A methodology to calibrate water saturation estimated from 4D seismic data

International Nuclear Information System (INIS)

Davolio, Alessandra; Maschio, Célio; José Schiozer, Denis

2014-01-01

Time-lapse seismic data can be used to estimate saturation changes within a reservoir, which is valuable information for reservoir management as it plays an important role in updating reservoir simulation models. The process of updating reservoir properties, history matching, can incorporate estimated saturation changes qualitatively or quantitatively. For quantitative approaches, reliable information from 4D seismic data is important. This work proposes a methodology to calibrate the volume of water in the estimated saturation maps, as these maps can be wrongly estimated due to problems with seismic signals (such as noise, errors associated with data processing and resolution issues). The idea is to condition the 4D seismic data to known information provided by engineering, in this case the known amount of injected and produced water in the field. The application of the proposed methodology in an inversion process (previously published) that estimates saturation from 4D seismic data is presented, followed by a discussion concerning the use of such data in a history matching process. The methodology is applied to a synthetic dataset to validate the results, the main of which are: (1) reduction of the effects of noise and errors in the estimated saturation, yielding more reliable data to be used quantitatively or qualitatively and (2) an improvement in the properties update after using this data in a history matching procedure. (paper)

The Parabolic Variational Inequalities for Variably Saturated Water Flow in Heterogeneous Fracture Networks

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Zuyang Ye

2018-01-01

Full Text Available Fractures are ubiquitous in geological formations and have a substantial influence on water seepage flow in unsaturated fractured rocks. While the matrix permeability is small enough to be ignored during the partially saturated flow process, water seepage in heterogeneous fracture systems may occur in a non-volume-average manner as distinguished from a macroscale continuum model. This paper presents a systematic numerical method which aims to provide a better understanding of the effect of fracture distribution on the water seepage behavior in such media. Based on the partial differential equation (PDE formulations with a Signorini-type complementary condition on the variably saturated water flow in heterogeneous fracture networks, the equivalent parabolic variational inequality (PVI formulations are proposed and the related numerical algorithm in the context of the finite element scheme is established. With the application to the continuum porous media, the results of the numerical simulation for one-dimensional infiltration fracture are compared to the analytical solutions and good agreements are obtained. From the application to intricate fracture systems, it is found that water seepage flow can move rapidly along preferential pathways in a nonuniform fashion and the variably saturated seepage behavior is intimately related to the geometrical characteristics orientation of fractures.

Relation between electric properties and water saturation for hematitic sandstone with frequency

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M. M. Gomaa

2008-06-01

Full Text Available This paper focuses on the effect of water saturation on A. C. electrical conductivity and dielectric constant of fully and partially saturated hematitic sandstone sample (Aswan area, Egypt. The saturation of the sample was changed from partial to full saturation. Complex resistivity measurements at room temperature (~16°C, were performed in the frequency range from 0.1 Hz to 100 KHz. Experimental electrical spectra indicate, generally, that the electrical conductivity and dielectric constant vary strongly with water saturations and frequency. The low frequency electrical conductivity and dielectric constant are mainly controlled by surface conduction and polarization of the electrical double layer. The behaviour of the electrical conductivity and dielectric constant, with increasing water content, were argued to the orientational polarization of bound water for very low saturations, displacement of the excess surface charges for relatively low saturations, and free exchange of excess ions in double layer with the bulk electrolyte and generation of transient diffusion potentials which lag behind the applied field for high saturations.

Ice versus liquid water saturation in simulations of the indian summer monsoon

Science.gov (United States)

Glazer, Russell H.; Misra, Vasubandhu

2018-02-01

At the same temperature, below 0 °C, the saturation vapor pressure (SVP) over ice is slightly less than the SVP over liquid water. Numerical models use the Clausius-Clapeyron relation to calculate the SVP and relative humidity, but there is not a consistent method for the treatment of saturation above the freezing level where ice and mixed-phase clouds may be present. In the context of current challenges presented by cloud microphysics in climate models, we argue that a better understanding of the impact that this treatment has on saturation-related processes like cloud formation and precipitation, is needed. This study explores the importance of the SVP calculation through model simulations of the Indian summer monsoon (ISM) using the regional spectral model (RSM) at 15 km grid spacing. A combination of seasonal and multiyear simulations is conducted with two saturation parameterizations. In one, the SVP over liquid water is prescribed through the entire atmospheric column (woIce), and in another the SVP over ice is used above the freezing level (wIce). When SVP over ice is prescribed, a thermodynamic drying of the middle and upper troposphere above the freezing level occurs due to increased condensation. In the wIce runs, the model responds to the slight decrease in the saturation condition by increasing, relative to the SVP over liquid water only run, grid-scale condensation of water. Increased grid-scale mean seasonal precipitation is noted across the ISM region in the simulation with SVP over ice prescribed. Modification of the middle and upper troposphere moisture results in a decrease in mean seasonal mid-level cloud amount and an increase in high cloud amount when SVP over ice is prescribed. Multiyear simulations strongly corroborate the qualitative results found in the seasonal simulations regarding the impact of ice versus liquid water SVP on the ISM's mean precipitation and moisture field. The mean seasonal rainfall difference over All India between w

Water saturation in shaly sands: logging parameters from log-derived values

International Nuclear Information System (INIS)

Miyairi, M.; Itoh, T.; Okabe, F.

1976-01-01

The methods are presented for determining the relation of porosity to formation factor and that of true resistivity of formation to water saturation, which were investigated through the log interpretation of one of the oil and gas fields of northern Japan Sea. The values of the coefficients ''a'' and ''m'' in porosity-formation factor relation are derived from cross-plot of porosity and resistivity of formation corrected by clay content. The saturation exponent ''n'' is determined from cross-plot of porosity and resistivity index on the assumption that the product of porosity and irreducible water saturation is constant. The relation of porosity to irreducible water saturation is also investigated from core analysis. The new logging parameters determined from the methods, a = 1, m = 2, n = 1.4, improved the values of water saturation by 6 percent in average, and made it easy to distinguish the points which belong to the productive zone and ones belonging to the nonproductive zone

Purification of trona ores by conditioning with an oil-in-water emulsion

Science.gov (United States)

Miller, J. D.; Wang, Xuming; Li, Minhua

2009-04-14

The present invention is a trona concentrate and a process for floating gangue material from trona ore that comprises forming an emulsion, conditioning the trona ore at a high solids content in a saturated trona suspension, and then floating and removing the gangue material. The process for separating trona from gangue materials in trona ore can include emulsifying an oil in an aqueous solution to form an oil-in-water emulsion. A saturated trona suspension having a high solids content can also be formed having trona of a desired particle size. The undissolved trona in the saturated suspension can be conditioned by mixing the saturated suspension and the oil-in-water emulsion to form a conditioning solid suspension of trona and gangue material. A gas can be injected through the conditioning solid suspension to float the gangue material. Thus, the floated gangue material can be readily separated from the trona to form a purified trona concentrate without requirements of additional heat or other expensive processing steps.

Ultrasonic Characterization of Water Saturated Double Porosity Media

Science.gov (United States)

Bai, Ruonan; Tinel, Alain; Alem, Abdellah; Franklin, Hervé; Wang, Huaqing

Wave propagation through a multilayered structure consisting of a water saturated double porosity medium in an aluminum rectangular box immersed in water is studied. By assuming a plane incident wave from water onto the structure, the reflection and transmission coefficients are derived by application of the boundary conditions at each interface. Numerical computations are done for two particular double porosity media, ROBU® and Tobermorite 11 Å, that are assumed to obey Berryman's extension of Biot's theory [Berryman 1995, 2000]. The influence of the thickness of double porosity medium is investigated. To compare experiments to computations, two comparison coefficients Cnum and Cexp are introduced. The theoretical one Cnum is defined as the ratio of the transmission coefficient of the structure to the transmission coefficient of the box filled exclusively with water. The experimental comparison coefficient Cexp is defined as the ratio of the Fourier transforms of the transmitted signals by the box filled with the double porous medium to that of the transmitted signals by the box filled with water. A method of minimization based on a gradient descent algorithm is used to optimize some of the parameters of the double porosity media such as the bulk moduli.

Hydraulic Properties of Porous Media Saturated with Nanoparticle-Stabilized Air-Water Foam

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Xianglei Zheng

2016-12-01

Full Text Available The foam generated by the mixture of air and water has a much higher viscosity and lower mobility than those of pure water or gas that constitutes the air-water foam. The possibility of using the air-water foam as a flow barrier for the purpose of groundwater and soil remediation is explored in this paper. A nanoparticle-stabilized air-water foam was fabricated by vigorously stirring the nano-fluid in pressurized condition. The foam bubble size distribution was analyzed with a microscope. The viscosities of foams generated with the solutions with several nanoparticle concentrations were measured as a function of time. The breakthrough pressure of foam-saturated microfluidic chips and sand columns were obtained. The hydraulic conductivity of a foam-filled sand column was measured after foam breakthrough. The results show that: (1 bubble coalescence and the Ostwald ripening are believed to be the reason of bubble size distribution change; (2 the viscosity of nanoparticle-stabilized foam and the breakthrough pressures decreased with time once the foam was generated; (3 the hydraulic conductivity of the foam-filled sand column was almost two orders of magnitude lower than that of a water-saturated sand column even after the foam-breakthrough. Based on the results in this study, the nanoparticle-stabilized air-water foam could be injected into contaminated soils to generate vertical barriers for temporary hydraulic conductivity reduction.

Seasonal variation in aragonite saturation in surface waters of Puget Sound – a pilot study

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Gregory Pelletier

2018-01-01

Full Text Available A pilot study of sampling, using monthly marine flights over spatially distributed stations, was conducted with the aim to characterize the carbonate system in Puget Sound over a full year-long period. Surface waters of Puget Sound were found to be under-saturated with respect to aragonite during October–March, and super-saturated during April–September. Highest pCO2 and lowest pH occurred during the corrosive October–March period. Lowest pCO2 and highest pH occurred during the super-saturated April–September period. The monthly variations in pCO2 , pH, and aragonite saturation state closely followed the variations in monthly average chlorophyll a. Super-saturated conditions during April–September are likely strongly influenced by photosynthetic uptake of CO2 during the phytoplankton growing season. The relationship between phytoplankton production, the carbonate system, and aragonite saturation state suggests that long-term trends in eutrophication processes may contribute to trends in ocean acidification in Puget Sound

CO2 saturated water as two-phase flow for fouling control in reverse electrodialysis.

Science.gov (United States)

Moreno, J; de Hart, N; Saakes, M; Nijmeijer, K

2017-11-15

When natural feed waters are used in the operation of a reverse electrodialysis (RED) stack, severe fouling on the ion exchange membranes and spacers occurs. Fouling of the RED stack has a strong influence on the gross power density output; which can decrease up to 50%. Moreover, an increase in the pressure loss occurs between the feed water inlet and outlet, increasing the pumping energy and thus decreasing the net power density that can be obtained. In this work, we extensively investigated the use of CO 2 saturated water as two-phase flow cleaning for fouling mitigation in RED using natural feed waters. Experiments were performed in the REDstack research facility located at the Afsluitdijk (the Netherlands) using natural feed waters for a period of 60 days. Two different gas combinations were experimentally investigated, water/air sparging and water/CO 2 (saturated) injection. Air is an inert gas mixture and induces air sparging in the stack. In the case of CO 2 , nucleation, i.e. the spontaneous formation of bubbles, occurs at the spacer filaments due to depressurization of CO 2 saturated water, inducing cleaning. Results showed that stacks equipped with CO 2 saturated water can produce an average net power density of 0.18 W/m 2 under real fouling conditions with minimal pre-treatment and at a low outside temperature of only 8 °C, whereas the stacks equipped with air sparging could only produce an average net power density of 0.04 W/m 2 . Electrochemical impedance spectroscopy measurements showed that the stacks equipped with air sparging increased in stack resistance due to the presence of stagnant bubbles remaining in the stack after every air injection. Furthermore, the introduction of CO 2 gas in the feed water introduces a pH decrease in the system (carbonated solution) adding an additional cleaning effect in the system, thus avoiding the use of environmentally unwanted cleaning chemicals. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All

Landsliding in partially saturated materials

Science.gov (United States)

Godt, J.W.; Baum, R.L.; Lu, N.

2009-01-01

[1] Rainfall-induced landslides are pervasive in hillslope environments around the world and among the most costly and deadly natural hazards. However, capturing their occurrence with scientific instrumentation in a natural setting is extremely rare. The prevailing thinking on landslide initiation, particularly for those landslides that occur under intense precipitation, is that the failure surface is saturated and has positive pore-water pressures acting on it. Most analytic methods used for landslide hazard assessment are based on the above perception and assume that the failure surface is located beneath a water table. By monitoring the pore water and soil suction response to rainfall, we observed shallow landslide occurrence under partially saturated conditions for the first time in a natural setting. We show that the partially saturated shallow landslide at this site is predictable using measured soil suction and water content and a novel unified effective stress concept for partially saturated earth materials. Copyright 2009 by the American Geophysical Union.

Tracer diffusion in compacted, water-saturated bentonite

International Nuclear Information System (INIS)

Bourg, Ian C.; Sposito, Garrison; Bourg, Alain C.M.

2005-01-01

Compacted Na-bentonite clay barriers, widely used in the isolation of solid-waste landfills and other contaminated sites, have been proposed for a similar use in the disposal of high-level radioactive waste. Molecular diffusion through the pore space in these barriers plays a key role in their performance, thus motivating recent measurements of the apparent diffusion coefficient tensor of water tracers in compacted, water-saturated Na-bentonites. In the present study, we introduce a conceptual model in which the pore space of water-saturated bentonite is divided into 'macropore' and 'interlayer nanopore' compartments. With this model we determine quantitatively the relative contributions of pore-network geometry (expressed as a geometric factor) and of the diffusive behavior of water molecules near montmorillonite basal surfaces(expressed as a contrastivity factor) to the apparent diffusion coefficient tensor. Our model predicts, in agreement with experiment, that the mean principal value of the apparent diffusion coefficient tensor follows a single relationship when plotted against the partial montmorillonite dry density (mass of montmorillonite per combined volume of montmorillonite and pore space). Using a single fitted parameter, the mean principal geometric factor, our model successfully describes this relationship for a broad range of bentonite-water system, from dilute gel to highly-compacted bentonite with 80 percent of its pore water in interlayer nanopores

Densities, Viscosities and Derived Thermophysical Properties of Water-Saturated Imidazolium-Based Ionic Liquids.

Science.gov (United States)

Martins, Mónia A R; Neves, Catarina M S S; Kurnia, Kiki A; Carvalho, Pedro J; Rocha, Marisa A A; Santos, Luís M N B F; Pinho, Simão P; Freire, Mara G

2016-01-15

In order to evaluate the impact of the alkyl side chain length and symmetry of the cation on the thermophysical properties of water-saturated ionic liquids (ILs), densities and viscosities as a function of temperature were measured at atmospheric pressure and in the (298.15 to 363.15) K temperature range, for systems containing two series of bis(trifluoromethylsulfonyl)imide-based compounds: the symmetric [C n C n im][NTf 2 ] (with n = 1-8 and 10) and asymmetric [C n C 1 im][NTf 2 ] (with n = 2-5, 7, 9 and 11) ILs. For water-saturated ILs, the density decreases with the increase of the alkyl side chain length while the viscosity increases with the size of the aliphatic tails. The saturation water solubility in each IL was further estimated with a reasonable agreement based on the densities of water-saturated ILs, further confirming that for the ILs investigated the volumetric mixing properties of ILs and water follow a near ideal behaviour. The water-saturated symmetric ILs generally present lower densities and viscosities than their asymmetric counterparts. From the experimental data, the isobaric thermal expansion coefficient and energy barrier were also estimated. A close correlation between the difference in the energy barrier values between the water-saturated and pure ILs and the water content in each IL was found, supporting that the decrease in the viscosity of ILs in presence of water is directly related with the decrease of the energy barrier.

Leaching of radioactive waste forms under saturated and unsaturated flow conditions

International Nuclear Information System (INIS)

Petelka, M.F.

1987-01-01

To predict the environmental impact of shallow land burial sites for radioactive waste, the mobilization and migration of waste nuclides must be estimated. The theoretical understanding that in potential leaching mechanisms leach-rate variations may arise from changes in both moisture content and volumetric flow rate was tested in column flow leach experiments using labeled vermiculite particles as a simulated waste form. As far as possible, conditions of flow rate and solution ion concentration were chosen to roughly approximate expected field conditions. A modified pressure-plate apparatus was developed, tested, and found suitable for the production of steady-state unsaturated conditions with leachate flow. Water content was determined using the gamma-ray attenuation method. The effects of several parameters on leaching were studied, including moisture content and pore velocity. Pore velocity effects were found to be negligible. It was found that the leach rate depends on the fraction of the exposed waste surface that is wetted and varies with the mobile water content in a non-linear fashion. The experimental results indicate that the release rate of radionuclides placed within a properly sited low-level waste disposal site may be two to three times smaller than that predicted assuming saturated conditions. This study was performed using a homogeneous fine-grained synthetic waste form, at room temperature, with a near neutral pH leachant and oxidizing conditions

Potential for saturated ground-water system contamination at the Lawrence Livermore National Laboratory

International Nuclear Information System (INIS)

Stone, R.; Ruggieri, M.R.; Rogers, L.L.; Emerson, D.O.; Buddemeier, R.W.

1982-01-01

A program of hydrogeologic investigation has been carried out to determine the likelihood of contaminant movement to the saturated zone from near the ground surface at Lawrence Livermore National Laboratory (LLNL). A companion survey of potential contaminant sources was also conducted at the LLNL. Water samples from selected LLNL wells were analyzed to test the water quality in the uppermost part of the saturated zone, which is from 14 to 48 m (45 to 158 ft) beneath the surface. Only nitrate and tritium were found in concentrations above natural background. In one well, the nitrate was slightly more concentrated than the drinking water limit. The nitrate source has not been found. The tritium in all ground-water samples from wells was found far less concentrated than the drinking water limit. The extent of infiltration of surface water was traced with environmental tritium. The thickness and stratigraphy of the unsaturated zone beneath the LLNL, and nearby area, was determined with specially constructed wells and boreholes. Well hydrograph analysis indicated where infiltration of surface water reached the saturated ground-water system. The investigation indicates that water infiltrating from the surface, through alluvial deposits, reaches the saturated zone along the course of Arroyo Seco, Arroyo Las Positas, and from the depression near the center of the site where seasonal water accumulates. Several potential contaminant sources were identified, and it is likely that contaminants could move from near the ground surface to the saturated zone beneath LLNL. Additional ground-water sampling and analysis will be performed and ongoing investigations will provide estimates of the speed with which potential contaminants can flow laterally in the saturated zone beneath LLNL. 34 references, 61 figures, 16 tables

Seismic Evaluation of Hydrocarbon Saturation in Deep-Water Reservoirs

Energy Technology Data Exchange (ETDEWEB)

Michael Batzle

2006-04-30

During this last period of the ''Seismic Evaluation of Hydrocarbon Saturation in Deep-Water Reservoirs'' project (Grant/Cooperative Agreement DE-FC26-02NT15342), we finalized integration of rock physics, well log analysis, seismic processing, and forward modeling techniques. Most of the last quarter was spent combining the results from the principal investigators and come to some final conclusions about the project. Also much of the effort was directed towards technology transfer through the Direct Hydrocarbon Indicators mini-symposium at UH and through publications. As a result we have: (1) Tested a new method to directly invert reservoir properties, water saturation, Sw, and porosity from seismic AVO attributes; (2) Constrained the seismic response based on fluid and rock property correlations; (3) Reprocessed seismic data from Ursa field; (4) Compared thin layer property distributions and averaging on AVO response; (5) Related pressures and sorting effects on porosity and their influence on DHI's; (6) Examined and compared gas saturation effects for deep and shallow reservoirs; (7) Performed forward modeling using geobodies from deepwater outcrops; (8) Documented velocities for deepwater sediments; (9) Continued incorporating outcrop descriptive models in seismic forward models; (10) Held an open DHI symposium to present the final results of the project; (11) Relations between Sw, porosity, and AVO attributes; (12) Models of Complex, Layered Reservoirs; and (14) Technology transfer Several factors can contribute to limit our ability to extract accurate hydrocarbon saturations in deep water environments. Rock and fluid properties are one factor, since, for example, hydrocarbon properties will be considerably different with great depths (high pressure) when compared to shallow properties. Significant over pressure, on the other hand will make the rocks behave as if they were shallower. In addition to the physical properties, the scale and

Stability of infinite slopes under transient partially saturated seepage conditions

Science.gov (United States)

Godt, Jonathan W.; ŞEner-Kaya, BaşAk; Lu, Ning; Baum, Rex L.

2012-05-01

Prediction of the location and timing of rainfall-induced shallow landslides is desired by organizations responsible for hazard management and warnings. However, hydrologic and mechanical processes in the vadose zone complicate such predictions. Infiltrating rainfall must typically pass through an unsaturated layer before reaching the irregular and usually discontinuous shallow water table. This process is dynamic and a function of precipitation intensity and duration, the initial moisture conditions and hydrologic properties of the hillside materials, and the geometry, stratigraphy, and vegetation of the hillslope. As a result, pore water pressures, volumetric water content, effective stress, and thus the propensity for landsliding vary over seasonal and shorter time scales. We apply a general framework for assessing the stability of infinite slopes under transient variably saturated conditions. The framework includes profiles of pressure head and volumetric water content combined with a general effective stress for slope stability analysis. The general effective stress, or suction stress, provides a means for rigorous quantification of stress changes due to rainfall and infiltration and thus the analysis of slope stability over the range of volumetric water contents and pressure heads relevant to shallow landslide initiation. We present results using an analytical solution for transient infiltration for a range of soil texture and hydrological properties typical of landslide-prone hillslopes and show the effect of these properties on the timing and depth of slope failure. We follow by analyzing field-monitoring data acquired prior to shallow landslide failure of a hillside near Seattle, Washington, and show that the timing of the slide was predictable using measured pressure head and volumetric water content and show how the approach can be used in a forward manner using a numerical model for transient infiltration.

[The water content reference material of water saturated octanol].

Science.gov (United States)

Wang, Haifeng; Ma, Kang; Zhang, Wei; Li, Zhanyuan

2011-03-01

The national standards of biofuels specify the technique specification and analytical methods. A water content certified reference material based on the water saturated octanol was developed in order to satisfy the needs of the instrument calibration and the methods validation, assure the accuracy and consistency of results in water content measurements of biofuels. Three analytical methods based on different theories were employed to certify the water content of the reference material, including Karl Fischer coulometric titration, Karl Fischer volumetric titration and quantitative nuclear magnetic resonance. The consistency of coulometric and volumetric titration was achieved through the improvement of methods. The accuracy of the certified result was improved by the introduction of the new method of quantitative nuclear magnetic resonance. Finally, the certified value of reference material is 4.76% with an expanded uncertainty of 0.09%.

Predicting the occurrence of mixed mode failure associated with hydraulic fracturing, part 2 water saturated tests

Energy Technology Data Exchange (ETDEWEB)

Bauer, Stephen J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Broome, Scott Thomas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Choens, Charles [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Barrow, Perry Carl [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-09-14

Seven water-saturated triaxial extension experiments were conducted on four sedimentary rocks. This experimental condition was hypothesized more representative of that existing for downhole hydrofracture and thus it may improve our understanding of the phenomena. In all tests the pore pressure was 10 MPa and confirming pressure was adjusted to achieve tensile and transitional failure mode conditions. Using previous work in this LDRD for comparison, the law of effective stress is demonstrated in extension using this sample geometry. In three of the four lithologies, no apparent chemo-mechanical effect of water is apparent, and in the fourth lithology test results indicate some chemo-mechanical effect of water.

Discontinuities in hygroscopic growth below and above water saturation for laboratory surrogates of oligomers in organic atmospheric aerosols

Directory of Open Access Journals (Sweden)

N. Hodas

2016-10-01

Full Text Available Discontinuities in apparent hygroscopicity below and above water saturation have been observed for organic and mixed organic–inorganic aerosol particles in both laboratory studies and in the ambient atmosphere. However, uncertainty remains regarding the factors that contribute to observations of low hygroscopic growth below water saturation but enhanced cloud condensation nuclei (CCN activity for a given aerosol population. Utilizing laboratory surrogates for oligomers in atmospheric aerosols, we explore the extent to which such discontinuities are influenced by organic component molecular mass and viscosity, non-ideal thermodynamic interactions between aerosol components, and the combination of these factors. Measurements of hygroscopic growth under subsaturated conditions and the CCN activity of aerosols comprised of polyethylene glycol (PEG with average molecular masses ranging from 200 to 10 000 g mol−1 and mixtures of PEG with ammonium sulfate (AS were conducted. Experimental results are compared to calculations of hygroscopic growth at thermodynamic equilibrium conducted with the Aerosol Inorganic Organic Mixtures Functional groups Activity Coefficients (AIOMFAC model, and the potential influence of kinetic limitations on observed water uptake was further explored through estimations of water diffusivity in the PEG oligomers. Particle-phase behavior, including the prevalence of liquid–liquid phase separation (LLPS, was also modeled with AIOMFAC. Under subsaturated relative humidity (RH conditions, we observed little variability in hygroscopic growth across PEG systems with different molecular masses; however, an increase in CCN activity with increasing PEG molecular mass was observed. This effect is most pronounced for PEG–AS mixtures, and, in fact, an enhancement in CCN activity was observed for the PEG10000–AS mixture as compared to pure AS, as evidenced by a 15 % reduction in critical activation diameter at a

Natural gas adsorption on coal in anhydrous and in water saturated conditions: study of the adsorbed quantities and of the isotopic fractionation

International Nuclear Information System (INIS)

Caja, M.

2000-02-01

In order to understand the influence of adsorption in the migration of natural gas in sedimentary basins. we have developed an experimental device to measure the quantity of gas adsorbed on organic matter. We quantify the isotopic and chemical fractionation due to adsorption of natural gas on coal at representative gas field conditions (20 - 200 deg C and 1 - 1000 bar). These effects are investigated for gas / solid systems and for gas dissolved in water/water saturated solid systems. The solid sample considered in this work is a natural coal of Carboniferous age, taken from a mine in Lorraine, France. Its maturity corresponds to the end of the diagenesis zone. A first set of high pressure methane adsorption experiments on dry coal are compared with measurements done by another laboratory on the same solid. This allowed us to validate the experimental procedure. This measurements performed in the presence of water have shown that methane adsorption is significant even in presence of water. We have developed a simple adsorption model (Langmuir model in which fugacity is used in stead of partial pressure) in order to represent this phenomena. For a depth profile we compare the part of methane adsorbed on sedimentary rocks organic matter to methane dissolved in pore water. A second set of experiments realised on a multicomponent gas (C1, C2, C3, C4, CO 2 ) shows a preferential adsorption of carbon dioxide, but no significant fractionation on hydrocarbon gases of the mixture has been observed. Adsorption experiments of methane on dry medium and on water saturated medium yield on the same result: adsorption equilibrium do not induce a significant isotopic fractionation between 13 CH 4 and 12 CH 4 . However, we observe a significant fractionation during gas desorption. The interpretation is that we are not at equilibrium and diffusion phenomena is superimposed on adsorption. From this study two important geological consequences can be drawn. First. for rocks containing

Relationship between 222Rn concentration in soil water and degree of saturation

International Nuclear Information System (INIS)

Hamada, Hiromasa; Komae, Takami

1996-01-01

The object of the researches an analyzing downward flow to groundwater using 222 Rn concentration in water as an indicator has been saturated flow. However, when groundwater table is low, downward flow from surface is unsaturated flow. In this paper, the authors represented the relationship between 222 Rn concentration in soil water and degree of saturation, and measured the vertical distributions of 222 Rn concentrations in groundwater and 222 Rn concentration in water table in the fields. As the results, it was found that 222 Rn concentrations in the vicinity of groundwater table decreased by unsaturated downward flow. Moreover, from the variation of 222 Rn concentrations in groundwater table, it was possible to show the occurrence of the unsaturated downward flow by paddy fields irrigation, i.e., the downward flow of the soil water pushed out by irrigation water, the unsaturated percolation in the irrigation period, and the redistribution of the soil water after the release of ponding water. The degree of saturation in downward flow was calculated to be about 50% from 222 Rn concentrations in the irrigation period and in the non-irrigation period. It was deduced that the value was within reasonable range considering the difference of the hydraulic conductivities between of the upper layer and of the lower layer. These results proved that the relationship between 222 Rn concentrations in soil water and degree of saturation represented by the authors was reasonable and that the analytical method using 222 Rn concentrations in groundwater table as an indicator was useful 10 analyze the actual stale of unsaturated downward flow. (author)

Characteristics of soil under variations in clay, water saturation, and water flow rates, and the implications upon soil remediation

International Nuclear Information System (INIS)

Aikman, M.; Mirotchnik, K.; Kantzas, A.

1997-01-01

A potential remediation method for hydrocarbon contaminated soils was discussed. The new method was based on the use of proven and economic petroleum reservoir engineering methods for soil remediation. The methods that were applied included water and gas displacement methods together with horizontal boreholes as the flow inlet and outlets. This system could be used in the case of spills that seep beneath a plant or other immovable infrastructure which requires in-situ treatment schemes to decontaminate the soil. A study was conducted to characterize native soils and water samples from industrial plants in central Alberta and Sarnia, Ontario and to determine the variables that impact upon the flow conditions of synthetic test materials. The methods used to characterize the soils included X-Ray computed tomographic analysis, grain size and density measurements, and X-Ray diffraction. Clay content, initial water saturation, and water and gas flow rate were the variables that impacted on the flow conditions

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

Determination of water saturation in subsurface earth formations adjacent well boreholes

International Nuclear Information System (INIS)

Scott, Hubert D.

1982-01-01

There is provided a method of determining the water saturation of an earth formation surrounding a well borehole, comprising the steps of: (a) bombarding the earth formation with repetitive pulses of fast neutrons which are slowed down and thereafter engage in neutron capture reactions with materials in the vicinity of the borehole; (b) obtaining by use of a germanium gamma ray detector gamma ray spectra of the materials in the vicinity of the borehole; (c) obtaining from the gamma ray spectra a measure of the relative presence of chlorine to that of hydrogen in the formation; (d) obtaining a measure of apparent formation water salinity from the measure of relative presence of chlorine to hydrogen in the formation; and (e) obtaining the water saturation of the formation utilizing the apparent formation water salinity

Simulation of gas hydrogen diffusion through partially water saturated mono-modal materials

International Nuclear Information System (INIS)

Boher, C.; Lorente, S.; Frizon, F.; Bart, F.

2012-01-01

Concerning the disposal of nuclear wastes, it is important to design concrete envelopes with pore networks that allow the diffusion of hydrogen towards the outside. This work documents the relationship between geo-polymers, which are materials with a quasi mono-modal pore network, and their gaseous diffusivity capacities. Using a mono-modal material allows studying a specific pore size contribution to gaseous diffusion. The pore network is characterized by mercury porosimetry. These experimental results are used as data in a model named MOHYCAN. The modeling work consists of creating a virtual pore network. Then, water layers are deposited in this network to simulate variable water saturation levels. Finally hydrogen is transported through the virtual network using a combination of ordinary diffusion and Knudsen diffusion. MOHYCAN calculates the hydrogen diffusion coefficient for water saturation degree from 0% to 100%. The impacts of the pore network arrangement or the pore network discretization have been studied. The results are, for a quasi mono-modal material: -) the diffusion coefficient is not sensitive to different virtual pore network arrangement; -) the diffusion coefficient values have a sharp drop at specific water saturation (this is due to the water saturation of the main and unique pore family); -) a 2 pores family based model is sufficient to represent the pore network. Theses observations will not be valid if we consider a material with a large pore size distribution, like cementitious materials

Soil Water Retention and Relative Permeability for Conditions from Oven-Dry to Full Saturation

Energy Technology Data Exchange (ETDEWEB)

Zhang, Z. F.

