commuter-6.4%; which is very low compared to owning personal car (45.8% and motorcycle (25.4%.The result shows owning personal car is the highest (45.8% in three study areas and monorail and taxi are the lowest (1.4%. The Chi Square Test shows that among the mode transportation with traffic jam is quite difference in Kuala Lumpur, Putrajaya and Kajang. Analysis of the Chi Square Test shows the result is 0.000 (two sides to respondent answering “yes” and analysis of Spearman

  4. A Mathematical Model of Solute Coupled Water Transport in Toad Intestine Incorporating Recirculation of the Actively Transported Solute

    DEFF Research Database (Denmark)

    Larsen, Erik Hviid; Sørensen, Jakob Balslev; Sørensen, Jens Nørkær

    2000-01-01

    those of tight junction and interspace basement membrane by convection-diffusion. With solute permeability of paracellular pathway large relative to paracellular water flow, the paracellular flux ratio of the solute (influx/outflux) is small (2-4) in agreement with experiments. The virtual solute......A mathematical model of an absorbing leaky epithelium is developed for analysis of solute coupled water transport. The non-charged driving solute diffuses into cells and is pumped from cells into the lateral intercellular space (lis). All membranes contain water channels with the solute passing...... increases with hydraulic conductance of the pathway carrying water from mucosal solution into lis. Uphill water transport is accomplished, but with high hydraulic conductance of cell membranes strength of transport is obscured by water flow through cells. Anomalous solvent drag occurs when back flux...

  5. Scaling and predicting solute transport processes in streams

    Science.gov (United States)

    R. González-Pinzón; R. Haggerty; M. Dentz

    2013-01-01

    We investigated scaling of conservative solute transport using temporal moment analysis of 98 tracer experiments (384 breakthrough curves) conducted in 44 streams located on five continents. The experiments span 7 orders of magnitude in discharge (10-3 to 103 m3/s), span 5 orders of magnitude in...

  6. The solute carrier 6 family of transporters

    DEFF Research Database (Denmark)

    Bröer, Stefan; Gether, Ulrik

    2012-01-01

    of these transporters is associated with a variety of diseases. Pharmacological inhibition of the neurotransmitter transporters in this family is an important strategy in the management of neurological and psychiatric disorders. This review provides an overview of the biochemical and pharmacological properties......The solute carrier 6 (SLC6) family of the human genome comprises transporters for neurotransmitters, amino acids, osmolytes and energy metabolites. Members of this family play critical roles in neurotransmission, cellular and whole body homeostasis. Malfunction or altered expression...... of the SLC6 family transporters....

  7. Radioactive materials transport experience

    International Nuclear Information System (INIS)

    Langhaar, J.W.

    1976-01-01

    This paper presents a brief review of the kinds of packaging suitable for different types of waste, the roles of highway and rail transport, restrictions imposed by political entities and carriers, and safety. The U. S. accident record is described, with some statistics given

  8. Mass transport in polyelectrolyte solutions

    Science.gov (United States)

    Schipper, F. J. M.; Leyte, J. C.

    1999-02-01

    The self-diffusion coefficients of the three components of a salt-free heavy-water solution of polymethacrylic acid, completely neutralized with tetra-methylammonium hydroxide, were measured over a broad concentration range. Three concentration regions were observed for the self-diffusion of both the polyions and the counterions. At polyion concentrations below 0.01 mol monomer kg-1, the dilute concentration regime for the polymer, the polyion self-diffusion coefficient approaches the self-diffusion coefficient of a freely diffusing rod upon dilution. At polyelectrolyte concentrations above 0.1 mol monomer kg-1, the self-diffusion coefficients of the solvent, the counterions and the polymer decreased with concentration, suggesting that this decrease is due to a topological constraint on the motions of the components. In the intermediate-concentration region, the self-diffusion coefficients of the polyions and the counterions are independent of the concentration. The polyion dynamic behaviour is, in the intermediate- and high-concentration regions, reasonably well described by that of a hard sphere, with a radius of 3.7 nm. A correct prediction for the solvent dynamics is given by the obstruction effect of this hard sphere on the solvent. The relative counterion self-diffusion coefficient is predicted almost quantitatively over the entire concentration range with the Poisson-Boltzmann-Smoluchowski model for the spherical cell, provided that the sphere radius and the number of charges are chosen appropriately (approximately the number of charges in a persistence length). Using this model, the dependence of the counterion self-diffusion coefficient on the ionic strength, polyion concentration and counterion radius is calculated quantitatively over a large concentration range.

  9. Analysis of Proton Transport Experiments.

    Science.gov (United States)

    1980-09-05

    which can inhibit transport, may grow . The abrupt loss of transport at higher currents in the small channel suggests this possibility. Future experiments... Unicorn Park Drive Woburn, MA 01801 Attn: H. Linnerud 1 copy Lawrence Livermore Laboratory P. 0. Box 808 Livermore, CA 94550 Attn: R. J. Briggs 1 copy R

  10. The Grimsel radionuclide migration experiment - a contribution to raising confidence in the validity of solute transport models used in performance assessment

    International Nuclear Information System (INIS)

    Frick, U.

    1995-01-01

    The safety assessment of radioactive waste repositories is to provide confidence that the predictive models utilized are applicable for the specific repository systems. Nagra has carried out radionuclide migration experiments at the Grimsel underground test site (Switzerland) for testing of currently used methodologies, data bases, conceptual approaches and codes for modeling radionuclide transport through fractured host rocks. Specific objectives included: identification of the relevant transport processes, to test the extrapolation of laboratory sorption data to field conditions, and to demonstrate the applicability of currently used methodology for conceptualizing or building realistic transport models. Field tests and transport modeling work are complemented by an extensive laboratory program. The field experimental activities focused predominantly on establishing appropriate conditions for identifying relevant transport mechanisms on the scale of a few meters, aiming at full recovery of injected tracers, simple geometry and long-term stability of induced dipole flow fields. A relatively simple homogeneous, dual-porosity advection/diffusion model was built with input from a state of the art petrographic characterisation of the water conducting feature. It was possible to calibrate the model from conservative tracer breakthrough curves. (J.S.). 21 refs., 14 figs., 4 tabs

  11. Transnucleaire's experience in maritime transportation

    International Nuclear Information System (INIS)

    Vallette-Fontaine, M.

    1998-01-01

    Since the INF code requirement has been implemented in early 1995 laying down stringent requirements for ships transporting irradiated nuclear fuel, plutonium and high level radioactive waste, Transnucleaire has upgraded and operates two sister ships belonging a CMN shipping company and is well involved in the maritime transportation of radioactive materials. This paper aims at analysing the various principles implemented by Transnucleaire: operate ships such as Bouguenais and Beaulieu in compliance will all existing regulations such as INF Code, Japanese KAISA...; keep the sea transportation of nuclear material at affordable price for all nuclear organizations especially those involved in research activities; avoid for non routine transports, the use of nuclear dedicated ships often precluded by its high costs; adapt the means to all possible evolutions, i.e. be prepared to offer improved ships to satisfy all the scale of requirements; find optimised technical solutions to comply with Japanese type B ship regulations at a reasonable cost. (authors)

  12. Solute transport in aggregated and layered porous media

    International Nuclear Information System (INIS)

    Koch, S.

    1993-01-01

    This work is a contribution to research in soil physics dealing with solute transport in porous media. The influence of structural inhomogeneities on solute transport is investigated. Detailed experiments at the laboratory scale are used to enlighten distinct processes which cannot be studied separately at field scale. Two main aspects are followed up: (i) to show the influence of aggregation of a porous medium on breakthrough time and spreading of an inert tracer and consequences on the estimation of parameter values of models describing solute transport in aggregated systems, (ii) to investigate the influences on the dispersion process when stratification is perpendicular to the direction of flow. Several concepts of modelling solute transport in soil are discussed. Models based on the convection-dispersion equation (CDE) are emphasized because they are used here to model solute transport experiments conducted with aggregated porous media. Stochastic concepts are introduced to show the limitations of the deterministic CDE approaches. Experiments are done in columns containing two kinds of solid phases and were saturated with water. The solid phases are porous and solid glass beads exhibiting a distinctly unimodal or bimodal pore size distribution. Experimental breakthrough curves (BTCs) are modelled with the CDE, a bicontinuum model with a phenomenological mass transfer rate and a bicontinuum spherical diffusion model. Experiments are also done in columns that are unsaturated containing porous materials that are layered. Flow is made at a steady rate. It is shown that layer boundaries have a severe influence on lateral mixing. They may force streamlines to converge or cause a lateral redistribution of solutes. (author) figs., tabs., 122 refs

  13. Electrolyte solution transport in electropolar nanotubes

    International Nuclear Information System (INIS)

    Zhao Jianbing; Culligan, Patricia J; Chen Xi; Qiao Yu; Zhou Qulan; Li Yibing; Tak, Moonho; Park, Taehyo

    2010-01-01

    Electrolyte transport in nanochannels plays an important role in a number of emerging areas. Using non-equilibrium molecular dynamics (NEMD) simulations, the fundamental transport behavior of an electrolyte/water solution in a confined model nanoenvironment is systematically investigated by varying the nanochannel dimension, solid phase, electrolyte phase, ion concentration and transport rate. It is found that the shear resistance encountered by the nanofluid strongly depends on these material/system parameters; furthermore, several effects are coupled. The mechanisms of the nanofluidic transport characteristics are explained by considering the unique molecular/ion structure formed inside the nanochannel. The lower shear resistance observed in some of the systems studies could be beneficial for nanoconductors, while the higher shear resistance (or higher effective viscosity) observed in other systems might enhance the performance of energy dissipation devices.

  14. Reexamining ultrafiltration and solute transport in groundwater

    Science.gov (United States)

    Neuzil, C. E.; Person, Mark

    2017-06-01

    Geologic ultrafiltration—slowing of solutes with respect to flowing groundwater—poses a conundrum: it is consistently observed experimentally in clay-rich lithologies, but has been difficult to identify in subsurface data. Resolving this could be important for clarifying clay and shale transport properties at large scales as well as interpreting solute and isotope patterns for applications ranging from nuclear waste repository siting to understanding fluid transport in tectonically active environments. Simulations of one-dimensional NaCl transport across ultrafiltering clay membrane strata constrained by emerging data on geologic membrane properties showed different ultrafiltration effects than have often been envisioned. In relatively high-permeability advection-dominated regimes, salinity increases occurred mostly within membrane units while their effluent salinity initially fell and then rose to match solute delivery. In relatively low-permeability diffusion-dominated regimes, salinity peaked at the membrane upstream boundary and effluent salinity remained low. In both scenarios, however, only modest salinity changes (up to ˜3 g L-1) occurred because of self-limiting tendencies; membrane efficiency declines as salinity rises, and although sediment compaction increases efficiency, it is also decreases permeability and allows diffusive transport to dominate. It appears difficult for ultrafiltration to generate brines as speculated, but widespread and less extreme ultrafiltration effects in the subsurface could be unrecognized. Conditions needed for ultrafiltration are present in settings that include topographically-driven flow systems, confined aquifer systems subjected to injection or withdrawal, compacting basins, and accretionary complexes.

  15. Pathogen transport in groundwater systems: contrasts with traditional solute transport

    Science.gov (United States)

    Hunt, Randall J.; Johnson, William P.

    2017-06-01

    Water quality affects many aspects of water availability, from precluding use to societal perceptions of fit-for-purpose. Pathogen source and transport processes are drivers of water quality because they have been responsible for numerous outbreaks resulting in large economic losses due to illness and, in some cases, loss of life. Outbreaks result from very small exposure (e.g., less than 20 viruses) from very strong sources (e.g., trillions of viruses shed by a single infected individual). Thus, unlike solute contaminants, an acute exposure to a very small amount of contaminated water can cause immediate adverse health effects. Similarly, pathogens are larger than solutes. Thus, interactions with surfaces and settling become important even as processes important for solutes such as diffusion become less important. These differences are articulated in "Colloid Filtration Theory", a separate branch of pore-scale transport. Consequently, understanding pathogen processes requires changes in how groundwater systems are typically characterized, where the focus is on the leading edges of plumes and preferential flow paths, even if such features move only a very small fraction of the aquifer flow. Moreover, the relatively short survival times of pathogens in the subsurface require greater attention to very fast (solute transport mechanisms discussed here, a more encompassing view of water quality and source water protection is attained. With this more holistic view and theoretical understanding, better evaluations can be made regarding drinking water vulnerability and the relation between groundwater and human health.

  16. Exact solution of the neutron transport equation in spherical geometry

    Energy Technology Data Exchange (ETDEWEB)

    Anli, Fikret; Akkurt, Abdullah; Yildirim, Hueseyin; Ates, Kemal [Kahramanmaras Suetcue Imam Univ. (Turkey). Faculty of Sciences and Letters

    2017-03-15

    Solution of the neutron transport equation in one dimensional slab geometry construct a basis for the solution of neutron transport equation in a curvilinear geometry. Therefore, in this work, we attempt to derive an exact analytical benchmark solution for both neutron transport equations in slab and spherical medium by using P{sub N} approximation which is widely used in neutron transport theory.

  17. Nonrelativistic grey Sn-transport radiative-shock solutions

    International Nuclear Information System (INIS)

    Ferguson, J. M.; Morel, J. E.; Lowrie, R. B.

    2017-01-01

    We present semi-analytic radiative-shock solutions in which grey Sn-transport is used to model the radiation, and we include both constant cross sections and cross sections that depend on temperature and density. These new solutions solve for a variable Eddington factor (VEF) across the shock domain, which allows for interesting physics not seen before in radiative-shock solutions. Comparisons are made with the grey nonequilibrium-diffusion radiative-shock solutions of Lowrie and Edwards [1], which assumed that the Eddington factor is constant across the shock domain. It is our experience that the local Mach number is monotonic when producing nonequilibrium-diffusion solutions, but that this monotonicity may disappear while integrating the precursor region to produce Sn-transport solutions. For temperature- and density-dependent cross sections we show evidence of a spike in the VEF in the far upstream portion of the radiative-shock precursor. We show evidence of an adaptation zone in the precursor region, adjacent to the embedded hydrodynamic shock, as conjectured by Drake [2, 3], and also confirm his expectation that the precursor temperatures adjacent to the Zel’dovich spike take values that are greater than the downstream post-shock equilibrium temperature. We also show evidence that the radiation energy density can be nonmonotonic under the Zel’dovich spike, which is indicative of anti-diffusive radiation flow as predicted by McClarren and Drake [4]. We compare the angle dependence of the radiation flow for the Sn-transport and nonequilibriumdiffusion radiation solutions, and show that there are considerable differences in the radiation flow between these models across the shock structure. Lastly, we analyze the radiation flow to understand the cause of the adaptation zone, as well as the structure of the Sn-transport radiation-intensity solutions across the shock structure.

  18. Numerical solution of the radionuclide transport equation

    International Nuclear Information System (INIS)

    Hadermann, J.; Roesel, F.

    1983-11-01

    A numerical solution of the one-dimensional geospheric radionuclide chain transport equation based on the pseudospectral method is developed. The advantages of this approach are flexibility in incorporating space and time dependent migration parameters, arbitrary boundary conditions and solute rock interactions as well as efficiency and reliability. As an application the authors investigate the impact of non-linear sorption isotherms on migration in crystalline rock. It is shown that non-linear sorption, in the present case a Freundlich isotherm, may reduce concentration at the geosphere outlet by orders of magnitude provided the migration time is comparable or larger than the half-life of the nuclide in question. The importance of fixing dispersivity within the continuum approach is stressed. (Auth.)

  19. Coupled geochemical and solute transport code development

    International Nuclear Information System (INIS)

    Morrey, J.R.; Hostetler, C.J.

    1985-01-01

    A number of coupled geochemical hydrologic codes have been reported in the literature. Some of these codes have directly coupled the source-sink term to the solute transport equation. The current consensus seems to be that directly coupling hydrologic transport and chemical models through a series of interdependent differential equations is not feasible for multicomponent problems with complex geochemical processes (e.g., precipitation/dissolution reactions). A two-step process appears to be the required method of coupling codes for problems where a large suite of chemical reactions must be monitored. Two-step structure requires that the source-sink term in the transport equation is supplied by a geochemical code rather than by an analytical expression. We have developed a one-dimensional two-step coupled model designed to calculate relatively complex geochemical equilibria (CTM1D). Our geochemical module implements a Newton-Raphson algorithm to solve heterogeneous geochemical equilibria, involving up to 40 chemical components and 400 aqueous species. The geochemical module was designed to be efficient and compact. A revised version of the MINTEQ Code is used as a parent geochemical code

  20. Transport of reactive and nonreactive solutes

    International Nuclear Information System (INIS)

    Garabedian, S.P.; Leblanc, D.R.

    1990-01-01

    A natural-gradient tracer test was conducted on Cape Cod, Massachusetts, to examine the transport and dispersion of solutes in a sand and gravel aquifer. A nonreactive tracer, bromide, and two reactive tracers, lithium and molybdate, were injected as a pulse in July 1985 and monitored in three dimensions for 3 years as they moved 280 meters downgradient through an array of multilevel samplers. The tracer transport was quantified using spatial moments. The calculated total mass of bromide for each sampling date varied from 86 to 105 percent of the injected mass, and the center of mass moved at a nearly constant horizontal velocity of 0.42 meters per day. The bromide cloud also moved downward about 4 meters, probably because of density-induced sinking and accretion of areal recharge from precipitation. After 200 meters of transport, the bromide cloud was more than 80 meters long but only 14 meters wide and 6 meters thick. The change in longitudinal dispersivity had reached a constant value (0.96 meters). The transverse horizontal and transverse vertical dispersivities were much smaller (1.8 centimeters and 1.5 millimeters, respectively) than the longitudinal value. The lithium and molybdate clouds followed the same path as the bromide cloud, but a significant amount of their mass was adsorbed onto the aquifer sediments, and their rates of movement were retarded about 50 percent relative to the bromide movement. (Author) (5 figs., 23 refs.)

  1. Transport of organic solutes through amorphous teflon AF films.

    Science.gov (United States)

    Zhao, Hong; Zhang, Jie; Wu, Nianqiang; Zhang, Xu; Crowley, Katie; Weber, Stephen G

    2005-11-02

    Fluorous media have great potential for selective extraction (e.g., as applied to organic synthesis). Fluorous polymer films would have significant advantages in fluorous separations. Stable films of Teflon AF 2400 were cast from solution. Films appear defect-free (SEM; AFM). Rigid aromatic solutes are transported (from chloroform solution to chloroform receiving phase) in a size-dependent manner (log permeability is proportional to -0.0067 times critical volume). Benzene's permeability is about 2 orders of magnitude higher than in comparable gas-phase experiments. The films show selectivity for fluorinated solutes in comparison to the hydrogen-containing control. Transport rates are dependent on the solvent making up the source and receiving phases. The effect of solvent is, interestingly, not due to changes in partition ratio, but rather it is due to changes in the solute diffusion coefficient in the film. Solvents plasticize the films. A less volatile compound, -COOH-terminated poly(hexafluoropropylene oxide) (4), plasticizes the films (T(g) = -40 degrees C). Permeabilities are decreased in comparison to 4-free films apparently because of decreased diffusivity of solutes. The slope of dependence of log permeability on critical volume is not changed, however.

  2. Transport analysis of TFTR experiments

    International Nuclear Information System (INIS)

    Goldston, R.; McCune, D.; Zarnstorff, M.; Hammett, G.; Scott, S.

    1991-01-01

    The purpose of this investigation was to complete the analysis of TFTR data which was under progress. The main emphasis was to study the effects of heating profile and resulting density and temperature profiles on transport through the comparison between beam heated plasmas with hollow and centrally peaked heating profiles (edge vs. center heating). The analysis has been completed and a manuscript has been prepared for publication in Nuclear Fusion. A proposal to perform a similar experiment using ICRF heating to decouple heating profile effects from density profile effects was submitted and was approved by the TFTR. ICRF heating enables the heating profile and the power partition between ions and electrons to be controlled. The experiment was scheduled twice, but it had to be postponed both times

  3. Simulation and experiment of the unsteady heat transport in the onset time of nucleation and crystallization of ice from the subcooled solution

    Energy Technology Data Exchange (ETDEWEB)

    Qin, F.G.F.; Jian Chao Zhao; Russell, A.B.; Xiao Dong Chen; Chen, J.J. [University of Auckland (New Zealand). Dept. of Chemical and Materials Engineering; Robertson, L. [Fonterra Research Centre, Palmerston North (New Zealand)

    2003-08-01

    Heat transfer is an unsteady process in the initial period of ice nucleation or phase transition from aqueous solution. During this period the latent heat of freezing increases the temperature in bulk solution monotonously until the system reaches equilibrium. Meanwhile heat can transfer from the solution to the environment or vise versa. The analysis of this unsteady heat transfer process leads to the establishment of a mathematical model, which is represented by two simultaneous differential equations. Using the Laplace transform and inverse transform, and incorporating the initial condition of ice nucleation, we obtained an analytical solution of this model. Further discussion of the model's fitness by comparing to the experimental data leads to a recognition that ice fouling (or ice adhesion) on the cooler wall should be highlighted in estimating the heat transfer resistance at the very beginning of the ice formation. The model fits to the experimental data satisfactorily. (author)

  4. Geological entropy and solute transport in heterogeneous porous media

    Science.gov (United States)

    Bianchi, Marco; Pedretti, Daniele

    2017-06-01

    We propose a novel approach to link solute transport behavior to the physical heterogeneity of the aquifer, which we fully characterize with two measurable parameters: the variance of the log K values (σY2), and a new indicator (HR) that integrates multiple properties of the K field into a global measure of spatial disorder or geological entropy. From the results of a detailed numerical experiment considering solute transport in K fields representing realistic distributions of hydrofacies in alluvial aquifers, we identify empirical relationship between the two parameters and the first three central moments of the distributions of arrival times of solute particles at a selected control plane. The analysis of experimental data indicates that the mean and the variance of the solutes arrival times tend to increase with spatial disorder (i.e., HR increasing), while highly skewed distributions are observed in more orderly structures (i.e., HR decreasing) or at higher σY2. We found that simple closed-form empirical expressions of the bivariate dependency of skewness on HR and σY2 can be used to predict the emergence of non-Fickian transport in K fields considering a range of structures and heterogeneity levels, some of which based on documented real aquifers. The accuracy of these predictions and in general the results from this study indicate that a description of the global variability and structure of the K field in terms of variance and geological entropy offers a valid and broadly applicable approach for the interpretation and prediction of transport in heterogeneous porous media.

  5. One-dimensional spatially dependent solute transport in semi ...

    African Journals Online (AJOL)

    Initially porous domain is considered solute free and the input source condition is ... parameters for description of solute transport in porous media. ... flow assuming uniform initial concentration with first and third type boundary conditions. Aral.

  6. Solute transport in fractured rock - applications to radionuclide waste repositories

    International Nuclear Information System (INIS)

    Neretnieks, I.

    1990-12-01

    Flow and solute transport in fractured rocks has been intensively studied in the last decade. The increased interest is mainly due to the plans in many countries to site repositories for high level nuclear waste in deep geologic formations. All investigated crystalline rocks have been found to be fractured and most of the water flows in the fractures and fracture zones. The water transports dissolved species and radionuclides. It is thus of interest to be able to understand and to do predictive modelling of the flowrate of water, the flowpaths and the residence times of the water and of the nuclides. The dissolved species including the nuclides will interact with the surrounding rock in different ways and will in many cases be strongly retarded relative to the water velocity. Ionic species may be ion exchanged or sorbed in the mineral surfaces. Charges and neutral species may diffuse into the stagnant waters in the rock matrix and thus be withdrawn from the mobile water. These effects will be strongly dependent on how much rock surface is in contact with the flowing water. It has been found in a set of field experiments and by other observations that not all fractures conduct water. Furthermore it is found that conductive fractures only conduct the water in a small part of the fracture in what is called channels or preferential flowpaths. This report summarizes the present concepts of water flow and solute transport in fractured rocks. The data needs for predictive modelling are discussed and both field and laboratory measurement which have been used to obtain data are described. Several large scale field experiments which have been specially designed to study flow and tracer transport in crystalline rocks are described. In many of the field experients new techniques have been developed and used. (81 refs.) (author)

  7. A quasilinear model for solute transport under unsaturated flow

    International Nuclear Information System (INIS)

    Houseworth, J.E.; Leem, J.

    2009-01-01

    We developed an analytical solution for solute transport under steady-state, two-dimensional, unsaturated flow and transport conditions for the investigation of high-level radioactive waste disposal. The two-dimensional, unsaturated flow problem is treated using the quasilinear flow method for a system with homogeneous material properties. Dispersion is modeled as isotropic and is proportional to the effective hydraulic conductivity. This leads to a quasilinear form for the transport problem in terms of a scalar potential that is analogous to the Kirchhoff potential for quasilinear flow. The solutions for both flow and transport scalar potentials take the form of Fourier series. The particular solution given here is for two sources of flow, with one source containing a dissolved solute. The solution method may easily be extended, however, for any combination of flow and solute sources under steady-state conditions. The analytical results for multidimensional solute transport problems, which previously could only be solved numerically, also offer an additional way to benchmark numerical solutions. An analytical solution for two-dimensional, steady-state solute transport under unsaturated flow conditions is presented. A specific case with two sources is solved but may be generalized to any combination of sources. The analytical results complement numerical solutions, which were previously required to solve this class of problems.

  8. Transport studies for ignition experiments

    International Nuclear Information System (INIS)

    Nocentini, A.; Schultz, G.

    1990-07-01

    The results of a predictive study of plasma energy confinement in IGNITOR, performed with a 1 1/2-D transport code and the Tang an Redi transport model, are reported. For comparison, performance predictions for NET adopting similar assumptions on plasma transport are also presented. (author) 16 figs., 5 tabs., 13 refs

  9. Quantifying solute transport processes: are chemically "conservative" tracers electrically conservative?

    Science.gov (United States)

    Singha, Kamini; Li, Li; Day-Lewis, Frederick D.; Regberg, Aaron B.

    2012-01-01

    The concept of a nonreactive or conservative tracer, commonly invoked in investigations of solute transport, requires additional study in the context of electrical geophysical monitoring. Tracers that are commonly considered conservative may undergo reactive processes, such as ion exchange, thus changing the aqueous composition of the system. As a result, the measured electrical conductivity may reflect not only solute transport but also reactive processes. We have evaluated the impacts of ion exchange reactions, rate-limited mass transfer, and surface conduction on quantifying tracer mass, mean arrival time, and temporal variance in laboratory-scale column experiments. Numerical examples showed that (1) ion exchange can lead to resistivity-estimated tracer mass, velocity, and dispersivity that may be inaccurate; (2) mass transfer leads to an overestimate in the mobile tracer mass and an underestimate in velocity when using electrical methods; and (3) surface conductance does not notably affect estimated moments when high-concentration tracers are used, although this phenomenon may be important at low concentrations or in sediments with high and/or spatially variable cation-exchange capacity. In all cases, colocated groundwater concentration measurements are of high importance for interpreting geophysical data with respect to the controlling transport processes of interest.

  10. Analysis of solute transport in plants using positron emission tomography

    International Nuclear Information System (INIS)

    Partelova, D.

    2016-01-01

    In the first part of the work, geometrically and radiochemically characterized standards (phantoms) imitating the plant tissues and allowing the exact quantification of visualised radioindicator in plant tissues were designed and prepared within the study of visual and analytical characteristics of used positron emission tomograph (microPET system) commercially developed for animal objects at visualization of thin objects. Individual experiments carried out by exposure of excised leaves of tobacco (Nicotiana tabacum L.) or radish (Raphanus sativus L.) in solutions of 2-deoxy-2-fluoro-D-glucose labelled with positron emitter 18 F (2-[ 18 F]FDG) containing 10-, 100-, or 1000-times higher concentrations of D-glucose (c glu ) in comparison with the original 2-[ 18 F]FDG solution showed that the significant changes in visualisation of 2-[ 18 F]FDG distribution as well as in chemical portion of 2-[ 18 F]FDG within the leaf blade were observed as result of increased c glu . In the experiments with the whole plants of tobacco or radish exposed in 2-[ 18 F]FDG solution through the root system, only minimal translocation of 18 F radioactivity into the above-ground parts of plants, also in the case of increased c glu , was observed, which suggest the role of root system as a selective barrier of 2-[ 18 F]FDG transport from roots to the above-ground parts. On the basis of mentioned knowledge and analytical approaches (application of prepared phantoms), the dynamic study of 2-[ 18 F]FDG uptake and transport within the excised leaf of tobacco or whole radish plant was carried out. The description of these processes was realized through the 3D PET images and through the quantification of 2-[ 18 F]FDG distribution within the chosen regions of interest from the point of view of accumulated 18 F radioactivity (in Bq) or amount of D-glucose (in μg) as well. Application of methods of multivariate analysis allows to found the similarities between studied objects mainly from the point

  11. 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 ...

  12. TRANSPORT OF SOLUTES IN THE FIELD AS AFFECTED BY IRRIGATION

    Directory of Open Access Journals (Sweden)

    Alessandro Comegna

    2007-09-01

    Full Text Available This study documents and compares the transport of a conservative solute in near saturated soil profiles under flood and sprinkler irrigation. The experiments were carried out on a clay Vertic-Usthortens soil located near Potenza (Italy. Two 2x2 m2 plots were clipped of their native grass vegetation. After spraying on the surface a Cl- pulse as KCl salt; water was applied in five increments over two months as flood irrigation on the first plot and as sprinkler irrigation on the second one. Chloride resident concentration Cr, was sampled by soil coring at four different days after chemical application. Cr(z,t profiles were analyzed by spatial moment method. The recovered mass of Cl- and location of center of mass were comparable for the two types of irrigation. The spread around the center of mass, however, was higher for the flood-irrigated plot. In the flood-irrigated plot, more mass leached below the depth of 90 cm. The velocity of the center of mass was consistently 10-20% larger than the piston displacement velocity. To evaluate the nature of transport, the Cr(z,t distributions were modelled using quasi-steady solution of convection-dispersion equation(CDE. At the scale of our experiments the profiles of Cl- resident concentration are well-simulated.

  13. Transport of Liquid Phase Organic Solutes in Liquid Crystalline Membranes

    OpenAIRE

    Han, Sangil

    2010-01-01

    Porous cellulose nitrate membranes were impregnated with 8CB and PCH5 LCs (liquid crystals) and separations of solutes dissolved in aqueous phases were performed while monitoring solute concentration via UV-VIS spectrometry. The diffusing organic solutes, which consist of one aromatic ring and various functional groups, were selected to exclude molecular size effects on the diffusion and sorption. We studied the effects on solute transport of solute intra-molecular hydrogen bonding and so...

  14. 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

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

    International Nuclear Information System (INIS)

    Roy Haggerty

    2004-01-01

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

  16. Solution Calorimetry Experiments for Physical Chemistry.

    Science.gov (United States)

    Raizen, Deborah A.; And Others

    1988-01-01

    Presents two experiments: the first one measures the heat of an exothermic reaction by the reduction of permanganate by the ferris ion; the second one measures the heat of an endothermic process, the mixing of ethanol and cyclohexane. Lists tables to aid in the use of the solution calorimeter. (MVL)

  17. Effects of turbulent hyporheic mixing on reach-scale solute transport

    Science.gov (United States)

    Roche, K. R.; Li, A.; Packman, A. I.

    2017-12-01

    Turbulence rapidly mixes solutes and fine particles into coarse-grained streambeds. Both hyporheic exchange rates and spatial variability of hyporheic mixing are known to be controlled by turbulence, but it is unclear how turbulent mixing influences mass transport at the scale of stream reaches. We used a process-based particle-tracking model to simulate local- and reach-scale solute transport for a coarse-bed stream. Two vertical mixing profiles, one with a smooth transition from in-stream to hyporheic transport conditions and a second with enhanced turbulent transport at the sediment-water interface, were fit to steady-state subsurface concentration profiles observed in laboratory experiments. The mixing profile with enhanced interfacial transport better matched the observed concentration profiles and overall mass retention in the streambed. The best-fit mixing profiles were then used to simulate upscaled solute transport in a stream. Enhanced mixing coupled in-stream and hyporheic solute transport, causing solutes exchanged into the shallow subsurface to have travel times similar to the water column. This extended the exponential region of the in-stream solute breakthrough curve, and delayed the onset of the heavy power-law tailing induced by deeper and slower hyporheic porewater velocities. Slopes of observed power-law tails were greater than those predicted from stochastic transport theory, and also changed in time. In addition, rapid hyporheic transport velocities truncated the hyporheic residence time distribution by causing mass to exit the stream reach via subsurface advection, yielding strong exponential tempering in the in-stream breakthrough curves at the timescale of advective hyporheic transport through the reach. These results show that strong turbulent mixing across the sediment-water interface violates the conventional separation of surface and subsurface flows used in current models for solute transport in rivers. Instead, the full distribution of

  18. Transport of Organic Solutes in Clay Formations

    Science.gov (United States)

    The research is a pilot investigation for the SERDP (Strategic Environmental Research and Development Program, DoD) founded project, Impact of Clay-DNAPL Interactions on Transport and Storage of Chlorinated Solvents in Low Permeability Zones, from 2010-2012. The report tries to s...

  19. Effects of Temperature on Solute Transport Parameters in Differently-Textured Soils at Saturated Condition

    Science.gov (United States)

    Hamamoto, S.; Arihara, M.; Kawamoto, K.; Nishimura, T.; Komatsu, T.; Moldrup, P.

    2014-12-01

    Subsurface warming driven by global warming, urban heat islands, and increasing use of shallow geothermal heating and cooling systems such as the ground source heat pump, potentially causes changes in subsurface mass transport. Therefore, understanding temperature dependency of the solute transport characteristics is essential to accurately assess environmental risks due to increased subsurface temperature. In this study, one-dimensional solute transport experiments were conducted in soil columns under temperature control to investigate effects of temperature on solute transport parameters, such as solute dispersion and diffusion coefficients, hydraulic conductivity, and retardation factor. Toyoura sand, Kaolin clay, and intact loamy soils were used in the experiments. Intact loamy soils were taken during a deep well boring at the Arakawa Lowland in Saitama Prefecture, Japan. In the transport experiments, the core sample with 5-cm diameter and 4-cm height was first isotropically consolidated, whereafter 0.01M KCl solution was injected to the sample from the bottom. The concentrations of K+ and Cl- in the effluents were analyzed by an ion chromatograph to obtain solute breakthrough curves. The solute transport parameters were calculated from the breakthrough curves. The experiments were conducted under different temperature conditions (15, 25, and 40 oC). The retardation factor for the intact loamy soils decreased with increasing temperature, while water permeability increased due to reduced viscosity of water at higher temperature. Opposite, the effect of temperature on solute dispersivity for the intact loamy soils was insignificant. The effects of soil texture on the temperature dependency of the solute transport characteristics will be further investigated from comparison of results from differently-textured samples.

  20. Critical experiment study on uranyl nitrate solution experiment facility

    International Nuclear Information System (INIS)

    Zhu Qingfu; Shi Yongqian; Wang Jinrong

    2005-01-01

    The Uranyl Nitrate Solution Experiment Facility was constructed for the research on nuclear criticality safety. In this paper, the configuration of the facility is introduced; a series of critical experiments on uranyl nitrate solution is described later, which were performed for various uranium concentrations under different conditions, i.e. with or without neutron absorbers in the core and with or without water-reflector outside the core. Critical volume and the minimum 235U critical mass for different uranium concentrations are presented. Finally, theoretical analysis is made on the experimental results. (authors)

  1. A variational solution of transport equation based on spherical geometry

    International Nuclear Information System (INIS)

    Liu Hui; Zhang Ben'ai

    2002-01-01

    A variational method with differential forms gives better precision for numerical solution of transport critical problem based on spherical geometry, and its computation seems simple than other approximate methods

  2. Mathematical modeling of fluid and solute transport in peritoneal dialysis

    OpenAIRE

    Waniewski, Jacek

    2001-01-01

    Optimization of peritoneal dialysis schedule and dialysis fluid composition needs, among others, methods for quantitative assessment of fluid and solute transport. Furthermore, an integrative quantitative description of physiological processes within the tissue, which contribute to the net transfer of fluid and solutes, is necessary for interpretation of the data and for predictions of the outcome of possible intervention into the peritoneal transport system. The current pro...

  3. United Kingdom experience in plutonium transportation

    International Nuclear Information System (INIS)

    1978-08-01

    Plutonium has already been transported within the UK over a period of 20 years and to destinations overseas since the early 60's. Experience is recounted with regard to the forms of plutonium transported, regulations, insurance, container design, mode of transport, volume of traffic, physical protection, safety analysis and costs. It is concluded that this traffic could be expanded in the future without danger to the community or the environment

  4. United Kingdom experience in plutonium transportation

    International Nuclear Information System (INIS)

    1978-11-01

    This paper describes the extensive experience of the UKAEA and British Nuclear Fuels Limited in transporting plutonium within the UK over the last 20 years and to destinations overseas since the early 1960s. The aspects covered include: the form of plutonium transported (nitrate, oxide, mixed oxide etc.); UK and international regulations (e.g. covering safety and safeguards matters); insurance; container design; mode of transport; physical protection; and a safety analysis. Costs are estimated to be largely independent of quantity

  5. Mathematical modeling of solute transport in the subsurface

    International Nuclear Information System (INIS)

    Naymik, T.G.

    1987-01-01

    A review of key works on solute transport models indicates that solute transport processes with the exception of advection are still poorly understood. Solute transport models generally do a good job when they are used to test scientific concepts and hypotheses, investigate natural processes, systematically store and manage data, and simulate mass balance of solutes under certain natural conditions. Solute transport models generally are not good for predicting future conditions with a high degree of certainty, or for determining concentrations precisely. The mathematical treatment of solute transport far surpasses their understanding of the process. Investigations of the extent of groundwater contamination and methods to remedy existing problems show the along-term nature of the hazard. Industrial organic compounds may be immiscible in water, highly volatile, or complexed with inorganic as well as other organic compounds; many remain stable in nature almost indefinitely. In the worst case, future disposal of hazardous waste may be restricted to deep burial, as is proposed for radioactive wastes. For investigations pertinent to transport of radionuclides from a geologic repository, the process cannot be fully understood without adequate thermodynamic and kinetic data bases

  6. Solute transport across the articular surface of injured cartilage.

    Science.gov (United States)

    Chin, Hooi Chuan; Moeini, Mohammad; Quinn, Thomas M

    2013-07-15

    Solute transport through extracellular matrix (ECM) is important to physiology and contrast agent-based clinical imaging of articular cartilage. Mechanical injury is likely to have important effects on solute transport since it involves alteration of ECM structure. Therefore it is of interest to characterize effects of mechanical injury on solute transport in cartilage. Using cartilage explants injured by an established mechanical compression protocol, effective partition coefficients and diffusivities of solutes for transport across the articular surface were measured. A range of fluorescent solutes (fluorescein isothiocyanate, 4 and 40kDa dextrans, insulin, and chondroitin sulfate) and an X-ray contrast agent (sodium iodide) were used. Mechanical injury was associated with a significant increase in effective diffusivity versus uninjured explants for all solutes studied. On the other hand, mechanical injury had no effects on effective partition coefficients for most solutes tested, except for 40kDa dextran and chondroitin sulfate where small but significant changes in effective partition coefficient were observed in injured explants. Findings highlight enhanced diffusive transport across the articular surface of injured cartilage, which may have important implications for injury and repair situations. Results also support development of non-equilibrium methods for identification of focal cartilage lesions by contrast agent-based clinical imaging. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. Plasma thermal energy transport: theory and experiments

    International Nuclear Information System (INIS)

    Coppi, B.

    Experiments on the transport across the magnetic field of electron thermal energy are reviewed (Alcator, Frascati Torus). In order to explain the experimental results, a transport model is described that reconfirmed the need to have an expression for the local diffusion coefficient with a negative exponent of the electron temperature

  8. dispersion equation parameters of solute transport in agricultural

    African Journals Online (AJOL)

    Jane

    2011-08-31

    Aug 31, 2011 ... fields for predicting soil quality property. Key words: ... The classical approach of modeling solute transport in porous media uses the deterministic ... concentration of the solution in the liquid phase, u0 is the mean velocity and ...

  9. Temporal moment analysis of solute transport in a coupled fracture ...

    Indian Academy of Sciences (India)

    by considering an inlet boundary condition of constant continuous source in a single fracture. The effect of various fracture-skin parameters like porosity, thickness and ... Study on fluid flow and transport of solute through fractures has been an .... of solutes is happening normal to the direction of flow due to the free molecular.

  10. Isolated effects of external bath osmolality, solute concentration, and electrical charge on solute transport across articular cartilage.

    Science.gov (United States)

    Pouran, Behdad; Arbabi, Vahid; Zadpoor, Amir A; Weinans, Harrie

    2016-12-01

    The metabolic function of cartilage primarily depends on transport of solutes through diffusion mechanism. In the current study, we use contrast enhanced micro-computed tomography to determine equilibrium concentration of solutes through different cartilage zones and solute flux in the cartilage, using osteochondral plugs from equine femoral condyles. Diffusion experiments were performed with two solutes of different charge and approximately equal molecular weight, namely iodixanol (neutral) and ioxaglate (charge=-1) in order to isolate the effects of solute's charge on diffusion. Furthermore, solute concentrations as well as bath osmolality were changed to isolate the effects of steric hindrance on diffusion. Bath concentration and bath osmolality only had minor effects on the diffusion of the neutral solute through cartilage at the surface, middle and deep zones, indicating that the diffusion of the neutral solute was mainly Fickian. The negatively charged solute diffused considerably slower through cartilage than the neutral solute, indicating a large non-Fickian contribution in the diffusion of charged molecules. The numerical models determined maximum solute flux in the superficial zone up to a factor of 2.5 lower for the negatively charged solutes (charge=-1) as compared to the neutral solutes confirming the importance of charge-matrix interaction in diffusion of molecules across cartilage. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

  11. Sustainable freight transport in South Africa:Domestic intermodal solutions

    Directory of Open Access Journals (Sweden)

    Jan H. Havenga

    2011-11-01

    Full Text Available Due to the rapid deregulation of freight transport in South Africa two decades ago, and low historical investment in rail (with resultant poor service delivery, an integrated alternative to road and rail competition was never developed. High national freight logistics costs, significant road infrastructure challenges and environmental impact concerns of a road-dominated freight transport market have, however, fuelled renewed interest in intermodal transport solutions. In this article, a high-level business case for domestic intermodal solutions in South Africa is presented. The results demonstrate that building three intermodal terminals to connect the three major industrial hubs (i.e. Gauteng, Durban and Cape Town through an intermodal solution could reduce transport costs (including externalities for the identified 11.5 million tons of intermodalfriendly freight flows on the Cape and Natal corridors by 42% (including externalities.

  12. Analysis of the Sodium Recirculation Theory of Solute Coupled Water Transport in Small Intestine

    DEFF Research Database (Denmark)

    Larsen, E. H.; Sørensen, Jens Nørkær; Sørensen, J. B.

    2002-01-01

    Our previous mathematical model of solute-coupled water transport through the intestinal epithelium is extended for dealing with electrolytes rather than electroneutral solutes. A 3Na+-2K+ pump in the lateral membranes provides the energy-requiring step for driving transjunctional and translateral......, computations predict that the concentration differences between lis and bathing solutions are small for all three ions. Nevertheless, the diffusion fluxes of the ions out of lis significantly exceed their mass transports. It is concluded that isotonic transport requires recirculation of all three ions....... The computed sodium recirculation flux that is required for isotonic transport corresponds to that estimated in experiments on toad small intestine. This result is shown to be robust and independent of whether the apical entrance mechanism for the sodium ion is a channel, a SGLT1 transporter driving inward...

  13. Determination of chemical solute transport parameters effecting radiostrontium interbed sediments

    International Nuclear Information System (INIS)

    Hemming, C.; Bunde, R.L.; Rosentreter, J.J.

    1993-01-01

    The extent to which radionuclides migrate in an aquifer system is a function of various physical, chemical, and biological processes. A measure of this migration rate is of primary concern when locating suitable storage sites for such species. Parameters including water-rock interactions, infiltration rates, chemical phase modification, and biochemical reactions all affect solute transport. While these different types of chemical reactions can influence solute transport in subsurface waters, distribution coefficients (Kd) can be send to effectively summarize the net chemical factors which dictate transport efficiency. This coefficient describes the partitioning of the solute between the solution and solid phase. Methodology used in determining and interpreting the distribution coefficient for radiostrontium in well characterized sediments will be presented

  14. Semianalytical Solutions of Radioactive or Reactive Transport in Variably-Fractured Layered Media: 1. Solutes

    International Nuclear Information System (INIS)

    George J. Moridis

    2001-01-01

    In this paper, semianalytical solutions are developed for the problem of transport of radioactive or reactive solute tracers through a layered system of heterogeneous fractured media with misaligned fractures. The tracer transport equations in the non-flowing matrix account for (a) diffusion, (b) surface diffusion, (c) mass transfer between the mobile and immobile water fractions, (d) linear kinetic or equilibrium physical, chemical, or combined solute sorption or colloid filtration, and (e) radioactive decay or first-order chemical reactions. The tracer-transport equations in the fractures account for the same processes, in addition to advection and hydrodynamic dispersion. Any number of radioactive decay daughter products (or products of a linear, first-order reaction chain) can be tracked. The solutions, which are analytical in the Laplace space, are numerically inverted to provide the solution in time and can accommodate any number of fractured and/or porous layers. The solutions are verified using analytical solutions for limiting cases of solute and colloid transport through fractured and porous media. The effect of important parameters on the transport of 3 H, 237 Np and 239 Pu (and its daughters) is investigated in several test problems involving layered geological systems of varying complexity

  15. Air medical transportation in India: Our experience.

    Science.gov (United States)

    Khurana, Himanshu; Mehta, Yatin; Dubey, Sunil

    2016-01-01

    Long distance air travel for medical needs is on the increase worldwide. The condition of some patients necessitates specially modified aircraft, and monitoring and interventions during transport by trained medical personnel. This article presents our experience in domestic and international interhospital air medical transportation from January 2010 to January 2014. Hospital records of all air medical transportation undertaken to the institute during the period were analyzed for demographics, primary etiology, and events during transport. 586 patients, 453 (77.3%) males and 133 (22.6%) females of ages 46.7 ± 12.6 years and 53.4 ± 9.7 years were transported by us to the institute. It took 3030 flying hours with an average of 474 ± 72 min for each mission. The most common indication for transport was cardiovascular diseases in 210 (35.8%) and central nervous system disease in 120 (20.4%) cases. The overall complication rate was 5.3% There was no transport related mortality. Cardiac and central nervous system ailments are the most common indication for air medical transportation. These patients may need attention and interventions as any critical patient in the hospital but in a difficult environment lacking space and help. Air medical transport carries no more risk than ground transportation.

  16. Field experiments on airborne moisture transport

    NARCIS (Netherlands)

    Oldengarm, J.; Gids, W.F. de

    1990-01-01

    Within the framework of the Dutch participation in the IEA Annex XIV “Condensation” field experiments have been carried out to study airbome moisture transport in realistic circumstances. The experiments were done in an unoccupied 3-story dwelling in Leidschendam in the Netherlands. Some of the

  17. End-Member Formulation of Solid Solutions and Reactive Transport

    Energy Technology Data Exchange (ETDEWEB)

    Lichtner, Peter C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    A model for incorporating solid solutions into reactive transport equations is presented based on an end-member representation. Reactive transport equations are solved directly for the composition and bulk concentration of the solid solution. Reactions of a solid solution with an aqueous solution are formulated in terms of an overall stoichiometric reaction corresponding to a time-varying composition and exchange reactions, equivalent to reaction end-members. Reaction rates are treated kinetically using a transition state rate law for the overall reaction and a pseudo-kinetic rate law for exchange reactions. The composition of the solid solution at the onset of precipitation is assumed to correspond to the least soluble composition, equivalent to the composition at equilibrium. The stoichiometric saturation determines if the solid solution is super-saturated with respect to the aqueous solution. The method is implemented for a simple prototype batch reactor using Mathematica for a binary solid solution. Finally, the sensitivity of the results on the kinetic rate constant for a binary solid solution is investigated for reaction of an initially stoichiometric solid phase with an undersaturated aqueous solution.

  18. Coupling between solute transport and chemical reactions models

    International Nuclear Information System (INIS)

    Samper, J.; Ajora, C.

    1993-01-01

    During subsurface transport, reactive solutes are subject to a variety of hydrodynamic and chemical processes. The major hydrodynamic processes include advection and convection, dispersion and diffusion. The key chemical processes are complexation including hydrolysis and acid-base reactions, dissolution-precipitation, reduction-oxidation, adsorption and ion exchange. The combined effects of all these processes on solute transport must satisfy the principle of conservation of mass. The statement of conservation of mass for N mobile species leads to N partial differential equations. Traditional solute transport models often incorporate the effects of hydrodynamic processes rigorously but oversimplify chemical interactions among aqueous species. Sophisticated chemical equilibrium models, on the other hand, incorporate a variety of chemical processes but generally assume no-flow systems. In the past decade, coupled models accounting for complex hydrological and chemical processes, with varying degrees of sophistication, have been developed. The existing models of reactive transport employ two basic sets of equations. The transport of solutes is described by a set of partial differential equations, and the chemical processes, under the assumption of equilibrium, are described by a set of nonlinear algebraic equations. An important consideration in any approach is the choice of primary dependent variables. Most existing models cannot account for the complete set of chemical processes, cannot be easily extended to include mixed chemical equilibria and kinetics, and cannot handle practical two and three dimensional problems. The difficulties arise mainly from improper selection of the primary variables in the transport equations. (Author) 38 refs

  19. Fluid transport with time on peritoneal dialysis: the contribution of free water transport and solute coupled water transport

    NARCIS (Netherlands)

    Coester, Annemieke M.; Smit, Watske; Struijk, Dirk G.; Krediet, Raymond T.

    2009-01-01

    Ultrafiltration in peritoneal dialysis occurs through endothelial water channels (free water transport) and together with solutes across small pores: solute coupled water transport. A review is given of cross-sectional studies and on the results of longitudinal follow-up

  20. Prolonged river water pollution due to variable-density flow and solute transport in the riverbed

    Science.gov (United States)

    Jin, Guangqiu; Tang, Hongwu; Li, Ling; Barry, D. A.

    2015-04-01

    A laboratory experiment and numerical modeling were used to examine effects of density gradients on hyporheic flow and solute transport under the condition of a solute pulse input to a river with regular bed forms. Relatively low-density gradients due to an initial salt pulse concentration of 1.55 kg m-3 applied in the experiment were found to modulate significantly the pore-water flow and solute transport in the riverbed. Such density gradients increased downward flow and solute transport in the riverbed by factors up to 1.6. This resulted in a 12.2% increase in the total salt transfer from the water column to the riverbed over the salt pulse period. As the solute pulse passed, the effect of the density gradients reversed, slowing down the release of the solute back to the river water by a factor of 3.7. Numerical modeling indicated that these density effects intensified as salt concentrations in the water column increased. Simulations further showed that the density gradients might even lead to unstable flow and result in solute fingers in the bed of large bed forms. The slow release of solute from the bed back to the river led to a long tail of solute concentration in the river water. These findings have implications for assessment of impact of pollution events on river systems, in particular, long-term effects on both the river water and riverbed due to the hyporheic exchange.

  1. MOX fuel transport: the French experience

    International Nuclear Information System (INIS)

    Sanchis, H.; Verdier, A.; Sanchis, H.

    1999-01-01

    In the back-end of the fuel cycle, several leading countries have chosen the Reprocessing, Conditioning, Recycling (RCR) option. Plutonium recycling in the form of MOX fuel is a mature industry, with successful operational experience and large-scale fabrication plants an several European countries. The COGEMA Group has developed the industrialized products to master the RCR operation including transport COGEMA subsidiary, TRANSNUCLEAIRE has been operating MOX fuel transports on an industrial scale for more than 10 years. In 1998, around 200 transports of Plutonium materials have been organised by TRANSNUCLEAIRE. These transports have been carried out by road between various facilities in Europe: reprocessing plants, manufacturing plants and power plants. The materials transported are either: PuO 2 and MOX powder; BWR and PWR MOX fuel rods; BWR and PWR MOX fuel assemblies. Because MOX fuel transport is subject to specific safety, security and fuel integrity requirements, the MOX fuel transport system implemented by TRANSNUCLEAIRE is fully dedicated. Packaging have been developed, licensed and manufactured for each kind of MOX material in compliance with relevant regulations. A fleet of vehicles qualified according to existing physical protection regulations is operated by TRANSNUCLEAIRE. TRANSNUCLEAIRE has gained a broad experience in MOX transport in 10 years. Technical and operational know-how has been developed and improved for each step: vehicles and packaging design and qualification; vehicle and packaging maintenance; transport operations. Further developments are underway to increase the payload of the packaging and to improve the transport conditions, safety and security remaining of course top priority. (authors)

  2. Centrifuge Techniques and Apparatus for Transport Experiments in Porous Media

    Energy Technology Data Exchange (ETDEWEB)

    Earl D. Mattson; Carl D. Paler; Robert W. Smith; Markus Flury

    2010-06-01

    This paper describes experimental approaches and apparatus that we have developed to study solute and colloid transport in porous media using Idaho National Laboratory's 2-m radius centrifuge. The ex-perimental techniques include water flux scaling with applied acceleration at the top of the column and sub-atmospheric pressure control at the column base, automation of data collection, and remote experimental con-trol over the internet. These apparatus include a constant displacement piston pump, a custom designed liquid fraction collector based on switching valve technology, and modified moisture monitoring equipment. Suc-cessful development of these experimental techniques and equipment is illustrated through application to transport of a conservative tracer through unsaturated sand column, with centrifugal acceleration up to 40 gs. Development of such experimental equipment that can withstand high accelerations enhances the centrifuge technique to conduct highly controlled unsaturated solute/colloid transport experiments and allows in-flight liquid sample collection of the effluent.

  3. Transport Task Force workshop: basic experiments highlights

    Energy Technology Data Exchange (ETDEWEB)

    Linford, R.K. (Los Alamos National Lab., NM (USA)); Luckhardt, S. (Massachusetts Inst. of Tech., Cambridge, MA (USA)); Lyon, J.F. (Oak Ridge National Lab., TN (USA)); Navratil, G.A. (Columbia Univ., New York, NY (USA)); Schoenberg, K.F. (Los Alamos National Lab., NM (USA))

    1990-01-01

    Selected topics are summarized from the Basic Experiments session of the Transport Task Force Workshop held August 21-24, 1989, in San Diego, California. This session included presentations on paradigm experiments, stellarators, reversed-field pinches, and advanced tokamaks. Recent advances in all of these areas illustrate the importance of these experiments in advancing our understanding of toroidal transport. Progress has been made in measuring the details of particle diffusion, isolating specific modes, measuring fluctuation variations with field geometry and beta, and comparing all these with theoretical predictions. The development of experimental tools for determining which fluctuations dominate transport are also reported. Continued significant advances are anticipated in a number of areas highlighted. (author).

  4. Transport Task Force workshop: basic experiments highlights

    International Nuclear Information System (INIS)

    Linford, R.K.; Luckhardt, S.; Lyon, J.F.; Navratil, G.A.; Schoenberg, K.F.

    1990-01-01

    Selected topics are summarized from the Basic Experiments session of the Transport Task Force Workshop held August 21-24, 1989, in San Diego, California. This session included presentations on paradigm experiments, stellarators, reversed-field pinches, and advanced tokamaks. Recent advances in all of these areas illustrate the importance of these experiments in advancing our understanding of toroidal transport. Progress has been made in measuring the details of particle diffusion, isolating specific modes, measuring fluctuation variations with field geometry and beta, and comparing all these with theoretical predictions. The development of experimental tools for determining which fluctuations dominate transport are also reported. Continued significant advances are anticipated in a number of areas highlighted. (author)

  5. Analytical solution to the hybrid diffusion-transport equation

    International Nuclear Information System (INIS)

    Nanneh, M.M.; Williams, M.M.R.

    1986-01-01

    A special integral equation was derived in previous work using a hybrid diffusion-transport theory method for calculating the flux distribution in slab lattices. In this paper an analytical solution of this equation has been carried out on a finite reactor lattice. The analytical results of disadvantage factors are shown to be accurate in comparison with the numerical results and accurate transport theory calculations. (author)

  6. 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.

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

    Science.gov (United States)

    Kim, Yangmin X; Ranathunge, Kosala; Lee, Seulbi; Lee, Yejin; Lee, Deogbae; Sung, Jwakyung

    2018-01-01

    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.

  8. New numerical method for solving the solute transport equation

    International Nuclear Information System (INIS)

    Ross, B.; Koplik, C.M.

    1978-01-01

    The solute transport equation can be solved numerically by approximating the water flow field by a network of stream tubes and using a Green's function solution within each stream tube. Compared to previous methods, this approach permits greater computational efficiency and easier representation of small discontinuities, and the results are easier to interpret physically. The method has been used to study hypothetical sites for disposal of high-level radioactive waste

  9. Efficient solution of a multi objective fuzzy transportation problem

    Science.gov (United States)

    Vidhya, V.; Ganesan, K.

    2018-04-01

    In this paper we present a methodology for the solution of multi-objective fuzzy transportation problem when all the cost and time coefficients are trapezoidal fuzzy numbers and the supply and demand are crisp numbers. Using a new fuzzy arithmetic on parametric form of trapezoidal fuzzy numbers and a new ranking method all efficient solutions are obtained. The proposed method is illustrated with an example.

  10. Stable solutions of nonlocal electron heat transport equations

    International Nuclear Information System (INIS)

    Prasad, M.K.; Kershaw, D.S.

    1991-01-01

    Electron heat transport equations with a nonlocal heat flux are in general ill-posed and intrinsically unstable, as proved by the present authors [Phys. Fluids B 1, 2430 (1989)]. A straightforward numerical solution of these equations will therefore lead to absurd results. It is shown here that by imposing a minimal set of constraints on the problem it is possible to arrive at a globally stable, consistent, and energy conserving numerical solution

  11. Peritoneal fluid transport in CAPD patients with different transport rates of small solutes.

    Science.gov (United States)

    Sobiecka, Danuta; Waniewski, Jacek; Weryński, Andrzej; Lindholm, Bengt

    2004-01-01

    Continuous ambulatory peritoneal dialysis (CAPD) patients with high peritoneal solute transport rate often have inadequate peritoneal fluid transport. It is not known whether this inadequate fluid transport is due solely to a too rapid fall of osmotic pressure, or if the decreased effectiveness of fluid transport is also a contributing factor. To analyze fluid transport parameters and the effectiveness of dialysis fluid osmotic pressure in the induction of fluid flow in CAPD patients with different small solute transport rates. 44 CAPD patients were placed in low (n = 6), low-average (n = 13), high-average (n = 19), and high (n = 6) transport groups according to a modified peritoneal equilibration test (PET). The study involved a 6-hour peritoneal dialysis dwell with 2 L 3.86% glucose dialysis fluid for each patient. Radioisotopically labeled serum albumin was added as a volume marker.The fluid transport parameters (osmotic conductance and fluid absorption rate) were estimated using three mathematical models of fluid transport: (1) Pyle model (model P), which describes ultrafiltration rate as an exponential function of time; (2) model OS, which is based on the linear relationship of ultrafiltration rate and overall osmolality gradient between dialysis fluid and blood; and (3) model G, which is based on the linear relationship between ultrafiltration rate and glucose concentration gradient between dialysis fluid and blood. Diffusive mass transport coefficients (K(BD)) for glucose, urea, creatinine, potassium, and sodium were estimated using the modified Babb-Randerson-Farrell model. The high transport group had significantly lower dialysate volume and glucose and osmolality gradients between dialysate and blood, but significantly higher K(BD) for small solutes compared with the other transport groups. Osmotic conductance, fluid absorption rate, and initial ultrafiltration rate did not differ among the transport groups for model OS and model P. Model G yielded

  12. Simulation of unsaturated flow and nonreactive solute transport in a heterogeneous soil at the field scale

    International Nuclear Information System (INIS)

    Rockhold, M.L.

    1993-02-01

    A field-scale, unsaturated flow and solute transport experiment at the Las Cruces trench site in New Mexico was simulated as part of a ''blind'' modeling exercise to demonstrate the ability or inability of uncalibrated models to predict unsaturated flow and solute transport in spatially variable porous media. Simulations were conducted using a recently developed multiphase flow and transport simulator. Uniform and heterogeneous soil models were tested, and data from a previous experiment at the site were used with an inverse procedure to estimate water retention parameters. A spatial moment analysis was used to provide a quantitative basis for comparing the mean observed and simulated flow and transport behavior. The results of this study suggest that defensible predictions of waste migration and fate at low-level waste sites will ultimately require site-specific data for model calibration

  13. Green transportation logistics: the quest for win-win solutions

    DEFF Research Database (Denmark)

    measures and speed and route optimization; Sulphur emissions; Lifecycle emissions; Green rail transportation; Green air transportation; Green inland navigation and possible areas for further research. Throughout, the book pursues the goal of “win-win” solutions and analyzes the phenomenon of “push......This book examines the state of the art in green transportation logistics from the perspective of balancing environmental performance in the transportation supply chain while also satisfying traditional economic performance criteria. Part of the book is drawn from the recently completed European...... Union project Super Green, a three-year project intended to promote the development of European freight corridors in an environmentally friendly manner. Additional chapters cover both the methodological base and the application context of green transportation logistics. Individual chapters look...