2011-11-04

Common conceptual models for unsaturated flow often rely on the oversimplified representation of medium pores as a bundle of cylindrical capillaries and assume that the matric potential is attributed to the capillary force only. The adsorptive surface forces are ignored. It is often assumed that aqueous flow is negligible when a soil is near or at the residual water content. These models are successful at high and medium water contents but often give poor results at low water contents. These models do not apply to conditions at which the water content is less than the residual water content. We extend the lower bound of existing water-retention functions and conductivity models from residual water content to the oven-dry condition (i.e., zero water content) by defining a state-dependent, residual-water content for a soil drier than a critical value. Furthermore, a hydraulic conductivity model for smooth uniform spheres was modified by introducing a correction factor to describe the film flow-induced hydraulic conductivity for natural porous media. The total unsaturated hydraulic conductivity is the sum of those due to capillary and film flow. The extended retention and conductivity models were verified measurements. Results show that, when the soil is at high and intermediate water content, there is no difference between the un-extended and the extended models; when the soil is at low water content, the un-extended models overestimate the water content but underestimate the conductivity. The extended models match the retention and conductivity measurements well.

Partially to fully saturated flow through smooth, clean, open fractures: qualitative experimental studies

Science.gov (United States)

Jones, Brendon R.; Brouwers, Luke B.; Dippenaar, Matthys A.

2018-05-01

Fractures are both rough and irregular but can be expressed by a simple model concept of two smooth parallel plates and the associated cubic law governing discharge through saturated fractures. However, in natural conditions and in the intermediate vadose zone, these assumptions are likely violated. This paper presents a qualitative experimental study investigating the cubic law under variable saturation in initially dry free-draining discrete fractures. The study comprised flow visualisation experiments conducted on transparent replicas of smooth parallel plates with inlet conditions of constant pressure and differing flow rates over both vertical and horizontal inclination. Flow conditions were altered to investigate the influence of intermittent and continuous influx scenarios. Findings from this research proved, for instance, that saturated laminar flow is not likely achieved, especially in nonhorizontal fractures. In vertical fractures, preferential flow occupies the minority of cross-sectional area despite the water supply. Movement of water through the fractured vadose zone therefore becomes a matter of the continuity principle, whereby water should theoretically be transported downward at significantly higher flow rates given the very low degree of water saturation. Current techniques that aim to quantify discrete fracture flow, notably at partial saturation, are questionable. Inspired by the results of this study, it is therefore hypothetically improbable to achieve saturation in vertical fractures under free-draining wetting conditions. It does become possible under extremely excessive water inflows or when not free-draining; however, the converse is not true, as a wet vertical fracture can be drained.

Partially to fully saturated flow through smooth, clean, open fractures: qualitative experimental studies

Science.gov (United States)

Jones, Brendon R.; Brouwers, Luke B.; Dippenaar, Matthys A.

2017-11-01

Fractures are both rough and irregular but can be expressed by a simple model concept of two smooth parallel plates and the associated cubic law governing discharge through saturated fractures. However, in natural conditions and in the intermediate vadose zone, these assumptions are likely violated. This paper presents a qualitative experimental study investigating the cubic law under variable saturation in initially dry free-draining discrete fractures. The study comprised flow visualisation experiments conducted on transparent replicas of smooth parallel plates with inlet conditions of constant pressure and differing flow rates over both vertical and horizontal inclination. Flow conditions were altered to investigate the influence of intermittent and continuous influx scenarios. Findings from this research proved, for instance, that saturated laminar flow is not likely achieved, especially in nonhorizontal fractures. In vertical fractures, preferential flow occupies the minority of cross-sectional area despite the water supply. Movement of water through the fractured vadose zone therefore becomes a matter of the continuity principle, whereby water should theoretically be transported downward at significantly higher flow rates given the very low degree of water saturation. Current techniques that aim to quantify discrete fracture flow, notably at partial saturation, are questionable. Inspired by the results of this study, it is therefore hypothetically improbable to achieve saturation in vertical fractures under free-draining wetting conditions. It does become possible under extremely excessive water inflows or when not free-draining; however, the converse is not true, as a wet vertical fracture can be drained.

Changes in the composition and properties of Ashalchinskoye bitumen-saturated sandstones when exposed to water vapor

Science.gov (United States)

Korolev, E.; Eskin, A.; Kolchugin, A.; Morozov, V.; Khramchenkov, M.; Gabdelvalieva, R.

2018-05-01

Ashalchinskoye bitumen deposit is an experimental platform for testing technology of high-viscosity oil extraction from reservoir rocks. Last time for enhanced of oil recovery in reservoir used pressurization a water vapor with a temperature of ∼ 180 ° C (SAGD technology). However, what happens in sandstone reservoir is little known. We did a study of the effects of water vapor on the structural components of bitumen saturated sandstone. In paper were studied the rock samples at base condition and after one week exposure by water vapour. The thermal analysis showed that steaming helps to removes light and middle oil fractions with a boiling point up to 360 ° C from oil saturated sandstones. Content of heavy oil fractions virtually unchanged. Studying the composition of water extractions of samples showed that the process of aquathermolysis of oil is accompanied by a lowering of the pH of the pore solution from 7.4 to 6.5 and rise content in several times of mobile cations Ca2+, Mg2+ and HCO3 -, SO4 2- anions. Follows from this that the thermal steam effect by bitumen saturated sandstones leads to partial oxidation of hydrocarbons with to form a carbon dioxide. The source of sulfate ions were oxidized pyrite aggregates. Due to the increasing acidity of condensed water, which fills the pore space of samples, pore fluid becomes aggressive to calcite and dolomite cement of bitumen saturated sandstones. As a result of the dissolution of carbonate cement the pore fluid enriched by calcium and magnesium cations. Clearly, that the process is accompanied by reduction of contact strength between fragments of minerals and rocks. Resulting part of compounds is separated from the outer side of samples and falls to bottom of water vapor container. Decreasing the amount of calcite and dolomite anions in samples in a steam-treated influence is confirmed by X-Ray analysis. X-Ray analysis data of study adscititious component of rocks showed that when influenced of water vapor to

Infiltration behaviour of elemental mercury DNAPL in fully and partially water saturated porous media

Science.gov (United States)

D'Aniello, Andrea; Hartog, Niels; Sweijen, Thomas; Pianese, Domenico

2018-02-01

Mercury is a contaminant of global concern due to its harmful effects on human health and for the detrimental consequences of its release in the environment. Sources of liquid elemental mercury are usually anthropogenic, such as chlor-alkali plants. To date insight into the infiltration behaviour of liquid elemental mercury in the subsurface is lacking, although this is critical for assessing both characterization and remediation approaches for mercury DNAPL contaminated sites. Therefore, in this study the infiltration behaviour of elemental mercury in fully and partially water saturated systems was investigated using column experiments. The properties affecting the constitutive relations governing the infiltration behaviour of liquid Hg0, and PCE for comparison, were determined using Pc(S) experiments with different granular porous media (glass beads and sands) for different two- and three-phase configurations. Results showed that, in water saturated porous media, elemental mercury, as PCE, acted as a non-wetting fluid. The required entry head for elemental mercury was higher (from about 5 to 7 times). However, due to the almost tenfold higher density of mercury, the required NAPL entry heads of 6.19 cm and 12.51 cm for mercury to infiltrate were 37.5% to 20.7% lower than for PCE for the same porous media. Although Leverett scaling was able to reproduce the natural tendency of Hg0 to be more prone than PCE to infiltrate in water saturated porous media, it considerably underestimated Hg0 infiltration capacity in comparison with the experimental results. In the partially water saturated system, in contrast with PCE, elemental mercury also acted as a nonwetting fluid, therefore having to overcome an entry head to infiltrate. The required Hg0 entry heads (10.45 and 15.74 cm) were considerably higher (68.9% and 25.8%) than for the water saturated porous systems. Furthermore, in the partially water saturated systems, experiments showed that elemental mercury displaced

Flow of gasoline-in-water microemulsion through water-saturated soil columns

International Nuclear Information System (INIS)

Ouyang, Y.; Mansell, R.S.; Rhue, R.D.

1995-01-01

Much consideration has been given to the use of surfactants to clean up nonaqueous phase liquids (NAPLs) from contaminated soil and ground water. Although this emulsification technique has shown significant potential for application in environmental remediation practices, a major obstacle leading to low washing efficiency is the potential formation of macroemulsion with unfavorable flow characteristics in porous media. This study investigated influences of the flow of leaded-gasoline-in-water (LG/W) microemulsion upon the transport of gasoline and lead (Pb) species in water-saturated soil columns. Two experiments were performed: (1) the immiscible displacement of leaded gasoline and (2) the miscible displacement of LG/W microemulsion through soil columns, followed by sequentially flushing with NaCl solution and a water/surfactant/cosurfactant (W/S/CoS) mixture. Comparison of breakthrough curves (BTC) for gasoline between the two experiments shows that about 90% of gasoline and total Pb were removed from the soil columns by NaCl solution in the LG/W microemulsion experiment as compared to 40% removal of gasoline and 10% removal of total Pb at the same process in the leaded gasoline experiment. Results indicate that gasoline and Pb species moved much more effectively through soil during miscible flow of LG/W microemulsion than during immiscible flow of leaded gasoline. In contrast to the adverse effects of macroemulsion on the transport of NAPLs, microemulsion was found to enhance the transport of gasoline through water-saturated soil. Mass balance analysis shows that the W/S/CoS mixture had a high capacity for removing residual gasoline and Pb species from contaminated soil. Comparison of water-pressure differences across the soil columns for the two experiments indicates that pore clogging by gasoline droplets was greatly minimized in the LG/W microemulsion experiment

Cibicidodes Pachyderma B/Ca as a Shalow Water Carbonate Saturation State Proxy

Science.gov (United States)

Wojcieszek, D. E.; Flower, B. P.; Moyer, R. P.; Byrne, R. H.

2012-12-01

Since the industrial revolution, the oceans have absorbed about 25% of anthropogenic CO2 emissions to the atmosphere, leading to a decrease in seawater pH (termed ocean acidification: OA) as well as many associated effects, including decreased saturation states. Assessment of the effects of OA on marine ecosystems is presently based on chemistry and its impact on biota over much longer time scales can provide essential context for likely future consequences of OA. Reliable oceanic paleo-proxies for influential chemical variables such as pH and carbonate saturation state are crucial components for examining ancient environments affected by OA. Addition of CO2 to seawater leads to not only decreases in seawater pH and saturation state, but also the extent to which boron (B) is incorporated into CaCO3 during biotic calcification. Consequently, the abundance of B in calcite could reflect pH and/or saturation state of the water in which calcification occurred. Recent studies indicate a linear relationship between the ratio of boron to calcium (B/Ca) in benthic foraminifera shells ( Cibicidoides wuellerstorfi, C. mundulus) and the degree of carbonate saturation (Δ[CO32-]), defined as a difference between [CO32-]in situ and [CO32-]saturation. However, the observed relationship between B/Ca and Δ[CO32-] was only established for depths >1000m. Thus, since OA most immediately affects the upper 1000 m of the water column, a reliable shallow water (chemistry proxy is desirable. We are testing the utility of B/Ca in Cibicidoides pachyderma as a shallow water Δ[CO32-] proxy. C. pachyderma is an epibenthic species and therefore records the composition of bottom, rather than interstitial, waters. It usually inhabits depths between 200 and 1000 m, and is a common species in the Gulf of Mexico. The gently sloping West Florida Shelf (WFS) is an excellent setting for this kind of study as it provides a full range of depths habitable by C.pachyderma. Nine surface sediment samples

Explosion Amplitude Reduction due to Fractures in Water-Saturated and Dry Granite

Science.gov (United States)

Stroujkova, A. F.; Leidig, M.; Bonner, J. L.

2013-12-01

Empirical observations made at the Semipalatinsk Test Site suggest that nuclear tests in the fracture zones left by previous explosions ('repeat shots') show reduced seismic amplitudes compared to the nuclear tests in virgin rocks. Likely mechanisms for the amplitude reduction in the repeat shots include increased porosity and reduced strength and elastic moduli, leading to pore closing and frictional sliding. Presence of pore water significantly decreases rock compressibility and strength, thus affecting seismic amplitudes. A series of explosion experiments were conducted in order to define the physical mechanism responsible for the amplitude reduction and to quantify the degree of the amplitude reduction in fracture zones of previously detonated explosions. Explosions in water-saturated granite were conducted in central New Hampshire in 2011 and 2012. Additional explosions in dry granite were detonated in Barre, VT in 2013. The amplitude reduction is different between dry and water-saturated crystalline rocks. Significant reduction in seismic amplitudes (by a factor of 2-3) in water-saturated rocks was achieved only when the repeat shot was detonated in the extensive damage zone created by a significantly larger (by a factor of 5) explosion. In case where the first and the second explosions were similar in yield, the amplitude reduction was relatively modest (5-20%). In dry rocks the amplitude reduction reached a factor of 2 even in less extensive damage zones. In addition there are differences in frequency dependence of the spectral amplitude ratios between explosions in dry and water-saturated rocks. Thus the amplitude reduction is sensitive to the extent of the damage zone as well as the pore water content.

Experimental techniques for characterising water in wood covering the range from dry to fully water-saturated

DEFF Research Database (Denmark)

Thybring, Emil Engelund; Kymäläinen, Maija; Rautkari, Lauri

2018-01-01

focuses on selected experimental techniques that can give deeper insights into various aspects of water in wood in the entire moisture domain from dry to fully water-saturated. These techniques fall into three broad categories: (1) gravimetric techniques that determine how much water is absorbed, (2...

Flow and fracture in water-saturated, unconstrained granular beds

Directory of Open Access Journals (Sweden)

Germán eVaras

2015-06-01

Full Text Available The injection of gas in a liquid-saturated granular bed gives rise to a wide variety of invasion patterns. Many studies have focused on constrained porous media, in which the grains are fixed in the bed and only the interstitial fluid flows when the gas invades the system. With a free upper boundary, however, the grains can be entrained by the ascending gas or fluid motion, and the competition between the upward motion of grains and sedimentation leads to new patterns. We propose a brief review of the experimental investigation of the dynamics of air rising through a water-saturated, unconstrained granular bed, in both two and three dimensions. After describing the invasion pattern at short and long time, a tentative regime-diagram is proposed. We report original results showing a dependence of the fluidized zone shape, at long times, on the injection flow rate and grain size. A method based on image analysis makes it possible to detect not only the fluidized zone profile in the stationary regime, but also to follow the transient dynamics of its formation. Finally, we describe the degassing dynamics inside the fluidized zone, in the stationary regime. Depending on the experimental conditions, regular bubbling, continuous degassing, intermittent regime or even spontaneous flow-to-fracture transition are observed.

Regional Quasi-Three-Dimensional Unsaturated-Saturated Water Flow Model Based on a Vertical-Horizontal Splitting Concept

Directory of Open Access Journals (Sweden)

Yan Zhu

2016-05-01

Full Text Available Due to the high nonlinearity of the three-dimensional (3-D unsaturated-saturated water flow equation, using a fully 3-D numerical model is computationally expensive for large scale applications. A new unsaturated-saturated water flow model is developed in this paper based on the vertical/horizontal splitting (VHS concept to split the 3-D unsaturated-saturated Richards’ equation into a two-dimensional (2-D horizontal equation and a one-dimensional (1-D vertical equation. The horizontal plane of average head gradient in the triangular prism element is derived to split the 3-D equation into the 2-D equation. The lateral flow in the horizontal plane of average head gradient represented by the 2-D equation is then calculated by the water balance method. The 1-D vertical equation is discretized by the finite difference method. The two equations are solved simultaneously by coupling them into a unified nonlinear system with a single matrix. Three synthetic cases are used to evaluate the developed model code by comparing the modeling results with those of Hydrus1D, SWMS2D and FEFLOW. We further apply the model to regional-scale modeling to simulate groundwater table fluctuations for assessing the model applicability in complex conditions. The proposed modeling method is found to be accurate with respect to measurements.

Quantitative 1D saturation profiles on chalk by NMR

DEFF Research Database (Denmark)

Olsen, Dan; Topp, Simon; Stensgaard, Anders

1996-01-01

Quantitative one-dimensional saturation profiles showing the distribution of water and oil in chalk core samples are calculated from NMR measurements utilizing a 1D CSI spectroscopy pulse sequence. Saturation profiles may be acquired under conditions of fluid flow through the sample. Results reveal...

Uniqueness of Specific Interfacial Area–Capillary Pressure–Saturation Relationship Under Non-Equilibrium Conditions in Two-Phase Porous Media Flow

KAUST Repository

Joekar-Niasar, Vahid

2012-02-23

The capillary pressure-saturation (P c-S w) relationship is one of the central constitutive relationships used in two-phase flow simulations. There are two major concerns regarding this relation. These concerns are partially studied in a hypothetical porous medium using a dynamic pore-network model called DYPOSIT, which has been employed and extended for this study: (a) P c-S w relationship is measured empirically under equilibrium conditions. It is then used in Darcy-based simulations for all dynamic conditions. This is only valid if there is a guarantee that this relationship is unique for a given flow process (drainage or imbibition) independent of dynamic conditions; (b) It is also known that P c-S w relationship is flow process dependent. Depending on drainage and imbibition, different curves can be achieved, which are referred to as "hysteresis". A thermodynamically derived theory (Hassanizadeh and Gray, Water Resour Res 29: 3389-3904, 1993a) suggests that, by introducing a new state variable, called the specific interfacial area (a nw, defined as the ratio of fluid-fluid interfacial area to the total volume of the domain), it is possible to define a unique relation between capillary pressure, saturation, and interfacial area. This study investigates these two aspects of capillary pressure-saturation relationship using a dynamic pore-network model. The simulation results imply that P c-S w relation not only depends on flow process (drainage and imbibition) but also on dynamic conditions for a given flow process. Moreover, this study attempts to obtain the first preliminary insights into the global functionality of capillary pressure-saturation-interfacial area relationship under equilibrium and non-equilibrium conditions and the uniqueness of P c-S w-a nw relationship. © 2012 The Author(s).

Experimental and numerical study on thermal conductivity of partially saturated unconsolidated sands

Science.gov (United States)

Lee, Youngmin; Keehm, Youngseuk; Kim, Seong-Kyun; Shin, Sang Ho

2016-04-01

A class of problems in heat flow applications requires an understanding of how water saturation affects thermal conductivity in the shallow subsurface. We conducted a series of experiments using a sand box to evaluate thermal conductivity (TC) of partially saturated unconsolidated sands under varying water saturation (Sw). We first saturated sands fully with water and varied water saturation by drainage through the bottom of the sand box. Five water-content sensors were integrated vertically into the sand box to monitor water saturation changes and a needle probe was embedded to measure thermal conductivity of partially saturated sands. The experimental result showed that thermal conductivity decreases from 2.5 W/mK for fully saturated sands to 0.7 W/mK when water saturation is 5%. We found that the decreasing trend is quite non-linear: highly sensitive at very high and low water saturations. However, the boundary effects on the top and the bottom of the sand box seemed to be responsible for this high nonlinearity. We also found that the determination of water saturation is quite important: the saturation by averaging values from all five sensors and that from the sensor at the center position, showed quite different trends in the TC-Sw domain. In parallel, we conducted a pore-scale numerical modeling, which consists of the steady-state two-phase Lattice-Boltzmann simulator and FEM thermal conduction simulator on digital pore geometry of sand aggregation. The simulation results showed a monotonous decreasing trend, and are reasonably well matched with experimental data when using average water saturations. We concluded that thermal conductivity would decrease smoothly as water saturation decreases if we can exclude boundary effects. However, in dynamic conditions, i.e. imbibition or drainage, the thermal conductivity might show hysteresis, which can be investigated with pore-scale numerical modeling with unsteady-state two-phase flow simulators in our future work.

Influence of the tension-saturated zone on contaminant migration in shallow water-table regimes

International Nuclear Information System (INIS)

Gillham, R.W.

1982-01-01

Groundwater discharge represents a major pathway for the return to the biosphere of contaminants that are released to the subsurface environment. An understanding of the transport processes in groundwater discharge zones is therefore an important consideration in pathway analyses associated with the environmental assessment of proposed waste-management facilities. Shallow water tables are a common characteristic of groundwater discharge zones, particularly in humid climatic regions. In this paper, the results of field tests, laboratory tests and numerical simulations are used to show that under shallow water-table conditions, the zone of tension saturation can result in a rapid and highly disproportionate water-table response to precipitation. It is further shown that this response can result in complex migration patterns that would not be predicted by the classical approaches to solute transport modelling and that the response could result in large and highly transient inputs to surface water

Sector-condition-based results for adaptive control and synchronization of chaotic systems under input saturation

International Nuclear Information System (INIS)

Iqbal, Muhammad; Rehan, Muhammad; Hong, Keum-Shik; Khaliq, Abdul; Saeed-ur-Rehman

2015-01-01

This paper addresses the design of adaptive feedback controllers for two problems (namely, stabilization and synchronization) of chaotic systems with unknown parameters by considering input saturation constraints. A novel generalized sector condition is developed to deal with the saturation nonlinearities for synthesizing the nonlinear and the adaptive controllers for the stabilization and synchronization control objectives. By application of the proposed sector condition and rigorous regional stability analysis, control and adaptation laws are formulated to guarantee local stabilization of a nonlinear system under actuator saturation. Further, simple control and adaptation laws are developed to synchronize two chaotic systems under uncertain parameters and input saturation nonlinearity. Numerical simulation results for Rössler and FitzHugh–Nagumo models are provided to demonstrate the effectiveness of the proposed adaptive stabilization and synchronization control methodologies

Exact expression for the effective acoustics of patchy-saturated rocks

NARCIS (Netherlands)

Vogelaar, B.; Smeulders, D.M.J.; Harris, J.

2010-01-01

Seismic effects of a partially gas-saturated subsurface have been known for many years. For example, patches of nonuniform saturation occur at the gas-oil and gas-water contacts in hydrocarbon reservoirs. Open-pore boundary conditions are applied to the quasi-static Biot equations of poroelasticity

Water hammer phenomena occurring in nuclear power installations while filling horizontal pipe containing saturated steam with liquid

Energy Technology Data Exchange (ETDEWEB)

Selivanov, Y.F.; Kirillov, P.L.; Yefanov, A.D. [Institute of Physics and Power Engineering, Obninsk (Russian Federation)

1995-09-01

The potentiality of the water hammer occurrence in nuclear reactor loop components has been considered under the conditions of filling a steam-containing pipeline leg involving horizontal and vertical sections with liquid subcooled to the saturation temperature. As a result of free discharging from the tank, the liquid enters the horizontal pipeline. When the liquid slug formation in the pipeline is fulfilled. The pressure drop being occurred in steam flowing along the pipelines causes the liquid slug to move to the pipeline inlet. When the liquid slug decelerates, a water hammer occurs. This mechanism of water hammer occurrence is tested by experiments. The regimes of the occurrence of multiple considerable water hammers were identified.

Water hammer phenomena occurring in nuclear power installations while filling horizontal pipe containing saturated steam with liquid

International Nuclear Information System (INIS)

Selivanov, Y.F.; Kirillov, P.L.; Yefanov, A.D.

1995-01-01

The potentiality of the water hammer occurrence in nuclear reactor loop components has been considered under the conditions of filling a steam-containing pipeline leg involving horizontal and vertical sections with liquid subcooled to the saturation temperature. As a result of free discharging from the tank, the liquid enters the horizontal pipeline. When the liquid slug formation in the pipeline is fulfilled. The pressure drop being occurred in steam flowing along the pipelines causes the liquid slug to move to the pipeline inlet. When the liquid slug decelerates, a water hammer occurs. This mechanism of water hammer occurrence is tested by experiments. The regimes of the occurrence of multiple considerable water hammers were identified

Measurement of water transport from saturated pumice aggregates to hardening cement paste

DEFF Research Database (Denmark)

Lura, Pietro; Bentz, Dale; Lange, David A.

2006-01-01

In internal water curing of High Performance Concrete, it is fundamental to know how and when the water contained in the internal curing agent is released into the hydrating cement paste. In this study, X-ray absorption measurements showed that considerable transport of water from saturated pumice...... the crucial factor to avoid self-desiccation shrinkage at early-age....

Transport of water and ions in partially water-saturated porous media. Part 2. Filtration effects

Science.gov (United States)

Revil, A.

2017-05-01

A new set of constitutive equations describing the transport of the ions and water through charged porous media and considering the effect of ion filtration is applied to the problem of reverse osmosis and diffusion of a salt. Starting with the constitutive equations derived in Paper 1, I first determine specific formula for the osmotic coefficient and effective diffusion coefficient of a binary symmetric 1:1 salt (such as KCl or NaCl) as a function of a dimensionless number Θ corresponding to the ratio between the cation exchange capacity (CEC) and the salinity. The modeling is first carried with the Donnan model used to describe the concentrations of the charge carriers in the pore water phase. Then a new model is developed in the thin double layer approximation to determine these concentrations. These models provide explicit relationships between the concentration of the ionic species in the pore space and those in a neutral reservoir in local equilibrium with the pore space and the CEC. The case of reverse osmosis and diffusion coefficient are analyzed in details for the case of saturated and partially saturated porous materials. Comparisons are done with experimental data from the literature obtained on bentonite. The model predicts correctly the influence of salinity (including membrane behavior at high salinities), porosity, cation type (K+ versus Na+), and water saturation on the osmotic coefficient. It also correctly predicts the dependence of the diffusion coefficient of the salt with the salinity.

Capillary pressure as a unique function of electric permittivity and water saturation

NARCIS (Netherlands)

Plug, W.J.; Slob, E.; Van Turnhout, J.; Bruining, J.

2007-01-01

The relation between capillary pressure (Pc) and interfacial area has been investigated by measuring Pc and the electric permittivity at 100 kHz simultaneously as function of the water saturation, (Sw). Drainage and imbibition experiments have been conducted for sand-distilled water-gas (CO2/N2)

Numerical evaluation of the water saturation in a high level radioactive waste disposal

International Nuclear Information System (INIS)

Benet, L.V.; Bouillet, Ch.; Tulita, C.; Wendling, J.

2010-01-01

Document available in extended abstract form only. This work is a contribution of the ANDRA's program of numerical simulations of the evolution in time of hydrogeological flows in a radioactive waste repository in deep clay formations. This study aims at evaluating the water contact areas with steel for corrosion modeling in a High-Level radioactive waste disposal, from the building to the total saturation, more than 100 000 years later [HSPA6b]. Energy release by radioactive spent fuel and thermal expansion of the interstitial water is taken into account in the models. Thermal transfers in the porous media and free convection in the gaps (Navier-Stokes equations) are computed with a linear Finite Element scheme. The mass transfers in the porous media are solved with a P0-P1 Mixed Finite Element method (Richard's equations during exploitation and two phases flow equations after the closure). All numerical simulations are performed with the Cast3M code (http://wwwcast3m. cea.fr/). During the exploitation, the H-L radioactive waste storage cell is not supposed to be hermetically closed. The pressure in the storage cell remains atmospheric and mass transfers towards the main gallery are possible. So a seepage boundary condition is used on excavation surface in order to provide evolution in time of saturation limit along the storage cell. For each cell of the boundary mesh: - No water flux is imposed in contact with unsaturated media. - Atmospheric pressure is imposed in contact with saturated media. A relative humidity of 50% is imposed for the atmosphere in the gallery. Vapour diffusive flux is implemented in Richard's equations with a suction pressure formula according to Kelvin law. Temperature impact on vapour flux is neglected. Vapour diffusive flux is significant in the concrete wall of gallery due to the ventilation. The free convection steady state in the gap is solved at different times of the thermal transient to evaluate location of

Experimental and numerical approaches of the hydro-mechanical behaviour of a quasi-saturated compacted clayey soil

Directory of Open Access Journals (Sweden)

Li Zhong-Sen

2016-01-01

Full Text Available The present research is funded by the French National Project « TerreDurable », which is dedicated to the study of soils in quasi-saturated conditions (close to saturation for the analysis of stability and settlement of earth structures such as embankment, dams. A global presentation of the drying-wetting test shows the volume change, air entry and soil-water characteristics of the soil at slurry and oven-dried conditions. Unsaturated undrained triaxial test was carried out in order to investigate the variation of pore-water pressure from quasi-saturated domain to saturation. The experimental results of the triaxial test are then modeled using a two-dimensional explicit finite difference program (Flac 2D. A constitutive law developed in the TerreDurable project allows better understanding the behaviour of quasi-saturated soils using the water retention curve of quasi-saturated domain proposed by Boutonnier (2007, 2010. A simple effective stress model is used (Cam Clay by taking into account both the suction and the compressibility of equivalent fluid (water + air. The results from numerical calculation and experimental measurements are compared.

Turbulence enhancement by ultrasonically induced gaseous cavitation in the CO2 saturated water

International Nuclear Information System (INIS)

Lee, Seung Youp; Choi, Young Don

2002-01-01

Recent primary concern for the design of high performance heat exchanger and highly integrated electronic equipment is to develop an active and creative technologies which enhance the heat transfer without obstructing the coolant flows. In this study, we found through the LDV measurement that the gaseous cavitation induced by ultrasonic vibration applied to the CO 2 saturated water in the square cross-sectioned straight duct flow enhances the turbulence much more than the case of non-ultrasonic or normal ultrasonic conditions without gaseous cavitation does. We also found that gaseous cavitation can enhance effectively the turbulent heat transfer between the heating surfaces and coolants by destructing the viscous sublayer

A Numerical Investigation on the Effect of Gas Pressure on the Water Saturation of Compacted Bentonite-Sand Samples

Directory of Open Access Journals (Sweden)

Jiang-Feng Liu

2017-01-01

Full Text Available In deep geological disposal for high-level radioactive waste, the generated gas can potentially affect the sealing ability of bentonite buffers. There is a competition between water and gas: the former provides sealing by swelling bentonite, and the latter attempts to desaturate the bentonite buffer. Thus, this study focused on numerically modelling the coupling effects of water and gas on the water saturation and sealing efficiency of compacted bentonite-sand samples. Different gas pressures were applied to the top surface of an upper sample, whereas the water pressure on the bottom side of the lower sample was maintained at 4 MPa. The results indicated that gas pressure did not significantly affect the saturation of the bentonite-sand sample until 2 MPa. At 2 MPa, the degree of water saturation of the upper sample was close to 1.0. As the gas pressure increased, this influence was more apparent. When the gas pressure was 6 MPa or higher, it was difficult for the upper sample to become fully saturated. Additionally, the lower sample was desaturated due to the high gas pressure. This indicated that gas pressure played an important role in the water saturation process and can affect the sealing efficiency of bentonite-based buffer materials.

A study of radon 222 permeation through plastic membranes. Application to a method of radon measurement in water and saturated soils

International Nuclear Information System (INIS)

Labed, V.

1991-04-01

In order to improve the BARASOL R device and to use it in water-saturated soils and in pressure constraint conditions, we have studied radon 222 permeation through plastic membranes. While the permeation process usually takes place between two media being in the same state, most often gaseous, the present study describes the transfer of radon 222 from the water to the air via a membrane. Polypropylene membranes have been tested with an experimental set-up by monitoring the evolution of radon concentrations in water and in air. The permeation coefficient and the activation energy were calculated in various conditions. With a second experimental set-up, we have tested the polyethylene membrane which has been adapted on the BARASOL. In these conditions, we have shown that it is possible to measure radon in water at concentrations around 10 3 Bq.m -3 [fr

PRO-QUEST: a rapid assessment method based on progressive saturation for quantifying exchange rates using saturation times in CEST.

Science.gov (United States)

Demetriou, Eleni; Tachrount, Mohamed; Zaiss, Moritz; Shmueli, Karin; Golay, Xavier

2018-03-05

To develop a new MRI technique to rapidly measure exchange rates in CEST MRI. A novel pulse sequence for measuring chemical exchange rates through a progressive saturation recovery process, called PRO-QUEST (progressive saturation for quantifying exchange rates using saturation times), has been developed. Using this method, the water magnetization is sampled under non-steady-state conditions, and off-resonance saturation is interleaved with the acquisition of images obtained through a Look-Locker type of acquisition. A complete theoretical framework has been set up, and simple equations to obtain the exchange rates have been derived. A reduction of scan time from 58 to 16 minutes has been obtained using PRO-QUEST versus the standard QUEST. Maps of both T 1 of water and B 1 can simply be obtained by repetition of the sequence without off-resonance saturation pulses. Simulations and calculated exchange rates from experimental data using amino acids such as glutamate, glutamine, taurine, and alanine were compared and found to be in good agreement. The PRO-QUEST sequence was also applied on healthy and infarcted rats after 24 hours, and revealed that imaging specificity to ischemic acidification during stroke was substantially increased relative to standard amide proton transfer-weighted imaging. Because of the reduced scan time and insensitivity to nonchemical exchange factors such as direct water saturation, PRO-QUEST can serve as an excellent alternative for researchers and clinicians interested to map pH changes in vivo. © 2018 International Society for Magnetic Resonance in Medicine.

Dynamic Mechanical Behavior of Dry and Water Saturated Igneous Rock with Acoustic Emission Monitoring

Directory of Open Access Journals (Sweden)

Jun Guo

2018-01-01

Full Text Available The uniaxial cyclic loading tests have been conducted to study the mechanical behavior of dry and water saturated igneous rock with acoustic emission (AE monitoring. The igneous rock samples are dried, naturally immersed, and boiled to get specimens with different water contents for the testing. The mineral compositions and the microstructures of the dry and water saturated igneous rock are also presented. The dry specimens present higher strength, fewer strains, and rapid increase of AE count subjected to the cyclic loading, which reflects the hard and brittle behavior and strong burst proneness of igneous rock. The water saturated specimens have lower peak strength, more accumulated strains, and increase of AE count during the cyclic loading. The damage of the igneous rocks with different water contents has been identified by the Felicity Ratio Analysis. The cyclic loading and unloading increase the dislocation between the mineral aggregates and the water-rock interactions further break the adhesion of the clay minerals, which jointly promote the inner damage of the igneous rock. The results suggest that the groundwater can reduce the burst proneness of the igneous rock but increase the potential support failure of the surrounding rock in igneous invading area. In addition, the results inspire the fact that the water injection method is feasible for softening the igneous rock and for preventing the dynamic disasters within the roadways and working faces located in the igneous intrusion area.

Thermohydraulic design of saturated temperature capsule for IASCC irradiation test

International Nuclear Information System (INIS)

Ide, Hiroshi; Matsui, Yoshinori; Itabashi, Yukio

2002-10-01

An advanced water chemistry controlled irradiation research device is being developed in JAERI, to perform irradiation tests for irradiation assisted stress corrosion cracking (IASCC) research concerned with aging of LWR. This device enables the irradiation tests under the water chemistry condition and the temperature, which simulate the conditions for BWR core internals. The advanced water chemistry controlled irradiation research device is composed of saturated temperature capsule inserted into the JMTR core and the water chemistry control unit installed in the reactor building. Regarding the saturated temperature capsule, the Thermohydraulic design of capsule structure was done, aimed at controlling the specimen's temperature, feeding water velocity on specimen's surface to the environment of BWR nearer. As the result of adopting the new capsule structure based on the design study, it was found out that feeding water velocity at the surface of specimen's is increased to about 10 times as much as before, and nuclear heat generated in the capsule components can be removed safely even in the abnormal event such as the case of loss of feeding water. (author)

Thermohydraulic design of saturated temperature capsule for IASCC irradiation test

Energy Technology Data Exchange (ETDEWEB)

Ide, Hiroshi; Matsui, Yoshinori; Itabashi, Yukio [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment] [and others

2002-10-01

An advanced water chemistry controlled irradiation research device is being developed in JAERI, to perform irradiation tests for irradiation assisted stress corrosion cracking (IASCC) research concerned with aging of LWR. This device enables the irradiation tests under the water chemistry condition and the temperature, which simulate the conditions for BWR core internals. The advanced water chemistry controlled irradiation research device is composed of saturated temperature capsule inserted into the JMTR core and the water chemistry control unit installed in the reactor building. Regarding the saturated temperature capsule, the Thermohydraulic design of capsule structure was done, aimed at controlling the specimen's temperature, feeding water velocity on specimen's surface to the environment of BWR nearer. As the result of adopting the new capsule structure based on the design study, it was found out that feeding water velocity at the surface of specimen's is increased to about 10 times as much as before, and nuclear heat generated in the capsule components can be removed safely even in the abnormal event such as the case of loss of feeding water. (author)

Soil aquifer treatment of artificial wastewater under saturated conditions

KAUST Repository

Essandoh, H. M K

2011-05-01

A 2000 mm long saturated laboratory soil column was used to simulate soil aquifer treatment under saturated conditions to assess the removal of chemical and biochemical oxygen demand (COD and BOD), dissolved organic carbon (DOC), nitrogen and phosphate, using high strength artificial wastewater. The removal rates were determined under a combination of constant hydraulic loading rates (HLR) and variable COD concentrations as well as variable HLR under a constant COD. Within the range of COD concentrations considered (42 mg L-1-135 mg L-1) it was found that at fixed hydraulic loading rate, a decrease in the influent concentrations of dissolved organic carbon (DOC), biochemical oxygen demand (BOD), total nitrogen and phosphate improved their removal efficiencies. At the high COD concentrations applied residence times influenced the redox conditions in the soil column. Long residence times were detrimental to the removal process for COD, BOD and DOC as anoxic processes and sulphate reduction played an important role as electron acceptors. It was found that total COD mass loading within the range of 911 mg d-1-1780 mg d-1 applied as low COD wastewater infiltrated coupled with short residence times would provide better effluent quality than the same mass applied as a COD with higher concentration at long residence times. The opposite was true for organic nitrogen where relatively high concentrations coupled with long residence time gave better removal efficiency. © 2011.

Using Neutron Radiography to Quantify Water Transport and the Degree of Saturation in Entrained Air Cement Based Mortar

Science.gov (United States)

Lucero, Catherine L.; Bentz, Dale P.; Hussey, Daniel S.; Jacobson, David L.; Weiss, W. Jason

Air entrainment is commonly added to concrete to help in reducing the potential for freeze thaw damage. It is hypothesized that the entrained air voids remain unsaturated or partially saturated long after the smaller pores fill with water. Small gel and capillary pores in the cement matrix fill quickly on exposure to water, but larger pores (entrapped and entrained air voids) require longer times or other methods to achieve saturation. As such, it is important to quantitatively determine the water content and degree of saturation in air entrained cementitious materials. In order to further investigate properties of cement-based mortar, a model based on Beer's Law has been developed to interpret neutron radiographs. This model is a powerful tool for analyzing images acquired from neutron radiography. A mortar with a known volume of aggregate, water to cement ratio and degree of hydration can be imaged and the degree of saturation can be estimated.

Contrast of dry and water-saturated arabidopsis seeds irradiated by MeV energy ions

International Nuclear Information System (INIS)

Mei Tao; Qin Huaili; Xue Jianming; Wang Yugang

2007-01-01

The dry and water-saturated seeds of Arabidopsis thaliana were irradiated by H + ions with 6.5 MeV in atmosphere. The ion fluence used in this experiment was in the range of 4 x 10 9 -1 x 10 14 ions/cm 2 . According to the structure of the seed and TRIM simulation, the ions with the energy of 6.5 MeV can penetrate the whole seed. The experiment shows that the fluence-response curves for the dry seeds and water-saturated seeds had distinct shoulders and reduced rapidly. The experimental results show that the water-imbibed seeds were more sensitive than the dry seeds and the reason is from free radicals reaction. A model has been constructed, and primely simulates the experiment data. (authors)

Saturated flow boiling heat transfer in water-heated vertical annulus

International Nuclear Information System (INIS)

Sun Licheng; Yan Changqi; Sun Zhonning

2005-01-01

This paper describes the saturated flow boiling heat transfer characteristics of water at 1 atm and low velocities in water-heated vertical annuli with equivalent diameters of 10 mm and 6 mm. Test section is consisted of two concentric circular tubes outer of which is made of quartz, so the whole test courses can be visualized. There are three main flow patterns of bubble flow, churn flow and churn-annular flow in the annuli, most important of which is churn flow. Flooding is the mechanism of churn flow and churn can enhance the heat transport between steam and water; Among the three factors of mass flux, inlet subcooling and annulus width, the last one has great effect on heat transport, moderately decreasing the annulus width can enhance the heat transfer; Combined annular flow model with theory of flooding and turbulent Prandtl Number, the numerical value of heat flux is given, the shape of test boiling curve and that of calculated by model is very alike, but there is large discrepancy between test data and calculated results, the most possible reason is that some parameters given by fluid flooding model are based on experimental data of common circular tubes, but not of annuli. Doing more research on flooding in annulus, particularly narrow annulus, is necessary for calculating the saturated boiling in annulus. (authors)

Use of azeotropic distillation for isotopic analysis of deuterium in soil water and saturate saline solution

International Nuclear Information System (INIS)

Santos, Antonio Vieira dos.

1995-05-01

The azeotropic distillation technique was adapted to extract soil water and saturate saline solution, which is similar to the sea water for the Isotopic Determination of Deuterium (D). A soil test was used to determine the precision and the nature of the methodology to extract soil water for stable isotopic analysis, using the azeotropic distillation and comparing with traditional methodology of heating under vacuum. This methodology has been very useful for several kinds of soil or saturate saline solution. The apparatus does not have a memory effect, and the chemical reagents do not affect the isotopic composition of soil water. (author). 43 refs., 10 figs., 12 tabs

Saturated and unsaturated stability analysis of slope subjected to rainfall infiltration

Directory of Open Access Journals (Sweden)

Gofar Nurly

2017-01-01

Full Text Available This paper presents results of saturated and unsaturated stability analysis of typical residual slopes subjected to rainfall infiltration corresponds to 50 years rainfall return period. The slope angles considered were 45° and 70°. The saturated stability analyses were carried out for original and critical ground water level commonly considered by practicing engineer. The analyses were conducted using limit equilibrium method. Unsaturated stability analyses used combination of coupled stress–pore-water pressure analysis to evaluate the effect of rainfall infiltration on the deformation and transient pore-water pressure on slope stability. Slope stability analyses were performed at some times during and after rainfall infiltration. Results show that the critical condition for slope made by sandy material was at the end of rainfall while for clayey material was at some specified times after the rainfall ceased. Unsaturated stability analysis on sandy soil gives higher factor of safety because the soil never reached saturation. Transient analysis using unsaturated soil concept could predict more critical condition of delayed failure of slopes made up of clayey soil.

Root morphology, hydraulic conductivity and plant water relations of high-yielding rice grown under aerobic conditions.

Science.gov (United States)

Kato, Yoichiro; Okami, Midori

2011-09-01

Increasing physical water scarcity is a major constraint for irrigated rice (Oryza sativa) production. 'Aerobic rice culture' aims to maximize yield per unit water input by growing plants in aerobic soil without flooding or puddling. The objective was to determine (a) the effect of water management on root morphology and hydraulic conductance, and (b) their roles in plant-water relationships and stomatal conductance in aerobic culture. Root system development, stomatal conductance (g(s)) and leaf water potential (Ψ(leaf)) were monitored in a high-yielding rice cultivar ('Takanari') under flooded and aerobic conditions at two soil moisture levels [nearly saturated (> -10 kPa) and mildly dry (> -30 kPa)] over 2 years. In an ancillary pot experiment, whole-plant hydraulic conductivity (soil-leaf hydraulic conductance; K(pa)) was measured under flooded and aerobic conditions. Adventitious root emergence and lateral root proliferation were restricted even under nearly saturated conditions, resulting in a 72-85 % reduction in total root length under aerobic culture conditions. Because of their reduced rooting size, plants grown under aerobic conditions tended to have lower K(pa) than plants grown under flooded conditions. Ψ(leaf) was always significantly lower in aerobic culture than in flooded culture, while g(s) was unchanged when the soil moisture was at around field capacity. g(s) was inevitably reduced when the soil water potential at 20-cm depth reached -20 kPa. Unstable performance of rice in water-saving cultivations is often associated with reduction in Ψ(leaf). Ψ(leaf) may reduce even if K(pa) is not significantly changed, but the lower Ψ(leaf) would certainly occur in case K(pa) reduces as a result of lower water-uptake capacity under aerobic conditions. Rice performance in aerobic culture might be improved through genetic manipulation that promotes lateral root branching and rhizogenesis as well as deep rooting.

Estimates of the hydrologic impact of drilling water on core samples taken from partially saturated densely welded tuff

International Nuclear Information System (INIS)

Buscheck, T.A.; Nitao, J.J.

1987-09-01

The purpose of this work is to determine the extent to which drill water might be expected to be imbibed by core samples taken from densely welded tuff. In a related experimental study conducted in G-Tunnel, drill water imbibition by the core samples was observed to be minimal. Calculations were carried out with the TOUGH code with the intent of corroborating the imbibition observations. Due to the absence of hydrologic data pertaining directly to G-Tunnel welded tuff, it was necessary to apply data from a similar formation. Because the moisture retention curve was not available for imbibition conditions, the drainage curve was applied to the model. The poor agreement between the observed and calculated imbibition data is attributed primarily to the inappropriateness of the drainage curve. Also significant is the value of absolute permeability (k) assumed in the model. Provided that the semi-log plot of the drainage and imbibition moisture retention curves are parallel within the saturation range of interest, a simple relationship exists between the moisture retention curve, k, and porosity (/phi/) which are assumed in the model and their actual values. If k and /phi/ are known, we define the hysteresis factor λ to be the ratio of the imbibition and drainage suction pressures for any saturation within the range of interest. If k and /phi/ are unknown, λ also accounts for the uncertainties in their values. Both the experimental and modeling studies show that drill water imbibition by the core has a minimal effect on its saturation state. 22 refs., 6 figs., 2 tabs

Effects of crude oil on water and tracer movement in the unsaturated and saturated zones.

Science.gov (United States)

Delin, Geoffrey N; Herkelrath, William N

2017-05-01

A tracer test was conducted to aid in the investigation of water movement and solute transport at a crude-oil spill site near Bemidji, Minnesota. Time of travel was measured using breakthrough curves for rhodamine WT and bromide tracers moving from the soil surface through oil-contaminated and oil-free unsaturated zones to the saturated zone. Results indicate that the rates of tracer movement were similar in the oil-free unsaturated and saturated zones compared to the oily zones. These results are somewhat surprising given the oil contamination in the unsaturated and saturated zones. Rhodamine tracer breakthrough in the unsaturated and saturated zones in general was delayed in comparison to bromide tracer breakthrough. Peak tracer concentrations for the lysimeters and wells in the oily zone were much greater than at the corresponding depths in the oil-free zone. Water and tracer movement in the oily zone was complicated by soil hydrophobicity and decreased oil saturations toward the periphery of the oil. Preferential flow resulted in reduced tracer interaction with the soil, adsorption, and dispersion and faster tracer movement in the oily zone than expected. Tracers were freely transported through the oily zone to the water table. Recharge calculations support the idea that the oil does not substantially affect recharge in the oily zone. This is an important result indicating that previous model-based assumptions of decreased recharge beneath the oil were incorrect. Results have important implications for modeling the fate and transport of dissolved contaminants at hydrocarbon spill sites. Published by Elsevier B.V.

Reactivity of dolomite in water-saturated supercritical carbon dioxide: Significance for carbon capture and storage and for enhanced oil and gas recovery

International Nuclear Information System (INIS)

Wang Xiuyu; Alvarado, Vladimir; Swoboda-Colberg, Norbert; Kaszuba, John P.

2013-01-01

Highlights: ► Dolomite reactivity with wet and dry supercritical CO 2 were evaluated. ► Dolomite does not react with dry CO 2 . ► H 2 O-saturated supercritical CO 2 dissolves dolomite and precipitates carbonate mineral. ► Temperature/reaction time control morphology and extent of carbonate mineralization. ► Reaction with wet CO 2 may impact trapping, caprock integrity, and CCS/EOR injectivity. - Abstract: Carbon dioxide injection in porous reservoirs is the basis for carbon capture and storage, enhanced oil and gas recovery. Injected carbon dioxide is stored at multiple scales in porous media, from the pore-level as a residual phase to large scales as macroscopic accumulations by the injection site, under the caprock and at reservoir internal capillary pressure barriers. These carbon dioxide saturation zones create regions across which the full spectrum of mutual CO 2 –H 2 O solubility may occur. Most studies assume that geochemical reaction is restricted to rocks and carbon dioxide-saturated formation waters, but this paradigm ignores injection of anhydrous carbon dioxide against brine and water-alternating-gas flooding for enhanced oil recovery. A series of laboratory experiments was performed to evaluate the reactivity of the common reservoir mineral dolomite with water-saturated supercritical carbon dioxide. Experiments were conducted at reservoir conditions (55 and 110 °C, 25 MPa) and elevated temperature (220 °C, 25 MPa) for approximately 96 and 164 h (4 and 7 days). Dolomite dissolves and new carbonate mineral precipitates by reaction with water-saturated supercritical carbon dioxide. Dolomite does not react with anhydrous supercritical carbon dioxide. Temperature and reaction time control the composition, morphology, and extent of formation of new carbonate minerals. Mineral dissolution and re-precipitation due to reaction with water-saturated carbon dioxide may affect the contact line between phases, the carbon dioxide contact angle, and the

[Determination of the redox potential of water saturated with hydrogen].

Science.gov (United States)

Piskarev, I M; Ushkanov, V A; Aristova, N A; Likhachev, P P; Myslivets, T C

2010-01-01

It has been shown that the redox potential of water saturated with hydrogen is -500--700 mV. The time of the establishment of the potential is 24 h. The potential somewhat increases with increasing volume of hydrogen introduced to a reservoir with water and practically does not depend on the presence of additions in water, provided these additions are not reduced by hydrogen. The pH value of water does not change after the addition of water. In a glass vessel with a metallic cover resting on the side, no decrease in potential during the 2.5-month storage was observed. In plastic bottles, the content of hydrogen decreased; on storage for more than two weeks, it disappeared almost completely, and as a result, the potential increased after storage for three to four weeks to a level near zero. In an open vessel, the potential remained negative for two days.

Busted Butte : final report on laboratory radionuclide migration experiments in non-welded tuff under unsaturated and saturated conditions

International Nuclear Information System (INIS)

Vandergraaf, T.T.; Drew, D.J.; Ticknor, K.V.; Hamon, C.J.

2004-01-01

Three blocks of non-welded tuff, one nominally one cubic foot (trial block) in volume and the other two, nominally one cubic meter (1 m 3 ) in volume, were excavated from the Busted Butte Test Facility on the Nevada Test Site in 1999 and transported to the Atomic Energy of Canada Limited Whiteshell Laboratories in Pinawa, Manitoba. The trial block and one of the 1-m 3 blocks were used for radionuclide migration experiments under unsaturated conditions; the remaining 1-m3 block was used for similar migration experiments under saturated conditions. After a vertical flow of synthetic transport solution was set up under unsaturated conditions, a suite of conservative and chemically reactive radionuclide tracers was injected at volumetric flow rates of 20 mL/hr in the trial block, and 10 mL/hr in two locations on the upper surface of the 1-m 3 block. These flow rates correspond to infiltration rates of about 120 cm/year and about 17 cm/year, respectively. The duration of the migration experiment in the trial block was 87 days, while the migration experiment in the 1-m3 block was performed for a period of 588 days. Results obtained from the migration experiment in the trial block showed that transport of 95m+99 Tc, injected as the pertechnetate (an)ion, was slightly faster than that of the transport solution, using tritiated water ( 3 H 2 0) as a flow indicator. Retardation of 237 Np was consistent with that predicted from results obtained in supporting static batch sorption studies. Post-migration analysis of the flow field in the trial block showed that the front of the 22 Na plume had migrated about half the distance through the block, and that 60 Co and 137 Cs had been retained near the inlet. This observation agrees qualitatively with that predicted from the results obtained in static batch sorption studies. In the larger-scale experiment, the transport behavior of Tc was also very similar to that of the transport solution. None of the other radionuclide tracers

Review: Water recovery from brines and salt-saturated solutions: operability and thermodynamic efficiency considerations for desalination technologies.

Science.gov (United States)

Vane, Leland M

2017-03-08

When water is recovered from a saline source, a brine concentrate stream is produced. Management of the brine stream can be problematic, particularly in inland regions. An alternative to brine disposal is recovery of water and possibly salts from the concentrate. This review provides an overview of desalination technologies and discusses the thermodynamic efficiencies and operational issues associated with the various technologies particularly with regard to high salinity streams. Due to the high osmotic pressures of the brine concentrates, reverse osmosis, the most common desalination technology, is impractical. Mechanical vapor compression which, like reverse osmosis, utilizes mechanical work to operate, is reported to have the highest thermodynamic efficiency of the desalination technologies for treatment of salt-saturated brines. Thermally-driven processes, such as flash evaporation and distillation, are technically able to process saturated salt solutions, but suffer from low thermodynamic efficiencies. This inefficiency could be offset if an inexpensive source of waste or renewable heat could be used. Overarching issues posed by high salinity solutions include corrosion and the formation of scales/precipitates. These issues limit the materials, conditions, and unit operation designs that can be used.

Evaluation of water transfer from saturated lightweight aggregate to cement paste matrix by neutron radiography

International Nuclear Information System (INIS)

Maruyama, I.; Kanematsu, M.; Noguchi, T.; Iikura, H.; Teramoto, A.; Hayano, H.

2009-01-01

In high-strength concrete with low water-cement ratio, self-desiccation occurs due to cement hydration and causes shrinkage and an increased risk of cracking. While high-strength concrete has a denser matrix than normal-strength concrete, resulting in lower permeability, early-age cracks would cancel out this advantage. For the mitigation of this self-desiccation and resultant shrinkage, water-saturated porous aggregate, such as artificial lightweight aggregate, may be used in high-strength concrete. In this contribution, for the purpose of clarification of the volume change of high-strength concrete containing water-saturated lightweight aggregate, water transfer from the lightweight aggregate to cement paste matrix is visualized by neutron radiography. As a result, it is clear that water was supplied to the cement paste matrix in the range 3-8 mm from the surface of the aggregate, and the osmotic forces may yield water transfer around lightweight aggregate in a few hours after mixing.

Effect of percolation rate on water-travel time in deep, partially saturated zones

International Nuclear Information System (INIS)

Peters, R.R.; Gauthier, J.H.; Dudley, A.L.

1986-02-01

The Nevada Nuclear Waste Storage Investigations (NNWSI) project is investigating Yucca Mountain, Nye county, Nevada, as a prospective site for a radioactive-waste repository. The Yucca Mountain site is unique among those currently being investigated by the US Department of Energy (DOE) in that the prospective repository location is in the unsaturated zone, approximately 300 m above the water table. The rock units at Yucca Mountain can be grouped into three types: (1) vitric tuffs with high matrix conductivity and few fractures; (2) zeolitized tuffs with low matrix conductivity and few fractures; and (3) densely welded tuffs with low matrix conductivities and many fractures. The prospective repository zone is in densely welded tuff; the units between it and the water table are of types 1 and 2. Current percolation rates through Yucca Mountain, and those that are currently postulated under future climatic conditions, are thought to be of the order of the saturated matrix conductivity of some of the units. Although it is probable that there is now little or no water movement in fracture, it is necessary to investigate the potential for fracture flow, especially that which could be initiated under future climatic conditions. Significant fracture flow, if present, could reduce the water travel time between the repository and the water table. A composite-porosity, continuum model was developed to model flow in a fractured, porous medium. Simulations using data from the Yucca Mountain site and this model in the one-dimensional code TOSPAC indicate that current estimates of the percolation rate result in water movement confined to the matrix and that the water-travel time from the repository to the water table is on the order of hundreds of thousands of years. this result is sensitive to the percolation rate; an increase in percolation rate of a factor of 10 many initiate water movement in the fractures, reducing the travel time significantly

Experimental and numerical study on frost heave of saturated rock under uniform freezing conditions

Science.gov (United States)

Lv, Zhitao; Xia, Caichu; Li, Qiang

2018-04-01

A series of freezing experiments are conducted on saturated sandstone and mortar specimens to investigate the frost heave of saturated rock under uniform freezing conditions. The experimental results show that the frost heave of saturated rock is isotropic under uniform freezing conditions. During the freezing process, three stages are observed in the curves of variation of total frost heaving strain versus time: the thermal contraction stage, the frost heaving stage and the steady stage. Moreover, the amount of final stable frost heave first increases and then decreases with decrease in freezing temperature, and the maximum final stable frost heave occurs at different freezing temperature in saturated sandstone and mortar. Furthermore, a coupled thermal-mechanical (TM) model of frost heave of saturated rock is proposed in which a constraint coefficient \\zeta is used to consider the susceptibility of the internal rock grain structure to the expansion of pore ice. Then, numerical simulations are implemented with COMSOL to solve the governing equations of the TM model. Comparisons of the numerical results with the experimental results are performed to demonstrate the reliability of the model. The influences of elastic modulus and porosity on frost heave are also investigated, and the results show that the total frost heaving strain decreases non-linearly with increasing elastic modulus, and the decrease is significant when the elastic modulus is less than 3000 MPa, or approximately five times the elastic modulus of ice. In addition, the total frost heaving strain increases linearly with increasing porosity. Finally, an empirical equation between total frost heaving strain and freezing temperature is proposed and the equation well describes the variation of total frost heaving strain with freezing temperature.

Studies of non-isothermal flow in saturated and partially saturated porous media

International Nuclear Information System (INIS)

Ho, C.K.; Maki, K.S.; Glass, R.J.

1993-01-01

Physical and numerical experiments have been performed to investigate the behavior of nonisothermal flow in two-dimensional saturated and partially saturated porous media. The physical experiments were performed to identify non-isothermal flow fields and temperature distributions in fully saturated, half-saturated, and residually saturated two-dimensional porous media with bottom heating and top cooling. Two counter-rotating liquid-phase convective cells were observed to develop in the saturated regions of all three cases. Gas-phase convection was also evidenced in the unsaturated regions of the partially saturated experiments. TOUGH2 numerical simulations of the saturated case were found to be strongly dependent on the assumed boundary conditions of the physical system. Models including heat losses through the boundaries of the test cell produced temperature and flow fields that were in better agreement with the observed temperature and flow fields than models that assumed insulated boundary conditions. A sensitivity analysis also showed that a reduction of the bulk permeability of the porous media in the numerical simulations depressed the effects of convection, flattening the temperature profiles across the test cell

Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model

International Nuclear Information System (INIS)

K. Rehfeldt

2004-01-01

This report is an updated analysis of water-level data performed to provide the ''Saturated Zone Site-Scale Flow Model'' (BSC 2004 [DIRS 170037]) (referred to as the saturated zone (SZ) site-scale flow model or site-scale SZ flow model in this report) with the configuration of the potentiometric surface, target water-level data, and hydraulic gradients for calibration of groundwater flow models. This report also contains an expanded discussion of uncertainty in the potentiometric-surface map. The analysis of the potentiometric data presented in Revision 00 of this report (USGS 2001 [DIRS 154625]) provides the configuration of the potentiometric surface, target heads, and hydraulic gradients for the calibration of the SZ site-scale flow model (BSC 2004 [DIRS 170037]). Revision 01 of this report (USGS 2004 [DIRS 168473]) used updated water-level data for selected wells through the year 2000 as the basis for estimating water-level altitudes and the potentiometric surface in the SZ site-scale flow and transport model domain based on an alternative interpretation of perched water conditions. That revision developed computer files containing: Water-level data within the model area (DTN: GS010908312332.002); A table of known vertical head differences (DTN: GS010908312332.003); and A potentiometric-surface map (DTN: GS010608312332.001) using an alternative concept from that presented by USGS (2001 [DIRS 154625]) for the area north of Yucca Mountain. The updated water-level data presented in USGS (2004 [DIRS 168473]) include data obtained from the Nye County Early Warning Drilling Program (EWDP) Phases I and II and data from Borehole USW WT-24. This document is based on Revision 01 (USGS 2004 [DIRS 168473]) and expands the discussion of uncertainty in the potentiometric-surface map. This uncertainty assessment includes an analysis of the impact of more recent water-level data and the impact of adding data from the EWDP Phases III and IV wells. In addition to being utilized

Alteration of borosilicate glass under water saturated condition

International Nuclear Information System (INIS)

Tsukimura, K.; Matsuhisa, Y.; Kanai, Y.; Hirai, H.

1991-01-01

In the long term of the high-level nuclear waste disposal, the dissolving rates of radionuclides from the waste will be controlled by crystalline phases secondarily formed in the borosilicate glass by reaction with ground water. We have determined the crystalline phases formed from borosilicate glass in a hydrothermal experiment. Borosilicate glass powder (50 mg, Si 40 B 20 Al 4 Li 12 Na 14 K 3 Ca 2 Fe 5 O 140 ) and 200 ml of water were reacted at 300degC and 300 bars for 2 weeks with a cold-seal type hydrothermal high pressure apparatus. After the reaction the liquid phase was analyzed with atomic absorption spectroscopy and the solid phases with x-ray powder diffraction and analytical electron microscopy. The liquid phase contains 58 % of Na, 14 % of Li and 11 % of K but less than 1 % of Ca and Fe. The solid phases were found to be zeolite and smectite. The zeolite is isostructural with analcime Na 2 Al 2 (SiO 3 ) 4 · 2H 2 O or wairakite CaAl 2 (SiO 3 ) 4 · 2H 2 O and contains Ca and Si as major constituents but does not contain Al. Although no direct analytical evidence is available, logical induction of the experimental results indicates that the chemical composition of the zeolite is CaB 2 (SiO 3 ) 4 . The remaining x-ray powder diffraction peaks are same as those of smectite Na 06.7 (Al 3.33 Mg 0.67 )Si 8 O 20 (OH) 4 . However, since our starting material was free of Mg, and Na was not detected by AEM, the smectite may contain Fe instead of Mg, and Li instead of Na. (author)

On the extension of multi-phase models to sub-residual saturations

International Nuclear Information System (INIS)

Lingineni, S.; Chen, Y.T.; Boehm, R.F.

1995-01-01

This paper focuses on the limitations of applying multi-phase flow and transport models to simulate the hydrothermal processes occurring when the liquid saturation falls below residual levels. A typical scenario of a heat-generating high-level waste package emplaced in a backfilled drift of a waste repository is presented. The hydrothermal conditions in the vicinity of the waste package as well as in the far-field are determined using multi-phase, non-isothermal codes such as TOUGH2 and FEHM. As the waste package temperature increases, heat-pipe effects are created and water is driven away from the package into colder regions where it condenses. The variations in the liquid saturations close to the waste package are determined using these models with extended capillary pressure-saturations relationships to sub-residual regime. The predictions indicate even at elevated temperatures, waste package surroundings are not completely dry. However, if transport based modeling is used to represent liquid saturation variations in the sub-residual regime, then complete dry conditions are predicted within the backfill for extended periods of time. The relative humidity conditions near the waste package are also found to be sensitive to the representation of capillary pressure-saturation relationship used for sub-residual regime. An experimental investigation is carried out to study the variations in liquid saturations and relative humidity conditions in sub-residual regimes. Experimental results indicated that extended multi-phase models without interphase transport can not predict dry-out conditions and the simulations underpredict the humidity conditions near the waste package

Notes on HP1 a software package for simulating variably-saturated water flow, heat transport, solute transport, and biogeochemistry in porous media. HP1 Version 2.2

Energy Technology Data Exchange (ETDEWEB)

Jacques, D.; Simunek, J.

2010-01-15

HP1 is a comprehensive modeling tool in terms of processes and reactions for simulating reactive transport and biogeochemical processes in variably-saturated porous media. HP1 results from coupling the water and solute transport model HYDRUS-1D (Simunek et al., 2009a) and PHREEQC-2 (Parkhurst and Appelo, 1999). This note provides an overview of how to set up and execute a HP1 project using version 2.2.002 of HP1 and version 4.13 of the graphical user interface (GUI) of HYDRUS-1D. A large part of this note are step-by-step instructions for selected examples involving mineral dissolution and precipitation, cation exchange, surface complexation and kinetic degradation networks. The implementation of variably-saturated flow conditions, changing boundary conditions, a layered soil profile or immobile water is also illustrated.

Notes on HP1 a software package for simulating variably-saturated water flow, heat transport, solute transport, and biogeochemistry in porous media. HP1 Version 2.2

International Nuclear Information System (INIS)

Jacques, D.; Simunek, J.

2010-01-01

HP1 is a comprehensive modeling tool in terms of processes and reactions for simulating reactive transport and biogeochemical processes in variably-saturated porous media. HP1 results from coupling the water and solute transport model HYDRUS-1D (Simunek et al., 2009a) and PHREEQC-2 (Parkhurst and Appelo, 1999). This note provides an overview of how to set up and execute a HP1 project using version 2.2.002 of HP1 and version 4.13 of the graphical user interface (GUI) of HYDRUS-1D. A large part of this note are step-by-step instructions for selected examples involving mineral dissolution and precipitation, cation exchange, surface complexation and kinetic degradation networks. The implementation of variably-saturated flow conditions, changing boundary conditions, a layered soil profile or immobile water is also illustrated.