  14. The future of public transport in light of solutions for sustainable transport development

    Directory of Open Access Journals (Sweden)

    Kazimierz LEJDA

    2017-06-01

    Full Text Available The paper highlights possible directions in the development of sustainable public transport solutions. When appropriately identified and implemented, such solutions can contribute to improved quality of urban life by reducing the adverse effects of transport on human health and the natural environment. The paper also raises questions about implementing pedestrian traffic zones, expanding the level of cycling, and introducing a workable parking policy, congestion charges, electromobility and intelligent systems for road traffic management in conurbations.

  15. Transport-constrained extensions of collision and track length estimators for solutions of radiative transport problems

    International Nuclear Information System (INIS)

    Kong, Rong; Spanier, Jerome

    2013-01-01

    In this paper we develop novel extensions of collision and track length estimators for the complete space-angle solutions of radiative transport problems. We derive the relevant equations, prove that our new estimators are unbiased, and compare their performance with that of more conventional estimators. Such comparisons based on numerical solutions of simple one dimensional slab problems indicate the the potential superiority of the new estimators for a wide variety of more general transport problems

  16. GRRR. The EXPECT groundwater model for transport of solutes

    NARCIS (Netherlands)

    Meijers R; Sauter FJ; Veling EJM; van Grinsven JJM; Leijnse A; Uffink GJM; MTV; CWM; LBG

    1994-01-01

    In this report the design and first test results are presented of the EXPECT groundwater module for transport of solutes GRRR (GRoundwater source Receptor Relationships). This model is one of the abiotic compartment modules of the EXPECT model. The EXPECT model is a tool for scenario development

  17. Solute transport modelling with the variable temporally dependent ...

    Indian Academy of Sciences (India)

    Pintu Das

    2018-02-07

    Feb 7, 2018 ... in a finite domain with time-dependent sources and dis- tance-dependent dispersivities. Also, existing ... solute transport in multi-layered porous media using gen- eralized integral transform technique with .... methods for solving the fractional reaction-–sub-diffusion equation. To solve numerically the Eqs.

  18. Chlorovirus-mediated membrane depolarization of Chlorella alters secondary active transport of solutes.

    Science.gov (United States)

    Agarkova, Irina; Dunigan, David; Gurnon, James; Greiner, Timo; Barres, Julia; Thiel, Gerhard; Van Etten, James L

    2008-12-01

    Paramecium bursaria chlorella virus 1 (PBCV-1) is the prototype of a family of large, double-stranded DNA, plaque-forming viruses that infect certain eukaryotic chlorella-like green algae from the genus Chlorovirus. PBCV-1 infection results in rapid host membrane depolarization and potassium ion release. One interesting feature of certain chloroviruses is that they code for functional potassium ion-selective channel proteins (Kcv) that are considered responsible for the host membrane depolarization and, as a consequence, the efflux of potassium ions. This report examines the relationship between cellular depolarization and solute uptake. Annotation of the virus host Chlorella strain NC64A genome revealed 482 putative transporter-encoding genes; 224 are secondary active transporters. Solute uptake experiments using seven radioactive compounds revealed that virus infection alters the transport of all the solutes. However, the degree of inhibition varied depending on the solute. Experiments with nystatin, a drug known to depolarize cell membranes, produced changes in solute uptake that are similar but not identical to those that occurred during virus infection. Therefore, these studies indicate that chlorovirus infection causes a rapid and sustained depolarization of the host plasma membrane and that this depolarization leads to the inhibition of secondary active transporters that changes solute uptake.

  19. Win-Win transportation solutions price reforms with multiple benefits

    International Nuclear Information System (INIS)

    Litman, T.

    2001-01-01

    Reform strategies in the transportation market, such as the Win-Win Transportation Solutions, can provide several economic, social and environmental benefits. The strategies are cost effective, technically feasible reforms based on market principles which help create a more equitable and efficient transportation system that supports sustainable economic development. The benefits they provide include reduced traffic congestion, road and parking facility savings, consumer savings, equity, safety and environmental protection. They also increase economic productivity. If fully implemented, they could reduce motor vehicle impacts by 15 to 30 per cent and could help achieve the Kyoto emission reduction targets. Examples of Win-Win strategies at the federal level include: (1) removal of subsidies to oil production and internalized costs, and (2) tax exempt employer provided transfer benefits. Examples of Win-Win strategies at the state/provincial level include: (1) distance-based vehicle insurance and registration fees, (2) least-coast transportation planning and funding, (3) revenue-neutral tax shifting, (4) road pricing, (5) reform motor carrier regulations for competition and efficiency, (6) local and regional transportation demand management programs, (7) more efficient land use, (8) more flexible zoning requirements, (9) parking cash out, (10) transportation management associations, (11) location-efficient housing and mortgages, (12) school and campus trip management, (13) car sharing, (14) non-motorized transport improvements, and (15) traffic calming. It was noted that any market reform that leads to more efficient use of existing transportation systems can provide better economic development benefits. 9 refs., 1 tab., 1 fig

  20. The separation of radionuclide migration by solution and particle transport in LLRW repository buffer material

    International Nuclear Information System (INIS)

    Torok, J.; Buckley, L.P.; Woods, B.L.

    1989-01-01

    Laboratory-scale lysimeter experiments were performed with simulated waste forms placed in candidate buffer materials which have been chosen for a low-level radioactive waste repository. Radionuclide releases into the effluent water and radionuclide capture by the buffer material were determined. The results could not be explained by traditional solution transport mechanisms, and transport by particles released from the waste form and/or transport by buffer particles were suspected as the dominant mechanism for radionuclide release from the lysimeters. To elucidate the relative contribution of particle and solution transport, the waste forms were replaced by a wafer of neutron-activated buffer soaked with selected soluble isotopes. Particle transport was determined by the movement of gamma-emitting neutron-activation products through the lysimeter. Solution transport was quantified by comparing the migration of soluble radionuclides relative to the transport of neutron activation products. The new approach for monitoring radionuclide migration in soil is presented. It facilitates the determination of most of the fundamental coefficients required to model the transport process

  1. Numerical solution of the transport equation describing the radon transport from subsurface soil to buildings

    International Nuclear Information System (INIS)

    Savovic, S.; Djordjevich, A.; Ristic, G.

    2012-01-01

    A theoretical evaluation of the properties and processes affecting the radon transport from subsurface soil into buildings is presented in this work. The solution of the relevant transport equation is obtained using the explicit finite difference method (EFDM). Results are compared with analytical steady-state solution reported in the literature. Good agreement is found. It is shown that EFDM is effective and accurate for solving the equation that describes radon diffusion, advection and decay during its transport from subsurface to buildings, which is especially important when arbitrary initial and boundary conditions are required. (authors)

  2. Solute transport model for radioisotopes in layered soil

    International Nuclear Information System (INIS)

    Essel, P.

    2010-01-01

    The study considered the transport of a radioactive solute in solution from the surface of the earth down through the soil to the ground water when there is an accidental or intentional spillage of a radioactive material on the surface. The finite difference method was used to model the spatial and temporal profile of moisture content in a soil column using the θ-based Richard's equation leading to solution of the convective-dispersive equation for non-adsorbing solutes numerically. A matlab code has been generated to predict the transport of the radioactive contaminant, spilled on the surface of a vertically heterogeneous soil made up of two layers to determine the residence time of the solute in the unsaturated zone, the time it takes the contaminant to reach the groundwater and the amount of the solute entering the groundwater in various times and the levels of pollution in those times. The model predicted that, then there is a spillage of 7.2g of tritium, on the surface of the ground at the study area, it will take two years for the radionuclide to enter the groundwater and fifteen years to totally leave the unsaturated zone. There is therefore the need to try as much as possible to avoid intentional or accidental spillage of the radionuclide since it has long term effect. (au)

  3. Simulation of transportation of low enriched uranium solutions

    International Nuclear Information System (INIS)

    Hope, E.P.; Ades, M.J.

    1996-01-01

    A simulation of the transportation by truck of low enriched uranium solutions has been completed for NEPA purposes at the Savannah River Site. The analysis involves three distinct source terms, and establishes the radiological risks of shipment to three possible destinations. Additionally, loading accidents were analyzed to determine the radiological consequences of mishaps during handling and delivery. Source terms were developed from laboratory measurements of chemical samples from low enriched uranium feed materials being stored at SRS facilities, and from manufacturer data on transport containers. The transportation simulations were accomplished over the INTERNET using the DOE TRANSNET system at Sandia National Laboratory. The HIGHWAY 3.3 code was used to analyze routing scenarios, and the RADTRAN 4 code was used to analyze incident free and accident risks of transporting radiological materials. Loading accidents were assessed using the Savannah River Site AXAIR89Q and RELEASE 2 codes

  4. The secret to successful solute-transport modeling

    Science.gov (United States)

    Konikow, Leonard F.

    2011-01-01

    Modeling subsurface solute transport is difficult—more so than modeling heads and flows. The classical governing equation does not always adequately represent what we see at the field scale. In such cases, commonly used numerical models are solving the wrong equation. Also, the transport equation is hyperbolic where advection is dominant, and parabolic where hydrodynamic dispersion is dominant. No single numerical method works well for all conditions, and for any given complex field problem, where seepage velocity is highly variable, no one method will be optimal everywhere. Although we normally expect a numerically accurate solution to the governing groundwater-flow equation, errors in concentrations from numerical dispersion and/or oscillations may be large in some cases. The accuracy and efficiency of the numerical solution to the solute-transport equation are more sensitive to the numerical method chosen than for typical groundwater-flow problems. However, numerical errors can be kept within acceptable limits if sufficient computational effort is expended. But impractically long

  5. Water and solute transport across the peritoneal membrane.

    Science.gov (United States)

    Morelle, Johann; Devuyst, Olivier

    2015-09-01

    We review the molecular mechanisms of peritoneal transport and discuss how a better understanding of these mechanisms is relevant for dialysis therapy. Peritoneal dialysis involves diffusion and osmosis through the highly vascularized peritoneal membrane. Computer simulations, expression studies and functional analyses in Aqp1 knockout mice demonstrated the critical role of the water channel aquaporin-1 (AQP1) in water removal during peritoneal dialysis. Pharmacologic regulation of AQP1, either through increased expression or gating, is associated with increased water transport in rodent models of peritoneal dialysis. Water transport is impaired during acute peritonitis, despite unchanged expression of AQP1, resulting from the increased microvascular area that dissipates the osmotic gradient across the membrane. In long-term peritoneal dialysis patients, the fibrotic interstitium also impairs water transport, resulting in ultrafiltration failure. Recent data suggest that stroke and drug intoxications might benefit from peritoneal dialysis and could represent novel applications of peritoneal transport in the future. A better understanding of the regulation of osmotic water transport across the peritoneum offers novel insights into the role of water channels in microvascular endothelia, the functional importance of structural changes in the peritoneal interstitium and the transport of water and solutes across biological membranes in general.

  6. Effects of sorption and temperature on solute transport in unsaturated steady flow

    International Nuclear Information System (INIS)

    Fuentes, H.R.; Polzer, W.L.; Essington, E.H.

    1986-01-01

    It is known that temperature affects physical and chemical processes and that these processes may alter the transport of solutes in the environment. Laboratory column studies were performed in unsaturated flow conditions with a composite pulse containing iodide, cobalt, cesium and strontium each at 10 -3 M. The experiments were performed with Bandelier Tuff and produced breakthrough curves that indicate significant changes in transport due to a temperature change from 25 0 C to 5 0 C for nonconservative solutes. Also, the interpretation of the temperature and sorption data suggest that the differences in transport between 5 0 C and 25 0 C for nonconservative solutes may be predicted in a qualitative manner from batch equilibrium and nonequilibrium sorption data and the theory of sorption used in deriving the modified Freundlich isotherm equation. These effects should be of concern in modeling and management of spills and waste disposal within this range of environmental temperatures

  7. Solution of the transport equation with account for inelastic collisions

    International Nuclear Information System (INIS)

    Kalashnikov, N.P.; Remizovich, V.S.; Ryazanov, M.I.

    1980-01-01

    The theory of charged particle scattering in a matter with account for inelastic collisions is considered. In ''directly-forward'' approximation the transport equation at the absence of elastic collisions is obtained. The solution of the transport equation is made without and with account for fluctuation of energy losses. Formulas for path-energy relation are given. Energy spectrum and distribution of fast charged particles with respect to paths are studied. The problem of quantum mechanical approach to the theory of multiple scattering of fast charged particles in a matter is discussed briefly

  8. From analytical solutions of solute transport equations to multidimensional time-domain random walk (TDRW) algorithms

    Science.gov (United States)

    Bodin, Jacques

    2015-03-01

    In this study, new multi-dimensional time-domain random walk (TDRW) algorithms are derived from approximate one-dimensional (1-D), two-dimensional (2-D), and three-dimensional (3-D) analytical solutions of the advection-dispersion equation and from exact 1-D, 2-D, and 3-D analytical solutions of the pure-diffusion equation. These algorithms enable the calculation of both the time required for a particle to travel a specified distance in a homogeneous medium and the mass recovery at the observation point, which may be incomplete due to 2-D or 3-D transverse dispersion or diffusion. The method is extended to heterogeneous media, represented as a piecewise collection of homogeneous media. The particle motion is then decomposed along a series of intermediate checkpoints located on the medium interface boundaries. The accuracy of the multi-dimensional TDRW method is verified against (i) exact analytical solutions of solute transport in homogeneous media and (ii) finite-difference simulations in a synthetic 2-D heterogeneous medium of simple geometry. The results demonstrate that the method is ideally suited to purely diffusive transport and to advection-dispersion transport problems dominated by advection. Conversely, the method is not recommended for highly dispersive transport problems because the accuracy of the advection-dispersion TDRW algorithms degrades rapidly for a low Péclet number, consistent with the accuracy limit of the approximate analytical solutions. The proposed approach provides a unified methodology for deriving multi-dimensional time-domain particle equations and may be applicable to other mathematical transport models, provided that appropriate analytical solutions are available.

  9. Solute carrier transporters: potential targets for digestive system neoplasms.

    Science.gov (United States)

    Xie, Jing; Zhu, Xiao Yan; Liu, Lu Ming; Meng, Zhi Qiang

    2018-01-01

    Digestive system neoplasms are the leading causes of cancer-related death all over the world. Solute carrier (SLC) superfamily is composed of a series of transporters that are ubiquitously expressed in organs and tissues of digestive systems and mediate specific uptake of small molecule substrates in facilitative manner. Given the important role of SLC proteins in maintaining normal functions of digestive system, dysregulation of these protein in digestive system neoplasms may deliver biological and clinical significance that deserves systemic studies. In this review, we critically summarized the recent advances in understanding the role of SLC proteins in digestive system neoplasms. We highlighted that several SLC subfamilies, including metal ion transporters, transporters of glucose and other sugars, transporters of urea, neurotransmitters and biogenic amines, ammonium and choline, inorganic cation/anion transporters, transporters of nucleotide, amino acid and oligopeptide organic anion transporters, transporters of vitamins and cofactors and mitochondrial carrier, may play important roles in mediating the initiation, progression, metastasis, and chemoresistance of digestive system neoplasms. Proteins in these SLC subfamilies may also have diagnostic and prognostic values to particular cancer types. Differential expression of SLC proteins in tumors of digestive system was analyzed by extracting data from human cancer database, which revealed that the roles of SLC proteins may either be dependent on the substrates they transport or be tissue specific. In addition, small molecule modulators that pharmacologically regulate the functions of SLC proteins were discussed for their possible application in the treatment of digestive system neoplasms. This review highlighted the potential of SLC family proteins as drug target for the treatment of digestive system neoplasms.

  10. Continuous time random walk analysis of solute transport in fractured porous media

    Energy Technology Data Exchange (ETDEWEB)

    Cortis, Andrea; Cortis, Andrea; Birkholzer, Jens

    2008-06-01

    The objective of this work is to discuss solute transport phenomena in fractured porous media, where the macroscopic transport of contaminants in the highly permeable interconnected fractures can be strongly affected by solute exchange with the porous rock matrix. We are interested in a wide range of rock types, with matrix hydraulic conductivities varying from almost impermeable (e.g., granites) to somewhat permeable (e.g., porous sandstones). In the first case, molecular diffusion is the only transport process causing the transfer of contaminants between the fractures and the matrix blocks. In the second case, additional solute transfer occurs as a result of a combination of advective and dispersive transport mechanisms, with considerable impact on the macroscopic transport behavior. We start our study by conducting numerical tracer experiments employing a discrete (microscopic) representation of fractures and matrix. Using the discrete simulations as a surrogate for the 'correct' transport behavior, we then evaluate the accuracy of macroscopic (continuum) approaches in comparison with the discrete results. However, instead of using dual-continuum models, which are quite often used to account for this type of heterogeneity, we develop a macroscopic model based on the Continuous Time Random Walk (CTRW) framework, which characterizes the interaction between the fractured and porous rock domains by using a probability distribution function of residence times. A parametric study of how CTRW parameters evolve is presented, describing transport as a function of the hydraulic conductivity ratio between fractured and porous domains.

  11. Field tracer transport experiments at the site of Canada's underground research laboratory

    International Nuclear Information System (INIS)

    Frost, L.H.; Davison, C.C.; Vandergraaf, T.T.; Scheier, N.W.; Kozak, E.T.

    1997-01-01

    To gain a better understanding of the processes affecting solute transport in fractured crystalline rock, groundwater tracer experiments are being performed within natural fracture domains and excavation damage zones at various scales at the site of AECL's Underground Research Laboratory (URL). The main objective of these experiments is to develop and demonstrate methods for characterizing the solute transport properties within fractured crystalline rock. Estimates of these properties are in turn being used in AECL's conceptual and numerical models of groundwater flow and solute transport through the geosphere surrounding a nuclear fuel waste disposal vault in plutonic rock of the Canadian Shield. (author)

  12. Preliminary modeling for solute transport in a fractured zone at the Korea underground research tunnel (KURT)

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chung Kyun; Lee, Jaek Wang; Baik, Min Hoon; Jeong, Jong Tae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-02-15

    Migration tests were performed with conservative tracers in a fractured zone that had a single fracture of about 2.5 m distance at the KURT. To interpret the migration of the tracers in the fractured rock, a solute transport model was developed. A two dimensional variable aperture channel model was adopted to describe the fractured path and hydrology, and a particle tracking method was used for solute transport. The simulation tried not only to develop a migration model of solutes for open flow environments but also to produce ideas for a better understanding of solute behaviours in indefinable fracture zones by comparing them to experimental results. The results of our simulations and experiments are described as elution and breakthrough curves, and are quantified by momentum analysis. The main retardation mechanism of nonsorbing tracers, including matrixdiffusion, was investigated.

  13. Sn approach applied to the solution of transport equation

    International Nuclear Information System (INIS)

    Lopes, J.P.

    1973-09-01

    In this work the origin of the Transport Theory is considered and the Transport Equation for the movement of the neutron in a system is established in its more general form, using the laws of nuclear physics. This equation is used as the starting point for development, under adequate assumptions, of simpler models that render the problem suitable for numerical solution. Representation of this model in different geometries is presented. The different processes of nuclear physics are introduced briefly and discussed. In addition, the boundary conditions for the different cases and a general procedure for the application of the Conservation Law are stated. The last chapter deals specifically with the S n method, its development, definitions and generalities. Computational schemes for obtaining the S n solution in spherical and cylindrical geometry, and convergence acceleration methods are also developed. (author)

  14. Predictability of solute transport in diffusion-controlled hydrogeologic regimes

    International Nuclear Information System (INIS)

    Gillham, R.W.; Cherry, J.A.

    1983-01-01

    Hydrogeologic regimes that are favourable for the subsurface management of low-level radioactive wastes must have transport properties that will limit the migration velocity of contaminants to some acceptably low value. Of equal importance, for the purpose of impact assessment and licensing, is the need to be able to predict, with a reasonable degree of certainty and over long time periods, what the migration velocity of the various contaminants of interest will be. This paper presents arguments to show that in addition to having favourable velocity characteristics, transport in saturated, diffusion-controlled hydrogeologic regimes is considerably more predictable than in the most common alternatives. The classical transport models for unsaturated, saturated-advection-controlled and saturated-diffusion-controlled environments are compared, with particular consideration being given to the difficulties associated with the characterization of the respective transport parameters. Results are presented which show that the diffusion of non-reactive solutes and solutes that react according to a constant partitioning ratio (K/sub d/) are highly predictable under laboratory conditions and that the diffusion coefficients for the reactive solutes can be determined with a reasonable degree of accuracy from independent measurements of bulk density, porosity, distribution coefficient and tortuosity. Field evidence is presented which shows that the distribution of environmental isotopes and chloride in thick clayey deposits is consistent with a diffusion-type transport process in these media. These results are particularly important in that they not only demonstrate the occurrence of diffusion-controlled hydrogeologic regimes, but they also demonstrate the predictability of the migration characteristics over very long time periods

  15. A three-dimensional neutron transport benchmark solution

    International Nuclear Information System (INIS)

    Ganapol, B.D.; Kornreich, D.E.

    1993-01-01

    For one-group neutron transport theory in one dimension, several powerful analytical techniques have been developed to solve the neutron transport equation, including Caseology, Wiener-Hopf factorization, and Fourier and Laplace transform methods. In addition, after a Fourier transform in the transverse plane and formulation of a pseudo problem, two-dimensional (2-D) and three-dimensional (3-D) problems can be solved using the techniques specifically developed for the one-dimensional (1-D) case. Numerical evaluation of the resulting expressions requiring an inversion in the transverse plane have been successful for 2-D problems but becomes exceedingly difficult in the 3-D case. In this paper, we show that by using the symmetry along the beam direction, a 2-D problem can be transformed into a 3-D problem in an infinite medium. The numerical solution to the 3-D problem is then demonstrated. Thus, a true 3-D transport benchmark solution can be obtained from a well-established numerical solution to a 2-D problem

  16. A stochastic solution of the advective transport equation with uncertainty

    International Nuclear Information System (INIS)

    Williams, M.M.R.

    1991-01-01

    A model has been developed for calculating the transport of water-borne radionuclides through layers of porous materials, such as rock or clay. The model is based upon a purely advective transport equation, in which the fluid velocity is a random variable, thereby simulating dispersion in a more realistic manner than the ad hoc introduction of a dispersivity. In addition to a random velocity field, which is an observable physical phenomenon, allowance is made for uncertainty in our knowledge of the parameters which enter the equation, e.g. the retardation coefficient. This too, is assumed to be a random variable and contributes to the stochasticity of the resulting partial differential equation of transport. The stochastic differential equation can be solved analytically and then ensemble averages taken over the associated probability distribution of velocity and retardation coefficient. A method based upon a novel form of the central limit theorem of statistics is employed to obtain tractable solutions of a system consisting of many serial legs of varying properties. One interesting conclusion is that the total flux out of a medium is significantly underestimated by using the deterministic solution with an average transit time compared with that from the stochastically averaged solution. The theory is illustrated numerically for a number of physically relevant cases. (author) 8 figs., 4 tabs., 7 refs

  17. System for sampling active solutions in transport container; Systeme de prelevements de solutions actives sur les recipients de transport

    Energy Technology Data Exchange (ETDEWEB)

    Fradin, J.

    1958-12-03

    This report presents a system aimed at sampling active solution from a specific transport container (SCRGR model) while transferring this solution with a maximum safety. The sampling principle is described (a flexible tube connected to the receiving container, with a needle at the other end which goes through a rubber membrane and enters a plunger tube). Its benefits are outlined (operator protection, reduction of contamination risk; only the rubber membrane is removed and replaced). Some manufacturing details are described concerning the membrane and the cover.

  18. Hydrophilic solute transport across the rat blood-brain barrier

    International Nuclear Information System (INIS)

    Lucchesi, K.J.

    1987-01-01

    Brain capillary permeability-surface area products (PS) of hydrophilic solutes ranging in size from 180 to 5,500 Daltons were measured in rats according to the method of Ohno, Pettigrew and Rapoport. The distribution volume of 70 KD dextran at 10 minutes after i.v. injection was also measured to determine the residual volume of blood in brain tissue at the time of sacrifice. Small test solutes were injected in pairs in order to elucidate whether their transfer into the brain proceeds by diffusion through water- or lipid-filled channels or by vesicular transport. This issue was examined in rats whose blood-brain barrier (BBB) was presumed to be intact (untreated) and in rats that received intracarotid infusions to open the BBB (isosmotic salt (ISS) and hyperosmolar arabinose). Ohno PS values of 3 H-inulin and 14 C-L-glucose in untreated rats were found to decrease as the labelling time was lengthened. This was evidence that a rapidly equilibrating compartment exists between blood and brain that renders the Ohno two-compartment model inadequate for computing true transfer rate constants. When the data were reanalyzed using a multi-compartment graphical analysis, solutes with different molecular radii were found to enter the brain at approximately equal rates. Furthermore, unidirectional transport is likely to be initiated by solute adsorption to a glycocalyx coat on the luminal surface of brain capillary endothelium. Apparently, more inulin than L-glucose was adsorbed, which may account for its slightly faster transfer across the BBB. After rats were treated with intracarotid infusions of ISS or hyperosmolar arabinose, solute PS values were significantly increased, but the ratio of PS for each of the solute pairs approached that of their free-diffusion coefficients

  19. High current beam transport experiments at GSI

    International Nuclear Information System (INIS)

    Klabunde, J.; Schonlein, A.; Spadtke, P.

    1985-01-01

    The status of the high current ion beam transport experiment is reported. 190 keV Ar 1+ ions were injected into six periods of a magnetic quadrupole channel. Since the pulse length is > 0.5 ms partial space charge neutralization occurs. In our experiments, the behavior of unneutralized and partially space charge compensated beams is compared. With an unneutralized beam, emittance growth has been measured for high intensities even in case of the zero-current phase advance sigma 0 0 . This initial emittance growth at high tune depression we attribute to the homogenization effect of the space charge density. An analytical formula based on this assumption describes the emittance growth very well. Furthermore the predicted envelope instabilities for sigma 0 > 90 0 were observed even after 6 periods. In agreement with the theory, unstable beam transport was also experimentally found if a beam with different emittances in the two transverse phase planes was injected into the transport channel. Although the space charge force is reduced for a partially neutralized beam a deterioration of the beam quality was measured in a certain range of beam parameters. Only in the range where an unneutralized beam shows the initial emittance growth, the partial neutralization reduces this effect, otherwise the partially neutralized beam is more unstable

  20. Influence of pore structure on solute transport in degraded and undegraded fen peat soils

    Directory of Open Access Journals (Sweden)

    C. Kleimeier

    2017-10-01

    Full Text Available In peat soils, decomposition and degradation reduce the proportion of large pores by breaking down plant debris into smaller fragments and infilling inter-particle pore spaces. This affects water flow and solute migration which, in turn, influence reactive transport processes and biogeochemical functions. In this study we conducted flow-through reactor experiments to investigate the interplay between pore structure and solute transport in samples of undegraded and degraded peat collected in Canada and Germany, respectively. The pore size distributions and transport parameters were characterised using the breakthrough curve and two-region non-equilibrium transport model analyses for a non-reactive solute. The results of transport characterisation showed a higher fraction of immobile pores in the degraded peat with higher diffusive exchanges of solutes between the mobile and immobile pores associated with the dual-porosity structure. The rates of steady-state potential nitrate reduction were compared with pore fractions and exchange coefficients to investigate the influence of pore structure on the rates of nitrate reduction. The results indicated that the degraded peat has potential to provide the necessary boundary conditions to support nitrate removal and serves as a favourable substrate for denitrification, due to the nature of its pore structure and its lower organic carbon content compared to undegraded peat.

  1. Efflux of drugs and solutes from brain: the interactive roles of diffusional transcapillary transport, bulk flow and capillary transporters.

    Science.gov (United States)

    Groothuis, Dennis R; Vavra, Michael W; Schlageter, Kurt E; Kang, Eric W-Y; Itskovich, Andrea C; Hertzler, Shannon; Allen, Cathleen V; Lipton, Howard L

    2007-01-01

    We examined the roles of diffusion, convection and capillary transporters in solute removal from extracellular space (ECS) of the brain. Radiolabeled solutes (eight with passive distribution and four with capillary or cell transporters) were injected into the brains of rats (n=497) and multiple-time point experiments measured the amount remaining in brain as a function of time. For passively distributed compounds, there was a relationship between lipid:water solubility and total brain efflux:diffusional efflux, which dominated when k(p), the transcapillary efflux rate constant, was >10(0) h(-1); when 10(-1)transporters. The total efflux rate constant, k(eff), was the sum of a passive component (k(p)=0.0018 h(-1)), a convective component (k(csf)=0.2 h(-1)), and a variable, concentration-dependent component (k(x)=0 to 0.45 h(-1)). Compounds with cell membrane transporters had longer clearance half times as did an oligonucleotide, which interacted with cell surface receptors. Manipulation of physiologic state (n=35) did not affect efflux, but sucrose efflux half time was longer with pentobarbital anesthesia (24 h) than with no anesthesia or ketamine-xylazine anesthesia (2 to 3 h). These results show that solute clearance from normal brain ECS may involve multiple physiologic pathways, may be affected by anesthesia, and suggests that convection-mediated efflux may be manipulated to increase or decrease drug clearance from brain.

  2. Nevada commercial spent nuclear fuel transportation experience

    International Nuclear Information System (INIS)

    1991-09-01

    The purpose of this report is to present an historic overview of commercial reactor spent nuclear fuel (SNF) shipments that have occurred in the state of Nevada, and to review the accident and incident experience for this type of shipments. Results show that between 1964 and 1990, 309 truck shipments covering approximately 40,000 miles moved through Nevada; this level of activity places Nevada tenth among the states in the number of truck shipments of SNF. For the same period, 15 rail shipments moving through the State covered approximately 6,500 miles, making Nevada 20th among the states in terms of number of rail shipments. None of these shipments had an accident or an incident associated with them. Because the data for Nevada are so limited, national data on SNF transportation and the safety of truck and rail transportation in general were also assessed

  3. Assessment of applications of transport models on regional scale solute transport

    Science.gov (United States)

    Guo, Z.; Fogg, G. E.; Henri, C.; Pauloo, R.

    2017-12-01

    Regional scale transport models are needed to support the long-term evaluation of groundwater quality and to develop management strategies aiming to prevent serious groundwater degradation. The purpose of this study is to evaluate the capacity of previously-developed upscaling approaches to accurately describe main solute transport processes including the capture of late-time tails under changing boundary conditions. Advective-dispersive contaminant transport in a 3D heterogeneous domain was simulated and used as a reference solution. Equivalent transport under homogeneous flow conditions were then evaluated applying the Multi-Rate Mass Transfer (MRMT) model. The random walk particle tracking method was used for both heterogeneous and homogeneous-MRMT scenarios under steady state and transient conditions. The results indicate that the MRMT model can capture the tails satisfactorily for plume transported with ambient steady-state flow field. However, when boundary conditions change, the mass transfer model calibrated for transport under steady-state conditions cannot accurately reproduce the tailing effect observed for the heterogeneous scenario. The deteriorating impact of transient boundary conditions on the upscaled model is more significant for regions where flow fields are dramatically affected, highlighting the poor applicability of the MRMT approach for complex field settings. Accurately simulating mass in both mobile and immobile zones is critical to represent the transport process under transient flow conditions and will be the future focus of our study.

  4. Monte Carlo methods for flux expansion solutions of transport problems

    International Nuclear Information System (INIS)

    Spanier, J.

    1999-01-01

    Adaptive Monte Carlo methods, based on the use of either correlated sampling or importance sampling, to obtain global solutions to certain transport problems have recently been described. The resulting learning algorithms are capable of achieving geometric convergence when applied to the estimation of a finite number of coefficients in a flux expansion representation of the global solution. However, because of the nonphysical nature of the random walk simulations needed to perform importance sampling, conventional transport estimators and source sampling techniques require modification to be used successfully in conjunction with such flux expansion methods. It is shown how these problems can be overcome. First, the traditional path length estimators in wide use in particle transport simulations are generalized to include rather general detector functions (which, in this application, are the individual basis functions chosen for the flus expansion). Second, it is shown how to sample from the signed probabilities that arise as source density functions in these applications, without destroying the zero variance property needed to ensure geometric convergence to zero error

  5. An Experimental Study on Solute Transport in One-Dimensional Clay Soil Columns

    Directory of Open Access Journals (Sweden)

    Muhammad Zaheer

    2017-01-01

    Full Text Available Solute transport in low-permeability media such as clay has not been studied carefully up to present, and we are often unclear what the proper governing law is for describing the transport process in such media. In this study, we composed and analyzed the breakthrough curve (BTC data and the development of leaching in one-dimensional solute transport experiments in low-permeability homogeneous and saturated media at small scale, to identify key parameters controlling the transport process. Sodium chloride (NaCl was chosen to be the tracer. A number of tracer tests were conducted to inspect the transport process under different conditions. The observed velocity-time behavior for different columns indicated the decline of soil permeability when switching from tracer introducing to tracer flushing. The modeling approaches considered were the Advection-Dispersion Equation (ADE, Two-Region Model (TRM, Continuous Time Random Walk (CTRW, and Fractional Advection-Dispersion Equation (FADE. It was found that all the models can fit the transport process very well; however, ADE and TRM were somewhat unable to characterize the transport behavior in leaching. The CTRW and FADE models were better in capturing the full evaluation of tracer-breakthrough curve and late-time tailing in leaching.

  6. Solutes transport in unsaturated double-porosity medium. Modelling by homogenization and applications

    International Nuclear Information System (INIS)

    Tran Ngoc, T.D.

    2008-07-01

    This Ph.D thesis presents the development of the solute transport models in unsaturated double-porosity medium, by using the asymptotic homogenization method. The obtained macroscopic models concern diffusion, diffusion-convection and dispersion-convection, according to the transport regime which is characterized by the non-dimensional numbers. The models consist of two coupled equations that show the local non-equilibrium of concentrations. The double-porosity transport models were numerically implemented using the code COMSOL Multiphysics (finite elements method), and compared with the solution of the same problem at the fine scale. The implementation allows solving the coupled equations in the macro- and micro-porosity domains (two-scale computations). The calculations of the dispersion tensor as a solution of the local boundary value problems, were also conducted. It was shown that the dispersivity depends on the saturation, the physical properties of the macro-porosity domain and the internal structure of the double-porosity medium. Finally, two series of experiments were performed on a physical model of double-porosity that is composed of a periodic assemblage of sintered clay spheres in Hostun sand HN38. The first experiment was a drainage experiment, which was conducted in order to validate the unsaturated flow model. The second series was a dispersion experiment in permanent unsaturated water flow condition (water content measured by gamma ray attenuation technique). A good agreement between the numerical simulations and the experimental observations allows the validation of the developed models. (author)

  7. Evaluation of axial fission gas transport in power ramping experiments

    International Nuclear Information System (INIS)

    Kinoshita, Motoyasu

    1986-01-01

    The LINUS code calculates advective and diffusional transport of fission gas towards an upper plenum through the pellet-cladding gap. The basic equations were modified for analyzing a multi-component gas mixture in the gap and also for dealing with opening and/or closing of the gap, which induces additional axial gas flow. Analysis of the Petten ramp experiment shows that helium pressurization is effective in suppressing an ascending rate of fission gas concentration. After the maximum concentration is achieved through power ramping, the gas concentration could be described by a steady state analytical solution which does not depend on the filling gas pressure. (author)

  8. A Finite-Difference Solution of Solute Transport through a Membrane Bioreactor

    Directory of Open Access Journals (Sweden)

    B. Godongwana

    2015-01-01

    Full Text Available The current paper presents a theoretical analysis of the transport of solutes through a fixed-film membrane bioreactor (MBR, immobilised with an active biocatalyst. The dimensionless convection-diffusion equation with variable coefficients was solved analytically and numerically for concentration profiles of the solutes through the MBR. The analytical solution makes use of regular perturbation and accounts for radial convective flow as well as axial diffusion of the substrate species. The Michaelis-Menten (or Monod rate equation was assumed for the sink term, and the perturbation was extended up to second-order. In the analytical solution only the first-order limit of the Michaelis-Menten equation was considered; hence the linearized equation was solved. In the numerical solution, however, this restriction was lifted. The solution of the nonlinear, elliptic, partial differential equation was based on an implicit finite-difference method (FDM. An upwind scheme was employed for numerical stability. The resulting algebraic equations were solved simultaneously using the multivariate Newton-Raphson iteration method. The solution allows for the evaluation of the effect on the concentration profiles of (i the radial and axial convective velocity, (ii the convective mass transfer rates, (iii the reaction rates, (iv the fraction retentate, and (v the aspect ratio.

  9. Engineering solutions of traffic safety problems of road transport

    Directory of Open Access Journals (Sweden)

    M. Bogdevičius

    2004-02-01

    Full Text Available The authors of this paper focus on the simulation of the motor vehicle movement (taking into consideration motor vehicle dynamics, motor vehicle hydraulic brake system influence on motor vehicle movement, interaction between its wheels with road pavements, road guardrail characteristics, interaction between motor vehicle and road guardrail on a certain road section and propose their specific solution of this problem. The presented results, illustrating the motor vehicle movement trajectories (motor vehicle braking and interaction between motor vehicle and road guardrail at various initial conditions and at various certain pavement surface of the road section under investigation and work of a motor vehicle hydraulic brake system. Taking into consideration the presented general mathematical model and computer aided test results it is possible to investigate various road transport traffic situations as well as to investigate various transport traffic safety problems.

  10. Soil properties and preferential solute transport at the field scale

    DEFF Research Database (Denmark)

    Koestel, J K; Minh, Luong Nhat; Nørgaard, Trine

    An important fraction of water flow and solute transport through soil takes place through preferential flow paths. Although this had been already observed in the nineteenth century, it had been forgotten by the scientific community until it was rediscovered during the 1970s. The awareness...... of the relevance of preferential flow was broadly re-established in the community by the early 1990s. However, since then, the notion remains widespread among soil scientists that the occurrence and strength of preferential flow cannot be predicted from measurable proxy variables such as soil properties or land...

  11. Solute carrier transporters: potential targets for digestive system neoplasms

    OpenAIRE

    Xie, Jing; Zhu, Xiao Yan; Liu, Lu Ming; Meng, Zhi Qiang

    2018-01-01

    Jing Xie,1,2 Xiao Yan Zhu,1,2 Lu Ming Liu,1,2 Zhi Qiang Meng1,2 1Department of Integrative Oncology, Fudan University Shanghai Cancer Center, 2Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, People’s Republic of China Abstract: Digestive system neoplasms are the leading causes of cancer-related death all over the world. Solute carrier (SLC) superfamily is composed of a series of transporters that are ubiquitously expressed in organs and tissues o...

  12. On the Solution of the Neutron Transport Equation

    Energy Technology Data Exchange (ETDEWEB)

    Depken, S

    1962-12-15

    The neutron transport equation has occupied the attention of many authors since Placzek, Wick and others made their first attempts to solve it, Even in the simple case of energy independent cross-sections, and disregarding the motion of the scattering nucleons, it is difficult to find a solution in an analytical form which is easily surveyable and fitted for numerical calculations. In Part I of this paper some new viewpoints will be introduced which enable the solution to be presented in its simplest possible form. Part II is devoted to an investigation of some functions introduced in Part I. In Part III the results are applied to the case of large energy lethargy, and the validity of derived formulas is discussed.

  13. Applications of stochastic models to solute transport in fractured rocks

    International Nuclear Information System (INIS)

    Gelhar, L.W.

    1987-01-01

    A stochastic theory for flow and solute transport in a single variable aperture fracture bounded by sorbing porous matrix into which solutes may diffuse, is developed using a perturbation approximation and spectral solution techniques which assume local statistical homogeneity. The theory predicts that the effective aperture of the fracture for mean solute displacement will be larger than the aperture required to calculate the large-scale flow resistance of the fracture. This ratio of apertures is a function of the variance of the logarithm of the apertures. The theory also predicts the macrodispersion coefficient for large-scale transport in the fracture. The resulting macrodispersivity is proportional to the variance of the logaperture and to its correlation scale. When variable surface sorption is included, it is found that the macrodispersivity is increased significantly, in some cases more than an order of magnitude. It is also shown that the effective retardation coefficient for the sorptively heterogeneous fracture is found by simply taking the arithmetic mean of the local surface sorption coefficient. Matrix diffusion is also shown to increase the fracture macrodispesivity at very large times. A reexamination of the results of four different field tracer tests in crystalline rock in Sweden and Canada shows aperture ratios and dispersivities that are consistent with the stochastic theory. The variance of the natural logarithm of the aperture is found to be in the range of 3 to 6 and the correlation scales for logaperture ranges from .2 to 1.2 meters. Detailed recommendations for additional field investigations at scales ranging from a few meters up to a kilometer are presented. (orig.)

  14. Ground-water solute transport modeling using a three-dimensional scaled model

    International Nuclear Information System (INIS)

    Crider, S.S.

    1987-01-01

    Scaled models are used extensively in current hydraulic research on sediment transport and solute dispersion in free surface flows (rivers, estuaries), but are neglected in current ground-water model research. Thus, an investigation was conducted to test the efficacy of a three-dimensional scaled model of solute transport in ground water. No previous results from such a model have been reported. Experiments performed on uniform scaled models indicated that some historical problems (e.g., construction and scaling difficulties; disproportionate capillary rise in model) were partly overcome by using simple model materials (sand, cement and water), by restricting model application to selective classes of problems, and by physically controlling the effect of the model capillary zone. Results from these tests were compared with mathematical models. Model scaling laws were derived for ground-water solute transport and used to build a three-dimensional scaled model of a ground-water tritium plume in a prototype aquifer on the Savannah River Plant near Aiken, South Carolina. Model results compared favorably with field data and with a numerical model. Scaled models are recommended as a useful additional tool for prediction of ground-water solute transport

  15. FUTURE MODERN RETAIL SOLUTIONS AND SHOPPER EXPERIENCE

    Directory of Open Access Journals (Sweden)

    Viorica JELEV

    2018-03-01

    As competition grows, brand manager imagination needs to work, and sales growth solutions need to focus on customer focus attention. It is a difficult task if all brands offer discounts in the malls they are in, and the announcement of differentiation is put to the attention of specialists who offer solutions for fun of any kind for the clients. The article aims to present the evolution of world trade in recent years and the various ways of diversion invented by retailers to keep customers in store chains longer time for them to buy more. The conclusion of this article will focus on the idea of future trade based on modern technology inside stores, which will lead to profound changes in customer buying behavior.

  16. Solution to the monoenergetic time-dependent neutron transport equation with a time-varying source

    International Nuclear Information System (INIS)

    Ganapol, B.D.

    1986-01-01

    Even though fundamental time-dependent neutron transport problems have existed since the inception of neutron transport theory, it has only been recently that a reliable numerical solution to one of the basic problems has been obtained. Experience in generating numerical solutions to time-dependent transport equations has indicated that the multiple collision formulation is the most versatile numerical technique for model problems. The formulation coupled with a moment reconstruction of each collided flux component has led to benchmark-quality (four- to five-digit accuracy) numerical evaluation of the neutron flux in plane infinite geometry for any degree of scattering anisotropy and for both pulsed isotropic and beam sources. As will be shown in this presentation, this solution can serve as a Green's function, thus extending the previous results to more complicated source situations. Here we will be concerned with a time-varying source at the center of an infinite medium. If accurate, such solutions have both pedagogical and practical uses as benchmarks against which other more approximate solutions designed for a wider class of problems can be compared

  17. Transport in porous media containing residual hydrocarbon. 2: Experiments

    International Nuclear Information System (INIS)

    Hatfield, K.; Ziegler, J.; Burris, D.R.

    1993-01-01

    When liquid hydrocarbons or nonaqueous-phase liquids (NAPLs) become entrapped below the water table, flowing ground waters carry soluble NAPL components away from the spill zone. Transport of these dissolved NAPL components is controlled by several processes including advection, dispersion, sorption to aquifer materials, and liquid-liquid partitioning. To better understand these processes, miscible displacement experiments were conducted to generate break-through curves (BTCs) of pentafluorobenzoic acid (PFBA), benzene, and toluene on sand column with and without a fixed decane residual. A departure from equilibrium transport is observed in BTCs from the sand-decane system. These BTCs show characteristics of early breakthrough, asymmetry, and tailing. The cause of nonequilibrium is hypothesized to be rate-limited solute exchange between decane and water. A new transport model, capable of handling time-dependent exchange processes, is successfully applied to reproduce experimental BATCs. Results indicate that time-dependent partitioning becomes increasingly important as the solute decane-water partition coefficient and the aqueous-phase fluid velocity increase

  18. Solution of charged particle transport equation by Monte-Carlo method in the BRANDZ code system

    International Nuclear Information System (INIS)

    Artamonov, S.N.; Androsenko, P.A.; Androsenko, A.A.

    1992-01-01

    Consideration is given to the issues of Monte-Carlo employment for the solution of charged particle transport equation and its implementation in the BRANDZ code system under the conditions of real 3D geometry and all the data available on radiation-to-matter interaction in multicomponent and multilayer targets. For the solution of implantation problem the results of BRANDZ data comparison with the experiments and calculations by other codes in complexes systems are presented. The results of direct nuclear pumping process simulation for laser-active media by a proton beam are also included. 4 refs.; 7 figs

  19. Solute trapping: Comparison of theory with experiment

    International Nuclear Information System (INIS)

    Aziz, M.J.; Tsao, J.Y.; Thompson, M.O.; Peercy, P.S.; White, C.W.

    1986-01-01

    The dependence of the nonequilibrium partition coefficient k of Bi in Si upon solidification velocity v has been measured with sufficient accuracy to distinguish between proposed solute-trapping mechanisms. For the range of measured velocities, 2--14 m/s, we observe a much more gradual increase in k with increasing v than those previously reported and no evidence for a ''saturation'' effect, i.e., dk/dv→0 at k<1. The continuous-growth model of Aziz fits the data quite well; the Aziz stepwise-growth model and the two-level Baker model yield values of dk/dv that are too high

  20. Mathematical model formulation and validation of water and solute transport in whole hamster pancreatic islets.

    Science.gov (United States)

    Benson, James D; Benson, Charles T; Critser, John K

    2014-08-01

    Optimization of cryopreservation protocols for cells and tissues requires accurate models of heat and mass transport. Model selection often depends on the configuration of the tissue. Here, a mathematical and conceptual model of water and solute transport for whole hamster pancreatic islets has been developed and experimentally validated incorporating fundamental biophysical data from previous studies on individual hamster islet cells while retaining whole-islet structural information. It describes coupled transport of water and solutes through the islet by three methods: intracellularly, intercellularly, and in combination. In particular we use domain decomposition techniques to couple a transmembrane flux model with an interstitial mass transfer model. The only significant undetermined variable is the cellular surface area which is in contact with the intercellularly transported solutes, Ais. The model was validated and Ais determined using a 3×3 factorial experimental design blocked for experimental day. Whole islet physical experiments were compared with model predictions at three temperatures, three perfusing solutions, and three islet size groups. A mean of 4.4 islets were compared at each of the 27 experimental conditions and found to correlate with a coefficient of determination of 0.87±0.06 (mean ± SD). Only the treatment variable of perfusing solution was found to be significant (p<0.05). We have devised a model that retains much of the intrinsic geometric configuration of the system, and thus fewer laboratory experiments are needed to determine model parameters and thus to develop new optimized cryopreservation protocols. Additionally, extensions to ovarian follicles and other concentric tissue structures may be made. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Transport of E. coli D21g with runoff water under different solution chemistry conditions and surface slopes

    Science.gov (United States)

    Tracer and indicator microbe runoff experiments were conducted to investigate the influence of solution chemistry on the transport, retention, and release of Escherichia coli D21g. Experiments were conducted in a chamber (2.25 m long, 0.15 m wide, and 0.16 m high) packed with ultrapure quartz sand (...

  2. A Review of Darcy's Law: Limitations and Alternatives for Predicting Solute Transport

    Science.gov (United States)

    Steenhuis, Tammo; Kung, K.-J. Sam; Jaynes, Dan; Helling, Charles S.; Gish, Tim; Kladivko, Eileen

    2016-04-01

    Darcy's Law that was derived originally empirically 160 years ago, has been used successfully in calculating the (Darcy) flux in porous media throughout the world. However, field and laboratory experiments have demonstrated that the Darcy flux employed in the convective disperse equation could only successfully predict solute transport under two conditions: (1) uniformly or densely packed porous media; and (2) field soils under relatively dry condition. Employing the Darcy flux for solute transport in porous media with preferential flow pathways was problematic. In this paper we examine the theoretical background behind these field and laboratory observations and then provide an alternative to predict solute movement. By examining the characteristics of the momentum conservation principles on which Darcy's law is based, we show under what conditions Darcy flux can predict solute transport in porous media of various complexity. We find that, based on several case studies with capillary pores, Darcy's Law inherently merges momentum and in that way erases information on pore-scale velocities. For that reason the Darcy flux cannot predict flow in media with preferential flow conduits where individual pore velocities are essential in predicting the shape of the breakthrough curve and especially "the early arrival" of solutes. To overcome the limitations of the assumption in Darcy's law, we use Jury's conceptualization and employ the measured chemical breakthrough curve as input to characterize the impact of individual preferential flow pathways on chemical transport. Specifically, we discuss how best to take advantage of Jury's conceptualization to extract the pore-scale flow velocity to accurately predict chemical transport through soils with preferential flow pathways.

  3. Indirect estimation of the Convective Lognormal Transfer function model parameters for describing solute transport in unsaturated and undisturbed soil.

    Science.gov (United States)

    Mohammadi, Mohammad Hossein; Vanclooster, Marnik

    2012-05-01

    Solute transport in partially saturated soils is largely affected by fluid velocity distribution and pore size distribution within the solute transport domain. Hence, it is possible to describe the solute transport process in terms of the pore size distribution of the soil, and indirectly in terms of the soil hydraulic properties. In this paper, we present a conceptual approach that allows predicting the parameters of the Convective Lognormal Transfer model from knowledge of soil moisture and the Soil Moisture Characteristic (SMC), parameterized by means of the closed-form model of Kosugi (1996). It is assumed that in partially saturated conditions, the air filled pore volume act as an inert solid phase, allowing the use of the Arya et al. (1999) pragmatic approach to estimate solute travel time statistics from the saturation degree and SMC parameters. The approach is evaluated using a set of partially saturated transport experiments as presented by Mohammadi and Vanclooster (2011). Experimental results showed that the mean solute travel time, μ(t), increases proportionally with the depth (travel distance) and decreases with flow rate. The variance of solute travel time σ²(t) first decreases with flow rate up to 0.4-0.6 Ks and subsequently increases. For all tested BTCs predicted solute transport with μ(t) estimated from the conceptual model performed much better as compared to predictions with μ(t) and σ²(t) estimated from calibration of solute transport at shallow soil depths. The use of μ(t) estimated from the conceptual model therefore increases the robustness of the CLT model in predicting solute transport in heterogeneous soils at larger depths. In view of the fact that reasonable indirect estimates of the SMC can be made from basic soil properties using pedotransfer functions, the presented approach may be useful for predicting solute transport at field or watershed scales. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Solutions to Improve Person Transport System in the Pitesti City by Analyzing Public Transport vs. Private Transport

    Science.gov (United States)

    Mihaela, Istrate; Alexandru, Boroiu; Viorel, Nicolae; Ionel, Vieru

    2017-10-01

    One of the major problems facing the Pitesti city is the road congestion that occurs in the central area of the city during the peak hours. With all the measures taken in recent years - the widening of road arteries, increasing the number of parking spaces, the creation of overground road passages - it is obvious that the problem can only be solved by a new philosophy regarding urban mobility: it is no longer possible to continue through solutions to increase the accessibility of the central area of the city, but it is necessary, on the contrary, to promote a policy of discouraging the penetration of vehicles in the city center, coupled with a policy of improving the connection between urban public transport and county public transport. This new approach is also proposed in the new Urban Mobility Plan of Pitesti city, under development. The most convincing argument for the necessity of this new orientation in the Pitesti city mobility plan is based on the analysis of the current situation of passenger transport on the territory of Pitesti city: the analysis of “public transport versus private transport” reveals a very low occupancy rate for cars and the fact that the road surface required for a passenger (the dynamic area) is much higher in the case of private transport than in the case of public transport. Measurements of passenger flows and vehicle flows on the 6 penetration ways in the city have been made and the calculations clearly demonstrate the benefits of an urban public transport system connected by “transshipment buses” to be made at the edge of the city, to the county public transport system. In terms of inter-county transport, it will continue to be connected to the urban public transport system by existing bus Station, within the city: South Bus Station and North Bus Station. The usefulness of the paper is that it identifies the solutions for sustainable mobility in Pitesti city and proposes concrete solutions for the development of the

  5. Approximate solutions for the two-dimensional integral transport equation. Solution of complex two-dimensional transport problems

    International Nuclear Information System (INIS)

    Sanchez, Richard.

    1980-11-01

    This work is divided into two parts: the first part deals with the solution of complex two-dimensional transport problems, the second one (note CEA-N-2166) treats the critically mixed methods of resolution. A set of approximate solutions for the isotropic two-dimensional neutron transport problem has been developed using the interface current formalism. The method has been applied to regular lattices of rectangular cells containing a fuel pin, cladding, and water, or homogenized structural material. The cells are divided into zones that are homogeneous. A zone-wise flux expansion is used to formulate a direct collision probability problem within a cell. The coupling of the cells is effected by making extra assumptions on the currents entering and leaving the interfaces. Two codes have been written: CALLIOPE uses a cylindrical cell model and one or three terms for the flux expansion, and NAUSICAA uses a two-dimensional flux representation and does a truly two-dimensional calculation inside each cell. In both codes, one or three terms can be used to make a space-independent expansion of the angular fluxes entering and leaving each side of the cell. The accuracies and computing times achieved with the different approximations are illustrated by numerical studies on two benchmark problems and by calculations performed in the APOLLO multigroup code [fr

  6. Interpretation of criticality experiments on homogeneous solutions of plutonium and uranium; Interpretation des experiences de criticite sur des solutions homogenes de plutonium et d'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Ithurralde, M F; Kremser, J; Leclerc, J; Lombard, Ch; Moreau, J; Robin, C [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    Criticality experiments on solutions of fissionable materials have been carried out in tanks of various geometries (cylinder, isolated annular cylinder, interacting annular cylinders); the reflexion conditions have also been varied (without reflection, semi-reflection and total reflexion by water). The range of the studied concentrations is rather large (18,8 to 104 gms/liter). The interpretation of these experiments has been undertaken in order to resolve the problems of the industrial use of homogeneous plutonium and uranium solutions. Several methods the fields of application of which are different have been used: diffusion method, transport method and Monte-Carlo method. (authors) [French] Des experiences critiques sur des solutions de matieres fissiles ont ete faites dans des cuves de diverses geometries (cylindre, cylindre annulaire isole, cylindre annulaire en interaction), les conditions de reflexion ont ete egalement variees (sans reflexion, semi reflexion et reflexion totale par l'eau). La gamme des concentrations etudiees est assez etendue (18,8 a 104 g/l ). L'interpretation de ces experiences a ete entreprise dans le but de pouvoir resoudre les problemes poses par l'emploi industriel de solutions homogenes de plutonium et d'uranium, plusieurs methodes dont les domaines d'application sont differents ont ete employees: methode de diffusion, methode de transport, methode de Monte-Carlo. (auteurs)

  7. Hyporheic less-mobile porosity and solute transport in porous media

    Science.gov (United States)

    MahmoodPoorDehkordy, F.; Briggs, M. A.; Day-Lewis, F. D.; Scruggs, C.; Singha, K.; Zarnetske, J. P.; Lane, J. W., Jr.; Bagtzoglou, A. C.

    2017-12-01

    Solute transport and reactive processes are strongly influenced by hydrodynamic exchange with the hyporheic zone. Contaminant transport and redox zonation in the hyporheic zone and near-stream aquifer can be impacted by the exchange between mobile and less-mobile porosity zones in heterogeneous porous media. Less-mobile porosity zones can be created by fine materials with tight pore throats (e.g. clay, organics) and in larger, well-connected pores down gradient of flow obstructions (e.g. sand behind cobbles). Whereas fluid sampling is primarily responsive to the more-mobile domain, tracking solute tracer dynamics by geoelectrical methods provides direct information about both more- and less-mobile zones. During tracer injection through porous media of varied pore connectivity, a lag between fluid and bulk electrical conductivity is observed, creating a hysteresis loop when plotted in conductivity space. Thus, the combination of simultaneous fluid and bulk electrical conductivity measurements enables a much improved quantification of less-mobile solute dynamics compared to traditional fluid-only sampling approaches. We have demonstrated the less-mobile porosity exchange in laboratory-scale column experiments verified by simulation models. The experimental approach has also been applied to streambed sediments in column and reach-scale field experiments and verified using numerical simulation. Properties of the resultant hysteresis loops can be used to estimate exchange parameters of less-mobile porosity. Our integrated approach combining field experiments, laboratory experiments, and numerical modeling provides new insights into the effect of less-mobile porosity on solute transport in the hyporheic zone.

  8. Transport of titanium dioxide nanoparticles in saturated porous media under various solution chemistry conditions

    International Nuclear Information System (INIS)

    Wang Yu; Gao Bin; Morales, Verónica L.; Tian Yuan; Wu Lei; Gao Jie; Bai Wei; Yang Liuyan

    2012-01-01

    Because of its wide applications, nanosized titanium dioxide may become a potential environmental risk to soil and groundwater system. It is therefore important to improve current understanding of the environmental fate and transport of titanium oxides nanoparticles (TONPs). In this work, the effect of solution chemistry (i.e., pH, ionic strength, and natural organic matter (NOM) concentration) on the deposition and transport of TONPs in saturated porous media was examined in detail. Laboratory columns packed with acid-cleaned quartz sand were used in the experiment as porous media. Transport experiments were conducted with various chemistry combinations, including four ionic strengths, three pH levels, and two NOM concentrations. The results showed that TONP mobility increased with increasing solution pH, but decreased with increasing solution ionic strength. It is also found that the presence of NOM in the system enhanced the mobility of TONPs in the saturated porous media. The Derjaguin–Landau–Verwey–Overbeek (DLVO) theory was used to justify the mobility trends observed in the experimental data. Predictions from the theory agreed excellently with the experimental data.

  9. Finite element simulation of moisture movement and solute transport in a large caisson

    International Nuclear Information System (INIS)

    Huyakorn, P.S.; Jones, B.G.; Parker, J.C.; Wadsworth, T.D.; White, H.O. Jr.

    1987-01-01

    The results of the solute transport experiments performed on compacted, crushed Bandelier Tuff in caisson B of the experimental cluster described by DePoorter (1981) are simulated. Both one- and three-dimensional simulations of solute transport have been performed using two selected finite element codes. Results of bromide and iodide tracer experiments conducted during near-steady flow conditions have been analyzed for pulse additions made on December 6, 1984, and followed over a period of up to 60 days. In addition, a pulse addition of nonconservative strontium tracer on September 28, 1984, during questionably steady flow conditions has been analyzed over a period of 240 days. One-dimensional finite element flow and transport simulations were carried out assuming the porous medium to be homogeneous and the injection source uniformly distributed. To evaluate effects of the nonuniform source distribution and also to investigate effects of inhomogeneous porous medium properties, three dimensional finite element analyses of transport were carried out. Implications of the three-dimensional effects for the design and analysis of future tracer studies are discussed

  10. Multigroup adjoint transport solution using the method of cyclic characteristics

    International Nuclear Information System (INIS)

    Assawaroongruengchot, M.; Marleau, G.

    2005-01-01

    The adjoint transport solution algorithm based on the method of cyclic characteristics (MOCC) is developed for the heterogeneous 2-dimensional geometries. The adjoint characteristics equation associated with a cyclic tracking line is formulated, then a closed form for adjoint angular flux can be determined. The acceleration techniques are implemented using the group-reduction and group-splitting techniques. To demonstrate the efficacy of the algorithm, the calculations are performed on the 17*17 PWR and Watanabe-Maynard benchmark problems. Comparisons of adjoint flux and k eff results obtained by MOCC and collision probability (CP) methods are performed. The mathematical relationship between pseudo-adjoint flux obtained by CP method and adjoint flux by MOCC method is presented. It appears that the pseudo-adjoint flux by CP method is equivalent to the adjoint flux by MOCC method and that the MOCC method requires lower computing time than the CP method for a single adjoint flux calculation

  11. Multigroup adjoint transport solution using the method of cyclic characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Assawaroongruengchot, M.; Marleau, G. [Ecole Polytechnique de Montreal, Institut de Genie Nucleaire, Montreal, Quebec (Canada)

    2005-07-01

    The adjoint transport solution algorithm based on the method of cyclic characteristics (MOCC) is developed for the heterogeneous 2-dimensional geometries. The adjoint characteristics equation associated with a cyclic tracking line is formulated, then a closed form for adjoint angular flux can be determined. The acceleration techniques are implemented using the group-reduction and group-splitting techniques. To demonstrate the efficacy of the algorithm, the calculations are performed on the 17*17 PWR and Watanabe-Maynard benchmark problems. Comparisons of adjoint flux and k{sub eff} results obtained by MOCC and collision probability (CP) methods are performed. The mathematical relationship between pseudo-adjoint flux obtained by CP method and adjoint flux by MOCC method is presented. It appears that the pseudo-adjoint flux by CP method is equivalent to the adjoint flux by MOCC method and that the MOCC method requires lower computing time than the CP method for a single adjoint flux calculation.