Effect of boundary conditions on measured water retention behavior within soils

Science.gov (United States)

Galindo-torres, S.; Scheuermann, A.; Pedroso, D.; Li, L.

2013-12-01

The Soil Water Characteristic Curve (SWCC) is a practical representation of the behavior of soil water by relating the suction (difference between the air and water pressures to the moisture content (water saturation). The SWCC is characterized by a hysteresis loop, which is thought to be unique in that any drainage-imbibition cycle lies within a main hysteresis loop limited by two different curves for drainage and imbibition. This 'uniqueness' is the main argument for considering the SWCC as a material-intrinsic feature that characterizes the pore structure and its interaction with fluids. Models have been developed with the SWCC as input data to describe the evolution of the water saturation and the suction within soils. One example of these models is the widely used Richard's equation [1]. In this work we present a series of numerical simulations to evaluate the 'unique' nature of the SWCC. The simulations involves the use of the Lattice Boltzmann Method (LBM) [2] within a regular soil, modelling the flow behavior of two immiscible fluids: wetting and non-wetting. The soil is packed within a cubic domain to resemble the experimental setups that are commonly used for measuring the SWCC[3]. The boundary conditions ensure that the non-wetting phase enters through one cubic face and the wetting phase enters trough the opposite phase, with no flow boundary conditions in the remaining 4 cubic faces. The SWCC known features are inspected including the presence of the common limit curves for different cycles involving varying limits for the suction. For this stage of simulations, the SWCC is indeed unique. Later, different boundary conditions are applied with the two fluids each injected from 3 opposing faces into the porous medium. The effect of this boundary condition change is a net flow direction, which is different from that in the previous case. A striking result is observed when both SWCC are compared and found to be noticeable different. Further analysis is

Oil/water displacement in microfluidic packed beds under weakly water-wetting conditions: competition between precursor film flow and piston-like displacement

Science.gov (United States)

Tanino, Yukie; Zacarias-Hernandez, Xanat; Christensen, Magali

2018-02-01

Optical microscopy was used to measure depth-averaged oil distribution in a quasi-monolayer of crushed marble packed in a microfluidic channel as it was displaced by water. By calibrating the transmitted light intensity to oil thickness, we account for depth variation in the fluid distribution. Experiments reveal that oil saturation at water breakthrough decreases with increasing Darcy velocity, U_{ {w}}, between capillary numbers {Ca} = μ _{ {w}} U_{ {w}}/σ = 9× 10^{-7} and 9× 10^{-6}, where μ _{ {w}} is the dynamic viscosity of water and σ is the oil/water interfacial tension, under the conditions considered presently. In contrast, end-point (long-time) remaining oil saturation depends only weakly on U_{ {w}}. This transient dependence on velocity is attributed to the competition between precursor film flow, which controls early time invasion dynamics but is inefficient at displacing oil, and piston-like displacement, which controls ultimate oil recovery. These results demonstrate that microfluidic experiments using translucent grains and fluids are a convenient tool for quantitative investigation of sub-resolution liquid/liquid displacement in porous media.

Analysis of grain growth process in melt spun Fe-B alloys under the initial saturated grain boundary segregation condition

International Nuclear Information System (INIS)

Chen, Z.; Liu, F.; Yang, X.Q.; Fan, Y.; Shen, C.J.

2012-01-01

Highlights: → We compared pure kinetic, pure thermodynamic and extended thermo-kinetic models. → An initial saturated GB segregation condition of nanoscale Fe-B alloys was determined. → The controlled-mechanism was proposed using two characteristic times (t 1 and t 2 ). - Abstract: A grain growth process in the melt spun low-solid-solubility Fe-B alloys was analyzed under the initial saturated grain boundary (GB) segregation condition. Applying melt spinning technique, single-phase supersaturated nanograins were prepared. Grain growth behavior of the single-phase supersaturated nanograins was investigated by performing isothermal annealing at 700 deg. C. Combined with the effect of GB segregation on the initial GB excess amount, the thermo-kinetic model [Chen et al., Acta Mater. 57 (2009) 1466] was extended to describe the initial GB segregation condition of nanoscale Fe-B alloys. In comparison of pure kinetic model, pure thermodynamic model and the extended thermo-kinetic model, an initial saturated GB segregation condition was determined. The controlled-mechanism of grain growth under initial saturated GB segregation condition was proposed using two characteristic annealing times (t 1 and t 2 ), which included a mainly kinetic-controlled process (t ≤ t 1 ), a transition from kinetic-mechanism to thermodynamic-mechanism (t 1 2 ) and pure thermodynamic-controlled process (t ≥ t 2 ).

Dissolution of spherical cap CO2 bubbles attached to flat surfaces in air-saturated water

Science.gov (United States)

Peñas, Pablo; Parrales, Miguel A.; Rodriguez-Rodriguez, Javier

2014-11-01

Bubbles attached to flat surfaces immersed in quiescent liquid environments often display a spherical cap (SC) shape. Their dissolution is a phenomenon commonly observed experimentally. Modelling these bubbles as fully spherical may lead to an inaccurate estimate of the bubble dissolution rate. We develop a theoretical model for the diffusion-driven dissolution or growth of such multi-component SC gas bubbles under constant pressure and temperature conditions. Provided the contact angle of the bubble with the surface is large, the concentration gradients in the liquid may be approximated as spherically symmetric. The area available for mass transfer depends on the instantaneous bubble contact angle, whose dynamics is computed from the adhesion hysteresis model [Hong et al., Langmuir, vol. 27, 6890-6896 (2011)]. Numerical simulations and experimental measurements on the dissolution of SC CO2 bubbles immersed in air-saturated water support the validity of our model. We verify that contact line pinning slows down the dissolution rate, and the fact that any bubble immersed in a saturated gas-liquid solution eventually attains a final equilibrium size. Funded by the Spanish Ministry of Economy and Competitiveness through Grant DPI2011-28356-C03-0.

Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model

Energy Technology Data Exchange (ETDEWEB)

K. Rehfeldt

2004-10-08

This report is an updated analysis of water-level data performed to provide the ''Saturated Zone Site-Scale Flow Model'' (BSC 2004 [DIRS 170037]) (referred to as the saturated zone (SZ) site-scale flow model or site-scale SZ flow model in this report) with the configuration of the potentiometric surface, target water-level data, and hydraulic gradients for calibration of groundwater flow models. This report also contains an expanded discussion of uncertainty in the potentiometric-surface map. The analysis of the potentiometric data presented in Revision 00 of this report (USGS 2001 [DIRS 154625]) provides the configuration of the potentiometric surface, target heads, and hydraulic gradients for the calibration of the SZ site-scale flow model (BSC 2004 [DIRS 170037]). Revision 01 of this report (USGS 2004 [DIRS 168473]) used updated water-level data for selected wells through the year 2000 as the basis for estimating water-level altitudes and the potentiometric surface in the SZ site-scale flow and transport model domain based on an alternative interpretation of perched water conditions. That revision developed computer files containing: Water-level data within the model area (DTN: GS010908312332.002); A table of known vertical head differences (DTN: GS010908312332.003); and A potentiometric-surface map (DTN: GS010608312332.001) using an alternative concept from that presented by USGS (2001 [DIRS 154625]) for the area north of Yucca Mountain. The updated water-level data presented in USGS (2004 [DIRS 168473]) include data obtained from the Nye County Early Warning Drilling Program (EWDP) Phases I and II and data from Borehole USW WT-24. This document is based on Revision 01 (USGS 2004 [DIRS 168473]) and expands the discussion of uncertainty in the potentiometric-surface map. This uncertainty assessment includes an analysis of the impact of more recent water-level data and the impact of adding data from the EWDP Phases III and IV wells. In

User manual of the multicompenent variably - saturated flow and transport model HP1

International Nuclear Information System (INIS)

Jacques, D.; Simunek, J.

2005-06-01

This report describes a new comprehensive simulation tool HP1 (HYDRUS1D-PHREEQC) that was obtained by coupling the HYDRUS-1D one-dimensional variably-saturated water flow and solute transport model with the PHREEQC geochemical code. The HP1 code incorporates modules simulating (1) transient water flow in variably-saturated media, (2) transport of multiple components, and (3) mixed equilibrium/kinetic geochemical reactions. The program numerically solves the Richards equation for variably-saturated water flow and advection-dispersion type equations for heat and solute transport. The flow equation incorporates a sink term to account for water uptake by plant roots. The heat transport equation considers transport due to conduction and convection with flowing water. The solute transport equations consider advective-dispersive transport in the liquid phase. The program can simulate a broad range of low-temperature biogeochemical reactions in water, soil and ground water systems including interactions with minerals, gases, exchangers, and sorption surfaces, based on thermodynamic equilibrium, kinetics, or mixed equilibrium-kinetic reactions. The program may be used to analyze water and solute movement in unsaturated, partially saturated, or fully saturated porous media. The flow region may be composed of nonuniform soils or sediments. Flow and transport can occur in the vertical, horizontal, or a generally inclined direction. The water flow part of the model can deal with prescribed head and flux boundaries, boundaries controlled by atmospheric conditions, as well as free drainage boundary conditions. The governing flow and transport equations were solved numerically using Galerkin-type linear finite element schemes. To test the accuracy of the coupling procedures implemented in HP1, simulation results were compared with (i) HYDRUS-1D for transport problems of multiple components subject to sequential first-order decay, (ii) PHREEQC for steady-state flow conditions, and

Experimental burial inhibits methanogenesis and anaerobic decomposition in water-saturated peats.

Science.gov (United States)

Blodau, Christian; Siems, Melanie; Beer, Julia

2011-12-01

A mechanistic understanding of carbon (C) sequestration and methane (CH(4)) production is of great interest due to the importance of these processes for the global C budget. Here we demonstrate experimentally, by means of column experiments, that burial of water saturated, anoxic bog peat leads to inactivation of anaerobic respiration and methanogenesis. This effect can be related to the slowness of diffusive transport of solutes and evolving energetic constraints on anaerobic respiration. Burial lowered decomposition constants in homogenized peat sand mixtures from about 10(-5) to 10(-7) yr(-1), which is considerably slower than previously assumed, and methanogenesis slowed down in a similar manner. The latter effect could be related to acetoclastic methanogenesis approaching a minimum energy quantum of -25 kJ mol(-1) (CH(4)). Given the robustness of hydraulic properties that locate the oxic-anoxic boundary near the peatland surface and constrain solute transport deeper into the peat, this effect has likely been critical for building the peatland C store and will continue supporting long-term C sequestration in northern peatlands even under moderately changing climatic conditions.

Shell condition and survival of Puget Sound pteropods are impaired by ocean acidification conditions.

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D Shallin Busch

Full Text Available We tested whether the thecosome pteropod Limacina helicina from Puget Sound, an urbanized estuary in the northwest continental US, experiences shell dissolution and altered mortality rates when exposed to the high CO2, low aragonite saturation state (Ωa conditions that occur in Puget Sound and the northeast Pacific Ocean. Five, week-long experiments were conducted in which we incubated pteropods collected from Puget Sound in four carbon chemistry conditions: current summer surface (∼460-500 µatm CO2, Ωa≈1.59, current deep water or surface conditions during upwelling (∼760 and ∼1600-1700 µatm CO2, Ωa≈1.17 and 0.56, and future deep water or surface conditions during upwelling (∼2800-3400 µatm CO2, Ωa≈0.28. We measured shell condition using a scoring regime of five shell characteristics that capture different aspects of shell dissolution. We characterized carbon chemistry conditions in statistical analyses with Ωa, and conducted analyses considering Ωa both as a continuous dataset and as discrete treatments. Shell dissolution increased linearly as aragonite saturation state decreased. Discrete treatment comparisons indicate that shell dissolution was greater in undersaturated treatments compared to oversaturated treatments. Survival increased linearly with aragonite saturation state, though discrete treatment comparisons indicated that survival was similar in all but the lowest saturation state treatment. These results indicate that, under starvation conditions, pteropod survival may not be greatly affected by current and expected near-future aragonite saturation state in the NE Pacific, but shell dissolution may. Given that subsurface waters in Puget Sound's main basin are undersaturated with respect to aragonite in the winter and can be undersaturated in the summer, the condition and persistence of the species in this estuary warrants further study.

Shell condition and survival of Puget Sound pteropods are impaired by ocean acidification conditions.

Science.gov (United States)

Busch, D Shallin; Maher, Michael; Thibodeau, Patricia; McElhany, Paul

2014-01-01

We tested whether the thecosome pteropod Limacina helicina from Puget Sound, an urbanized estuary in the northwest continental US, experiences shell dissolution and altered mortality rates when exposed to the high CO2, low aragonite saturation state (Ωa) conditions that occur in Puget Sound and the northeast Pacific Ocean. Five, week-long experiments were conducted in which we incubated pteropods collected from Puget Sound in four carbon chemistry conditions: current summer surface (∼460-500 µatm CO2, Ωa≈1.59), current deep water or surface conditions during upwelling (∼760 and ∼1600-1700 µatm CO2, Ωa≈1.17 and 0.56), and future deep water or surface conditions during upwelling (∼2800-3400 µatm CO2, Ωa≈0.28). We measured shell condition using a scoring regime of five shell characteristics that capture different aspects of shell dissolution. We characterized carbon chemistry conditions in statistical analyses with Ωa, and conducted analyses considering Ωa both as a continuous dataset and as discrete treatments. Shell dissolution increased linearly as aragonite saturation state decreased. Discrete treatment comparisons indicate that shell dissolution was greater in undersaturated treatments compared to oversaturated treatments. Survival increased linearly with aragonite saturation state, though discrete treatment comparisons indicated that survival was similar in all but the lowest saturation state treatment. These results indicate that, under starvation conditions, pteropod survival may not be greatly affected by current and expected near-future aragonite saturation state in the NE Pacific, but shell dissolution may. Given that subsurface waters in Puget Sound's main basin are undersaturated with respect to aragonite in the winter and can be undersaturated in the summer, the condition and persistence of the species in this estuary warrants further study.

Mechanics of non-saturated soils

International Nuclear Information System (INIS)

Coussy, O.; Fleureau, J.M.

2002-01-01

This book presents the different ways to approach the mechanics of non saturated soils, from the physico-chemical aspect to the mechanical aspect, from the experiment to the theoretical modeling, from the laboratory to the workmanship, and from the microscopic scale to the macroscopic one. Content: water and its representation; experimental bases of the behaviour of non-saturated soils; transfer laws in non-saturated environment; energy approach of the behaviour of non-saturated soils; homogenization for the non-saturated soils; plasticity and hysteresis; dams and backfilling; elaborated barriers. (J.S.)

Effects of Contrast Agent and Outer Volume Saturation Bands on Water Suppression and Shimming of Hepatic Single-Volume Proton MR Spectroscopy at 3.0T

Directory of Open Access Journals (Sweden)

Li Xu

2012-01-01

Full Text Available Purpose. To determine whether administration of gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA and whether placement of the outer volume saturation bands significantly affect shimming and water suppression on hepatic MR spectroscopic prescanning. Method. Region of interest (ROI of 2 cm × 2 cm × 2 cm was carefully positioned in the region of the middle portion of the right hepatic lobe. 32 patients were examined before and after administration of Gd-DTPA with and without outer-volume saturation bands. Linewidths (Full-Width Half-Maximum (FWHM and water suppression were obtained. A paired t-test for comparison of means was used. Results. (1 The group with the outer volume saturation bands demonstrated slightly better water suppression effect than the group without outer volume saturation bands before administration. (2 The group with the outer volume saturation bands demonstrated better water suppression effect than the group without outer volume saturation bands after administration. (3 Both shimming and water suppression effectswere decreased on enhanced MR spectroscopic prescanning (all P<0.05. Conclusions. Placement of the outer volume saturation bands is helpful to improve water suppression both before and after contrast agent administration. Gd-DTPA exerts a slightly adverse effect (a statistically significant but clinically unimportant on magnetic resonance spectroscopic prescanning at 3T.

Prediction of the saturated hydraulic conductivity from Brooks and Corey’s water retention parameters

NARCIS (Netherlands)

Nasta, P.; Vrugt, J.A.; Romano, N.

2013-01-01

Prediction of flow through variably saturated porous media requires accurate knowledge of the soil hydraulic properties, namely the water retention function (WRF) and the hydraulic conductivity function (HCF). Unfortunately, direct measurement of the HCF is time consuming and expensive. In this

Method of coupling 1-D unsaturated flow with 3-D saturated flow on large scale

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Yan Zhu

2011-12-01

Full Text Available A coupled unsaturated-saturated water flow numerical model was developed. The water flow in the unsaturated zone is considered the one-dimensional vertical flow, which changes in the horizontal direction according to the groundwater table and the atmospheric boundary conditions. The groundwater flow is treated as the three-dimensional water flow. The recharge flux to groundwater from soil water is considered the bottom flux for the numerical simulation in the unsaturated zone, and the upper flux for the groundwater simulation. It connects and unites the two separated water flow systems. The soil water equation is solved based on the assumed groundwater table and the subsequent predicted recharge flux. Then, the groundwater equation is solved with the predicted recharge flux as the upper boundary condition. Iteration continues until the discrepancy between the assumed and calculated groundwater nodal heads have a certain accuracy. Illustrative examples with different water flow scenarios regarding the Dirichlet boundary condition, the Neumann boundary condition, the atmospheric boundary condition, and the source or sink term were calculated by the coupled model. The results are compared with those of other models, including Hydrus-1D, SWMS-2D, and FEFLOW, which demonstrate that the coupled model is effective and accurate and can significantly reduce the computational time for the large number of nodes in saturated-unsaturated water flow simulation.

The Dependence of Water Permeability in Quartz Sand on Gas Hydrate Saturation in the Pore Space

Science.gov (United States)

Kossel, E.; Deusner, C.; Bigalke, N.; Haeckel, M.

2018-02-01

Transport of fluids in gas hydrate bearing sediments is largely defined by the reduction of the permeability due to gas hydrate crystals in the pore space. Although the exact knowledge of the permeability behavior as a function of gas hydrate saturation is of crucial importance, state-of-the-art simulation codes for gas production scenarios use theoretically derived permeability equations that are hardly backed by experimental data. The reason for the insufficient validation of the model equations is the difficulty to create gas hydrate bearing sediments that have undergone formation mechanisms equivalent to the natural process and that have well-defined gas hydrate saturations. We formed methane hydrates in quartz sand from a methane-saturated aqueous solution and used magnetic resonance imaging to obtain time-resolved, three-dimensional maps of the gas hydrate saturation distribution. These maps were fed into 3-D finite element method simulations of the water flow. In our simulations, we tested the five most well-known permeability equations. All of the suitable permeability equations include the term (1-SH)n, where SH is the gas hydrate saturation and n is a parameter that needs to be constrained. The most basic equation describing the permeability behavior of water flow through gas hydrate bearing sand is k = k0 (1-SH)n. In our experiments, n was determined to be 11.4 (±0.3). Results from this study can be directly applied to bulk flow analysis under the assumption of homogeneous gas hydrate saturation and can be further used to derive effective permeability models for heterogeneous gas hydrate distributions at different scales.

Classification of the Group Invariant Solutions for Contaminant Transport in Saturated Soils under Radial Uniform Water Flows

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M. M. Potsane

2014-01-01

Full Text Available The transport of chemicals through soils to the groundwater or precipitation at the soils surfaces leads to degradation of these resources. Serious consequences may be suffered in the long run. In this paper, we consider macroscopic deterministic models describing contaminant transport in saturated soils under uniform radial water flow backgrounds. The arising convection-dispersion equation given in terms of the stream functions is analyzed using classical Lie point symmetries. A number of exotic Lie point symmetries are admitted. Group invariant solutions are classified according to the elements of the one-dimensional optimal systems. We analyzed the group invariant solutions which satisfy the physical boundary conditions.

Differential equations governing slip-induced pore-pressure fluctuations in a water-saturated granular medium

Science.gov (United States)

Iverson, R.M.

1993-01-01

Macroscopic frictional slip in water-saturated granular media occurs commonly during landsliding, surface faulting, and intense bedload transport. A mathematical model of dynamic pore-pressure fluctuations that accompany and influence such sliding is derived here by both inductive and deductive methods. The inductive derivation shows how the governing differential equations represent the physics of the steadily sliding array of cylindrical fiberglass rods investigated experimentally by Iverson and LaHusen (1989). The deductive derivation shows how the same equations result from a novel application of Biot's (1956) dynamic mixture theory to macroscopic deformation. The model consists of two linear differential equations and five initial and boundary conditions that govern solid displacements and pore-water pressures. Solid displacements and water pressures are strongly coupled, in part through a boundary condition that ensures mass conservation during irreversible pore deformation that occurs along the bumpy slip surface. Feedback between this deformation and the pore-pressure field may yield complex system responses. The dual derivations of the model help explicate key assumptions. For example, the model requires that the dimensionless parameter B, defined here through normalization of Biot's equations, is much larger than one. This indicates that solid-fluid coupling forces are dominated by viscous rather than inertial effects. A tabulation of physical and kinematic variables for the rod-array experiments of Iverson and LaHusen and for various geologic phenomena shows that the model assumptions commonly are satisfied. A subsequent paper will describe model tests against experimental data. ?? 1993 International Association for Mathematical Geology.

Variables of state and charateristics for isentropic discharge phenomena of water, starting with saturation

Energy Technology Data Exchange (ETDEWEB)

Baudisch, H.

1968-03-15

The tables presented in this report contain the thermodynamic values of isentropic change of state for water in the two-phase region starting from the saturation line down to 0.01 at. The variables have been computed in the pressure range from 5-100 at. in equal pressure intervals of 5 at. and in the range from 100-170 at. in intervals of 10 at. Assuming a one-dimensional flow and a known saturation pressure, the dimensions of a discharge nozzle may be determined by interpolation of the calculated values for an isentropic discharge. 4 figs., 29 tabs., 23 refs.

Transport of Silica Colloid through Saturated Porous Media under Different Hydrogeochemical and Hydrodynamic Conditions Considering Managed Aquifer Recharge

Directory of Open Access Journals (Sweden)

Zhuo Wang

2016-11-01

Full Text Available Colloids may have an important role in regulating the structure and function of groundwater ecosystems, and may influence the migration of low solubility contaminants in groundwater. There is, however, a degree of uncertainty about how colloids behave under the variable hydrogeochemical and hydrodynamic conditions that occur during managed aquifer recharge. We used an online monitoring system to monitor the transport of silica colloid in saturated porous media under different hydrogeochemical conditions, including a range of pH values (5, 7, and 9, ionic strengths (<0.0005, 0.02, and 0.05 M, cation valences (Na+, Ca2+, flow rates (0.1, 0.2, and 0.4 mL/min. The results showed that silica colloid was more likely to deposit on the surface of porous media in acidic conditions (pH = 5 than in alkaline conditions (pH = 9, indicating that the risks of pollution from colloidal interactions would be higher when the pH of the recharge water was higher. Colloid deposition occurred when the ionic strength of the colloidal suspension increased, and bivalent cations had a greater effect than monovalent cations. This suggests that bivalent cation-rich recharge water might affect the porosity of the porous medium because of colloid deposition during the managed aquifer recharge process. As the flow rate increased, the migration ability of silica colloid increased. We simulated the migration of silica colloid in porous media with the COMSOL Multiphysics model.

Sample dimensions effect on prediction of soil water retention curve and saturated hydraulic conductivity

Science.gov (United States)

Soil water retention curve (SWRC) and saturated hydraulic conductivity (SHC) are key hydraulic properties for unsaturated zone hydrology and groundwater. Not only are the SWRC and SHC measurements time-consuming, their results are scale dependent. Although prediction of the SWRC and SHC from availab...

Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model

International Nuclear Information System (INIS)

Tucci, P.

2001-01-01

This Analysis/Model Report (AMR) documents an updated analysis of water-level data performed to provide the saturated-zone, site-scale flow and transport model (CRWMS M and O 2000) with the configuration of the potentiometric surface, target water-level data, and hydraulic gradients for model calibration. The previous analysis was presented in ANL-NBS-HS-000034, Rev 00 ICN 01, Water-Level Data Analysis for the Saturated Zone Site-Scale Flow and Transport Model (USGS 2001). This analysis is designed to use updated water-level data as the basis for estimating water-level altitudes and the potentiometric surface in the SZ site-scale flow and transport model domain. The objectives of this revision are to develop computer files containing (1) water-level data within the model area (DTN: GS010908312332.002), (2) a table of known vertical head differences (DTN: GS0109083 12332.003), and (3) a potentiometric-surface map (DTN: GS010608312332.001) using an alternate concept from that presented in ANL-NBS-HS-000034, Rev 00 ICN 01 for the area north of Yucca Mountain. The updated water-level data include data obtained from the Nye County Early Warning Drilling Program (EWDP) and data from borehole USW WT-24. In addition to being utilized by the SZ site-scale flow and transport model, the water-level data and potentiometric-surface map contained within this report will be available to other government agencies and water users for ground-water management purposes. The potentiometric surface defines an upper boundary of the site-scale flow model, as well as provides information useful to estimation of the magnitude and direction of lateral ground-water flow within the flow system. Therefore, the analysis documented in this revision is important to SZ flow and transport calculations in support of total system performance assessment

Saturation of bentonite dependent upon temperature

International Nuclear Information System (INIS)

Hausmannova, Lucie; Vasicek, Radek

2010-01-01

Document available in extended abstract form only. The fundamental idea behind the long-term safe operation of a deep repository is the use of the Multi-barrier system principle. Barriers may well differ according to the type of host rock in which the repository is located. It is assumed that the buffer in the granitic host rock environment will consist of swelling clays which boast the ideal properties for such a function i.e. low permeability, high swelling pressure, self-healing ability etc. all of which are affected primarily by mineralogy and dry density. Water content plays a crucial role in the activation of swelling pressure as well as, subsequently, in the potential self healing of the various contact areas of the numerous buffer components made from bentonite. In the case of a deep repository, a change in water content is not only connected with the possible intake of water from the host rock, but also with its redistribution owing to changes in temperature after the insertion of the heat source (disposal waste package containing spent fuel) into the repository 'nest'. The principal reason for the experimental testing of this high dry density material is the uncertainty with regard to its saturation ability (final water content or the degree of saturation) at higher temperatures. The results of the Mock-Up-CZ experiment showed that when the barrier is constantly supplied with a saturation medium over a long time period the water content in the barrier as well as the degree of saturation settle independently of temperature. The Mock-Up-CZ experiment was performed at temperatures of 30 deg. - 90 deg. C in the barrier; therefore it was decided to experimentally verify this behaviour by means of targeted laboratory tests. A temperature of 110 deg. C was added to the set of experimental temperatures resulting in samples being tested at 25 deg. C, 95 deg. C and 110 deg. C. The degree of saturation is defined as the ratio of pore water volume to pore

Recharge and Lateral Groundwater Flow Boundary Conditions for the Saturated Zone Site-Scale Flow and Transport Model

Energy Technology Data Exchange (ETDEWEB)

B. Arnold; T. Corbet

2001-12-18

The purpose of the flow boundary conditions analysis is to provide specified-flux boundary conditions for the saturated zone (SZ) site-scale flow and transport model. This analysis is designed to use existing modeling and analysis results as the basis for estimated groundwater flow rates into the SZ site-scale model domain, both as recharge at the upper (water table) boundary and as underflow at the lateral boundaries. The objective is to provide consistency at the boundaries between the SZ site-scale flow model and other groundwater flow models. The scope of this analysis includes extraction of the volumetric groundwater flow rates simulated by the SZ regional-scale flow model to occur at the lateral boundaries of the SZ site-scale flow model and the internal qualification of the regional-scale model for use in this analysis model report (AMR). In addition, the scope includes compilation of information on the recharge boundary condition taken from three sources: (1) distributed recharge as taken from the SZ regional-scale flow model, (2) recharge below the area of the unsaturated zone (UZ) site-scale flow model, and (3) focused recharge along the Fortymile Wash channel.

A new through-tubing oil-saturation measurement system

International Nuclear Information System (INIS)

Roscoe, B.A.; Adolph, R.A.; Bontemy, Y.; Cheeseborough, J.C. III; Hall, J.S.; McKeon, D.C.; Pittman, D.; Seeman, B.; Thomas, S.R. Jr.

1991-01-01

This paper reports on carbon-oxygen logging which is used primarily to estimate oil saturation in cased-hole conditions when the formation water is fresh or unknown. The drawbacks of current techniques are: slow logging speed, large tool diameter, and excessive sensitivity to borehole fluid composition. A new, slim, neutron-induced gamma ray spectroscopy logging system has been developed to overcome some of these limitations. The new logging service is called the Reservoir Saturation (RST) Tool. Initial field tests are being carried out in the Middle East. The RST tool uses multiple detectors to separate the signal contributions from the borehole and the formation. Therefore, even when the borehole fluid composition is unknown, oil saturation can be determined in addition to the borehole oil fraction. This presents the possibility of logging flowing wells, which ensures that reinvasion and crossflow will not affect the results, and eliminates the costs of well preparation

Prediction technique for minimum-heat-flux (MHF)- point condition of saturated pool boiling

International Nuclear Information System (INIS)

Nishio, Shigefumi

1987-01-01

The temperature-controlled hypothesis for the minimum-heat-flux (MHF)-point condition, in which the MHF-point temperature is regarded as the controlling factor and is expected to be independent of surface configuration and dimensions, is inductively investigated for saturated pool-boiling. In this paper such features of the MHF-point condition are experimentally proved first. Secondly, a correlation of the MHF-point temperature is developed for the effect of system pressure. Finally, a simple technique based on this correlation is presented to estimate the effects of surface configuration, dimensions and system pressure on the minimum heat flux. (author)

Freezing heat transfer within water-saturated porous media

International Nuclear Information System (INIS)

Sasaki, Akira; Aiba, Shinya; Fukusako, Shoichiro.

1990-01-01

In the present study, analytical and experimental investigations were performed so as to clarify the characteristics of freezing heat transfer in porous media saturated with water in a vertical rectangular cavity. In order to establish the momentum equation, the law of conservation of momentum was applied to the fluid in our control volume, and the equation took into account Forchheimer's extension as the resistance to flow in the porous media. Three different sizes of glass, iron and copper beads were used as the porous media in this study. The temperature of the cold wall was kept at -10degC, while that of the hot wall was varied from 2degC to 22 degC. Comparisons between the analytical results and the experimental ones show good agreement with the exception of the copper bead results. (author)

Observation of a new surface mode on a fluid-saturated permeable solid

International Nuclear Information System (INIS)

Nagy, P.B.

1992-01-01

Almost ten years ago, S. Feng and D. L. Johnson predicted the presence of a new surface mode on a fluid/fluid-saturated porous solid interface with closed surface pores [J. Acoust. Soc. Am. 74, 906 (1983)]. We found that, due to surface tension, practically closed-pore boundary conditions can prevail at an interface between a nonwetting fluid (e.g., air) and a porous solid saturated with a wetting fluid (e.g., water or alcohol). Surface wave velocity and attenuation measurements were made on alcohol-saturated porous sintered glass at 100 kHz. The experimental results show clear evidence of the new ''slow'' surface mode predicted by Feng and Johnson

Velocity Regulation in Switched Reluctance Motors under Magnetic Flux Saturation Conditions

Directory of Open Access Journals (Sweden)

Victor M. Hernández-Guzmán

2018-01-01

Full Text Available We propose a controller for velocity regulation in switched reluctance motors under magnetic flux saturation conditions. Both hysteresis and proportional control are employed in the internal electric current loops. A classical PI velocity controller is employed in the external loop. Our control law is the simplest one proposed in the literature but provided with a formal stability proof. We prove that the state is bounded having an ultimate bound which can be rendered arbitrarily small by a suitable selection of controller gains. Furthermore, this result stands when starting from any initial condition within a radius which can be arbitrarily enlarged using suitable controller gains. We present a simulation study where even convergence to zero of velocity error is observed as well as a good performance when regulating velocity in the presence of unknown step changes in external torque disturbances.