  12. The quasi-diffusive approximation in transport theory: Local solutions

    International Nuclear Information System (INIS)

    Celaschi, M.; Montagnini, B.

    1995-01-01

    The one velocity, plane geometry integral neutron transport equation is transformed into a system of two equations, one of them being the equation of continuity and the other a generalized Fick's law, in which the usual diffusion coefficient is replaced by a self-adjoint integral operator. As the kernel of this operator is very close to the Green function of a diffusion equation, an approximate inversion by means of a second order differential operator allows to transform these equations into a purely differential system which is shown to be equivalent, in the simplest case, to a diffusion-like equation. The method, the principles of which have been exposed in a previous paper, is here extended and applied to a variety of problems. If the inversion is properly performed, the quasi-diffusive solutions turn out to be quite accurate, even in the vicinity of the interface between different material regions, where elementary diffusion theory usually fails. 16 refs., 3 tabs

  13. Approximate solution to neutron transport equation with linear anisotropic scattering

    International Nuclear Information System (INIS)

    Coppa, G.; Ravetto, P.; Sumini, M.

    1983-01-01

    A method to obtain an approximate solution to the transport equation, when both sources and collisions show a linearly anisotropic behavior, is outlined and the possible implications for numerical calculations in applied neutronics as well as shielding evaluations are investigated. The form of the differential system of equations taken by the method is quite handy and looks simpler and more manageable than any other today available technique. To go deeper into the efficiency of the method, some typical calculations concerning critical dimension of multiplying systems are then performed and the results are compared with the ones coming from the classical Ssub(N) approximations. The outcome of such calculations leads us to think of interesting developments of the method which could be quite useful in alternative to other today widespread approximate procedures, for any geometry, but especially for curved ones. (author)

  14. Engineering charge transport by heterostructuring solution-processed semiconductors

    Science.gov (United States)

    Voznyy, Oleksandr; Sutherland, Brandon R.; Ip, Alexander H.; Zhitomirsky, David; Sargent, Edward H.

    2017-06-01

    Solution-processed semiconductor devices are increasingly exploiting heterostructuring — an approach in which two or more materials with different energy landscapes are integrated into a composite system. Heterostructured materials offer an additional degree of freedom to control charge transport and recombination for more efficient optoelectronic devices. By exploiting energetic asymmetry, rationally engineered heterostructured materials can overcome weaknesses, augment strengths and introduce emergent physical phenomena that are otherwise inaccessible to single-material systems. These systems see benefit and application in two distinct branches of charge-carrier manipulation. First, they influence the balance between excitons and free charges to enhance electron extraction in solar cells and photodetectors. Second, they promote radiative recombination by spatially confining electrons and holes, which increases the quantum efficiency of light-emitting diodes. In this Review, we discuss advances in the design and composition of heterostructured materials, consider their implementation in semiconductor devices and examine unexplored paths for future advancement in the field.

  15. Coupling of solute transport and cell expansion in pea stems

    Science.gov (United States)

    Schmalstig, J. G.; Cosgrove, D. J.

    1990-01-01

    As cells expand and are displaced through the elongation zone of the epicotyl of etiolated pea (Pisum sativum L. var Alaska) seedlings, there is little net dilution of the cell sap, implying a coordination between cell expansion and solute uptake from the phloem. Using [14C] sucrose as a phloem tracer (applied to the hypogeous cotyledons), the pattern of label accumulation along the stem closely matched the growth rate pattern: high accumulation in the growing zone, little accumulation in nongrowing regions. Several results suggest that a major portion of phloem contents enters elongating cells through the symplast. We propose that the coordination between phloem transport and cell expansion is accomplished via regulatory pathways affecting both plasmodesmata conductivity and cell expansion.

  16. Study of reactive solutes transport and PAH migration in unsaturated soils

    International Nuclear Information System (INIS)

    Gujisaite, V.; Simonnot, M.O.; Gujisaite, V.; Morel, J.L.; Ouvrard, S.; Simonnot, M.O.; Gaudet, J.P.

    2005-01-01

    Experimental studies about solute transport in soil have most of the time been conducted under saturated conditions, whereas studies with unsaturated media are usually limited to hydrodynamic analysis. Those are mainly concerning the prediction of water flow, which is the main vector for the transport of contaminants in soil. Only a few studies have made the link between unsaturated flow and physical, chemical and biological interactions, which are controlling the availability of pollutants. However, the presence of a gaseous phase in soil can modify not only the movement of soil solution, but also chemical interactions and exchanges between soil aggregates and solution. Study of reactive solute transport in the vadose zone seems thus to be a necessary stage to predict contaminant fate in natural soils, for risk assessment as well as for the design of effective processes for the remediation of contaminated soils. This question is the main objective of the present work developed in the frame of our French Scientific Interest Group Industrial Wastelands called 'GISFI' (www.gisfi.prd.fr), based around a scientific and technological project dedicated to acquisition of knowledge for sustainable requalification of degraded sites polluted by past industrial activities. We will focus here on Polycyclic Aromatic Hydrocarbons (PAH), which are among the most widely discussed environmental contaminants because of their toxicity for human health and ecosystems. They are present in large quantities in soils polluted by former industrial activities, especially in relation to the coal extraction, exploitation and treatment. An experimental system has been specifically designed at the laboratory scale to carry out experiments under controlled conditions, with an unsaturated steady-state flow. The first experiments are performed on model soils, in order to investigate unsaturated steady-state flow in relation to interactions mechanisms. We have thus chosen to use a sandy

  17. Ben Macdhui High Altitude Trace Gas and Aerosol Transport Experiment

    CSIR Research Space (South Africa)

    Piketh, SJ

    1999-01-01

    Full Text Available The Ben Macdhui High Altitude Aerosol and Trace Gas Transport Experiment (BHATTEX) was started to characterize the nature and magnitude of atmospheric, aerosol and trace gas transport paths recirculation over and exiting from southern Africa...

  18. Fluid and solute transport in a network of channels

    International Nuclear Information System (INIS)

    Moreno, L.; Neretnieks, I.

    1991-09-01

    A three-dimensional channel network model is presented. The fluid flow and solute transport are assumed to take place through a network of connected channels. The channels are generated assuming that the conductances are lognormally distributed. The flow is calculated resolving the pressure distribution and the sole transport is calculated by using a particle tracking technique. The model includes diffusion into the rock matrix and sorption within the matrix in addition to advection along the channel network. Different approaches are used to describe the channel volume and its relation to the conductivity. To quantify the diffusion into the rock matrix the size of the flow wetted surface (contact surface between the channel and the rock) is needed in addition to the diffusion properties and the sorption capacity of the rock. Two different geometries were simulated: regional parallel flow and convergent flow toward a tunnel. In the generation of the channel network, it is found that its connectivity is reduced when the standard deviation in conductances is increased. For large standard deviations, the water conducting channels are found to be few. Standard deviations for the distribution of the effluent channel flowrates were calculated. Comparisons were made with experimental data from drifts and tunnels as well as boreholes as a means to validate the model. (au) (31 refs.)

  19. Air medical transportation in India: Our experience

    Directory of Open Access Journals (Sweden)

    Himanshu Khurana

    2016-01-01

    Conclusion: Cardiac and central nervous system ailments are the most common indication for air medical transportation. These patients may need attention and interventions as any critical patient in the hospital but in a difficult environment lacking space and help. Air medical transport carries no more risk than ground transportation.

  20. Improved parallel solution techniques for the integral transport matrix method

    Energy Technology Data Exchange (ETDEWEB)

    Zerr, R. Joseph, E-mail: rjz116@psu.edu [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA (United States); Azmy, Yousry Y., E-mail: yyazmy@ncsu.edu [Department of Nuclear Engineering, North Carolina State University, Burlington Engineering Laboratories, Raleigh, NC (United States)

    2011-07-01

    Alternative solution strategies to the parallel block Jacobi (PBJ) method for the solution of the global problem with the integral transport matrix method operators have been designed and tested. The most straightforward improvement to the Jacobi iterative method is the Gauss-Seidel alternative. The parallel red-black Gauss-Seidel (PGS) algorithm can improve on the number of iterations and reduce work per iteration by applying an alternating red-black color-set to the subdomains and assigning multiple sub-domains per processor. A parallel GMRES(m) method was implemented as an alternative to stationary iterations. Computational results show that the PGS method can improve on the PBJ method execution time by up to 10´ when eight sub-domains per processor are used. However, compared to traditional source iterations with diffusion synthetic acceleration, it is still approximately an order of magnitude slower. The best-performing cases are optically thick because sub-domains decouple, yielding faster convergence. Further tests revealed that 64 sub-domains per processor was the best performing level of sub-domain division. An acceleration technique that improves the convergence rate would greatly improve the ITMM. The GMRES(m) method with a diagonal block pre conditioner consumes approximately the same time as the PBJ solver but could be improved by an as yet undeveloped, more efficient pre conditioner. (author)

  1. Improved parallel solution techniques for the integral transport matrix method

    International Nuclear Information System (INIS)

    Zerr, R. Joseph; Azmy, Yousry Y.

    2011-01-01

    Alternative solution strategies to the parallel block Jacobi (PBJ) method for the solution of the global problem with the integral transport matrix method operators have been designed and tested. The most straightforward improvement to the Jacobi iterative method is the Gauss-Seidel alternative. The parallel red-black Gauss-Seidel (PGS) algorithm can improve on the number of iterations and reduce work per iteration by applying an alternating red-black color-set to the subdomains and assigning multiple sub-domains per processor. A parallel GMRES(m) method was implemented as an alternative to stationary iterations. Computational results show that the PGS method can improve on the PBJ method execution time by up to 10´ when eight sub-domains per processor are used. However, compared to traditional source iterations with diffusion synthetic acceleration, it is still approximately an order of magnitude slower. The best-performing cases are optically thick because sub-domains decouple, yielding faster convergence. Further tests revealed that 64 sub-domains per processor was the best performing level of sub-domain division. An acceleration technique that improves the convergence rate would greatly improve the ITMM. The GMRES(m) method with a diagonal block pre conditioner consumes approximately the same time as the PBJ solver but could be improved by an as yet undeveloped, more efficient pre conditioner. (author)

  2. A study on the adsorption and subsurface transport of radioactive solutes in the presence of chelating agents

    International Nuclear Information System (INIS)

    Baik, Min Hoon

    1994-02-01

    In this study, adsorption and transport models were developed to analyze the effect of chelating agents on the adsorption and subsurface transport of radioactive solutes. The effect of chelating agents on the adsorption of radioactive solutes was analyzed by developing an adsorption model based upon the extended concept of distribution coefficient reflecting the presence of chelating agents. Also, a batch adsorption experiment was conducted in order to validate the developed adsorption model and to investigate the effect of chelating agent on the adsorption of radioactive metal solutes. In this experiment, a Cobalt(II)/EDTA/Bentonite system was considered as a representative chelation/adsorption system. It was found from the results that the presence of chelating agents significantly reduced the adsorbing capacity of geologic media such as clay minerals and soils. Thus it was concluded that the presence of chelating agents even in a small amount could contribute to the mobilization of radioactive solutes from radioactive waste burial sites by reducing the adsorbing capacity of geologic media. The effect of chelating agents on the transport of radioactive solutes in subsurface porous media was analyzed by formulating an advective-dispersive transport model which incorporated chelate formation, adsorption, decay, and degradations and by introducing the concept of a tenad. Particularly the governing equation for the tenad of radioactive solutes, M, was presented as a linear partial differential form by introducing the extended distribution coefficient, K D . The calculated results from the model showed that the transport rate of the chelated radionuclides was much greater than that of the free ionic radionuclides. This much faster transport of the chelated radionuclides was found to be due to the lower retardation factor of the chelated radionuclides than the free ionic radionuclides. The effect of parameters on the transport of radioactive solutes was also analyzed

  3. Solution processed metal oxide thin film hole transport layers for high performance organic solar cells

    Science.gov (United States)

    Steirer, K. Xerxes; Berry, Joseph J.; Chesin, Jordan P.; Lloyd, Matthew T.; Widjonarko, Nicodemus Edwin; Miedaner, Alexander; Curtis, Calvin J.; Ginley, David S.; Olson, Dana C.

    2017-01-10

    A method for the application of solution processed metal oxide hole transport layers in organic photovoltaic devices and related organic electronics devices is disclosed. The metal oxide may be derived from a metal-organic precursor enabling solution processing of an amorphous, p-type metal oxide. An organic photovoltaic device having solution processed, metal oxide, thin-film hole transport layer.

  4. Transport of oxide spent fuel. Industrial experience of COGEMA

    International Nuclear Information System (INIS)

    Lenail, B.

    1985-01-01

    COGEMA, the world leading Company in the reprocessing industry who is also involved in the transport activity, is ruling all transports of spent fuel to La Hague reprocessing plant. The paper summarizes some aspects of the experience gained in this field (road, rail and sea transports) and describes the standards defined by COGEMA as regards transport casks. These standards are as follows: - casks of dry type, - casks of the maximum size compatible with rail transports, - capability to be unloaded with standardized equipment and following standard procedures. Considering: 1) the extremely large experience of COGEMA for all transport modes and, 2) the fact that all these transports are performed in full compliance with the IAEA recommendations, COGEMA is convinced that its experience could serve to help countries or utilities willing to undertake to establish a transport system within their own country COGEMA is prepared to contribute to this task on terms to be agreed [fr

  5. Approximate and analytical solutions for solute transport from an injection well into a single fracture

    International Nuclear Information System (INIS)

    Chen, C.S.; Yates, S.R.

    1989-01-01

    In dealing with problems related to land-based nuclear waste management, a number of analytical and approximate solutions were developed to quantify radionuclide transport through fractures contained in the porous formation. It has been reported that by treating the radioactive decay constant as the appropriate first-order rate constant, these solutions can also be used to study injection problems of a similar nature subject to first-order chemical or biological reactions. The fracture is idealized by a pair of parallel, smooth plates separated by an aperture of constant thickness. Groundwater was assumed to be immobile in the underlying and overlying porous formations due to their low permeabilities. However, the injected radionuclides were able to move from the fracture into the porous matrix by molecular diffusion (the matrix diffusion) due to possible concentration gradients across the interface between the fracture and the porous matrix. Calculation of the transient solutions is not straightforward, and the paper documents a contained Fortran program, which computes the Stehfest inversion, the Airy functions, and gives the concentration distributions in the fracture as well as in the porous matrix for both transient and steady-state cases

  6. Hydro-dynamic Solute Transport under Two-Phase Flow Conditions.

    Science.gov (United States)

    Karadimitriou, Nikolaos K; Joekar-Niasar, Vahid; Brizuela, Omar Godinez

    2017-07-26

    There are abundant examples of natural, engineering and industrial applications, in which "solute transport" and "mixing" in porous media occur under multiphase flow conditions. Current state-of-the-art understanding and modelling of such processes are established based on flawed and non-representative models. Moreover, there is no direct experimental result to show the true hydrodynamics of transport and mixing under multiphase flow conditions while the saturation topology is being kept constant for a number of flow rates. With the use of a custom-made microscope, and under well-controlled flow boundary conditions, we visualized directly the transport of a tracer in a Reservoir-on-Chip (RoC) micromodel filled with two immiscible fluids. This study provides novel insights into the saturation-dependency of transport and mixing in porous media. To our knowledge, this is the first reported pore-scale experiment in which the saturation topology, relative permeability, and tortuosity were kept constant and transport was studied under different dynamic conditions in a wide range of saturation. The critical role of two-phase hydrodynamic properties on non-Fickian transport and saturation-dependency of dispersion are discussed, which highlight the major flaws in parametrization of existing models.

  7. European experience with spent fuel transport

    International Nuclear Information System (INIS)

    Hunter, I.A.

    1995-01-01

    Nuclear Transport Ltd has transported 5000 tonnes of spent fuel from 35 reactors in 8 European countries since 1972. Transport management is governed by the Quality Plan for: transport administration, packaging and shipment procedures at the shipping plant, operations at the power plant, and packaging and shipment organization at the power plant. Selection of a suitable carrier device is made with regard to the shipping plant requirements, physical limitations of the reactor, fuel characteristics, and transport route constraints. The transport plan is set up taking into account exploitation of the casks, reactor shut-down requirements, fuel acceptance plans at the reprocessing plant, and cask maintenance periods. A transport cycle involving spent fuel shipment to La Hague or to Sellafield takes typically two or four weeks, respectively. Most transports through Europe are by rail. A special-design railway ferry boat serves transports to the United Kingdom. Both wet or dry casks are employed. Modern casks are designed for high burnups and for oxide fuels. (J.B.)

  8. Bayesian estimation of the hydraulic and solute transport properties of a small-scale unsaturated soil column

    Directory of Open Access Journals (Sweden)

    Moreira Paulo H. S.

    2016-03-01

    Full Text Available In this study the hydraulic and solute transport properties of an unsaturated soil were estimated simultaneously from a relatively simple small-scale laboratory column infiltration/outflow experiment. As governing equations we used the Richards equation for variably saturated flow and a physical non-equilibrium dual-porosity type formulation for solute transport. A Bayesian parameter estimation approach was used in which the unknown parameters were estimated with the Markov Chain Monte Carlo (MCMC method through implementation of the Metropolis-Hastings algorithm. Sensitivity coefficients were examined in order to determine the most meaningful measurements for identifying the unknown hydraulic and transport parameters. Results obtained using the measured pressure head and solute concentration data collected during the unsaturated soil column experiment revealed the robustness of the proposed approach.

  9. Product Lifecycle Management and the Quest for Sustainable Space Transportation Solutions

    Science.gov (United States)

    Caruso, Pamela W.

    2009-01-01

    This viewgraph presentation reviews NASA Marshall's effort to sustain space transportation solutions through product lines that include: 1) Propulsion and Transportation Systems; 2) Life Support Systems; and 3) and Earth and Space Science Spacecraft Systems, and Operations.

  10. Solute transport in aquifers: The comeback of the advection dispersion equation and the First Order Approximation

    Science.gov (United States)

    Fiori, A.; Zarlenga, A.; Jankovic, I.; Dagan, G.

    2017-12-01

    Natural gradient steady flow of mean velocity U takes place in heterogeneous aquifers of random logconductivity Y = lnK , characterized by the normal univariate PDF f(Y) and autocorrelation ρY, of variance σY2 and horizontal integral scale I. Solute transport is quantified by the Breakthrough Curve (BTC) M at planes at distance x from the injection plane. The study builds on the extensive 3D numerical simulations of flow and transport of Jankovic et al. (2017) for different conductivity structures. The present study further explores the predictive capabilities of the Advection Dispersion Equation (ADE), with macrodispersivity αL given by the First Order Approximation (FOA), by checking in a quantitative manner its applicability. After a discussion on the suitable boundary conditions for ADE, we find that the ADE-FOA solution is a sufficiently accurate predictor for applications, the many other sources of uncertainty prevailing in practice notwithstanding. We checked by least squares and by comparison of travel time of quantiles of M that indeed the analytical Inverse Gaussian M with αL =σY2 I , is able to fit well the bulk of the simulated BTCs. It tends to underestimate the late arrival time of the thin and persistent tail. The tail is better reproduced by the semi-analytical MIMSCA model, which also allows for a physical explanation of the success of the Inverse Gaussian solution. Examination of the pertinent longitudinal mass distribution shows that it is different from the commonly used Gaussian one in the analysis of field experiments, and it captures the main features of the plume measurements of the MADE experiment. The results strengthen the confidence in the applicability of the ADE and the FOA to predicting longitudinal spreading in solute transport through heterogeneous aquifers of stationary random structure.

  11. Finite element based composite solution for neutron transport problems

    International Nuclear Information System (INIS)

    Mirza, A.N.; Mirza, N.M.

    1995-01-01

    A finite element treatment for solving neutron transport problems is presented. The employs region-wise discontinuous finite elements for the spatial representation of the neutron angular flux, while spherical harmonics are used for directional dependence. Composite solutions has been obtained by using different orders of angular approximations in different parts of a system. The method has been successfully implemented for one dimensional slab and two dimensional rectangular geometry problems. An overall reduction in the number of nodal coefficients (more than 60% in some cases as compared to conventional schemes) has been achieved without loss of accuracy with better utilization of computational resources. The method also provides an efficient way of handling physically difficult situations such as treatment of voids in duct problems and sharply changing angular flux. It is observed that a great wealth of information about the spatial and directional dependence of the angular flux is obtained much more quickly as compared to Monte Carlo method, where most of the information in restricted to the locality of immediate interest. (author)

  12. New constructive solutions for building of transport construction facilities

    Directory of Open Access Journals (Sweden)

    Babayev Vladimir

    2017-01-01

    Full Text Available New structural systems for civil and transport engineering were examined. The basis for the formation of the proposed reinforced concrete structures is the ideology of reducing its dead weight, with a given bearing capacity, the realization of which is accomplished by burial during concreting large-sized liners of a given shape and manufactured from lightweight, inexpensive composite materials. The process of erecting these systems is presented in two forms: for flat structures - using self-tightening concrete, and for curvilinear ones - by using shotcrete technologies. The second direction is presented by steel-reinforced concrete structures. These structural systems were created on the basis of innovative component and methods of rationalization of parameters. The basis of the above methods is a compiler which includes the finite element method, adaptive evolution method and special iterative procedures. Experimental verification of structural solutions and formation procedures for suggested systems was performed. Comparison between theoretical and experimental data is given. Suggested systems were implemented in a number of building companies.

  13. Control and optimization of solute transport in a thin porous tube

    KAUST Repository

    Griffiths, I. M.; Howell, P. D.; Shipley, R. J.

    2013-01-01

    differentials upon the dispersive solute behaviour are investigated. The model is used to explore the control of solute transport across the membrane walls via the membrane permeability, and a parametric expression for the permeability required to generate a

  14. Technology in rural transportation. Simple solution #6, traveler information on the internet

    Science.gov (United States)

    1997-01-01

    This application was identified as a promising rural Intelligent Transportation Systems (ITS) solution under a project sponsored by the Federal Highway Administration (FHWA) and the ENTERPRISE program. This summary describes the solution as well as o...

  15. Solute transport with periodic input point source in one-dimensional ...

    African Journals Online (AJOL)

    JOY

    groundwater flow velocity is considered proportional to multiple of temporal function and ζ th ... One-dimensional solute transport through porous media with or without .... solute free. ... the periodic concentration at source of the boundary i.e.,. 0.

  16. Semianalytical solutions of radioactive or reactive tracer transport in layered fractured media

    International Nuclear Information System (INIS)

    Moridis, G.J.; Bodvarsson, G.S.

    2001-01-01

    In this paper, semianalytical solutions are developed for the problem of transport of radioactive or reactive tracers (solutes or colloids) through a layered system of heterogeneous fractured media with misaligned fractures. The tracer transport equations in the matrix account for (a) diffusion, (b) surface diffusion (for solutes only), (c) mass transfer between the mobile and immobile water fractions, (d) linear kinetic or equilibrium physical, chemical, or combined solute sorption or colloid filtration, and (e) radioactive decay or first order chemical reactions. Any number of radioactive decay daughter products (or products of a linear, first-order reaction chain) can be tracked. The tracer-transport equations in the fractures account for the same processes, in addition to advection and hydrodynamic dispersion. Additionally, the colloid transport equations account for straining and velocity adjustments related to the colloidal size. The solutions, which are analytical in the Laplace space, are numerically inverted to provide the solution in time and can accommodate any number of fractured and/or porous layers. The solutions are verified using analytical solutions for limiting cases of solute and colloid transport through fractured and porous media. The effect of important parameters on the transport of 3 H, 237 Np and 239 Pu (and its daughters) is investigated in several test problems involving layered geological systems of varying complexity. 239 Pu colloid transport problems in multilayered systems indicate significant colloid accumulations at straining interfaces but much faster transport of the colloid than the corresponding strongly sorbing solute species

  17. Transport of oxide spent fuel. Industrial experience of COGEMA

    International Nuclear Information System (INIS)

    Lenail, B.

    1983-01-01

    COGEMA is ruling all transports of spent fuel to La Hague reprocessing plant. The paper summarizes some aspects of the experience gained in this field (road, rail and sea transports) and describes the standards defined by COGEMA as regards transport casks. These standards are as follows: - casks of dry type, - casks of the maximum size compatible with rail transports, - capability to be unloaded with standardized equipment and following standard procedures

  18. French experience in research reactor fuel transportation

    International Nuclear Information System (INIS)

    Raisonnier, Daniele

    1996-01-01

    Since 1963 Transnucleaire has safely performed a large number of national and international transports of radioactive material. Transnucleaire has also designed and supplied suitable packaging for all types of nuclear fuel cycle radioactive material from front-end and back-end products and for power or for research reactors. Transportation of spent fuel from power reactors are made on a regular and industrial basis, but this is not yet the case for the transport of spent fuel coming from research reactors. Each shipment is a permanent challenge and requires a reactive organization dealing with all the transportation issues. This presentation will explain the choices made by Transnucleaire and its associates to provide and optimize the corresponding services while remaining in full compliance with the applicable regulations and customer requirements. (author)

  19. Mathematical description of adsorption and transport of reactive solutes in soil: a review of selected literature

    International Nuclear Information System (INIS)

    Travis, C.C.

    1978-10-01

    This report reviews selected literature related to the mathematical description of the transport of reactive solutes through soil. The primary areas of the literature reviewed are (1) mathematical models in current use for description of the adsorption-desorption interaction between the soil solution and the soil matrix and (2) analytic solutions of the differential equations describing the convective-dispersive transport of reactive solutes through soil

  20. Facilitated transport of Cu with hydroxyapatite nanoparticles in saturated sand: Effects of solution ionic strength and composition

    Science.gov (United States)

    Column experiments were conducted to investigate the facilitated transport of Cu in association with hydroxyapatite nanoparticles (nHAP) in water-saturated quartz sand at different solution concentrations of NaCl (0 to 100 mM) or CaCl2 (0.1 to 1.0 mM). The experimental breakthrough curves and retent...

  1. Bayesian estimation of the hydraulic and solute transport properties of a small-scale unsaturated soil column

    NARCIS (Netherlands)

    Moreira, Paulo H S; Van Genuchten, Martinus Th; Orlande, Helcio R B; Cotta, Renato M.

    2016-01-01

    In this study the hydraulic and solute transport properties of an unsaturated soil were estimated simultaneously from a relatively simple small-scale laboratory column infiltration/outflow experiment. As governing equations we used the Richards equation for variably saturated flow and a physical

  2. Coupled effects of solution chemistry and hydrodynamics on the mobility and transport of quantum dot nanomaterials in the Vadose Zone

    Science.gov (United States)

    To investigate the coupled effects of solution chemistry and vadose zone processes on the mobility of quantum dot (QD) nanoparticles, laboratory scale transport experiments were performed. The complex coupled effects of ionic strength, size of QD aggregates, surface tension, contact angle, infiltrat...

  3. Self-pinched lithium beam transport experiments on SABRE

    International Nuclear Information System (INIS)

    Hanson, D.L.; Olson, C.L.; Poukey, J.W.; Shokir, I.; Cuneo, M.E.; Menge, P.R.; Johnston, R.R.; Welch, D.R.

    1996-01-01

    Self-pinched transport of ion beams has many advantages for ion-driven ICF applications involving high yield and energy production. The authors are currently preparing for a self-pinched lithium beam transport experiment on the SABRE accelerator. There are three transport elements that must eventually be demonstrated: (1) efficient lithium beam generation and ballistic transport to a focus at the self-pinched transport channel entrance; (2) self-pinched transport in the channel, requiring optimized injection conditions and gas breakdown; and (3) self-pinched transport of the equilibrated beam from the channel into free space, with associated aiming and stability considerations. In the present experiment, a hollow annular lithium beam from an applied-B extraction ion diode will be focused to small radius (r ≤ 2 cm) in a 60 cm long ballistic focus section containing argon gas at a pressure of a few Torr. The self-pinched transport channel will contain a low pressure background gas of 10--40 mTorr argon to allow sufficient net current to confine the beam for long distance transport. IPROP simulations are in progress to optimize the design of the ballistic and self-pinched transport sections. Progress on preparation of this lithium self-pinched transport experiment, including a discussion of transport system design, important gas breakdown issues, and diagnostics, will be presented

  4. Mass transfer in fuel cells. [electron microscopy of components, thermal decomposition of Teflon, water transport, and surface tension of KOH solutions

    Science.gov (United States)

    Walker, R. D., Jr.

    1973-01-01

    Results of experiments on electron microscopy of fuel cell components, thermal decomposition of Teflon by thermogravimetry, surface area and pore size distribution measurements, water transport in fuel cells, and surface tension of KOH solutions are described.

  5. The theory and experiment of solute migration caused by excited state absorptions

    International Nuclear Information System (INIS)

    Xiao, Jin; Ying-Lin, Song; Yu-Xiao, Wang; Min, Shui; Chang-Wei, Li; Jun-Yi, Yang; Xue-Ru, Zhang; Kun, Yang

    2010-01-01

    Nonsymmetrical transition from reverse-saturable absorption (RSA) to saturable absorption (SA) caused by excited state absorption induced mass transport of the CuPcTs dissolved in dimethyl sulfoxide is observed in an open aperture Z-scan experiment with a 21-ps laser pulse. The nonsymmetrical transition from RSA to SA is ascribed neither to saturation of excited state absorption nor to thermal induced mass transport, the so-called Soret effect. In our consideration, strong nonlinear absorption causes the rapid accumulation of the non-uniform kinetic energy of the solute molecules. The non-uniform kinetic field in turn causes the migration of the solute molecules. Additionally, an energy-gradient-induced mass transport theory is presented to interpret the experimental results, and the theoretical calculations are also taken to fit our experimental results. (classical areas of phenomenology)

  6. Unscented Kalman filter assimilation of time-lapse self-potential data for monitoring solute transport

    Science.gov (United States)

    Cui, Yi-an; Liu, Lanbo; Zhu, Xiaoxiong

    2017-08-01

    Monitoring the extent and evolution of contaminant plumes in local and regional groundwater systems from existing landfills is critical in contamination control and remediation. The self-potential survey is an efficient and economical nondestructive geophysical technique that can be used to investigate underground contaminant plumes. Based on the unscented transform, we have built a Kalman filtering cycle to conduct time-lapse data assimilation for monitoring the transport of solute based on the solute transport experiment using a bench-scale physical model. The data assimilation was formed by modeling the evolution based on the random walk model and observation correcting based on the self-potential forward. Thus, monitoring self-potential data can be inverted by the data assimilation technique. As a result, we can reconstruct the dynamic process of the contaminant plume instead of using traditional frame-to-frame static inversion, which may cause inversion artifacts. The data assimilation inversion algorithm was evaluated through noise-added synthetic time-lapse self-potential data. The result of the numerical experiment shows validity, accuracy and tolerance to the noise of the dynamic inversion. To validate the proposed algorithm, we conducted a scaled-down sandbox self-potential observation experiment to generate time-lapse data that closely mimics the real-world contaminant monitoring setup. The results of physical experiments support the idea that the data assimilation method is a potentially useful approach for characterizing the transport of contamination plumes using the unscented Kalman filter (UKF) data assimilation technique applied to field time-lapse self-potential data.

  7. Simultaneous transport of synthetic colloids and a nonsorbing solute through single saturated natural fractures

    International Nuclear Information System (INIS)

    Reimus, P.W.; Robinson, B.A.; Nuttall, H.E.; Kale, R.

    1994-01-01

    Tracer transport experiments involving colloids that showed little tendency to attach to rock surfaces and a nonsorbing solute (iodide) -were conducted in three different well-characterized natural fractures in tuff. The colloids always arrived earlier in the effluent than the iodide, which we believe is evidence of (1) hydrodynamic chromatography and/or (2) the fact that the colloids experience a smaller effective volume in the fracture because they diffuse too slowly to enter low-velocity regions (dead zones) along the rough fracture walls. The iodide also approached the inlet concentration in the effluent more slowly than the colloids, with the concentration at a given elution volume being greater at higher flow rates. By contrast, the rate of approach of the colloid concentration to the inlet concentration did not vary with flow rate. We attribute this behavior to matrix diffusion of the iodide, with the colloids being too large/nondiffusive to experience this phenomenon. Dispersion of all tracers was greatest in the fracture of widest average aperture and least in the fracture of narrowest aperture, which is consistent with Taylor dispersion theory. The tracer experiments were modeled/interpreted using a three-step approach that involved (1) estimating the aperture distribution in each fracture using surface profiling techniques, (2) predicting the flow field in the fractures using a localized parallel-plate approximation, and (3) predicting tracer transport in the fractures using particle-tracking techniques. Although considered preliminary at this time, the model results were in qualitative agreement with the experiments

  8. Hydrogeochemistry and simulated solute transport, Piceance Basin, northwestern Colorado

    Science.gov (United States)

    Robson, S.G.; Saulnier, G.J.

    1981-01-01

    Oil-shale mining activities in Piceance basin in northwestern Colorado could adversely affect the ground- and surface-water quality in the basin. This study of the hydrology and geochemistry of the area used ground-water solute-transport-modeling techniques to investigate the possible impact of the mines on water quality. Maps of the extent and structure of the aquifer were prepared and show that a saturated thickness of 2,000 feet occurs in the northeast part of the basin. Ground-water recharge in the upland areas in the east, south, and west parts of the basin moves down into deeper zones in the aquifer and laterally to the discharge areas along Piceance and Yellow Creeks. The saline zone and the unsaturated zone provide the majority of the dissolved solids found in the ground water. Precipitation, ion-exchange, and oxidation-reduction reactions are also occuring in the aquifer. Model simulations of ground-water pumpage in tracts C-a and C-b indicate that the altered direction of ground-water movement near the pumped mines will cause an improvement in ground-water quality near the mines and a degradation of water quality downgradient from the tracts. Model simulations of mine leaching in tract C-a and C-b indicate that equal rates of mine leaching in the tracts will produce much different effects on the water quality in the basin. Tract C-a, by virtue of its remote location from perennial streams, will primarily degrade the ground-water quality over a large area to the northeast of the tract. Tract C-b, by contrast, will primarily degrade the surface-water quality in Piceance Creek, with only localized effects on the ground-water quality. (USGS)

  9. Modeling study of solute transport in the unsaturated zone: Workshop proceedings

    International Nuclear Information System (INIS)

    Springer, E.P.; Fuentes, H.R.

    1987-04-01

    Issues addressed were the adequacy of the data for the various models, effectiveness of the models to represent the data, particular information provided by the models, the role of caisson experiments in providing fundamental knowledge of porous-media water flow and solute transport, and the importance of geochemistry to the transport of nonconservative tracers. These proceedings include the presentations made by each of the modelers; the summary document written by the panel; and a transcript of the discussions, both the discussions that followed individual presentations and the general discussion held on the second day. This publication completes the series on the workshop. Volume I in the series (NUREG/CR-4615, Vol. I) contains background information and the data sets provided each modeler

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

    Science.gov (United States)

    Leung, Juliana Y.; Srinivasan, Sanjay

    2016-09-01

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

  11. Peritoneal Fluid Transport rather than Peritoneal Solute Transport Associates with Dialysis Vintage and Age of Peritoneal Dialysis Patients

    Directory of Open Access Journals (Sweden)

    Jacek Waniewski

    2016-01-01

    Full Text Available During peritoneal dialysis (PD, the peritoneal membrane undergoes ageing processes that affect its function. Here we analyzed associations of patient age and dialysis vintage with parameters of peritoneal transport of fluid and solutes, directly measured and estimated based on the pore model, for individual patients. Thirty-three patients (15 females; age 60 (21–87 years; median time on PD 19 (3–100 months underwent sequential peritoneal equilibration test. Dialysis vintage and patient age did not correlate. Estimation of parameters of the two-pore model of peritoneal transport was performed. The estimated fluid transport parameters, including hydraulic permeability (LpS, fraction of ultrasmall pores (αu, osmotic conductance for glucose (OCG, and peritoneal absorption, were generally independent of solute transport parameters (diffusive mass transport parameters. Fluid transport parameters correlated whereas transport parameters for small solutes and proteins did not correlate with dialysis vintage and patient age. Although LpS and OCG were lower for older patients and those with long dialysis vintage, αu was higher. Thus, fluid transport parameters—rather than solute transport parameters—are linked to dialysis vintage and patient age and should therefore be included when monitoring processes linked to ageing of the peritoneal membrane.

  12. Peritoneal Fluid Transport rather than Peritoneal Solute Transport Associates with Dialysis Vintage and Age of Peritoneal Dialysis Patients

    Science.gov (United States)

    Waniewski, Jacek; Antosiewicz, Stefan; Baczynski, Daniel; Poleszczuk, Jan; Pietribiasi, Mauro; Lindholm, Bengt; Wankowicz, Zofia

    2016-01-01

    During peritoneal dialysis (PD), the peritoneal membrane undergoes ageing processes that affect its function. Here we analyzed associations of patient age and dialysis vintage with parameters of peritoneal transport of fluid and solutes, directly measured and estimated based on the pore model, for individual patients. Thirty-three patients (15 females; age 60 (21–87) years; median time on PD 19 (3–100) months) underwent sequential peritoneal equilibration test. Dialysis vintage and patient age did not correlate. Estimation of parameters of the two-pore model of peritoneal transport was performed. The estimated fluid transport parameters, including hydraulic permeability (LpS), fraction of ultrasmall pores (α u), osmotic conductance for glucose (OCG), and peritoneal absorption, were generally independent of solute transport parameters (diffusive mass transport parameters). Fluid transport parameters correlated whereas transport parameters for small solutes and proteins did not correlate with dialysis vintage and patient age. Although LpS and OCG were lower for older patients and those with long dialysis vintage, αu was higher. Thus, fluid transport parameters—rather than solute transport parameters—are linked to dialysis vintage and patient age and should therefore be included when monitoring processes linked to ageing of the peritoneal membrane. PMID:26989432

  13. Colloid transport in porous media: impact of hyper-saline solutions.

    Science.gov (United States)

    Magal, Einat; Weisbrod, Noam; Yechieli, Yoseph; Walker, Sharon L; Yakirevich, Alexander

    2011-05-01

    The transport of colloids suspended in natural saline solutions with a wide range of ionic strengths, up to that of Dead Sea brines (10(0.9) M) was explored. Migration of microspheres through saturated sand columns of different sizes was studied in laboratory experiments and simulated with mathematical models. Colloid transport was found to be related to the solution salinity as expected. The relative concentration of colloids at the columns outlet decreased (after 2-3 pore volumes) as the solution ionic strength increased until a critical value was reached (ionic strength > 10(-1.8) M) and then remained constant above this level of salinity. The colloids were found to be mobile even in the extremely saline brines of the Dead Sea. At such high ionic strength no energetic barrier to colloid attachment was presumed to exist and colloid deposition was expected to be a favorable process. However, even at these salinity levels, colloid attachment was not complete and the transport of ∼ 30% of the colloids through the 30-cm long columns was detected. To further explore the deposition of colloids on sand surfaces in Dead Sea brines, transport was studied using 7-cm long columns through which hundreds of pore volumes were introduced. The resulting breakthrough curves exhibited a bimodal shape whereby the relative concentration (C/C(0)) of colloids at the outlet rose to a value of 0.8, and it remained relatively constant (for the ∼ 18 pore volumes during which the colloid suspension was flushed through the column) and then the relative concentration increased to a value of one. The bimodal nature of the breakthrough suggests different rates of colloid attachment. Colloid transport processes were successfully modeled using the limited entrapment model, which assumes that the colloid attachment rate is dependent on the concentration of the attached colloids. Application of this model provided confirmation of the colloid aggregation and their accelerated attachment during

  14. Critical experiments for large scale enriched uranium solution handling

    International Nuclear Information System (INIS)

    Tanner, J.E.; Forehand, H.M.

    1985-01-01

    The authors have performed 17 critical experiments with a concentrated aqueous uranyl nitrate solution contained in an annular cylindrical tank, with annular cylindrical absorbers of stainless steel and/or polyethylene inside. k/sub eff/ calculated by KENO IV, employing 16-group Hansen-Roach cross sections, average 0.977. There is a variation of the calculational bias among the separate experiments, but it is too small to allow assigning it to specific components of the equipment. They are now performing critical experiments with a more concentrated uranyl nitrate solution in pairs of very squat cylindrical tanks with disc shaped absorbers and reflectors of carbon steel, stainless steel, nitronic-50, plain and borated polyethylene. These experiments are in support of upgrading fuel reprocessing at the Idaho Chemical Processing Plant

  15. Stochastic models of solute transport in highly heterogeneous geologic media

    Energy Technology Data Exchange (ETDEWEB)

    Semenov, V.N.; Korotkin, I.A.; Pruess, K.; Goloviznin, V.M.; Sorokovikova, O.S.

    2009-09-15

    A stochastic model of anomalous diffusion was developed in which transport occurs by random motion of Brownian particles, described by distribution functions of random displacements with heavy (power-law) tails. One variant of an effective algorithm for random function generation with a power-law asymptotic and arbitrary factor of asymmetry is proposed that is based on the Gnedenko-Levy limit theorem and makes it possible to reproduce all known Levy {alpha}-stable fractal processes. A two-dimensional stochastic random walk algorithm has been developed that approximates anomalous diffusion with streamline-dependent and space-dependent parameters. The motivation for introducing such a type of dispersion model is the observed fact that tracers in natural aquifers spread at different super-Fickian rates in different directions. For this and other important cases, stochastic random walk models are the only known way to solve the so-called multiscaling fractional order diffusion equation with space-dependent parameters. Some comparisons of model results and field experiments are presented.

  16. Reactive solute transport in streams: A surface complexation approach for trace metal sorption

    Science.gov (United States)

    Runkel, Robert L.; Kimball, Briant A.; McKnight, Diane M.; Bencala, Kenneth E.

    1999-01-01

    A model for trace metals that considers in-stream transport, metal oxide precipitation-dissolution, and pH-dependent sorption is presented. Linkage between a surface complexation submodel and the stream transport equations provides a framework for modeling sorption onto static and/or dynamic surfaces. A static surface (e.g., an iron- oxide-coated streambed) is defined as a surface with a temporally constant solid concentration. Limited contact between solutes in the water column and the static surface is considered using a pseudokinetic approach. A dynamic surface (e.g., freshly precipitated metal oxides) has a temporally variable solid concentration and is in equilibrium with the water column. Transport and deposition of solute mass sorbed to the dynamic surface is represented in the stream transport equations that include precipitate settling. The model is applied to a pH-modification experiment in an acid mine drainage stream. Dissolved copper concentrations were depressed for a 3 hour period in response to the experimentally elevated pH. After passage of the pH front, copper was desorbed, and dissolved concentrations returned to ambient levels. Copper sorption is modeled by considering sorption to aged hydrous ferric oxide (HFO) on the streambed (static surface) and freshly precipitated HFO in the water column (dynamic surface). Comparison of parameter estimates with reported values suggests that naturally formed iron oxides may be more effective in removing trace metals than synthetic oxides used in laboratory studies. The model's ability to simulate pH, metal oxide precipitation-dissolution, and pH-dependent sorption provides a means of evaluating the complex interactions between trace metal chemistry and hydrologic transport at the field scale.

  17. Development of solute transport models in YMPYRÄ framework to simulate solute migration in military shooting and training areas

    Science.gov (United States)

    Warsta, L.; Karvonen, T.

    2017-12-01

    There are currently 25 shooting and training areas in Finland managed by The Finnish Defence Forces (FDF), where military activities can cause contamination of open waters and groundwater reservoirs. In the YMPYRÄ project, a computer software framework is being developed that combines existing open environmental data and proprietary information collected by FDF with computational models to investigate current and prevent future environmental problems. A data centric philosophy is followed in the development of the system, i.e. the models are updated and extended to handle available data from different areas. The results generated by the models are summarized as easily understandable flow and risk maps that can be opened in GIS programs and used in environmental assessments by experts. Substances investigated with the system include explosives and metals such as lead, and both surface and groundwater dominated areas can be simulated. The YMPYRÄ framework is composed of a three dimensional soil and groundwater flow model, several solute transport models and an uncertainty assessment system. Solute transport models in the framework include particle based, stream tube and finite volume based approaches. The models can be used to simulate solute dissolution from source area, transport in the unsaturated layers to groundwater and finally migration in groundwater to water extraction wells and springs. The models can be used to simulate advection, dispersion, equilibrium adsorption on soil particles, solubility and dissolution from solute phase and dendritic solute decay chains. Correct numerical solutions were confirmed by comparing results to analytical 1D and 2D solutions and by comparing the numerical solutions to each other. The particle based and stream tube type solute transport models were useful as they could complement the traditional finite volume based approach which in certain circumstances produced numerical dispersion due to piecewise solution of the

  18. Demonstrations in Solute Transport Using Dyes: Part II. Modeling.

    Science.gov (United States)

    Butters, Greg; Bandaranayake, Wije

    1993-01-01

    A solution of the convection-dispersion equation is used to describe the solute breakthrough curves generated in the demonstrations in the companion paper. Estimation of the best fit model parameters (solute velocity, dispersion, and retardation) is illustrated using the method of moments for an example data set. (Author/MDH)

  19. A single continuum approximation of the solute transport in fractured porous media

    International Nuclear Information System (INIS)

    Jeong, J.T.; Lee, K.J.

    1992-01-01

    Solute transport in fractured porous media is described by the single continuum model, i.e., equivalent porous medium model. In this model, one-dimensional solute transport in the fracture and two-dimensional solute transport in the porous rock matrix is considered. The network of fractures embedded in the porous rock matrix is idealized as two orthogonally intersecting families of equally spaced, parallel fractures directed at 45 o to the regional groundwater flow direction. Governing equations are solved by the finite element method, and an upstream weighting technique is used in order to prevent the oscillation of the solution in the case of highly advection dominated transport. Breakthrough curves, similar to those of the one-dimensional solute transport problem in ordinary porous media, are obtained as a function of time according to volume or flux averaging of the concentration profile across the width of the flow region. The equivalent parameters, i.e., porosity and overall coefficient of longitudinal dispersivity, are obtained by a trial-and-error method. Analyses for the non-sorbing solute transport case show that within the range of considered parameters, and except for the region very close to the source, application of the single continuum model in the idealized fracture system is sufficient for modeling solute transport in fractured porous media. This numerical scheme is shown to be applicable to a sorbing solute and radionuclide transport. (author)

  20. 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...

  1. Solute transport by groundwater flow to wetland ecosystems : the environmental impact of human activities

    NARCIS (Netherlands)

    Schot, P.P.

    1991-01-01

    This thesis deals with solute transport by groundwater flow and the way in which solute transport is affected by human activities. This in relation to wetland ecosystems. Wetlands in the eastern part of the Vecht river plain in The Netherlands are historically renown for their great variety of

  2. Modeling solute transport in a heterogeneous unsaturated porous medium under dynamic boundary conditions on different spatial scales

    Science.gov (United States)

    Cremer, Clemens; Neuweiler, Insa; Bechtold, Michel

    2013-04-01

    Understanding transport of solutes/contaminants through unsaturated soil in the shallow subsurface is vital to assess groundwater quality, nutrient cycling or to plan remediation projects. Alternating precipitation and evaporation conditions causing upward and downward flux with differing flow paths, changes in saturation and related structural heterogeneity make the description of transport in the unsaturated zone near the soil-surface a complex problem. Preferential flow paths strongly depend, among other things, on the saturation of a medium. Recent studies (e.g. Bechtold et al., 2011) showed lateral flow and solute transport during evaporation conditions (upward flux) in vertically layered sand columns. Results revealed that during evaporation water and solute are redistributed laterally from coarse to fine media deeper in the soil, and towards zones of lowest hydraulic head near to the soil surface. These zones at the surface can be coarse or fine grained depending on saturation status and evaporation flux. However, if boundary conditions are reversed and precipitation is applied, the flow field is not reversed in the same manner, resulting in entirely different transport patterns for downward and upward flow. Therefore, considering net-flow rates alone is misleading when describing transport in the shallow unsaturated zone. In this contribution, we analyze transport of a solute in the shallow subsurface to assess effects resulting from the superposition of heterogeneous soil structures and dynamic flow conditions on various spatial scales. Two-dimensional numerical simulations of unsaturated flow and transport in heterogeneous porous media under changing boundary conditions are carried out using a finite-volume code coupled to a particle tracking algorithm to quantify solute transport and leaching rates. In order to validate numerical simulations, results are qualitatively compared to those of a physical experiment (Bechtold et al., 2011). Numerical

  3. Comparison of analytical transport and stochastic solutions for neutron slowing down in an infinite medium

    International Nuclear Information System (INIS)

    Jahshan, S.N.; Wemple, C.A.; Ganapol, B.D.

    1993-01-01

    A comparison of the numerical solutions of the transport equation describing the steady neutron slowing down in an infinite medium with constant cross sections is made with stochastic solutions obtained from tracking successive neutron histories in the same medium. The transport equation solution is obtained using a numerical Laplace transform inversion algorithm. The basis for the algorithm is an evaluation of the Bromwich integral without analytical continuation. Neither the transport nor the stochastic solution is limited in the number of scattering species allowed. The medium may contain an absorption component as well. (orig.)

  4. Affordable Freight Logistics Transport Information Management Optimisation and Asset Tracking Solution Using Smartphone GPS Capabilities

    Science.gov (United States)

    Muna, Joseph T.; Prescott, Kevin

    2011-08-01

    Traditionally, freight transport and telematics solutions that exploit the GPS capabilities of in- vehicle devices to provide innovative Location Based Services (LBS) including track and trace transport systems have been the preserve of a select cluster of transport operators and organisations with the financial resources to develop the requisite custom software and hardware on which they are deployed. The average cost of outfitting a typical transport vehicle or truck with the latest Intelligent Transport System (ITS) increases the cost of the vehicle by anything from a couple to several thousand Euros, depending on the complexity and completeness of the solution. Though this does not generally deter large fleet transport owners since they typically get Return on Investment (ROI) based on economies of scale, it presents a barrier for the smaller independent entities that constitute the majority of freight transport operators [1].The North Sea Freight Intelligent Transport Solution (NS FRITS), a project co-funded by the European Commission Interreg IVB North Sea Region Programme, aims to make acquisition of such transport solutions easier for those organisations that cannot afford the expensive, bespoke systems used by their larger competitors.The project addresses transport security threats by developing a system capable of informing major actors along the freight logistics supply chain, of changing circumstances within the region's major transport corridors and between transport modes. The project also addresses issues of freight volumes, inter-modality, congestion and eco-mobility [2].

  5. Fluid flow and convective transport of solutes within the intervertebral disc

    NARCIS (Netherlands)

    Ferguson, S.J.; Ito, K.; Nolte, L.P.

    2004-01-01

    Previous experimental and analytical studies of solute transport in the intervertebral disc have demonstrated that for small molecules diffusive transport alone fulfils the nutritional needs of disc cells. It has been often suggested that fluid flow into and within the disc may enhance the transport

  6. Water flow and solute transport in floating fen root mats

    Science.gov (United States)

    Stofberg, Sija F.; EATM van der Zee, Sjoerd

    2015-04-01

    be very similar and likely functionally related. Our experimental field data were used for modelling water flow and solute transport in floating fens, using HYDRUS 2D. Fluctuations of surface water and root mat, as well as geometry and unsaturated zone parameters can have a major influence on groundwater fluctuations and the exchange between rain and surface water and the water in the root mats. In combination with the duration of salt pulses in surface water, and sensitivity of fen plants to salinity (Stofberg et al. 2014, submitted), risks for rare plants can be anticipated.

  7. Experience of air transport of nuclear fuel material as type A package

    International Nuclear Information System (INIS)

    Kawasaki, Masashi; Kageyama, Tomio; Suzuki, Toru

    2004-01-01

    Special law on nuclear disaster countermeasures (hereafter called as to nuclear disaster countermeasures low) that is domestic law for dealing with measures for nuclear disaster, was enforced in June, 2000. Therefore, nuclear enterprise was obliged to report accidents as required by nuclear disaster countermeasures law, besides meeting the technical requirement of existent transport regulation. For overseas procurement of plutonium reference materials that are needed for material accountability, A Type package must be transported by air. Therefore, concept of air transport of nuclear fuel materials according to the nuclear disaster countermeasures law was discussed, and the manual including measures against accident in air transport was prepared for the oversea procurement. In this presentation, the concept of air transport of A Type package containing nuclear fuel materials according to the nuclear disaster countermeasures law, and the experience of a transportation of plutonium solution from France are shown. (author)

  8. Parallel computing solution of Boltzmann neutron transport equation

    International Nuclear Information System (INIS)

    Ansah-Narh, T.

    2010-01-01

    The focus of the research was on developing parallel computing algorithm for solving Eigen-values of the Boltzmam Neutron Transport Equation (BNTE) in a slab geometry using multi-grid approach. In response to the problem of slow execution of serial computing when solving large problems, such as BNTE, the study was focused on the design of parallel computing systems which was an evolution of serial computing that used multiple processing elements simultaneously to solve complex physical and mathematical problems. Finite element method (FEM) was used for the spatial discretization scheme, while angular discretization was accomplished by expanding the angular dependence in terms of Legendre polynomials. The eigenvalues representing the multiplication factors in the BNTE were determined by the power method. MATLAB Compiler Version 4.1 (R2009a) was used to compile the MATLAB codes of BNTE. The implemented parallel algorithms were enabled with matlabpool, a Parallel Computing Toolbox function. The option UseParallel was set to 'always' and the default value of the option was 'never'. When those conditions held, the solvers computed estimated gradients in parallel. The parallel computing system was used to handle all the bottlenecks in the matrix generated from the finite element scheme and each domain of the power method generated. The parallel algorithm was implemented on a Symmetric Multi Processor (SMP) cluster machine, which had Intel 32 bit quad-core x 86 processors. Convergence rates and timings for the algorithm on the SMP cluster machine were obtained. Numerical experiments indicated the designed parallel algorithm could reach perfect speedup and had good stability and scalability. (au)

  9. Critical experiments on low enriched uranyl nitrate solution with STACY

    International Nuclear Information System (INIS)

    Miyoshi, Yoshinori

    1996-01-01

    As the STACY started steady operations, systematic criticality data on low enriched uranyl nitrate solution system could be accumulated. Main experimental parameters for the cylindrical tank of 60 cm in diameter were uranium concentration and the reflector condition. Basic data on a simple geometry will be helpful for the validation of the standard criticality safety codes, and for evaluating the safety margin included in the criticality designs. Experiments on the reactivity effects of structural materials such as borated concrete and polyethylene are on schedule next year as the second series of experiments using 10 wt% enriched uranyl solution. Furthermore, neutron interacting experiments with two slab tanks will be performed to investigate the fundamental properties of neutron interaction effects between core tanks. These data will be useful for making more reasonable calculation models and for evaluating the safety margin in the criticality designs for the multiple unit system. (J.P.N.)

  10. Reactive transport modeling of the ABM experiment with Comsol Multiphysics

    International Nuclear Information System (INIS)

    Pekala, Marek; Idiart, Andres; Arcos, David

    2012-01-01

    Document available in extended abstract form only. The Swedish Organisation for Radioactive Waste Disposal (SKB) is considering disposal of the High Level Waste in a deep underground repository in a crystalline rock. According to the disposal concept, bentonite clay will be used in the near-field of the waste packages as buffer material. From solute transport point of view, the bentonite buffer is expected to provide a favourable environment, where radionuclide migration would be limited to slow diffusion and further retarded by sorption. In the KBS-3 repository design, the MX-80 bentonite is the reference buffer material. However, SKB has also been investigating alternative buffer materials. To this end, the field experiment Alternative Buffer Materials (ABM) was started at the Aespoe URL in 2006. Three packages of eleven different compacted bentonite blocks in different configurations have been tested over varying time scales. The packages with outer diameter of 0.28 m were deposited into 3 meter deep boreholes. After installation, packages were saturated and heated differently to target values. This contribution concerns the evolution of Package 1, which was initiated in December 2006 and ran for about 2.5 years. Post-mortem examination after retrieval showed that the initially contrasting chloride concentrations and cation-exchanger compositions between different bentonite blocks became significantly homogenised. It is thought that this behaviour could be explained as a first approximation by diffusion of major ions between the bentonite blocks coupled with cation-exchange. In this work, a modelling study to verify this hypothesis has been undertaken. In addition, the feasibility of implementing a reactive transport model into the Finite Element code COMSOL Multiphysics has been tested. The model considers a two-dimensional axisymmetric geometry of the depositional borehole, and includes coupled diffusion and cation-exchange of Na, K, Ca and Mg (as a chloride

  11. New diffusion-like solutions of one-speed transport equations in spherical geometry

    International Nuclear Information System (INIS)

    Sahni, D.C.

    1988-01-01

    Stationary, one-speed, spherically symmetric transport equations are considered in a conservative medium. Closed-form expressions are obtained for the angular flux ψ(r, μ) that yield a total flux varying as 1/r by using Sonine transforms. Properties of this solution are studied and it is shown that the solution can not be identified as a diffusion mode solution of the transport equation. Limitations of the Sonine transform technique are noted. (author)

  12. PHAST Version 2-A Program for Simulating Groundwater Flow, Solute Transport, and Multicomponent Geochemical Reactions

    Science.gov (United States)

    Parkhurst, David L.; Kipp, Kenneth L.; Charlton, Scott R.

    2010-01-01

    The computer program PHAST (PHREEQC And HST3D) simulates multicomponent, reactive solute transport in three-dimensional saturated groundwater flow systems. PHAST is a versatile groundwater flow and solute-transport simulator with capabilities to model a wide range of equilibrium and kinetic geochemical reactions. The flow and transport calculations are based on a modified version of HST3D that is restricted to constant fluid density and constant temperature. The geochemical reactions are simulated with the geochemical model PHREEQC, which is embedded in PHAST. Major enhancements in PHAST Version 2 allow spatial data to be defined in a combination of map and grid coordinate systems, independent of a specific model grid (without node-by-node input). At run time, aquifer properties are interpolated from the spatial data to the model grid; regridding requires only redefinition of the grid without modification of the spatial data. PHAST is applicable to the study of natural and contaminated groundwater systems at a variety of scales ranging from laboratory experiments to local and regional field scales. PHAST can be used in studies of migration of nutrients, inorganic and organic contaminants, and radionuclides; in projects such as aquifer storage and recovery or engineered remediation; and in investigations of the natural rock/water interactions in aquifers. PHAST is not appropriate for unsaturated-zone flow, multiphase flow, or density-dependent flow. A variety of boundary conditions are available in PHAST to simulate flow and transport, including specified-head, flux (specified-flux), and leaky (head-dependent) conditions, as well as the special cases of rivers, drains, and wells. Chemical reactions in PHAST include (1) homogeneous equilibria using an ion-association or Pitzer specific interaction thermodynamic model; (2) heterogeneous equilibria between the aqueous solution and minerals, ion exchange sites, surface complexation sites, solid solutions, and gases; and

  13. Solute transport and storage mechanisms in wetlands of the Everglades, south Florida

    Science.gov (United States)

    Harvey, Judson W.; Saiers, James E.; Newlin, Jessica T.

    2005-01-01

    Solute transport and storage processes in wetlands play an important role in biogeochemical cycling and in wetland water quality functions. In the wetlands of the Everglades, there are few data or guidelines to characterize transport through the heterogeneous flow environment. Our goal was to conduct a tracer study to help quantify solute exchange between the relatively fast flowing water in the open part of the water column and much more slowly moving water in thick floating vegetation and in the pore water of the underlying peat. We performed a tracer experiment that consisted of a constant‐rate injection of a sodium bromide (NaBr) solution for 22 hours into a 3 m wide, open‐ended flume channel in Everglades National Park. Arrival of the bromide tracer was monitored at an array of surface water and subsurface samplers for 48 hours at a distance of 6.8 m downstream of the injection. A one‐dimensional transport model was used in combination with an optimization code to identify the values of transport parameters that best explained the tracer observations. Parameters included dimensions and mass transfer coefficients describing exchange with both short (hours) and longer (tens of hours) storage zones as well as the average rates of advection and longitudinal dispersion in the open part of the water column (referred to as the “main flow zone”). Comparison with a more detailed set of tracer measurements tested how well the model's storage zones approximated the average characteristics of tracer movement into and out of the layer of thick floating vegetation and the pore water in the underlying peat. The rate at which the relatively fast moving water in the open water column was exchanged with slowly moving water in the layer of floating vegetation and in sediment pore water amounted to 50 and 3% h−1, respectively. Storage processes decreased the depth‐averaged velocity of surface water by 50% relative to the water velocity in the open part of the water

  14. A biomechanical triphasic approach to the transport of nondilute solutions in articular cartilage.

    Science.gov (United States)

    Abazari, Alireza; Elliott, Janet A W; Law, Garson K; McGann, Locksley E; Jomha, Nadr M

    2009-12-16

    Biomechanical models for biological tissues such as articular cartilage generally contain an ideal, dilute solution assumption. In this article, a biomechanical triphasic model of cartilage is described that includes nondilute treatment of concentrated solutions such as those applied in vitrification of biological tissues. The chemical potential equations of the triphasic model are modified and the transport equations are adjusted for the volume fraction and frictional coefficients of the solutes that are not negligible in such solutions. Four transport parameters, i.e., water permeability, solute permeability, diffusion coefficient of solute in solvent within the cartilage, and the cartilage stiffness modulus, are defined as four degrees of freedom for the model. Water and solute transport in cartilage were simulated using the model and predictions of average concentration increase and cartilage weight were fit to experimental data to obtain the values of the four transport parameters. As far as we know, this is the first study to formulate the solvent and solute transport equations of nondilute solutions in the cartilage matrix. It is shown that the values obtained for the transport parameters are within the ranges reported in the available literature, which confirms the proposed model approach.

  15. Quadrupole transport experiment with space charge dominated cesium ion beam

    International Nuclear Information System (INIS)

    Faltens, A.; Keefe, D.; Kim, C.; Rosenblum, S.; Tiefenback, M.; Warwick, A.

    1984-08-01

    The purpose of the experiment is to investigate the beam current transport limit in a long quadrupole-focussed transport channel in the space charge dominated region where the space charge defocussing force is almost as large as the average focussing force of the channel

  16. Solute transport in a well under slow-purge and no-purge conditions

    Science.gov (United States)

    Plummer, M. A.; Britt, S. L.; Martin-Hayden, J. M.

    2010-12-01

    Non-purge sampling techniques, such as diffusion bags and in-situ sealed samplers, offer reliable and cost-effective groundwater monitoring methods that are a step closer to the goal of real-time monitoring without pumping or sample collection. Non-purge methods are, however, not yet completely accepted because questions remain about how solute concentrations in an unpurged well relate to concentrations in the adjacent formation. To answer questions about how undisturbed well water samples compare to formation concentrations, and to provide the information necessary to interpret results from non-purge monitoring systems, we have conducted a variety of physical experiments and numerical simulations of flow and transport in and through monitoring wells under low-flow and ambient flow conditions. Previous studies of flow and transport in wells used a Darcy’s law - based continuity equation for flow, which is often justified under the strong, forced-convection flow caused by pumping or large vertical hydraulic potential gradients. In our study, we focus on systems with weakly forced convection, where density-driven free convection may be of similar strength. We therefore solved Darcy’s law for porous media domains and the Navier Stokes equations for flow in the well, and coupled solution of the flow equations to that of solute transport. To illustrate expected in-well transport behavior under low-flow conditions, we present results of three particular studies: (1) time-dependent effluent concentrations from a well purged at low-flow pumping rates, (2) solute-driven density effects in a well under ambient horizontal flow and (3) temperature-driven mixing in a shallow well subject to seasonal temperature variations. Results of the first study illustrate that assumptions about the nature of in-well flow have a significant impact on effluent concentration curves even during pumping, with Poiseuille-type flow producing more rapid removal of concentration differences

  17. PHAST--a program for simulating ground-water flow, solute transport, and multicomponent geochemical reactions

    Science.gov (United States)

    Parkhurst, David L.; Kipp, Kenneth L.; Engesgaard, Peter; Charlton, Scott R.

    2004-01-01

    The computer program PHAST simulates multi-component, reactive solute transport in three-dimensional saturated ground-water flow systems. PHAST is a versatile ground-water flow and solute-transport simulator with capabilities to model a wide range of equilibrium and kinetic geochemical reactions. The flow and transport calculations are based on a modified version of HST3D that is restricted to constant fluid density and constant temperature. The geochemical reactions are simulated with the geochemical model PHREEQC, which is embedded in PHAST. PHAST is applicable to the study of natural and contaminated ground-water systems at a variety of scales ranging from laboratory experiments to local and regional field scales. PHAST can be used in studies of migration of nutrients, inorganic and organic contaminants, and radionuclides; in projects such as aquifer storage and recovery or engineered remediation; and in investigations of the natural rock-water interactions in aquifers. PHAST is not appropriate for unsaturated-zone flow, multiphase flow, density-dependent flow, or waters with high ionic strengths. A variety of boundary conditions are available in PHAST to simulate flow and transport, including specified-head, flux, and leaky conditions, as well as the special cases of rivers and wells. Chemical reactions in PHAST include (1) homogeneous equilibria using an ion-association thermodynamic model; (2) heterogeneous equilibria between the aqueous solution and minerals, gases, surface complexation sites, ion exchange sites, and solid solutions; and (3) kinetic reactions with rates that are a function of solution composition. The aqueous model (elements, chemical reactions, and equilibrium constants), minerals, gases, exchangers, surfaces, and rate expressions may be defined or modified by the user. A number of options are available to save results of simulations to output files. The data may be saved in three formats: a format suitable for viewing with a text editor; a

  18. One-dimensional spatially dependent solute transport in semi ...

    African Journals Online (AJOL)

    Space dependent retardation factor is also taken. The nature of porous media and solute pollutant are considered chemically non-reactive. Initially porous domain is considered solute free and the input source condition is considered uniformly continuous. A new transformation is introduced to solve the advection dispersion ...

  19. Pore connectivity effects on solute transport in rocks

    International Nuclear Information System (INIS)

    Hu, Qinhong; Ewing, Robert P.

    2001-01-01

    Retardation of nuclear contaminants in rock matrices can lead to long retention times, allowing substantial radionuclide decay prior to eventual release. Imbibition and diffusion into the rock matrix can move contaminants away from an active fracture, thereby contributing to their retardation. However, diffusive transport in some rocks may behave anomalously because of their sparsely connected porespace, in contrast to diffusion in rocks with denser pore connections. We examined imbibition of weakly sorbing tracers into welded tuff and Indiana sandstone, and water imbibition into metagraywacke and Berea sandstone. Tuff samples were initially equilibrated to 12% and 76% water (v/v) within controlled humidity chambers, while the other rocks were air-dried. For imbibition, one face was exposed to water, with or without tracer, and uptake was measured over time. Following imbibition, tracer concentration measurements were made at fine (1 mm) increments. Three anomalous results were observed: (1) Indiana sandstone and metagraywacke showed mass of imbibed water scaling as time 0.26 , while tuff and Berea sandstone showed the more classical scaling with time 0.5 ; (2) tracer movement into dry (2% initial saturation) Indiana sandstone showed a dispersion pattern similar to that expected during tracer movement into moist (76% initial saturation) tuff; and (3) tracer concentrations at the inlet face of the tuff sample were approximately twice those deeper inside the sample. The experiment was then modeled using random walk methods on a 3-D lattice with different values of pore coordination. Network model simulations that used a pore coordination of 1.49 for Indiana sandstone and 1.56 for metagraywacke showed similar temporal scaling, a result of their porespace being close to the percolation threshold. Tracer concentration profiles in Indiana sandstone and tuff were closely matched by simulations that used pore coordinations of 1.49 and 1.68, respectively, because of how low

  20. Pore Connectivity Effects on Solute Transport in Rocks

    International Nuclear Information System (INIS)

    Oinhong Hu

    2001-01-01

    Retardation of nuclear contaminants in rock matrices can lead to long retention times, allowing substantial radionuclide decay prior to eventual release. Imbibition and diffusion into the rock matrix can move contaminants away from an active fracture, thereby contributing to their retardation. However, diffusive transport in some rocks may behave anomalously because of their sparsely connected porespace, in contrast to diffusion in rocks with denser pore connections. We examined imbibition of weakly sorbing tracers into welded tuff and Indiana sandstone, and water imbibition into metagraywacke and Berea sandstone. Tuff samples were initially equilibrated to 12% and 76% water (v/v) within controlled humidity chambers, while the other rocks were air-dried. For imbibition, one face was exposed to water, with or without tracer, and uptake was measured over time. Following imbibition, tracer concentration measurements were made at fine (1 mm) increments. Three anomalous results were observed: (1) Indiana sandstone and metagraywacke showed mass of imbibed water scaling as time 0.26 , while tuff and Berea sandstone showed the more classical scaling with time 0.05 ; (2) tracer movement into dry (2% initial saturation) Indiana sandstone showed a dispersion pattern similar to that expected during tracer movement into moist (76% initial saturation) tuft and (3) tracer concentrations at the inlet face of the tuff sample were approximately twice those deeper inside the sample. The experiment was then modeled using random walk methods on a 3-D lattice with different values of pore coordination. Network model simulations that used a pore coordination of 1.49 for Indiana sandstone and 1.56 for metagraywacke showed similar temporal scaling, a result of their porespace being close to the percolation threshold. Tracer concentration profiles in Indiana sandstone and tuff were closely matched by simulations that used pore coordinations of 1.49 and 1.68, respectively, because of how low

  1. 30 years of experience in safe transportation of nuclear materials

    International Nuclear Information System (INIS)

    Kaneko, K.

    2004-01-01

    In April 2003, Nuclear Fuel Transport Co., Ltd. (NFT) marked the 30 th anniversary of its founding. NFT was established in 1973 and in 1978, commenced SF transport to the reprocessing plant in Tokai-mura. And then, after making preparations to transport nuclear materials to the various facilities at the Nuclear Fuel Cycle Center in Rokkasho-mura, NFT successfully started transportation of LLW (low level waste) to Rokksho-mura's LLW disposal center in 1992, domestic land transportation of HLW returned from overseas to the HLW storage center in 1995, domestic land transportation of natural hexafluoride delivered from overseas to the uranium enrichment plant in 1996, and transportation of SF to the reprocessing plant in 2000. NFT has realized an annual SF transportation capacity of 300 MTU and is currently making great company wide efforts to meet the Rokkasho Reprocessing Plant's future SF annual reprocessing capacity of 800MTU. At the end of FY2003, NFT had successfully transported 560 casks (about 1,730 MTU) of SF in more than 200 voyages in total, about 160,000 drums of LLW in around 100 voyages in total. This paper introduces the record of safe transport and its experience over the past 30 years and prospect for future transport business

  2. Spent fuel and HLW transportation the French experience

    International Nuclear Information System (INIS)

    Giraud, J.P.; Charles, J.L.

    1995-01-01

    With 53 nuclear power plants in operation at EDF and a fuel cycle with recycling policy of the valuable materials, COGEMA is faced with the transport of a wide range of radioactive materials. In this framework, the transport activity is a key link in closing the fuel cycle. COGEMA has developed a comprehensive Transport Organization System dealing with all the sectors of the fuel cycle. The paper will describe the status of transportation of spent fuel and HLW in France and the experience gathered. The Transport Organization System clearly defines the role of all actors where COGEMA, acting as the general coordinator, specifies the tasks to be performed and brings technical and commercial support to its various subcontractors: TRANSNUCLEAIRE, specialized in casks engineering and transport operations, supplies packaging and performs transport operations, LEMARECHAL and CELESTIN operate transport by truck in the Vicinity of the nuclear sites while French Railways are in charge of spent fuel transport by train. HLW issued from the French nuclear program is stored for 30 years in an intermediate storage installation located at the La Hague reprocessing plant. Ultimately, these canisters will be transported to the disposal site. COGEMA has set up a comprehensive transport organization covering all operational aspects including adapted procedures, maintenance programs and personnel qualification

  3. 30 years of experience in safe transportation of nuclear materials

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, K. [Nuclear Fuel Transport Co., Ltd., Tokyo (Japan)

    2004-07-01

    In April 2003, Nuclear Fuel Transport Co., Ltd. (NFT) marked the 30{sup th} anniversary of its founding. NFT was established in 1973 and in 1978, commenced SF transport to the reprocessing plant in Tokai-mura. And then, after making preparations to transport nuclear materials to the various facilities at the Nuclear Fuel Cycle Center in Rokkasho-mura, NFT successfully started transportation of LLW (low level waste) to Rokksho-mura's LLW disposal center in 1992, domestic land transportation of HLW returned from overseas to the HLW storage center in 1995, domestic land transportation of natural hexafluoride delivered from overseas to the uranium enrichment plant in 1996, and transportation of SF to the reprocessing plant in 2000. NFT has realized an annual SF transportation capacity of 300 MTU and is currently making great company wide efforts to meet the Rokkasho Reprocessing Plant's future SF annual reprocessing capacity of 800MTU. At the end of FY2003, NFT had successfully transported 560 casks (about 1,730 MTU) of SF in more than 200 voyages in total, about 160,000 drums of LLW in around 100 voyages in total. This paper introduces the record of safe transport and its experience over the past 30 years and prospect for future transport business.

  4. JET internal transport barriers: experiment vs theory

    Energy Technology Data Exchange (ETDEWEB)

    Esposito, B [Associazione Euratom - ENEA sulla Fusione, C.R. Frascati, CP 65, I-00040, Frascati, Rome (Italy); Crisanti, F [Associazione Euratom - ENEA sulla Fusione, C.R. Frascati, CP 65, I-00040, Frascati, Rome (Italy); Parail, V [Euratom/UKAEA Fusion Association, Cuhlam Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Maget, P [Association Euratom - CEA pour la Fusion, CEA Cadarache, F-13108 Saint Paul-lez-Durance Cedex (France); Baranov, Y [Euratom/UKAEA Fusion Association, Cuhlam Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Becoulet, A [Association Euratom - CEA pour la Fusion, CEA Cadarache, F-13108 Saint Paul-lez-Durance Cedex (France); Castaldo, C [Associazione Euratom - ENEA sulla Fusione, C.R. Frascati, CP 65, I-00040, Frascati, Rome (Italy); Challis, C D [Euratom/UKAEA Fusion Association, Cuhlam Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Angelis, R De [Associazione Euratom - ENEA sulla Fusione, C.R. Frascati, CP 65, I-00040, Frascati, Rome (Italy); Garbet, X [Association Euratom - CEA pour la Fusion, CEA Cadarache, F-13108 Saint Paul-lez-Durance Cedex (France); Giroud, C [Association Euratom - CEA pour la Fusion, CEA Cadarache, F-13108 Saint Paul-lez-Durance Cedex (France); Hawkes, N [Euratom/UKAEA Fusion Association, Cuhlam Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Joffrin, E [Association Euratom - CEA pour la Fusion, CEA Cadarache, F-13108 Saint Paul-lez-Durance Cedex (France); Litaudon, X [Association Euratom - CEA pour la Fusion, CEA Cadarache, F-13108 Saint Paul-lez-Durance Cedex (France); Mazon, D [Association Euratom - CEA pour la Fusion, CEA Cadarache, F-13108 Saint Paul-lez-Durance Cedex (France); Riva, M [Associazione Euratom - ENEA sulla Fusione, C.R. Frascati, CP 65, I-00040, Frascati, Rome (Italy); Zastrow, K D [Euratom/UKAEA Fusion Association, Cuhlam Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)

    2003-06-01

    A large variety of JET discharges with internal transport barriers (ITBs) has been analysed in order to determine the main features which characterize turbulence stabilization at the barrier. It is found that the location of barriers is well correlated with regions where the ExB flow shearing rate exceeds the linear growth rate of the ion temperature gradient mode instability ({gamma}{sub {eta}{sub i}}). A key point is the dependence of {gamma}{sub {eta}{sub i}} on the magnetic shear: in the discharges of this database the reduction of {gamma}{sub {eta}{sub i}} associated to very low or null magnetic shear favours the formation of an ITB. After the ITB formation a positive feedback occurs in which the ExB flow shear mechanism has the leading role and the position of the barrier may be no longer linked to the low shear region.

  5. Transport simulations of ohmic ignition experiment: IGNITEX

    International Nuclear Information System (INIS)

    Uckan, N.A.; Howe, H.C.

    1987-01-01

    The IGNITEX device, proposed by Rosenbluth et al., is a compact, super-high-field, high-current, copper-coil tokamak envisioned to reach ignition with ohmic (OH) heating alone. Several simulations of IGNITEX were made with a 0-D global model and with the 1-D PROCTR transport code. It is shown that OH ignition is a sensitive function of the assumptions about density profile, wall reflectivity of synchrotron radiation, impurity radiation, plasma edge conditions, and additional anomalous losses. In IGNITEX, OH ignition is accessible with nearly all scalings based on favorable OH confinement (such as neo-Alcator). Also, OH ignition appears to be accessible for most (not all) L-mode scalings (such as Kaye-Goldston), provided that the density profile is not too broad (parabolic or more peaked profiles are needed), Z/sub eff/ is not too large (≤2), and anomalous radiation and alpha losses and/or other enhanced transport losses (/eta//sub i/ modes, edge convective energy losses, etc.) are not present. In IGNITEX, because the figure-of-merit parameters (aB 0 2 /q* /approximately/ IB 0 , etc.) are large, ignition can be accessed (either with OH heating alone or with the aid of a small amount of auxiliary power) at relatively low beta, far from stability limits. Once the plasma is ignited, thermal runaway is prevented naturally by a combination of increased synchrotron radiation, burnout of the fuel in the plasma core and replacement by thermal alphas, and the reduction in the thermal plasma confinement assumed in L-mode-like scalings. 12 refs., 5 figs., 1 tab

  6. Transport simulations of ohmic ignition experiment: IGNITEX

    International Nuclear Information System (INIS)

    Uckan, N.A.; Howe, H.C.

    1987-12-01

    The IGNITEX device, proposed by Rosenbluth et al., is a compact, super-high-field, high-current, copper-coil tokamak envisioned to reach ignition with ohmic (OH) heating alone. Several simulations of IGNITEX were made with a 0-D global model and with the 1-D PROCTR transport code. It is shown that OH ignition is a sensitive function of the assumptions about density profile, wall reflectivity of synchrotron radiation, impurity radiation, plasma edge conditions, and additional anomalous losses. In IGNITEX, OH ignition is accessible with nearly all scalings based on favorable OH confinement (such as neo-Alcator). Also, OH ignition appears to be accessible for most (not all) L-mode scalings (such as Kaye-Goldston), provided that the density profile is not too broad (parabolic or more peaked profiles are needed), Z/sub eff/ is not too large, and anomalous radiation and alpha losses and/or other enhanced transport losses (eta/sub i/ modes, edge convective energy losses, etc.) are not present. In IGNITEX, because the figure-of-merit parameters are large, ignition can be accessed (either with OH heating alone or with the aid of a small amount of auxiliary power) at relatively low beta, far from stability limits. Once the plasma is ignited, thermal runaway is prevented naturally by a combination of increased synchrotron radiation, burnout of the fuel in the plasma core and replacement by thermal alphas, and the reduction in the thermal plasma confinement assumed in L-mode-like scalings. 12 refs., 5 figs., 1 tab

  7. Experience feedback from the transportation of Framatome fuel assemblies

    International Nuclear Information System (INIS)

    Robin, M.E.; Gaillard, G.; Aubin, C.

    1998-01-01

    Framatome, the foremost world nuclear fuel manufacturer, has for 25 years been delivering fuel elements from its three factories (Dessel, Romans, Pierrelatte) to the various sites in France and abroad (Germany, Sweden, Belgium, China, Korea, South Africa, Switzerland). During this period, Framatome has built up experience and expertise in fuel element transportation by road, rail and sea. In this filed, the range of constraints is very wide: safety and environmental protection constraints; constraints arising from the control and protection of nuclear materials, contractual and financial constraints, media watchdogs. Through the experience feedback from the transportation of FRAMATOME assemblies, this paper addresses all the phases in the transportation of fresh fuel assemblies. (authors)

  8. DOE's foreign research reactor transportation services contract: Perspective and experience

    International Nuclear Information System (INIS)

    Patterson, John

    1997-01-01

    DOE committed to low- and moderate-income countries participating in the foreign research reactor spent fuel returns program that the United States government would provide for the transportation of the spent fuel. In fulfillment of that commitment, DOE entered into transportation services contracts with qualified, private-sector firms. NAC will discuss its experience as a transportation services provider, including range of services available to the foreign reactors, advantages to DOE and to the foreign research reactors, access to contract services by high income countries and potential advantages, and experience with initial tasks performed under the contract. (author)

  9. Experience and prospects of WWER-1000 reactor spent fuel transport

    International Nuclear Information System (INIS)

    Kondratyev, A.N.; Yershov, V.N.; Kozlov, Yu.V.; Kosarev, Yu.A.; Ilyin, Yu.V.; Pavlov, M.S.

    1989-01-01

    The paper deals with the USSR experience in shipping the commercial WWER-1000 reactor spent fuel in TK-10 and TK-13 casks. The cask designs, their basic characteristics and the WWER-1000 spent fuel features are described. An example of calculational/experimental approach in the design of a basket (one of the most important components) for spent fuel assembly (SFA) accommodation in a cask is given. The main problems of future development works are presented in brief. A concept of development of nuclear power industry with the closed fuel cycle is assumed in the Soviet Union, hence the spent nuclear fuel is to be transported from NPPs to reprocessing plants. To transport WWER-1000 spent fuel, the casks of two types were developed. These are: a pilot TK-10 cask of 3t capacity in fuel; a commercial TK-13 cask of ∼6t capacity in fuel. The pilot TK-10 cask is thick-walled (360mm) cylindrical vessel manufactured of steel shells and a bottom welded to each other. The material of the body is carbon steel. There is a steel jacket on the outer side of the cask body and at 120 mm distance off the bottom. On its cylindrical part between the jacket and the body there are T-shaped circular ribs acting as shock-absorbers. The space between the jacket and the body is filled with ethylene glycol solution of 65 degree C crystallization temperature, which functions as a neutron shielding. The TK-10 cask coolant is water or air (nitrogen) at minor excess pressure resulted from FA heatup after the cask sealing

  10. Comparison of three labeled silica nanoparticles used as tracers in transport experiments in porous media. Part II: Transport experiments and modeling

    International Nuclear Information System (INIS)

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

    2014-01-01

    Three types of labeled silica nanoparticles were used in transport experiments in saturated sand. The goal of this study was to evaluate both the efficiency of labeling techniques (fluorescence (FITC), metal (Ag(0) core) and radioactivity ( 110m Ag(0) core)) in realistic transport conditions and the reactive transport of silica nanocolloids of variable size and concentration in porous media. Experimental results obtained under contrasted experimental conditions revealed that deposition in sand is controlled by nanoparticles size and ionic strength of the solution. A mathematical model is proposed to quantitatively describe colloid transport. Fluorescent labeling is widely used to study fate of colloids in soils but was the less sensitive one. Ag(0) labeling with ICP-MS detection was found to be very sensitive to measure deposition profiles. Radiolabeled ( 110m Ag(0)) nanoparticles permitted in situ detection. Results obtained with radiolabeled nanoparticles are wholly original and might be used for improving the modeling of deposition and release dynamics. -- Highlights: • Three kinds of labeled nanotracers were used in transport experiments in sand columns. • They were used as surrogates of silica nanoparticles or mineral colloid. • Deposition depending on colloid size and ionic strength was observed and modeled. • Fluorescence labeling had the worse detection limit but was the more convenient. • Radiolabeled nanotracers were detected in situ in a non destructive way. -- Follow the kinetics of transport, deposition and release of silica nanoparticles with suitably labeled nanoparticles

  11. Solute transport processes in a highly permeable fault zone of Lindau fractured rock test site (Germany)

    Energy Technology Data Exchange (ETDEWEB)

    Himmelsbach, T. [Ruhr-Univ., Bochum (Germany). Dept. of Applied Geology; Hoetzl, H. [Univ. of Karlsruhe (Germany). Dept. of Applied Geology; Maloszewski, P. [GSF-Inst. for Hydrology, Munich-Neuherberg (Germany)

    1998-09-01

    The results of field tracer experiments performed in the Lindau fractured rock test site (southern Black Forest, Germany) and subsequent modeling are presented. A vertical, hydrothermally mineralized fault zone, with a permeability much greater than the surrounding granite mass, lies beneath a planned dam site. A dense network of boreholes and tunnels were used to investigate scaling effects of solute transport processes in fractured rock. A series of tracer experiments using deuterium and dye tracers were performed over varying distances and under different testing procedures, resulting in different flow field conditions. Large-scale tracer experiments were performed under natural flow field conditions, while small-scale tracer experiments were performed under artificially induced radial-convergent and injection-withdrawal flow fields. The tracer concentration curves observed in all experiments were strongly influenced by the matrix diffusion. The curves were evaluated with the one-dimensional single fissure dispersion model (SFDM) adjusted for the different flow field conditions. The fitting model parameters found determined the fracture aperture, and matrix and fissure porosities. The determined fracture aperture varied between the sections having different hydraulic conductivity. The determined values of matrix porosity seemed to be independent of the scale of the experiment. The modeled matrix porosities agreed well with values determined in independent laboratory investigations of drill cores using mercury porosimetry. In situ fissure porosity, determined only in small-scale experiments, was independent of the applied geometry of the artificially induced flow fields. The dispersivities were found to be independent of the scale of experiment but dependent on the flow conditions. The values found in forced gradient tests lie between 0.2 and 0.3 m, while values in experiments performed under natural flow conditions were one order of magnitude higher.

  12. Light-driven solute transport in Halobacterium halobium

    Science.gov (United States)

    Lanyi, J. K.

    1979-01-01

    The cell membrane of Halobacterium halobium exhibits differential regions which contain crystalline arrays of a single kind of protein, termed bacteriorhodopsin. This bacterial retinal-protein complex resembles the visual pigment and, after the absorption of protons, translocates H(+) across the cell membrane, leading to an electrochemical gradient for protons between the inside and the outside of the cell. Thus, light is an alternate source of energy in these bacteria, in addition to terminal oxidation. The paper deals with work on light-driven transport in H. halobium with cell envelope vesicles. The discussion covers light-driven movements of H(+), Na(+), and K(+); light-driven amino acid transport; and apparent allosteric control of amino acid transport. The scheme of energy coupling in H. halobium vesicles appears simple, its quantitative details are quite complex and reveal regulatory phenomena. More knowledge is required of the way the coupling components are regulated by the ion gradients present.

  13. Effects of Solution Chemistry on Nano-Bubbles Transport in Saturated Porous Media

    Science.gov (United States)

    Hamamoto, S.; Takemura, T.; Suzuki, K.; Nihei, N.; Nishimura, T.

    2017-12-01

    Nano-bubbles (NBs) have a considerable potential for the remediation of soil and groundwater contaminated by organic compounds, especially when used in conjunction with bioremediation technologies. Understanding the transport mechanisms of NBs in soils is essential to optimize NB-based remediation techniques. In this study, one-dimensional column transport experiments using glass beads with 0.1 mm size were conducted, where NBs created by oxygen gas at different pH and ionic strength were injected to the column at the constant flow rate. The NBs concentration in the effluent was quantified using a resonant mass measurement technique. Effects of solution chemistry of the NBs water on NB transport in the porous media were investigated. The results showed that attachment of NBs was enhanced under higher ionic strength and lower pH conditions, caused by the reduced repulsive force between NBs and glass beads. In addition, bubble size distributions in the effluents showed that relatively larger NBs were retained in the column. This trend was more significant at lower pH condition.

  14. Brine transport in porous media self-similar solutions

    NARCIS (Netherlands)

    C.J. van Duijn (Hans); L.A. Peletier (Bert); R.J. Schotting (Ruud)

    1996-01-01

    textabstractIn this paper we analyze a model for brine transport in porous media, which includes a mass balance for the fluid, a mass balance for salt, Darcy's law and an equation of state, which relates the fluid density to the salt mass fraction. This model incorporates the effect of local volume

  15. Solute transport through porous media using asymptotic dispersivity

    Indian Academy of Sciences (India)

    ber of processes and porous media properties including convective transport .... existence of regions within the porous medium in which there is minimum advective flow. .... concentration at x = L. The initial and the exit boundary conditions can be .... rial was cleaned, washed and dried to ensure that the material free from ...

  16. Activity Coefficients of Acetone-Chloroform Solutions: An Undergraduate Experiment. Undergraduate Experiment.

    Science.gov (United States)

    Ozog, J. Z.; Morrison, J. A.

    1983-01-01

    Presents information, laboratory procedures, and results of an undergraduate experiment in which activity coefficients for a two-component liquid-vapor system are determined. Working in pairs, students can perform the experiment with 10 solutions in a given three-hour laboratory period. (Author/JN)

  17. Reactive solute transport in an asymmetrical fracture-rock matrix system

    Science.gov (United States)

    Zhou, Renjie; Zhan, Hongbin

    2018-02-01

    The understanding of reactive solute transport in a single fracture-rock matrix system is the foundation of studying transport behavior in the complex fractured porous media. When transport properties are asymmetrically distributed in the adjacent rock matrixes, reactive solute transport has to be considered as a coupled three-domain problem, which is more complex than the symmetric case with identical transport properties in the adjacent rock matrixes. This study deals with the transport problem in a single fracture-rock matrix system with asymmetrical distribution of transport properties in the rock matrixes. Mathematical models are developed for such a problem under the first-type and the third-type boundary conditions to analyze the spatio-temporal concentration and mass distribution in the fracture and rock matrix with the help of Laplace transform technique and de Hoog numerical inverse Laplace algorithm. The newly acquired solutions are then tested extensively against previous analytical and numerical solutions and are proven to be robust and accurate. Furthermore, a water flushing phase is imposed on the left boundary of system after a certain time. The diffusive mass exchange along the fracture/rock matrixes interfaces and the relative masses stored in each of three domains (fracture, upper rock matrix, and lower rock matrix) after the water flushing provide great insights of transport with asymmetric distribution of transport properties. This study has the following findings: 1) Asymmetric distribution of transport properties imposes greater controls on solute transport in the rock matrixes. However, transport in the fracture is mildly influenced. 2) The mass stored in the fracture responses quickly to water flushing, while the mass stored in the rock matrix is much less sensitive to the water flushing. 3) The diffusive mass exchange during the water flushing phase has similar patterns under symmetric and asymmetric cases. 4) The characteristic distance

  18. The effect of low-GDP solution on ultrafiltration and solute transport in continuous ambulatory peritoneal dialysis patients.

    Science.gov (United States)

    Cho, Kyu-Hyang; Do, Jun-Young; Park, Jong-Won; Yoon, Kyung-Woo; Kim, Yong-Lim

    2013-01-01

    Several studies have reported benefits for human peritoneal mesothelial cell function of a neutral-pH dialysate low in glucose degradation products (GDPs). However, the effects of low-GDP solution on ultrafiltration (UF), transport of solutes, and control of body water remain elusive. We therefore investigated the effect of low-GDP solution on UF, solute transport, and control of body water. Among 79 new continuous ambulatory peritoneal dialysis (CAPD) patients, 60 completed a 12-month protocol (28 in a lactate-based high-GDP solution group, 32 in a lactate-based low-GDP solution group). Clinical indices--including 24-hour UF volume (UFV), 24-hour urine volume (UV), residual renal function, and dialysis adequacy--were measured at months 1, 6, and 12. At months 1, 6, and 12, UFV, glucose absorption, 4-hour dialysate-to-plasma (D/P) creatinine, and 1-hour D/P Na(+) were assessed during a modified 4.25% peritoneal equilibration test (PET). Body composition by bioelectric impedance analysis was measured at months 1 and 12 in 26 CAPD patients. Daily UFV was lower in the low-GDP group. Despite similar solute transport and aquaporin function, the low-GDP group also showed lower UFV and higher glucose absorption during the PET. Factors associated with UFV during the PET were lactate-based high-GDP solution and 1-hour D/P Na(+). No differences in volume status and obesity at month 12 were observed, and improvements in hypervolemia were equal in both groups. Compared with the high-GDP group, the low-GDP group had a lower UFV during a PET and a lower daily UFV during the first year after peritoneal dialysis initiation. Although the low-GDP group had a lower daily UFV, no difficulties in controlling edema were encountered.

  19. Solution approach for a large scale personnel transport system for a large company in Latin America

    Energy Technology Data Exchange (ETDEWEB)

    Garzón-Garnica, Eduardo-Arturo; Caballero-Morales, Santiago-Omar; Martínez-Flores, José-Luis

    2017-07-01

    The present paper focuses on the modelling and solution of a large-scale personnel transportation system in Mexico where many routes and vehicles are currently used to service 525 points. The routing system proposed can be applied to many cities in the Latin-American region. Design/methodology/approach: This system was modelled as a VRP model considering the use of real-world transit times, and the fact that routes start at the farthest point from the destination center. Experiments were performed on different sized sets of service points. As the size of the instances was increased, the performance of the heuristic method was assessed in comparison with the results of an exact algorithm, the results remaining very close between both. When the size of the instance was full-scale and the exact algorithm took too much time to solve the problem, then the heuristic algorithm provided a feasible solution. Supported by the validation with smaller scale instances, where the difference between both solutions was close to a 6%, the full –scale solution obtained with the heuristic algorithm was considered to be within that same range. Findings: The proposed modelling and solving method provided a solution that would produce significant savings in the daily operation of the routes. Originality/value: The urban distribution of the cities in Latin America is unique to other regions in the world. The general layout of the large cities in this region includes a small town center, usually antique, and a somewhat disordered outer region. The lack of a vehicle-centered urban planning poses distinct challenges for vehicle routing problems in the region. The use of a heuristic VRP combined with the results of an exact VRP, allowed the obtention of an improved routing plan specific to the requirements of the region.

  20. Solution approach for a large scale personnel transport system for a large company in Latin America

    International Nuclear Information System (INIS)

    Garzón-Garnica, Eduardo-Arturo; Caballero-Morales, Santiago-Omar; Martínez-Flores, José-Luis

    2017-01-01

    The present paper focuses on the modelling and solution of a large-scale personnel transportation system in Mexico where many routes and vehicles are currently used to service 525 points. The routing system proposed can be applied to many cities in the Latin-American region. Design/methodology/approach: This system was modelled as a VRP model considering the use of real-world transit times, and the fact that routes start at the farthest point from the destination center. Experiments were performed on different sized sets of service points. As the size of the instances was increased, the performance of the heuristic method was assessed in comparison with the results of an exact algorithm, the results remaining very close between both. When the size of the instance was full-scale and the exact algorithm took too much time to solve the problem, then the heuristic algorithm provided a feasible solution. Supported by the validation with smaller scale instances, where the difference between both solutions was close to a 6%, the full –scale solution obtained with the heuristic algorithm was considered to be within that same range. Findings: The proposed modelling and solving method provided a solution that would produce significant savings in the daily operation of the routes. Originality/value: The urban distribution of the cities in Latin America is unique to other regions in the world. The general layout of the large cities in this region includes a small town center, usually antique, and a somewhat disordered outer region. The lack of a vehicle-centered urban planning poses distinct challenges for vehicle routing problems in the region. The use of a heuristic VRP combined with the results of an exact VRP, allowed the obtention of an improved routing plan specific to the requirements of the region.

  1. Solution approach for a large scale personnel transport system for a large company in Latin America

    Directory of Open Access Journals (Sweden)

    Eduardo-Arturo Garzón-Garnica

    2017-10-01

    Full Text Available Purpose: The present paper focuses on the modelling and solution of a large-scale personnel transportation system in Mexico where many routes and vehicles are currently used to service 525 points. The routing system proposed can be applied to many cities in the Latin-American region. Design/methodology/approach: This system was modelled as a VRP model considering the use of real-world transit times, and the fact that routes start at the farthest point from the destination center. Experiments were performed on different sized sets of service points. As the size of the instances was increased, the performance of the heuristic method was assessed in comparison with the results of an exact algorithm, the results remaining very close between both.  When the size of the instance was full-scale and the exact algorithm took too much time to solve the problem, then the heuristic algorithm provided a feasible solution. Supported by the validation with smaller scale instances, where the difference between both solutions was close to a 6%, the full –scale solution obtained with the heuristic algorithm was considered to be within that same range. Findings: The proposed modelling and solving method provided a solution that would produce significant savings in the daily operation of the routes. Originality/value: The urban distribution of the cities in Latin America is unique to other regions in the world. The general layout of the large cities in this region includes a small town center, usually antique, and a somewhat disordered outer region. The lack of a vehicle-centered urban planning poses distinct challenges for vehicle routing problems in the region. The use of a heuristic VRP combined with the results of an exact VRP, allowed the obtention of an improved routing plan specific to the requirements of the region.

  2. Diverging diamond interchange, results from the right transportation solution survey : staff summary, January 2010.

    Science.gov (United States)

    2010-01-01

    Based on the results from this research, MoDOT can confidently state that the diverging diamond was the right transportation solution for the Interstate 44 and Route 13 intersection. The overall results show: Most Springfield area residents were ...

  3. Exact and Numerical Solutions of a Spatially-Distributed Mathematical Model for Fluid and Solute Transport in Peritoneal Dialysis

    Directory of Open Access Journals (Sweden)

    Roman Cherniha

    2016-06-01

    Full Text Available The nonlinear mathematical model for solute and fluid transport induced by the osmotic pressure of glucose and albumin with the dependence of several parameters on the hydrostatic pressure is described. In particular, the fractional space available for macromolecules (albumin was used as a typical example and fractional fluid void volume were assumed to be different functions of hydrostatic pressure. In order to find non-uniform steady-state solutions analytically, some mathematical restrictions on the model parameters were applied. Exact formulae (involving hypergeometric functions for the density of fluid flux from blood to tissue and the fluid flux across tissues were constructed. In order to justify the applicability of the analytical results obtained, a wide range of numerical simulations were performed. It was found that the analytical formulae can describe with good approximation the fluid and solute transport (especially the rate of ultrafiltration for a wide range of values of the model parameters.

  4. Brain washing : Transport of cerebral extracellular fluids and solutes

    NARCIS (Netherlands)

    Bedussi, B.

    2017-01-01

    Regulation of extracellular volume and fluid composition provides a robust microenvironment for brain cells. In peripheral tissue, fluid surplus and solutes are removed from the interstitium via drainage into lymphatic channels. Since the central nervous system lacks a proper lymphatic vasculature,

  5. Microfluidic model experiments on the injectability of monoclonal antibody solutions

    Science.gov (United States)

    Duchene, Charles; Filipe, Vasco; Nakach, Mostafa; Huille, Sylvain; Lindner, Anke

    2017-11-01

    Autoinjection devices that allow patients to self-administer medicine are becoming used more frequently; however, this advance comes with an increased need for precision in the injection process. The rare occurrence of protein aggregates in solutions of monoclonal antibodies constitutes a threat to the reliability of such devices. Here we study the flow of protein solutions containing aggregates in microfluidic model systems, mimicking injection devices, to gain fundamental understanding of the catastrophic clogging of constrictions of given size. We form aggregates by mechanically shaking or heating antibody solutions and then inject these solutions into microfluidic channels with varying types of constrictions. Geometrical clogging occurs when aggregates reach the size of the constriction and can in some cases be undone by increasing the applied pressure. We perform systematic experiments varying the relative aggregate size and the flow rate or applied pressure. The mechanical deformation of aggregates during their passage through constrictions is investigated to gain a better understanding of the clogging and unclogging mechanisms.

  6. A compartmentalized solute transport model for redox zones in contaminated aquifers: 1. Theory and development

    Science.gov (United States)

    Abrams , Robert H.; Loague, Keith

    2000-01-01

    This paper, the first of two parts [see Abrams and Loague, this issue], takes the compartmentalized approach for the geochemical evolution of redox zones presented by Abrams et al. [1998] and embeds it within a solute transport framework. In this paper the compartmentalized approach is generalized to facilitate the description of its incorporation into a solute transport simulator. An equivalent formulation is developed which removes any discontinuities that may occur when switching compartments. Rate‐limited redox reactions are modeled with a modified Monod relationship that allows either the organic substrate or the electron acceptor to be the rate‐limiting reactant. Thermodynamic constraints are used to inhibit lower‐energy redox reactions from occurring under infeasible geochemical conditions without imposing equilibrium on the lower‐energy reactions. The procedure used allows any redox reaction to be simulated as being kinetically limited or thermodynamically limited, depending on local geochemical conditions. Empirical reaction inhibition methods are not needed. The sequential iteration approach (SIA), a technique which allows the number of solute transport equations to be reduced, is adopted to solve the coupled geochemical/solute transport problem. When the compartmentalized approach is embedded within the SIA, with the total analytical concentration of each component as the dependent variable in the transport equation, it is possible to reduce the number of transport equations even further than with the unmodified SIA. A one‐dimensional, coupled geochemical/solute transport simulation is presented in which redox zones evolve dynamically in time and space. The compartmentalized solute transport (COMPTRAN) model described in this paper enables the development of redox zones to be simulated under both kinetic and thermodynamic constraints. The modular design of COMPTRAN facilitates the use of many different, preexisting solute transport and

  7. Fluid flow and convective transport of solutes within the intervertebral disc.

    Science.gov (United States)

    Ferguson, Stephen J; Ito, Keita; Nolte, Lutz P

    2004-02-01

    Previous experimental and analytical studies of solute transport in the intervertebral disc have demonstrated that for small molecules diffusive transport alone fulfils the nutritional needs of disc cells. It has been often suggested that fluid flow into and within the disc may enhance the transport of larger molecules. The goal of the study was to predict the influence of load-induced interstitial fluid flow on mass transport in the intervertebral disc. An iterative procedure was used to predict the convective transport of physiologically relevant molecules within the disc. An axisymmetric, poroelastic finite-element structural model of the disc was developed. The diurnal loading was divided into discrete time steps. At each time step, the fluid flow within the disc due to compression or swelling was calculated. A sequentially coupled diffusion/convection model was then employed to calculate solute transport, with a constant concentration of solute being provided at the vascularised endplates and outer annulus. Loading was simulated for a complete diurnal cycle, and the relative convective and diffusive transport was compared for solutes with molecular weights ranging from 400 Da to 40 kDa. Consistent with previous studies, fluid flow did not enhance the transport of low-weight solutes. During swelling, interstitial fluid flow increased the unidirectional penetration of large solutes by approximately 100%. Due to the bi-directional temporal nature of disc loading, however, the net effect of convective transport over a full diurnal cycle was more limited (30% increase). Further study is required to determine the significance of large solutes and the timing of their delivery for disc physiology.

  8. Two decades' experience with interfacility transport on extracorporeal membrane oxygenation.

    Science.gov (United States)

    Bryner, Benjamin; Cooley, Elaine; Copenhaver, William; Brierley, Kristin; Teman, Nicholas; Landis, Denise; Rycus, Peter; Hemmila, Mark; Napolitano, Lena M; Haft, Jonathan; Park, Pauline K; Bartlett, Robert H

    2014-10-01

    Interfacility transport of patients on extracorporeal membrane oxygenation (ECMO) has been performed in large numbers at only a few programs. Limited data are available on outcomes after ECMO transport to justify expanding or discontinuing these programs. This was a retrospective review of a 20-year, single-institution experience with interhospital ECMO transport as well as a systematic review of reports of transfers of patients on ECMO. Results of both were compared with historical data from the international registry of the Extracorporeal Life Support Organization (ELSO). Between 1990 and 2012, ECMO was used to facilitate transport of 221 patients to our institution, and 135 (62%) survived to discharge. Review of an additional 27 case series describing ECMO transport of 643 patients showed an overall survival of 61%. After stratifying by age and primary indication for ECMO, survival of transported patients was not significantly different compared with all ECMO patients in the ELSO registry, with the exception of pediatric patients treated for respiratory failure (transported patients in this category had higher survival than those in the ELSO registry). Interfacility transport on ECMO is feasible and can be accomplished safely in the critically ill. Survival of transported patients is comparable to age-matched and treatment-matched ECMO patients at large. Copyright © 2014 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  9. TLC scheme for numerical solution of the transport equation on equilateral triangular meshes

    International Nuclear Information System (INIS)

    Walters, W.F.

    1983-01-01

    A new triangular linear characteristic TLC scheme for numerically solving the transport equation on equilateral triangular meshes has been developed. This scheme uses the analytic solution of the transport equation in the triangle as its basis. The data on edges of the triangle are assumed linear as is the source representation. A characteristic approach or nodal approach is used to obtain the analytic solution. Test problems indicate that the new TLC is superior to the widely used DITRI scheme for accuracy

  10. Water flow and solute transport through fractured rock

    International Nuclear Information System (INIS)

    Bolt, J.E.; Bourke, P.J.; Pascoe, D.M.; Watkins, V.M.B.; Kingdon, R.D.

    1990-09-01

    In densely fractured slate at the Nirex research site in Cornwall, the positions, orientations and hydraulic conductivities of the 380 fractures intersecting a drill hole between 9 and 50 m depth have been individually measured. These data have been used: to determine the dimensions of statistically representative volumes of the network of fractures and to predict, using discrete flow path modelling and the NAPSAC code, the total flows into the fractures when large numbers are simultaneously pressurised along various lengths of the hole. Corresponding measurements, which validated the NAPSAC code to factor of two accuracy for the Cornish site, are reported. Possibilities accounting for this factor are noted for experimental investigation, and continuing, more extensive, inter hole flow and transport measurements are outlined. The application of this experimental and theoretical approach for calculating radionuclide transport in less densely fractured rock suitable for waste disposal is discussed. (Author)

  11. Water flow and solute transport through fractured rock

    International Nuclear Information System (INIS)

    Bourke, P.J.; Kingdon, R.D.; Bolt, J.E.; Pascoe, D.M.; Watkins, V.M.B.

    1991-01-01

    In densely fractured slate at the Nirex research site in Cornwall, the positions, orientations and hydraulic conductivities of the 380 fractures intersecting a drill hole between 9 and 50 m depths have been individually measured. These data have been used: - to determine the dimensions of statistically representative volumes of the sheetwork of fractures; - to predict; using discrete flowpath modelling and the NAPSAC code; the total flows into the fractures when large numbers are simultaneously pressurised along various lengths of the hole; Corresponding measurements, which proved the modelling and validated the code to factor of two accuracy, are reported. Possibilities accounting for this factor are noted for experimental investigation, and continuing, more extensive inter-hole flow and transport measurements are outlined. The application of this experimental and theoretical approach for calculating radionuclide transport in less densely fractured rock suitable for waste disposal is discussed. 7 figs., 9 refs

  12. Closed-flow column experiments—Insights into solute transport provided by a damped oscillating breakthrough behavior

    Science.gov (United States)

    Ritschel, Thomas; Totsche, Kai Uwe

    2016-03-01

    Transport studies that employ column experiments in closed-flow mode complement classical approaches by providing new characteristic features observed in the solute breakthrough and equilibrium between liquid and solid phase. Specific to the closed-flow mode is the recirculation of the effluent to the inflow via a mixing vessel. Depending on the ratio of volumes of mixing vessel and water-filled pore space, a damped oscillating solute concentration emerges in the effluent and mixing vessel. The oscillation characteristics, e.g., frequency, amplitude, and damping, allow for the investigation of solute transport in a similar fashion as known for classical open-flow column experiments. However, the closed loop conserves substances released during transport within the system. In this way, solute and porous medium can equilibrate with respect to physicochemical conditions. With this paper, the features emerging in the breakthrough curves of saturated column experiments run in closed-flow mode and methods of evaluation are illustrated under experimental boundary conditions forcing the appearance of oscillations. We demonstrate that the effective pore water volume and the pumping rate can be determined from a conservative tracer breakthrough curve uniquely. In this way, external preconditioning of the material, e.g., drying, can be avoided. A reactive breakthrough experiment revealed a significant increase in the pore water pH value as a consequence of the closed loop. These results highlight the specific impact of the closed mass balance. Furthermore, the basis for the modeling of closed-flow experiments is given by the derivation of constitutive equations and numerical implementation, validated with the presented experiments.

  13. A transportronic solution to the problem of interorbital transportation

    Science.gov (United States)

    Brown, William C.

    1992-01-01

    An all-electronic transportation system described by the term 'transportronics' is examined as a means of solving the current problem of the high cost of transporting material from low-Earth orbit (LEO) to geostationary orbit (GEO). In this transportation system, low cost electric energy at the surface of the Earth is efficiently converted into microwave power which is then efficiently formed into a narrow beam which is kept incident upon the orbital transfer vehicles (OTV's) by electronic tracking. The incident beam is efficiently captured and converted into DC power by a device which has a very high ratio of DC power output to its mass. Because the mass of the electric thruster is also low, the resulting acceleration is unprecedented for electric-propelled vehicles. However, the performance of the system in terms of transit times from LEO to GEO is penalized by the short time of contact between the beam and the vehicle in low-Earth orbits. This makes it necessary to place the Earth based transmitters and the vehicles in the equatorial plane thus introducing many geopolitical factors. Technically, however, such a system as described in the report may out-perform any other approach to transportation in the LEO to GEO regime. The report describes and analyzes all portions of the beamed microwave power transmission system in considerable detail. An economic analysis of the operating and capital costs is made with the aid of a reference system capable of placing about 130,000 kilograms of payload into GEO each year. More mature states of the system are then examined, to a level in which 60,000 metric tons per year could be placed into GEO.

  14. How ISCO Can Interfere in Soil Pore Distribution and Solute Transport

    Science.gov (United States)

    Favero, M.; Freitas, J. G.; Furquim, S. A. C.; Thomson, N. R.; Cooper, M.

    2016-12-01

    Recently in situ chemical oxidation (ISCO) has been a remedy of choice for sites contaminated with organic compounds. However, the impact of the chemical oxidant on soil properties and, therefore, on solute transport and remediation efficiency still lacks understanding. This research effort sought to evaluate the changes in soil physical properties and solute transport behavior in a typical tropical soil (Oxisol) resulting from exposure to persulfate. The Oxisol used had a microaggregate structure, resulting in a relatively high hydraulic conductivity despite the high clay content (67%). One-dimensional laboratory experiments were performed using a saturated undisturbed column. The injection of an ideal tracer (bromide), a reactive tracer (phenol) and persulfate (12 ± 1 gL-1 for 30 d) were performed consecutively. The tracer tests were repeated following persulfate injection. Transport parameters (longitudinal dispersivity: αL and retardation factor: R) and the effective porosity (ne) were obtained by fitting the breakthrough curves with an analytical solution for one-dimensional transport. Micromorphological analyses of porosity were conducted on impregnated soil blocks from control and oxidized systems. The bromide and phenol tracer test data yielded αL of 2.431 ± 0.002 cm, ne of 41.99 ± 1.52 %, R of 1.10, and a first-order decay rate coefficient of 6.5x10-5 min-1 prior to persulfate exposure. The effluent persulfate concentration stabilized at C/Co of 0.8 after 4 d of injection and the breakthrough was delayed relative to bromide. Concurrent with the breakthrough of persulfate, the pH decreased and a progressive release of Al (III) over the first 4 d with subsequent stabilization were observed. Following persulfate exposures the hydraulic conductivity increased about one-order of magnitude. Micromorphological analysis showed that persulfate produced alterations in poroids types, with an increase of complex packing voids. It was verified that persulfate

  15. Numerical fluid solutions for nonlocal electron transport in hot plasmas: Equivalent diffusion versus nonlocal source

    International Nuclear Information System (INIS)

    Colombant, Denis; Manheimer, Wallace

    2010-01-01

    Flux limitation and preheat are important processes in electron transport occurring in laser produced plasmas. The proper calculation of both of these has been a subject receiving much attention over the entire lifetime of the laser fusion project. Where nonlocal transport (instead of simple single flux limit) has been modeled, it has always been with what we denote the equivalent diffusion solution, namely treating the transport as only a diffusion process. We introduce here a new approach called the nonlocal source solution and show it is numerically viable for laser produced plasmas. It turns out that the equivalent diffusion solution generally underestimates preheat. Furthermore, the advance of the temperature front, and especially the preheat, can be held up by artificial 'thermal barriers'. The nonlocal source method of solution, on the other hand more accurately describes preheat and can stably calculate the solution for the temperature even if the heat flux is up the gradient.

  16. Conceptual and numerical models of groundwater flow and solute transport in fracture zones: Application to the Aspo Island (Sweden)

    International Nuclear Information System (INIS)

    Molinero, J.; Samper, J.

    2003-01-01

    Several countries around the world are considering the final disposal of high-level radioactive waste in deep repositories located in fractured granite formations. Evaluating the long term safety of such repositories requires sound conceptual and numerical models which must consider simultaneously groundwater flow, solute transport and chemical and radiological processes. These models are being developed from data and knowledge gained from in situ experiments carried out at deep underground laboratories such as that of Aspo, Sweden, constructed in fractured granite. The Redox Zone Experiment is one of such experiments performed at Aspo in order to evaluate the effects of the construction of the access tunnel on the hydrogeological and hydrochemical conditions of a fracture zone intersected by the tunnel. Previous authors interpreted hydrochemical and isotopic data of this experiment using a mass-balance approach based on a qualitative description of groundwater flow conditions. Such an interpretation, however, is subject to uncertainties related to an over-simplified conceptualization of groundwater flow. Here we present numerical models of groundwater flow and solute transport for this fracture zone. The first model is based on previously published conceptual model. It presents noticeable un consistencies and fails to match simultaneously observed draw downs and chloride breakthrough curves. To overcome its limitations, a revised flow and transport model is presented which relies directly on available hydrodynamic and transport parameters, is based on the identification of appropriate flow and transport boundary conditions and uses, when needed, solute data extrapolated from nearby fracture zones. A significant quantitative improvement is achieved with the revised model because its results match simultaneously drawdown and chloride data. Other improvements are qualitative and include: ensuring consistency of hydrodynamic and hydrochemical data and avoiding

  17. Experimental quantification of solute transport through the vadose zone under dynamic boundary conditions with dye tracers and optical methods.

    Science.gov (United States)

    Cremer, Clemens; Neuweiler, Insa

    2017-04-01

    Knowledge of subsurface solute transport processes is vital to investigate e.g. groundwater contamination, nutrient uptake by plant roots and to implement remediation strategies. Beside field measurements and numerical simulations, physical laboratory experiments represent a way to establish process understanding and furthermore validate numerical schemes. Atmospheric forcings, such as erratically varying infiltration and evaporation cycles, subject the shallow subsurface to local and temporal variations in water content and associated hydraulic conductivity of the prevailing porous media. Those variations in material properties can cause flow paths to differ between upward and downward flow periods. Thereby, the unsaturated subsurface presents a highly complicated, dynamic system. Following an extensive systematical numerical investigation of flow and transport through bimodal, unsaturated porous media under dynamic boundary conditions (Cremer et al., 2016), we conduct physical laboratory experiments in a 22 cm x 8 cm x 1 cm flow cell where we introduce structural heterogeneity in the form sharp material interfaces between different porous media. In all experiments, a constant pressure head is implemented at the lower boundary, while cyclic infiltration-evaporation phases are applied at the soil surface. As a reference case a stationary infiltration with a rate corresponding to the cycle-averaged infiltration rate is applied. By initial application of dye tracers, solute transport within the domain is visualized such that transport paths and redistribution processes can be observed in a qualitative manner. Solute leaching is quantified at the bottom outlet, where breakthrough curves are obtained via spectroscopy. Liquid and vapor flow in and out of the domain is obtained from multiple balances. Thereby, the interplay of material structural heterogeneity and alternating flow (transport) directions and flow (transport) paths is investigated. Results show lateral

  18. Meta-analysis of the effects of soil properties, site factors and experimental conditions on solute transport

    Directory of Open Access Journals (Sweden)

    J. K. Koestel

    2012-06-01

    Full Text Available Preferential flow is a widespread phenomenon that is known to strongly affect solute transport in soil, but our understanding and knowledge is still poor of the site factors and soil properties that promote it. To investigate these relationships, we assembled a database from the peer-reviewed literature containing information on 733 breakthrough curve experiments under steady-state flow conditions. Most of the collected experiments (585 of the 733 datasets had been conducted on undisturbed soil columns, although some experiments on repacked soil, clean sands, and glass beads were also included. In addition to the apparent dispersivity, we focused our attention on three indicators of preferential solute transport: namely the 5%-arrival time, the holdback factor, and the ratio of piston-flow and average transport velocities. Our results suggest that, in contrast to the 5%-arrival time and the holdback factor, the piston-flow to transport velocity ratio is not related to preferential macropore transport but rather to the exclusion or retardation of the applied tracer. Confirming that the apparent longitudinal dispersivity is positively correlated with the travel distance of the tracer, our results also illustrate that this relationship is refined if the normalized 5%-tracer arrival time is also taken into account. In particular, we found that the degree of preferential solute transport increases with apparent dispersivity and decreases with travel distance. A similar but weaker relationship was observed between apparent dispersivity, 5%-tracer arrival time, and lateral observation scale, such that the degree of preferential transport increases with lateral observation scale. However, we also found that the travel distance and the lateral observation scale in the investigated dataset are correlated, which makes it difficult to distinguish their influence on these transport characteristics. We also found that the strength of preferential transport

  19. First experience in international air transportation of RR SFA in Russian-made TUK-19 casks

    International Nuclear Information System (INIS)

    Kanashov, B.A.; Barinkov, O.P.; Dorofeev, A.N.; Komarov, S.V.; Smirnov, A.V.; Biro, L.; Budu, M.; Ciocanescu, M.

    2010-01-01

    Traditionally, spent fuel assemblies (SFA) have been transported across the Russian Federation by rail in special railcars. New conditions required SFA shipments by other conveyance, i.e. road, sea and even air transport. The air shipment of the VVR-S research reactor SNF in TUK-19 casks from Magurele, Romania in June 2009 was the first experience after new Russian and international regulations for the safe transport of radioactive material came into effect. The preparatory stage of the shipment focused on the issues associated with radiation and nuclear safety both during the loading and transport operations. The project covered development of a technology and equipment for SFA loading into TUK-19 casks and that for the air shipment. The SFAs were loaded into the TUK-19 casks with a specially designed transfer cask, and the SFA-containing packages were transported in specialized freight 20-foot ISO-containers. The safety of the loading and transport operations was ensured both by reliable engineering solutions, and selected conveyances and routes. The paper shows that the loading and the air shipment of the Romanian SFAs in TUK-19 casks does not contradict Romanian, Russian and international regulations for the safe transport of radioactive material. The outcomes of the SNF shipment from Romania confirmed correctness of the solutions and demonstrated high environmental safety. (author)

  20. Solution High-Energy Burst Assembly (SHEBA) results from subprompt critical experiments with uranyl fluoride fuel

    International Nuclear Information System (INIS)

    Cappiello, C.C.; Butterfield, K.B.; Sanchez, R.G.

    1997-10-01

    The Solution High-Energy Burst Assembly (SHEBA) was originally constructed during 1980 and was designed to be a clean free-field geometry, right-circular, cylindrically symmetric critical assembly employing U(5%)O 2 F 2 solution as fuel. A second version of SHEBA, employing the same fuel but equipped with a fuel pump and shielding pit, was commissioned in 1993. This report includes data and operating experience for the 1993 SHEBA only. Solution-fueled benchmark work focused on the development of experimental measurements of the characterization of SHEBA; a summary of the results are given. A description of the system and the experimental results are given in some detail in the report. Experiments were designed to: (1) study the behavior of nuclear excursions in a low-enrichment solution, (2) evaluate accidental criticality alarm detectors for fuel-processing facilities, (3) provide radiation spectra and dose measurements to benchmark radiation transport calculations on a low-enrichment solution system similar to centrifuge enrichment plants, and (4) provide radiation fields to calibrate personnel dosimetry. 15 refs., 37 figs., 10 tabs

  1. The Governor's Challenge: "Building a Stronger Virginia Today": Transportation Visions and Solutions

    Science.gov (United States)

    Baker, Susan

    2008-01-01

    Using STM(Science, Technology, Engineering, Math) education, this emerging workforce will have the chance to creatively solve one of Virginia's biggest challenges: TRANSPORTATION. - Students will be asked to develop alternative transportation systems for the state. This competition will enable teams to work with business mentors to design creative solutions for regional gridlocks and develop other transportation systems to more easily and expediently reach all parts of the Commonwealth.

  2. Solute transport in streams of varying morphology inferred from a high resolution network of potentiometric wireless chloride sensors

    Science.gov (United States)

    Klaus, Julian; Smettem, Keith; Pfister, Laurent; Harris, Nick

    2017-04-01

    There is ongoing interest in understanding and quantifying the travel times and dispersion of solutes moving through stream environments, including the hyporheic zone and/or in-channel dead zones where retention affects biogeochemical cycling processes that are critical to stream ecosystem functioning. Modelling these transport and retention processes requires acquisition of tracer data from injection experiments where the concentrations are recorded downstream. Such experiments are often time consuming and costly, which may be the reason many modelling studies of chemical transport have tended to rely on relatively few well documented field case studies. This leads to the need of fast and cheap distributed sensor arrays that respond instantly and record chemical transport at points of interest on timescales of seconds at various locations in the stream environment. To tackle this challenge we present data from several tracer experiments carried out in the Attert river catchment in Luxembourg employing low-cost (in the order of a euro per sensor) potentiometric chloride sensors in a distributed array. We injected NaCl under various baseflow conditions in streams of different morphologies and observed solute transport at various distances and locations. This data is used to benchmark the sensors to data obtained from more expensive electrical conductivity meters. Furthermore, the data allowed spatial resolution of hydrodynamic mixing processes and identification of chemical 'dead zones' in the study reaches.

  3. New solution for transport and industrial noise protection through reflective noise barriers

    Directory of Open Access Journals (Sweden)

    Kralov Ivan

    2017-01-01

    Full Text Available A new solution for protection of transportation and industrial noise through reflective noise barriers is proposed and investigated in this study. The new solution combines the advantages of the known barriers and has its own advantages in addition. The preliminary results show a very good level of noise reduction for this type of barriers.

  4. Large time behaviour of oscillatory nonlinear solute transport in porous media

    NARCIS (Netherlands)

    Duijn, van C.J.; Zee, van der S.E.A.T.M.

    2018-01-01

    Oscillations in flow occur under many different situations in natural porous media, due to tidal, daily or seasonal patterns. In this paper, we investigate how such oscillations in flow affect the transport of an initially sharp solute front, if the solute undergoes nonlinear sorption and,

  5. Reactive silica transport in fractured porous media: Analytical solutions for a system of parallel fractures

    Science.gov (United States)

    Yang, Jianwen

    2012-04-01

    A general analytical solution is derived by using the Laplace transformation to describe transient reactive silica transport in a conceptualized 2-D system involving a set of parallel fractures embedded in an impermeable host rock matrix, taking into account of hydrodynamic dispersion and advection of silica transport along the fractures, molecular diffusion from each fracture to the intervening rock matrix, and dissolution of quartz. A special analytical solution is also developed by ignoring the longitudinal hydrodynamic dispersion term but remaining other conditions the same. The general and special solutions are in the form of a double infinite integral and a single infinite integral, respectively, and can be evaluated using Gauss-Legendre quadrature technique. A simple criterion is developed to determine under what conditions the general analytical solution can be approximated by the special analytical solution. It is proved analytically that the general solution always lags behind the special solution, unless a dimensionless parameter is less than a critical value. Several illustrative calculations are undertaken to demonstrate the effect of fracture spacing, fracture aperture and fluid flow rate on silica transport. The analytical solutions developed here can serve as a benchmark to validate numerical models that simulate reactive mass transport in fractured porous media.