The combined effects of acidification and hypoxia on pH and aragonite saturation in the coastal waters of the California current ecosystem and the northern Gulf of Mexico

Science.gov (United States)

Feely, Richard A.; Okazaki, Remy R.; Cai, Wei-Jun; Bednaršek, Nina; Alin, Simone R.; Byrne, Robert H.; Fassbender, Andrea

2018-01-01

Inorganic carbon chemistry data from the surface and subsurface waters of the West Coast of North America have been compared with similar data from the northern Gulf of Mexico to demonstrate how future changes in CO2 emissions will affect chemical changes in coastal waters affected by respiration-induced hypoxia ([O2] ≤ 60 μmol kg-1). In surface waters, the percentage change in the carbon parameters due to increasing CO2 emissions are very similar for both regions even though the absolute decrease in aragonite saturation is much higher in the warmer waters of the Gulf of Mexico. However, in subsurface waters the changes are enhanced due to differences in the initial oxygen concentration and the changes in the buffer capacity (i.e., increasing Revelle Factor) with increasing respiration from the oxidation of organic matter, with the largest impacts on pH and CO2 partial pressure (pCO2) occurring in the colder West Coast waters. As anthropogenic CO2 concentrations begin to build up in subsurface waters, increased atmospheric CO2 will expose organisms to hypercapnic conditions (pCO2 >1000 μatm) within subsurface depths. Since the maintenance of the extracellular pH appears as the first line of defense against external stresses, many biological response studies have been focused on pCO2-induced hypercapnia. The extent of subsurface exposure will occur sooner and be more widespread in colder waters due to their capacity to hold more dissolved oxygen and the accompanying weaker acid-base buffer capacity. Under present conditions, organisms in the West Coast are exposed to hypercapnic conditions when oxygen concentrations are near 100 μmol kg-1 but will experience hypercapnia at oxygen concentrations of 260 μmol kg-1 by year 2100 under the highest elevated-CO2 conditions. Hypercapnia does not occur at present in the Gulf of Mexico but will occur at oxygen concentrations of 170 μmol kg-1 by the end of the century under similar conditions. The aragonite saturation

Similarity index between irrigation water and soil saturation extract in the experimental field of Yachay University, Ecuador

Science.gov (United States)

Carrera-Villacrés, D. V.; Sánchez-Gómez, V. P.; Portilla-Bravo, O. A.; Bolaños-Guerrón, D. R.

2017-08-01

Soil monitoring is a job that demands a lot of time and money. therefore, measuring the same parameters in the water becomes simple because it can be done in situ. The objective of this work was to find a similarity index for the validation of mathematical correlation models based on physicochemical parameters to verify if there is a balance between irrigation water and soil saturation extract in the experimental field Yachay that is known as the city of knowledge that is located in Imbabura province, Ecuador, for which, the sampling of water was carried out in two representative periods (dry and rainy). Sampling of 10 soil profiles was also performed, covering the total area; these samples were obtained results of Electrical Conductivity (EC), pH and total dissolved salts (TDS). With correlation models between soils and water, it is possible to predict concentrations of elements in the irrigation water. It was concluded that there is a balance between soil and water, so that the salts present in the soil are highly soluble, in addition, there is a high probability that the elements in the irrigation water are in the soil. In sample water, the same concentrations were found in the soil, at their saturation point, and very close to the field capacity.

Evidence of water vapor in excess of saturation in the atmosphere of Mars.

Science.gov (United States)

Maltagliati, L; Montmessin, F; Fedorova, A; Korablev, O; Forget, F; Bertaux, J-L

2011-09-30

The vertical distribution of water vapor is key to the study of Mars' hydrological cycle. To date, it has been explored mainly through global climate models because of a lack of direct measurements. However, these models assume the absence of supersaturation in the atmosphere of Mars. Here, we report observations made using the SPICAM (Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars) instrument onboard Mars Express that provide evidence of the frequent presence of water vapor in excess of saturation, by an amount far surpassing that encountered in Earth's atmosphere. This result contradicts the widespread assumption that atmospheric water on Mars cannot exist in a supersaturated state, directly affecting our long-term representation of water transport, accumulation, escape, and chemistry on a global scale.

Provision of water by halite deliquescence for Nostoc commune biofilms under Mars relevant surface conditions

Science.gov (United States)

Jänchen, Jochen; Feyh, Nina; Szewzyk, Ulrich; de Vera, Jean-Pierre P.

2016-04-01

Motivated by findings of new mineral related water sources for organisms under extremely dry conditions on Earth we studied in an interdisciplinary approach the water sorption behaviour of halite, soil component and terrestrial Nostoc commune biofilm under Mars relevant environmental conditions. Physicochemical methods served for the determination of water sorption equilibrium data and survival of heterotrophic bacteria in biofilm samples with different water contents was assured by recultivation. Deliquescence of halite provides liquid water at temperatures <273 K and may serve as water source on Mars during the morning stabilized by the CO2 atmosphere for a few hours. The protecting biofilm of N. commune is rather hygroscopic and tends to store water at lower humidity values. Survival tests showed that a large proportion of the Alphaproteobacteria dominated microbiota associated to N. commune is very desiccation tolerant and water uptake from saturated NaCl solutions (either by direct uptake of brine or adsorption of humidity) did not enhance recultivability in long-time desiccated samples. Still, a minor part can grow under highly saline conditions. However, the salinity level, although unfavourable for the host organism, might be for parts of the heterotrophic microbiota no serious hindrance for growing in salty Mars-like environments.

High speed drying of saturated steam

International Nuclear Information System (INIS)

Marty, C.; Peyrelongue, J.P.

1993-01-01

This paper describes the development of the drying process for the saturated steam used in the PWR nuclear plant turbines in order to prevent negative effects of water on turbine efficiency, maintenance costs and equipment lifetime. The high speed drying concept is based on rotating the incoming saturated steam in order to separate water which is more denser than the steam; the water film is then extracted through an annular slot. A multicellular modular equipment has been tested. Applications on high and low pressure extraction of various PWR plants are described (Bugey, Loviisa)

Degree of saturation effect on the grout-soil interface shear strength of soil nailing

Directory of Open Access Journals (Sweden)

Wang Qiong

2016-01-01

Full Text Available In the grouted soil nailing system, the bonding strength of cement grout-soil interface offers the required resistance to maintain the stability of whole structure. In practice, soil nailing applications are often placed at unsaturated conditions, such as soil slopes, shallow foundations, retaining walls and pavement structures. In these cases, the water content in the soil nail zone may increase or decrease due to rain water or dry weather, and even cannot become saturated during their design service life. In this study, the effect of water content (degree of saturation on the shear strength of interface between cement grout and sand are experimentally investigated by means of direct shear test. Meanwhile the water retention curve was determined and interface microstructure was observed. Experimental results show that the shear strength of interface changes non-monotonously with degree of saturation when the interface was prepared, due to the non-monotonousness of the cohesiveness between soil particles. The less the cohesiveness between sand particles, the more grout was observed been penetrated into the voids, and thus the larger the interface shear stress.

Bacteria transport and retention in intact calcareous soil columns under saturated flow conditions

Directory of Open Access Journals (Sweden)

Farrokhian Firouzi Ahmad

2015-06-01

Full Text Available Study of bacterial transport and retention in soil is important for various environmental applications such as groundwater contamination and bioremediation of soil and water. The main objective of this research was to quantitatively assess bacterial transport and deposition under saturated conditions in calcareous soil. A series of leaching experiments was conducted on two undisturbed soil columns. Breakthrough curves of Pseudomonas fluorescens and Cl were measured. After the leaching experiment, spatial distribution of bacteria retention in the soil columns was determined. The HYDRUS-1D one- and two-site kinetic models were used to predict the transport and deposition of bacteria in soil. The results indicated that the two-site model fits the observed data better than one-site kinetic model. Bacteria interaction with the soil of kinetic site 1 revealed relatively fast attachment and slow detachment, whereas attachment to and detachment of bacteria from kinetic site 2 was fast. Fast attachment and slow detachment of site 1 can be attributed to soil calcium carbonate that has favorable attachment sites for bacteria. The detachment rate was less than 0.02 of the attachment rate, indicating irreversible attachment of bacteria. High reduction rate of bacteria was also attributed to soil calcium carbonate.

The effect of water saturation deficit on the volume of intercellular space in laeves

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J. Czerski

2015-01-01

Full Text Available The volume of intercellular spaces in leaves at various stages of water saturation was determined by method of Czerski (1964, 1968. The investigation were performed with the following plant species: Vicia faba L., Nicotiana tabacum L. var. rustica, Solarium tuberosum L. var. Flisak, Helichrysum bracteatum Wild., Bmssica napus L. var. oleifera, Beta vulgaris L. var. saccharifera.

Numerical Study of Frequency-dependent Seismoelectric Coupling in Partially-saturated Porous Media

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Djuraev Ulugbek

2017-01-01

Full Text Available The seismoelectric phenomenon associated with propagation of seismic waves in fluid-saturated porous media has been studied for many decades. The method has a great potential to monitor subsurface fluid saturation changes associated with production of hydrocarbons. Frequency of the seismic source has a significant impact on measurement of the seismoelectric effects. In this paper, the effects of seismic wave frequency and water saturation on the seismoelectric response of a partially-saturated porous media is studied numerically. The conversion of seismic wave to electromagnetic wave was modelled by extending the theoretically developed seismoelectric coupling coefficient equation. We assumed constant values of pore radius and zeta-potential of 80 micrometers and 48 microvolts, respectively. Our calculations of the coupling coefficient were conducted at various water saturation values in the frequency range of 10 kHz to 150 kHz. The results show that the seismoelectric coupling is frequency-dependent and decreases exponentially when frequency increases. Similar trend is seen when water saturation is varied at different frequencies. However, when water saturation is less than about 0.6, the effect of frequency is significant. On the other hand, when the water saturation is greater than 0.6, the coupling coefficient shows monotonous trend when water saturation is increased at constant frequency.

Migration of Gas in Water Saturated Clays by Coupled Hydraulic-Mechanical Model

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Aliaksei Pazdniakou

2018-01-01

Full Text Available Understanding the gas migration in highly water saturated sedimentary rock formations is of great importance for safety of radioactive waste repositories which may use these host rocks as barrier. Recent experiments on drainage in argillite samples have demonstrated that they cannot be represented in terms of standard two-phase flow Darcy model. It has been suggested that gas flows along highly localized dilatant pathways. Due to very small pore size and the opacity of the material, it is not possible to observe this two-phase flow directly. In order to better understand the gas transport, a numerical coupled hydraulic-mechanical model at the pore scale is proposed. The model is formulated in terms of Smoothed Particle Hydrodynamics (SPH and is applied to simulate drainage within a sample reconstructed from the Focused Ion Beam (FIB images of Callovo-Oxfordian claystone. A damage model is incorporated to take into account the degradation of elastic solid properties due to local conditions, which may lead to formation of new pathways and thus to modifications of fluid transport. The influence of the damage model as well as the possible importance of rigid inclusions is demonstrated and discussed.

Kinetics and dynamics of nanosecond streamer discharge in atmospheric-pressure gas bubble suspended in distilled water under saturated vapor pressure conditions

KAUST Repository

Sharma, Ashish; Levko, Dmitry; Raja, Laxminarayan L; Cha, Min

2016-01-01

We perform computational studies of nanosecond streamer discharges generated in helium bubbles immersed in distilled water under atmospheric pressure conditions. The model takes into account the presence of water vapor in the gas bubble

Transport properties and pore-network structure in variably-saturated Sphagnum peat soil

DEFF Research Database (Denmark)

Hamamoto, Shoichiro; Dissanayaka, Shiromi Himalika; Kawamoto, K.

2016-01-01

Gas and water transport in peat soil are of increasing interest because of their potentially large environmental and climatic effects under different types of land use. In this research, the water retention curve (WRC), gas diffusion coefficient (Dg) and air and water permeabilities (ka and kw......) of layers in peat soil from two profiles were measured under different moisture conditions. A two-region Archie's Law (2RAL)-type model was applied successfully to the four properties; the reference point was taken at -9.8kPa of soil-water matric potential where volume shrinkage typically started to occur....... For WRC in the very decomposed peat soil, the 2RAL saturation exponents (n) obtained for both the wetter (nw) and drier regions (nd) were smaller than those for the less decomposed peat. For Dg, the saturation exponent in the wetter region was larger than that in the drier one for all layers, which...

Calcium phosphate saturation in the western Bay of Bengal

Digital Repository Service at National Institute of Oceanography (India)

Naik, S.; Reddy, C.V.G.

Temperature, inorganic phosphate concentration and pH seem to be the major factors influencing the degree of saturation of calcium phosphate in sea water. Two water regions can be demarcated in the study area based on the saturation patterns...

Investigation of Primary Dew-Point Saturator Efficiency in Two Different Thermal Environments

Science.gov (United States)

Zvizdic, D.; Heinonen, M.; Sestan, D.

2015-08-01

The aim of this paper is to describe the evaluation process of the performance of the low-range saturator (LRS), when exposed to two different thermal environments. The examined saturator was designed, built, and tested at MIKES (Centre for Metrology and Accreditation, Finland), and then transported to the Laboratory for Process Measurement (LPM) in Croatia, where it was implemented in a new dew-point calibration system. The saturator works on a single-pressure-single-pass generation principle in the dew/frost-point temperature range between and . The purpose of the various tests performed at MIKES was to examine the efficiency and non-ideality of the saturator. As a test bath facility in Croatia differs from the one used in Finland, the same tests were repeated at LPM, and the effects of different thermal conditions on saturator performance were examined. Thermometers, pressure gauges, an air preparation system, and water for filling the saturator at LPM were also different than those used at MIKES. Results obtained by both laboratories indicate that the efficiency of the examined saturator was not affected either by the thermal conditions under which it was tested or by equipment used for the tests. Both laboratories concluded that LRS is efficient enough for a primary realization of the dew/frost-point temperature scale in the range from to , with flow rates between and . It is also shown that a considerable difference of the pre-saturator efficiency, indicated by two laboratories, did not have influence to the overall performance of the saturator. The results of the research are presented in graphical and tabular forms. This paper also gives a brief description of the design and operation principle of the investigated low-range saturator.

Numerical simulation of air- and water-flow experiments in a block of variably saturated, fractured tuff from Yucca Mountain, Nevada

International Nuclear Information System (INIS)

Kwicklis, E.M.; Healy, R.W.; Thamir, F.; Hampson, D.

1998-01-01

Numerical models of water movement through variably saturated, fractured tuff have undergone little testing against experimental data collected from relatively well-controlled and characterized experiments. This report used the results of a multistage experiment on a block of variably saturated, fractured, welded tuff and associated core samples to investigate if those results could be explained using models and concepts currently used to simulate water movement in variably saturated, fractured tuff at Yucca Mountain, Nevada, the potential location of a high-level nuclear-waste repository. Aspects of the experiment were modeled with varying degrees of success. Imbibition experiments performed on cores of various lengths and diameters were adequately described by models using independently measured permeabilities and moisture-characteristic curves, provided that permeability reductions resulting from the presence of entrapped air were considered. Entrapped gas limited maximum water saturations during imbibition to approximately 0.70 to 0,80 of the fillable porosity values determined by vacuum saturation. A numerical simulator developed for application to fluid flow problems in fracture networks was used to analyze the results of air-injection tests conducted within the tuff block through 1.25-cm-diameter boreholes. These analyses produced estimates of transmissivity for selected fractures within the block. Transmissivities of other fractures were assigned on the basis of visual similarity to one of the tested fractures. The calibrated model explained 53% of the observed pressure variance at the monitoring boreholes (with the results for six outliers omitted) and 97% of the overall pressure variance (including monitoring and injection boreholes) in the subset of air-injection tests examined

Thermo-hydraulic behavior of saturated steam-water mixture in pressure vessel during injection of cold water

International Nuclear Information System (INIS)

Aya, Izuo; Kobayashi, Michiyuki; Inasaka, Fujio; Nariai, Hideki.

1983-01-01

The thermo-hydraulic behavior of saturated steam water mixture in a pressure vessel during injection of cold water was experimentally investigated with the Facility for Mixing Effect of Emergency Core Cooling Water. The dimensions of the pressure vessel used in the experiments were 284mm ID and 1,971mm height. 11 experiments were conducted without blowdown in order to comprehend the basic process excluding the effect of blowdown at injection of cold water. The initial pressure and water level, the injection flow rate and the size of injection nozzle were chosen as experimental parameters. Temperatures and void fractions at 6 elevations as well as pressure in the pressure vessel were measured, and new data especially on the pressure undershoot just after the initation of water injection and the vertical distribution of temperature and void fraction were gotten. The transients of pressure, average temperature and void fraction were caluculated using single-volume analysis code BLODAC-1V which is based on thermal equilibrium and so-called bubble gradient model. Some input parameters included in the analysis code were evaluated through the comparison of analysis with experimental data. Moreover, the observed pressure undershoot which is evaluated to be induced by a time lag of vapourization in water due to thermal nonequilibrium, was also discussed with the aid of another simple analysis model. (author)

CT-scan-monitored electrical-resistivity measurements show problems achieving homogeneous saturation

International Nuclear Information System (INIS)

Sprunt, E.S.; Davis, R.M.; Muegge, E.L.; Desai, K.P.

1991-01-01

This paper reports on x-ray computerized tomography (CT) scans obtained during measurement of the electrical resistivity of core samples which revealed some problems in obtaining uniform saturation along the lengths of the samples. The electrical resistivity of core samples is measured as a function of water saturation to determine the saturation exponent used in electric-log interpretation. An assumption in such tests is that the water saturation is uniformly distributed. Failure of this assumption can result in errors in the determination of the saturation exponent. Three problems were identified in obtaining homogeneous water saturation in two samples of a Middle Eastern carbonate grainstone: a stationary front formed in one sample at 1-psi oil/brine capillary pressure, a moving front formed at oil/brine capillary pressure ≤4 psi in samples tested in fresh mixed-wettability and cleaned water-wet states, and the heterogeneous fluid distribution caused by a rapidly moving front did not dissipate when the capillary pressure was eliminated in the samples

Strengthening and Stabilization of the Weak Water Saturated Soils Using Stone Columns

Directory of Open Access Journals (Sweden)

Sinyakov Leonid

2016-01-01

Full Text Available The article considers innovative modern materials and structures for strengthening of weak soils. In this paper describes a method of strengthening of weak saturated soils using stone columns. The method of calculating the physical-mechanical characteristics of reinforced soil mass is presented. Two approaches to determining the stress-strain state and timeframe of consolidation of strengthened soil foundation using the finite element technique in two-dimensional formulation are proposed. The first one approach it is a modeling of reinforced soil mass, where each pile is represented as a separate 2D stripe. The second approach is to the simulation of the strengthened mass the equivalent composite block with improved physical-mechanical characteristics. The use of the equivalent composite block can significantly reduce the time spent on the preparation of a design scheme. The results of calculations were compared. They show the allowable divergence of results of calculation by two methods were presented, and the efficiency of the strengthening of weak water saturated soils by stone column is proved.

Multifactorial modelling of high-temperature treatment of timber in the saturated water steam medium

Science.gov (United States)

Prosvirnikov, D. B.; Safin, R. G.; Ziatdinova, D. F.; Timerbaev, N. F.; Lashkov, V. A.

2016-04-01

The paper analyses experimental data obtained in studies of high-temperature treatment of softwood and hardwood in an environment of saturated water steam. Data were processed in the Curve Expert software for the purpose of statistical modelling of processes and phenomena occurring during this process. The multifactorial modelling resulted in the empirical dependences, allowing determining the main parameters of this type of hydrothermal treatment with high accuracy.

Using saturation water percentage data to predict mechanical composition of soils

International Nuclear Information System (INIS)

Mbagwu, J.S.C.; Okafor, D.O.

1995-04-01

One hundred and sixty-six soil samples representing eleven textural classes and having wide variations in organic matter (OM) contents and other physico-chemical properties were collected from different locations in southeastern Nigeria to study the relationship between mechanical composition and saturation water percentage (SP). The objective was to develop a prediction model for silt + clay (SC) and clay (C) contents of these soils using the SP values. The magnitude of the correlation coefficients (r) between SC or C and SP was dependent on the amount of organic matter (OM) present in the soils. For soils with ≤ 1.00% OM, the correlation (r) between SC and SP was 0.9659 (p ≤ 0.001) and that between C and SP was 0.9539 (p ≤ 0.001). For soils with ≥ 2.00% OM, the 'r' values were generally low, varying between 0.5320 and 0.2665 for SC and 0.6008 and 0.3000 for C. The best-fit regression models for predicting SC and C were developed with soils having ≤ 1.00% OM. An independent data set from 25 soil samples collected from other parts of the study area was used to test the predictive ability of the best-fit models. These models predicted SC and C accurately in soils having between 0.28 and 1.10% OM, but poorly in soils having between 1.31 and 3.91% OM. These results show that the use of saturation water percentage to predict the mechanical composition of soils is most reliable for soils with low (≤ 1.00%) OM contents. (author). 18 refs, 2 figs, 5 tabs

Numerical study of saturation steam/water mixture flow and flashing initial sub-cooled water flow inside throttling devices

CERN Multimedia

CERN. Geneva

2016-01-01

In this work, a Computational Fluid-Dynamics (CFD) approach to model this phenomenon inside throttling devices is proposed. To validate CFD results, different nozzle geometries are analyzed, comparing numerical results with experimental data. Two cases are studied: Case 1: saturation steam/water mixture flow inside 2D convergent-divergent nozzle (inlet, outlet and throat diameter of nozzle are 0.1213m, 0.0452m and 0.0191m respectively). In this benchmark, a range of total inle...

Effect of paraffin saturation in a crude oil on operation of a field

Energy Technology Data Exchange (ETDEWEB)

Trebin, G F; Kapyrin, Yu V

1968-11-01

Both theoretical and practical studies in recent years have shown that in planning operational procedures for an oil field, the paraffin saturation of the crude oil must be considered. If the crude oil is essentially saturated with paraffin at reservoir condition, then paraffin deposition can occur around the well and in the well. Temperature in the reservoir can be lowered by 2 mechanisms: (1) by injection of water below reservoir temperature, and (2) by expansion of produced gas and consequent cooling of the produced oil. Possible application of these principles to several Soviet oil fields is discussed. In the Uzen field, a preliminary investigation is under way to test the feasibility of heating the injection water to prevent paraffin deposition in the reservoir.

Simulation of the saturation process of a radwaste storage cell

International Nuclear Information System (INIS)

Robbe, M.F.; Clouard, A.

2001-01-01

This paper presents a simulation of the saturation of the barrier and the plug of a storage cell by the surrounding host rock. Generally speaking, the unsaturated barrier and plug start saturating immediately in the vicinity of the quasi-saturated host rock. Then the saturation front propagates towards the canisters and the symmetry axis. Apart from the part in contact with the plug, the barrier is saturated at about 30 years. The part of the barrier near the plug is saturated around 80 years. If the top of the plug is saturated very soon, the part in the corner near the gallery and the symmetry axis is not completely saturated after 100 years. In the site, we observe a small desaturation during the first month, at the limit with the plug and the barrier, and especially in the corner limited by both FoCa clay pieces. This transient phenomenon may be assigned to the time difference between the immediate suction of water by the unsaturated materials and the delayed water flows coming from the saturated host rock to compensate the water suction. The purpose of this computation was at once to estimate the time necessary for the saturation of the clay layers surrounding the radwaste canisters and to evaluate the hydro-mechanical behaviour of the storage cell during the saturation process. Therefore a mechanical simulation was performed using the present hydraulic results to initiate the mechanical computation. (authors)

Water saturation phase of the buffer and backfill in the KBS-3V concept. Special emphasis given to the influence of the backfill on the wetting of the buffer

International Nuclear Information System (INIS)

Boergesson, Lennart; Faelth, Billy; Hernelind, Jan

2006-08-01

The wetting and rate of saturation of the buffer and backfill materials in a KBS- V repository from the rock fractures and the rock matrix have been investigated by a large number of different finite element models and calculations. For most models the FE-code ABAQUS has been used but for investigation of the influence of trapped air in the backfill FE-code Code Bright was used. Both codes include completely coupled THM models, which have been used, but for some calculations it has been sufficient to limit the models to only use the hydraulic or thermohydraulic parts of the models. The following analyses have been made: 1. The influence of the backfill properties and wetting conditions on the water saturation phase of the buffer has been investigated with the old FEM-model used in earlier wetting calculations for SR-97. The old calculations have been updated regarding the influence of the backfill. The model is 2-dimensional with axial symmetry around the axis of the deposition hole. These calculations show that there is strong influence of wetting from the backfill if the rock is rather dry (K rock = 10 -13 m/s), while the influence is low if the rock is rather wet (K rock = 10 -12 m/s). At K rock = 10 -13 m/s the time to saturation decreases with a factor 2 in the absence of fractures and with a factor 1.5 with two fractures intersecting the hole when water is supplied from the backfill (30/70) compared to when no water is available. A completely dry rock yields very long time to saturation and of course decisive influence of the water supply from the backfill. If water is freely available at a water pressure of 5 MPa in the backfill it takes 250-500 years to reach full saturation of the buffer. If the water available in the backfill is limited to the initial amount (completely dry rock also around the tunnel and thus no addition of water from the rock in the tunnel) it will take several thousands years to reach some kind of equilibrium with a degree of

Water saturation phase of the buffer and backfill in the KBS-3V concept. Special emphasis given to the influence of the backfill on the wetting of the buffer

Energy Technology Data Exchange (ETDEWEB)

Boergesson, Lennart; Faelth, Billy [Clay Technology AB, Lund (Sweden); Hernelind, Jan [5T Engineering AB, Vaesteraas (Sweden)

2006-08-15

The wetting and rate of saturation of the buffer and backfill materials in a KBS- V repository from the rock fractures and the rock matrix have been investigated by a large number of different finite element models and calculations. For most models the FE-code ABAQUS has been used but for investigation of the influence of trapped air in the backfill FE-code Code Bright was used. Both codes include completely coupled THM models, which have been used, but for some calculations it has been sufficient to limit the models to only use the hydraulic or thermohydraulic parts of the models. The following analyses have been made: 1. The influence of the backfill properties and wetting conditions on the water saturation phase of the buffer has been investigated with the old FEM-model used in earlier wetting calculations for SR-97. The old calculations have been updated regarding the influence of the backfill. The model is 2-dimensional with axial symmetry around the axis of the deposition hole. These calculations show that there is strong influence of wetting from the backfill if the rock is rather dry (K{sub rock} = 10{sup -13} m/s), while the influence is low if the rock is rather wet (K{sub rock} = 10{sup -12} m/s). At K{sub rock} = 10{sup -13} m/s the time to saturation decreases with a factor 2 in the absence of fractures and with a factor 1.5 with two fractures intersecting the hole when water is supplied from the backfill (30/70) compared to when no water is available. A completely dry rock yields very long time to saturation and of course decisive influence of the water supply from the backfill. If water is freely available at a water pressure of 5 MPa in the backfill it takes 250-500 years to reach full saturation of the buffer. If the water available in the backfill is limited to the initial amount (completely dry rock also around the tunnel and thus no addition of water from the rock in the tunnel) it will take several thousands years to reach some kind of

Water uptake, migration and swelling characteristics of unsaturated and saturated, highly compacted bentonite

International Nuclear Information System (INIS)

Pusch, R.

1980-09-01

The report presents the results of a number of laboratory tests and field observations to form the basis of a physical and mathematical model that can be used for predicting water uptake and swelling in highly compacted bentonite components of an actual deposition plant. The clay buffer masses have been suggested as barriers in the Swedish KBS concepts. Two commercially available bentonites were used for the production of samples. The rate of water uptake suggests a mathematical model based on a simple diffusion equation. The rate is determined by the access of water and thousands of years may pass before saturation is obtained. The rate of swelling is governed by the negative pore pressure and the permeability. There is reasonable agreement with field observations. The observed swelling potential of old smectite-rich clays has offered the evidence. (G.B.)

Anisotropic Behaviour of Opalinus Clay Through Consolidated and Drained Triaxial Testing in Saturated Conditions

Science.gov (United States)

Favero, Valentina; Ferrari, Alessio; Laloui, Lyesse

2018-05-01

This paper investigates the anisotropic hydro-mechanical behaviour of Opalinus Clay shale, the host material currently being considered for the construction of a nuclear waste repository in Switzerland. Consolidated and drained triaxial tests on Opalinus Clay from the Mont Terri URL have been conducted in order to derive information on its strength and stiffness properties. Opalinus Clay specimens were tested both parallel to bedding (P-specimens) and perpendicular to bedding (S-specimens). The considered effective confining stress range (from 2 to 12 MPa) has been selected in order to reproduce possible in situ stress conditions for the repository. In this work, particular attention has been paid to the experimental procedure in order to ensure consolidated conditions and avoid generation of unwanted excess pore water pressure during drained shearing. The Skempton B parameter has been determined for all the tested specimens in order to ensure saturation. Both single-stage and multistage triaxial testing procedures were adopted in the experimental campaign. The results of the triaxial tests highlight an anisotropic elastic response of Opalinus Clay: S-specimens present a more compliant behaviour than P-specimens. The values of the Young modulus are found to increase with the increase in mean effective stress. The analysis of the peak and ultimate shear strength results reveals that the material behaves in a similar manner regardless of the considered direction of loading (P and S directions) with respect to the bedding orientation. Peak and ultimate failure envelopes for Opalinus Clay were derived for the investigated stress range.

Steam-water relative permeability

Energy Technology Data Exchange (ETDEWEB)

Ambusso, W.; Satik, C.; Home, R.N. [Stanford Univ., CA (United States)

1997-12-31

A set of relative permeability relations for simultaneous flow of steam and water in porous media have been measured in steady state experiments conducted under the conditions that eliminate most errors associated with saturation and pressure measurements. These relations show that the relative permeabilities for steam-water flow in porous media vary approximately linearly with saturation. This departure from the nitrogen/water behavior indicates that there are fundamental differences between steam/water and nitrogen/water flows. The saturations in these experiments were measured by using a high resolution X-ray computer tomography (CT) scanner. In addition the pressure gradients were obtained from the measurements of liquid phase pressure over the portions with flat saturation profiles. These two aspects constitute a major improvement in the experimental method compared to those used in the past. Comparison of the saturation profiles measured by the X-ray CT scanner during the experiments shows a good agreement with those predicted by numerical simulations. To obtain results that are applicable to general flow of steam and water in porous media similar experiments will be conducted at higher temperature and with porous rocks of different wetting characteristics and porosity distribution.

1DFEMWATER: A one-dimensional finite element model of WATER flow through saturated-unsaturated media

International Nuclear Information System (INIS)

Yeh, G.T.

1988-08-01

This report presents the development and verification of a one- dimensional finite element model of water flow through saturated- unsaturated media. 1DFEMWATER is very flexible and capable of modeling a wide range of real-world problems. The model is designed to (1) treat heterogeneous media consisting of many geologic formations; (2) consider distributed and point sources/sinks that are spatially and temporally variable; (3) accept prescribed initial conditions or obtain them from steady state simulations; (4) deal with transient heads distributed over the Dirichlet boundary; (5) handle time-dependent fluxes caused by pressure gradient on the Neumann boundary; (6) treat time-dependent total fluxes (i.e., the sum of gravitational fluxes and pressure-gradient fluxes) on the Cauchy boundary; (7) automatically determine variable boundary conditions of evaporation, infiltration, or seepage on the soil-air interface; (8) provide two options for treating the mass matrix (consistent and lumping); (9) provide three alternatives for approximating the time derivative term (Crank-Nicolson central difference, backward difference, and mid-difference); (10) give three options (exact relaxation, underrelaxation, and overrelaxation) for estimating the nonlinear matrix; (11) automatically reset the time step size when boundary conditions or source/sinks change abruptly; and (12) check mass balance over the entire region for every time step. The model is verified with analytical solutions and other numerical models for three examples

Linearity and Reversibility of Iodide Adsorption on Sediments from Hanford, Washington Under Water Saturated Conditions

International Nuclear Information System (INIS)

Um, Wooyong; Serne, R. Jeffrey; Krupka, Kenneth M.

2004-01-01

A series of adsorption and desorption experiments were completed to determine the linearity of iodide adsorption, as a function of concentration, and its reversibility onto sediment for geochemical conditions germane to the proposed disposal of low-level radioactive waste by the U.S. Department of Energy's Immobilized Low Activity Waste (ILAW) program at the Hanford Site in southeastern Washington. Iodine-129 is predicted to be one of the top three long-term risk drivers based on past performance assessment conducted for the eventual disposal of the low-level portion of radioactive wastes currently stored in underground storage tanks at Hanford, because iodide exhibits little adsorption affinity to mineral surfaces resulting in high mobility in the subsurface environment. Adsorption experiments, conducted with Hanford formation sediments and groundwater spiked with dissolved 125I (as an analog tracer for 129I), indicated that iodide adsorption was very low at pH 7.5 and could be represented by a linear isotherm up to a total concentration of 100 mg/L dissolved iodide. The linearity of iodide adsorption up to concentrations of 100 mg/L validates the use of the linear Kd construct in transport models to predict the fate and transport of 129I in subsurface systems at Hanford. The results of desorption experiments indicated that up to 60% of adsorbed iodide was readily desorbed after 14 days by the same groundwater solution. Iodide adsorption was considered to be partially reversible or weakly binding on the sediments. Even though small amount of initial iodide is retarded by adsorption reactions at mineral-water interfaces, the weak adsorption affinity results in release of iodide when iodide free pore waters and ground waters contact the contaminated sediments in the vadose zone and aquifer systems

CT-scan-monitored electrical resistivity measurements show problems achieving homogeneous saturation

International Nuclear Information System (INIS)

Sprunt, E.S.; Coles, M.E.; Davis, R.M.; Muegge, E.L.; Desai, K.P.