  6. Modelling solute dispersion in periodic heterogeneous porous media: Model benchmarking against intermediate scale experiments

    Science.gov (United States)

    Majdalani, Samer; Guinot, Vincent; Delenne, Carole; Gebran, Hicham

    2018-06-01

    This paper is devoted to theoretical and experimental investigations of solute dispersion in heterogeneous porous media. Dispersion in heterogenous porous media has been reported to be scale-dependent, a likely indication that the proposed dispersion models are incompletely formulated. A high quality experimental data set of breakthrough curves in periodic model heterogeneous porous media is presented. In contrast with most previously published experiments, the present experiments involve numerous replicates. This allows the statistical variability of experimental data to be accounted for. Several models are benchmarked against the data set: the Fickian-based advection-dispersion, mobile-immobile, multirate, multiple region advection dispersion models, and a newly proposed transport model based on pure advection. A salient property of the latter model is that its solutions exhibit a ballistic behaviour for small times, while tending to the Fickian behaviour for large time scales. Model performance is assessed using a novel objective function accounting for the statistical variability of the experimental data set, while putting equal emphasis on both small and large time scale behaviours. Besides being as accurate as the other models, the new purely advective model has the advantages that (i) it does not exhibit the undesirable effects associated with the usual Fickian operator (namely the infinite solute front propagation speed), and (ii) it allows dispersive transport to be simulated on every heterogeneity scale using scale-independent parameters.

  7. Specific transport and storage solutions: Waste management facing current and future stakes of the nuclear fuel cycle

    International Nuclear Information System (INIS)

    Deniau, Helene; Gagner, Laurent; Gendreau, Francoise; Presta, Anne

    2006-01-01

    development process; - Current solutions proposed by COGEMA LOGISTICS; - Transport of Low Level and Very Low Level waste (LLW and VLLW); - Shipment of large volumes; - Non-reusable transport packaging; - Packaging transport permit the storage in final disposal area; - A steep increase of transport flows in the next 10 years; - Future challenges, waste from dismantling operations; - Transport packaging of IP 2 type and IP 2 package; - Some examples of standardized packages; - DV78 Package; - CC102 over pack; - A solution for liquid waste from NPPs, TNTMCIEL; - Transport of Intermediate Level Waste (ILW) and High Level Waste (HLW); - Alpha waste (or TRU waste); - TNTMGEMINI; - RD 26 package; - Bituminized waste (ILW): the TNTM833; - Technological waste in CBFC'2 (ILW): the TNTM837; - Universal Canisters for Vitrified waste (HLW) and Compacted waste (ILW); - Vitrified waste (HLW); - Transport solutions for CSD-V canisters: the TNTM28 VT; - Dual purpose solutions for CSD-V canisters, the TS 28; - CSD-V programme of return; - Compacted waste (ILW): the TNTM843; - Some future stakes and new developments. The following conclusions completes the paper. COGEMA LOGISTICS experience in designing packages and transporting nuclear materials is part of the COGEMA / AREVA waste management policy, which aims to waste volume reduction through waste sorting and packaging in universal canisters or standard waste containers. For the design and manufacture of special shipping casks, as for nuclear transportation and storage, COGEMA LOGISTICS tailors its solutions to its international customers' requirements. Personnel safety, transportation safety and environmental protection are put first. These reasons have lead COGEMA LOGISTICS to become the world's leading designer of nuclear fuel packages, with unique expertise in designing packages for back-end transportation and storage of nuclear materials. Beyond being a transport company and packaging designer, COGEMA LOGISTICS is a partner implementing

  8. Carrier mediated transport through supported liquid membranes; determination of transport parameters from a single transport experiment

    NARCIS (Netherlands)

    Chrisstoffels, L.A.J.; Struijk, Wilhelmina; de Jong, Feike; Reinhoudt, David

    1996-01-01

    This paper describes a time-dependent transport model for carrier assisted cation transport through supported liquid membranes. The model describes the flux of salt as a function of time and two parameters viz. the diffusion coefficient of the cation complex (D), and the extraction constant (Kex).

  9. Ruthenium transport experiments in air ingress accident conditions

    Energy Technology Data Exchange (ETDEWEB)

    Teemu, Karkele; Ulrika, Backman; Ari, Auvinen; Unto, Tapper; Jorma, Jokiniemi [VTT Technical Research Centre of Finland, Fine Particles (Finland); Riitta, Zilliacus; Maija, Lipponen; Tommi, Kekki [VTT Technical Research Centre of Finland, Accident Management (Finland); Jorma, Jokiniemi [Kuopio Univ., Dept. of Environmental Sciences, Fine Particle and Aerosol Technology Lab. (Finland)

    2007-07-01

    In this study the release, transport and speciation of ruthenium in conditions simulating an air ingress accident was studied. Ruthenium dioxide was exposed to oxidising environment at high temperature (1100-1700 K) in a tubular flow furnace. At these conditions volatile ruthenium species were formed. A large fraction of the released ruthenium was deposited in the tube as RuO{sub 2}. Depending on the experimental conditions 1-26 wt% of the released ruthenium was trapped in the outlet filter as RuO{sub 2} particles. In stainless steel tube 0-8.8 wt% of the released ruthenium reached the trapping bottle as gaseous RuO{sub 4}. A few experiments were carried out, in which revaporization of ruthenium deposited on the tube walls was studied. In these experiments, oxidation of RuO{sub 2} took place at a lower temperature. During revaporization experiments 35-65 % of ruthenium was transported as gaseous RuO{sub 4}. In order to close mass balance and achieve better time resolution 4 experiments were carried out using a radioactive tracer. In these experiments ruthenium profiles were measured. These experiments showed that the most important retention mechanism was decomposition of gaseous RuO{sub 3} into RuO{sub 2} as the temperature of the furnace was decreasing. In these experiments the transport rate of gaseous ruthenium was decreasing while the release rate was constant.

  10. Reactive transport in a partially molten system with binary solid solution

    Science.gov (United States)

    Jordan, J.; Hesse, M. A.

    2017-12-01

    Melt extraction from the Earth's mantle through high-porosity channels is required to explain the composition of the oceanic crust. Feedbacks from reactive melt transport are thought to localize melt into a network of high-porosity channels. Recent studies invoke lithological heterogeneities in the Earth's mantle to seed the localization of partial melts. Therefore, it is necessary to understand the reaction fronts that form as melt flows across the lithological interface of a heterogeneity and the background mantle. Simplified melting models of such systems aide in the interpretation and formulation of larger scale mantle models. Motivated by the aforementioned facts, we present a chromatographic analysis of reactive melt transport across lithological boundaries, using theory for hyperbolic conservation laws. This is an extension of well-known linear trace element chromatography to the coupling of major elements and energy transport. Our analysis allows the prediction of the feedbacks that arise in reactive melt transport due to melting, freezing, dissolution and precipitation for frontal reactions. This study considers the simplified case of a rigid, partially molten porous medium with binary solid solution. As melt traverses a lithological contact-modeled as a Riemann problem-a rich set of features arise, including a reacted zone between an advancing reaction front and partial chemical preservation of the initial contact. Reactive instabilities observed in this study originate at the lithological interface rather than along a chemical gradient as in most studies of mantle dynamics. We present a regime diagram that predicts where reaction fronts become unstable, thereby allowing melt localization into high-porosity channels through reactive instabilities. After constructing the regime diagram, we test the one-dimensional hyperbolic theory against two-dimensional numerical experiments. The one-dimensional hyperbolic theory is sufficient for predicting the

  11. Integrated compartmental model for describing the transport of solute in a fractured porous medium. [FRACPORT

    Energy Technology Data Exchange (ETDEWEB)

    DeAngelis, D.L.; Yeh, G.T.; Huff, D.D.

    1984-10-01

    This report documents a model, FRACPORT, that simulates the transport of a solute through a fractured porous matrix. The model should be useful in analyzing the possible transport of radionuclides from shallow-land burial sites in humid environments. The use of the model is restricted to transport through saturated zones. The report first discusses the general modeling approach used, which is based on the Integrated Compartmental Method. The basic equations of solute transport are then presented. The model, which assumes a known water velocity field, solves these equations on two different time scales; one related to rapid transport of solute along fractures and the other related to slower transport through the porous matrix. FRACPORT is validated by application to a simple example of fractured porous medium transport that has previously been analyzed by other methods. Then its utility is demonstrated in analyzing more complex cases of pulses of solute into a fractured matrix. The report serves as a user's guide to FRACPORT. A detailed description of data input, along with a listing of input for a sample problem, is provided. 16 references, 18 figures, 3 tables.

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

    International Nuclear Information System (INIS)

    Brusseau, M.L.

    1990-01-01

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

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

    KAUST Repository

    Zhao, Kui

    2016-07-13

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

  14. VS2DRTI: Simulating Heat and Reactive Solute Transport in Variably Saturated Porous Media.

    Science.gov (United States)

    Healy, Richard W; Haile, Sosina S; Parkhurst, David L; Charlton, Scott R

    2018-01-29

    Variably saturated groundwater flow, heat transport, and solute transport are important processes in environmental phenomena, such as the natural evolution of water chemistry of aquifers and streams, the storage of radioactive waste in a geologic repository, the contamination of water resources from acid-rock drainage, and the geologic sequestration of carbon dioxide. Up to now, our ability to simulate these processes simultaneously with fully coupled reactive transport models has been limited to complex and often difficult-to-use models. To address the need for a simple and easy-to-use model, the VS2DRTI software package has been developed for simulating water flow, heat transport, and reactive solute transport through variably saturated porous media. The underlying numerical model, VS2DRT, was created by coupling the flow and transport capabilities of the VS2DT and VS2DH models with the equilibrium and kinetic reaction capabilities of PhreeqcRM. Flow capabilities include two-dimensional, constant-density, variably saturated flow; transport capabilities include both heat and multicomponent solute transport; and the reaction capabilities are a complete implementation of geochemical reactions of PHREEQC. The graphical user interface includes a preprocessor for building simulations and a postprocessor for visual display of simulation results. To demonstrate the simulation of multiple processes, the model is applied to a hypothetical example of injection of heated waste water to an aquifer with temperature-dependent cation exchange. VS2DRTI is freely available public domain software. © 2018, National Ground Water Association.

  15. Optimal solution of full fuzzy transportation problems using total integral ranking

    Science.gov (United States)

    Sam’an, M.; Farikhin; Hariyanto, S.; Surarso, B.

    2018-03-01

    Full fuzzy transportation problem (FFTP) is a transportation problem where transport costs, demand, supply and decision variables are expressed in form of fuzzy numbers. To solve fuzzy transportation problem, fuzzy number parameter must be converted to a crisp number called defuzzyfication method. In this new total integral ranking method with fuzzy numbers from conversion of trapezoidal fuzzy numbers to hexagonal fuzzy numbers obtained result of consistency defuzzyfication on symmetrical fuzzy hexagonal and non symmetrical type 2 numbers with fuzzy triangular numbers. To calculate of optimum solution FTP used fuzzy transportation algorithm with least cost method. From this optimum solution, it is found that use of fuzzy number form total integral ranking with index of optimism gives different optimum value. In addition, total integral ranking value using hexagonal fuzzy numbers has an optimal value better than the total integral ranking value using trapezoidal fuzzy numbers.

  16. The French nuclear safety authority's experience with radioactive transport inspection

    International Nuclear Information System (INIS)

    Jacob, E.; Aguilar, J.

    2004-01-01

    About 300,000 radioactive material packages are transported annually in France. Most consist of radioisotopes for medical, pharmaceutical or industrial use. On the other hand, the nuclear industry deals with the transport of fuel cycle materials (uranium, fuel assemblies, etc.) and waste from power plants, reprocessing plants and research centers. France is also a transit country for shipments such as spent fuel packages from Switzerland or Germany, which are bound for Sellafield in Great Britain. The French nuclear safety authority (DGSNR: Directorate General for Nuclear Safety and Radioprotection) has been responsible since 1997 for the safety of radioactive material transport. This paper presents DGNSR's experience with transport inspection: a feedback of key points based on 300 inspections achieved during the past five years is given

  17. Global stability and exact solution of an arbitrary-solute nonlinear cellular mass transport system.

    Science.gov (United States)

    Benson, James D

    2014-12-01

    The prediction of the cellular state as a function of extracellular concentrations and temperatures has been of interest to physiologists for nearly a century. One of the most widely used models in the field is one where mass flux is linearly proportional to the concentration difference across the membrane. These fluxes define a nonlinear differential equation system for the intracellular state, which when coupled with appropriate initial conditions, define the intracellular state as a function of the extracellular concentrations of both permeating and nonpermeating solutes. Here we take advantage of a reparametrization scheme to extend existing stability results to a more general setting and to a develop analytical solutions to this model for an arbitrary number of extracellular solutes. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. Approximate solution of the transport equation by methods of Galerkin type

    International Nuclear Information System (INIS)

    Pitkaranta, J.

    1977-01-01

    Questions of the existence, uniqueness, and convergence of approximate solutions of transport equations by methods of the Galerkin type (where trial and weighting functions are the same) are discussed. The results presented do not exclude the infinite-dimensional case. Two strategies can be followed in the variational approximation of the transport operator: one proceeds from the original form of the transport equation, while the other is based on the partially symmetrized equation. Both principles are discussed in this paper. The transport equation is assumed in a discretized multigroup form

  19. SOLUTIONS AND MEANS OF ALTERNATIVE TRANSPORT IN THE CONCEPT OF SUSTAINABLE DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    CATALIN POPESCU

    2017-12-01

    Full Text Available The paper aims to achieve an overview of innovative initiatives on alternative transport in recent years in the context of increasing emissions of greenhouse gases. In this context are presented the main problems caused by motorized traffic in the urban agglomerations. Also, there are mentioned measures that could be implemented in busy urban areas. On this occasion are mentioned both new technical solutions and new means of alternative transport type. Additional, specific projects and programs are highlighted using bicycle transportation. There are mentioned initiatives regarding urban transportation completed in European projects such as: CIVITAS, EFFECTS etc. The examples and figures are mainly focused on Romania.

  20. Investigations into co-transport phenomena in PUREX relevant solutions by use of an analytical ultracentrifuge

    International Nuclear Information System (INIS)

    Gauglitz, R.; Marx, G.

    1991-01-01

    The diffusion of the elements uranium, neodymium, chromium, iron, ruthenium was studied in aqueous and aqueous nitric acid solutions. The diffusion of these elements was measured not only under a concentration gradient but also with respect to simultanious nitric and diffusion. Measurements with schlierenoptics and with uv/vis.-optic were carried out at the same time. Besides the diffusion of metal nitrates and potassium dichromate also nitric acid diffusion was investigated. Also in this case apparent diffusion coefficients were determined under concentration gradients and under the influence of superposing element gradients. The diffusion of the elements uranium, neodymium, ruthenium, neptunium and plutonium was also determined in organic systems. At first the transport of the elements was measured under an element gradient, in presence of various amounts of water and nitric acid. These experiments were followed by those on simultanious diffusion of water of nitric acid and elements in TBP/dodecane mixture. Furthermore TBP/dodecane solutions were oxidized with potassium dichromate. This oxidation was measured using a gaschromatograph. From the obtained results the formation rate for the oxidation products could be calculated which proved that higher nitric acid concentrations increased the rate. (orig.) With 16 refs., 100 tabs., 120 figs [de

  1. My Experience. My Perspective. Transportation to Work Presents Problems

    Science.gov (United States)

    Stegers, Markus

    2008-01-01

    Transportation challenges can often be one of the biggest stumbling blocks to having a successful vocational experience. The author presents a personal account of the difficulties people with disabilities encounter in trying to get themselves to their workplaces due to the limitations of various mobility services.

  2. Molecular cell biology and physiology of solute transport

    Science.gov (United States)

    Caplan, Michael J.; Seo-Mayer, Patricia; Zhang, Li

    2010-01-01

    Purpose of review An enormous body of research has been focused on exploring the mechanisms through which epithelial cells establish their characteristic polarity. It is clear that under normal circumstances cell–cell contacts mediated by the calcium-dependent adhesion proteins of the intercellular adhesion junctions are required to initiate complete polarization. Furthermore, formation of the tight, or occluding, junctions that limit paracellular permeability has long been thought to help to establish polarity by preventing the diffusion of membrane proteins between the two plasmalemmal domains. This review will discuss several selected kinases and protein complexes and highlight their relevance to transporting epithelial cell polarization. Recent findings Recent work has shed new light on the roles of junctional complexes in establishing and maintaining epithelial cell polarity. In addition, work from several laboratories, suggests that the formation of these junctions is tied to processes that regulate cellular energy metabolism. Summary Junctional complexes and energy sensing kinases constitute a novel class of machinery whose capacity to generate and modulate epithelial cell polarity is likely to have wide ranging and important physiological ramifications. PMID:18695392

  3. ORGANIZATIONAL STRESS SOURCES AND SOLUTION PROPOSALS IN PUBLIC TRANSPORT

    Directory of Open Access Journals (Sweden)

    Mehmet Zennur GÜRBÜZ

    2017-09-01

    Full Text Available Organizational stress is a concept which can have negative effects for both the workers and the organizations. The purpose of this study is to determine and classify the organizational stress sources that public transportation are exposed to, and to provide suggestions for managing these stress factors. A comprehensive literature survey is made in organizational stress factors and the following classes are identified: work structure, organizational structure, organizational policy, within-company relations and physical conditions. A questionnaire is developed forAnkara EGO General Directorate; applied to 2.137 drivers in Ankara in 2016 with a meaningful return of 1.554 data sets, representing 72% of the population and results are statistically analysed. Descriptive statistics, factor analysis and related validity and regional variance analyses are performed by SPSS (22.0 software. The study revealed that: drivers are exposed to mid-level stess; and most critical stress causes are “injustice and/or insufficiency of salaries”, “aggresive, violent behavior and verbal abuse of passengers towards drivers”, “fear of losing jobs or renewal of the contract”. A significant level of variation in stres levels are identified with respect to different regions of Ankara where drivers are assigned.  Suggestions are made in relation to different stres causes to lower the stress levels exposed.

  4. Generalizing Source Geometry of Site Contamination by Simulating and Analyzing Analytical Solution of Three-Dimensional Solute Transport Model

    Directory of Open Access Journals (Sweden)

    Xingwei Wang

    2014-01-01

    Full Text Available Due to the uneven distribution of pollutions and blur edge of pollutant area, there will exist uncertainty of source term shape in advective-diffusion equation model of contaminant transport. How to generalize those irregular source terms and deal with those uncertainties is very critical but rarely studied in previous research. In this study, the fate and transport of contaminant from rectangular and elliptic source geometry were simulated based on a three-dimensional analytical solute transport model, and the source geometry generalization guideline was developed by comparing the migration of contaminant. The result indicated that the variation of source area size had no effect on pollution plume migration when the plume migrated as far as five times of source side length. The migration of pollution plume became slower with the increase of aquifer thickness. The contaminant concentration was decreasing with scale factor rising, and the differences among various scale factors became smaller with the distance to field increasing.

  5. Modeling reactive geochemical transport of concentrated aqueous solutions in variably saturated media

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guoxiang; Zheng, Zuoping; Wan, Jiamin

    2004-01-28

    Concentrated aqueous solutions (CAS) have unique thermodynamic and physical properties. Chemical components in CAS are incompletely dissociated, especially those containing divalent or polyvalent ions. The problem is further complicated by the interaction between CAS flow processes and the naturally heterogeneous sediments. As the CAS migrates through the porous media, the composition may be altered subject to fluid-rock interactions. To effectively model reactive transport of CAS, we must take into account ion-interaction. A combination of the Pitzer ion-interaction and the ion-association model would be an appropriate way to deal with multiple-component systems if the Pitzer' parameters and thermodynamic data of dissolved components and the related minerals are available. To quantify the complicated coupling of CAS flow and transport, as well as the involved chemical reactions in natural and engineered systems, we have substantially extended an existing reactive biogeochemical transport code, BIO-CORE{sup 2D}{copyright}, by incorporating a comprehensive Pitzer ion-interaction model. In the present paper, the model, and two test cases against measured data were briefly introduced. Finally we present an application to simulate a laboratory column experiment studying the leakage of the high alkaline waste fluid stored in Hanford (a site of the U.S. Department of Energy, located in Washington State, USA). With the Pitzer ion-interaction ionic activity model, our simulation captures measured pH evolution. The simulation indicates that all the reactions controlling the pH evolution, including cation exchanges, mineral precipitation and dissolution, are coupled.

  6. A new treatment of the heat transport equation with a transport barrier and applications to ECRH experiments in Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Zou, X.L.; Giruzzi, A.G.; Bouquey, F.; Clary, J.; Darbos, C.; Lennholm, M.; Magne, R.; Segui, J.L. [CEA Cadarache, Dept. de Recherches sur la Fusion Controlee, 13 - Saint-Paul-lez-Durance (France); Clemencon, A. [MIT, Electrochemical Energy Laboratory, Cambridge, MA (United States); Guivarch, C. [Ecole Nationale des Ponts et Chaussees, 77 - Marne-la-Vallee (France)

    2004-07-01

    An exact analytical solution of the electron heat diffusion equation in a cylinder has been found with a step-like diffusion coefficient, plus a monomial increase in the radial direction and a constant damping term. This model is sufficiently general to describe heat diffusion in the presence of a critical gradient threshold or a transport barrier, superimposed to the usual trend of increasing heat diffusivity from the plasma core to the edge. This type of representation allows us to see some well-known properties of heat transport phenomena in a different light. For instance, it has been shown that the contributions of the Eigenmodes to the time dependent solution grow at speeds that depend on the Eigenmode order i.e. at the beginning of the heating phase all the Eigenmodes are equally involved, whereas at the end only the lower order ones are left. This implies, e.g., that high frequency modulation experiments provide a characterization of transport phenomena that is intrinsically different with respect to power balance analysis of a stationary phase. It is particularly useful to analyse power switch on/off events and whenever high frequency modulations are not technically feasible. Low-frequency (1-2 Hz) ECRH modulation experiments have been performed on Tore Supra. A large jump (a factor of 8) in the heat diffusivity has been clearly identified at the ECRH power deposition layer. The amplitude and phase of several harmonics of the Fourier transform of the modulated temperature, as well as the time evolution of the modulated temperature have been reproduced by the analytical solution. The jump is found to be much weaker at lower ECRH power (one gyrotron)

  7. Explicit finite-difference solution of two-dimensional solute transport with periodic flow in homogenous porous media

    Directory of Open Access Journals (Sweden)

    Djordjevich Alexandar

    2017-12-01

    Full Text Available The two-dimensional advection-diffusion equation with variable coefficients is solved by the explicit finitedifference method for the transport of solutes through a homogenous two-dimensional domain that is finite and porous. Retardation by adsorption, periodic seepage velocity, and a dispersion coefficient proportional to this velocity are permitted. The transport is from a pulse-type point source (that ceases after a period of activity. Included are the firstorder decay and zero-order production parameters proportional to the seepage velocity, and periodic boundary conditions at the origin and at the end of the domain. Results agree well with analytical solutions that were reported in the literature for special cases. It is shown that the solute concentration profile is influenced strongly by periodic velocity fluctuations. Solutions for a variety of combinations of unsteadiness of the coefficients in the advection-diffusion equation are obtainable as particular cases of the one demonstrated here. This further attests to the effectiveness of the explicit finite difference method for solving two-dimensional advection-diffusion equation with variable coefficients in finite media, which is especially important when arbitrary initial and boundary conditions are required.

  8. Semianalytical solutions for contaminant transport under variable velocity field in a coastal aquifer

    Science.gov (United States)

    Koohbor, Behshad; Fahs, Marwan; Ataie-Ashtiani, Behzad; Simmons, Craig T.; Younes, Anis

    2018-05-01

    Existing closed-form solutions of contaminant transport problems are limited by the mathematically convenient assumption of uniform flow. These solutions cannot be used to investigate contaminant transport in coastal aquifers where seawater intrusion induces a variable velocity field. An adaptation of the Fourier-Galerkin method is introduced to obtain semi-analytical solutions for contaminant transport in a confined coastal aquifer in which the saltwater wedge is in equilibrium with a freshwater discharge flow. Two scenarios dealing with contaminant leakage from the aquifer top surface and contaminant migration from a source at the landward boundary are considered. Robust implementation of the Fourier-Galerkin method is developed to efficiently solve the coupled flow, salt and contaminant transport equations. Various illustrative examples are generated and the semi-analytical solutions are compared against an in-house numerical code. The Fourier series are used to evaluate relevant metrics characterizing contaminant transport such as the discharge flux to the sea, amount of contaminant persisting in the groundwater and solute flux from the source. These metrics represent quantitative data for numerical code validation and are relevant to understand the effect of seawater intrusion on contaminant transport. It is observed that, for the surface contamination scenario, seawater intrusion limits the spread of the contaminant but intensifies the contaminant discharge to the sea. For the landward contamination scenario, moderate seawater intrusion affects only the spatial distribution of the contaminant plume while extreme seawater intrusion can increase the contaminant discharge to the sea. The developed semi-analytical solution presents an efficient tool for the verification of numerical models. It provides a clear interpretation of the contaminant transport processes in coastal aquifers subject to seawater intrusion. For practical usage in further studies, the full

  9. Water flow and solute transport using environmental isotopes and modeling

    International Nuclear Information System (INIS)

    Hussein, M.F.

    2001-01-01

    The deep unsaturated zone may be a useful hydrological archive in desert environments characterized by scant or sporadic rainfall and slow percolation of rainwater over decades or even centuries. This moisture archive provides a useful way to distinguish the net downward flow of recharge water, whereas the isotopic composition and concentration of the conservative solutes of the preserved moisture could be used to reconstruct the history of recharge under the prevailing deficient water balance. The major advantage of such coupled approach is to obtain independent estimates of groundwater recharge rates which are normally difficult to evaluate using the hydrological methods applied in the temperate zones. The study was conducted in the Shiekh-Zoweid/Raffa area in the northeastern coastal strip of Sinai Peninsula. Bore-holes were dry-drilled in a line perpendicular to the sea shoreline (using an 8-inch diameter hand-operated rotary rig) for the unsaturated sediment collection from successive 0.5m thick layers down to a depth of 20m. Samples were investigated for the moisture contents and the chemical and isotope composition of this moisture was determined. Physical parameters were also assessed including porosity and volumetric moisture content. Chloride mass-balance was used to calculate recharge rates through the unsaturated zone by predicting the position of the 1963-Tritium peak in the unsaturated column. Analysis of moisture, chloride and deuterium profiles showed three principle peaks (along with minor ones) in Karafin site indicating few major recharge events that have taken place during the last few decades. Adjustment of these episodes has also been attempted using two historical major rainfall events (known from nearby meteorological stations). Application of the methodology in water resources management in arid regions is discussed. (author)

  10. The "Common Solutions" Strategy of the Experiment Support group at CERN for the LHC Experiments

    CERN Document Server

    Girone, M; Barreiro Megino, F H; Campana, S; Cinquilli, M; Di Girolamo, A; Dimou, M; Giordano, D; Karavakis, E; Kenyon, M J; Kokozkiewicz, L; Lanciotti, E; Litmaath, M; Magini, N; Negri, G; Roiser, S; Saiz, P; Saiz Santos, M D; Schovancova, J; Sciabà, A; Spiga, D; Trentadue, R; Tuckett, D; Valassi, A; Van der Ster, D C; Shiers, J D

    2012-01-01

    After two years of LHC data taking, processing and analysis and with numerous changes in computing technology, a number of aspects of the experiments' computing, as well as WLCG deployment and operations, need to evolve. As part of the activities of the Experiment Support group in CERN's IT department, and reinforced by effort from the EGI-InSPIRE project, we present work aimed at common solutions across all LHC experiments. Such solutions allow us not only to optimize development manpower but also offer lower long-term maintenance and support costs. The main areas cover Distributed Data Management, Data Analysis, Monitoring and the LCG Persistency Framework. Specific tools have been developed including the HammerCloud framework, automated services for data placement, data cleaning and data integrity (such as the data popularity service for CMS, the common Victor cleaning agent for ATLAS and CMS and tools for catalogue/storage consistency), the Dashboard Monitoring framework (job monitoring, data management m...

  11. Bacterial transport in heterogeneous porous media: Observations from laboratory experiments

    Science.gov (United States)

    Silliman, S. E.; Dunlap, R.; Fletcher, M.; Schneegurt, M. A.

    2001-11-01

    Transport of bacteria through heterogeneous porous media was investigated in small-scale columns packed with sand and in a tank designed to allow the hydraulic conductivity to vary as a two-dimensional, lognormally distributed, second-order stationary, exponentially correlated random field. The bacteria were Pseudomonas ftuorescens R8, a strain demonstrating appreciable attachment to surfaces, and strain Ml, a transposon mutant of strain R8 with reduced attachment ability. In bench top, sand-filled columns, transport was determined by measuring intensity of fluorescence of stained cells in the effluent or by measuring radiolabeled cells that were retained in the sand columns. Results demonstrated that strain Ml was transported more efficiently than strain R8 through columns packed with either a homogeneous silica sand or a more heterogeneous sand with iron oxide coatings. Two experiments conducted in the tank involved monitoring transport of bacteria to wells via sampling from wells and sample ports in the tank. Bacterial numbers were determined by direct plate count. At the end of the first experiment, the distribution of the bacteria in the sediment was determined by destructive sampling and plating. The two experiments produced bacterial breakthrough curves that were quite similar even though the similarity between the two porous media was limited to first- and second-order statistical moments. This result appears consistent with the concept of large-scale, average behavior such as has been observed for the transport of conservative chemical tracers. The transported bacteria arrived simultaneously with a conservative chemical tracer (although at significantly lower normalized concentration than the tracer). However, the bacterial breakthrough curves showed significant late time tailing. The concentrations of bacteria attached to the sediment surfaces showed considerably more spatial variation than did the concentrations of bacteria in the fluid phase. This

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

    International Nuclear Information System (INIS)

    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

  13. 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.

  14. Analytical solutions of a fractional diffusion-advection equation for solar cosmic-ray transport

    International Nuclear Information System (INIS)

    Litvinenko, Yuri E.; Effenberger, Frederic

    2014-01-01

    Motivated by recent applications of superdiffusive transport models to shock-accelerated particle distributions in the heliosphere, we analytically solve a one-dimensional fractional diffusion-advection equation for the particle density. We derive an exact Fourier transform solution, simplify it in a weak diffusion approximation, and compare the new solution with previously available analytical results and with a semi-numerical solution based on a Fourier series expansion. We apply the results to the problem of describing the transport of energetic particles, accelerated at a traveling heliospheric shock. Our analysis shows that significant errors may result from assuming an infinite initial distance between the shock and the observer. We argue that the shock travel time should be a parameter of a realistic superdiffusive transport model.

  15. Numerical modelling of coupled fluid, heat, and solute transport in deformable fractured rock

    International Nuclear Information System (INIS)

    Chan, T.; Reid, J.A.K.

    1987-01-01

    This paper reports on a three-dimensional (3D) finite-element code, MOTIF (model of transport in fractured/porous media), developed to model the coupled processes of groundwater flow, heat transport, brine transport, and one-species radionuclide transport in geological media. Three types of elements are available: a 3D continuum element, a planar fracture element that can be oriented in any arbitrary direction in 3D space or pipe flow in 3D space, and a line element for simulating fracture flow in 2D space or pipe flow in 3D space. As a quality-assurance measure, the MOTIF code was verified by comparison of its results with analytical solutions and other published numerical solutions

  16. Fluctuation theorem for channel-facilitated membrane transport of interacting and noninteracting solutes.

    Science.gov (United States)

    Berezhkovskii, Alexander M; Bezrukov, Sergey M

    2008-05-15

    In this paper, we discuss the fluctuation theorem for channel-facilitated transport of solutes through a membrane separating two reservoirs. The transport is characterized by the probability, P(n)(t), that n solute particles have been transported from one reservoir to the other in time t. The fluctuation theorem establishes a relation between P(n)(t) and P-(n)(t): The ratio P(n)(t)/P-(n)(t) is independent of time and equal to exp(nbetaA), where betaA is the affinity measured in the thermal energy units. We show that the same fluctuation theorem is true for both single- and multichannel transport of noninteracting particles and particles which strongly repel each other.

  17. Identification of key target markets for intermodal freight transport solutions in South Africa

    Directory of Open Access Journals (Sweden)

    Joubert van Eeden

    2010-11-01

    Full Text Available The Accelerated and Shared Growth Initiative for South Africa (AsgiSA identified South Africa's freight logistics challenges as among the key binding constraints on the country's growth aspirations. The research presented here points to the structural imbalance between road and rail freight transport as one of the key contributors to this state of affairs. Most long-distance corridor transport has been captured by road. However, long-distance transport is a market segment that is very suitable for intermodal transportation : rail is utilised for the high-density, long-distance component and road for the feeder and distribution services at the corridor end points. A market segmentation approach is developed to identify the corridors and industries that are natural candidates for such solutions, thereby paving the way for role-players and stakeholders to initiate a dialogue on the development of appropriate solutions.

  18. Modeling of water and solute transport under variably saturated conditions: state of the art

    International Nuclear Information System (INIS)

    Lappala, E.G.

    1980-01-01

    This paper reviews the equations used in deterministic models of mass and energy transport in variably saturated porous media. Analytic, quasi-analytic, and numerical solution methods to the nonlinear forms of transport equations are discussed with respect to their advantages and limitations. The factors that influence the selection of a modeling method are discussed in this paper; they include the following: (1) the degree of coupling required among the equations describing the transport of liquids, gases, solutes, and energy; (2) the inclusion of an advection term in the equations; (3) the existence of sharp fronts; (4) the degree of nonlinearity and hysteresis in the transport coefficients and boundary conditions; (5) the existence of complex boundaries; and (6) the availability and reliability of data required by the models

  19. Criticality experiments with annular cylinders containing plutonium solutions; Experiences de criticite sur des cylindres annulaires contenant des solutions de plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Molbert, M; Sauve, A; Houelle, M; Deilgat, E [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    The criticality station of Dijon involves three cells, shielded by concrete walls of 1.46 meter thickness. Those cells are designed to contain the criticality experiment apparatus. The engineering building is also involving: one chemical laboratory where plutonium solutions are prepared, one analysis laboratory, several activated solutions storages, several control rooms, One cell contains the B system, which is designed to study: annular cylindrical geometries, slab of 10 cm thickness, interaction between annular cylinders. This report includes the first results given by experiments on annular cylinders defined by their own geometry (outer and inner diameter of ring containing plutonium solutions). Those results have been plotted in curves, for several concentrations and for different reflection conditions (outer or inner light water reflector, cadmium screen), H{sub c} and M{sub c} = f (c) (where H{sub c} is the critical height of solution, M{sub c} is the critical mass, c is the plutonium concentration: 42,3 g/lsolutions. - an insulated annular cylinder 500 x 200: incomplete results are published the experiments on this cylinder being unfinished to the date of this present report publication. On this miscellaneous results, we have following informations know: - Screen effect of light water in central hole. Strengthened effect by cadmium foil on the inside wall. - Normalized interaction curves ( {alpha}*H{sub c}/H{sub c{infinity}} ) versus the distance between the two vessels, where H{sub c{infinity}} critical height of an insulated cylinder, shows that: 1) In light water, two cylinders set aside from 15 cm, can be considers like separated. 2) For some configurations, {alpha} vary

  20. Container transport direct call – logistic solution to container transport via Estonia

    Directory of Open Access Journals (Sweden)

    A. Tolli

    2007-12-01

    Full Text Available Container transport in the world grows up to 12 % every year. Chinese container transport contributes majority of container flows in international container transport. Many world seaports compete for Chinese container flows and make eff orts to get investments and direct calls from China to their ports. Estonia has a possibility to decrease its large dependence and risks due to the transit of oil and oil products and coal with the help of container flows from China. In addition to a favorable geographical location Estonia has several other important arguments, like suffi cient land in the harbours for developing a container terminal to launch extensive container transport transit from China. Port of St. Petersburg, container transport port closest to Estonia by the Baltic Sea, is overloaded. Estonia can compete for container flows directed to Moscow, Nizhniy Novgorod, Kazan and Kaluga. Construction of an international high-tech container terminal in Port of Tallinn serves as one important precondition for directing Russian transit container flows through Estonia. Such a container terminal could service also larger vessels and container flows from China. Container lines and container terminals operating as alliances are jointly able to substantially increase container flows through countries.

  1. Spatial model of convective solute transport in brain extracellular space does not support a "glymphatic" mechanism.

    Science.gov (United States)

    Jin, Byung-Ju; Smith, Alex J; Verkman, Alan S

    2016-12-01

    A "glymphatic system," which involves convective fluid transport from para-arterial to paravenous cerebrospinal fluid through brain extracellular space (ECS), has been proposed to account for solute clearance in brain, and aquaporin-4 water channels in astrocyte endfeet may have a role in this process. Here, we investigate the major predictions of the glymphatic mechanism by modeling diffusive and convective transport in brain ECS and by solving the Navier-Stokes and convection-diffusion equations, using realistic ECS geometry for short-range transport between para-arterial and paravenous spaces. Major model parameters include para-arterial and paravenous pressures, ECS volume fraction, solute diffusion coefficient, and astrocyte foot-process water permeability. The model predicts solute accumulation and clearance from the ECS after a step change in solute concentration in para-arterial fluid. The principal and robust conclusions of the model are as follows: (a) significant convective transport requires a sustained pressure difference of several mmHg between the para-arterial and paravenous fluid and is not affected by pulsatile pressure fluctuations; (b) astrocyte endfoot water permeability does not substantially alter the rate of convective transport in ECS as the resistance to flow across endfeet is far greater than in the gaps surrounding them; and (c) diffusion (without convection) in the ECS is adequate to account for experimental transport studies in brain parenchyma. Therefore, our modeling results do not support a physiologically important role for local parenchymal convective flow in solute transport through brain ECS. © 2016 Jin et al.

  2. Perturbative Heat Transport Experiments on TJ-II

    International Nuclear Information System (INIS)

    Eguilor, S.; Castejon, F.; Luna, E. de la; Cappa, A.; Likin, K.; Fernandez, A.; Tj-II, T.

    2002-01-01

    Heat wave experiments are performed on TJ-II stellarator plasmas to estimate both heat diffusivity and power deposition profiles. High frequency ECRH modulation experiments are used to obtain the power deposition profiles, which is observed to be wider and duller than estimated by tracing techniques. The causes of this difference are discussed in the paper. Fourier analysis techniques are used to estimate the heat diffusivity in low frequency ECRH modulation experiments. This include the power deposition profile as a new ingredient. ECHR switch on/off experiments are exploited to obtain power deposition and heat diffusivities profile. Those quantities are compared with the obtained by modulation experiments and transport analysis, showing a good agreement. (Author) 18 refs

  3. Perturbative Heat Transport Experiments on TJ-II

    Energy Technology Data Exchange (ETDEWEB)

    Eguilor, S.; Castejon, F.; Luna, E. de la; Cappa, A.; Likin, K.; Fernandez, A.; Tj-II, T.

    2002-07-01

    Heat wave experiments are performed on TJ-II stellarator plasmas to estimate both heat diffusivity and power deposition profiles. High frequency ECRH modulation experiments are used to obtain the power deposition profiles, which is observed to be wider and duller than estimated by tracing techniques. The causes of this difference are discussed in the paper. Fourier analysis techniques are used to estimate the heat diffusivity in low frequency ECRH modulation experiments. This include the power deposition profile as a new ingredient. ECHR switch on/off experiments are exploited to obtain power deposition and heat diffusivities profile. Those quantities are compared with the obtained by modulation experiments and transport analysis, showing a good agreement. (Author) 18 refs.

  4. Experience with control valve cavitation problems and their solutions

    International Nuclear Information System (INIS)

    Ozol, J.

    1988-01-01

    Pressure reduction in control valves can induce cavitation, which has three effects on the control valve. Firstly, it modifies or changes the hydraulic performance of the control valve. Since control valves are designed for noncavitating conditions, the result is usually reduced stability of the control valve or, in extreme cavitating conditions known as supercavitation, the valve may limit the flow rate and thus be undersized. Secondly, cavitation can cause material damage to valve parts, trim, or valve body, or erodes downstream piping; consequently, the valve or piping leaks. Thirdly, cavitation causes noise and vibration, which may cause major damage or destruction to equipment such as valve positioners, actuators, pipe supports and sometimes to other downstream valves. The purpose of this paper is twofold: (1) It describes the I.S.A. valve sizing equations and how they relate to cavitation. (2) It describes experiences with these three problems, and discusses corrective actions and practical approaches to their solution. This paper discusses thirteen cavitation experiences

  5. TRACKING AND TRACING SOLUTION FOR DANGEROUS GOODS CARRIED BY INTERMODAL TRANSPORT

    Directory of Open Access Journals (Sweden)

    Marek Kvet

    2014-03-01

    Full Text Available This paper deals with the problem of designing a complex tracking and tracing solution for dangerous goods transportation with the support of modern information technologies. This research activity presents a part of the “ChemLogTT” [2] project solved at the University of Žilina. The main goal of our contribution is to present basic conception of a complex developed software tool for monitoring and analyzing mentioned dangerous goods transportation.

  6. Ion Transport in Organic Electrolyte Solution through the Pore Channels of Anodic Nanoporous Alumina Membranes

    International Nuclear Information System (INIS)

    Fukutsuka, Tomokazu; Koyamada, Kohei; Maruyama, Shohei; Miyazaki, Kohei; Abe, Takeshi

    2016-01-01

    Highlights: • Ion transport in organic electrolyte solution in macro- and meso-pores was focused. • Anodic nanoporous alumina membrane was used as a porous material. • The specific ion conductivities drastically decreased in macro- and meso-pores. - Abstract: For the development of high energy density lithium-ion batteries with the high rate performance, the enhancement of the ion transport in the electrolyte solutions impregnated in the porous electrodes is a key. To study the ion transport in porous electrodes, anodic nanoporous alumina (APA) self-standing membranes with macro- or meso-pores were used as model porous materials. These membranes had nearly spherical pore channels of discrete 20–68 nm in diameters. By using the geometric shape of the pores, we attempted to evaluate the specific ion conductivities of the organic electrolyte solution dissolving lithium salt simply. AC impedance spectroscopy measurement of a four-electrode cell with membranes showed one depressed semi-circle in the Nyquist plots and this semi-circle can be assigned as the ion transport resistance in the pores. The specific ion conductivities evaluated from the ion transport resistances and the geometric parameters showed very small values, even in the macro-pores, as compared with that of the bulk electrolyte solution.

  7. The simulation of solute transport: An approach free of numerical dispersion

    International Nuclear Information System (INIS)

    Carrera, J.; Melloni, G.

    1987-01-01

    The applicability of most algorithms for simulation of solute transport is limited either by instability or by numerical dispersion, as seen by a review of existing methods. A new approach is proposed that is free of these two problems. The method is based on the mixed Eulerian-Lagrangian formulation of the mass-transport problem, thus ensuring stability. Advection is simulated by a variation of reverse-particle tracking that avoids the accumulation of interpolation errors, thus preventing numerical dispersion. The algorithm has been implemented in a one-dimensional code. Excellent results are obtained, in comparison with an analytical solution. 36 refs., 14 figs., 1 tab

  8. Verification of T2VOC using an analytical solution for VOC transport in vadose zone

    Energy Technology Data Exchange (ETDEWEB)

    Shan, C. [Lawrence Berkeley Laboratory, Berkeley, CA (United States)

    1995-03-01

    T2VOC represents an adaption of the STMVOC to the TOUGH2 environment. In may contaminated sites, transport of volatile organic chemicals (VOC) is a serious problem which can be simulated by T2VOC. To demonstrate the accuracy and robustness of the code, we chose a practical problem of VOC transport as the test case, conducted T2VOC simulations, and compared the results of T2VOC with those of an analytical solution. The agreements between T2VOC and the analytical solutions are excellent. In addition, the numerical results of T2VOC are less sensitive to grid size and time step to a certain extent.

  9. Bacterial Transport in Heterogeneous Porous Media: Laboratory and Field Experiments

    Science.gov (United States)

    Fuller, M. E.

    2001-12-01

    A fully instrumented research site for examining field-scale bacterial transport has been established on the eastern shore of Virginia. Studies employing intact sediment cores from the South Oyster site have been performed to examine the effects of physical and chemical heterogeneity, to derive transport parameters, and to aid in the selection of bacterial strains for use in field experiments. A variety of innovative methods for tracking bacteria were developed and evaluated under both laboratory and field conditions, providing the tools to detect target cell concentrations in groundwater down to effects of physical and chemical heterogeneity on field-scale bacterial transport. The results of this research not only contribute to the development of more effective bioremediation strategies, but also have implications for a better understanding of bacterial movement in the subsurface as it relates to public health microbiology and general microbial ecology.

  10. Flow and transport at the Las Cruces trench site: Experiment IIb

    International Nuclear Information System (INIS)

    Vinson, J.; Hills, R.G.; Wierenga, P.J.; Young, M.H.

    1997-07-01

    The US Nuclear Regulatory Commission (NRC) has been directed by Congress in the Low Level Waste Policy Act of 1980 to develop regulatory guidance and assist the individual states and compacts in siting and assessing future low level radioactive waste (LLW) disposal facilities. Three water flow and solute transport experiments were performed as part of a comprehensive field trench study near Las Cruces, New Mexico to test deterministic and stochastic models of vadose zone flow and transport. This report presents partial results from the third experiment (experiment IIb). Experiments IIa and b were conducted on the North side of the trench, on a plot 1.22 m wide by 12 m long, perpendicular to the trench. The area was drip irrigated during two time periods with water containing a variety of tracers. The advance of the water front during the two irrigation episodes was measured with tensiometers and neutron probes. Solute front positions were determined from soil solution sampling through suction samplers and from disturbed sampling. The results from experiment IIb show predominantly downward water movement through the layered unsaturated soil, as evidenced from neutron probe data and gravimetric sampling. Tritium plumes were only half as deep and half as wide as the water plumes at 310 days after the beginning of experiment IIb. Chromium, applied as Cr(VI), moved a readily as, and similar to tritium, but there was a loss of mass due to reduction of Cr(VI) to Cr(III). Chloride and nitrate, initially present at high concentrations in the soil solution, were displaced by the low concentration irrigation water, resulting in chloride and nitrate concentration distributions that looked like negative images of the tritium distributions. The extensive data presented should serve well as a data base for model testing

  11. Flow and transport at the Las Cruces trench site: Experiment IIb

    Energy Technology Data Exchange (ETDEWEB)

    Vinson, J.; Hills, R.G. [New Mexico State Univ., Las Cruces, NM (United States); Wierenga, P.J.; Young, M.H. [Arizona Univ., Tucson, AZ (United States). Dept. of Soil and Water Science

    1997-07-01

    The US Nuclear Regulatory Commission (NRC) has been directed by Congress in the Low Level Waste Policy Act of 1980 to develop regulatory guidance and assist the individual states and compacts in siting and assessing future low level radioactive waste (LLW) disposal facilities. Three water flow and solute transport experiments were performed as part of a comprehensive field trench study near Las Cruces, New Mexico to test deterministic and stochastic models of vadose zone flow and transport. This report presents partial results from the third experiment (experiment IIb). Experiments IIa and b were conducted on the North side of the trench, on a plot 1.22 m wide by 12 m long, perpendicular to the trench. The area was drip irrigated during two time periods with water containing a variety of tracers. The advance of the water front during the two irrigation episodes was measured with tensiometers and neutron probes. Solute front positions were determined from soil solution sampling through suction samplers and from disturbed sampling. The results from experiment IIb show predominantly downward water movement through the layered unsaturated soil, as evidenced from neutron probe data and gravimetric sampling. Tritium plumes were only half as deep and half as wide as the water plumes at 310 days after the beginning of experiment IIb. Chromium, applied as Cr(VI), moved a readily as, and similar to tritium, but there was a loss of mass due to reduction of Cr(VI) to Cr(III). Chloride and nitrate, initially present at high concentrations in the soil solution, were displaced by the low concentration irrigation water, resulting in chloride and nitrate concentration distributions that looked like negative images of the tritium distributions. The extensive data presented should serve well as a data base for model testing.

  12. Electrodriven selective transport of Cs+ using chlorinated cobalt dicarbollide in polymer inclusion membrane: a novel approach for cesium removal from simulated nuclear waste solution.

    Science.gov (United States)

    Chaudhury, Sanhita; Bhattacharyya, Arunasis; Goswami, Asok

    2014-11-04

    The work describes a novel and cleaner approach of electrodriven selective transport of Cs from simulated nuclear waste solutions through cellulose tri acetate (CTA)/poly vinyl chloride (PVC) based polymer inclusion membrane. The electrodriven cation transport together with the use of highly Cs+ selective hexachlorinated derivative of cobalt bis dicarbollide, allows to achieve selective separation of Cs+ from high concentration of Na+ and other fission products in nuclear waste solutions. The transport selectivity has been studied using radiotracer technique as well as atomic emission spectroscopic technique. Transport studies using CTA based membrane have been carried out from neutral solution as well as 0.4 M HNO3, while that with PVC based membrane has been carried out from 3 M HNO3. High decontamination factor for Cs+ over Na+ has been obtained in all the cases. Experiment with simulated high level waste solution shows selective transport of Cs+ from most of other fission products also. Significantly fast Cs+ transport rate along with high selectivity is an interesting feature observed in this membrane. The current efficiency for Cs+ transport has been found to be ∼100%. The promising results show the possibility of using this kind of electrodriven membrane transport methods for nuclear waste treatment.

  13. Limit Theorems and Their Relation to Solute Transport in Simulated Fractured Media

    Science.gov (United States)

    Reeves, D. M.; Benson, D. A.; Meerschaert, M. M.

    2003-12-01

    Solute particles that travel through fracture networks are subject to wide velocity variations along a restricted set of directions. This may result in super-Fickian dispersion along a few primary scaling directions. The fractional advection-dispersion equation (FADE), a modification of the original advection-dispersion equation in which a fractional derivative replaces the integer-order dispersion term, has the ability to model rapid, non-Gaussian solute transport. The FADE assumes that solute particle motions converge to either α -stable or operator stable densities, which are modeled by spatial fractional derivatives. In multiple dimensions, the multi-fractional dispersion derivative dictates the order and weight of differentiation in all directions, which correspond to the statistics of large particle motions in all directions. This study numerically investigates the presence of super- Fickian solute transport through simulated two-dimensional fracture networks. An ensemble of networks is gen

  14. Analytical solution of electrohydrodynamic flow and transport in rectangular channels: inclusion of double layer effects

    KAUST Repository

    Joekar-Niasar, V.

    2013-01-25

    Upscaling electroosmosis in porous media is a challenge due to the complexity and scale-dependent nonlinearities of this coupled phenomenon. "Pore-network modeling" for upscaling electroosmosis from pore scale to Darcy scale can be considered as a promising approach. However, this method requires analytical solutions for flow and transport at pore scale. This study concentrates on the development of analytical solutions of flow and transport in a single rectangular channel under combined effects of electrohydrodynamic forces. These relations will be used in future works for pore-network modeling. The analytical solutions are valid for all regimes of overlapping electrical double layers and have the potential to be extended to nonlinear Boltzmann distribution. The innovative aspects of this study are (a) contribution of overlapping of electrical double layers to the Stokes flow as well as Nernst-Planck transport has been carefully included in the analytical solutions. (b) All important transport mechanisms including advection, diffusion, and electromigration have been included in the analytical solutions. (c) Fully algebraic relations developed in this study can be easily employed to upscale electroosmosis to Darcy scale using pore-network modeling. © 2013 Springer Science+Business Media Dordrecht.

  15. Analytical solution of electrohydrodynamic flow and transport in rectangular channels: inclusion of double layer effects

    KAUST Repository

    Joekar-Niasar, V.; Schotting, R.; Leijnse, A.

    2013-01-01

    Upscaling electroosmosis in porous media is a challenge due to the complexity and scale-dependent nonlinearities of this coupled phenomenon. "Pore-network modeling" for upscaling electroosmosis from pore scale to Darcy scale can be considered as a promising approach. However, this method requires analytical solutions for flow and transport at pore scale. This study concentrates on the development of analytical solutions of flow and transport in a single rectangular channel under combined effects of electrohydrodynamic forces. These relations will be used in future works for pore-network modeling. The analytical solutions are valid for all regimes of overlapping electrical double layers and have the potential to be extended to nonlinear Boltzmann distribution. The innovative aspects of this study are (a) contribution of overlapping of electrical double layers to the Stokes flow as well as Nernst-Planck transport has been carefully included in the analytical solutions. (b) All important transport mechanisms including advection, diffusion, and electromigration have been included in the analytical solutions. (c) Fully algebraic relations developed in this study can be easily employed to upscale electroosmosis to Darcy scale using pore-network modeling. © 2013 Springer Science+Business Media Dordrecht.

  16. High current transport experiment for heavy ion inertial fusion

    Directory of Open Access Journals (Sweden)

    L. R. Prost

    2005-02-01

    Full Text Available The High Current Experiment at Lawrence Berkeley National Laboratory is part of the U.S. program to explore heavy-ion beam transport at a scale representative of the low-energy end of an induction linac driver for fusion energy production. The primary mission of this experiment is to investigate aperture fill factors acceptable for the transport of space-charge-dominated heavy-ion beams at high intensity (line charge density ∼0.2  μC/m over long pulse durations (4  μs in alternating gradient focusing lattices of electrostatic or magnetic quadrupoles. This experiment is testing transport issues resulting from nonlinear space-charge effects and collective modes, beam centroid alignment and steering, envelope matching, image charges and focusing field nonlinearities, halo, and electron and gas cloud effects. We present the results for a coasting 1 MeV K^{+} ion beam transported through ten electrostatic quadrupoles. The measurements cover two different fill factor studies (60% and 80% of the clear aperture radius for which the transverse phase space of the beam was characterized in detail, along with beam energy measurements and the first halo measurements. Electrostatic quadrupole transport at high beam fill factor (≈80% is achieved with acceptable emittance growth and beam loss, even though the initial beam distribution is not ideal (but the emittance is low nor in thermal equilibrium. We achieved good envelope control, and rematching may only be needed every ten lattice periods (at 80% fill factor in a longer lattice of similar design. We also show that understanding and controlling the time dependence of the envelope parameters is critical to achieving high fill factors, notably because of the injector and matching section dynamics.

  17. Decentralized cogeneration - A solution for Romania? RAEF experience

    International Nuclear Information System (INIS)

    Binig, Alexandru-Valeriu

    2004-01-01

    deficit should be covered using indigenous power generation sources. One could conclude, correlated with the previous discussion on financing investment, that most of the private capital is expected in the power and heat generation sector. New injection points might necessitate network reinforcement (implying additional costs and delays), may have to pass a complicated and lengthy authorizations process, etc. In conclusion, realisation of 'greenfield' large projects is likely to be cumbersome and delayed due mainly to issues related to connection to the grid. But also fuel supply issues, cooling water access, impact on communities, add to the serious siting problems for new greenfield power generation projects. A psychological impact on private investor's appetite is also given by the continuation of erection of Cernavoda 2, (3?) nuclear units, as these are modern, safe, and optimal at dispatching. In conclusion, in Romania, at present, one cannot identify large private power generation projects in advanced development phase. A solution could be decentralized power generation. Combined with covering a heat demand, it leads to distributed cogeneration. It is an EU and worldwide trend. The above, combined with the overall analysis of the experience in Romania and worldwide allow drawing the following conclusions: - Decentralised generation (cogeneration) is a solution to be considered for Romania and for the region; - The national energy strategy must consider it; - Resources should be allocated to it (not necessarily financial), thus contributing to sustainable development; - It must be promoted by appropriate legislative, regulatory fiscal, etc framework; - Periodic exchange of experience among different actors is decisive for avoiding wasting resources; - this is mainly the purpose of the present article; - Private initiative is the main driver and must be encouraged for promoting efficiency and sustainability; - The solution chosen yields better risk management while

  18. Solute transport along a single fracture in a porous rock: a simple analytical solution and its extension for modeling velocity dispersion

    Science.gov (United States)

    Liu, Longcheng; Neretnieks, Ivars; Shahkarami, Pirouz; Meng, Shuo; Moreno, Luis

    2018-02-01

    A simple and robust solution is developed for the problem of solute transport along a single fracture in a porous rock. The solution is referred to as the solution to the single-flow-path model and takes the form of a convolution of two functions. The first function is the probability density function of residence-time distribution of a conservative solute in the fracture-only system as if the rock matrix is impermeable. The second function is the response of the fracture-matrix system to the input source when Fickian-type dispersion is completely neglected; thus, the effects of Fickian-type dispersion and matrix diffusion have been decoupled. It is also found that the solution can be understood in a way in line with the concept of velocity dispersion in fractured rocks. The solution is therefore extended into more general cases to also account for velocity variation between the channels. This leads to a development of the multi-channel model followed by detailed statistical descriptions of channel properties and sensitivity analysis of the model upon changes in the model key parameters. The simulation results obtained by the multi-channel model in this study fairly well agree with what is often observed in field experiments—i.e. the unchanged Peclet number with distance, which cannot be predicted by the classical advection-dispersion equation. In light of the findings from the aforementioned analysis, it is suggested that forced-gradient experiments can result in considerably different estimates of dispersivity compared to what can be found in natural-gradient systems for typical channel widths.

  19. Electron effects in the Neutralized Transport Experiment (NTX)

    Energy Technology Data Exchange (ETDEWEB)

    Eylon, S. [Lawrence Berkeley National Laboratory (LBNL), MS47R 0112, 1 Cyclotron Road, Berkeley, CA 94720 (United States) and Heavy Ion Fusion Virtual National Laboratory, Cyclotron Road, CA 94720 (United States)]. E-mail: S_Eylon@lbl.gov; Henestroza, E. [Lawrence Berkeley National Laboratory (LBNL), MS47R 0112, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Heavy Ion Fusion Virtual National Laboratory, Cyclotron Road, CA 94720 (United States); Roy, P.K. [Lawrence Berkeley National Laboratory (LBNL), MS47R 0112, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Heavy Ion Fusion Virtual National Laboratory, Cyclotron Road, CA 94720 (United States); Yu, S.S. [Lawrence Berkeley National Laboratory (LBNL), MS47R 0112, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Heavy Ion Fusion Virtual National Laboratory, Cyclotron Road, CA 94720 (United States)

    2005-05-21

    The Neutralized Transport Experiment (NTX) at the Heavy Ion Fusion Virtual National Laboratory is exploring the performance of neutralized final focus systems for high-perveance heavy ion beams. To focus a high-intensity beam to a small spot requires a high-brightness beam. In the NTX experiment, a potassium ion beam of up to 400 keV and 80 mA is generated in a Pierce-type diode. At the diode exit, an aperture with variable opening provides the capability to vary the beam perveance. The beam is transported through four quadrupole magnets to a distance of 2.5 m. The beam can be neutralized and focused using a MEVVA plasma plug and a RF plasma source. We shall report on the measurement of the electron effects and the ways to mitigate the effects. Furthermore, we shall present the results of EGUN calculations consistent with the measurements effects of the electrons.

  20. Electron effects in the Neutralized Transport Experiment (NTX)

    International Nuclear Information System (INIS)

    Eylon, S.; Henestroza, E.; Roy, P.K.; Yu, S.S.

    2005-01-01

    The Neutralized Transport Experiment (NTX) at the Heavy Ion Fusion Virtual National Laboratory is exploring the performance of neutralized final focus systems for high-perveance heavy ion beams. To focus a high-intensity beam to a small spot requires a high-brightness beam. In the NTX experiment, a potassium ion beam of up to 400 keV and 80 mA is generated in a Pierce-type diode. At the diode exit, an aperture with variable opening provides the capability to vary the beam perveance. The beam is transported through four quadrupole magnets to a distance of 2.5 m. The beam can be neutralized and focused using a MEVVA plasma plug and a RF plasma source. We shall report on the measurement of the electron effects and the ways to mitigate the effects. Furthermore, we shall present the results of EGUN calculations consistent with the measurements effects of the electrons

  1. Electron effects in the Neutralized Transport Experiment (NTX)

    Science.gov (United States)

    Eylon, S.; Henestroza, E.; Roy, P. K.; Yu, S. S.

    2005-05-01

    The Neutralized Transport Experiment (NTX) at the Heavy Ion Fusion Virtual National Laboratory is exploring the performance of neutralized final focus systems for high-perveance heavy ion beams. To focus a high-intensity beam to a small spot requires a high-brightness beam. In the NTX experiment, a potassium ion beam of up to 400 keV and 80 mA is generated in a Pierce-type diode. At the diode exit, an aperture with variable opening provides the capability to vary the beam perveance. The beam is transported through four quadrupole magnets to a distance of 2.5 m. The beam can be neutralized and focused using a MEVVA plasma plug and a RF plasma source. We shall report on the measurement of the electron effects and the ways to mitigate the effects. Furthermore, we shall present the results of EGUN calculations consistent with the measurements effects of the electrons.

  2. Development and applications of the channel network model for simulations of flow and solute transport in fractured rock

    International Nuclear Information System (INIS)

    Gylling, B.

    1997-01-01

    The Channel Network model and its computer implementation, the code CHAN3D, for simulations of fluid flow and transport of solutes have been developed. The tool may be used for performance and safety assessments of deep lying repositories in fractured rocks for nuclear and other hazardous wastes, e.g. chemical wastes. It may also be used to simulate and interpret field experiments of flow and transport in large or small scale. Fluid flow and solute transport in fractured media are of interest in the performance assessment of a repository for hazardous waste, located at depth in crystalline rock, with potential release of solutes. Fluid flow in fractured rock is found to be very unevenly distributed due to the heterogeneity of the medium. The water will seek the easiest path, channels, under a prevailing pressure gradient. Solutes in the flowing water may be transported through preferential paths and migrate from the water in the fractures into the stagnant water in the rock matrix. There, sorbing solutes may be sorbed on the micro surfaces within the matrix. The diffusion into the matrix and the sorption process may significantly retard the transport of species and increase the time available for radionuclide decay. Channelling and matrix diffusion contribute to the dispersion of solutes in the water. Important for performance assessment is that channeling may cause a portion of the solutes to arrive much faster than the rest of the solutes. Simulations of field experiments at the Aespoe Hard Rock Laboratory using the Channel Network model have been performed. The application of the model to the site and the simulation results of the pumping and tracer tests are presented. The results show that the model is capable of describing the hydraulic gradient and of predicting flow rates and tracer transport obtained in the experiments. The data requirements for the Channel Network model have been investigated to determine which data are the most important for predictions

  3. Nonlocal neoclassical transport in tokamak and spherical torus experiments

    International Nuclear Information System (INIS)

    Wang, W. X.; Rewoldt, G.; Tang, W. M.; Hinton, F. L.; Manickam, J.; Zakharov, L. E.; White, R. B.; Kaye, S.

    2006-01-01

    Large ion orbits can produce nonlocal neoclassical effects on ion heat transport, the ambipolar radial electric field, and the bootstrap current in realistic toroidal plasmas. Using a global δf particle simulation, it is found that the conventional local, linear gradient-flux relation is broken for the ion thermal transport near the magnetic axis. With regard to the transport level, it is found that details of the ion temperature profile determine whether the transport is higher or lower when compared with the predictions of standard neoclassical theory. Particularly, this nonlocal feature is suggested to exist in the National Spherical Torus Experiment (NSTX) [M. Ono, S. M. Kaye, Y.-K. M. Peng et al., Nucl. Fusion 40, 557 (2000)], being consistent with NSTX experimental evidence. It is also shown that a large ion temperature gradient can increase the bootstrap current. When the plasma rotation is taken into account, the toroidal rotation gradient can drive an additional parallel flow for the ions and then additional bootstrap current, either positive or negative, depending on the gradient direction. Compared with the carbon radial force balance estimate for the neoclassical poloidal flow, our nonlocal simulation predicts a significantly deeper radial electric field well at the location of an internal transport barrier of an NSTX discharge

  4. Perturbative transport experiments in JET Advanced Tokamak plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Mantica, P.; Gorini, G.; Sozzi, C. [Istituto di Fisica del Plasma, EURATOM-ENEA-CNR Association, Milan (Italy); Imbeaux, F.; Sarazin, Y.; Garbet, X. [Association Euratom-CEA, St. Paul-lez-Durance Cedex (France); Kinsey, J. [Lehigh Univ., Bethlehem, Pennsylvania (United States); Budny, R. [Princeton Plasma Physics Lab, New Jersey (United States); Coffey, I.; Parail, V.; Walden, A. [Euratom/UKAEA Fusion Association, Abingdon, Oxon (United Kingdom); Dux, R. [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany); Garzotti, L. [Istituto Gas Ionizzati, Padova (Italy); Ingesson, C. [FOM-Instituut voor Plasmafysica, Nieuwegein (Netherlands); Kissick, M. [University of California, Los Angeles (United States)

    2003-07-01

    Perturbative transport experiments have been performed in JET Advanced Tokamak plasmas either in conditions of fully developed Internal Transport Barrier (ITB) or during a phase where an ITB was not observed. Transient peripheral cooling was induced by either Laser Ablation or Shallow Pellet Injection and the ensuing travelling cold pulse was used to probe the plasma transport in the electron and, for the first time, also in the ion channel. Cold pulses travelling through ITBs are observed to erode the ITB outer part, but, if the inner ITB portion survives, it strongly damps the propagating wave. The result is discussed in the context of proposed possible pictures for ITB formation. In the absence of an ITB, the cold pulse shows a fast propagation in the outer plasma half, which is consistent with a region of stiff transport, while in the inner half it slows down but shows the peculiar feature of amplitude growing while propagating. The data are powerful tests for the validation of theoretical transport models. (author)

  5. Interactions of solutes and streambed sediment: 1. An experimental analysis of cation and anion transport in a mountain stream

    Science.gov (United States)

    Bencala, Kenneth E.; Kennedy, Vance C.; Zellweger, Gary W.; Jackman, Alan P.; Avanzino, Ronald J.

    1984-01-01

    An experimental injection was performed to study the transport of stream water solutes under conditions of significant interaction with streambed sediments in a mountain pool-and-riffle stream. Experiments were conducted in Little Lost Man Creek, Humboldt County, California, in a period of low flow duringwhich only a part of the bank-full channel held active surface flow. The injection of chloride and several trace cations lasted 20 days. In this report we discuss the results of the first 24 hours of the injection and survey the results of the first 10 days. Solute-streambed interactions of two types were observed. First, the physical transport of the conservative tracer, chloride, was affected by intergravel flow and stagnant watt, zones created by the bed relief. Second, the transport of the cations (strontium, potassium, and lithium) was appreciably modified by sorption onto streambed sediment. In the stream the readily observable consequence of the solute-streambed interactions was an attenuation of the dissolved concentration of each of the tracers. The attenuation in the stream channel occurred concurrently with the storage of tracers in the streambed via both physical and chemical processes. All tracers were subsequently present in shallow wells dug several meters from the wetted part of the channel. Sediment samples collected approximately 3 weeks after the start of the injection contained increased concentrations of the injected cations.

  6. A spatially adaptive grid-refinement approach for the finite element solution of the even-parity Boltzmann transport equation

    International Nuclear Information System (INIS)

    Mirza, Anwar M.; Iqbal, Shaukat; Rahman, Faizur

    2007-01-01

    A spatially adaptive grid-refinement approach has been investigated to solve the even-parity Boltzmann transport equation. A residual based a posteriori error estimation scheme has been utilized for checking the approximate solutions for various finite element grids. The local particle balance has been considered as an error assessment criterion. To implement the adaptive approach, a computer program ADAFENT (adaptive finite elements for neutron transport) has been developed to solve the second order even-parity Boltzmann transport equation using K + variational principle for slab geometry. The program has a core K + module which employs Lagrange polynomials as spatial basis functions for the finite element formulation and Legendre polynomials for the directional dependence of the solution. The core module is called in by the adaptive grid generator to determine local gradients and residuals to explore the possibility of grid refinements in appropriate regions of the problem. The a posteriori error estimation scheme has been implemented in the outer grid refining iteration module. Numerical experiments indicate that local errors are large in regions where the flux gradients are large. A comparison of the spatially adaptive grid-refinement approach with that of uniform meshing approach for various benchmark cases confirms its superiority in greatly enhancing the accuracy of the solution without increasing the number of unknown coefficients. A reduction in the local errors of the order of 10 2 has been achieved using the new approach in some cases

  7. A spatially adaptive grid-refinement approach for the finite element solution of the even-parity Boltzmann transport equation

    Energy Technology Data Exchange (ETDEWEB)

    Mirza, Anwar M. [Department of Computer Science, National University of Computer and Emerging Sciences, NUCES-FAST, A.K. Brohi Road, H-11, Islamabad (Pakistan)], E-mail: anwar.m.mirza@gmail.com; Iqbal, Shaukat [Faculty of Computer Science and Engineering, Ghulam Ishaq Khan (GIK) Institute of Engineering Science and Technology, Topi-23460, Swabi (Pakistan)], E-mail: shaukat@giki.edu.pk; Rahman, Faizur [Department of Physics, Allama Iqbal Open University, H-8 Islamabad (Pakistan)

    2007-07-15

    A spatially adaptive grid-refinement approach has been investigated to solve the even-parity Boltzmann transport equation. A residual based a posteriori error estimation scheme has been utilized for checking the approximate solutions for various finite element grids. The local particle balance has been considered as an error assessment criterion. To implement the adaptive approach, a computer program ADAFENT (adaptive finite elements for neutron transport) has been developed to solve the second order even-parity Boltzmann transport equation using K{sup +} variational principle for slab geometry. The program has a core K{sup +} module which employs Lagrange polynomials as spatial basis functions for the finite element formulation and Legendre polynomials for the directional dependence of the solution. The core module is called in by the adaptive grid generator to determine local gradients and residuals to explore the possibility of grid refinements in appropriate regions of the problem. The a posteriori error estimation scheme has been implemented in the outer grid refining iteration module. Numerical experiments indicate that local errors are large in regions where the flux gradients are large. A comparison of the spatially adaptive grid-refinement approach with that of uniform meshing approach for various benchmark cases confirms its superiority in greatly enhancing the accuracy of the solution without increasing the number of unknown coefficients. A reduction in the local errors of the order of 10{sup 2} has been achieved using the new approach in some cases.

  8. Particle and solute migration in porous media. Modeling of simultaneous transport of clay particles and radionuclides in a salinity gradient

    International Nuclear Information System (INIS)

    Faure, M.H.

    1994-03-01

    Understanding the mechanisms which control the transient transport of particles and radionuclides in natural and artificial porous media is a key problem for the assessment of safety of radioactive waste disposals. An experimental study has been performed to characterize the clayey particle mobility in porous media: a laboratory- made column, packed with an unconsolidated sand bentonite (5% weight) sample, is flushed with a salt solution. An original method of salinity gradient allowed us to show and to quantify some typical behaviours of this system: threshold effects in the peptization of particles, creation of preferential pathways, formation of immobile water zones induce solute-transfer limitation. The mathematical modelling accounts for a phenomenological law, where the distribution of particles between the stagnant water zone and the porous medium is a function of sodium chloride concentration. This distribution function is associated with a radionuclide adsorption model, and is included in a convective dispersive transport model with stagnant water zones. It allowed us to simulate the particle and solute transport when the salt environment is modified. The complete model has been validated with experiments involving cesium, calcium and neptunium in a sodium chloride gradient. (author). refs., figs., tabs

  9. 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.

  10. Verification of Monte Carlo transport codes by activation experiments

    OpenAIRE

    Chetvertkova, Vera

    2013-01-01

    With the increasing energies and intensities of heavy-ion accelerator facilities, the problem of an excessive activation of the accelerator components caused by beam losses becomes more and more important. Numerical experiments using Monte Carlo transport codes are performed in order to assess the levels of activation. The heavy-ion versions of the codes were released approximately a decade ago, therefore the verification is needed to be sure that they give reasonable results. Present work is...

  11. Transcellular movement of hydroxyurea is mediated by specific solute carrier transporters

    Science.gov (United States)

    Walker, Aisha L.; Franke, Ryan M.; Sparreboom, Alex; Ware, Russell E.

    2015-01-01

    Objective Hydroxyurea has proven laboratory and clinical therapeutic benefits for sickle cell anemia (SCA) and other diseases, yet many questions remain regarding its in vivo pharmacokinetic and pharmacodynamic profiles. Previous reports suggest that hydroxyurea passively diffuses across cells, but its observed rapid absorption and distribution are more consistent with facilitated or active transport. We investigated the potential role of solute carrier (SLC) transporters in cellular uptake and accumulation of hydroxyurea. Materials and Methods Passive diffusion of hydroxyurea across cell membranes was determined using the parallel artificial membrane permeability assay. SLC transporter screens were conducted using in vitro intracellular drug accumulation and transcellular transport assays in cell lines and oocytes overexpressing SLC transporters. Gene expression of SLC transporters was measured by real-time PCR in human tissues and cell lines. Results Hydroxyurea had minimal diffusion across a lipid bilayer but was a substrate for 5 different SLC transporters belonging to the OCTN and OATP families of transporters and urea transporters A and B. Further characterization of hydroxyurea transport revealed that cellular uptake by OATP1B3 is time and temperature dependent and inhibited by known substrates of OATP1B3. Urea transporters A and B are expressed differentially in human tissues and erythroid cells, and transport hydroxyurea bidirectionally via facilitated diffusion. Conclusions These studies provide new insight into drug transport proteins that may be involved in the in vivo absorption, cellular distribution, and elimination of hydroxyurea. Elucidation of hydroxyurea transcellular movement should improve our understanding of its pharmacokinetics and pharmacodynamics, and may help explain some of the inter-patient drug variability observed in patients with SCA. PMID:21256917

  12. Quantifying the relative contributions of different solute carriers to aggregate substrate transport

    Science.gov (United States)

    Taslimifar, Mehdi; Oparija, Lalita; Verrey, Francois; Kurtcuoglu, Vartan; Olgac, Ufuk; Makrides, Victoria

    2017-01-01

    Determining the contributions of different transporter species to overall cellular transport is fundamental for understanding the physiological regulation of solutes. We calculated the relative activities of Solute Carrier (SLC) transporters using the Michaelis-Menten equation and global fitting to estimate the normalized maximum transport rate for each transporter (Vmax). Data input were the normalized measured uptake of the essential neutral amino acid (AA) L-leucine (Leu) from concentration-dependence assays performed using Xenopus laevis oocytes. Our methodology was verified by calculating Leu and L-phenylalanine (Phe) data in the presence of competitive substrates and/or inhibitors. Among 9 potentially expressed endogenous X. laevis oocyte Leu transporter species, activities of only the uniporters SLC43A2/LAT4 (and/or SLC43A1/LAT3) and the sodium symporter SLC6A19/B0AT1 were required to account for total uptake. Furthermore, Leu and Phe uptake by heterologously expressed human SLC6A14/ATB0,+ and SLC43A2/LAT4 was accurately calculated. This versatile systems biology approach is useful for analyses where the kinetics of each active protein species can be represented by the Hill equation. Furthermore, its applicable even in the absence of protein expression data. It could potentially be applied, for example, to quantify drug transporter activities in target cells to improve specificity. PMID:28091567

  13. Preliminary characterization of materials for a reactive transport model validation experiment

    International Nuclear Information System (INIS)

    Siegel, M.D.; Ward, D.B.; Cheng, W.C.; Bryant, C.; Chocas, C.S.; Reynolds, C.G.

    1993-01-01

    The geochemical properties of a porous sand and several tracers (Ni, Br, and Li) have been characterized for use in a caisson experiment designed to validate sorption models used in models of inactive transport. The surfaces of the sand grains have been examined by a combination of techniques including potentiometric titration, acid leaching, optical microscopy, and scanning electron microscopy with energy-dispersive spectroscopy. The surface studies indicate the presence of small amounts of carbonate, kaolinite and iron-oxyhydroxides. Adsorption of nickel, lithium and bromide by the sand was measured using batch techniques. Bromide was not sorbed by the sand. A linear (K d ) or an isotherm sorption model may adequately describe transport of Li; however, a model describing the changes of pH and the concentrations of other solution species as a function of time and position within the caisson and the concomitant effects on Ni sorption may be required for accurate predictions of nickel transport

  14. Test of the 'glymphatic' hypothesis demonstrates diffusive and aquaporin-4-independent solute transport in rodent brain parenchyma.

    Science.gov (United States)

    Smith, Alex J; Yao, Xiaoming; Dix, James A; Jin, Byung-Ju; Verkman, Alan S

    2017-08-21

    Transport of solutes through brain involves diffusion and convection. The importance of convective flow in the subarachnoid and paravascular spaces has long been recognized; a recently proposed 'glymphatic' clearance mechanism additionally suggests that aquaporin-4 (AQP4) water channels facilitate convective transport through brain parenchyma. Here, the major experimental underpinnings of the glymphatic mechanism were re-examined by measurements of solute movement in mouse brain following intracisternal or intraparenchymal solute injection. We found that: (i) transport of fluorescent dextrans in brain parenchyma depended on dextran size in a manner consistent with diffusive rather than convective transport; (ii) transport of dextrans in the parenchymal extracellular space, measured by 2-photon fluorescence recovery after photobleaching, was not affected just after cardiorespiratory arrest; and (iii) Aqp4 gene deletion did not impair transport of fluorescent solutes from sub-arachnoid space to brain in mice or rats. Our results do not support the proposed glymphatic mechanism of convective solute transport in brain parenchyma.

  15. Modeling variably saturated subsurface solute transport with MODFLOW-UZF and MT3DMS

    Science.gov (United States)

    Morway, Eric D.; Niswonger, Richard G.; Langevin, Christian D.; Bailey, Ryan T.; Healy, Richard W.

    2013-01-01

    The MT3DMS groundwater solute transport model was modified to simulate solute transport in the unsaturated zone by incorporating the unsaturated-zone flow (UZF1) package developed for MODFLOW. The modified MT3DMS code uses a volume-averaged approach in which Lagrangian-based UZF1 fluid fluxes and storage changes are mapped onto a fixed grid. Referred to as UZF-MT3DMS, the linked model was tested against published benchmarks solved analytically as well as against other published codes, most frequently the U.S. Geological Survey's Variably-Saturated Two-Dimensional Flow and Transport Model. Results from a suite of test cases demonstrate that the modified code accurately simulates solute advection, dispersion, and reaction in the unsaturated zone. Two- and three-dimensional simulations also were investigated to ensure unsaturated-saturated zone interaction was simulated correctly. Because the UZF1 solution is analytical, large-scale flow and transport investigations can be performed free from the computational and data burdens required by numerical solutions to Richards' equation. Results demonstrate that significant simulation runtime savings can be achieved with UZF-MT3DMS, an important development when hundreds or thousands of model runs are required during parameter estimation and uncertainty analysis. Three-dimensional variably saturated flow and transport simulations revealed UZF-MT3DMS to have runtimes that are less than one tenth of the time required by models that rely on Richards' equation. Given its accuracy and efficiency, and the wide-spread use of both MODFLOW and MT3DMS, the added capability of unsaturated-zone transport in this familiar modeling framework stands to benefit a broad user-ship.

  16. Radiolysis of Fricke solution: initial experiments with the pelletron facility

    International Nuclear Information System (INIS)

    Sharma, S.B.; Rao, B.S.M.

    1994-01-01

    Experimental details of heavy ion irradiation of aqueous solutions using the Nuclear Science Centre (NSC) pelletron facility and the initial results from the radiolysis of Fricke solution using oxygen-16 ions are reported. (author). 4 refs., 1 fig

  17. Multiphase flow experiments, mathematical modeling and numerical simulation of the water - gas - solute movement

    Science.gov (United States)

    Li, Y.; Ma, X.; Su, N.

    2013-12-01

    The movement of water and solute into and through the vadose zone is, in essence, an issue of immiscible displacement in pore-space network of a soil. Therefore, multiphase flow and transport in porous media, referring to three medium: air, water, and the solute, pose one of the largest unresolved challenges for porous medium fluid seepage. However, this phenomenon has always been largely neglected. It is expected that a reliable analysis model of the multi-phase flow in soil can truly reflect the process of natural movement about the infiltration, which is impossible to be observed directly. In such cases, geophysical applications of the nuclear magnetic resonance (NMR) provides the opportunity to measure the water movements into soils directly over a large scale from tiny pore to regional scale, accordingly enable it available both on the laboratory and on the field. In addition, the NMR provides useful information about the pore space properties. In this study, we proposed both laboratory and field experiments to measure the multi-phase flow parameters, together with optimize the model in computer programming based on the fractional partial differential equations (fPDE). In addition, we establish, for the first time, an infiltration model including solute flowing with water, which has huge influence on agriculture and soil environment pollution. Afterwards, with data collected from experiments, we simulate the model and analyze the spatial variability of parameters. Simulations are also conducted according to the model to evaluate the effects of airflow on water infiltration and other effects such as solute and absorption. It has significant meaning to oxygen irrigation aiming to higher crop yield, and shed more light into the dam slope stability. In summary, our framework is a first-time model added in solute to have a mathematic analysis with the fPDE and more instructive to agriculture activities.

  18. Solution of the neutron transport problem with anisotropic scattering in cylindrical geometry by the decomposition method

    International Nuclear Information System (INIS)

    Goncalves, G.A.; Bogado Leite, S.Q.; Vilhena, M.T. de

    2009-01-01

    An analytical solution has been obtained for the one-speed stationary neutron transport problem, in an infinitely long cylinder with anisotropic scattering by the decomposition method. Series expansions of the angular flux distribution are proposed in terms of suitably constructed functions, recursively obtainable from the isotropic solution, to take into account anisotropy. As for the isotropic problem, an accurate closed-form solution was chosen for the problem with internal source and constant incident radiation, obtained from an integral transformation technique and the F N method

  19. Numerical Solution of the Electron Transport Equation in the Upper Atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Woods, Mark Christopher [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Holmes, Mark [Rensselaer Polytechnic Inst., Troy, NY (United States); Sailor, William C [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-07-01

    A new approach for solving the electron transport equation in the upper atmosphere is derived. The problem is a very stiff boundary value problem, and to obtain an accurate numerical solution, matrix factorizations are used to decouple the fast and slow modes. A stable finite difference method is applied to each mode. This solver is applied to a simplifieed problem for which an exact solution exists using various versions of the boundary conditions that might arise in a natural auroral display. The numerical and exact solutions are found to agree with each other to at least two significant digits.

  20. TCV experiments towards the development of a plasma exhaust solution

    Science.gov (United States)

    Reimerdes, H.; Duval, B. P.; Harrison, J. R.; Labit, B.; Lipschultz, B.; Lunt, T.; Theiler, C.; Tsui, C. K.; Verhaegh, K.; Vijvers, W. A. J.; Boedo, J. A.; Calabro, G.; Crisanti, F.; Innocente, P.; Maurizio, R.; Pericoli, V.; Sheikh, U.; Spolare, M.; Vianello, N.; the TCV Team; the EUROfusion MST1 Team

    2017-12-01

    Research towards a plasma exhaust solution for a fusion power plant aims at validating edge physics models, strengthening predictive capabilities and improving the divertor configuration. The TCV tokamak is extensively used to investigate the extent that geometric configuration modifications can affect plasma exhaust performance. Recent TCV experiments continue previous detachment studies of Ohmically heated L-mode plasmas in standard single-null configurations, benefitting from a range of improved diagnostic capabilities. Studies were extended to nitrogen seeding and an entire suite of alternative magnetic configurations, including flux flaring towards the target (X divertor), increasing the outer target radius (Super-X) and movement of a secondary x-point inside the vessel (X-point target) as well as the entire range of snowflake configurations. Nitrogen seeding into a snowflake minus configuration demonstrated a regime with strong radiation in the large region between the two x-points, confirming EMC3-Eirene simulations, and opening a promising path towards highly radiating regimes with limited adverse effects on core performance.

  1. Analytic solutions for colloid transport with time- or depth-dependent retention in porous media

    Science.gov (United States)

    Elucidating and quantifying the transport of industrial nanoparticles (e.g. silver, carbon nanotubes, and graphene oxide) and other colloid-size particles such as viruses and bacteria is important to safeguard and manage the quality of the subsurface environment. Analytic solutions were derived for...

  2. Semianalytical Solutions for Transport in Aquifer and Fractured Clay Matrix System

    Science.gov (United States)

    A three-dimensional mathematical model that describes transport of contaminant in a horizontal aquifer with simultaneous diffusion into a fractured clay formation is proposed. A group of analytical solutions is derived based on specific initial and boundary conditions as well as ...

  3. Determination of a closed-form solution for the multidimensional transport equation using a fractional derivative

    International Nuclear Information System (INIS)

    Zabadal, J.; Vilhena, M.T.; Segatto, C.F.; Pazos, R.P.Ruben Panta.

    2002-01-01

    In this work we construct a closed-form solution for the multidimensional transport equation rewritten in integral form which is expressed in terms of a fractional derivative of the angular flux. We determine the unknown order of the fractional derivative comparing the kernel of the integral equation with the one of the Riemann-Liouville definition of fractional derivative. We report numerical simulations

  4. Determination of a closed-form solution for the multidimensional transport equation using a fractional derivative

    Energy Technology Data Exchange (ETDEWEB)

    Zabadal, J. E-mail: jorge.zabadal@ufrgs.br; Vilhena, M.T. E-mail: vilhena@mat.ufrgs.br; Segatto, C.F. E-mail: cynthia@mat.ufrgs.br; Pazos, R.P.Ruben Panta. E-mail: rpp@mat.pucrgs.br

    2002-07-01

    In this work we construct a closed-form solution for the multidimensional transport equation rewritten in integral form which is expressed in terms of a fractional derivative of the angular flux. We determine the unknown order of the fractional derivative comparing the kernel of the integral equation with the one of the Riemann-Liouville definition of fractional derivative. We report numerical simulations.

  5. Positive solution of a time and energy dependent neutron transport problem

    International Nuclear Information System (INIS)

    Pao, C.V.

    1975-01-01

    A constructive method is given for the determination of a solution and an existence--uniqueness theorem for some nonlinear time and energy dependent neutron transport problems, including the linear transport system. The geometry of the medium under consideration is allowed to be either bounded or unbounded which includes the geometry of a finite or infinite cylinder, a half-space and the whole space R/subm/ (m=1,2,center-dotcenter-dotcenter-dot). Our approach to the problem is by successive approximation which leads to various recursion formulas for the approximations in terms of explicit integrations. It is shown under some Lipschitz conditions on the nonlinear functions, which describe the process of neutrons absorption, fission, and scattering, that the sequence of approximations converges to a unique positive solution. Since these conditions are satisfied by the linear transport equation, all the results for the nonlinear system are valid for the linear transport problem. In the general nonlinear problem, the existence of both local and global solutions are discussed, and an iterative process for the construction of the solution is given

  6. Relationship between application scale and maximum time latency in intelligent transport solutions

    NARCIS (Netherlands)

    Knoop, V.; Lint, J. van; Vries, J.; Kester, L.J.H.M.; Passchier, I.

    2013-01-01

    Congestion is a major problem in large, urbanized areas. Intelligent transport solutions aim to reduce this problem. In general, traffic is monitored with the use of sensors, the resulting data are processed, a traffic state is estimated, and a control measure is computed and implemented. The

  7. Direct interaction between linear electron transfer chains and solute transport systems in bacteria

    NARCIS (Netherlands)

    Elferink, Marieke G.L.; Hellingwerf, Klaas J.; Belkum, Marco J. van; Poolman, Bert; Konings, Wil N.

    1984-01-01

    In studies on alanine and lactose transport in Rhodopseudomonas sphaeroides we have demonstrated that the rate of solute uptake in this phototrophic bacterium is regulated by the rate of light-induced cyclic electron transfer. In the present paper the interaction between linear electron transfer

  8. Application of finite element method in the solution of transport equation

    International Nuclear Information System (INIS)

    Maiorino, J.R.; Vieira, W.J.

    1985-01-01

    It is presented the application of finite element method in the solution of second order transport equation (self-adjoint) for the even parity flux. The angular component is treated by expansion in Legendre polinomials uncoupled of the spatial component, which is approached by an expansion in base functions, interpolated in each spatial element. (M.C.K.) [pt

  9. MaSTiS, microorganism and solute transport in streams, model documentation and user manual

    Science.gov (United States)

    In-stream fate and transport of solutes and microorganisms need to be understood to evaluate suitability of waters for agricultural, recreational, and household uses and eventually minimize surface water contamination. Concerns over safety of this water resulted in development of predictive models f...

  10. Field-scale water flow and solute transport : SWAP model concepts, parameter estimation and case studies = [Waterstroming en transport van opgeloste stoffen op veldschaal

    NARCIS (Netherlands)

    Dam, van J.C.

    2000-01-01

    Water flow and solute transport in top soils are important elements in many environmental studies. The agro- and ecohydrological model SWAP (Soil-Water-Plant-Atmosphere) has been developed to simulate simultaneously water flow, solute transport, heat flow and crop growth at field scale

  11. Modeling study of solute transport in the unsaturated zone. Information and data sets. Volume 1

    International Nuclear Information System (INIS)

    Polzer, W.L.; Fuentes, H.R.; Springer, E.P.; Nyhan, J.W.

    1986-05-01

    The Environmental Science Group (HSE-12) is conducting a study to compare various approaches of modeling water and solute transport in porous media. Various groups representing different approaches will model a common set of transport data so that the state of the art in modeling and field experimentation can be discussed in a positive framework with an assessment of current capabilities and future needs in this area of research. This paper provides information and sets of data that will be useful to the modelers in meeting the objectives of the modeling study. The information and data sets include: (1) a description of the experimental design and methods used in obtaining solute transport data, (2) supporting data that may be useful in modeling the data set of interest, and (3) the data set to be modeled

  12. A nonequilibrium model for reactive contaminant transport through fractured porous media: Model development and semianalytical solution

    Science.gov (United States)

    Joshi, Nitin; Ojha, C. S. P.; Sharma, P. K.

    2012-10-01

    In this study a conceptual model that accounts for the effects of nonequilibrium contaminant transport in a fractured porous media is developed. Present model accounts for both physical and sorption nonequilibrium. Analytical solution was developed using the Laplace transform technique, which was then numerically inverted to obtain solute concentration in the fracture matrix system. The semianalytical solution developed here can incorporate both semi-infinite and finite fracture matrix extent. In addition, the model can account for flexible boundary conditions and nonzero initial condition in the fracture matrix system. The present semianalytical solution was validated against the existing analytical solutions for the fracture matrix system. In order to differentiate between various sorption/transport mechanism different cases of sorption and mass transfer were analyzed by comparing the breakthrough curves and temporal moments. It was found that significant differences in the signature of sorption and mass transfer exists. Applicability of the developed model was evaluated by simulating the published experimental data of Calcium and Strontium transport in a single fracture. The present model simulated the experimental data reasonably well in comparison to the model based on equilibrium sorption assumption in fracture matrix system, and multi rate mass transfer model.

  13. Lateral transport of solutes in microfluidic channels using electrochemically generated gradients in redox-active surfactants.

    Science.gov (United States)

    Liu, Xiaoyang; Abbott, Nicholas L

    2011-04-15

    We report principles for a continuous flow process that can separate solutes based on a driving force for selective transport that is generated by a lateral concentration gradient of a redox-active surfactant across a microfluidic channel. Microfluidic channels fabricated with gold electrodes lining each vertical wall were used to electrochemically generate concentration gradients of the redox-active surfactant 11-ferrocenylundecyl-trimethylammonium bromide (FTMA) in a direction perpendicular to the flow. The interactions of three solutes (a hydrophobic dye, 1-phenylazo-2-naphthylamine (yellow AB), an amphiphilic molecule, 2-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-1-hexadecanoyl-sn-glycero-3-phosphocholine (BODIPY C(5)-HPC), and an organic salt, 1-methylpyridinium-3-sulfonate (MPS)) with the lateral gradients in surfactant/micelle concentration were shown to drive the formation of solute-specific concentration gradients. Two distinct physical mechanisms were identified to lead to the solute concentration gradients: solubilization of solutes by micelles and differential adsorption of the solutes onto the walls of the microchannels in the presence of the surfactant concentration gradient. These two mechanisms were used to demonstrate delipidation of a mixture of BODIPY C(5)-HPC (lipid) and MPS and purification of BODIPY C(5)-HPC from a mixture of BODIPY C(5)-HPC and yellow AB. Overall, the results of this study demonstrate that lateral concentration gradients of redox-active surfactants formed within microfluidic channels can be used to transport solutes across the microfluidic channels in a solute-dependent manner. The approach employs electrical potentials (solutions having high ionic strength (>0.1M), and offers the basis of continuous processes for the purification or separation of solutes in microscale systems. © 2011 American Chemical Society

  14. Biogeochemical processes in a clay formation in situ experiment: Part F - Reactive transport modelling

    Energy Technology Data Exchange (ETDEWEB)

    Tournassat, Christophe, E-mail: c.tournassat@brgm.fr [BRGM, French Geological Survey, Orleans (France); Alt-Epping, Peter [Rock-Water Interaction Group, Institute of Geological Sciences, University of Bern (Switzerland); Gaucher, Eric C. [BRGM, French Geological Survey, Orleans (France); Gimmi, Thomas [Rock-Water Interaction Group, Institute of Geological Sciences, University of Bern (Switzerland)] [Laboratory for Waste Management, Paul Scherrer Institut, Villigen (Switzerland); Leupin, Olivier X. [NAGRA, CH-5430 Wettingen (Switzerland); Wersin, Paul [Gruner Ltd., CH-4020 Basel (Switzerland)

    2011-06-15

    Highlights: > Reactive transport modelling was used to simulate simultaneously solute transport, thermodynamic reactions, ion exchange and biodegradation during an in-situ experiment in a clay-rock formation. > Opalinus clay formation has a high buffering capacity in terms of chemical perturbations caused by bacterial activity. > Buffering capacity is mainly attributed to the carbonate system and to the reactivity of clay surfaces (cation exchange, pH buffering). - Abstract: Reactive transport modelling was used to simulate solute transport, thermodynamic reactions, ion exchange and biodegradation in the Porewater Chemistry (PC) experiment at the Mont Terri Rock Laboratory. Simulations show that the most important chemical processes controlling the fluid composition within the borehole and the surrounding formation during the experiment are ion exchange, biodegradation and dissolution/precipitation reactions involving pyrite and carbonate minerals. In contrast, thermodynamic mineral dissolution/precipitation reactions involving alumo-silicate minerals have little impact on the fluid composition on the time-scale of the experiment. With the accurate description of the initial chemical condition in the formation in combination with kinetic formulations describing the different stages of bacterial activities, it has been possible to reproduce the evolution of important system parameters, such as the pH, redox potential, total organic C, dissolved inorganic C and SO{sub 4} concentration. Leaching of glycerol from the pH-electrode may be the primary source of organic material that initiated bacterial growth, which caused the chemical perturbation in the borehole. Results from these simulations are consistent with data from the over-coring and demonstrate that the Opalinus Clay has a high buffering capacity in terms of chemical perturbations caused by bacterial activity. This buffering capacity can be attributed to the carbonate system as well as to the reactivity of

  15. A numerical solution of the coupled proton-H atom transport equations for the proton aurora

    International Nuclear Information System (INIS)

    Basu, B.; Jasperse, J.R.; Grossbard, N.J.

    1990-01-01

    A numerical code has been developed to solve the coupled proton-H atom linear transport equations for the proton aurora. The transport equations have been simplified by using plane-parallel geometry and the forward-scattering approximations only. Otherwise, the equations and their numerical solutions are exact. Results are presented for the particle fluxes and the energy deposition rates, and they are compared with the previous analytical results that were obtained by using additional simplifying approximations. It is found that although the analytical solutions for the particle fluxes differ somewhat from the numerical solutions, the energy deposition rates calculated by the two methods agree to within a few percent. The accurate particle fluxes given by the numerical code are useful for accurate calculation of the characteristic quantities of the proton aurora, such as the ionization rates and the emission rates

  16. Modeling water flow and solute transport in unsaturated zone inside NSRAWD project

    International Nuclear Information System (INIS)

    Constantin, A.; Diaconu, D.; Bucur, C.; Genty, A.

    2015-01-01

    The NSRAWD project (2010-2013) - Numerical Simulations for Radioactive Waste Disposal was initiated under a collaboration agreement between the Institute for Nuclear Research and the French Alternative Energies and Atomic Energy Commission (CEA). The context of the project was favorable to combine the modeling activities with an experimental part in order to improve and validate the numerical models used so far to simulate water flow and solute transport at Saligny site, Romania. The numerical models developed in the project were refined and validated on new hydrological data gathered between 2010-2012 by a monitoring station existent on site which performs automatic determination of soil water content and matrix potential, as well as several climate parameters (wind, temperature and precipitations). Water flow and solute transport was modeled in transient conditions, by taking into consideration, as well as neglecting the evapotranspiration phenomenon, on the basis of a tracer test launched on site. The determination of dispersivities for solute transport was targeted from the solute plume. The paper presents the main results achieved in the NSRAWD project related to water flow and solute transport in the unsaturated area of the Saligny site. The results indicated satisfactory predictions for the simulation of water flow in the unsaturated area, in steady state and transient conditions. In the case of tracer transport modeling, dispersivity coefficients could not be finally well fitted for the data measured on site and in order to obtain a realistic preview over the values of these parameters, further investigations are recommended. The article is followed by the slides of the presentation

  17. A complete NUHOMS {sup registered} solution for storage and transport of high burnup spent fuel

    Energy Technology Data Exchange (ETDEWEB)

    Bondre, J. [Transnuclear, Inc. (AREVA Group), Fremont, CA (United States)

    2004-07-01

    The discharge burnups of spent fuel from nuclear power plants keep increasing with plants discharging or planning to discharge fuel with burnups in excess of 60,000 MWD/MTU. Due to limited capacity of spent fuel pools, transfer of older cooler spent fuel from fuel pool to dry storage, and very limited options for transport of spent fuel, there is a critical need for dry storage of high burnup, higher heat load spent fuel so that plants could maintain their full core offload reserve capability. A typical NUHOMS {sup registered} solution for dry spent fuel storage is shown in the Figure 1. Transnuclear, Inc. offers two advanced NUHOMS {sup registered} solutions for the storage and transportation of high burnup fuel. One includes the NUHOMS {sup registered} 24PTH system for plants with 90.7 Metric Ton (MT) crane capacity; the other offers the higher capacity NUHOMS {sup registered} 32PTH system for higher crane capacity. These systems include NUHOMS {sup registered} - 24PTH and -32PTH Transportable Canisters stored in a concrete storage overpack (HSM-H). These canisters are designed to meet all the requirements of both storage and transport regulations. They are designed to be transported off-site either directly from the spent fuel pool or from the storage overpack in a suitable transport cask.

  18. European experience in transport/storage cask for vitrified residues

    International Nuclear Information System (INIS)

    Otton, Camille; Sicard, Damien

    2007-01-01

    Available in abstract form only. Full text of publication follows: Because of the evolution of burnup of spent fuel to be reprocessed, the high activity vitrified residues would not be transported in the existing cask designs. Therefore, TN International has decided in the late nineties to develop a brand new design of casks with optimized capacity able to store and transport the most active and hottest canisters: the TN TM 81 casks currently in use in Switzerland and the TN TM 85 cask which shall permit in the near future in Germany the storage and the transport of the most active vitrified residues defining a thermal power of 56 kW (kilowatts). The challenges for the TN TM 81 and TN TM 85 cask designs were that the geometry entry data were very restrictive and were combined with a fairly wide range set by the AREVA NC Specification relative to vitrified residue canister. The TN TM 81 and the TN TM 85 casks have been designed to fully anticipate shipment constraints of the present vitrified residue production. It also used the feedback of current shipments and the operational constraints and experience of receiving and shipping facilities. The casks had to fit as much as possible in the existing procedures for the already existing flasks such as the TN TM 28 cask and TS 28 V cask, all along the logistics chain of loading, unloading, transport and maintenance. (authors)

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

    Science.gov (United States)

    R. Haggerty

    2013-01-01

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

  20. Neutron and gamma-ray transport experiments in liquid air

    International Nuclear Information System (INIS)

    Farley, W.E.

    1976-01-01

    Accurate estimates of neutron and gamma radiations from a nuclear explosion and their subsequent transport through the atmosphere are vital to nuclear-weapon employment studies: i.e., for determining safety radii for aircraft crews, casualty and collateral-damage risk radii for tactical weapons, and the kill range from a high-yield defensive burst for a maneuvering reentry vehicle. Radiation transport codes, such as the Laboratory's TARTNP, are used to calculate neutron and gamma fluences. Experiments have been performed to check and update these codes. Recently, a 1.3-m-radius liquid-air (21 percent oxygen) sphere, with a pulsed source of 14-MeV neutrons at its center, was used to measure the fluence and spectra of emerging neutrons and secondary gamma rays. Comparison of measured radiation dose with TARTNP showed agreement within 10 percent

  1. Control and optimization of solute transport in a thin porous tube

    KAUST Repository

    Griffiths, I. M.

    2013-03-01

    Predicting the distribution of solutes or particles in flows within porous-walled tubes is essential to inform the design of devices that rely on cross-flow filtration, such as those used in water purification, irrigation devices, field-flow fractionation, and hollow-fibre bioreactors for tissue-engineering applications. Motivated by these applications, a radially averaged model for fluid and solute transport in a tube with thin porous walls is derived by developing the classical ideas of Taylor dispersion. The model includes solute diffusion and advection via both radial and axial flow components, and the advection, diffusion, and uptake coefficients in the averaged equation are explicitly derived. The effect of wall permeability, slip, and pressure differentials upon the dispersive solute behaviour are investigated. The model is used to explore the control of solute transport across the membrane walls via the membrane permeability, and a parametric expression for the permeability required to generate a given solute distribution is derived. The theory is applied to the specific example of a hollow-fibre membrane bioreactor, where a uniform delivery of nutrient across the membrane walls to the extra-capillary space is required to promote spatially uniform cell growth. © 2013 American Institute of Physics.

  2. Non-cooperative and cooperative solutions of government subsidy on public transportation

    Directory of Open Access Journals (Sweden)

    Husniah Hennie

    2018-01-01

    Full Text Available The paper deals with two models of government subsidy given to a public transport operator: (i the subsidy for buying bus from an appointed public transport manufacturer, and (ii the subsidy for reimbursing reduced ticket price for passengers. The models are developed to determine the maximum profit for both the public transport operator and the manufacturer. Since we consider two parties – the public transport operator and the manufacturer of the bus, then we use game theoretical approach by considering non-cooperative and cooperative solutions. Furthermore, since the bus is repairable we consider virtual age to model the preventive maintenance and we consider minimal repair to model the corrective maintenance. We analyse both type of subsidy models and give some numerical examples which show the effects of different subsidies to the profit of operator and manufacturer. The result of the numerical examples indicates that reducing ticket price would give a higher profit both to the operator and the manufacturer.

  3. Modeling of water flow and solute transport in unsaturated heterogeneous fields

    International Nuclear Information System (INIS)

    Bresler, E.; Dagan, G.

    1982-01-01

    A comprehensive model which considers dispersive solute transport, nonsteady moisture flow regimes and complex boundary conditions is described. The main assumptions are: vertical flow; spatial variability which is associated with the saturated hydraulic conductivity K/sub s/ occurs in the horizontal plane, but is constant in the profile, and has a lognormal probability distribution function (PDF); deterministic recharge and solute concentration are applied during infiltration; the soil is at uniform water content and salt concentration prior to infiltration. The problem is to solve, for arbitrary K/sub s/, the Richards' equation of flow simultaneously with the diffusion-convection equation for salt transport, with the boundary and initial conditions appropriate to infiltration-redistribution. Once this is achieved, the expectation and variance of various quantities of interest (solute concentration, moisture content) are obtained by using the statistical averaging procedure and the given PDF of K/sub s/. Since the solution of Richards' equation for the infiltration-redistribution cycle is extremely difficult (for a given K/sub s/), an approxiate solution is derived by using the concept of piston flow type wetting fronts. Similarly, accurate numerical solutions are used as input for the same statistical averaging procedure. The stochastic model is applied to two spatially variable soils by using both accurate numerical solutions and the simplified water and salt transport models. A comparison between the results shows that the approximate simplified models lead to quite accurate values of the expectations and variances of the flow variables for the entire field. It is suggested that in spatially variable fields, stochastic modeling represents the actual flow phenomena realistically, and provides the main statistical moments by using simplified flow models which can be used with confidence in applications

  4. Lived experience of involuntary transport under mental health legislation.

    Science.gov (United States)

    Bradbury, Joanne; Hutchinson, Marie; Hurley, John; Stasa, Helen

    2017-12-01

    Police have historically been responsible for transporting people during a mental health crisis in Australia. A major change to the New South Wales (NSW) Mental Health Act (MHA) in 2007 expanded the range of coercive transportation agencies to include NSW Ambulance (paramedics) and NSW Health (mental health nurses). Anecdotal reports, however, describe a lack of clarity around how these changes should be implemented in practice. This research aims to explore this lack of clarity through qualitative analysis of interviews with people with the lived experience of involuntary transport under the MHA. Sixteen interviews were conducted; most (n = 14) interviews in northern NSW regions: six with people who had been transported (consumers), four with carers, and six with service providers (two police, one paramedic, and three mental health nurses). For consumers and carers, the police response was often perceived as too intense, particularly if the person was not violent. Carers were often conflicted by having to call for emergency intervention. Service providers were frustrated by a lack of a coordinated interagency response, resourcing issues, delays at emergency departments, and lack of adequate training. A central theme across all groups was the importance of communication styles. As one participant (consumer) said: 'Everybody needs a lesson in kindness'. All groups agreed that high-risk situations necessitate police involvement. However, invocation of the MHA during a high-risk situation is fraught with stress and difficulties, leaving little room for empathetic communications. Effective and diverse, evidence-based, early intervention strategies - both consensual and non-consensual - are necessary to reduce the requirement for police involvement in mental health transports. © 2016 Australian College of Mental Health Nurses Inc.

  5. IPROP simulations of the GAMBLE II proton transport experiment

    International Nuclear Information System (INIS)

    Welch, D.R.

    1993-01-01

    The author has simulated the proton transport of the 6-kA, 1-MV GAMBLE II experiment using a modified version of the IPROP particle-in-cell code. IPROP now uses a hybrid model in which plasma electrons are divided into high-energy macro particle and thermal-fluid components. This model includes open-quotes knock-onclose quotes bound-electron collision and runaway sources for high-energy electrons. Using IPROP, the authors has calculated net currents in reasonable agreement with the experiment ranging from 5-11% of the total current in pressures from 0.25-4 torr helium. In the simulations, the pinch current sample by the 1.5-cm beam was 2-3 times larger than the net current at 4 cm radius. The attenuation of net current at larger radii was the result of a highly-conductive energetic component of plasma electrons surrounding the beam. Having benchmarked IPROP against experiment, the author has examined higher-current ion beams with respect to possible transport for inertial confinement fusion

  6. Combining metadynamics simulation and experiments to characterize dendrimers in solution

    NARCIS (Netherlands)

    Pavan, G.M.; Barducci, A.; Albertazzi, L.; Parrinello, M.

    2013-01-01

    We report a combined theoretical-experimental approach to characterize dendrimers and Polyethylene Glycol (PEG)-dendrimer hybrids in solution. Well-tempered metadynamics simulation allows for an exhaustive sampling of the conformational fluctuations in solution. In contrast to classical molecular

  7. Solute transport on the sub 100 ms scale across the lipid bilayer membrane of individual proteoliposomes.

    Science.gov (United States)

    Ohlsson, Gabriel; Tabaei, Seyed R; Beech, Jason; Kvassman, Jan; Johanson, Urban; Kjellbom, Per; Tegenfeldt, Jonas O; Höök, Fredrik

    2012-11-21

    Screening assays designed to probe ligand and drug-candidate regulation of membrane proteins responsible for ion-translocation across the cell membrane are wide spread, while efficient means to screen membrane-protein facilitated transport of uncharged solutes are sparse. We report on a microfluidic-based system to monitor transport of uncharged solutes across the membrane of multiple (>100) individually resolved surface-immobilized liposomes. This was accomplished by rapidly switching (solution above dye-containing liposomes immobilized on the floor of a microfluidic channel. With liposomes encapsulating the pH-sensitive dye carboxyfluorescein (CF), internal changes in pH induced by transport of a weak acid (acetic acid) could be measured at time scales down to 25 ms. The applicability of the set up to study biological transport reactions was demonstrated by examining the osmotic water permeability of human aquaporin (AQP5) reconstituted in proteoliposomes. In this case, the rate of osmotic-induced volume changes of individual proteoliposomes was time resolved by imaging the self quenching of encapsulated calcein in response to an osmotic gradient. Single-liposome analysis of both pure and AQP5-containing liposomes revealed a relatively large heterogeneity in osmotic permeability. Still, in the case of AQP5-containing liposomes, the single liposome data suggest that the membrane-protein incorporation efficiency depends on liposome size, with higher incorporation efficiency for larger liposomes. The benefit of low sample consumption and automated liquid handling is discussed in terms of pharmaceutical screening applications.

  8. Analytical solution for the transport equation for neutral particles in cylindrical and Cartesian geometry

    International Nuclear Information System (INIS)

    Goncalves, Glenio Aguiar

    2003-01-01

    In this work, we are reported analytical solutions for the transport equation for neutral particles in cylindrical and cartesian geometry. For the cylindrical geometry, it is applied the Hankel transform of order zero in the S N approximation of the one-dimensional cylindrical transport equation, assuming azimuthal symmetry and isotropic scattering. This procedure is coined HTSN method. The anisotropic problem is handled using the decomposition method, generating a recursive approach, which the HTSN solution is used as initial condition. For cartesian geometry, the one and two dimensional transport equation is derived in the angular variable as many time as the degree of the anisotropic scattering. This procedure leads to set of integro-differential plus one differential equation that can be really solved by the variable separation method. Following this procedure, it was possible to come out with the Case solution for the one-dimensional problem. Numerical simulations are reported for the cylindrical transport problem both isotropic and anisotropic case of quadratic degree. (author)

  9. Plans for longitudinal and transverse neutralized beam compression experiments, and initial results from solenoid transport experiments

    International Nuclear Information System (INIS)

    Seidl, P.A.; Armijo, J.; Baca, D.; Bieniosek, F.M.; Coleman, J.; Davidson, R.C.; Efthimion, P.C.; Friedman, A.; Gilson, E.P.; Grote, D.; Haber, I.; Henestroza, E.; Kaganovich, I.; Leitner, M.; Logan, B.G.; Molvik, A.W.; Rose, D.V.; Roy, P.K.; Sefkow, A.B.; Sharp, W.M.; Vay, J.L.; Waldron, W.L.; Welch, D.R.; Yu, S.S.

    2007-01-01

    This paper presents plans for neutralized drift compression experiments, precursors to future target heating experiments. The target-physics objective is to study warm dense matter (WDM) using short-duration (∼1 ns) ion beams that enter the targets at energies just above that at which dE/dx is maximal. High intensity on target is to be achieved by a combination of longitudinal compression and transverse focusing. This work will build upon recent success in longitudinal compression, where the ion beam was compressed lengthwise by a factor of more than 50 by first applying a linear head-to-tail velocity tilt to the beam, and then allowing the beam to drift through a dense, neutralizing background plasma. Studies on a novel pulse line ion accelerator were also carried out. It is planned to demonstrate simultaneous transverse focusing and longitudinal compression in a series of future experiments, thereby achieving conditions suitable for future WDM target experiments. Future experiments may use solenoids for transverse focusing of un-neutralized ion beams during acceleration. Recent results are reported in the transport of a high-perveance heavy ion beam in a solenoid transport channel. The principal objectives of this solenoid transport experiment are to match and transport a space-charge-dominated ion beam, and to study associated electron-cloud and gas effects that may limit the beam quality in a solenoid transport system. Ideally, the beam will establish a Brillouin-flow condition (rotation at one-half the cyclotron frequency). Other mechanisms that potentially degrade beam quality are being studied, such as focusing-field aberrations, beam halo, and separation of lattice focusing elements

  10. Dynamics of T-Junction Solution Switching Aimed at Patch Clamp Experiments.

    Science.gov (United States)

    Auzmendi, Jerónimo A; Smoler, Mariano; Moffatt, Luciano

    2015-01-01

    Solutions exchange systems are responsible for the timing of drug application on patch clamp experiments. There are two basic strategies for generating a solution exchange. When slow exchanges are bearable, it is easier to perform the exchange inside the tubing system upstream of the exit port. On the other hand, fast, reproducible, exchanges are usually performed downstream of the exit port. As both strategies are combinable, increasing the performance of upstream exchanges is desirable. We designed a simple method for manufacturing T-junctions (300 μm I.D.) and we measured the time profile of exchange of two saline solutions using a patch pipette with an open tip. Three factors were found to determine the timing of the solution switching: pressure, travelled distance and off-center distance. A linear relationship between the time delay and the travelled distance was found for each tested pressure, showing its dependence to the fluid velocity, which increased with pressure. The exchange time was found to increase quadratically with the delay, although a sizeable variability remains unexplained by this relationship. The delay and exchange times increased as the recording pipette moved away from the center of the stream. Those increases became dramatic as the pipette was moved close to the stream borders. Mass transport along the travelled distance between the slow fluid at the border and the fast fluid at the center seems to contribute to the time course of the solution exchange. This effect would be present in all tubing based devices. Present results might be of fundamental importance for the adequate design of serial compound exchangers which would be instrumental in the discovery of drugs that modulate the action of the physiological agonists of ion channels with the purpose of fine tuning their physiology.

  11. United States experience in the transportation of radioactive materials

    International Nuclear Information System (INIS)

    Platt, A.M.; Rhoads, R.E.; Hall, R.J.; Williams, L.D.; Brobst, W.A.; Shappert, L.B.; Jefferson, R.M.

    1977-01-01

    The transport of radioactive material forms a vital link in the nuclear fuel cycle in the United States. Actual U.S. experience and practice with such systems for the packaging and transport of uranium ore concentrates, uranium hexafluoride, fresh fuel, irradiated fuel, non-high-level waste, and plutonium with low heat generation rates are described. Specific shipping systems in current use for these services are illustrated. A comparison will be made of shipping requirements for nuclear parks versus dispersed facilities. Shipping systems for other fuel cycle materials (e.g., high-level waste and cladding hulls) have not been developed because there has been no need to transport these materials commercially. However, conceptual designs for packaging and transport of such materials have been developed. Selected systems are reviewed and summarized. Transport safety in the U.S. is regulated by the U.S. Department of Transportation and the Nuclear Regulatory Commission. Key regulations defining packaging requirements, allowable radiation dose rates, and handling procedures are reviewed. Although the radioactive material shipping industry has an outstanding safety record, opposition to nuclear fuel cycle shipments has surfaced in several areas. The U.S. congressional ban on the shipment of plutonium by air, the actions of New York City to prohibit certain shipments within the city limits, and the requirement of U.S. railroads to ship spent fuel casks only in dedicated trains are reviewed. In an attempt to provide information on the safety margins inherent in the design of radioactive materials packages, ERDA has undertaken a series of accident studies and full scale crash tests that stress the packages beyond the levels expected in severe accidents. In addition, the level of total risk associated with radioactive materials shipments is being evaluated. Current ERDA crash test and transportation risk assessment studies are reviewed. Concern about the possibility of

  12. Numerical modeling of solute transport in a sand tank physical model under varying hydraulic gradient and hydrological stresses

    Science.gov (United States)

    Atlabachew, Abunu; Shu, Longcang; Wu, Peipeng; Zhang, Yongjie; Xu, Yang

    2018-03-01

    This laboratory study improves the understanding of the impacts of horizontal hydraulic gradient, artificial recharge, and groundwater pumping on solute transport through aquifers. Nine experiments and numerical simulations were carried out using a sand tank. The variable-density groundwater flow and sodium chloride transport were simulated using the three-dimensional numerical model SEAWAT. Numerical modelling results successfully reproduced heads and concentrations observed in the sand tank. A higher horizontal hydraulic gradient enhanced the migration of sodium chloride, particularly in the groundwater flow direction. The application of constant artificial recharge increased the spread of the sodium chloride plume in both the longitudinal and lateral directions. In addition, groundwater pumping accelerated spreading of the sodium chloride plume towards the pumping well. Both higher hydraulic gradient and pumping rate generated oval-shaped plumes in the horizontal plane. However, the artificial recharge process produced stretched plumes. These effects of artificial recharge and groundwater pumping were greater under higher hydraulic gradient. The concentration breakthrough curves indicated that emerging solutions never attained the concentration of the originally injected solution. This is probably because of sorption of sodium chloride onto the silica sand and/or the exchange of sodium chloride between the mobile and immobile liquid domains. The fingering and protruding plume shapes in the numerical models constitute instability zones produced by buoyancy-driven flow. Overall, the results have substantiated the influences of hydraulic gradient, boundary condition, artificial recharge, pumping rate and density differences on solute transport through a homogeneous unconfined aquifer. The implications of these findings are important for managing liquid wastes.

  13. THE IMPORTANCE OF LIMIT SOLUTIONS & TEMPORAL AND SPATIAL SCALES IN THE TEACHING OF TRANSPORT PHENOMENA

    Directory of Open Access Journals (Sweden)

    SÁVIO LEANDRO BERTOLI

    2016-07-01

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

  14. Exact solutions of Fisher and Burgers equations with finite transport memory

    International Nuclear Information System (INIS)

    Kar, Sandip; Banik, Suman Kumar; Ray, Deb Shankar

    2003-01-01

    The Fisher and Burgers equations with finite memory transport, describing reaction-diffusion and convection-diffusion processes, respectively have recently attracted a lot of attention in the context of chemical kinetics, mathematical biology and turbulence. We show here that they admit exact solutions. While the speed of the travelling wavefront is dependent on the relaxation time in the Fisher equation, memory effects significantly smoothen out the shock wave nature of the Burgers solution, without any influence on the corresponding wave speed. We numerically analyse the ansatz for the exact solution and show that for the reaction-diffusion system the strength of the reaction term must be moderate enough not to exceed a critical limit to allow a travelling wave solution to exist for appreciable finite memory effect

  15. Exact solutions of Fisher and Burgers equations with finite transport memory

    CERN Document Server

    Kar, S; Ray, D S

    2003-01-01

    The Fisher and Burgers equations with finite memory transport, describing reaction-diffusion and convection-diffusion processes, respectively have recently attracted a lot of attention in the context of chemical kinetics, mathematical biology and turbulence. We show here that they admit exact solutions. While the speed of the travelling wavefront is dependent on the relaxation time in the Fisher equation, memory effects significantly smoothen out the shock wave nature of the Burgers solution, without any influence on the corresponding wave speed. We numerically analyse the ansatz for the exact solution and show that for the reaction-diffusion system the strength of the reaction term must be moderate enough not to exceed a critical limit to allow a travelling wave solution to exist for appreciable finite memory effect.

  16. Exact solutions of the population balance equation including particle transport, using group analysis

    Science.gov (United States)

    Lin, Fubiao; Meleshko, Sergey V.; Flood, Adrian E.

    2018-06-01

    The population balance equation (PBE) has received an unprecedented amount of attention in recent years from both academics and industrial practitioners because of its long history, widespread use in engineering, and applicability to a wide variety of particulate and discrete-phase processes. However it is typically impossible to obtain analytical solutions, although in almost every case a numerical solution of the PBEs can be obtained. In this article, the symmetries of PBEs with homogeneous coagulation kernels involving aggregation, breakage and growth processes and particle transport in one dimension are found by direct solving the determining equations. Using the optimal system of one and two-dimensional subalgebras, all invariant solutions and reduced equations are obtained. In particular, an explicit analytical physical solution is also presented.

  17. X-ray CT-Derived Soil Characteristics Explain Varying Air, Water, and Solute Transport Properties across a Loamy Field

    DEFF Research Database (Denmark)

    Paradelo Pérez, Marcos; Katuwal, Sheela; Møldrup, Per

    2016-01-01

    -derived parameters by using a best subsets regression analysis. The regression coefficients improved using CTmatrix, limiting macroporosity, and genus density, while the best model for t0.05 used CTmatrix only. The scanning resolution and the time for soil structure development after mechanical activities could......The characterization of soil pore space geometry is important for explaining fluxes of air, water, and solutes through soil and understanding soil hydrogeochemical functions. X-ray computed tomography (CT) can be applied for this characterization, and in this study CT-derived parameters were used...... to explain water, air, and solute transport through soil. Forty-five soil columns (20 by 20 cm) were collected from an agricultural field in Estrup, Denmark, and subsequently scanned using a medical CT scanner. Nonreactive tracer leaching experiments were performed in the laboratory along with measurements...

  18. Water and Solute Transport in Arid Vadose Zones: Innovations in Measurement and Analysis

    International Nuclear Information System (INIS)

    Tyler, S W.; Scanlon, Bridget R.; Gee, Glendon W.; Allison, G B.; Parlange, M. B.; Hopmans, J. W.

    1999-01-01

    Understanding the physics of flow and transport through the vadose zone has advanced significantly in the last three decades. These advances have been made primarily in humid regions or in irrigated agricultural settings. While some of the techniques are useful, many are not suited to arid regions. The fluxes of water and solutes typically found in arid regions are often orders of magnitude smaller than those found in agricultural settings, while the time scales for transport can be orders of magnitude larger. The depth over which transport must be characterized is also often much greater than in humid regions. Rather than relying on advances in applied tracers, arid-zone researchers have developed natural tracer techniques that are capable of quantifying transport over tens to thousands of years. Techniques have been developed to measure the hydraulic properties of sediments at all water contents, including the very dry range and at far greater depths. As arid and semiarid regions come under increased development pressures for such activities as hazardous- and radioactive-waste disposal, the development of techniques and the understanding of water and solute transport have become crucial components in defining the environmental impacts of activities at the landsurface

  19. CFEST Coupled Flow, Energy & Solute Transport Version CFEST005 User’s Guide

    Energy Technology Data Exchange (ETDEWEB)

    Freedman, Vicky L.; Chen, Yousu; Gilca, Alex; Cole, Charles R.; Gupta, Sumant K.