1991-01-01

X-ray CT scans obtained during measurement of the electrical resistivity of core samples revealed some problems in obtaining uniform saturation along the length of the sample. In this paper the electrical resistivity of core samples is measured as a function of water saturation to determine the saturation exponent, which is used in electric log interpretation. An assumption in such tests is that the water saturation is uniformly distributed. Failure of this assumption can result in errors in the determination of the saturation exponent. Three problems were identified in obtaining homogeneous water saturation in two samples of a Middle Eastern carbonate grainstone. A stationary front formed in one sample at 1 psi oil/brine capillary pressure. A moving front formed at oil/brine capillary pressures of 4 psi or less in both samples tested, in both a fresh mixed-wettability state and in a cleaned water-wet state. In these samples, the heterogeneous fluid distribution caused by a rapidly moving front did not dissipate when the capillary pressure was eliminated

Corrosion of low alloy steel containing 0.5% chromium in supercritical CO2-saturated brine and water-saturated supercritical CO2 environments

Science.gov (United States)

Wei, Liang; Gao, Kewei; Li, Qian

2018-05-01

The corrosion behavior of P110 low-Cr alloy steel in supercritical CO2-saturated brine (aqueous phase) and water-saturated supercritical CO2 (SC CO2 phase) was investigated. The results show that P110 steel primarily suffered general corrosion in the aqueous phase, while severe localized corrosion occurred in the SC CO2 phase. The formation of corrosion product scale on P110 steel in the aqueous phase divided into three stages: formation of the initial corrosion layer containing amorphous Cr(OH)3, FeCO3 and a small amount of Fe3C; transformation of initial corrosion layer to mixed layer, which consisted of FeCO3 and a small amount of Cr(OH)3 and Fe3C; growth and dissolution of the mixed layer. Finally, only a single mixed layer covered on the steel in the aqueous phase. However, the scale formed in SC CO2 phase consisted of two layers: the inner mixed layer and the dense outer FeCO3 crystalline layer.

FEMWATER: a finite-element model of water flow through saturated-unsaturated porous media

International Nuclear Information System (INIS)

Yeh, G.T.; Ward, D.S.

1980-10-01

Upon examining the Water Movement Through Saturated-Unsaturated Porous Media: A Finite-Element Galerkin Model, it was felt that the model should be modified and expanded. The modification is made in calculating the flow field in a manner consistent with the finite element approach, in evaluating the moisture-content increasing rate within the region of interest, and in numerically computing the nonlinear terms. With these modifications, the flow field is continuous everywhere in the flow regime, including element boundaries and nodal points, and the mass loss through boundaries is much reduced. Expansion is made to include four additional numerical schemes which would be more appropriate for many situations. Also, to save computer storage, all arrays pertaining to the boundary condition information are compressed to smaller dimension, and to ease the treatment of different problems, all arrays are variably dimensioned in all subroutines. This report is intended to document these efforts. In addition, in the derivation of finite-element equations, matrix component representation is used, which is believed more readable than the matrix representation in its entirety. Two identical sample problems are simulated to show the difference between the original and revised models

Performance Analysis of IEEE 802.11 DCF and IEEE 802.11e EDCA in Non-saturation Condition

Science.gov (United States)

Kim, Tae Ok; Kim, Kyung Jae; Choi, Bong Dae

We analyze the MAC performance of the IEEE 802.11 DCF and 802.11e EDCA in non-saturation condition where device does not have packets to transmit sometimes. We assume that a flow is not generated while the previous flow is in service and the number of packets in a flow is geometrically distributed. In this paper, we take into account the feature of non-saturation condition in standards: possibility of transmission performed without preceding backoff procedure for the first packet arriving at the idle station. Our approach is to model a stochastic behavior of one station as a discrete time Markov chain. We obtain four performance measures: normalized channel throughput, average packet HoL (head of line) delay, expected time to complete transmission of a flow and packet loss probability. Our results can be used for admission control to find the optimal number of stations with some constraints on these measures.

Regional groundwater modeling of the saturated zone in the vicinity of Yucca Mountain, Nevada

International Nuclear Information System (INIS)

Ahola, M.; Sagar, B.

1992-10-01

Results of groundwater modeling of the saturated zone in the vicinity of Yucca Mountain are presented. Both a regional (200 x 200 km) and subregional (50 x 50 km) model were used in the analyses. Simulations were conducted to determine the impact of various disruptive that might take place over the life span of a proposed Yucca Mountain geologic conditions repository on the groundwater flow field, as well as changes in the water-table elevations. These conditions included increases in precipitation and groundwater recharge within the regional model, changes in permeability of existing hydrogeologic barriers, a:nd the vertical intrusion of volcanic dikes at various orientations through the saturated zone. Based on the regional analysis, the rise in the water-table under Yucca Mountain due to various postulated conditions ranged from only a few meters to 275 meters. Results of the subregional model analysis, which was used to simulate intrusive dikes approximately 4 kilometers in length in the vicinity of Yucca Mountain, showed water-table rises ranging from a few meters to as much as 103 meters. Dikes oriented approximately north-south beneath Yucca Mountain produced the highest water-table rises. The conclusions drawn from this analysis are likely to change as more site-specific data become available and as the assumptions in the model are improved

Barley seed radiosensitivity following post-hydration in oxygen-, nitrogen- and nitrous oxide-saturated water, 1

International Nuclear Information System (INIS)

Singh, S.P.; Kesavan, P.C.

1990-01-01

Dry (∼3.5 and 4.0 per cent moisture content) barley seeds were exposed to 350 Gy of 60 Co-γ-rays in vacuo and post-hydrated at 4degC for 8 h in O 2 -, N 2 -, or N 2 O-saturated water. The effect of caffeine and t-butyl alcohol (t-BuOH) dissolved in the post-hydration medium on the magnitude of damage developing under these three different gaseous circumstances was studied. The post-irradiation damage and its modification by caffeine and t-BuOH was assessed in terms of 8-day-old seedling injury, peroxidase activity and total peroxides in the 8-day-old seedlings. Post-irradiation O 2 -saturated hydration caused maximal 8-day-old seedling injury, and increased peroxidase activity with concomitant reduction in total peroxides. Both caffeine and t-BuOH afforded significant radioprotection against post-irradiation O 2 -dependent damage. Post-irradiation N 2 O-saturated hydration was even more significantly radioprotective than the N 2 -saturated post-hydration. Under these circumstances, t-BuOH exerted no effect whatsoever on the N 2 - and N 2 O-mediated post-irradiation damage. Caffeine, on the other hand, significantly potentiated these two components of damage. A brief consideration of the physicochemical events which possibly account for the observed effects is presented. (author)

Water Saturation Relations and Their Diffusion-Limited Equilibration in Gas Shale: Implications for Gas Flow in Unconventional Reservoirs

Science.gov (United States)

Tokunaga, Tetsu K.; Shen, Weijun; Wan, Jiamin; Kim, Yongman; Cihan, Abdullah; Zhang, Yingqi; Finsterle, Stefan

2017-11-01

Large volumes of water are used for hydraulic fracturing of low permeability shale reservoirs to stimulate gas production, with most of the water remaining unrecovered and distributed in a poorly understood manner within stimulated regions. Because water partitioning into shale pores controls gas release, we measured the water saturation dependence on relative humidity (rh) and capillary pressure (Pc) for imbibition (adsorption) as well as drainage (desorption) on samples of Woodford Shale. Experiments and modeling of water vapor adsorption into shale laminae at rh = 0.31 demonstrated that long times are needed to characterize equilibrium in larger (5 mm thick) pieces of shales, and yielded effective diffusion coefficients from 9 × 10-9 to 3 × 10-8 m2 s-1, similar in magnitude to the literature values for typical low porosity and low permeability rocks. Most of the experiments, conducted at 50°C on crushed shale grains in order to facilitate rapid equilibration, showed significant saturation hysteresis, and that very large Pc (˜1 MPa) are required to drain the shales. These results quantify the severity of the water blocking problem, and suggest that gas production from unconventional reservoirs is largely associated with stimulated regions that have had little or no exposure to injected water. Gravity drainage of water from fractures residing above horizontal wells reconciles gas production in the presence of largely unrecovered injected water, and is discussed in the broader context of unsaturated flow in fractures.

Elasticity of water-saturated rocks as a function of temperature and pressure.

Science.gov (United States)

Takeuchi, S.; Simmons, G.

1973-01-01

Compressional and shear wave velocities of water-saturated rocks were measured as a function of both pressure and temperature near the melting point of ice to confining pressure of 2 kb. The pore pressure was kept at about 1 bar before the water froze. The presence of a liquid phase (rather than ice) in microcracks of about 0.3% porosity affected the compressional wave velocity by about 5% and the shear wave velocity by about 10%. The calculated effective bulk modulus of the rocks changes rapidly over a narrow range of temperature near the melting point of ice, but the effective shear modulus changes gradually over a wider range of temperature. This phenomenon, termed elastic anomaly, is attributed to the existence of liquid on the boundary between rock and ice due to local stresses and anomalous melting of ice under pressure.

Investigating the Factors Affecting theZahedan’s Aquifer Hydrogeochemistry Using Foctor Analysis, Saturation Indices and Composite Diagrams’ Methods

Directory of Open Access Journals (Sweden)

J. Dowlati

2014-12-01

Full Text Available Zahedan aquifer is located in the northernof Zahedanwatedshed. It is essential to evaluate the quality of groundwater resources due to proving some part of drinking water, agricultural and industrial waters of this city. In order to carry out ground water quality monitoring, and assess the controlling possesses and determine cations and anions sources of the groundwater, 26 wells were sampled and water quality parameters were measured.The results of the analysis showed that almost all of the samples proved very saline and electrical conductivity varied from 1,359 to 12,620μS cm−1. In the Zahedan aquifer, sodium, chloride and sulfate were predominant Cation and Anions respectively, and sodium-chloride Na-Cl( and sodium - sulfateNa-So4 were dominant types of the groundwater. The factor analysis of samples results indicates that the two natural and human factors controlled about the 83/30% and 74/37% of the quality variations of the groundwater respectively in October and February. The first and major factor related to the natural processes of ion exchange and dissolution had a correlation with positive loadings of EC, Ca2+, Mg2+, Na+, Cl-, K+ and So42- and controls the 65.25% of the quality variations of the ground water in October and the 58.82% in February. The second factor related toCa2+, No3- constituted the18.05% of the quality variations in October and 15.56% in February, and given the urban development and less agricultural development in the aquifer, is dependent on human activities. For the samples collected in October, the saturation indices of calcite, gypsum and dolomite minerals showed saturated condition and calcite and dolomite in February showed saturated condition for more than 60% and 90% of samples and gypsum index revealed under-saturated condition for almost all samples.The unsaturated condition of Zahedan groundwater aquifer is resulted from the insufficient time for retaining water in the aquifer to dissolve the minerals

Observability of linear systems with saturated outputs

NARCIS (Netherlands)

Koplon, R.; Sontag, E.D.; Hautus, M.L.J.

1994-01-01

We present necessary and sufficient conditions for observability of the class of output-saturated systems. These are linear systems whose output passes through a saturation function before it can be measured.

Soil Texture and Cultivar Effects on Rice (Oryza sativa, L. Grain Yield, Yield Components and Water Productivity in Three Water Regimes.

Directory of Open Access Journals (Sweden)

Fugen Dou

Full Text Available The objective of this study was to determine the effects of water regime/soil condition (continuous flooding, saturated, and aerobic, cultivar ('Cocodrie' and 'Rondo', and soil texture (clay and sandy loam on rice grain yield, yield components and water productivity using a greenhouse trial. Rice grain yield was significantly affected by soil texture and the interaction between water regime and cultivar. Significantly higher yield was obtained in continuous flooding than in aerobic and saturated soil conditions but the latter treatments were comparable to each other. For Rondo, its grain yield has decreased with soil water regimes in the order of continuous flooding, saturated and aerobic treatments. The rice grain yield in clay soil was 46% higher than in sandy loam soil averaged across cultivar and water regime. Compared to aerobic condition, saturated and continuous flooding treatments had greater panicle numbers. In addition, panicle number in clay soil was 25% higher than in sandy loam soil. The spikelet number of Cocodrie was 29% greater than that of Rondo, indicating that rice cultivar had greater effect on spikelet number than soil type and water management. Water productivity was significantly affected by the interaction of water regime and cultivar. Compared to sandy loam soil, clay soil was 25% higher in water productivity. Our results indicated that cultivar selection and soil texture are important factors in deciding what water management option to practice.

Investigation of Dynamic Properties of Water-Saturated Sand by the Results of the Inverse Experiment Technique

Science.gov (United States)

Bragov, A. M.; Balandin, Vl. V.; Kotov, V. L.; Balandin, Vl. Vl.

2018-04-01

We present new experimental results on the investigation of the dynamic properties of sand soil on the basis of the inverse experiment technique using a measuring rod with a flat front-end face. A limited applicability has been shown of the method using the procedure for correcting the shape of the deformation pulse due to dispersion during its propagation in the measuring rod. Estimates of the pulse maximum have been obtained and the results of comparison of numerical calculations with experimental data are given. The sufficient accuracy in determining the drag force during the quasi-stationary stage of penetration has been established. The parameters of dynamic compressibility and resistance to shear of water-saturated sand have been determined in the course of the experimental-theoretical analysis of the maximum values of the drag force and its values at the quasi-stationary stage of penetration. It has been shown that with almost complete water saturation of sand its shear properties are reduced but remain significant in the practically important range of penetration rates.

Biological iron oxidation by Gallionella spp. in drinking water production under fully aerated conditions.

Science.gov (United States)

de Vet, W W J M; Dinkla, I J T; Rietveld, L C; van Loosdrecht, M C M

2011-11-01

Iron oxidation under neutral conditions (pH 6.5-8) may be a homo- or heterogeneous chemically- or a biologically-mediated process. The chemical oxidation is supposed to outpace the biological process under slightly alkaline conditions (pH 7-8). The iron oxidation kinetics and growth of Gallionella spp. - obligatory chemolithotrophic iron oxidizers - were assessed in natural, organic carbon-containing water, in continuous lab-scale reactors and full-scale groundwater trickling filters in the Netherlands. From Gallionella cell numbers determined by qPCR, balances were made for all systems. The homogeneous chemical iron oxidation occurred in accordance with the literature, but was retarded by a low water temperature (13 °C). The contribution of the heterogeneous chemical oxidation was, despite the presence of freshly formed iron oxyhydroxides, much lower than in previous studies in ultrapure water. This could be caused by the adsorption of natural organic matter (NOM) on the iron oxide surfaces. In the oxygen-saturated natural water with a pH ranging from 6.5 to 7.7, Gallionella spp. grew uninhibited and biological iron oxidation was an important, and probably the dominant, process. Gallionella growth was not even inhibited in a full-scale filter after plate aeration. From this we conclude that Gallionella spp. can grow under neutral pH and fully aerated conditions when the chemical iron oxidation is retarded by low water temperature and inhibition of the autocatalytic iron oxidation. Copyright © 2011 Elsevier Ltd. All rights reserved.

An innovative technique for estimating water saturation from capillary pressure in clastic reservoirs

Science.gov (United States)

Adeoti, Lukumon; Ayolabi, Elijah Adebowale; James, Logan

2017-11-01

A major drawback of old resistivity tools is the poor vertical resolution and estimation of hydrocarbon when applying water saturation (Sw) from historical resistivity method. In this study, we have provided an alternative method called saturation height function to estimate hydrocarbon in some clastic reservoirs in the Niger Delta. The saturation height function was derived from pseudo capillary pressure curves generated using modern wells with complete log data. Our method was based on the determination of rock type from log derived porosity-permeability relationship, supported by volume of shale for its classification into different zones. Leverette-J functions were derived for each rock type. Our results show good correlation between Sw from resistivity based method and Sw from pseudo capillary pressure curves in wells with modern log data. The resistivity based model overestimates Sw in some wells while Sw from the pseudo capillary pressure curves validates and predicts more accurate Sw. In addition, the result of Sw from pseudo capillary pressure curves replaces that of resistivity based model in a well where the resistivity equipment failed. The plot of hydrocarbon pore volume (HCPV) from J-function against HCPV from Archie shows that wells with high HCPV have high sand qualities and vice versa. This was further used to predict the geometry of stratigraphic units. The model presented here freshly addresses the gap in the estimation of Sw and is applicable to reservoirs of similar rock type in other frontier basins worldwide.

Site-Scale Saturated Zone Flow Model

International Nuclear Information System (INIS)

G. Zyvoloski

2003-01-01

The purpose of this model report is to document the components of the site-scale saturated-zone flow model at Yucca Mountain, Nevada, in accordance with administrative procedure (AP)-SIII.lOQ, ''Models''. This report provides validation and confidence in the flow model that was developed for site recommendation (SR) and will be used to provide flow fields in support of the Total Systems Performance Assessment (TSPA) for the License Application. The output from this report provides the flow model used in the ''Site-Scale Saturated Zone Transport'', MDL-NBS-HS-000010 Rev 01 (BSC 2003 [162419]). The Site-Scale Saturated Zone Transport model then provides output to the SZ Transport Abstraction Model (BSC 2003 [164870]). In particular, the output from the SZ site-scale flow model is used to simulate the groundwater flow pathways and radionuclide transport to the accessible environment for use in the TSPA calculations. Since the development and calibration of the saturated-zone flow model, more data have been gathered for use in model validation and confidence building, including new water-level data from Nye County wells, single- and multiple-well hydraulic testing data, and new hydrochemistry data. In addition, a new hydrogeologic framework model (HFM), which incorporates Nye County wells lithology, also provides geologic data for corroboration and confidence in the flow model. The intended use of this work is to provide a flow model that generates flow fields to simulate radionuclide transport in saturated porous rock and alluvium under natural or forced gradient flow conditions. The flow model simulations are completed using the three-dimensional (3-D), finite-element, flow, heat, and transport computer code, FEHM Version (V) 2.20 (software tracking number (STN): 10086-2.20-00; LANL 2003 [161725]). Concurrently, process-level transport model and methodology for calculating radionuclide transport in the saturated zone at Yucca Mountain using FEHM V 2.20 are being

Virus movement in soil during saturated and unsaturated flow.

Science.gov (United States)

Lance, J C; Gerba, C P

1984-02-01

Virus movement in soil during saturated and unsaturated flow was compared by adding poliovirus to sewage water and applying the water at different rates to a 250-cm-long soil column equipped with ceramic samplers at different depths. Movement of viruses during unsaturated flow of sewage through soil columns was much less than during saturated flow. Viruses did not move below the 40-cm level when sewage water was applied at less than the maximum infiltration rate; virus penetration in columns flooded with sewage was at least 160 cm. Therefore, virus movement in soils irrigated with sewage should be less than in flooded groundwater recharge basins or in saturated soil columns. Management of land treatment systems to provide unsaturated flow through the soil should minimize the depth of virus penetration. Differences in virus movement during saturated and unsaturated flow must be considered in the development of any model used to simulate virus movement in soils.

Strength and Biot's coefficient for high-porosity oil- or water-saturated chalk

DEFF Research Database (Denmark)

Andreassen, Katrine Alling

. The Biot coefficient states the degree of cementation or how the pore pressure contributes to the strain resulting from an external load for a porous material. It is here calculated from dynamic measurements and correlated with the strength of outcrop chalk characterized by the onset of pore collapse...... during hydrostatic loading. The hypothesis is that the Biot coefficient and the theory of poroelasticity may cover the fluid effect by including the increased fluid bulk modulus from oil to water. A high number of test results for both oil- and water-saturated high-porosity outcrop chalk show correlation......In the petroleum industry it is relevant to know the Biot coefficient for establishing the effective stresses present in both the overburden and for the reservoir interval. When depleting a reservoir it is important to estimate the settlement through the strain imposed by the effective stress. Also...

A Study on the Coupled Model of Hydrothermal-Salt for Saturated Freezing Salinized Soil

Directory of Open Access Journals (Sweden)

Xudong Zhang

2017-01-01

Full Text Available Water and heat interact in the process of freezing for the saturated soil. And for the salinized soil, water, heat, and salt interact in the freezing process, because salinized soil has soluble salt. In this paper, a one-dimensional mathematical coupled model of hydraulic-thermal-salt is established. In the model, Darcy’s law, law of conservation of energy, and law of conservation of mass are applied to derive the equations. Consider that a saturated salinized soil column is subjected to the condition of freezing to model the moisture migration and salt transport. Both experiment and numerical simulation under the same condition are developed in the soil column. Then the moisture content and salt content between simulation and experiment are compared. The result indicates that simulation matches well with the experiment data, and after 96 hours, the temperature distribution becomes stable, freezing front reaches a stable position, and a lot of unfrozen water has time to migrate. Besides, the excess salt precipitates when the concentration is greater than the solubility, and the precipitation is distributed discontinuously. These results can provide reference for engineering geology and environmental engineering in cold region and saline soil area.

Corrosion of iron and low alloyed steel within a water saturated brick of clay under anaerobic deep geological disposal conditions: An integrated experiment

International Nuclear Information System (INIS)

Martin, F.A.; Bataillon, C.; Schlegel, M.L.

2008-01-01

The aim of this study was to determine the corrosion behaviour of iron and low alloyed steels under simulated geological disposal conditions, related to long-term disposal of nuclear wastes in the site of Bure (Meuse-Haute Marne, Champagne, France). The dedicated experiment was a fully integrated set-up: three different bars of material (iron, steel or nickel) have been introduced inside a solid block of clay, which has been saturated with synthetic Bure water and maintained at 90 deg. C during 8 months. Two types of clay have been tested: first, a compacted MX80 (Wyoming, USA) and second, argilite directly taken from the Bure site (Callovo-Oxfordian). In situ electrochemistry has been performed: impedance spectra, chronopotentiometry... The samples have been analysed using a combination of techniques, such as SEM, XRD, EDS, μXAS, μRaman, gravimetry after desquamation. In both cases, the steel or the iron seemed to passivate in contact with the clay. Post-processing of the EIS determined the corrosion rates and the changes in the kinetics have been noticed. The post mortem analysis of the corrosion products showed in both cases the presence of an internal layer made of magnetite (Raman, EDX). The external layer was made of partially Ca-substituted siderite (Fe 1-x Ca x CO 3 ), which could play an extra role in the passivation. Moreover, the samples embedded in the Bure argilite presented an intermediate unique layer containing Fe, O, Na and Si. This study suggests the corrosion products started to react with the silica issued from the dissolution of the Bure clay minerals, resulting in clay minerals neo-formation and in corrosion kinetic changes

Competition between two wetland macrophytes under different levels of sediment saturation

Directory of Open Access Journals (Sweden)

Feng Li

2015-02-01

Full Text Available Plant-plant interactions have been widely studied under various environmental conditions. However, in wetland ecosystems how plant interactions change in response to variation in sediment saturation remains largely unclear, even though different levels of sediment saturation play important roles in determining plant growth performance in wetland ecosystems. To this end, a competition experiment with two typical wetland species, Carex brevicuspis (neighbor plant and Polygonum hydropiper (target plant, was conducted in a target-neighbor design. Two water levels (0 cm and -40 cm water levels representing waterlogged and drained sediments, respectively and three neighbor plant densities (0 plants m-2, 400 plants m-2, and 1600 plants m-2 were tested in a factorial design. Biomass accumulation of P. hydropiper decreased along with enhanced C. brevicuspis density in the waterlogged treatment. However, in the drained treatment, biomass accumulation did not change under two C. brevicuspis densities. Above-ground relative neighbor effect index (ARNE and relative neighbor effect index (RNE of C. brevicuspis on P. hydropiper increased along with enhanced C. brevicuspis density only under waterlogged conditions. The below-ground relative neighbor effect index (BRNE was not affected at the different water level and density treatments. The below-ground mass fraction of P. hydropiper was much higher in the waterlogged treatment than it was in the drained one, especially with no C. brevicuspis treatment. However, the leaf mass fraction displayed the opposite pattern. The longest root length of P. hydropiper was much shorter under waterlogged treatment than under the drained treatment. These results suggest that the competition intensity of C. brevicuspis to P. hydropiper increased along with increasing C. brevicuspis density only under waterlogged conditions. Moreover, this study also confirms that P. hydropiper can acclimate to water stress mainly through

Scaling behavior of microbubbles rising in water-saturated porous media

Science.gov (United States)

Kong, X.; Ma, Y.; Scheuermann, A.; Bringemeier, D.; Galindo-Torres, S. A.; Saar, M. O.; Li, L.

2015-12-01

Gas transport in the form of discrete microbubbles in saturated porous media is of importance in a number of processes relevant to many geo-environmental and engineering systems such as bubbling of greenhouse gases in river and sea beds, hydrocarbon gas migration in coal cleats and rock fractures, and air sparging for remediation of soil contaminated with volatile organic compounds. Under the assumption of no or minor volume expansion during gravity-driven migration, the transport of a single microbubble can be well described using various drag force models. However, not enough attention has been paid to the collective behavior of microbubbles during their ascend as a plume through the saturated porous medium, involving dynamic interactions between individual bubbles, bubbles and the ambient fluid, as well as bubbles and the solid matrix. With our quasi-2D, lab-scale microbubble migration experiments, where bubbles are continuously released from a diffuser at the bottom of a porous bed of hydrated gel beads, we establish a scaling relationship between the gas (bubble) release rate and various characteristic parameters of the bubble plume, such as plume tip velocity, plume width, and breakthrough time of the plume front. We find that the characteristic width of the bubble plume varies as a power of both the gas release rate and the bed thickness, with exponents of 0.2 and 0.4, respectively. Moreover, the characteristic breakthrough time also scales with both the gas release rate and the bed thickness with power-law exponents of -0.4 and 1.2, respectively. The mean pore-water velocity of the circulating ambient water also follows a power-law relationship with the gas release rate being an exponent of 0.6 of the gas release rate. This can be quantitatively proven using a simplified momentum exchange model together with the above power-law exponents for the bubble plume. These analyses on the experimental results are carried out on the basis of non

Kinetics and dynamics of nanosecond streamer discharge in atmospheric-pressure gas bubble suspended in distilled water under saturated vapor pressure conditions

KAUST Repository

Sharma, Ashish

2016-09-08

We perform computational studies of nanosecond streamer discharges generated in helium bubbles immersed in distilled water under atmospheric pressure conditions. The model takes into account the presence of water vapor in the gas bubble for an accurate description of the discharge kinetics. We find that the dynamic characteristics of the streamer discharge are different at low and high positive trigger voltages with the axial streamer evolution dominant for low voltages and a surface hugging mode favored for high voltages. We also find a substantial difference in initiation, transition and evolution stages of discharge for positive and negative trigger voltages with the volumetric distribution of species in the streamer channel much more uniform for negative trigger voltages on account of the presence of multiple streamers. We observe that the presence of water vapor does not affect the breakdown voltage even for oversaturated conditions but significantly influences the composition of dominant species in the trail of the streamer as well as the flux of the dominant species on the bubble surface. © 2016 IOP Publishing Ltd.

Experimental study and modeling of gas diffusion through partially water saturated porous media. Application to Vycor glasses, geo-polymers and CEM V cement pastes

International Nuclear Information System (INIS)

Boher, C.

2012-01-01

This work documents the relationship that exists between the transfer properties of a material (pore size distribution, total porosity accessible to water, water saturation degree), and its diffusion coefficient. For this sake, materials having a quasi mono modal porosity are used: Vycor glasses and geo-polymers. We also use materials having a complex porosity: CEM V cement pastes. The use of Vycor glasses and geo-polymers allows quantifying the gas diffusion coefficient through materials having known pores size, as a function of their water saturation degree. The use of cement pastes allows checking if it is possible to decompose the diffusion coefficient of a complex porosity material, in an assembling of diffusion coefficients of quasi mono modal porosity materials. For this sake, the impact of pore network arrangement on the diffusion coefficient is studied in great details. This study is divided into three parts:1)Measurement of the geometric characteristics of materials porous network by means of the mercury intrusion porosimetry, water porosimetry, isotherms of nitrogen sorption / desorption, and water desorption tests. 2) Measurement of the materials diffusion coefficient, as a function of their relative humidity storage, and their water saturation degree. 3) Modeling the diffusion coefficient of the materials, and study the impact of the pore network (tortuosity, pores connection). (author) [fr

Investigation of Wyoming Bentonite Hydration in Dry to Water-Saturated Supercritical CO2: Implications for Caprock Integrity

Science.gov (United States)

Loring, J. S.; Chen, J.; Thompson, C.; Schaef, T.; Miller, Q. R.; Martin, P. F.; Ilton, E. S.; Qafoku, O.; Felmy, A. R.; Rosso, K. M.

2012-12-01

The effectiveness of geologic sequestration as an enterprise for CO2 storage depends partly on the reactivity of supercritical CO2 (scCO2) with caprock minerals. Injection of scCO2 will displace formation water, and the pore space adjacent to overlying caprocks could eventually be dominated by dry to water-saturated scCO2. Caprock formations have high concentrations of clay minerals, including expandable montmorillonites. Water-bearing scCO2 is highly reactive and capable of hydrating or dehydrating clays, possibly leading to porosity and permeability changes that directly impact caprock performance. Dehydration will cause montmorillonite clay minerals in caprocks to contract, thereby decreasing solid volume and possibly increasing caprock permeability and porosity. On the other hand, water intercalation will cause these clays to expand, thereby increasing solid volume and possibly leading to self-sealing of caprock fractures. Pacific Northwest National Laboratory's Carbon Sequestration Initiative is developing capabilities for studying wet scCO2-mineral reactions in situ. Here, we introduce novel in situ infrared (IR) spectroscopic instrumentation that enables quantitative titrations of reactant minerals with water in scCO2. Results are presented for the infrared spectroscopic titrations of Na-, Ca-, and Mg-saturated Wyoming betonites with water over concentrations ranging from zero to scCO2 saturated. These experiments were carried out at 50°C and 90 bar. Transmission IR spectroscopy was used to measure concentrations of water dissolved in the scCO2 or intercalated into the clays. The titration curves evaluated from the transmission-IR data are compared between the three types of clays to assess the effects of the cation on water partitioning. Single-reflection attenuated total reflection (ATR) IR spectroscopy was used to collect the spectrum of the clays as they hydrate at every total water concentration during the titration. Clay hydration is evidenced by

Analysis of an SEIR Epidemic Model with Saturated Incidence and Saturated Treatment Function

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Jinhong Zhang

2014-01-01

Full Text Available The dynamics of SEIR epidemic model with saturated incidence rate and saturated treatment function are explored in this paper. The basic reproduction number that determines disease extinction and disease survival is given. The existing threshold conditions of all kinds of the equilibrium points are obtained. Sufficient conditions are established for the existence of backward bifurcation. The local asymptotical stability of equilibrium is verified by analyzing the eigenvalues and using the Routh-Hurwitz criterion. We also discuss the global asymptotical stability of the endemic equilibrium by autonomous convergence theorem. The study indicates that we should improve the efficiency and enlarge the capacity of the treatment to control the spread of disease. Numerical simulations are presented to support and complement the theoretical findings.

Effect of Collagen Matrix Saturation on the Surface Free Energy of Dentin using Different Agents.