    2006-07-20

    The CFEST (Coupled Flow, Energy, and Solute Transport) simulator described in this User’s Guide is a three-dimensional finite-element model used to evaluate groundwater flow and solute mass transport. Confined and unconfined aquifer systems, as well as constant and variable density fluid flows can be represented with CFEST. For unconfined aquifers, the model uses a moving boundary for the water table, deforming the numerical mesh so that the uppermost nodes are always at the water table. For solute transport, changes in concentra¬tion of a single dissolved chemical constituent are computed for advective and hydrodynamic transport, linear sorption represented by a retardation factor, and radioactive decay. Although several thermal parameters described in this User’s Guide are required inputs, thermal transport has not yet been fully implemented in the simulator. Once fully implemented, transport of thermal energy in the groundwater and solid matrix of the aquifer can also be used to model aquifer thermal regimes. The CFEST simulator is written in the FORTRAN 77 language, following American National Standards Institute (ANSI) standards. Execution of the CFEST simulator is controlled through three required text input files. These input file use a structured format of associated groups of input data. Example input data lines are presented for each file type, as well as a description of the structured FORTRAN data format. Detailed descriptions of all input requirements, output options, and program structure and execution are provided in this User’s Guide. Required inputs for auxillary CFEST utilities that aide in post-processing data are also described. Global variables are defined for those with access to the source code. Although CFEST is a proprietary code (CFEST, Inc., Irvine, CA), the Pacific Northwest National Laboratory retains permission to maintain its own source, and to distribute executables to Hanford subcontractors.

  20. Multiscale Roughness Influencing on Transport Behavior of Passive Solute through a Single Self-affine Fracture

    Science.gov (United States)

    Dou, Z.

    2017-12-01

    In this study, the influence of multi-scale roughness on transport behavior of the passive solute through the self-affine fracture was investigated. The single self-affine fracture was constructed by the successive random additions (SRA) and the fracture roughness was decomposed into two different scales (i.e. large-scale primary roughness and small-scale secondary roughness) by the Wavelet analysis technique. The fluid flow in fractures, which was characterized by the Forchheimer's law, showed the non-linear flow behaviors such as eddies and tortuous streamlines. The results indicated that the small-scale secondary roughness was primarily responsible for the non-linear flow behaviors. The direct simulations of asymptotic passive solute transport represented the Non-Fickian transport characteristics (i.e. early arrivals and long tails) in breakthrough curves (BTCs) and residence time distributions (RTDs) with and without consideration of the secondary roughness. Analysis of multiscale BTCs and RTDs showed that the small-scale secondary roughness played a significant role in enhancing the Non-Fickian transport characteristics. We found that removing small-scale secondary roughness led to the lengthening arrival and shortening tail. The peak concentration in BTCs decreased as the secondary roughness was removed, implying that the secondary could also enhance the solute dilution. The estimated BTCs by the Fickian advection-dispersion equation (ADE) yielded errors which decreased with the small-scale secondary roughness being removed. The mobile-immobile model (MIM) was alternatively implemented to characterize the Non-Fickian transport. We found that the MIM was more capable of estimating Non-Fickian BTCs. The small-scale secondary roughness resulted in the decreasing mobile domain fraction and the increasing mass exchange rate between immobile and mobile domains. The estimated parameters from the MIM could provide insight into the inherent mechanism of roughness

  1. Modeling of Flow, Transport and Controlled Sedimentation Phenomena during Mixing of Salt Solutions in Complex Porous Formations

    Science.gov (United States)

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

    2015-04-01

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

  2. Implementation of Solute Transport in the Vadose Zone into the `HYDRUS Package for MODFLOW'

    Science.gov (United States)

    Simunek, J.; Beegum, S.; Szymkiewicz, A.; Sudheer, K. P.

    2017-12-01

    The 'HYDRUS package for MODFLOW' was developed by Seo et al. (2007) and Twarakavi et al. (2008) to simultaneously evaluate transient water flow in both unsaturated and saturated zones. The package, which is based on the HYDRUS-1D model (Šimůnek et al., 2016) simulating unsaturated water flow in the vadose zone, was incorporated into MODFLOW (Harbaugh et al., 2000) simulating saturated groundwater flow. The HYDRUS package in the coupled model can be used to represent the effects of various unsaturated zone processes, including infiltration, evaporation, root water uptake, capillary rise, and recharge in homogeneous or layered soil profiles. The coupled model is effective in addressing spatially-variable saturated-unsaturated hydrological processes at the regional scale, allowing for complex layering in the unsaturated zone, spatially and temporarily variable water fluxes at the soil surface and in the root zone, and with alternating recharge and discharge fluxes (Twarakavi et al., 2008). One of the major limitations of the coupled model was that it could not be used to simulate at the same time solute transport. However, solute transport is highly dependent on water table fluctuations due to temporal and spatial variations in groundwater recharge. This is an important concern when the coupled model is used for analyzing groundwater contamination due to transport through the unsaturated zone. The objective of this study is to integrate the solute transport model (the solute transport part of HYDRUS-1D for the unsaturated zone and MT3DMS (Zheng and Wang, 1999; Zheng, 2009) for the saturated zone) into an existing coupled water flow model. The unsaturated zone component of the coupled model can consider solute transport involving many biogeochemical processes and reactions, including first-order degradation, volatilization, linear or nonlinear sorption, one-site kinetic sorption, two-site sorption, and two-kinetic sites sorption (Šimůnek and van Genuchten, 2008

  3. Air medical transport personnel experiences with and opinions about research.

    Science.gov (United States)

    Fox, Jolene; Thomas, Frank; Carpenter, Judi; Handrahan, Diana

    2010-01-01

    This study examined air medical transport (AMT) personnel's experiences with and opinions about prehospital and AMT research. A Web-based questionnaire was sent to eight randomly selected AMT programs from each of six Association of Air Medical Services (AAMS) regions. Responders were defined by university association (UA) and AMT professional role. Forty-eight of 54 (89%) contacted programs and 536 of 1,282 (42%) individuals responded. Non-UA responders (74%) had significantly more work experience in emergency medical services (EMS) (13.5 +/- 8.5 vs. 10.8 +/- 8.3 years, P = .002) and AMT (8.3 +/- 6.3 vs. 6.8 +/- 5.7 years, P = .008), whereas UA responders (26%) had more research training (51% vs. 37%, P = .006), experience (79% vs. 59%, P < .001), and grants (7% vs. 2%, P = .006). By AMT role, administrators had the most work experience, and physicians had the most research experience. Research productivity of responders was low, with only 9% having presented and 10% having published research; and UA made no difference in productivity. A majority of responders advocated research: EMS (66%) and AMT (68%), program (53%). Willingness to participate in research was high for both EMS research (87%) and AMT research (92%). Although AMT personnel were strong advocates of and willing to participate in research, few had research knowledge. For AMT personnel, disparity exists between advocating for and producing research. Copyright 2010 Air Medical Journal Associates. Published by Elsevier Inc. All rights reserved.

  4. The use of non-dimensional representation of the solute transport equations

    International Nuclear Information System (INIS)

    Laurens, J.-M.

    1988-07-01

    This report presents the results obtained in a pilot investigation into the use of non-dimensional representations of the solute transport equations, so as to improve the efficiency of the PRA codes used by the DoE and its contractors. A reduced set of parameters was obtained for a single layer transport model. As expected, the response was shown to be highly sensitive on the new parameters. A faster convergence of the system was observed when the sampling technique used was changed to take into account the properties of the new parameters, such that uniform coverage of the reduced parameter hyperspace was achieved. (author)

  5. Approximate solutions for the two-dimensional integral transport equation. The critically mixed methods of resolution

    International Nuclear Information System (INIS)

    Sanchez, Richard.

    1980-11-01

    This work is divided into two part the first part (note CEA-N-2165) deals with the solution of complex two-dimensional transport problems, the second one treats the critically mixed methods of resolution. These methods are applied for one-dimensional geometries with highly anisotropic scattering. In order to simplify the set of integral equation provided by the integral transport equation, the integro-differential equation is used to obtain relations that allow to lower the number of integral equation to solve; a general mathematical and numerical study is presented [fr

  6. Modeling particle-facilitated solute transport using the C-Ride module of HYDRUS

    Science.gov (United States)

    Simunek, Jiri; Bradford, Scott A.

    2017-04-01

    Strongly sorbing chemicals (e.g., heavy metals, radionuclides, pharmaceuticals, and/or explosives) in soils are associated predominantly with the solid phase, which is commonly assumed to be stationary. However, recent field- and laboratory-scale observations have shown that, in the presence of mobile colloidal particles (e.g., microbes, humic substances, clays and metal oxides), the colloids could act as pollutant carriers and thus provide a rapid transport pathway for strongly sorbing contaminants. Such transport can be further accelerated since these colloidal particles may travel through interconnected larger pores where the water velocity is relatively high. Additionally, colloidal particles have a considerable adsorption capacity for other species present in water because of their large specific surface areas and their high concentrations in soil-water and groundwater. As a result, the transport of contaminants can be significantly, sometimes dramatically, enhanced when they are adsorbed to mobile colloids. To address this problem, we have developed the C-Ride module for HYDRUS-1D. This one-dimensional numerical module is based on the HYDRUS-1D software package and incorporates mechanisms associated with colloid and colloid-facilitated solute transport in variably saturated porous media. This numerical model accounts for both colloid and solute movement due to convection, diffusion, and dispersion in variably-saturated soils, as well as for solute movement facilitated by colloid transport. The colloids transport module additionally considers processes of attachment/detachment to/from the solid phase, straining, and/or size exclusion. Various blocking and depth dependent functions can be used to modify the attachment and straining coefficients. The module additionally considers the effects of changes in the water content on colloid/bacteria transport and attachment/detachment to/from solid-water and air-water interfaces. For example, when the air

  7. Spatially distributed characterization of hyporheic solute transport during baseflow recession in a headwater mountain stream using electrical geophysical imaging

    Science.gov (United States)

    Adam S. Ward; Michael N. Gooseff; Michael Fitzgerald; Thomas J. Voltz; Kamini Singha

    2014-01-01

    The transport of solutes along hyporheic flowpaths is recognized as central to numerous biogeochemical cycles, yet our understanding of how this transport changes with baseflow recession, particularly in a spatially distributed manner, is limited. We conducted four steady-state solute tracer injections and collected electrical resistivity data to characterize hyporheic...

  8. Multiphasic modeling of charged solute transport across articular cartilage: Application of multi-zone finite-bath model.

    Science.gov (United States)

    Arbabi, Vahid; Pouran, Behdad; Weinans, Harrie; Zadpoor, Amir A

    2016-06-14

    Charged and uncharged solutes penetrate through cartilage to maintain the metabolic function of chondrocytes and to possibly restore or further breakdown the cartilage tissue in different stages of osteoarthritis. In this study the transport of charged solutes across the various zones of cartilage was quantified, taken into account the physicochemical interactions between the solute and the cartilage constituents. A multiphasic finite-bath finite element (FE) model was developed to simulate equine cartilage diffusion experiments that used a negatively charged contrast agent (ioxaglate) in combination with serial micro-computed tomography (micro-CT) to measure the diffusion. By comparing the FE model with the experimental data both the diffusion coefficient of ioxaglate and the fixed charge density (FCD) were obtained. In the multiphasic model, cartilage was divided into multiple (three) zones to help understand how diffusion coefficient and FCD vary across cartilage thickness. The direct effects of charged solute-FCD interaction on diffusion were investigated by comparing the diffusion coefficients derived from the multiphasic and biphasic-solute models. We found a relationship between the FCD obtained by the multiphasic model and ioxaglate partitioning obtained from micro-CT experiments. Using our multi-zone multiphasic model, diffusion coefficient of the superficial zone was up to ten-fold higher than that of the middle zone, while the FCD of the middle zone was up to almost two-fold higher than that of the superficial zone. In conclusion, the developed finite-bath multiphasic model provides us with a non-destructive method by which we could obtain both diffusion coefficient and FCD of different cartilage zones. The outcomes of the current work will also help understand how charge of the bath affects the diffusion of a charged molecule and also predict the diffusion behavior of a charged solute across articular cartilage. Copyright © 2016 Elsevier Ltd. All

  9. A multi scale approximation solution for the time dependent Boltzmann-transport equation

    International Nuclear Information System (INIS)

    Merk, B.

    2004-03-01

    The basis of all transient simulations for nuclear reactor cores is the reliable calculation of the power production. The local power distribution is generally calculated by solving the space, time, energy and angle dependent neutron transport equation known as Boltzmann equation. The computation of exact solutions of the Boltzmann equation is very time consuming. For practical numerical simulations approximated solutions are usually unavoidable. The objective of this work is development of an effective multi scale approximation solution for the Boltzmann equation. Most of the existing methods are based on separation of space and time. The new suggested method is performed without space-time separation. This effective approximation solution is developed on the basis of an expansion for the time derivative of different approximations to the Boltzmann equation. The method of multiple scale expansion is used for the expansion of the time derivative, because the problem of the stiff time behaviour can't be expressed by standard expansion methods. This multiple scale expansion is used in this work to develop approximation solutions for different approximations of the Boltzmann equation, starting from the expansion of the point kinetics equations. The resulting analytic functions are used for testing the applicability and accuracy of the multiple scale expansion method for an approximation solution with 2 delayed neutron groups. The results are tested versus the exact analytical results for the point kinetics equations. Very good agreement between both solutions is obtained. The validity of the solution with 2 delayed neutron groups to approximate the behaviour of the system with 6 delayed neutron groups is demonstrated in an additional analysis. A strategy for a solution with 4 delayed neutron groups is described. A multiple scale expansion is performed for the space-time dependent diffusion equation for one homogenized cell with 2 delayed neutron groups. The result is

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

    International Nuclear Information System (INIS)

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

    1997-09-01

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

  11. Solution of stochastic media transport problems using a numerical quadrature-based method

    International Nuclear Information System (INIS)

    Pautz, S. D.; Franke, B. C.; Prinja, A. K.; Olson, A. J.

    2013-01-01

    We present a new conceptual framework for analyzing transport problems in random media. We decompose such problems into stratified subproblems according to the number of material pseudo-interfaces within realizations. For a given subproblem we assign pseudo-interface locations in each realization according to product quadrature rules, which allows us to deterministically generate a fixed number of realizations. Quadrature integration of the solutions of these realizations thus approximately solves each subproblem; the weighted superposition of solutions of the subproblems approximately solves the general stochastic media transport problem. We revisit some benchmark problems to determine the accuracy and efficiency of this approach in comparison to randomly generated realizations. We find that this method is very accurate and fast when the number of pseudo-interfaces in a problem is generally low, but that these advantages quickly degrade as the number of pseudo-interfaces increases. (authors)

  12. Chain segmentation for the Monte Carlo solution of particle transport problems

    International Nuclear Information System (INIS)

    Ragheb, M.M.H.

    1984-01-01

    A Monte Carlo approach is proposed where the random walk chains generated in particle transport simulations are segmented. Forward and adjoint-mode estimators are then used in conjunction with the firstevent source density on the segmented chains to obtain multiple estimates of the individual terms of the Neumann series solution at each collision point. The solution is then constructed by summation of the series. The approach is compared to the exact analytical and to the Monte Carlo nonabsorption weighting method results for two representative slowing down and deep penetration problems. Application of the proposed approach leads to unbiased estimates for limited numbers of particle simulations and is useful in suppressing an effective bias problem observed in some cases of deep penetration particle transport problems

  13. Three-dimensional transport theory: An analytical solution of an internal beam searchlight problem-I

    International Nuclear Information System (INIS)

    Williams, M.M.R.

    2009-01-01

    We describe a number of methods for obtaining analytical solutions and numerical results for three-dimensional one-speed neutron transport problems in a half-space containing a variety of source shapes which emit neutrons mono-directionally. For example, we consider an off-centre point source, a ring source and a disk source, or any combination of these, and calculate the surface scalar flux as a function of the radial and angular co-ordinates. Fourier transforms in the transverse directions are used and a Laplace transform in the axial direction. This enables the Wiener-Hopf method to be employed, followed by an inverse Fourier-Hankel transform. Some additional transformations are introduced which enable the inverse Hankel transforms involving Bessel functions to be evaluated numerically more efficiently. A hybrid diffusion theory method is also described which is shown to be a useful guide to the general behaviour of the solutions of the transport equation.

  14. DRAGON solutions to the 3D transport benchmark over a range in parameter space

    International Nuclear Information System (INIS)

    Martin, Nicolas; Hebert, Alain; Marleau, Guy

    2010-01-01

    DRAGON solutions to the 'NEA suite of benchmarks for 3D transport methods and codes over a range in parameter space' are discussed in this paper. A description of the benchmark is first provided, followed by a detailed review of the different computational models used in the lattice code DRAGON. Two numerical methods were selected for generating the required quantities for the 729 configurations of this benchmark. First, S N calculations were performed using fully symmetric angular quadratures and high-order diamond differencing for spatial discretization. To compare S N results with those of another deterministic method, the method of characteristics (MoC) was also considered for this benchmark. Comparisons between reference solutions, S N and MoC results illustrate the advantages and drawbacks of each methods for this 3-D transport problem.

  15. Compilation of field-scale caisson data on solute transport in the unsaturated zone

    International Nuclear Information System (INIS)

    Polzer, W.L.; Essington, E.H.; Fuentes, H.R.; Nyhan, J.W.

    1986-11-01

    Los Alamos National Laboratory has conducted technical support studies to assess siting requirements mandated by Nuclear Regulatory Commission in 10 CFR Part 61. Field-scale transport studies were conducted under unsaturated moisture conditions and under steady and unsteady flow conditions in large caissons located and operated in a natural (field) environment. Moisture content, temperature, flow rate, base-line chemical, tracer influent, and tracer breakthrough data collected during tracer migration studies in the caisson are compiled in tables and graphs. Data suggest that the imposition of a period of drainage (influent solution flow was stopped) may cause an increase in tracer concentration in the soil solution at various sampling points in the caisson. Evaporation during drainage and diffusion of the tracers from immobile to mobile water are two phenomena that could explain the increase. Data also suggest that heterogeneity of sorption sites may increase the variability in transport of sorbing tracers compared with nonsorbing tracers

  16. Presentation of some methods for the solution of the monoenergetic neutrons transport equation

    International Nuclear Information System (INIS)

    Valle G, E. del.

    1978-01-01

    The neutrons transport theory problems whose solution has been reached were collected in order to show that the transport equation is so complicated that different techniques were developed so as to give approximative numerical solutions to problems concerning the practical application. Such a technique, which had not been investigated in the literature dealing with these problems, is described here. The results which were obtained through this technique in undimensional problems of criticity are satisfactory and speaking in a conceptual way this method is extremely simple because it times. There is no limitation to deal with problems related neutrons sources with an arbitrary distribution and in principle the application of this technique can be extended to unhomogeneous environments. (author)

  17. Coupled Spatio-Temporal Patterns of Solute Transport, Metabolism and Nutrient Uptake in Streams

    Science.gov (United States)

    Kurz, M. J.; Schmidt, C.

    2017-12-01

    Slower flow velocities and longer residence times within stream transient storage (TS) zones facilitate interaction between solutes and microbial communities, potentially increasing local rates of metabolic activity. Multiple factors, including channel morphology and substrate, variable hydrology, and seasonal changes in biological and physical parameters, result in changes in the solute transport dynamics and reactivity of TS zones over time and space. These changes would be expected to, in turn, influence rates of whole-stream ecosystem functions such as metabolism and nutrient uptake. However, the linkages between solute transport and ecosystem functioning within TS zones, and the contribution of TS zones to whole-stream functioning, are not always so straight forward. This may be due, in part, to methodological challenges. In this study we investigated the influence of stream channel hydro-morphology and substrate type on reach (103 m) and sub-reach (102 m) scale TS and ecosystem functioning. Patterns in solute transport, metabolism and nitrate uptake were tracked from April through October in two contrasting upland streams using several methods. The two streams, located in the Harz Mountains, Germany, are characterized by differing size (0.02 vs. 0.3 m3/s), dominant stream channel substrate (bedrock vs. alluvium) and sub-reach morphology (predominance of pools, riffles and glides). Solute transport parameters and respiration rates at the reach and sub-reach scale were estimated monthly from coupled pulse injections of the reactive tracer resazurin (Raz) and conservative tracers uranine and salt. Raz, a weakly fluorescent dye, irreversibly transforms to resorufin (Rru) under mildly reducing conditions, providing a proxy for aerobic respiration. Daily rates of primary productivity, respiration and nitrate retention at the reach scale were estimated using the diel cycles in dissolved oxygen and nitrate concentrations measured by in-situ sensors. Preliminary

  18. A parallel multi-domain solution methodology applied to nonlinear thermal transport problems in nuclear fuel pins

    Energy Technology Data Exchange (ETDEWEB)

    Philip, Bobby, E-mail: philipb@ornl.gov [Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, TN 37831 (United States); Berrill, Mark A.; Allu, Srikanth; Hamilton, Steven P.; Sampath, Rahul S.; Clarno, Kevin T. [Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, TN 37831 (United States); Dilts, Gary A. [Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM 87545 (United States)

    2015-04-01

    This paper describes an efficient and nonlinearly consistent parallel solution methodology for solving coupled nonlinear thermal transport problems that occur in nuclear reactor applications over hundreds of individual 3D physical subdomains. Efficiency is obtained by leveraging knowledge of the physical domains, the physics on individual domains, and the couplings between them for preconditioning within a Jacobian Free Newton Krylov method. Details of the computational infrastructure that enabled this work, namely the open source Advanced Multi-Physics (AMP) package developed by the authors is described. Details of verification and validation experiments, and parallel performance analysis in weak and strong scaling studies demonstrating the achieved efficiency of the algorithm are presented. Furthermore, numerical experiments demonstrate that the preconditioner developed is independent of the number of fuel subdomains in a fuel rod, which is particularly important when simulating different types of fuel rods. Finally, we demonstrate the power of the coupling methodology by considering problems with couplings between surface and volume physics and coupling of nonlinear thermal transport in fuel rods to an external radiation transport code.

  19. Magnetic Modulation of the Transport of Organophilic Solutes through Supported Magnetic Ionic Liquid Membranes.

    Czech Academy of Sciences Publication Activity Database

    Daniel, C.L.; Rubio, A.M.; Sebastião, P.J.; Afonso, C.A.M.; Storch, Jan; Izák, Pavel; Portugal, C.A.M.; Crespo, J.G.

    2016-01-01

    Roč. 505, MAY 1 (2016), s. 36-43 ISSN 0376-7388 R&D Projects: GA ČR(CZ) GAP106/12/0569 Grant - others:ERANET(PT) ERA-CHEM/0001/2008; EUI(ES) 2008- 03857; FCT-MCTES(PT) SFRH/BD/81552/2011 Institutional support: RVO:67985858 Keywords : magnetic ionic liquids (MILs) * solute transport modulation * magnetic field Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 6.035, year: 2016

  20. Bounds and maximum principles for the solution of the linear transport equation

    International Nuclear Information System (INIS)

    Larsen, E.W.

    1981-01-01

    Pointwise bounds are derived for the solution of time-independent linear transport problems with surface sources in convex spatial domains. Under specified conditions, upper bounds are derived which, as a function of position, decrease with distance from the boundary. Also, sufficient conditions are obtained for the existence of maximum and minimum principles, and a counterexample is given which shows that such principles do not always exist

  1. Diffusion Dominant Solute Transport Modelling In Deep Repository Under The Effect of Emplacement Media Degradation - 13285

    International Nuclear Information System (INIS)

    Kwong, S.; Jivkov, A.P.

    2013-01-01

    Deep geologic disposal of high activity and long-lived radioactive waste is being actively considered and pursued in many countries, where low permeability geological formations are used to provide long term waste contaminant with minimum impact to the environment and risk to the biosphere. A multi-barrier approach that makes use of both engineered and natural barriers (i.e. geological formations) is often used to further enhance the containment performance of the repository. As the deep repository system subjects to a variety of thermo-hydro-chemo-mechanical (THCM) effects over its long 'operational' lifespan (e.g. 0.1 to 1.0 million years, the integrity of the barrier system will decrease over time (e.g. fracturing in rock or clay)). This is broadly referred as media degradation in the present study. This modelling study examines the effects of media degradation on diffusion dominant solute transport in fractured media that are typical of deep geological environment. In particular, reactive solute transport through fractured media is studied using a 2-D model, that considers advection and diffusion, to explore the coupled effects of kinetic and equilibrium chemical processes, while the effects of degradation is studied using a pore network model that considers the media diffusivity and network changes. Model results are presented to demonstrate the use of a 3D pore-network model, using a novel architecture, to calculate macroscopic properties of the medium such as diffusivity, subject to pore space changes as the media degrade. Results from a reactive transport model of a representative geological waste disposal package are also presented to demonstrate the effect of media property change on the solute migration behaviour, illustrating the complex interplay between kinetic biogeochemical processes and diffusion dominant transport. The initial modelling results demonstrate the feasibility of a coupled modelling approach (using pore-network model and reactive

  2. [Changes induced by hypertonic solutions in the transportation of calcium by the cardiac reticular sarcoplasma].

    Science.gov (United States)

    Sierra, M; Holguín, J A

    1979-01-01

    In the sarcoplasmic reticulum of the myocardium, celular organell which function is to regulate the cytoplasmic concentration of calcium in contraction and relaxation, we have studied the effect of hypertonic solutions of sucrose between 1 and 6.96 times the normal tonicity in order to observe the behavior of the internal linked or free calcium of this structure, as well as to prove the hypothesis that hypertonic solutions encourage the calcium exit of the sarcoplasmatic reticulum with the resulting signs of contractures. The following results were obtained: 1. The ATP hydrolisis and calcium transport rate are 14% and 90% respectively of the maximum speeds of 10(-5) M in calcium, while for concentrations of 10(-7) M or ess of the said cation, the transport rates and the ATPase do not reach 5% of the maximum values. 2. Between 1 and 2.54 times of the normal tonicity the calcium uptake remains between 400 and 500 nmoles of calcium/mg protein/min, the transported amount of calcium varies between 14 and 16 nmoles/mg protein and the rate of the ATP hydrolysis increases a 37% to 0.4 M in sucrose. 3. Between 0.4 and 1.2 M in sucrose of 2.54 to 6.96 times the isotonicity, the calcium transport rate velocity as well as the ATP hydrolisis are strongly inhibited. The vesicles volume minimizes and the amount of linked calcium remains within the control values, proving that the capacity of linking this cathion is independent from sarcoplasmic reticulum volume. These results show that the sarcoplasmic reticulum is involved in the contractures induced by hypertonic solutions in intact cells, since the osmolarity increase produces changes of volume which results in a decrease of the calcium transportation velocity or in an increase of the exit of said cathion.

  3. Upscaling solute transport in naturally fractured porous media with the continuous time random walk method

    Energy Technology Data Exchange (ETDEWEB)

    Geiger, S.; Cortis, A.; Birkholzer, J.T.

    2010-04-01

    Solute transport in fractured porous media is typically 'non-Fickian'; that is, it is characterized by early breakthrough and long tailing and by nonlinear growth of the Green function-centered second moment. This behavior is due to the effects of (1) multirate diffusion occurring between the highly permeable fracture network and the low-permeability rock matrix, (2) a wide range of advection rates in the fractures and, possibly, the matrix as well, and (3) a range of path lengths. As a consequence, prediction of solute transport processes at the macroscale represents a formidable challenge. Classical dual-porosity (or mobile-immobile) approaches in conjunction with an advection-dispersion equation and macroscopic dispersivity commonly fail to predict breakthrough of fractured porous media accurately. It was recently demonstrated that the continuous time random walk (CTRW) method can be used as a generalized upscaling approach. Here we extend this work and use results from high-resolution finite element-finite volume-based simulations of solute transport in an outcrop analogue of a naturally fractured reservoir to calibrate the CTRW method by extracting a distribution of retention times. This procedure allows us to predict breakthrough at other model locations accurately and to gain significant insight into the nature of the fracture-matrix interaction in naturally fractured porous reservoirs with geologically realistic fracture geometries.

  4. An Overview of Problems and Solutions for Urban Freight Transport in Brazilian Cities

    Directory of Open Access Journals (Sweden)

    Leise K. Oliveira

    2018-04-01

    Full Text Available Urban freight transport is a challenge for Brazilian cities due to the lack of adequate planning for freight flow movement. Public managers also show negligence and a lack of awareness when dealing with urban logistics. Decision-support data on urban freight transport are still scarce, despite being of fundamental value to economic development. With this in mind, this paper presents problems and solutions regarding urban freight transport in Brazilian cities. Data were obtained through a survey conducted in nine cities and analysed by means of descriptive statistics and the successive intervals method. Additionally, a cluster analysis was performed to identify patterns regarding the typical characteristics of each city in order to compare and generalise the perception of retailers regarding problems and solutions at the national level. The results indicate divergent opinions among retailers from different cities, even from cities with similar socioeconomic profiles and urban dynamics. The municipalities which demonstrated the most similarities were (i Betim and Niteroi, in the Southeast of Brazil; (ii Palmas and Quixada, in the North and Northeast, respectively; and (iii Palmas and Caruaru, also in the North and Northeast. The results reinforce the importance of studying the local context and involving stakeholders in the process of planning urban logistics solutions.

  5. Regional flow and solute transport modeling for site suitability. Part I

    International Nuclear Information System (INIS)

    Rowe, J.; Miller, I.

    1979-12-01

    The nature of regional flow systems in large sedimentary basins will largely determine the effectiveness of regional flow as a barrier to radionuclide escape from deep geologic repositories. The purpose of the work reported herein and the proposed future work is to develop a methodology for evaluating regional flow barriers by using numerical models. The Williston Basin was chosen as an archetype case for the regional modeling study. However, due to the simplified nature of the study, the results are not meant to represent the behavior of a repository actually placed within the Williston Basin. The major components of this Phase I study are: (1) assembly and reduction of available data; (2) formulation of a simplified geohydrologic model; (3) computer simulation of fluid flow; and (4) computer simulation of solute transport. As of this report, the first two items are essentially completed. Computer simulation of fluid flow will require some revision and further study, which will be done in the second phase of this study. Computer simulation of solute transport has been considered only on a very preliminary basis. Important conclusions of this Phase I study are as follows. Assembly and reduction of data require an extensive work effort. Generally, the parameters describing fluid flow are poorly known on a regional basis and those describing solute transport are unknown

  6. Regional flow and solute transport modeling for site suitability. Part I

    Energy Technology Data Exchange (ETDEWEB)

    Rowe, J.; Miller, I.

    1979-12-01

    The nature of regional flow systems in large sedimentary basins will largely determine the effectiveness of regional flow as a barrier to radionuclide escape from deep geologic repositories. The purpose of the work reported herein and the proposed future work is to develop a methodology for evaluating regional flow barriers by using numerical models. The Williston Basin was chosen as an archetype case for the regional modeling study. However, due to the simplified nature of the study, the results are not meant to represent the behavior of a repository actually placed within the Williston Basin. The major components of this Phase I study are: (1) assembly and reduction of available data; (2) formulation of a simplified geohydrologic model; (3) computer simulation of fluid flow; and (4) computer simulation of solute transport. As of this report, the first two items are essentially completed. Computer simulation of fluid flow will require some revision and further study, which will be done in the second phase of this study. Computer simulation of solute transport has been considered only on a very preliminary basis. Important conclusions of this Phase I study are as follows. Assembly and reduction of data require an extensive work effort. Generally, the parameters describing fluid flow are poorly known on a regional basis and those describing solute transport are unknown.

  7. Solution and study of nodal neutron transport equation applying the LTSN-DiagExp method

    International Nuclear Information System (INIS)

    Hauser, Eliete Biasotto; Pazos, Ruben Panta; Vilhena, Marco Tullio de; Barros, Ricardo Carvalho de

    2003-01-01

    In this paper we report advances about the three-dimensional nodal discrete-ordinates approximations of neutron transport equation for Cartesian geometry. We use the combined collocation method of the angular variables and nodal approach for the spatial variables. By nodal approach we mean the iterated transverse integration of the S N equations. This procedure leads to the set of one-dimensional averages angular fluxes in each spatial variable. The resulting system of equations is solved with the LTS N method, first applying the Laplace transform to the set of the nodal S N equations and then obtained the solution by symbolic computation. We include the LTS N method by diagonalization to solve the nodal neutron transport equation and then we outline the convergence of these nodal-LTS N approximations with the help of a norm associated to the quadrature formula used to approximate the integral term of the neutron transport equation. (author)

  8. Verification of Monte Carlo transport codes by activation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Chetvertkova, Vera

    2012-12-18

    With the increasing energies and intensities of heavy-ion accelerator facilities, the problem of an excessive activation of the accelerator components caused by beam losses becomes more and more important. Numerical experiments using Monte Carlo transport codes are performed in order to assess the levels of activation. The heavy-ion versions of the codes were released approximately a decade ago, therefore the verification is needed to be sure that they give reasonable results. Present work is focused on obtaining the experimental data on activation of the targets by heavy-ion beams. Several experiments were performed at GSI Helmholtzzentrum fuer Schwerionenforschung. The interaction of nitrogen, argon and uranium beams with aluminum targets, as well as interaction of nitrogen and argon beams with copper targets was studied. After the irradiation of the targets by different ion beams from the SIS18 synchrotron at GSI, the γ-spectroscopy analysis was done: the γ-spectra of the residual activity were measured, the radioactive nuclides were identified, their amount and depth distribution were detected. The obtained experimental results were compared with the results of the Monte Carlo simulations using FLUKA, MARS and SHIELD. The discrepancies and agreements between experiment and simulations are pointed out. The origin of discrepancies is discussed. Obtained results allow for a better verification of the Monte Carlo transport codes, and also provide information for their further development. The necessity of the activation studies for accelerator applications is discussed. The limits of applicability of the heavy-ion beam-loss criteria were studied using the FLUKA code. FLUKA-simulations were done to determine the most preferable from the radiation protection point of view materials for use in accelerator components.

  9. Thermally Cross-Linkable Hole Transport Materials for Solution Processed Phosphorescent OLEDs

    Science.gov (United States)

    Kim, Beom Seok; Kim, Ohyoung; Chin, Byung Doo; Lee, Chil Won

    2018-04-01

    Materials for unique fabrication of a solution-processed, multi-layered organic light-emitting diode (OLED) were developed. Preparation of a hole transport layer with a thermally cross-linkable chemical structure, which can be processed to form a thin film and then transformed into an insoluble film by using an amine-alcohol condensation reaction with heat treatment, was investigated. Functional groups, such as triplenylamine linked with phenylcarbazole or biphenyl, were employed in the chemical structure of the hole transport layer in order to maintain high triplet energy properties. When phenylcarbazole or biphenyl compounds continuously react with triphenylamine under acid catalysis, a chemically stable thin film material with desirable energy-level properties for a blue OLED could be obtained. The prepared hole transport materials showed excellent surface roughness and thermal stability in comparison with the commercial reference material. On the solution-processed model hole transport layer, we fabricated a device with a blue phosphorescent OLED by using sequential vacuum deposition. The maximum external quantum, 19.3%, was improved by more than 40% over devices with the commercial reference material (11.4%).

  10. Numerical investigations of solute transport in bimodal porous media under dynamic boundary conditions

    Science.gov (United States)

    Cremer, Clemens; Neuweiler, Insa; Bechtold, Michel; Vanderborght, Jan

    2016-04-01

    Quantification of flow and solute transport in the shallow subsurface adjacent to the atmosphere is decisive to prevent groundwater pollution and conserve groundwater quality, to develop successful remediation strategies and to understand nutrient cycling. In nature, due to erratic precipitation-evaporation patterns, soil moisture content and related hydraulic conductivity in the vadose zone are not only variable in space but also in time. Flow directions and flow paths locally change between precipitation and evaporation periods. This makes the identification and description of solute transport processes in the vadose zone a complex problem. Recent studies (Lehmann and Or, 2009; Bechtold et al., 2011a) focused on the investigation of upward transport of solutes during evaporation in heterogeneous soil columns, where heterogeneity was introduced by a sharp vertical material interface between two types of sand. Lateral solute transport through the interface in both (lateral) directions was observed at different depths of the investigated soil columns. Following recent approaches, we conduct two-dimensional numerical simulations in a similar setup which is composed of two sands with a sharp vertical material interface. The investigation is broadened from the sole evaporation to combined precipitation-evaporation cycles in order to quantify transport processes resulting from the combined effects of heterogeneous soil structure and dynamic flow conditions. Simulations are performed with a coupled finite volume and random walk particle tracking algorithm (Ippisch et al., 2006; Bechtold et al., 2011b). By comparing scenarios with cyclic boundary conditions and stationary counterparts with the same net flow rate, we found that duration and intensity of precipitation and evaporation periods potentially have an influence on lateral redistribution of solutes and thus leaching rates. Whether or not dynamic boundary conditions lead to significant deviations in the transport

  11. Representing solute transport through the multi-barrier disposal system by simplified concepts

    International Nuclear Information System (INIS)

    Poteri, A.; Nordman, H.; Pulkkanen, V-M.; Kekaelaeinen, P.; Hautojaervi, A.

    2012-02-01

    The repository system chosen in Finland for spent nuclear fuel is composed of multiple successive transport barriers. If a waste canister is leaking, this multi-barrier system retards and limits the release rates of radionuclides into the biosphere. Analysis of radionuclide migration in the previous performance assessments has largely been based on numerical modelling of the repository system. The simplified analytical approach introduced here provides a tool to analyse the performance of the whole system using simplified representations of the individual transport barriers. This approach is based on the main characteristics of the individual barriers and on the generic nature of the coupling between successive barriers. In the case of underground repository the mass transfer between successive transport barriers is strongly restricted by the interfaces between barriers leading to well-mixed conditions in these barriers. The approach here simplifies the barrier system so that it can be described with a very simple compartment model, where each barrier is represented by a single, or in the case of buffer, by not more than two compartments. This system of compartments could be solved in analogy with a radioactive decay chain. The model of well mixed compartments lends itself to a very descriptive way to represent and analyse the barrier system because the relative efficiency of the different barriers in hindering transport of solutes can be parameterised by the solutes half-times in the corresponding compartments. In a real repository system there will also be a delay between the start of the inflow and the start of the outflow from the barrier. This delay can be important for the release rates of the short lived and sorbing radionuclides, and it was also included in the simplified representation of the barrier system. In a geological multi-barrier system, spreading of the outflowing release pulse is often governed by the typical behaviour of one transport barrier

  12. Representing solute transport through the multi-barrier disposal system by simplified concepts

    Energy Technology Data Exchange (ETDEWEB)

    Poteri, A.; Nordman, H.; Pulkkanen, V-M. [VTT Technical Research Centre of Finland, Espoo (Finland); Kekaelaeinen, P. [Jyvaeskylae Univ. (Finland). Dept. pf Physics; Hautojaervi, A.

    2012-02-15

    The repository system chosen in Finland for spent nuclear fuel is composed of multiple successive transport barriers. If a waste canister is leaking, this multi-barrier system retards and limits the release rates of radionuclides into the biosphere. Analysis of radionuclide migration in the previous performance assessments has largely been based on numerical modelling of the repository system. The simplified analytical approach introduced here provides a tool to analyse the performance of the whole system using simplified representations of the individual transport barriers. This approach is based on the main characteristics of the individual barriers and on the generic nature of the coupling between successive barriers. In the case of underground repository the mass transfer between successive transport barriers is strongly restricted by the interfaces between barriers leading to well-mixed conditions in these barriers. The approach here simplifies the barrier system so that it can be described with a very simple compartment model, where each barrier is represented by a single, or in the case of buffer, by not more than two compartments. This system of compartments could be solved in analogy with a radioactive decay chain. The model of well mixed compartments lends itself to a very descriptive way to represent and analyse the barrier system because the relative efficiency of the different barriers in hindering transport of solutes can be parameterised by the solutes half-times in the corresponding compartments. In a real repository system there will also be a delay between the start of the inflow and the start of the outflow from the barrier. This delay can be important for the release rates of the short lived and sorbing radionuclides, and it was also included in the simplified representation of the barrier system. In a geological multi-barrier system, spreading of the outflowing release pulse is often governed by the typical behaviour of one transport barrier

  13. An experiment on multibubble sonoluminescence spectra in sodium chloride solution

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhan; XU JunFeng; HUANG Wei; CHEN WeiZhong; MIAO GuoQing

    2008-01-01

    We investigated experimentally the spectra of MBSL in sodium chloride water solution with krypton as dissolved gas. We observed and compared the spectra of hydroxyl ion at 310 nm and that of sodium atom at 589 nm. It has been found that under the same experimental condition, the intensity of sodium atom spectra is obviously higher than that of the hydroxyl ion spectra, and is more sensitive to the experimental condition. The krypton content, the concentration of sodium chloride solution, and the driving sound pressure obviously affect the spectra intensity in certain range.

  14. The Method of Manufactured Solutions for RattleSnake A SN Radiation Transport Solver Inside the MOOSE Framework

    International Nuclear Information System (INIS)

    Wang, Yaqi

    2012-01-01

    The Method of Manufactured Solutions (MMS) is an accepted technique to verify that a numerical discretization for the radiation transport equation has been implemented correctly. This technique offers a few advantages over other methods such as benchmark problems or analytical solutions. The solution can be manufactured such that properties for the angular flux are either stressed or preserved. For radiation transport, these properties can include desired smoothness, positiveness and arbitrary order of anisotropy in angle. Another advantage is that the angular flux solution can be manufactured for multidimensional problems where analytical solutions are difficult to obtain in general.

  15. Mechanisms to explain the reverse perivascular transport of solutes out of the brain.

    Science.gov (United States)

    Schley, D; Carare-Nnadi, R; Please, C P; Perry, V H; Weller, R O

    2006-02-21

    Experimental studies and observations in the human brain indicate that interstitial fluid and solutes, such as amyloid-beta (Abeta), are eliminated from grey matter of the brain along pericapillary and periarterial pathways. It is unclear, however, what constitutes the motive force for such transport within blood vessel walls, which is in the opposite direction to blood flow. In this paper the potential for global pressure differences to achieve such transport are considered. A mathematical model is constructed in order to test the hypothesis that perivascular drainage of interstitial fluid and solutes out of brain tissue is driven by pulsations of the blood vessel walls. Here it is assumed that drainage occurs through a thin layer between astrocytes and endothelial cells or between smooth muscle cells. The model suggests that, during each pulse cycle, there are periods when fluid and solutes are driven along perivascular spaces in the reverse direction to the flow of blood. It is shown that successful drainage may depend upon some attachment of solutes to the lining of the perivascular space, in order to produce a valve-like effect, although an alternative without this requirement is also postulated. Reduction in pulse amplitude, as in ageing cerebral vessels, would prolong the attachment time, encourage precipitation of Abeta peptides in vessel walls, and impair elimination of Abeta from the brain. These factors may play a role in the pathogenesis of cerebral amyloid angiopathy and in the accumulation of Abeta in the brain in Alzheimer's disease.

  16. A lattice Boltzmann model for solute transport in open channel flow

    Science.gov (United States)

    Wang, Hongda; Cater, John; Liu, Haifei; Ding, Xiangyi; Huang, Wei

    2018-01-01

    A lattice Boltzmann model of advection-dispersion problems in one-dimensional (1D) open channel flows is developed for simulation of solute transport and pollutant concentration. The hydrodynamics are calculated based on a previous lattice Boltzmann approach to solving the 1D Saint-Venant equations (LABSVE). The advection-dispersion model is coupled with the LABSVE using the lattice Boltzmann method. Our research recovers the advection-dispersion equations through the Chapman-Enskog expansion of the lattice Boltzmann equation. The model differs from the existing schemes in two points: (1) the lattice Boltzmann numerical method is adopted to solve the advection-dispersion problem by meso-scopic particle distribution; (2) and the model describes the relation between discharge, cross section area and solute concentration, which increases the applicability of the water quality model in practical engineering. The model is verified using three benchmark tests: (1) instantaneous solute transport within a short distance; (2) 1D point source pollution with constant velocity; (3) 1D point source pollution in a dam break flow. The model is then applied to a 50-year flood point source pollution accident on the Yongding River, which showed good agreement with a MIKE 11 solution and gauging data.

  17. Benchmarking the invariant embedding method against analytical solutions in model transport problems

    International Nuclear Information System (INIS)

    Malin, Wahlberg; Imre, Pazsit

    2005-01-01

    The purpose of this paper is to demonstrate the use of the invariant embedding method in a series of model transport problems, for which it is also possible to obtain an analytical solution. Due to the non-linear character of the embedding equations, their solution can only be obtained numerically. However, this can be done via a robust and effective iteration scheme. In return, the domain of applicability is far wider than the model problems investigated in this paper. The use of the invariant embedding method is demonstrated in three different areas. The first is the calculation of the energy spectrum of reflected (sputtered) particles from a multiplying medium, where the multiplication arises from recoil production. Both constant and energy dependent cross sections with a power law dependence were used in the calculations. The second application concerns the calculation of the path length distribution of reflected particles from a medium without multiplication. This is a relatively novel and unexpected application, since the embedding equations do not resolve the depth variable. The third application concerns the demonstration that solutions in an infinite medium and a half-space are interrelated through embedding-like integral equations, by the solution of which the reflected flux from a half-space can be reconstructed from solutions in an infinite medium or vice versa. In all cases the invariant embedding method proved to be robust, fast and monotonically converging to the exact solutions. (authors)

  18. On the spectral analysis of iterative solutions of the discretized one-group transport equation

    International Nuclear Information System (INIS)

    Sanchez, Richard

    2004-01-01

    We analyze the Fourier-mode technique used for the spectral analysis of iterative solutions of the one-group discretized transport equation. We introduce a direct spectral analysis for the iterative solution of finite difference approximations for finite slabs composed of identical layers, providing thus a complementary analysis that is more appropriate for reactor applications. Numerical calculations for the method of characteristics and with the diamond difference approximation show the appearance of antisymmetric modes generated by the iteration on boundary data. We have also utilized the discrete Fourier transform to compute the spectrum for a periodic slab containing N identical layers and shown that at the limit N → ∞ one obtains the familiar Fourier-mode solution

  19. The composite water and solute transport of barley (Hordeum vulgare) roots: effect of suberized barriers.

    Science.gov (United States)

    Ranathunge, Kosala; Kim, Yangmin X; Wassmann, Friedrich; Kreszies, Tino; Zeisler, Viktoria; Schreiber, Lukas

    2017-03-01

    Roots have complex anatomical structures, and certain localized cell layers develop suberized apoplastic barriers. The size and tightness of these barriers depend on the growth conditions and on the age of the root. Such complex anatomical structures result in a composite water and solute transport in roots. Development of apoplastic barriers along barley seminal roots was detected using various staining methods, and the suberin amounts in the apical and basal zones were analysed using gas chromatography-mass spectometry (GC-MS). The hydraulic conductivity of roots ( Lp r ) and of cortical cells ( Lp c ) was measured using root and cell pressure probes. When grown in hydroponics, barley roots did not form an exodermis, even at their basal zones. However, they developed an endodermis. Endodermal Casparian bands first appeared as 'dots' as early as at 20 mm from the apex, whereas a patchy suberin lamellae appeared at 60 mm. The endodermal suberin accounted for the total suberin of the roots. The absolute amount in the basal zone was significantly higher than in the apical zone, which was inversely proportional to the Lp r . Comparison of Lp r and Lp c suggested that cell to cell pathways dominate for water transport in roots. However, the calculation of Lp r from Lp c showed that at least 26 % of water transport occurs through the apoplast. Roots had different solute permeabilities ( P sr ) and reflection coefficients ( σ sr ) for the solutes used. The σ sr was below unity for the solutes, which have virtually zero permeability for semi-permeable membranes. Suberized endodermis significantly reduces Lp r of seminal roots. The water and solute transport across barley roots is composite in nature and they do not behave like ideal osmometers. The composite transport model should be extended by adding components arranged in series (cortex, endodermis) in addition to the currently included components arranged in parallel (apoplastic, cell to cell pathways). © The

  20. Cadmium uptake from solution by plants and its transport from roots to shoots

    Energy Technology Data Exchange (ETDEWEB)

    Jarvis, S.C.; Jones, L.H.P.; Hopper, M.J.

    1976-02-01

    The uptake of cadmium by the roots of plants, and its transport to shoots was examined using solution culture. Uptake by the roots of perennial ryegrass over a period of 4 hours from an aqueous solution containing 0.25 ppm cadmium as CdCl/sub 2/ was (i) enhanced by killing the roots and (ii) depressed when Ca/sup 2 +/, Mn/sup 2 +/ or Zn/sup 2 +/ were added to the solution. The distribution of cadmium between the roots and shoots of 23 species was examined at 4 days after a single, 3-day exposure to a nutrient solution containing 0.01 ppm added Cd. In all except 3 species, i.e. kale, lettuce and watercress, more than 50% of that taken up was retained in the shoot, and in fibrous roots of fodder beet, parsnip, carrot and radish it was greater than in the swollen storage roots. When perennial ryegrass was similarly exposed to solutions containing 0.01, 0.05, and 0.25 ppm added cadmium, uptake, as measured at 3 days after adding cadmium, increased with increasing rates of addition, but the proportion retained in the roots was constant (approximately 88%). There was no further transport from roots to shoots during the next 21 days, with the result that the concentration in the shoots decreased progressively with increasing growth. It is concluded that although the roots of several species can take up large quantities of cadmium from solution there are mechanisms which may restrict the movement of cadmium through plants, and thus to animals. 21 references, 7 tables.

  1. Fibrin structural and diffusional analysis suggests that fibers are permeable to solute transport.

    Science.gov (United States)

    Leonidakis, Kimon Alexandros; Bhattacharya, Pinaki; Patterson, Jennifer; Vos, Bart E; Koenderink, Gijsje H; Vermant, Jan; Lambrechts, Dennis; Roeffaers, Maarten; Van Oosterwyck, Hans

    2017-01-01

    Fibrin hydrogels are promising carrier materials in tissue engineering. They are biocompatible and easy to prepare, they can bind growth factors and they can be prepared from a patient's own blood. While fibrin structure and mechanics have been extensively studied, not much is known about the relation between structure and diffusivity of solutes within the network. This is particularly relevant for solutes with a size similar to that of growth factors. A novel methodological approach has been used in this study to retrieve quantitative structural characteristics of fibrin hydrogels, by combining two complementary techniques, namely confocal fluorescence microscopy with a fiber extraction algorithm and turbidity measurements. Bulk rheological measurements were conducted to determine the impact of fibrin hydrogel structure on mechanical properties. From these measurements it can be concluded that variations in the fibrin hydrogel structure have a large impact on the rheological response of the hydrogels (up to two orders of magnitude difference in storage modulus) but only a moderate influence on the diffusivity of dextran solutes (up to 25% difference). By analyzing the diffusivity measurements by means of the Ogston diffusion model we further provide evidence that individual fibrin fibers can be semi-permeable to solute transport, depending on the average distance between individual protofibrils. This can be important for reducing mass transport limitations, for modulating fibrinolysis and for growth factor binding, which are all relevant for tissue engineering. Fibrin is a natural biopolymer that has drawn much interest as a biomimetic carrier in tissue engineering applications. We hereby use a novel combined approach for the structural characterization of fibrin networks based on optical microscopy and light scattering methods that can also be applied to other fibrillar hydrogels, like collagen. Furthermore, our findings on the relation between solute transport

  2. Modelling transport of water and solutes in future wetlands in Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Vikstroem, Maria; Gustafsson, Lars-Goeran [DHI Water and Environment AB, Vaexjoe (Sweden)

    2006-03-15

    been analyzed. Results from the transport modelling show that a solute in the bedrock is transported quickly towards the peat surface in discharge areas for Bolundsfjaerden. After around 10 years, a stationary condition is reached. For the recharge area that develops in large parts of the mire, the solute is transported through horizontal dispersion, which results in much lower concentrations. The solute concentration is at the lowest where the overland water pressure is at the highest close to the south western inlet. Puttan has a vertical flow pattern that differs from Bolundsfjaerden. The pressure from water on the peat surface is considerably lower and for a major part of the year Puttan is a discharge area with an upwards flow direction. The spatial distribution of solutes is more even over the surface than for Bolundsfjaerden, but higher concentrations are found around today's shoreline. A solute reaching the wetland through surface runoff is transported relatively slow through the mire at Bolundsfjaerden. Due to the recharge conditions, the solute is spread to the underlying soil layers. The vertical solute transport follows the discharge and recharge areas, where high concentrations, up to the source strength, are reached in major parts of the formation, while lower concentrations are reached in the discharge areas and underneath clay sediment.

  3. Modelling transport of water and solutes in future wetlands in Forsmark

    International Nuclear Information System (INIS)

    Vikstroem, Maria; Gustafsson, Lars-Goeran

    2006-03-01

    analyzed. Results from the transport modelling show that a solute in the bedrock is transported quickly towards the peat surface in discharge areas for Bolundsfjaerden. After around 10 years, a stationary condition is reached. For the recharge area that develops in large parts of the mire, the solute is transported through horizontal dispersion, which results in much lower concentrations. The solute concentration is at the lowest where the overland water pressure is at the highest close to the south western inlet. Puttan has a vertical flow pattern that differs from Bolundsfjaerden. The pressure from water on the peat surface is considerably lower and for a major part of the year Puttan is a discharge area with an upwards flow direction. The spatial distribution of solutes is more even over the surface than for Bolundsfjaerden, but higher concentrations are found around today's shoreline. A solute reaching the wetland through surface runoff is transported relatively slow through the mire at Bolundsfjaerden. Due to the recharge conditions, the solute is spread to the underlying soil layers. The vertical solute transport follows the discharge and recharge areas, where high concentrations, up to the source strength, are reached in major parts of the formation, while lower concentrations are reached in the discharge areas and underneath clay sediment

  4. Power transport to the poloidal divertor experiment scoop limiter

    International Nuclear Information System (INIS)

    Kugel, H.W.; Budny, R.; Fonck, R.

    1987-01-01

    Power transport to the Poloidal Divertor Experiment graphite scoop limiter was measured during both ohmic- and neutral-beam-heated discharges by observing its front face temperatures using an infrared camera. Measurements were made as a function of a plasma density, current, position, fueling mode, and heating power for both co- and counter-neutral beam injection. The measured thermal load on the scoop limiter was 25 to 50%. of the total plasma heating power. The measured peak front face midplane temperature was 1500 0 C, corresponding to a peak surface power density of 3 kW/cm/sup 2/. This power density implies an effective parallel power flow of 54 kW/cm/sup 2/ in agreement with the radial power distribution extrapolated from television Thomson scattering and calorimetry measurements

  5. Characterization of a novel organic solute transporter homologue from Clonorchis sinensis.

    Directory of Open Access Journals (Sweden)

    Yanyan Lu

    2018-04-01

    Full Text Available Clonorchis sinensis is a liver fluke that can dwell in the bile ducts of mammals. Bile acid transporters function to maintain the homeostasis of bile acids in C. sinensis, as they induce physiological changes or have harmful effects on C. sinensis survival. The organic solute transporter (OST transports mainly bile acid and belongs to the SLC51 subfamily of solute carrier transporters. OST plays a critical role in the recirculation of bile acids in higher animals. In this study, we cloned full-length cDNA of the 480-amino acid OST from C. sinensis (CsOST. Genomic analysis revealed 11 exons and nine introns. The CsOST protein had a 'Solute_trans_a' domain with 67% homology to Schistosoma japonicum OST. For further analysis, the CsOST protein sequence was split into the ordered domain (CsOST-N at the N-terminus and disordered domain (CsOST-C at the C-terminus. The tertiary structure of each domain was built using a threading-based method and determined by manual comparison. In a phylogenetic tree, the CsOST-N domain belonged to the OSTα and CsOST-C to the OSTβ clade. These two domains were more highly conserved with the OST α- and β-subunits at the structure level than at sequence level. These findings suggested that CsOST comprised the OST α- and β-subunits. CsOST was localized in the oral and ventral suckers and in the mesenchymal tissues abundant around the intestine, vitelline glands, uterus, and testes. This study provides fundamental data for the further understanding of homologues in other flukes.

  6. Characterization of a novel organic solute transporter homologue from Clonorchis sinensis

    Science.gov (United States)

    Dai, Fuhong; Lee, Ji-Yun; Pak, Jhang Ho; Sohn, Woon-Mok

    2018-01-01

    Clonorchis sinensis is a liver fluke that can dwell in the bile ducts of mammals. Bile acid transporters function to maintain the homeostasis of bile acids in C. sinensis, as they induce physiological changes or have harmful effects on C. sinensis survival. The organic solute transporter (OST) transports mainly bile acid and belongs to the SLC51 subfamily of solute carrier transporters. OST plays a critical role in the recirculation of bile acids in higher animals. In this study, we cloned full-length cDNA of the 480-amino acid OST from C. sinensis (CsOST). Genomic analysis revealed 11 exons and nine introns. The CsOST protein had a ‘Solute_trans_a’ domain with 67% homology to Schistosoma japonicum OST. For further analysis, the CsOST protein sequence was split into the ordered domain (CsOST-N) at the N-terminus and disordered domain (CsOST-C) at the C-terminus. The tertiary structure of each domain was built using a threading-based method and determined by manual comparison. In a phylogenetic tree, the CsOST-N domain belonged to the OSTα and CsOST-C to the OSTβ clade. These two domains were more highly conserved with the OST α- and β-subunits at the structure level than at sequence level. These findings suggested that CsOST comprised the OST α- and β-subunits. CsOST was localized in the oral and ventral suckers and in the mesenchymal tissues abundant around the intestine, vitelline glands, uterus, and testes. This study provides fundamental data for the further understanding of homologues in other flukes. PMID:29702646

  7. Groundwater and solute transport modeling at Hyporheic zone of upper part Citarum River

    Science.gov (United States)

    Iskandar, Irwan; Farazi, Hendy; Fadhilah, Rahmat; Purnandi, Cipto; Notosiswoyo, Sudarto

    2017-06-01

    Groundwater and surface water interaction is an interesting topic to be studied related to the water resources and environmental studies. The study of interaction between groundwater and river water at the Upper Part Citarum River aims to know the contribution of groundwater to the river or reversely and also solute transport of dissolved ions between them. Analysis of drill logs, vertical electrical sounding at the selected sections, measurement of dissolved ions, and groundwater modeling were applied to determine the flow and solute transport phenomena at the hyporheic zone. It showed the hyporheic zone dominated by silt and clay with hydraulic conductivity range from 10-4∼10-8 m/s. The groundwater flowing into the river with very low gradient and it shows that the Citarum River is a gaining stream. The groundwater modeling shows direct seepage of groundwater into the Citarum River is only 186 l/s, very small compared to the total discharge of the river. Total dissolved ions of the groundwater ranged from 200 to 480 ppm while the river water range from 200 to 2,000 ppm. Based on solute transport modeling it indicates dissolved ions dispersion of the Citarum River into groundwater may occur in some areas such as Bojongsoang-Dayeuh Kolot and Nanjung. This situation would increase the dissolved ions in groundwater in the region due to the contribution of the Citarum River. The results of the research can be a reference for further studies related to the mechanism of transport of the pollutants in the groundwater around the Citarum River.

  8. Capillary-Driven Solute Transport and Precipitation in Porous Media during Dry-Out

    Science.gov (United States)

    Ott, Holger; Andrew, Matthew; Blunt, Martin; Snippe, Jeroen

    2014-05-01

    The injection of dry or under-saturated gases or supercritical (SC) fluids into water bearing formations might lead to a formation dry-out in the vicinity of the injection well. The dry-out is caused by the evaporation/dissolution of formation water into the injected fluid and the subsequent transport of dissolved water in the injected fluid away from the injection well. Dry-out results in precipitation from solutes of the formation brine and consequently leads to a reduction of the rock's pore space (porosity) and eventually to a reduction of permeability near the injection well, or even to the loss of injectivity. Recently evidence has been found that the complexity of the pore space and the respective capillary driven solute transport plays a key role. While no effective-permeability (Keff) reduction was observed in a single-porosity sandstone, multi porosity carbonate rocks responded to precipitation with a strong reduction of Keff. The reason for the different response of Keff to salt precipitation is suspected to be in the exact location of the precipitate (solid salt) in the pore space. In this study, we investigate dry-out and salt precipitation due to supercritical CO2 injection in single and multi-porosity systems under near well-bore conditions. We image fluid saturation changes by means of μCT scanning during desaturation. We are able to observe capillary driven transport of the brine phase and the respective transport of solutes on the rock's pore scale. Finally we have access to the precipitated solid-salt phase and their distribution. The results can proof the thought models behind permeability porosity relationships K(φ) for injectivity modeling. The topic and the mechanisms we show are of general interest for drying processes in porous material such as soils and paper.