Science.gov (United States)

de Almeida, Leopoldina de Fátima Dantas; Souza, Samilly Evangelista; Sampaio, Aline Araújo; Cavalcanti, Yuri Wanderley; da Silva, Wander José; Del Bel Cur, Altair A; Hebling, Josimeri

2015-07-01

The surface free energy of conditioned-dentin is one of the factors that interfere with monomeric infiltration of the interfibrillar spaces. Saturation of the tooth matrix with different substances may modulate this energy and, consequently, the wettability of the dentin. To evaluate the influence of different substances used to saturate conditioned-dentin on surface free energy (SFE) of this substrate. Dentin blocks (4 × 7 × 1 mm, n = 6/ group), obtained from the roots of bovine incisors, were etched using phosphoric acid for 15 seconds, rinsed and gently dried. The surfaces were treated for 60 seconds with: ultra-purified water (H20-control); ethanol (EtOH), acetone (ACT), chlorhexidine (CHX), ethylenediaminetetraacetic acid (EDTA); or sodium hypochlorite (NaOCl). The tooth surfaces were once again dried with absorbent paper and prepared for SFE evaluation using three standards: water, formamide and bromonaphthalene. Analysis of variance (ANOVA) and Dunnet's tests (a = 0.05) were applied to the data. Ethylenediaminetetraacetic acid was the only substance that caused a change to the contact angle for the standards water and formamide, while only EtOH influenced the angles formed between formamide and the dentin surface. None of the substances exerted a significant effect for bromonaphtha-lene. In comparison to the control, only EDTA and NaOCl altered both polar components of the SFE. Total SFE was increased by saturation of the collagen matrix by EDTA and reduced when NaOCl was used. Saturation of the collagen matrix by EDTA and EtOH changed the surface free energy of the dentin. In addition, the use of NaOCl negatively interfered with the properties evaluated. The increase of surface free energy and wettability of the dentin surface would allow higher penetration of the the adhesive system, which would be of importance to the clinical success of resin-dentin union.

A free boundary problem describing the saturated-unsaturated flow in a porous medium

Directory of Open Access Journals (Sweden)

Gabriela Marinoschi

2004-01-01

Full Text Available This paper presents a functional approach to a nonlinear model describing the complete physical process of water infiltration into an unsaturated soil, including the saturation occurrence and the advance of the wetting front. The model introduced in this paper involves a multivalued operator covering the simultaneous saturated and unsaturated flow behaviors and enhances the study of the displacement of the free boundary between these two flow regimes. The model resides in Richards' equation written in pressure form with an initial condition and boundary conditions which in this work express the inflow due to the rain on the soil surface on the one hand, and characterize a certain permeability corresponding to the underground boundary, on the other hand. Existence, uniqueness, and regularity results for the transformed model in diffusive form, that is, for the moisture of the soil, and the existence of the weak solution for the pressure form are proved in the 3D case. The main part of the paper focuses on the existence of the free boundary between the saturated and unsaturated parts of the soil, and this is proved, in the 1D case, for certain stronger assumptions on the initial data and boundary conditions.

Numerical modeling of variably saturated flow and transport, 881 Hillside at Rocky Flats Plant, Jefferson County, Colorado

International Nuclear Information System (INIS)

Fedors, R.W.; Warner, J.W.

1993-01-01

This study characterizes the unconfined groundwater flow and chemical transport in a thin veneer of colluvial and alluvial Quaternary sediments on the 881 Hillslope at Rocky Flats Plant, Jefferson County, Colorado. Colluvial deposits with a varying thickness of 1.5 to 6.7 meters mantle a 255 meter steeply dipping hillslope. Saturated and the similar material types. A two-dimensional finite element code for variably saturated conditions is used to obtain steady state flow conditions from which water contents and Darcy velocities are used for transient contaminant transport modeling. The migration of an absorptive solute is modeled over a twenty year period using the transport portion of the two-dimensional finite element code. Different potential scenarios for the source area are compared with actual well sample data. The solutes considered for this study are Trichloroethene (TCE) and tetrachloroethene (PCE) dissolved in the water phase

Predicting liquid water saturation through differently structured cathode gas diffusion media of a proton exchange Membrane Fuel Cell

NARCIS (Netherlands)

Akhtar, N.; Kerkhof, P.J.A.M.

2012-01-01

The role of gas diffusion media with differently structured properties have been examined with emphasis on the liquid water saturation within the cathode of a proton exchange membrane fuel cell (PEMFC). The cathode electrode consists of a gas diffusion layer (GDL), a micro-porous layer and a

On the formation of a moving redox-front by α-radiolysis of compacted water saturated bentonite

International Nuclear Information System (INIS)

Eriksen, T.E.; Ndalamba, P.

1988-12-01

The formation of an expanding volume containing the radiolytically formed oxidants H 2 O 2 and O 2 has been studied in α-irradiated compacted water saturated bentonite (ρ = 2.12 gxcm -3 ). The G-values (0.67±0.05), (0.64±0.07) for H 2 O 2 and O 2 respectively are in fair agreement with the corresponding G-values obtained in experiments with synthetic ground water. From the leaching of γ-irradiated bentonite it is concluded that only a fraction of the Fe 2+ content is easily accessible as scavenger for the radiolytically formed oxidants. (orig.)

Effect of gravity on colloid transport through water-saturated columns packed with glass beads: modeling and experiments.

Science.gov (United States)

Chrysikopoulos, Constantinos V; Syngouna, Vasiliki I

2014-06-17

The role of gravitational force on colloid transport in water-saturated columns packed with glass beads was investigated. Transport experiments were performed with colloids (clays: kaolinite KGa-1b, montmorillonite STx-1b). The packed columns were placed in various orientations (horizontal, vertical, and diagonal) and a steady flow rate of Q = 1.5 mL/min was applied in both up-flow and down-flow modes. All experiments were conducted under electrostatically unfavorable conditions. The experimental data were fitted with a newly developed, analytical, one-dimensional, colloid transport model. The effect of gravity is incorporated in the mathematical model by combining the interstitial velocity (advection) with the settling velocity (gravity effect). The results revealed that flow direction influences colloid transport in porous media. The rate of particle deposition was shown to be greater for up-flow than for down-flow direction, suggesting that gravity was a significant driving force for colloid deposition.

Experimental characterization of the concrete behaviour under high confinement: influence of the saturation ratio and of the water/cement ratio

International Nuclear Information System (INIS)

Vu, X.H.

2007-08-01

The objective of this thesis is to experimentally characterize the influence of the saturation ratio and of the water/cement ratio of concrete on its behaviour under high confinement. This thesis lies within a more general scope of the understanding of concrete behaviour under severe loading situations (near field detonation or ballistic impacts). A near field detonation or an impact on a concrete structure generate very high levels of stress associated with complex loading paths in the concrete material. To validate concrete behaviour models, experimental results are required. The work presented in this thesis concerns tests conducted using a static triaxial press that allows to obtain stress levels of the order of the giga Pascal. The porous character of concrete and the high confinement required on the one hand, a development of a specimen protection device, and on the other hand, a development of an instrumentation with strain gauges, which is unprecedented for such high confinements. Hydrostatic and triaxial tests, conducted on the one hand on model materials and on the other hand on concrete, allowed to validate the developed experimental procedures as well as the technique of strain and stress measurements. The studies concerning the influence of the saturation ratio and of the water/cement ratio of concrete on its behaviour required the formulation of a plain baseline concrete and of two modified concretes with different water/cement ratios. The analysis of triaxial tests performed on the baseline concrete shows that the saturation ratio of concrete has a major influence on its static behaviour under high confinement. This influence is particularly marked for the concrete loading capacity and for the shape of limit state curves for saturation ratios greater than 50%. The concrete loading capacity increases with the confinement pressure for tests on dry concrete whereas beyond a given confinement pressure, it remains limited for wet or saturated concrete

Near-saturated surface soil hydraulic properties under different land uses in the St Denis National Wildlife Area, Saskatchewan, Canada

Science.gov (United States)

Bodhinayake, Waduwawatte; Si, Bing Cheng

2004-10-01

Surface soil hydraulic properties are key factors controlling the partition of rainfall and snowmelt into runoff and soil water storage, and their knowledge is needed for sound land management. The objective of this study was to evaluate the effects of three land uses (native grass, brome grass and cultivated) on surface soil hydraulic properties under near-saturated conditions at the St Denis National Wildlife Area, Saskatchewan, Canada. For each land use, water infiltration rates were measured using double-ring and tension infiltrometers at -0.3, -0.7, -1.5 and -2.2 kPa pressure heads. Macroporosity and unsaturated hydraulic properties of the surface soil were estimated. Mean field-saturated hydraulic conductivity (Kfs), unsaturated hydraulic conductivity at -0.3 kPa pressure head, inverse capillary length scale () and water-conducting macroporosity were compared for different land uses. These parameters of the native grass and brome grass sites were significantly (p 1.36 × 10-4 m in diameter in the three land uses. Land use modified near-saturated hydraulic properties of surface soil and consequently may alter the water balance of the area by changing the amount of surface runoff and soil water storage.

Studies on plant extracts as corrosion inhibitors for mild steel in air saturated water

International Nuclear Information System (INIS)

Mohamad Daud; Abdul Razak Daud; Zainal Abidin Sidi

1988-01-01

The effectiveness in inhibiting corrosion by garlic, soya bean, and tobacco extracts and their combinations in air saturated water at ambient temperature were studied by using electrochemical corrosion test. The range of inhibitor concentration studied was from 0.1 to 1.0 g/l. The variations of corrosion potential and corrosion current density was recorded and the results showed that the extracts have inhibitive properties in the corrosion of mild stee. The effectiveness of the inhibitors is in the following order: extract mixture > tobacco > garlic > soya bean extracts. (author)

Electrical conductivity modeling in fractal non-saturated porous media

Science.gov (United States)

Wei, W.; Cai, J.; Hu, X.; Han, Q.

2016-12-01

The variety of electrical conductivity in non-saturated conditions is important to study electric conduction in natural sedimentary rocks. The electrical conductivity in completely saturated porous media is a porosity-function representing the complex connected behavior of single conducting phases (pore fluid). For partially saturated conditions, the electrical conductivity becomes even more complicated since the connectedness of pore. Archie's second law is an empirical electrical conductivity-porosity and -saturation model that has been used to predict the formation factor of non-saturated porous rock. However, the physical interpretation of its parameters, e.g., the cementation exponent m and the saturation exponent n, remains questionable. On basis of our previous work, we combine the pore-solid fractal (PSF) model to build an electrical conductivity model in non-saturated porous media. Our theoretical porosity- and saturation-dependent models contain endmember properties, such as fluid electrical conductivities, pore fractal dimension and tortuosity fractal dimension (representing the complex degree of electrical flowing path). We find the presented model with non-saturation-dependent electrical conductivity datasets indicate excellent match between theory and experiments. This means the value of pore fractal dimension and tortuosity fractal dimension change from medium to medium and depends not only on geometrical properties of pore structure but also characteristics of electrical current flowing in the non-saturated porous media.

Influence of saturation degree and role of suction in unsaturated soils behaviour: application to liquefaction

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Vernay Mathilde

2016-01-01

Full Text Available The effect of the pore fluid compressibility on liquefaction has been studied by various authors. But few papers have been published about the role of suction in cyclic behavior of unsaturated soils. Most of these works use Skempton coefficient B as a reference in terms of saturation degree to analyze their results. The use of B in experimental conditions is convenient, but is not accurate when studying liquefaction behavior, since effects of suction are neglected. In this paper, the influence of saturation degree on mechanical behavior of a soil under dynamic loads is studied. Cyclic undrained triaxial tests were performed on sand samples, under various levels of saturation. Soil-water characteristic curve was used, in order to study influence of suction. The first results confirm that when the degree of saturation decreases, the resistance increases. Initial positive suction tends to stiffen the soil. It also appears that the presence of air delays the occurrence of liquefaction, but doesn’t prevent it. Indeed, liquefaction is observed, whether the soil is saturated or not.

Pre-study on cementation processes in bentonite buffer under uneven saturation and temperature gradient

International Nuclear Information System (INIS)

Jaervinen, Joonas; Muurinen, Arto; Tanhua-Tyrkkoe, Merja

2012-01-01

Document available in extended abstract form only. Under final disposal conditions the uneven and slow saturation together with heat from the canister can lead to a situation where water vaporizes in certain areas in bentonite. The evaporation of ion rich water leads to enrichment of ions and precipitation of the components which may e.g. cement montmorillonite layers together and cause some changes in the bentonite properties. To study the cementation in bentonite buffer under uneven and slow saturation conditions the experimental setup was pre-modelled, constructed and tested. The experimental setups consist of a cylindrical cell (d:100 mm and h:100 mm), adsorption cells, heating system, hydration system, cooling system, sensors and a data acquisition system. A schematic drawing of the experimental equipment is presented in Figure 1. In the cell the hydration end of the bentonite was covered only partly by the sinter and the access of water to bentonite was thus limited. The cell was also equipped with holes in the upper part of the cylinder to allow the water vapour to escape from the cell. The released water vapour is collected on an adsorption material in the adsorption cells. Thermal and hydrological properties of the experimental system were pre-modelled in 2D by using TOUGH2, version 2.0. The aim of the model was to see if the planned experimental set-up leads to the wanted conditions, within reasonable time and to find justifiable parameters for experimental setup. An eleven months long pre-experiment was carried out to get preliminary understanding how the experimental arrangement works. After the experiment the cell was dismantled and water content, bulk density, CEC, exchangeable cations, poorly crystalline iron oxides and silicates, chloride, sulphate and carbonate were analysed and pH measured. The low water content and high chloride concentration next to the heater indicated movement of chloride ions from the hydration surface towards the heater and

Diffusion of helium and estimated diffusion coefficients of hydrogen dissolved in water-saturated, compacted Ca-montmorillonite

International Nuclear Information System (INIS)

Higashihara, Tomohiro; Sato, Seichi; Ohashi, Hiroshi; Otsuka, Teppei

2001-01-01

The diffusion coefficients of hydrogen gas dissolved in water-saturated, compacted montmorillonite are required to estimate the performance of bentonite buffer materials for geological disposal of nuclear waste. As part of the effort to determine the diffusion coefficients, the diffusion coefficients of helium in water-saturated, compacted calcium montmorillonite (Ca-montmorillonite) were determined as a function of dry density, 0.78 to 1.37x10 3 kg m -3 , by a transient diffusion method. The diffusion coefficients were from 8.3x10 -10 m 2 s -1 at 0.78x10 3 kgm -3 to 2.8x10 -10 m 2 s -1 at 1.37x10 3 kgm -3 . The data obtained by this diffusion experiment of helium were highly reproducible. The diffusion coefficients of helium in Ca-montmorillonite were somewhat larger than those previously obtained for helium in sodium montmorillonite (Na-montmorillonite). The diffusion coefficients of hydrogen gas in the montmorillonites were roughly estimated using the diffusion coefficients of helium. These estimates were based on assumptions that both helium and hydrogen molecules are non-adsorptive and that the geometric factors in the compacted montmorillonites are approximately the same for diffusion of helium and diffusion of hydrogen. (author)

Archaeol: An Indicator of Methanogenesis in Water-Saturated Soils

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Katie L. H. Lim

2012-01-01

Full Text Available Oxic soils typically are a sink for methane due to the presence of high-affinity methanotrophic Bacteria capable of oxidising methane. However, soils experiencing water saturation are able to host significant methanogenic archaeal communities, potentially affecting the capacity of the soil to act as a methane sink. In order to provide insight into methanogenic populations in such soils, the distribution of archaeol in free and conjugated forms was investigated as an indicator of fossilised and living methanogenic biomass using gas chromatography-mass spectrometry with selected ion monitoring. Of three soils studied, only one organic matter-rich site contained archaeol in quantifiable amounts. Assessment of the subsurface profile revealed a dominance of archaeol bound by glycosidic headgroups over phospholipids implying derivation from fossilised biomass. Moisture content, through control of organic carbon and anoxia, seemed to govern trends in methanogen biomass. Archaeol and crenarchaeol profiles differed, implying the former was not of thaumarcheotal origin. Based on these results, we propose the use of intact archaeol as a useful biomarker for methanogen biomass in soil and to track changes in moisture status and aeration related to climate change.

Experimental study on distributed optical fiber-based approach monitoring saturation line in levee engineering

Science.gov (United States)

Su, Huaizhi; Li, Hao; Kang, Yeyuan; Wen, Zhiping

2018-02-01

Seepage is one of key factors which affect the levee engineering safety. The seepage danger without timely detection and rapid response may likely lead to severe accidents such as seepage failure, slope instability, and even levee break. More than 90 percent of levee break events are caused by the seepage. It is very important for seepage behavior identification to determine accurately saturation line in levee engineering. Furthermore, the location of saturation line has a major impact on slope stability in levee engineering. Considering the structure characteristics and service condition of levee engineering, the distributed optical fiber sensing technology is introduced to implement the real-time observation of saturation line in levee engineering. The distributed optical fiber temperature sensor system (DTS)-based monitoring principle of saturation line in levee engineering is investigated. An experimental platform, which consists of DTS, heating system, water-supply system, auxiliary analysis system and levee model, is designed and constructed. The monitoring experiment of saturation line in levee model is implemented on this platform. According to the experimental results, the numerical relationship between moisture content and thermal conductivity in porous medium is identified. A line heat source-based distributed optical fiber method obtaining the thermal conductivity in porous medium is developed. A DTS-based approach is proposed to monitor the saturation line in levee engineering. The embedment pattern of optical fiber for monitoring saturation line is presented.

Pre-Saturation Technique of the Recycled Aggregates: Solution to the Water Absorption Drawback in the Recycled Concrete Manufacture.

Science.gov (United States)

García-González, Julia; Rodríguez-Robles, Desirée; Juan-Valdés, Andrés; Morán-Del Pozo, Julia Mª; Guerra-Romero, M Ignacio

2014-09-01

The replacement of natural aggregates by recycled aggregates in the concrete manufacturing has been spreading worldwide as a recycling method to counteract the large amount of construction and demolition waste. Although legislation in this field is still not well developed, many investigations demonstrate the possibilities of success of this trend given that concrete with satisfactory mechanical and durability properties could be achieved. However, recycled aggregates present a low quality compared to natural aggregates, the water absorption being their main drawback. When used untreated in concrete mix, the recycled aggregate absorb part of the water initially calculated for the cement hydration, which will adversely affect some characteristics of the recycled concrete. This article seeks to demonstrate that the technique of pre-saturation is able to solve the aforementioned problem. In order to do so, the water absorption of the aggregates was tested to determine the necessary period of soaking to bring the recycled aggregates into a state of suitable humidity for their incorporation into the mixture. Moreover, several concrete mixes were made with different replacement percentages of natural aggregate and various periods of pre-saturation. The consistency and compressive strength of the concrete mixes were tested to verify the feasibility of the proposed technique.

Impact of Reservoir Fluid Saturation on Seismic Parameters: Endrod Gas Field, Hungary

Science.gov (United States)

El Sayed, Abdel Moktader A.; El Sayed, Nahla A.

2017-12-01

Outlining the reservoir fluid types and saturation is the main object of the present research work. 37 core samples were collected from three different gas bearing zones in the Endrod gas field in Hungary. These samples are belonging to the Miocene and the Upper - Lower Pliocene. These samples were prepared and laboratory measurements were conducted. Compression and shear wave velocity were measured using the Sonic Viewer-170-OYO. The sonic velocities were measured at the frequencies of 63 and 33 kHz for compressional and shear wave respectively. All samples were subjected to complete petrophysical investigations. Sonic velocities and mechanical parameters such as young’s modulus, rigidity, and bulk modulus were measured when samples were saturated by 100%-75%-0% brine water. Several plots have been performed to show the relationship between seismic parameters and saturation percentages. Robust relationships were obtained, showing the impact of fluid saturation on seismic parameters. Seismic velocity, Poisson’s ratio, bulk modulus and rigidity prove to be applicable during hydrocarbon exploration or production stages. Relationships among the measured seismic parameters in gas/water fully and partially saturated samples are useful to outline the fluid type and saturation percentage especially in gas/water transitional zones.

Transport and Retention of Carboxymethylcellulose-Modified Carbon Nanotube-Magnetite Nanohybrids in Water-Saturated Porous Media

Science.gov (United States)

Wang, D.; Su, C.

2017-12-01

Carbon-metal oxide nanohybrids (NHs) are increasingly recognized as the next-generation, promising group of nanomaterials for solving emerging environmental issues and challenges. This research, for the first time, systematically explored the transport and retention of the multifunctional carbon nanotube-magnetite (CNT-Fe3O4) NHs in water-saturated porous media under environmentally relevant physicochemical conditions. An environment-benign macromolecule, carboxymethylcellulose (CMC), was employed to stabilize the NHs. Classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory and colloid transport model were used to describe the transport and retention of the NHs. Our results showed that transport of the magnetic CNT-Fe3O4 NHs was lower than that of the parent CNT due to greater aggregation (induced by magnetic attraction) during transport. The DLVO theory well-interpreted the NHs' transport; and secondary minimum played dominant roles in NHs' retention. A novel transport feature, an initial low and following sharp peaks occurred frequently in the NHs' breakthrough curves; and the magnitude and location of both transport peaks varied with different experimental conditions due to the interplay between variability of the fluid viscosity and aggregation-dispersion nature of the NHs. Very promisingly, the estimated maximum transport distance of NHs using the Tufenkji-Elimelech equation ranged between 0.38-46 m, supporting the feasibility of employing the magnetically recyclable CNT-Fe3O4 NHs for in-situ nanoremediation of contaminated soils, sediment aquifers, and groundwater.

Nuclear magnetic resonance characterization of the stationary dynamics of partially saturated media during steady-state infiltration flow

Science.gov (United States)

Rassi, Erik M.; Codd, Sarah L.; Seymour, Joseph D.

2011-01-01

Flow in porous media and the resultant hydrodynamics are important in fields including but not limited to the hydrology, chemical, medical and petroleum industries. The observation and understanding of the hydrodynamics in porous media are critical to the design and optimal utilization of porous media, such as those seen in trickle-bed reactors, medical filters, subsurface flows and carbon sequestration. Magnetic resonance (MR) provides for a non-invasive technique that can probe the hydrodynamics on pore and bulk scale lengths; many previous works have characterized fully saturated porous media, while rapid MR imaging (MRI) methods in particular have previously been applied to partially saturated flows. We present time- and ensemble-averaged MR measurements to observe the effects on a bead pack partially saturated with air under flowing water conditions. The 10 mm internal diameter bead pack was filled with 100 μm borosilicate glass beads. Air was injected into the bead pack as water flowed simultaneously through the sample at 25 ml h-1. The initial partially saturated state was characterized with MRI density maps, free induction decay (FID) experiments, propagators and velocity maps before the water flow rate was increased incrementally from 25 to 500 ml h-1. After the maximum flow rate of 500 ml h-1, the MRI density maps, FID experiments, propagators and velocity maps were repeated and compared to the data taken before the maximum flow rate. This work shows that a partially saturated single-phase flow has global flow dynamics that return to characteristic flow statistics once a steady-state high flow rate has been reached. This high flow rate pushed out a significant amount of the air in the bead pack and caused the return of a preferential flow pattern. Velocity maps indicated that local flow statistics were not the same for the before and after blow out conditions. It has been suggested and shown previously that a flow pattern can return to

Nuclear magnetic resonance characterization of the stationary dynamics of partially saturated media during steady-state infiltration flow

International Nuclear Information System (INIS)

Rassi, Erik M; Codd, Sarah L; Seymour, Joseph D

2011-01-01

Flow in porous media and the resultant hydrodynamics are important in fields including but not limited to the hydrology, chemical, medical and petroleum industries. The observation and understanding of the hydrodynamics in porous media are critical to the design and optimal utilization of porous media, such as those seen in trickle-bed reactors, medical filters, subsurface flows and carbon sequestration. Magnetic resonance (MR) provides for a non-invasive technique that can probe the hydrodynamics on pore and bulk scale lengths; many previous works have characterized fully saturated porous media, while rapid MR imaging (MRI) methods in particular have previously been applied to partially saturated flows. We present time- and ensemble-averaged MR measurements to observe the effects on a bead pack partially saturated with air under flowing water conditions. The 10 mm internal diameter bead pack was filled with 100 μm borosilicate glass beads. Air was injected into the bead pack as water flowed simultaneously through the sample at 25 ml h -1 . The initial partially saturated state was characterized with MRI density maps, free induction decay (FID) experiments, propagators and velocity maps before the water flow rate was increased incrementally from 25 to 500 ml h -1 . After the maximum flow rate of 500 ml h -1 , the MRI density maps, FID experiments, propagators and velocity maps were repeated and compared to the data taken before the maximum flow rate. This work shows that a partially saturated single-phase flow has global flow dynamics that return to characteristic flow statistics once a steady-state high flow rate has been reached. This high flow rate pushed out a significant amount of the air in the bead pack and caused the return of a preferential flow pattern. Velocity maps indicated that local flow statistics were not the same for the before and after blow out conditions. It has been suggested and shown previously that a flow pattern can return to similar

WATER CONDITIONING FOR FOOD INDUSTRY USES

Directory of Open Access Journals (Sweden)

RAISA NASTAS

2011-03-01

Full Text Available Water conditioning for food industry uses. Tap (drinkingwater from many localities of Moldova doesn’t always correspond to the “Sanitarystandards for drinking water quality” or to the requirements of the “Regulation fornon-alcoholic beverages”, requiring the need for additional purification/conditioning. This paper presents research regarding the removal/adsorption of themain pollutants in tap water (iron, manganese, aluminum, humic substances,trihalomethanes on supports of local carbon adsorbents made from vegetableproducts (stones of peach and plum, walnut shells. Experiments were performedin dynamic conditions in columns of carbon adsorbents. As work solutions wasused tap water where pollutants have been introduced in amounts equivalent to 3maximum allowable concentrations. Carbonaceous adsorbents used forremoval/adsorption of pollutants in dynamic conditions, reveal a capacity of up to1:400 volumes adsorbent: solution before breakthrough. Combined filter, utilizingactive carbons, was constructed and tested for conditioning of tap water forbeverage and food production. The results demonstrated efficient remove oforganic substances and heavy metals by filtering of about 700 volumes of waterper volume of filter.

Simulation of consolidation in partially saturated soil materials

International Nuclear Information System (INIS)

Narasimhan, T.N.

1982-03-01

Partially saturated soil materials undergo consolidation, heave, collapse and failure due to changes in pore fluid pressure. The precise nature of the mechanics of such deformations is only poorly understood at present. Experimental evidence has shown that the volume change behavior of unsaturated soils cannot be adequately explained through changes in effective stress, even when a saturation dependent parameter is incorporated into the definition of effective stress. Two independent stress-state variables, involving combinations of total stress, pore air pressure and pore water pressure, are required to characterize volume changes and saturation changes in the partially saturated state. In general, two coupled conservation equations, one for the water-phase and the other for the air-phase need to be solved in order to predict the deformation behavior of unsaturated soils. If directional displacements and changes in the stress-field are required, then the conservation equations are to be integrated with an additional set of multi-dimensional force balance equations. For lack of a sufficient understanding of elastic constants such as Poisson's Ratio and Lame's constants as applied to unsaturated soils, little has been achieved so far in integrating the conservation equations and the force balance equations. For the long-term modeling of consolidation with respect to uranium mill tailings, it may be acceptable and economical to solve a single conservation equation for water, assuming that the air-phase is continuous and is at atmospheric pressure everywhere in the soil. The greatest challenge to modeling consolidation in the unsaturated zone at the presnt time is to develop enough experimental data defining the variation of void ratio and saturation with reference to the two chosen stress-state variables

Soil Water Retention and Relative Permeability for Full Range of Saturation

Energy Technology Data Exchange (ETDEWEB)

Zhang, Z. F.

2010-09-28

Common conceptual models for unsaturated flow often rely on the oversimplified representation of medium pores as a bundle of cylindrical capillaries and assume that the matric potential is attributed to capillary forces only. The adsorptive surface forces are ignored. It is often assumed that aqueous flow is negligible when a soil is near or at the residual water content. These models are successful at high and medium water contents but often give poor results at low water contents. These models do not apply to conditions at which water content is less than the residual water content. We extend the lower bound of existing water-retention functions and conductivity models from residual water content to the oven-dry condition (i.e., zero water content) by defining a state-dependent, residual-water content for a soil drier than a critical value. Furthermore, a hydraulic conductivity model for smooth uniform spheres was modified by introducing a correction factor to describe the film flow-induced hydraulic conductivity for natural porous media. The total unsaturated hydraulic conductivity is the sum of those due to capillary and film flow. The extended retention and conductivity models were verified with six datasets from the literature. Results show that, when the soil is at high and intermediate water content, there is no difference between the un-extended and the extended models; when the soil is at low water content, the un-extended models overestimate the water content but under-estimate the conductivity while the extended models match the retention and conductivity measurements well.

Damping Effect of an Unsaturated-Saturated System on Tempospatial Variations of Pressure Head and Specific Flux

Science.gov (United States)

Yang, C.; Zhang, Y. K.; Liang, X.

2014-12-01

Damping effect of an unsaturated-saturated system on tempospatialvariations of pressurehead and specificflux was investigated. The variance and covariance of both pressure head and specific flux in such a system due to a white noise infiltration were obtained by solving the moment equations of water flow in the system and verified with Monte Carlo simulations. It was found that both the pressure head and specific flux in this case are temporally non-stationary. The variance is zero at early time due to a deterministic initial condition used, then increases with time, and approaches anasymptotic limit at late time.Both pressure head and specific flux arealso non-stationary in space since the variance decreases from source to sink. The unsaturated-saturated systembehavesasa noise filterand it damps both the pressure head and specific flux, i.e., reduces their variations and enhances their correlation. The effect is stronger in upper unsaturated zone than in lower unsaturated zone and saturated zone. As a noise filter, the unsaturated-saturated system is mainly a low pass filter, filtering out the high frequency components in the time series of hydrological variables. The damping effect is much stronger in the saturated zone than in the saturated zone.

Influence of Soil Management on Water Retention from Saturation to Oven Dryness and Dominant Soil Water States in a Vertisol under Crop Rotation

Science.gov (United States)

Vanderlinden, Karl; Pachepsky, Yakov; Pederera, Aura; Martinez, Gonzalo; Espejo, Antonio Jesus; Giraldez, Juan Vicente

2014-05-01

Unique water transfer and retention properties of Vertisols strongly affect their use in rainfed agriculture in water-limited environments. Despite the agricultural importance of the hydraulic properties of those soils, water retention data dryer than the wilting point are generally scarce, mainly as a result of practical constraints of traditional water retention measurement methods. In this work we provide a detailed description of regionalized water retention data from saturation to oven dryness, obtained from 54 minimally disturbed topsoil (0-0.05m) samples collected at a 3.5-ha experimental field in SW Spain where conventional tillage (CT) and direct drilling (DD) is compared in a wheat-sunflower-legume crop rotation on a Vertisol. Water retention was measured from saturation to oven dryness using sand and sand-kaolin boxes, a pressure plate apparatus and a dew point psychrometer, respectively. A common shape of the water retention curve (WRC) was observed in both tillage systems, with a strong discontinuity in its slope near -0.4 MPa and a decreasing spread from the wet to the dry end. A continuous function, consisting of the sum of a double exponential model (Dexter et al, 2008) and the Groenevelt and Grant (2004) model could be fitted successfully to the data. Two inflection points in the WRC were interpreted as boundaries between the structural and the textural pore spaces and between the textural and the intra-clay aggregate pore spaces. Water retention was significantly higher in DD (ptillage and compaction, increasing and decreasing the amount of the largest pores in CT and DD, respectively, but resulting in a proportionally larger pore space with relevant pore-sizes for water dynamics and agronomic performance. Significant differences in water retention and equivalent pore-sizes at the dry end of the WRC could be associated with the higher organic matter content found in DD. These results explain the superior performance of DD over CT in satisfying

Nuclear Magnetic Resonance and Elastic Wave Velocity of Chalk Saturated with Brines Containing Divalent Ions

DEFF Research Database (Denmark)

Katika, Konstantina; Alam, Mohammad Monzurul; Fabricius, Ida Lykke

divided into groups of three and each group was saturated either with deionized water, calcite equilibrated water, or sodium chloride, magnesium chloride and calcium chloride solutions of the same ionic strength. Saturation with solutions that contain divalent ions caused major shifts in the distribution...... of the relaxation time. Core samples saturated with calcium chloride solution relaxed slower and those saturated with magnesium chloride solution relaxed faster than the rest of the samples. Along with the changes in relaxation the samples experienced smaller velocities of elastic waves when saturated with MgCl2...

Air Sparging Versus Gas Saturated Water Injection for Remediation of Volatile LNAPL in the Borden Aquifer

Science.gov (United States)

Barker, J.; Nelson, L.; Doughty, C.; Thomson, N.; Lambert, J.