  9. High Fill-Factor Transport Experiments on the HCX

    International Nuclear Information System (INIS)

    Prost, L R; Seidl, P A; Lund, S M

    2004-01-01

    Heavy-ion induction linacs have application as drivers for high energy density physics studies and ultimately as drivers for inertial fusion energy. Experiments on the High-Current Experiment (HCX) at LBNL explore heavy-ion beam transport at high fill factors (i.e., the ratio of the maximum transverse extent of the beam to the physical aperture). The fill factor has a large impact on the cost of multi-beam induction accelerators, the 80% fill factor compared with 60% would reduce the cost of an HIF driver by about 1/3. With a coasting low-emittance 1 MeV K + beam, transport through ten electrostatic quadrupoles was achieved at high beam fill factor (80%) without observed emittance growth and with little beam loss ((le) 1%), even though the initial beam distribution is neither ideal nor in thermal equilibrium, see Figure. While 10 quadrupoles are too few for settling questions of emittance evolution in a long system, they are very relevant for studying the rapid initial evolution of the emittance and beam profile that is expected in the front end of an accelerator. Studies at higher fill factors are planned, so that the failure mode can be established. Good envelope control was achieved, suggesting that, in a longer lattice of similar design, rematching only every ten lattice periods (at 80% fill factor) will be sufficient. Agreement was reached between an improved envelope model and the data. Improvements to the model are: realistic quadrupole fringe fields based on 3D field calculations; quadrupole E z from the 3D lattice structure and corresponding radial focusing force; and corrections due to the grounded slit plates of the intercepting diagnostics that short out the self-field of the beam near those plates. We also find that understanding and controlling the time dependence of the envelope parameters is critical to achieving high fill factors, notably because of the injector and matching section dynamics

  10. Diffusion Dominant Solute Transport Modelling in Fractured Media Under Deep Geological Environment - 12211

    Energy Technology Data Exchange (ETDEWEB)

    Kwong, S. [National Nuclear Laboratory (United Kingdom); Jivkov, A.P. [Research Centre for Radwaste and Decommissioning and Modelling and Simulation Centre, University of Manchester (United Kingdom)

    2012-07-01

    Deep geologic disposal of high activity and long-lived radioactive waste is gaining increasing support in many countries, where suitable low permeability geological formation in combination with engineered barriers are used to provide long term waste contaminant and minimise the impacts to the environment and risk to the biosphere. This modelling study examines the solute transport in fractured media under low flow velocities that are relevant to a deep geological environment. In particular, reactive solute transport through fractured media is studied using a 2-D model, that considers advection and diffusion, to explore the coupled effects of kinetic and equilibrium chemical processes. The effects of water velocity in the fracture, matrix porosity and diffusion on solute transport are investigated and discussed. Some illustrative modelled results are presented to demonstrate the use of the model to examine the effects of media degradation on solute transport, under the influences of hydrogeological (diffusion dominant) and microbially mediated chemical processes. The challenges facing the prediction of long term degradation such as cracks evolution, interaction and coalescence are highlighted. The potential of a novel microstructure informed modelling approach to account for these effects is discussed, particularly with respect to investigating multiple phenomena impact on material performance. The GRM code is used to examine the effects of media degradation for a geological waste disposal package, under the combined hydrogeological (diffusion dominant) and chemical effects in low groundwater flow conditions that are typical of deep geological disposal systems. An illustrative reactive transport modelling application demonstrates the use of the code to examine the interplay of kinetic controlled biogeochemical reactive processes with advective and diffusive transport, under the influence of media degradation. The initial model results are encouraging which show the

  11. Immunohistochemical expression profiles of solute carrier transporters in alpha-fetoprotein-producing gastric cancer.

    Science.gov (United States)

    Shimakata, Takaaki; Kamoshida, Shingo; Kawamura, Jumpei; Ogane, Naoki; Kameda, Yoichi; Yanagita, Emmy; Itoh, Tomoo; Takeda, Risa; Naka, Ayano; Sakamaki, Kuniko; Hayashi, Yurie; Kuwao, Sadahito

    2016-11-01

    Alpha-fetoprotein (AFP)-producing gastric cancer (GC) is an aggressive tumour with high rates of liver metastasis and poor prognosis, and for which a validated chemotherapy regimen has not been established. Drug uptake by solute carrier (SLC) transporters is proposed as one of the mechanisms involved in sensitivity to chemotherapy. In this study, we aimed to develop important insights into effective chemotherapeutic regimens for AFP-producing GC. We evaluated immunohistochemically the expression levels of a panel of SLC transporters in 20 AFP-producing GCs and 130 conventional GCs. SLC transporters examined were human equilibrative nucleoside transporter 1 (hENT1), organic anion transporter 2 (OAT2), organic cation transporter (OCT) 2, OCT6 and organic anion-transporting polypeptide 1B3 (OATP1B3). The rates of high expression levels of hENT1 (hENT1 high ) and OAT2 (OAT2 high ) were statistically higher in AFP-producing GC, compared with conventional GC. When analysing hENT1 and OAT2 in combination, hENT1 high /OAT2 high was the most particular expression profile for AFP-producing GC, with a greater significance than hENT1 or OAT2 alone. However, no significant differences in OCT2, OCT6 or OATP1B3 levels were detected between AFP-producing and conventional GCs. However, immunoreactivity for hENT1, OAT2 and OCT6 tended to be increased in GC tissues compared with non-neoplastic epithelia. Because hENT1 and OAT2 are crucial for the uptake of gemcitabine and 5-fluorouracil, respectively, our results suggest that patients with AFP-producing GC could potentially benefit from gemcitabine/fluoropyrimidine combination chemotherapy. Increased expression of hENT1, OAT2 and OCT6 may also be associated with the progression of GC. © 2016 John Wiley & Sons Ltd.

  12. Modeling variably saturated multispecies reactive groundwater solute transport with MODFLOW-UZF and RT3D

    Science.gov (United States)

    Bailey, Ryan T.; Morway, Eric D.; Niswonger, Richard G.; Gates, Timothy K.

    2013-01-01

    A numerical model was developed that is capable of simulating multispecies reactive solute transport in variably saturated porous media. This model consists of a modified version of the reactive transport model RT3D (Reactive Transport in 3 Dimensions) that is linked to the Unsaturated-Zone Flow (UZF1) package and MODFLOW. Referred to as UZF-RT3D, the model is tested against published analytical benchmarks as well as other published contaminant transport models, including HYDRUS-1D, VS2DT, and SUTRA, and the coupled flow and transport modeling system of CATHY and TRAN3D. Comparisons in one-dimensional, two-dimensional, and three-dimensional variably saturated systems are explored. While several test cases are included to verify the correct implementation of variably saturated transport in UZF-RT3D, other cases are included to demonstrate the usefulness of the code in terms of model run-time and handling the reaction kinetics of multiple interacting species in variably saturated subsurface systems. As UZF1 relies on a kinematic-wave approximation for unsaturated flow that neglects the diffusive terms in Richards equation, UZF-RT3D can be used for large-scale aquifer systems for which the UZF1 formulation is reasonable, that is, capillary-pressure gradients can be neglected and soil parameters can be treated as homogeneous. Decreased model run-time and the ability to include site-specific chemical species and chemical reactions make UZF-RT3D an attractive model for efficient simulation of multispecies reactive transport in variably saturated large-scale subsurface systems.

  13. A computational model for simulating solute transport and oxygen consumption along the nephrons

    Science.gov (United States)

    Vallon, Volker; Edwards, Aurélie

    2016-01-01

    The goal of this study was to investigate water and solute transport, with a focus on sodium transport (TNa) and metabolism along individual nephron segments under differing physiological and pathophysiological conditions. To accomplish this goal, we developed a computational model of solute transport and oxygen consumption (QO2) along different nephron populations of a rat kidney. The model represents detailed epithelial and paracellular transport processes along both the superficial and juxtamedullary nephrons, with the loop of Henle of each model nephron extending to differing depths of the inner medulla. We used the model to assess how changes in TNa may alter QO2 in different nephron segments and how shifting the TNa sites alters overall kidney QO2. Under baseline conditions, the model predicted a whole kidney TNa/QO2, which denotes the number of moles of Na+ reabsorbed per moles of O2 consumed, of ∼15, with TNa efficiency predicted to be significantly greater in cortical nephron segments than in medullary segments. The TNa/QO2 ratio was generally similar among the superficial and juxtamedullary nephron segments, except for the proximal tubule, where TNa/QO2 was ∼20% higher in superficial nephrons, due to the larger luminal flow along the juxtamedullary proximal tubules and the resulting higher, flow-induced transcellular transport. Moreover, the model predicted that an increase in single-nephron glomerular filtration rate does not significantly affect TNa/QO2 in the proximal tubules but generally increases TNa/QO2 along downstream segments. The latter result can be attributed to the generally higher luminal [Na+], which raises paracellular TNa. Consequently, vulnerable medullary segments, such as the S3 segment and medullary thick ascending limb, may be relatively protected from flow-induced increases in QO2 under pathophysiological conditions. PMID:27707705

  14. Anisotropic surface hole-transport property of triphenylamine-derivative single crystal prepared by solution method

    Energy Technology Data Exchange (ETDEWEB)

    Umeda, Minoru, E-mail: mumeda@vos.nagaokaut.ac.jp [Nagaoka University of Technology, Kamitomioka, Nagaoka, Niigata 940-2188 (Japan); Katagiri, Mitsuhiko; Shironita, Sayoko [Nagaoka University of Technology, Kamitomioka, Nagaoka, Niigata 940-2188 (Japan); Nagayama, Norio [Nagaoka University of Technology, Kamitomioka, Nagaoka, Niigata 940-2188 (Japan); Ricoh Company, Ltd., Nishisawada, Numazu, Shizuoka 410-0007 (Japan)

    2016-12-01

    Highlights: • A hole transport molecule was investigated based on its electrochemical redox characteristics. • The solubility and supersolubility curves of the molecule were measured in order to prepare a large crystal. • The polarization micrograph and XRD results revealed that a single crystal was obtained. • An anisotropic surface conduction, in which the long-axis direction exceeds that of the amorphous layer, was observed. • The anisotropic surface conduction was well explained by the molecular stacked structure. - Abstract: This paper reports the anisotropic hole transport at the triphenylamine-derivative single crystal surface prepared by a solution method. Triphenylamine derivatives are commonly used in a hole-transport material for organic photoconductors of laser-beam printers, in which the materials are used as an amorphous form. For developing organic photovoltaics using the photoconductor’s technology, preparation of a single crystal seems to be a specific way by realizing the high mobility of an organic semiconductor. In this study, a single crystal of 4-(2,2-diphenylethenyl)-N,N-bis(4-methylphenyl)-benzenamine (TPA) was prepared and its anisotropic hole-transport property measured. First, the hole-transport property of the TPA was investigated based on its chemical structure and electrochemical redox characteristics. Next, a large-scale single crystal formation at a high rate was developed by employing a solution method based on its solubility and supersolubility curves. The grown TPA was found to be a single crystal based on the polarization micrograph observation and crystallographic analysis. For the TPA single crystal, an anisotropic surface conduction was found, which was well explained by its molecular stack structure. The measured current in the long-axis direction is one order of magnitude greater than that of amorphous TPA.

  15. All-solution processed composite hole transport layer for quantum dot light emitting diode

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaoli [Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, School of Science, Tianjin University, Tianjin 300072 (China); Synergetic Innovation Center of Chemical Science and Engineering, Tianjin (China); Dai, Haitao, E-mail: htdai@tju.edu.cn [Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, School of Science, Tianjin University, Tianjin 300072 (China); Zhao, Junliang; Wang, Shuguo [Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, School of Science, Tianjin University, Tianjin 300072 (China); Sun, Xiaowei [Department of Electrical & Electronic Engineering, South University of Science and Technology of China, Tangchang Road 1088, Shenzhen, Guangdong 518055 (China)

    2016-03-31

    In the present work, poly-TPD and TCTA composite hole transport layer (HTL) was employed in solution processed CdSe/ZnS quantum dot light emitting diodes (QLEDs). As the doping level of TCTA can determine the carriers transport efficiency of HTL, the proper mixing ratio of TCTA and poly-TPD should be found to optimize the performance of composite HTL for QLEDs. The doping of poly-TPD by low TCTA content can make its HOMO level lower and then reduce the energy barrier height from HTL to quantum dots (QDs), whereas the doping of poly-TPD by the concentrated TCTA results in the degraded performance of QLEDs due to its decreased hole transport mobility. By using the optimized composition with poly-TPD:TCTA (3:1) as the hole transport layer, the luminescence of the device exhibits about double enhancement compared with that of poly-TPD based device. The improvement of luminescence is mainly attributed to the lower energy barrier of hole injection. The Förster resonant energy transfer (FRET) mechanism in the devices was investigated through theoretical and experimental analysis and the results indicate that the TCTA doping makes no difference on FRET. Therefore, the charge injection mechanism dominates the improved performance of the devices. - Highlights: • Quantum dot light emitting diodes (QLEDs) were fabricated by all solution method. • The performance of QLEDs was optimized by varying the composite hole transport layer. • The blend HTL could promote hole injection by optimizing HOMO levels. • The energy transfer mechanism was analyzed by studying Förster resonant energy transfer process.

  16. FOREIGN EXPERIENCE OF MANAGEMENT AND NORMATIVELY-LEGAL ADJUSTING BY INTERNATIONAL TRANSPORTATIONS

    Directory of Open Access Journals (Sweden)

    Nataliya Grigorievna Kuftinova

    2015-09-01

    Full Text Available In this article foreign experience of management is examined by international transportations and prospects of development of management information by bus transportations and transportations of loads. Normatively-legal adjusting, basic norms of domestic law as article of intergovernmental agreements on international transportations.

  17. A cell transportation solution that preserves live circulating tumor cells in patient blood samples.

    Science.gov (United States)

    Stefansson, Steingrimur; Adams, Daniel L; Ershler, William B; Le, Huyen; Ho, David H

    2016-05-06

    Circulating tumor cells (CTCs) are typically collected into CellSave fixative tubes, which kills the cells, but preserves their morphology. Currently, the clinical utility of CTCs is mostly limited to their enumeration. More detailed investigation of CTC biology can be performed on live cells, but obtaining live CTCs is technically challenging, requiring blood collection into biocompatible solutions and rapid isolation which limits transportation options. To overcome the instability of CTCs, we formulated a sugar based cell transportation solution (SBTS) that stabilizes cell viability at ambient temperature. In this study we examined the long term viability of human cancer cell lines, primary cells and CTCs in human blood samples in the SBTS for transportation purposes. Four cell lines, 5 primary human cells and purified human PBMCs were tested to determine the viability of cells stored in the transportation solution at ambient temperature for up to 7 days. We then demonstrated viability of MCF-7 cells spiked into normal blood with SBTS and stored for up to 7 days. A pilot study was then run on blood samples from 3 patients with metastatic malignancies stored with or without SBTS for 6 days. CTCs were then purified by Ficoll separation/microfilter isolation and identified using CTC markers. Cell viability was assessed using trypan blue or CellTracker™ live cell stain. Our results suggest that primary/immortalized cell lines stored in SBTS remain ~90% viable for > 72 h. Further, MCF-7 cells spiked into whole blood remain viable when stored with SBTS for up to 7 days. Finally, live CTCs were isolated from cancer patient blood samples kept in SBTS at ambient temperature for 6 days. No CTCs were isolated from blood samples stored without SBTS. In this proof of principle pilot study we show that viability of cell lines is preserved for days using SBTS. Further, this solution can be used to store patient derived blood samples for eventual isolation of viable CTCs after

  18. A cell transportation solution that preserves live circulating tumor cells in patient blood samples

    International Nuclear Information System (INIS)

    Stefansson, Steingrimur; Adams, Daniel L.; Ershler, William B.; Le, Huyen; Ho, David H.

    2016-01-01

    Circulating tumor cells (CTCs) are typically collected into CellSave fixative tubes, which kills the cells, but preserves their morphology. Currently, the clinical utility of CTCs is mostly limited to their enumeration. More detailed investigation of CTC biology can be performed on live cells, but obtaining live CTCs is technically challenging, requiring blood collection into biocompatible solutions and rapid isolation which limits transportation options. To overcome the instability of CTCs, we formulated a sugar based cell transportation solution (SBTS) that stabilizes cell viability at ambient temperature. In this study we examined the long term viability of human cancer cell lines, primary cells and CTCs in human blood samples in the SBTS for transportation purposes. Four cell lines, 5 primary human cells and purified human PBMCs were tested to determine the viability of cells stored in the transportation solution at ambient temperature for up to 7 days. We then demonstrated viability of MCF-7 cells spiked into normal blood with SBTS and stored for up to 7 days. A pilot study was then run on blood samples from 3 patients with metastatic malignancies stored with or without SBTS for 6 days. CTCs were then purified by Ficoll separation/microfilter isolation and identified using CTC markers. Cell viability was assessed using trypan blue or CellTracker™ live cell stain. Our results suggest that primary/immortalized cell lines stored in SBTS remain ~90 % viable for > 72 h. Further, MCF-7 cells spiked into whole blood remain viable when stored with SBTS for up to 7 days. Finally, live CTCs were isolated from cancer patient blood samples kept in SBTS at ambient temperature for 6 days. No CTCs were isolated from blood samples stored without SBTS. In this proof of principle pilot study we show that viability of cell lines is preserved for days using SBTS. Further, this solution can be used to store patient derived blood samples for eventual isolation of viable CTCs

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

    KAUST Repository

    Li, Ruipeng

    2012-09-04

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

  20. Simulation of unsaturated flow and solute transport at the Las Cruces trench site using the PORFLO-3 computer code

    International Nuclear Information System (INIS)

    Rockhold, M.L.; Wurstner, S.K.

    1991-03-01

    The objective of this work was to test the ability of the PORFLO-3 computer code to simulate water infiltration and solute transport in dry soils. Data from a field-scale unsaturated zone flow and transport experiment, conducted near Las Cruces, New Mexico, were used for model validation. A spatial moment analysis was used to provide a quantitative basis for comparing the mean simulated and observed flow behavior. The scope of this work was limited to two-dimensional simulations of the second experiment at the Las Cruces trench site. Three simulation cases are presented. The first case represents a uniform soil profile, with homogeneous, isotropic hydraulic and transport properties. The second and third cases represent single stochastic realizations of randomly heterogeneous hydraulic conductivity fields, generated from the cumulative probability distribution of the measured data. Two-dimensional simulations produced water content changes that matched the observed data reasonably well. Models that explicitly incorporated heterogeneous hydraulic conductivity fields reproduced the characteristics of the observed data somewhat better than a uniform, homogeneous model. Improved predictions of water content changes at specific spatial locations were obtained by adjusting the soil hydraulic properties. The results of this study should only be considered a qualitative validation of the PORFLO-3 code. However, the results of this study demonstrate the importance of site-specific data for model calibration. Applications of the code for waste management and remediation activities will require site-specific data for model calibration before defensible predictions of unsaturated flow and containment transport can be made. 23 refs., 16 figs., 3 tabs

  1. Effects of Pisha sandstone content on solute transport in a sandy soil.

    Science.gov (United States)

    Zhen, Qing; Zheng, Jiyong; He, Honghua; Han, Fengpeng; Zhang, Xingchang

    2016-02-01

    In sandy soil, water, nutrients and even pollutants are easily leaching to deeper layers. The objective of this study was to assess the effects of Pisha sandstone on soil solute transport in a sandy soil. The miscible displacement technique was used to obtain breakthrough curves (BTCs) of Br(-) as an inert non-adsorbed tracer and Na(+) as an adsorbed tracer. The incorporation of Pisha sandstone into sandy soil was able to prevent the early breakthrough of both tracers by decreasing the saturated hydraulic conductivity compared to the controlled sandy soil column, and the impeding effects increased with Pisha sandstone content. The BTCs of Br(-) were accurately described by both the convection-dispersion equation (CDE) and the two-region model (T-R), and the T-R model fitted the experimental data slightly better than the CDE. The two-site nonequilibrium model (T-S) accurately fit the Na(+) transport data. Pisha sandstone impeded the breakthrough of Na(+) not only by decreasing the saturated hydraulic conductivity but also by increasing the adsorption capacity of the soil. The measured CEC values of Pisha sandstone were up to 11 times larger than those of the sandy soil. The retardation factors (R) determined by the T-S model increased with increasing Pisha sandstone content, and the partition coefficient (K(d)) showed a similar trend to R. According to the results of this study, Pisha sandstone can successfully impede solute transport in a sandy soil column. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. External intermittency prediction using AMR solutions of RANS turbulence and transported PDF models

    Science.gov (United States)

    Olivieri, D. A.; Fairweather, M.; Falle, S. A. E. G.

    2011-12-01

    External intermittency in turbulent round jets is predicted using a Reynolds-averaged Navier-Stokes modelling approach coupled to solutions of the transported probability density function (pdf) equation for scalar variables. Solutions to the descriptive equations are obtained using a finite-volume method, combined with an adaptive mesh refinement algorithm, applied in both physical and compositional space. This method contrasts with conventional approaches to solving the transported pdf equation which generally employ Monte Carlo techniques. Intermittency-modified eddy viscosity and second-moment turbulence closures are used to accommodate the effects of intermittency on the flow field, with the influence of intermittency also included, through modifications to the mixing model, in the transported pdf equation. Predictions of the overall model are compared with experimental data on the velocity and scalar fields in a round jet, as well as against measurements of intermittency profiles and scalar pdfs in a number of flows, with good agreement obtained. For the cases considered, predictions based on the second-moment turbulence closure are clearly superior, although both turbulence models give realistic predictions of the bimodal scalar pdfs observed experimentally.

  3. Nonpoint source solute transport normal to aquifer bedding in heterogeneous, Markov chain random fields

    Science.gov (United States)

    Zhang, Hua; Harter, Thomas; Sivakumar, Bellie

    2006-06-01

    Facies-based geostatistical models have become important tools for analyzing flow and mass transport processes in heterogeneous aquifers. Yet little is known about the relationship between these latter processes and the parameters of facies-based geostatistical models. In this study, we examine the transport of a nonpoint source solute normal (perpendicular) to the major bedding plane of an alluvial aquifer medium that contains multiple geologic facies, including interconnected, high-conductivity (coarse textured) facies. We also evaluate the dependence of the transport behavior on the parameters of the constitutive facies model. A facies-based Markov chain geostatistical model is used to quantify the spatial variability of the aquifer system's hydrostratigraphy. It is integrated with a groundwater flow model and a random walk particle transport model to estimate the solute traveltime probability density function (pdf) for solute flux from the water table to the bottom boundary (the production horizon) of the aquifer. The cases examined include two-, three-, and four-facies models, with mean length anisotropy ratios for horizontal to vertical facies, ek, from 25:1 to 300:1 and with a wide range of facies volume proportions (e.g., from 5 to 95% coarse-textured facies). Predictions of traveltime pdfs are found to be significantly affected by the number of hydrostratigraphic facies identified in the aquifer. Those predictions of traveltime pdfs also are affected by the proportions of coarse-textured sediments, the mean length of the facies (particularly the ratio of length to thickness of coarse materials), and, to a lesser degree, the juxtapositional preference among the hydrostratigraphic facies. In transport normal to the sedimentary bedding plane, traveltime is not lognormally distributed as is often assumed. Also, macrodispersive behavior (variance of the traveltime) is found not to be a unique function of the conductivity variance. For the parameter range

  4. Solute transport in coupled inland-coastal water systems. General conceptualisation and application to Forsmark

    International Nuclear Information System (INIS)

    Jarsjoe, Jerker; Destouni, Georgia; Persson, Klas; Prieto, Carmen

    2007-12-01

    We formulate a general theoretical conceptualisation of solute transport from inland sources to downstream recipients, considering main recipient load contributions from all different nutrient and pollutant sources that may exist within any catchment. Since the conceptualisation is model independent, its main hydrological factors and mass delivery factors can be quantified on the basis of inputs to and outputs from any considered analytical or numerical model. Some of the conceptually considered source contribution and transport pathway combinations are however commonly neglected in catchment-scale solute transport and attenuation modelling, in particular those related to subsurface sources, diffuse sources at the land surface and direct groundwater transport into the recipient. The conceptual framework provides a possible tool for clarification of underlying and often implicit model assumptions, which can be useful for e.g. inter-model comparisons. In order to further clarify and explain research questions that may be of particular importance for transport pathways from deep groundwater surrounding a repository, we concretise and interpret some selected transport scenarios for model conditions in the Forsmark area. Possible uncertainties in coastal discharge predictions, related to uncertain spatial variation of evapotranspiration within the catchment, were shown to be small for the relatively large, focused surface water discharges from land to sea, because local differences were averaged out along the length of the main water flow paths. In contrast, local flux values within the diffuse groundwater flow field from land to sea are more uncertain, although estimates of mean values and total sums of submarine groundwater discharge (SGD) along some considerable coastline length may be robust. The present results show that 80% to 90% of the total coastal discharge of Forsmark occurred through focused flows in visible streams, whereas the remaining 10% to 20% was

  5. Improved performance of organic solar cells with solution processed hole transport layer

    Science.gov (United States)

    Bhargav, Ranoo; Gairola, S. P.; Patra, Asit; Naqvi, Samya; Dhawan, S. K.

    2018-06-01

    This work is based on Cobalt Oxide as solution processed, inexpensive and effective hole transport layer (HTL) for efficient organic photovoltaic applications (OPVs). In Organic solar cell (OSC) devices ITO coated glass substrate used as a transparent anode electrode for light incident, HTL material Co3O4 dissolve in DMF solvent deposited on anode electrode, after that active layer material (donor/acceptor) deposited on to HTL and finally Al were deposited by thermal evaporation used as cathode electrode. These devices were fabricated with PCDTBT well known low band gap donor material in OSCs and blended with PC71BM as an acceptor material using simplest device structure ITO/Co3O4/active layer/Al at ambient conditions. The power conversion efficiencies (PCEs) based on Co3O4 and PEDOT:PSS have been achieved to up to 3.21% and 1.47% with PCDTBT respectively. In this study we reported that the devices fabricated with Co3O4 showed better performance as compare to the devices fabricated with well known and most studied solution processed HTL material PEDOT:PSS under identical environmental conditions. The surface morphology of the HTL film was characterized by (AFM). Lastly, we have provided Co3O4 as an efficient hole transport material HTL for solution processed organic photovoltaic applications.

  6. Assessment of assembly homogenized two-steps core dynamic calculations using direct whole core transport solutions

    International Nuclear Information System (INIS)

    Hursin, Mathieu; Downar, Thomas J.; Yoon, Joo Il; Joo, Han Gyu

    2016-01-01

    Highlights: • Reactivity initiated accident analysis with direct whole core transient transport code. • Comparison with usual “two steps” procedure. • Effect of effective delayed neutron fraction definition on energy deposition in the fuel. • Effect of homogenized few-group cross sections generation at the assembly level on energy deposition in the fuel. • Effect of effective fuel temperature definition on energy deposition in the fuel. - Abstract: The impact of the approximations in the “two-steps” procedure used in the current generation of nodal simulators for core transient calculations is assessed by using a higher order solution obtained from a direct, whole core, transient transport calculation. A control rod ejection accident in an idealized minicore is analyzed with PARCS, which uses the two-steps procedure and DeCART which provides the higher order solution. DeCART is used as lattice code to provide the homogenized cross sections and kinetics parameters to PARCS. The approximations made by using (1) the homogenized few-group cross sections and kinetic parameters generated at the assembly level, (2) an effective delayed neutrons fraction, (3) an effective fuel temperature and (4) the few-group formulation are investigated in terms of global and local core power behavior. The results presented in the paper show that the current two-steps procedure produces sufficiently accurate transient results with respect to the direct whole core calculation solution, provided that its parameters are carefully generated using the prescriptions described in the present article.

  7. Calculated k-effectives for light water reactor typical, U + Pu nitrate solution critical experiments

    International Nuclear Information System (INIS)

    Primm, R.T. III; Mincey, J.F.

    1982-01-01

    The Department of Energy's Consolidated Fuel Reprocessing Program has as a goal the design of nuclear fuel reprocessing equipment. In order to validate computer codes used for criticality analyses in the design of such equipment, k-effectives have been calculated for several U + Pu nitrate solution critical experiments. As of January 1981, descriptions of 45 unpoisoned, U + Pu solution experiments were available in the open literature. Twelve of these experiments were performed with solutions which have physical characteristics typical of dissolved, light water reactor fuel. This paper contains a discussion of these twelve experiments, a review of the calculational procedure used to determine k-effectives, and the results of the calculations

  8. Enterprise security IT security solutions : concepts, practical experiences, technologies

    CERN Document Server

    Fumy, Walter

    2013-01-01

    Addressing IT managers and staff, as well as CIOs and other executives dealing with corporate IT security, this book provides a broad knowledge on the major security issues affecting today's corporations and organizations, and presents state-of-the-art concepts and current trends for securing an enterprise.Areas covered include information security management, network and system security, identity and access management (IAM), authentication (including smart card based solutions and biometrics), and security certification. In-depth discussion of relevant technologies and standards (including cr

  9. FASTREACT – An efficient numerical framework for the solution of reactive transport problems

    International Nuclear Information System (INIS)

    Trinchero, Paolo; Molinero, Jorge; Román-Ross, Gabriela; Berglund, Sten; Selroos, Jan-Olof

    2014-01-01

    Highlights: • We present a tool for the efficient solution of reactive transport problems. • The tool is used to simulate radionuclide transport in a two-dimensional medium. • The results are successfully compared with those obtained using an Eulerian approach. • A large-scale application example is also solved. • The results show that the proposed tool can efficiently solve large-scale models. - Abstract: In the framework of safety assessment studies for geological disposal, large scale reactive transport models are powerful inter-disciplinary tools aiming at supporting regulatory decision making as well as providing input to repository engineering activities. Important aspects of these kinds of models are their often very large temporal and spatial modelling scales and the need to integrate different non-linear processes (e.g., mineral dissolution and precipitation, adsorption and desorption, microbial reactions and redox transformations). It turns out that these types of models may be computationally highly demanding. In this work, we present a Lagrangian-based framework, denoted as FASTREACT, that aims at solving multi-component-reactive transport problems with a computationally efficient approach allowing complex modelling problems to be solved in large spatial and temporal scales. The tool has been applied to simulate radionuclide migration in a synthetic heterogeneous transmissivity field and the results have been successfully compared with those obtained using a standard Eulerian approach. Finally, the same geochemical model has been coupled to an ensemble of realistic three-dimensional transport pathways to simulate the migration of a set of radionuclides from a hypothetical repository for spent nuclear fuel to the surface. The results of this modelling exercise, which includes key processes such as the exchange of mass between the conductive fractures and the matrix, show that FASTREACT can efficiently solve large-scale reactive transport models

  10. Urban Ecology Solutions - Status of Knowledge and Experience

    DEFF Research Database (Denmark)

    Elle, Morten; Jensen, Jesper Ole

    The book describes the history of urban ecology in Denmark, criterias for 'good' urban ecology and a vast number of methods and technologies that have the potential of making the built environment more sustainable - based on the present knowledge and experience....

  11. Application of preconditioned GMRES to the numerical solution of the neutron transport equation

    International Nuclear Information System (INIS)

    Patton, B.W.; Holloway, J.P.

    2002-01-01

    The generalized minimal residual (GMRES) method with right preconditioning is examined as an alternative to both standard and accelerated transport sweeps for the iterative solution of the diamond differenced discrete ordinates neutron transport equation. Incomplete factorization (ILU) type preconditioners are used to determine their effectiveness in accelerating GMRES for this application. ILU(τ), which requires the specification of a dropping criteria τ, proves to be a good choice for the types of problems examined in this paper. The combination of ILU(τ) and GMRES is compared with both DSA and unaccelerated transport sweeps for several model problems. It is found that the computational workload of the ILU(τ)-GMRES combination scales nonlinearly with the number of energy groups and quadrature order, making this technique most effective for problems with a small number of groups and discrete ordinates. However, the cost of preconditioner construction can be amortized over several calculations with different source and/or boundary values. Preconditioners built upon standard transport sweep algorithms are also evaluated as to their effectiveness in accelerating the convergence of GMRES. These preconditioners show better scaling with such problem parameters as the scattering ratio, the number of discrete ordinates, and the number of spatial meshes. These sweeps based preconditioners can also be cast in a matrix free form that greatly reduces storage requirements

  12. PARTRACK - A particle tracking algorithm for transport and dispersion of solutes in a sparsely fractured rock

    International Nuclear Information System (INIS)

    Svensson, Urban

    2001-04-01

    A particle tracking algorithm, PARTRACK, that simulates transport and dispersion in a sparsely fractured rock is described. The main novel feature of the algorithm is the introduction of multiple particle states. It is demonstrated that the introduction of this feature allows for the simultaneous simulation of Taylor dispersion, sorption and matrix diffusion. A number of test cases are used to verify and demonstrate the features of PARTRACK. It is shown that PARTRACK can simulate the following processes, believed to be important for the problem addressed: the split up of a tracer cloud at a fracture intersection, channeling in a fracture plane, Taylor dispersion and matrix diffusion and sorption. From the results of the test cases, it is concluded that PARTRACK is an adequate framework for simulation of transport and dispersion of a solute in a sparsely fractured rock

  13. Modeling of amorphous pocket formation in silicon by numerical solution of the heat transport equation

    International Nuclear Information System (INIS)

    Kovac, D.; Otto, G.; Hobler, G.

    2005-01-01

    In this paper we present a model of amorphous pocket formation that is based on binary collision simulations to generate the distribution of deposited energy, and on numerical solution of the heat transport equation to describe the quenching process. The heat transport equation is modified to consider the heat of melting when the melting temperature is crossed at any point in space. It is discretized with finite differences on grid points that coincide with the crystallographic lattice sites, which allows easy determination of molten atoms. Atoms are considered molten if the average of their energy and the energy of their neighbors meets the melting criterion. The results obtained with this model are in good overall agreement with published experimental data on P, As, Te and Tl implantations in Si and with data on the polyatomic effect at cryogenic temperature

  14. Transport and dosimetric solutions for the ELIMED laser-driven beam line

    Energy Technology Data Exchange (ETDEWEB)

    Cirrone, G.A.P. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Romano, F. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Medical Physics School, University of Catania, Via S. Sofia 64 - 95125 Catania (Italy); Scuderi, V. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Institute of Physics ASCR, v.v.i. (FZU), ELI-Beamlines Project, Na Slovance 2, 182 21 Prague (Czech Republic); Amato, A. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Candiano, G. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Medical Physics School, University of Catania, Via S. Sofia 64 - 95125 Catania (Italy); Cuttone, G. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Giove, D. [INFN Sezione di Milano, Via Celoria 16, Milano (Italy); Korn, G.; Krasa, J. [Institute of Physics ASCR, v.v.i. (FZU), ELI-Beamlines Project, Na Slovance 2, 182 21 Prague (Czech Republic); Leanza, R. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Universitá degli Studi di Catania, Dipartimento di Fisica e Astronomia, Via S. Sofia 64, Catania (Italy); Manna, R. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Maggiore, M. [INFN-LNL, Viale dell' Universitá 2 - 35020 Legnaro (PD) (Italy); Marchese, V. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Margarone, D. [Institute of Physics ASCR, v.v.i. (FZU), ELI-Beamlines Project, Na Slovance 2, 182 21 Prague (Czech Republic); Milluzzo, G. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Universitá degli Studi di Catania, Dipartimento di Fisica e Astronomia, Via S. Sofia 64, Catania (Italy); Petringa, G. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Sabini, M.G. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Azienda Ospedaliera Cannizzaro, Via Messina 829 - 95100 Catania (Italy); Schillaci, F. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Medical Physics School, University of Catania, Via S. Sofia 64 - 95125 Catania (Italy); and others

    2015-10-01

    Within 2017, the ELIMED (ELI-Beamlines MEDical applications) transport beam-line and dosimetric systems for laser-generated beams will be installed at the ELI-Beamlines facility in Prague (CZ), inside the ELIMAIA (ELI Multidisciplinary Applications of laser–Ion Acceleration) interaction room. The beam-line will be composed of two sections: one in vacuum, devoted to the collecting, focusing and energy selection of the primary beam and the second in air, where the ELIMED beam-line dosimetric devices will be located. This paper briefly describes the transport solutions that will be adopted together with the main dosimetric approaches. In particular, the description of an innovative Faraday Cup detector with its preliminary experimental tests will be reported.

  15. Method of model reduction and multifidelity models for solute transport in random layered porous media

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zhijie; Tartakovsky, Alexandre M.

    2017-09-01

    This work presents a hierarchical model for solute transport in 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 hierarchical 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. We observe that velocity fluctuations enhance dispersion in a non-monotonic fashion: the dispersion initially increases with correlation length λ, reaches a maximum, and decreases to zero at infinity. Maximum enhancement can be obtained at the correlation length about 0.25 the size of the porous media perpendicular to flow.

  16. Conventional transport fuels quality and ATF : recent Asian experience

    Energy Technology Data Exchange (ETDEWEB)

    Desbiens, R. [Consultec, Montreal, PQ (Canada)

    2002-07-01

    The experience gained in Manila, Philippines, with regard to transport fuels, was discussed during this presentation. It is estimated that 70 to 80 per cent of air pollution in the city of Manila is generated by vehicular traffic. Diesel-fueled vehicles operate all hours of the day, and motorized tricycles powered by a two-stroke engine, are cause for concern for local authorities. Several factors play a role in the problems experienced: vehicle ownership, poor air, congestion and noise in urban areas, poor transport infrastructure, coupled with policy problems such as fuel and vehicle quality standards, poor monitoring, ancient technologies, etc. The motorization of cities was examined, and special emphasis was places on the situation in Asia. The situation in China was looked at, where approximately 15 million automobiles are in use, with an annual increase of 11 to 13 per cent. The air pollution caused by motor vehicles in China was discussed, and new vehicle emission standards for China were presented. The issue of fuel injection systems for motorcycles in China was discussed, and the author mentioned that cost and reliability problems require further improvement. The use of compressed natural gas vehicles in Beijing was looked at, and some of the barriers are lack of public awareness, capital shortages, high price of natural gas, and shortage of advanced technologies. A feasibility study for the introduction of compressed natural gas vehicles in Beijing was conducted and the main findings presented. Public transport management in Hong Kong was reviewed, including the use of alternative environmentally friendly vehicles and fuel. A look at India, and specifically Delhi, was presented. The norms concerning vehicle emissions in India were briefly reviewed, followed by fuel quality improvements, and compressed natural gas vehicles. The author then discussed alternative fuels in Korea and the country's compressed natural gas bus promotion policy. The next

  17. Ion Transport in Confined Geometries below the Nanoscale: Access Resistance Dominates Protein Channel Conductance in Diluted Solutions.

    Science.gov (United States)

    Alcaraz, Antonio; López, M Lidón; Queralt-Martín, María; Aguilella, Vicente M

    2017-10-24

    Synthetic nanopores and mesoscopic protein channels have common traits like the importance of electrostatic interactions between the permeating ions and the nanochannel. Ion transport at the nanoscale occurs under confinement conditions so that the usual assumptions made in microfluidics are challenged, among others, by interfacial effects such as access resistance (AR). Here, we show that a sound interpretation of electrophysiological measurements in terms of channel ion selective properties requires the consideration of interfacial effects, up to the point that they dominate protein channel conductance in diluted solutions. We measure AR in a large ion channel, the bacterial porin OmpF, by means of single-channel conductance measurements in electrolyte solutions containing varying concentrations of high molecular weight PEG, sterically excluded from the pore. Comparison of experiments performed in charged and neutral planar membranes shows that lipid surface charges modify the ion distribution and determine the value of AR, indicating that lipid molecules are more than passive scaffolds even in the case of large transmembrane proteins. We also found that AR may reach up to 80% of the total channel conductance in diluted solutions, where electrophysiological recordings register essentially the AR of the system and depend marginally on the pore characteristics. These findings may have implications for several low aspect ratio biological channels that perform their physiological function in a low ionic strength and macromolecule crowded environment, just the two conditions enhancing the AR contribution.

  18. An Experimental and Finite Element Protocol to Investigate the Transport of Neutral and Charged Solutes across Articular Cartilage.

    Science.gov (United States)

    Arbabi, Vahid; Pouran, Behdad; Zadpoor, Amir A; Weinans, Harrie

    2017-04-23

    Osteoarthritis (OA) is a debilitating disease that is associated with degeneration of articular cartilage and subchondral bone. Degeneration of articular cartilage impairs its load-bearing function substantially as it experiences tremendous chemical degradation, i.e. proteoglycan loss and collagen fibril disruption. One promising way to investigate chemical damage mechanisms during OA is to expose the cartilage specimens to an external solute and monitor the diffusion of the molecules. The degree of cartilage damage (i.e. concentration and configuration of essential macromolecules) is associated with collisional energy loss of external solutes while moving across articular cartilage creates different diffusion characteristics compared to healthy cartilage. In this study, we introduce a protocol, which consists of several steps and is based on previously developed experimental micro-Computed Tomography (micro-CT) and finite element modeling. The transport of charged and uncharged iodinated molecules is first recorded using micro-CT, which is followed by applying biphasic-solute and multiphasic finite element models to obtain diffusion coefficients and fixed charge densities across cartilage zones.

  19. Solution-grown organic single-crystalline p-n junctions with ambipolar charge transport.

    Science.gov (United States)

    Fan, Congcheng; Zoombelt, Arjan P; Jiang, Hao; Fu, Weifei; Wu, Jiake; Yuan, Wentao; Wang, Yong; Li, Hanying; Chen, Hongzheng; Bao, Zhenan

    2013-10-25

    Organic single-crystalline p-n junctions are grown from mixed solutions. First, C60 crystals (n-type) form and, subsequently, C8-BTBT crystals (p-type) nucleate heterogeneously on the C60 crystals. Both crystals continue to grow simultaneously into single-crystalline p-n junctions that exhibit ambipolar charge transport characteristics. This work provides a platform to study organic single-crystalline p-n junctions. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Global existence of weak solutions to dissipative transport equations with nonlocal velocity

    Science.gov (United States)

    Bae, Hantaek; Granero-Belinchón, Rafael; Lazar, Omar

    2018-04-01

    We consider 1D dissipative transport equations with nonlocal velocity field: where is a nonlocal operator given by a Fourier multiplier. We especially consider two types of nonlocal operators: (1) , the Hilbert transform, (2) . In this paper, we show several global existence of weak solutions depending on the range of γ, δ and α. When , we take initial data having finite energy, while we take initial data in weighted function spaces (in the real variables or in the Fourier variables), which have infinite energy, when .

  1. Solution methods for compartment models of transport through the environment using numerical inversion of Laplace transforms

    International Nuclear Information System (INIS)

    Garratt, T.J.

    1989-05-01

    Compartment models for the transport of radionuclides in the biosphere are conventionally solved using a numerical time-stepping procedure. This report examines an alternative method based on the numerical inversion of Laplace transforms, which is potentially more efficient and accurate for some classes of problem. The central problem considered is the most efficient and robust technique for solving the Laplace-transformed rate equations. The conclusion is that Gaussian elimination is the most efficient and robust solution method. A general compartment model has been implemented on a personal computer and used to solve a realistic case including radionuclide decay chains. (author)

  2. WAP Based An Alternative Solution for Traffic Transportation Problem in Sidoarjo Surrounding Area Using AHP

    Directory of Open Access Journals (Sweden)

    Arna Fariza

    2009-08-01

    Full Text Available In line with the increasing interest on Lapindo mud disaster which causes several roadway covered by mud, there is a need to give an alternative solution for traffic transportation problem in surrounding area. The possible criteria for the solution of this road way are length, surface, traffic, and width of the road. Types of vehicle across the road also give a contribution to the criteria. By using Geography Information System (GIS, it is easy to all drivers to take decision which way has to be chosen based on the real condition. GIS is used to visualize the alternative road, which is possible to take. Analytic Hierarchy Processing (AHP is a decision method which is based on many criteria and alternatives. The input of AHP can be a preference or real value. Applied AHP to decide value of each alternative is based on application of Wireless Application Protocol (WAP assessment.

  3. Water and solute transport in agricultural soils predicted by volumetric clay and silt contents

    DEFF Research Database (Denmark)

    Karup, Dan; Møldrup, Per; Paradelo Pérez, Marcos

    2016-01-01

    tracer mass could be well fitted to an analytical solution to the classical convection-dispersion equation. Both cumulative tracer mass and concentration as a function of time were hereby reasonable well predicted from the simple inputs of bulk density, clay and silt contents, and applied tracer mass......Solute transport through the soil matrix is heterogeneous and greatly affected by soil texture, soil structure, and macropore networks. This study examined the relationship between tracer breakthrough characteristics, soil hydraulic properties, and basic soil properties. Hundred...... of the soil structure rather than the actual formation of macropores causing preferential flow. The arrival times of 5 % and up to 50 % of the tracer mass were found to be strongly correlated with volumetric fines content. The hereby predicted tracer concentration breakthrough points up to 50% of applied...

  4. The solution of the multigroup neutron transport equation using spherical harmonics

    International Nuclear Information System (INIS)

    Fletcher, K.

    1981-01-01

    A solution of the multi-group neutron transport equation in up to three space dimensions is presented. The flux is expanded in a series of unnormalised spherical harmonics. Using the various recurrence formulae a linked set of first order differential equations is obtained for the moments psisup(g)sub(lm)(r), γsup(g)sub(lm)(r). Terms with odd l are eliminated resulting in a second order system which is solved by two methods. The first is a finite difference formulation using an iterative procedure, secondly, in XYZ and XY geometry a finite element solution is given. Results for a test problem using both methods are exhibited and compared. (orig./RW) [de

  5. Matrix-oriented implementation for the numerical solution of the partial differential equations governing flows and transport in porous media

    KAUST Repository

    Sun, Shuyu; Salama, Amgad; El-Amin, Mohamed

    2012-01-01

    In this paper we introduce a new technique for the numerical solution of the various partial differential equations governing flow and transport phenomena in porous media. This method is proposed to be used in high level programming languages like

  6. Feedback from operational experience in front-end transportation

    International Nuclear Information System (INIS)

    Mondonel, J.L.; Parison, C.

    1998-01-01

    Transport forms an integral part of the nuclear fuel cycle, representing the strategic link between each stage of the cycle. In a way there is a transport cycle that parallels the nuclear fuel cycle. This concerns particularly the front-end of the cycle whose steps - mining conversion, enrichment and fuel fabrication - require numerous transports. Back-end shipments involve a handful of countries, but front-end transports involve all five continents, and many exotic countries. All over Europe such transports are routinely performed with an excellent safety track record. Transnucleaire dominates the French nuclear transportation market and carries out both front and back-end transports. For instance in 1996 more than 28,400 front-end packages were transported as well as more than 3,600 back-end packages. However front-end transport is now a business undergoing much change. A nuclear transportation company must now cope with an evolving picture including new technical requirements, new transportation schemes and new business conditions. This paper describes the latest evolutions in terms of front-end transportation and the way this activity is carried out by Transnucleaire, and goes on to discuss future prospects. (authors)

  7. Current Solutions: Recent Experience in Interconnecting Distributed Energy Resources

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, M.

    2003-09-01

    This report catalogues selected real-world technical experiences of utilities and customers that have interconnected distributed energy assets with the electric grid. This study was initiated to assess the actual technical practices for interconnecting distributed generation and had a particular focus on the technical issues covered under the Institute of Electrical and Electronics Engineers (IEEE) 1547(TM) Standard for Interconnecting Distributed Resources With Electric Power Systems.

  8. Location-based solutions in the Experience centre

    DEFF Research Database (Denmark)

    Hansen, Dan Witzner; Alapetite, Alexandre; Holdgaard, Nanna

    In this paper we present a prototype system for location-based guiding. A user survey has been conducted and the observations are used to support design choices. The prototype allows for both indoor and outdoor navigation at and in the vicinity of the experience centre NaturBornholm1 in Denmark u...... using a combination of Bluetooth, GPS and QR-codes. Bluetooth and GPS are used for location-based information and QR-codes are used to convey user preferences....

  9. Location-based solutions in the Experience centre

    DEFF Research Database (Denmark)

    Witzner Hansen, Dan; Alapetite, Alexandre Philippe Bernard; Holdgaard, Nanna

    2008-01-01

    In this paper we present a prototype system for location-based guiding. A user survey has been conducted and the observations are used to support design choices. The prototype allows for both indoor and outdoor navigation at and in the vicinity of the experience centre NaturBornholm1 in Denmark u...... using a combination of Bluetooth, GPS and QRcodes. Bluetooth and GPS are used for location-based information and QR-codes are used to convey user preferences....

  10. Application of radioanalytical methods in the quantification of solute transport in plants

    International Nuclear Information System (INIS)

    Hornik, M.

    2016-01-01

    The present habilitation thesis is elaborated as a compilation of published scientific papers supplemented with a commentary. The primary objective of the work was to bring the results and knowledge applicable to the further development of application possibilities of nuclear analytical chemistry, especially in the field of radioindication methods and application of positron emitters in connection with the positron emission tomography (PET) as well. In the work, these methods and techniques are developed mainly in the context of the solution of environmental issues related to the analysis and remediation of contaminated or degraded environment (water and soil), but also partially in the field of plant production or plant research. In terms of the achieved results and knowledge, the work is divided into three separated sections. The first part is dedicated to the application of radioindication methods, as well as others, non-radioanalytical methods and approaches in the characterization of plant biomass (biomass of terrestrial and aquatic mosses, and waste plant biomass) as alternative sorbents served to the separation and removal of (radio)toxic metals from contaminated or waste waters, as well as in the quantification and description of the sorption processes proceed under conditions of batch or continuous flow systems. The second part describes the results concerning on the quantification and visual description of the processes of (radio)toxic metals and microelements uptake and translocation in plant tissues using radioisotopes (β- and γ-emitters) of these metals and application of the methods of direct gamma spectrometry and autoradiography as well. The main aim of these experiments was to evaluate the possibilities of utilization of selected plant species in phytoremediation of contaminated soils and waters, as well as the possibilities affecting the effectiveness of uptake and translocation of these metals in the plant tissues mainly in dependence on their

  11. Correlation of Aquaporins and Transmembrane Solute Transporters Revealed by Genome-Wide Analysis in Developing Maize Leaf

    Directory of Open Access Journals (Sweden)

    Xun Yue

    2012-01-01

    Full Text Available Aquaporins are multifunctional membrane channels that facilitate the transmembrane transport of water and solutes. When transmembrane mineral nutrient transporters exhibit the same expression patterns as aquaporins under diverse temporal and physiological conditions, there is a greater probability that they interact. In this study, genome-wide temporal profiling of transcripts analysis and coexpression network-based approaches are used to examine the significant specificity correlation of aquaporins and transmembrane solute transporters in developing maize leaf. The results indicate that specific maize aquaporins are related to specific transmembrane solute transporters. The analysis demonstrates a systems-level correlation between aquaporins, nutrient transporters, and the homeostasis of mineral nutrients in developing maize leaf. Our results provide a resource for further studies into the physiological function of these aquaporins.

  12. Transport of neutral solute across articular cartilage: the role of zonal diffusivities.

    Science.gov (United States)

    Arbabi, V; Pouran, B; Weinans, H; Zadpoor, A A

    2015-07-01

    Transport of solutes through diffusion is an important metabolic mechanism for the avascular cartilage tissue. Three types of interconnected physical phenomena, namely mechanical, electrical, and chemical, are all involved in the physics of transport in cartilage. In this study, we use a carefully designed experimental-computational setup to separate the effects of mechanical and chemical factors from those of electrical charges. Axial diffusion of a neutral solute Iodixanol into cartilage was monitored using calibrated microcomputed tomography micro-CT images for up to 48 hr. A biphasic-solute computational model was fitted to the experimental data to determine the diffusion coefficients of cartilage. Cartilage was modeled either using one single diffusion coefficient (single-zone model) or using three diffusion coefficients corresponding to superficial, middle, and deep cartilage zones (multizone model). It was observed that the single-zone model cannot capture the entire concentration-time curve and under-predicts the near-equilibrium concentration values, whereas the multizone model could very well match the experimental data. The diffusion coefficient of the superficial zone was found to be at least one order of magnitude larger than that of the middle zone. Since neutral solutes were used, glycosaminoglycan (GAG) content cannot be the primary reason behind such large differences between the diffusion coefficients of the different cartilage zones. It is therefore concluded that other features of the different cartilage zones such as water content and the organization (orientation) of collagen fibers may be enough to cause large differences in diffusion coefficients through the cartilage thickness.

  13. Transport of fluid and solutes in the body II. Model validation and implications.

    Science.gov (United States)

    Gyenge, C C; Bowen, B D; Reed, R K; Bert, J L

    1999-09-01

    A mathematical model of short-term whole body fluid, protein, and ion distribution and transport developed earlier [see companion paper: C. C. Gyenge, B. D. Bowen, R. K. Reed, and J. L. Bert. Am. J. Physiol. 277 (Heart Circ. Physiol. 46): H1215-H1227, 1999] is validated using experimental data available in the literature. The model was tested against data measured for the following three types of experimental infusions: 1) hyperosmolar saline solutions with an osmolarity in the range of 2,000-2,400 mosmol/l, 2) saline solutions with an osmolarity of approximately 270 mosmol/l and composition comparable with Ringer solution, and 3) an isosmotic NaCl solution with an osmolarity of approximately 300 mosmol/l. Good agreement between the model predictions and the experimental data was obtained with respect to the trends and magnitudes of fluid shifts between the intra- and extracellular compartments, extracellular ion and protein contents, and hematocrit values. The model is also able to yield information about inaccessible or difficult-to-measure system variables such as intracellular ion contents, cellular volumes, and fluid fluxes across the vascular capillary membrane, data that can be used to help interpret the behavior of the system.

  14. Water, solute and heat transport in the soil: the Australian connection

    Science.gov (United States)

    Knight, John

    2016-04-01

    The interest of Peter Raats in water, solute and heat transport in the soil has led to scientific and/or personal interactions with several Australian scientists such as John Philip, David Smiles, Greg Davis and John Knight. Along with John Philip and Robin Wooding, Peter was an early user of the Gardner (1958) linearised model of soil water flow, which brought him into competition with John Philip. I will discuss some of Peter's solutions relevant to infiltration from line and point sources, cavities and basins. A visit to Canberra, Australia in the early 1980s led to joint work on soil water flow, and on combined water and solute movement with David Smiles and others. In 1983 Peter was on the PhD committee for Greg Davis at the University of Wollongong, and some of the methods in his thesis 'Mathematical modelling of rate-limiting mechanisms of pyritic oxidation in overburden dumps' were later used by Peter's student Sjoerd van der Zee. David Smiles and Peter wrote a survey article 'Hydrology of swelling clay soils' in 2005. In the last decade Peter has been investigating the history of groundwater and vadose zone hydrology, and recently he and I have been bringing to light the largely forgotten work of Lewis Fry Richardson on finite difference solution of the heat equation, drainage theory, soil physics, and the soil-plant-atmosphere continuum.

  15. Effect of surface charge of immortalized mouse cerebral endothelial cell monolayer on transport of charged solutes.

    Science.gov (United States)

    Yuan, Wei; Li, Guanglei; Gil, Eun Seok; Lowe, Tao Lu; Fu, Bingmei M

    2010-04-01

    Charge carried by the surface glycocalyx layer (SGL) of the cerebral endothelium has been shown to significantly modulate the permeability of the blood-brain barrier (BBB) to charged solutes in vivo. The cultured monolayer of bEnd3, an immortalized mouse cerebral endothelial cell line, is becoming a popular in vitro BBB model due to its easy growth and maintenance of many BBB characteristics over repeated passages. To test whether the SGL of bEnd3 monolayer carries similar charge as that in the intact BBB and quantify this charge, which can be characterized by the SGL thickness (L(f)) and charge density (C(mf)), we measured the solute permeability of bEnd3 monolayer to neutral solutes and to solutes with similar size but opposite charges: negatively charged alpha-lactalbumin (-11) and positively charged ribonuclease (+3). Combining the measured permeability data with a transport model across the cell monolayer, we predicted the L(f) and the C(mf) of bEnd3 monolayer, which is approximately 160 nm and approximately 25 mEq/L, respectively. We also investigated whether orosomucoid, a plasma glycoprotein modulating the charge of the intact BBB, alters the charge of bEnd3 monolayer. We found that 1 mg/mL orosomucoid would increase SGL charge density of bEnd3 monolayer to approximately 2-fold of its control value.

  16. Solute transport in coupled inland-coastal water systems. General conceptualisation and application to Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Jarsjoe, Jerker; Destouni, Georgia; Persson, Klas; Prieto, Carmen (Dept. of Physical Geography, Quaternary Geology, Stockholm Univ., Stockholm (Sweden))

    2007-12-15

    We formulate a general theoretical conceptualisation of solute transport from inland sources to downstream recipients, considering main recipient load contributions from all different nutrient and pollutant sources that may exist within any catchment. Since the conceptualisation is model independent, its main hydrological factors and mass delivery factors can be quantified on the basis of inputs to and outputs from any considered analytical or numerical model. Some of the conceptually considered source contribution and transport pathway combinations are however commonly neglected in catchment-scale solute transport and attenuation modelling, in particular those related to subsurface sources, diffuse sources at the land surface and direct groundwater transport into the recipient. The conceptual framework provides a possible tool for clarification of underlying and often implicit model assumptions, which can be useful for e.g. inter-model comparisons. In order to further clarify and explain research questions that may be of particular importance for transport pathways from deep groundwater surrounding a repository, we concretise and interpret some selected transport scenarios for model conditions in the Forsmark area. Possible uncertainties in coastal discharge predictions, related to uncertain spatial variation of evapotranspiration within the catchment, were shown to be small for the relatively large, focused surface water discharges from land to sea, because local differences were averaged out along the length of the main water flow paths. In contrast, local flux values within the diffuse groundwater flow field from land to sea are more uncertain, although estimates of mean values and total sums of submarine groundwater discharge (SGD) along some considerable coastline length may be robust. The present results show that 80% to 90% of the total coastal discharge of Forsmark occurred through focused flows in visible streams, whereas the remaining 10% to 20% was

  17. BUILDING CONCEPTUAL AND MATHEMATICAL MODEL FOR WATER FLOW AND SOLUTE TRANSPORT IN THE UNSATURATED ZONE AT KOSNICA SITE

    Directory of Open Access Journals (Sweden)

    Stanko Ružičić

    2012-12-01

    Full Text Available Conceptual model of flow and solute transport in unsaturated zone at Kosnica site, which is the basis for modeling pollution migration through the unsaturated zone to groundwater, is set up. The main characteristics of the unsaturated zone of the Kosnica site are described. Detailed description of investigated profile of unsaturated zone, with all necessary analytical results performed and used in building of conceptual models, is presented. Experiments that are in progress and processes which are modeled are stated. Monitoring of parameters necessary for calibration of models is presented. The ultimate goal of research is risk assessment of groundwater contamination at Kosnica site that has its source in or on unsaturated zone.

  18. Experimental investigation of the impact of compound-specific dispersion and electrostatic interactions on transient transport and solute breakthrough

    Science.gov (United States)

    Muniruzzaman, Muhammad; Rolle, Massimo

    2017-02-01

    This study investigates the effects of compound-specific diffusion/dispersion and electrochemical migration on transient solute transport in saturated porous media. We conducted laboratory bench-scale experiments, under advection-dominated regimes (seepage velocity: 0.5, 5, 25 m/d), in a quasi two-dimensional flow-through setup using pulse injection of multiple tracers (both uncharged and ionic species). Extensive sampling and measurement of solutes' concentrations (˜1500 samples; >3000 measurements) were performed at the outlet of the flow-through setup, at high spatial and temporal resolution. The experimental results show that compound-specific effects and charge-induced Coulombic interactions are important not only at low velocities and/or for steady state plumes but also for transient transport under high flow velocities. Such effects can lead to a remarkably different behavior of measured breakthrough curves also at very high Péclet numbers. To quantitatively interpret the experimental results, we used four modeling approaches: classical advection-dispersion equation (ADE), continuous time random walk (CTRW), dual-domain mass transfer model (DDMT), and a multicomponent ionic dispersion model. The latter is based on the multicomponent formulation of coupled diffusive/dispersive fluxes and was used to describe and explain the electrostatic effects of charged species. Furthermore, we determined experimentally the temporal profiles of the flux-related dilution index. This metric of mixing, used in connection with the traditional solute breakthrough curves, proved to be useful to correctly distinguish between plume spreading and mixing, particularly for the cases in which the sole analysis of integrated concentration breakthrough curves may lead to erroneous interpretation of plume dilution.

  19. Identification and Quantitative Assessment of Uremic Solutes as Inhibitors of Renal Organic Anion Transporters, OAT1 and OAT3.

    Science.gov (United States)

    Hsueh, Chia-Hsiang; Yoshida, Kenta; Zhao, Ping; Meyer, Timothy W; Zhang, Lei; Huang, Shiew-Mei; Giacomini, Kathleen M

    2016-09-06

    One of the characteristics of chronic kidney disease (CKD) is the accumulation of uremic solutes in the plasma. Less is known about the effects of uremic solutes on transporters that may play critical roles in pharmacokinetics. We evaluated the effect of 72 uremic solutes on organic anion transporter 1 and 3 (OAT1 and OAT3) using a fluorescent probe substrate, 6-carboxyfluorescein. A total of 12 and 13 solutes were identified as inhibitors of OAT1 and OAT3, respectively. Several of them inhibited OAT1 or OAT3 at clinically relevant concentrations and reduced the transport of other OAT1/3 substrates in vitro. Review of clinical studies showed that the active secretion of most drugs that are known substrates of OAT1/3 deteriorated faster than the renal filtration in CKD. Collectively, these data suggest that through inhibition of OAT1 and OAT3, uremic solutes contribute to the decline in renal drug clearance in patients with CKD.

  20. Location-based solutions in the experience center

    DEFF Research Database (Denmark)

    Witzner Hansen, Dan; Alapetite, Alexandre; Holdgaard, Nanna

    2009-01-01

    In this paper we present a prototype system for location-based guiding. A user survey has been conducted and the observations are used to support design choices. The prototype allows for both indoor and outdoor navigation at and in the vicinity of the NaturBornholm [1] experience centre in Denmar...... using a combination of Bluetooth, Near field communication (NFC), GPS and QR-codes. Bluetooth, NFC, and GPS are used for location-based information and QR-codes are used to convey user preferences. [1] http://naturbornholm.dk...