2009-05-01

In the shallow, rather homogeneous, unconfined Borden sand aquifer, field trials of air sparging (Tomlinson et al., 2003) and pulsed air sparging (Lambert et al., 2009) have been conducted, the latter to remediate a residual gasoline source emplaced below the water table. As well, a supersaturated (with CO2) water injection (SWI) technology, using the inVentures inFusion system, has been trialed in two phases: 1. in the uncontaminated sand aquifer to evaluate the radius of influence, extent of lateral gas movement and gas saturation below the water table, and 2. in a sheet pile cell in the Borden aquifer to evaluate the recovery of volatile hydrocarbon components (pentane and hexane) of an LNAPL emplaced below the water table (Nelson et al., 2008). The SWI injects water supersaturated with CO2. The supersaturated injected water moves laterally away from the sparge point, releasing CO2 over a wider area than does gas sparging from a single well screen. This presentation compares these two techniques in terms of their potential for remediating volatile NAPL components occurring below the water table in a rather homogeneous sand aquifer. Air sparging created a significantly greater air saturation in the vicinity of the sparge well than did the CO2 system (60 percent versus 16 percent) in the uncontaminated Borden aquifer. However, SWI pushed water, still supersaturated with CO2, up to about 2.5 m from the injection well. This would seem to provide a considerable advantage over air sparging from a point, in that gas bubbles are generated at a much larger radius from the point of injection with SWI and so should involve additional gas pathways through a residual NAPL. Overall, air sparging created a greater area of influence, defined by measurable air saturation in the aquifer, but air sparging also injected about 12 times more gas than was injected in the SWI trials. The pulsed air sparging at Borden (Lambert et al.) removed about 20 percent (4.6 kg) of gasoline

Regional coupling of unsaturated and saturated flow and transport modeling - implementation at an alpine foothill aquifer in Austria

Science.gov (United States)

Klammler, G.; Rock, G.; Kupfersberger, H.; Fank, J.

2012-04-01

interval of every hydrotope vertical profile until the lowest observed groundwater table is reached. The fluctuation range of the phreatic surface is also discretized in 10 cm intervals and used as outflow boundary condition. By this procedure, the influence of the groundwater table on the water and nitrate mass leaving the unsaturated can be considered taken into account varying soil horizons. To cover saturated flow in the WLF aquifer a 2-dimensional transient horizontal flow and solute transport model is set up. A sequential coupling between the two models is implemented, i.e. a unidirectional transfer of recharge and nitrate mass outflow from the hydrotopes to the saturated compartment. For this purpose, a one-time assignment between the spatial discretization of the hydrotopes and the finite element mesh has to be set up. The resulting groundwater table computed for a given time step with the input from SIMWASER/STOTRASIM is then used to extract the corresponding water and nitrate mass values from the look-up table to be used for the consecutive time step. This process is being repeated until the end of the simulation period. Within this approach there is no direct feedback between the unsaturated and the saturated aquifer compartment, i.e. there is no simultaneous (within the same time step) update of the pressure head - unsaturated head relationship at the soil and the phreatic surface (like is shown e.g. in Walsum and Groedendijk, 2008). For the dominating coarse sand conditions of the WLF aquifer we believe that this simplification is not of further relevance. For higher soil moisture contents (i.e. almost full saturation near the groundwater table) the curve returns to specific retention within a short vertical distance. Thus, there might only be mutual impact between soil and phreatic surface conditions for shallow groundwater tables. However, it should be mentioned here that all other processes in the two compartments (including capillary rise due to clay rich

Experimental and numerical study on the fracture of rocks during injection of CO2-saturated water

Science.gov (United States)

Li, Qi; Wu, Zhishen; Lei, Xing-Lin; Murakami, Yutaka; Satoh, Takashi

2007-02-01

Geological sequestration of CO2 into depleted hydrocarbon reserviors or saline aquifers presents the enormous potential to reduce greenhouse gas emission from fossil fuels. However, it may give rise to a complicated coupling physical and chemical process. One of the processes is the hydro-mechanical impact of CO2 injection. During the injection project, the increase of pore pressures of storing formations can induce the instability, which finally results in a catastrophic failure of disposal sites. This paper focuses mainly on the role of CO2-saturated water in the fracturing behavior of rocks. To investigate how much the dissolved CO2 can influence the pore pressure change of rocks, acoustic emission (AE) experiments were performed on sandstone and granite samples under triaxial conditions. The main innovation of this paper is to propose a time dependent porosity method to simulate the abrupt failure process, which is observed in the laboratory and induced by the pore pressure change due to the volume dilatancy of rocks, using a finite element scheme associated with two-phase characteristics. The results successfully explained the phenomena obtained in the physical experiments.

Biodiesel production by two-stage transesterification with ethanol by washing with neutral water and water saturated with carbon dioxide.

Science.gov (United States)

Mendow, G; Veizaga, N S; Sánchez, B S; Querini, C A

2012-08-01

Industrial production of ethyl esters is impeded by difficulties in purifying the product due to high amounts of soap formed during transesterification. A simple biodiesel wash process was developed that allows successful purification of samples containing high amounts of soap. The key step was a first washing with neutral water, which removed the soaps without increasing the acidity or affecting the process yield. Afterward, the biodiesel was washed with water saturated with CO(2), a mild acid that neutralized the remaining soaps and extracted impurities. The acidity, free-glycerine, methanol and soaps concentrations were reduced to very low levels with high efficiency, and using non-corrosive acids. Independently of the initial acidity, it was possible to obtain biodiesel within EN14214 specifications. The process included the recovery of soaps by hydrolysis and esterification, making it possible to obtain the theoretical maximum amount of biodiesel. Copyright © 2012 Elsevier Ltd. All rights reserved.

Pre-Saturation Technique of the Recycled Aggregates: Solution to the Water Absorption Drawback in the Recycled Concrete Manufacture †

Science.gov (United States)

García-González, Julia; Rodríguez-Robles, Desirée; Juan-Valdés, Andrés; Morán-del Pozo, Julia Mª; Guerra-Romero, M. Ignacio

2014-01-01

The replacement of natural aggregates by recycled aggregates in the concrete manufacturing has been spreading worldwide as a recycling method to counteract the large amount of construction and demolition waste. Although legislation in this field is still not well developed, many investigations demonstrate the possibilities of success of this trend given that concrete with satisfactory mechanical and durability properties could be achieved. However, recycled aggregates present a low quality compared to natural aggregates, the water absorption being their main drawback. When used untreated in concrete mix, the recycled aggregate absorb part of the water initially calculated for the cement hydration, which will adversely affect some characteristics of the recycled concrete. This article seeks to demonstrate that the technique of pre-saturation is able to solve the aforementioned problem. In order to do so, the water absorption of the aggregates was tested to determine the necessary period of soaking to bring the recycled aggregates into a state of suitable humidity for their incorporation into the mixture. Moreover, several concrete mixes were made with different replacement percentages of natural aggregate and various periods of pre-saturation. The consistency and compressive strength of the concrete mixes were tested to verify the feasibility of the proposed technique. PMID:28788188

Effect of Saturated Near Surface on Nitrate and Ammonia Nitrogen Losses in Surface Runoff at the Loess Soil Hillslope

Directory of Open Access Journals (Sweden)

Yu-bin Zhang

2010-01-01

Full Text Available Water pollution from agricultural fields is a global problem and cause of eutrophication of surface waters. A laboratory study was designed to evaluate the effects of near-surface hydraulic gradients on NO3–N and NH4–N losses in surface runoff from soil boxes at 27% slope undersimulated rainfall of a loess soil hillslope. Experimental treatments included two near-surface hydraulic gradients (free drainage, FD; saturation, SA, three fertilizer application rates (control, no fertilizer input; low, 120 kg N ha-1; high, 240 kg N ha-1, and simulated rainfall of 100 mm h-1 was applied for 70 min. The results showed that saturated near-surface soil moisture had dramatic effects on NO3–N and NH4–N losses and water quality. Under the low fertilizer treatment, average NO3–N concentrations in runoff water of SA averaged 2.2 times greater than that of FD, 1.6 times greater for NH4–N. Under the high fertilizer treatment, NO3–N concentrations in runoff water from SA averaged 5.7 times greater than that of FD, 4.3 times greater for NH4–N. Nitrogen loss formed with NO3–N is dominant during the event, but not NH4–N. Under the SA condition, the total loss of NO3–N from low fertilizer treatment was 34.2 to 42.3% of applied nitrogen, while under the FD treatment that was 3.9 to 6.9%. However, the total loss of NH4–N was less than 1% of applied nitrogen. These results showed that saturated condition could make significant contribution to water quality problems.

Assessing geotechnical centrifuge modelling in addressing variably saturated flow in soil and fractured rock.

Science.gov (United States)

Jones, Brendon R; Brouwers, Luke B; Van Tonder, Warren D; Dippenaar, Matthys A

2017-05-01

The vadose zone typically comprises soil underlain by fractured rock. Often, surface water and groundwater parameters are readily available, but variably saturated flow through soil and rock are oversimplified or estimated as input for hydrological models. In this paper, a series of geotechnical centrifuge experiments are conducted to contribute to the knowledge gaps in: (i) variably saturated flow and dispersion in soil and (ii) variably saturated flow in discrete vertical and horizontal fractures. Findings from the research show that the hydraulic gradient, and not the hydraulic conductivity, is scaled for seepage flow in the geotechnical centrifuge. Furthermore, geotechnical centrifuge modelling has been proven as a viable experimental tool for the modelling of hydrodynamic dispersion as well as the replication of similar flow mechanisms for unsaturated fracture flow, as previously observed in literature. Despite the imminent challenges of modelling variable saturation in the vadose zone, the geotechnical centrifuge offers a powerful experimental tool to physically model and observe variably saturated flow. This can be used to give valuable insight into mechanisms associated with solid-fluid interaction problems under these conditions. Findings from future research can be used to validate current numerical modelling techniques and address the subsequent influence on aquifer recharge and vulnerability, contaminant transport, waste disposal, dam construction, slope stability and seepage into subsurface excavations.

Soil hydraulic properties near saturation, an improved conductivity model

DEFF Research Database (Denmark)

Børgesen, Christen Duus; Jacobsen, Ole Hørbye; Hansen, Søren

2006-01-01

of commonly used hydraulic conductivity models and give suggestions for improved models. Water retention and near saturated and saturated hydraulic conductivity were measured for a variety of 81 top and subsoils. The hydraulic conductivity models by van Genuchten [van Genuchten, 1980. A closed-form equation...... for predicting the hydraulic conductivity of unsaturated soils. Soil Sci. Soc. Am. J. 44, 892–898.] (vGM) and Brooks and Corey, modified by Jarvis [Jarvis, 1991. MACRO—A Model of Water Movement and Solute Transport in Macroporous Soils. Swedish University of Agricultural Sciences. Department of Soil Sciences....... Optimising a matching factor (k0) improved the fit considerably whereas optimising the l-parameter in the vGM model improved the fit only slightly. The vGM was improved with an empirical scaling function to account for the rapid increase in conductivity near saturation. Using the improved models...

Stability of the barium–benzo-15-crown-5 complex in nitrobenzene saturated with water

Directory of Open Access Journals (Sweden)

E. MAKRLÍK

2006-11-01

Full Text Available From extraction experiments and g-activity measurements, the exchange extraction constant corresponding to the equilibrium Ba2+(aq + SrL22+(nb D BaL22+(nb + Sr2+(aq occurring in the two-phase water–nitrobenzene system (L =benzo-15-crown-5; aq = aqueous phase, nb = nitrobenzene phase was evaluated as log Kex (Ba2+, SrL22+ = 0.3 ± 0.1. Furthermore, the stability constant of the benzo-15-crown-5–barium complex in nitrobenzene saturated with water was calculated for the temperature of 25 °C: log bnb (BaL22+=13.3±0.1.

Modelling of the physical behaviour of water saturated clay barriers. Laboratory tests, material models and finite element application

International Nuclear Information System (INIS)

Boergesson, L.; Johannesson, L.E.; Sanden, T.; Hernelind, J.

1995-09-01

This report deals with laboratory testing and modelling of the thermo-hydro-mechanical (THM) properties of water saturated bentonite based buffer materials. A number of different laboratory tests have been performed and the results are accounted for. These test results have lead to a tentative material model, consisting of several sub-models, which is described in the report. The tentative model has partly been adapted to the material models available in the finite element code ABAQUS and partly been implemented and incorporated in the code. The model that can be used for ABAQUS calculations agrees with the tentative model with a few exceptions. The model has been used in a number of verification calculations, simulating different laboratory tests, and the results have been compared with actual measurements. These calculations show that the model generally can be used for THM calculations of the behaviour of water saturated buffer materials, but also that there is still a lack of some understanding. It is concluded that the available model is relevant for the required predictions of the THM behaviour but that a further improvement of the model is desirable

Nonlinear saturation of the Rayleigh Taylor instability

International Nuclear Information System (INIS)

Das, A.; Mahajan, S.; Kaw, P.; Sen, A.; Benkadda, S.; Verga, A.

1997-01-01

The problem of the nonlinear saturation of the 2 dimensional Rayleigh Taylor instability is re-examined to put various earlier results in a proper perspective. The existence of a variety of final states can be attributed to the differences in the choice of boundary conditions and initial conditions in earlier numerical modeling studies. Our own numerical simulations indicate that the RT instability saturates by the self consistent generation of shear flow even in situations (with periodic boundaries) where, in principle, an infinite amount of gravitational energy can be tapped. Such final states can be achieved for suitable values of the Prandtl number. (author)

Saturated-unsaturated flow to a well with storage in a compressible unconfined aquifer

Science.gov (United States)

Mishra, Phoolendra Kumar; Neuman, Shlomo P.

2011-05-01

Mishra and Neuman (2010) developed an analytical solution for flow to a partially penetrating well of zero radius in a compressible unconfined aquifer that allows inferring its saturated and unsaturated hydraulic properties from responses recorded in the saturated and/or unsaturated zones. Their solution accounts for horizontal as well as vertical flows in each zone. It represents unsaturated zone constitutive properties in a manner that is at once mathematically tractable and sufficiently flexible to provide much improved fits to standard constitutive models. In this paper we extend the solution of [2010] to the case of a finite diameter pumping well with storage; investigate the effects of storage in the pumping well and delayed piezometer response on drawdowns in the saturated and unsaturated zones as functions of position and time; validate our solution against numerical simulations of drawdown in a synthetic aquifer having unsaturated properties described by the [1980]- [1976] model; use our solution to analyze 11 transducer-measured drawdown records from a seven-day pumping test conducted by University of Waterloo researchers at the Canadian Forces Base Borden in Ontario, Canada; validate our parameter estimates against manually-measured drawdown records in 14 other piezometers at Borden; and compare (a) our estimates of aquifer parameters with those obtained on the basis of all these records by [2008], (b) on the basis of 11 transducer-measured drawdown records by [2007], (c) our estimates of van Genuchten-Mualem parameters with those obtained on the basis of laboratory drainage data from the site by [1992], and (d) our corresponding prediction of how effective saturation varies with elevation above the initial water table under static conditions with a profile based on water contents measured in a neutron access tube at a radial distance of about 5 m from the center of the pumping well. We also use our solution to analyze 11 transducer-measured drawdown

Study of sorption and diffusion of 137Cs in compacted bentonite saturated with saline water at 60degC

International Nuclear Information System (INIS)

Suzuki, Satoru; Haginuma, Masashi; Suzuki, Kazunori

2007-01-01

The effect of compaction of bentonite on the sorption behavior of 137 Cs was studied for the safety assessment of the high level radioactive waste. The diffusion coefficients (effective D e and apparent D a ) and the distribution coefficient for sorption K d for 137 Cs in compacted and dispersed bentonite saturated with saline water were investigated at 60degC by four different sorption and diffusion experiments: the in-diffusion, through-diffusion, reservoir-depletion and batch sorption experiments. The system of the through-diffusion experiment was carefully designed to maintain the boundary conditions of constant concentration at each end of the specimen. D e and D a were found to be reproducible and showed good consistency among three of the diffusion experiments (through-diffusion, in-diffusion and reservoir depletion). K d of 137 Cs in compacted bentonite determined from the three types of diffusion experiments was in good accordance with that determined by the batch sorption experiment for dispersed bentonite. (author)

Effect of CH4 on the CO2 breakthrough pressure and permeability of partially saturated low-permeability sandstone in the Ordos Basin, China

Science.gov (United States)

Zhao, Yan; Yu, Qingchun

2018-01-01

The behavior of CO2 that coexists with CH4 and the effect of CH4 on the CO2 stream need to be deeply analyzed and studied, especially in the presence of water. Our previous studies investigated the breakthrough pressure and permeability of pure CO2 in five partially saturated low-permeability sandstone core samples from the Ordos Basin, and we concluded that rocks with a small pore size and low permeability show considerable sealing capacity even under unsaturated conditions. In this paper, we selected three of these samples for CO2-CH4 gas-mixture breakthrough experiments under various degrees of water saturation. The breakthrough experiments were performed by increasing the gas pressure step by step until breakthrough occurred. Then, the effluent gas mixture was collected for chromatographic partitioning analysis. The results indicate that CH4 significantly affects the breakthrough pressure and permeability of CO2. The presence of CH4 in the gas mixture increases the interfacial tension and, thus, the breakthrough pressure. Therefore, the injected gas mixture that contains the highest (lowest) mole fraction of CH4 results in the largest (smallest) breakthrough pressure. The permeability of the gas mixture is greater than that for pure CO2 because of CH4, and the effective permeability decreases with increased breakthrough pressure. Chromatographic partitioning of the effluent mixture gases indicates that CH4 breaks through ahead of CO2 as a result of its weaker solubility in water. Correlations are established between (1) the breakthrough pressure and water saturation, (2) the effective permeability and water saturation, (3) the breakthrough pressure and effective permeability, and (4) the mole fraction of CO2/CH4 in the effluent mixture gases and water saturation. These results deepen our understanding of the multi-phase flow behavior in the porous media under unsaturated conditions, which have implications for formulating emergency response plans for gas

Energy and Emission Characteristics of a Short-Arc Xenon Flash Lamp Under "Saturated" Optical Brightness Conditions

Science.gov (United States)

Kamrukov, A. S.; Kireev, S. G.; Kozlov, N. P.; Shashkovskii, S. G.

2017-09-01

We present the results of a study of the electrical, energy, and spectral brightness characteristics of an experimental three-electrode high-pressure xenon flash lamp under conditions ensuring close to maximum possible spectral brightness for the xenon emission. We show that under saturated optical brightness conditions (brightness temperature in the visible region of the spectrum 30,000 K), emission of a pulsed discharge in xenon is quite different from the emission from an ideal blackbody: the maximum brightness temperatures are 24,000 K in the short-wavelength UV region and 19,000 K in the near IR range. The relative fraction of UV radiation in the emission spectrum of the lamp is >50%, which lets us consider such lamps as promising broadband sources of radiation with high spectral brightness for many important practical applications.

Elastoplastic model for unsaturated, quasi-saturated and fully saturated fine soils

Directory of Open Access Journals (Sweden)

Lai Ba Tien

2016-01-01

Full Text Available In unsaturated soils, the gaseous phase is commonly assumed to be continuous. This assumption is no more valid at high saturation ratio. In that case, air bubbles and pockets can be trapped in the porous network by the liquid phase and the gas phase becomes discontinuous. This trapped air reduces the apparent compressibility of the pore fluid and affect the mechanical behavior of the soil. Although it is trapped in the pores, its dissolution can take place. Dissolved air can migrate through the pore space, either by following the flow of the fluid or by diffusion. In this context, this paper present a hydro mechanical model that separately considers the kinematics and the mechanical behavior of each fluid species (eg liquid water, dissolved air, gaseous air and the solid matrix. This new model was implemented in a C++ code. Some numerical simulations are performed to demonstrate the ability of this model to reproduce a continuous transition of unsaturated to saturated states.

Measurement of dissolved Cs-137 in stream water, soil water and groundwater at Headwater Forested Catchment in Fukushima after Fukushima Dai-ichi Nuclear Power Plant Accident

Science.gov (United States)

Iwagami, Sho; Tsujimura, Maki; Onda, Yuichi; Sakakibara, Koichi; Konuma, Ryohei; Sato, Yutaro

2016-04-01

Radiocesium migration from headwater forested catchment is important perception as output from the forest which is also input to the subsequent various land use and downstream rivers after Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. In this study, dissolved Cs-137 concentration of stream water, soil water and groundwater were measured. Observations were conducted at headwater catchment in Yamakiya district, located 35 km northwest of FDNPP from April 2014 to November 2015. Stream water discharge was monitored and stream water samples were taken at main channel and sub channel. Stream water discharge was monitored by combination of parshallflume and v-notch weir. Stream water was sampled manually at steady state condition in 3-4 month interval and also intense few hours interval sampling were conducted during rainfall events using automated water sampler. Around the sub channel, it is found that there is a regularly saturated area at the bottom of the slope, temporary saturated area which saturate during the rainy season in summer and regularly dry area. 6 interval cameras were installed to monitor the changing situation of saturated area. Suction lysimeters were installed at three areas (regularly saturated area, temporary saturated area and dry area) for sampling soil water in depth of 0.1 m and 0.3 m. Boreholes were installed at three points along the sub channel. Three boreholes with depth of 3 m, 5 m and 10 m were installed at temporary saturated area, 20 m upstream of sub channel weir. Another three boreholes with depth of 3 m, 5 m and 10 m were installed at dry area, 40 m upstream of sub channel weir. And a borehole with depth of 20 m was installed at ridge of sub catchment, 52 m upstream of sub channel weir. Groundwater was sampled by electrically powered pump and groundwater level was monitored. Also suction-free lysimeter was installed at temporary saturated area for sampling the near surface subsurface water. Soil water samples were collected

Chlorine-containing salts as water ice nucleating particles on Mars

Science.gov (United States)

Santiago-Materese, D. L.; Iraci, L. T.; Clapham, M. E.; Chuang, P. Y.

2018-03-01

Water ice cloud formation on Mars largely is expected to occur on the most efficient ice nucleating particle available. Salts have been observed on the Martian surface and have been known to facilitate water cloud formation on Earth. We examined heterogeneous ice nucleation onto sodium chloride and sodium perchlorate substrates under Martian atmospheric conditions, in the range of 150 to 180 K and 10-7 to 10-5 Torr water partial pressure. Sub-155 K data for the critical saturation ratio (Scrit) suggests an exponential model best describes the temperature-dependence of nucleation onset of water ice for all substrates tested. While sodium chloride does not facilitate water ice nucleation more easily than bare silicon, sodium perchlorate does support depositional nucleation at lower saturation levels than other substrates shown and is comparable to smectite-rich clay in its ability to support cloud initiation. Perchlorates could nucleate water ice at partial pressures up to 40% lower than other substrates examined to date under Martian atmospheric conditions. These findings suggest air masses on Mars containing uplifted salts such as perchlorates could form water ice clouds at lower saturation ratios than in air masses absent similar particles.

Two-phase flows during draining of liquefied gases initially undersaturated. Validation by water and CFC11; Ecoulements diphasiques lors de la vidange de gaz liquifies initialement sous satures. Validation par l`eau et le CFC11

Energy Technology Data Exchange (ETDEWEB)

May, L.

1996-12-11

In petroleum industry, the safety studies require to estimate the two-phase flow during accidental draining of pressurized liquefied gas storages. Meanwhile the mass flow strongly depends of initial conditions. Then it is primordial to be able to reckon it in the case where it is the highest, that is to say when the fluid is initially undersaturated. An experimental installation has been carried out. The used fluids are water and CFC11. The experimental measures show that the thermodynamic conditions at the inlet of the pipe (P at +/- 15 mbar and T at +/- 0.15 degrees Celsius) are well controlled. The measured mass flows are compared to different models. The frictions in the monophase domain have been taken into account. It has been shown that the extensive H.E.M. model perfectly estimates the mass flow (as well as for water than for CFC11) for large deviations to saturation. In order to correctly predict the domain of weak variation to saturation, D.E.M. (out of equilibrium) models or H.R.M. (homogeneous model of relaxation) models have to be used. (O.M.) 50 refs.

SATCAP-B: a program for thermal-hydraulic design of 'Saturated Temperature Capsule'

International Nuclear Information System (INIS)

Harayama, Yasuo; Someya, Hiroyuki; Niimi, Motoji

1989-11-01

As an advanced irradiation technique, the JMTR (Japan Materials Testing Reactor) project is developing a 'Saturated Temperature Capsule' which water is injected in and boiled. When the water is kept at a constant pressure, the water temperature does not become higher than the saturated temperature. This type capsule is based on the conception of keeping the coolant to the saturated temperature and using the temperature control. In designing the capsule in which the inner coolant is injected, thermal performances have to be understood as exactly as possible. Then, a program (named SATCAP) was compiled to graps the thermal performance within the capsule. On the other hand, a 'Saturated Temperature Capsule' was made and irradiated in the JMTR core. It was indicated from supplied water temperatures recorded by thermo-couples attached in the capsule that heat transfer coefficients prefered models due to natural convection to models incorporated in the initial version of the program. Then, the program was revised by adding mainly heat transfer model based on natural convection. The present report describes the calculation procedure and guides of input and output for the revised program (SATCAP version-B). (author)

Characterization of thermal, hydraulic, and gas diffusion properties in variably saturated sand grades

DEFF Research Database (Denmark)

Deepagoda Thuduwe Kankanamge Kelum, Chamindu; Smits, Kathleen; Ramirez, Jamie

2016-01-01

porous media transport properties, key transport parameters such as thermal conductivity and gas diffusivity are particularly important to describe temperature-induced heat transport and diffusion-controlled gas transport processes, respectively. Despite many experimental and numerical studies focusing...... transport models (thermal conductivity, saturated hydraulic conductivity, and gas diffusivity). An existing thermal conductivity model was improved to describe the distinct three-region behavior in observed thermal conductivity–water saturation relations. Applying widely used parametric models for saturated......Detailed characterization of partially saturated porous media is important for understanding and predicting vadose zone transport processes. While basic properties (e.g., particle- and pore-size distributions and soil-water retention) are, in general, essential prerequisites for characterizing most...

Field test facility for monitoring water/radionuclide transport through partially saturated geologic media: design, construction, and preliminary description. Appendix I. Engineering drawings

International Nuclear Information System (INIS)

Phillips, S.J.; Campbell, A.C.; Campbell, M.D.; Gee, G.W.; Hoober, H.H.; Schwarzmiller, K.O.

1979-11-01

The engineering plans for a test facility to monitor radionuclide transport in water through partially saturated geological media are included. Drawings for the experimental set-up excavation plan and details, lysimeter, pad, access caisson, and caisson details are presented

HAM solutions on MHD squeezing axisymmetric flow of water nanofluid through saturated porous medium between two parallel disks

Science.gov (United States)

Reddy, B. Siva Kumar; Rao, K. V. Surya Narayana; Vijaya, R. Bhuvana

2017-07-01

In this paper, we have considered the unsteady magnetohydrodynamic squeezing axi-symmetric flow of water-nanofluid through saturated porous medium between two parallel disks. The equations for the governing flow are solved by Galerkin optimal Homotopy asymptotic method. The effects of non-dimensional parameters on velocity, temperature and concentration have been discussed with the help of graphs. Also we obtained local Nusselt number and computationally discussed with reference to flow parameters.

A condition for the overflow stability of second-order digital filters that is satisfied by all scaled state-space structures using saturation

NARCIS (Netherlands)

Ritzerfeld, J.H.F.

1989-01-01

A set of conditions is derived that ensures overflow stability of second-order digital filters for different classes of overflow arithmetics, involving only the elements of the state-transition matrix. The well-known arithmetic saturation, zeroing, and two's-complement lead to different stability

Gas and Water Permeability of Concrete

Energy Technology Data Exchange (ETDEWEB)

Villar, M. V.; Martin, P. L.; Romero, F. J.; Gutierrez-Rodirgo, V.; Barcala, J. M.

2012-11-01

The gas pressure of concrete samples was measured in an unsteady-state equipment working under low injection pressures and in a newly fine tuned steady-state setup working under different pressures. These measurements allowed the estimation of the intrinsic and relative gas permeability of the concrete and of the effect of boundary conditions on them. Permeability decreased with water content, but it was also greatly affected by the hydraulic history of concrete, i.e. if it had been previously dried or wetted. In particular, and for a given degree of saturation, the gas permeability of concrete previously saturated was lower than if the concrete had been just air dried or saturated after air drying. In any case, the gas permeability was about two orders of magnitude higher than the liquid water permeability (10-16 vs. 10-18 m2), probably due to the chemical reactions taking place during saturation (carbonation). The relative gas permeability of concrete increased sharply for water degrees of saturation smaller than 50%. The boundary conditions also affected the gas permeability, which seemed to be mostly conditioned by the back pressure and the confining pressure, increasing as the former increased and decreasing as the latter increased, i.e. decreasing as the effective pressure increased. Overall the increase of pressure head or injection pressure implied a decrease in gas permeability. External,microcracking during air-drying could not be ruled out as responsible for the decrease of permeability with confining pressure. The apparent permeability obtained applying the Klinkenberg method for a given effective pressure was only slightly smaller than the average of all the values measured for the same confining pressure range. For this reason it is considered that the Klinkenberg effect was not relevant in the range of pressures applied. (Author) 37 refs.

A solution thermodynamics definition of the fiber saturation point and the derivation of a wood-water phase (state) diagram

Science.gov (United States)

Samuel L. Zelinka; Samuel V. Glass; Joseph E. Jakes; Donald S. Stone

2016-01-01

The fiber saturation point (FSP) is an important concept in wood– moisture relations that differentiates between the states of water in wood and has been discussed in the literature for over 100 years. Despite its importance and extensive study, the exact theoretical definition of the FSP and the operational definition (the correct way to measure the FSP) are still...

Saturated Zone Colloid-Facilitated Transport

International Nuclear Information System (INIS)

Wolfsberg, A.; Reimus, P.

2001-01-01

The purpose of the Saturated Zone Colloid-Facilitated Transport Analysis and Modeling Report (AMR), as outlined in its Work Direction and Planning Document (CRWMS MandO 1999a), is to provide retardation factors for colloids with irreversibly-attached radionuclides, such as plutonium, in the saturated zone (SZ) between their point of entrance from the unsaturated zone (UZ) and downgradient compliance points. Although it is not exclusive to any particular radionuclide release scenario, this AMR especially addresses those scenarios pertaining to evidence from waste degradation experiments, which indicate that plutonium and perhaps other radionuclides may be irreversibly attached to colloids. This report establishes the requirements and elements of the design of a methodology for calculating colloid transport in the saturated zone at Yucca Mountain. In previous Total Systems Performance Assessment (TSPA) analyses, radionuclide-bearing colloids were assumed to be unretarded in their migration. Field experiments in fractured tuff at Yucca Mountain and in porous media at other sites indicate that colloids may, in fact, experience retardation relative to the mean pore-water velocity, suggesting that contaminants associated with colloids should also experience some retardation. Therefore, this analysis incorporates field data where available and a theoretical framework when site-specific data are not available for estimating plausible ranges of retardation factors in both saturated fractured tuff and saturated alluvium. The distribution of retardation factors for tuff and alluvium are developed in a form consistent with the Performance Assessment (PA) analysis framework for simulating radionuclide transport in the saturated zone. To improve on the work performed so far for the saturated-zone flow and transport modeling, concerted effort has been made in quantifying colloid retardation factors in both fractured tuff and alluvium. The fractured tuff analysis used recent data

Forest decline caused by high soil water conditions in a permafrost region

Directory of Open Access Journals (Sweden)

H. Iwasaki

2010-02-01

Full Text Available In the permafrost region near Yakutsk, eastern Siberia, Russia, annual precipitation (June–May in 2005–2006 and 2006–2007 exceeded the 26-year (1982–2008 mean of 222±68 mm by 185 mm and 128 mm, respectively, whereas in 2007–2008 the excedent was only 48 mm, well within the range of variability. Yellowing and browning of larch (Larix cajanderi Mayr. trees occurred in an undisturbed forest near Yakutsk in the 2007 summer growing season. Soil water content at a depth of 0.20 m was measured along a roughly 400 m long line transect running through areas of yellowing and browning larch trees (YBL and of normal larch trees (NL. In the two years of supranormal precipitation, soil water content was very high compared to values recorded for the same area in previous studies. For both wet years, the mean degree of saturation (s was significantly greater in YBL than NL areas, whereas the converse was the case for the gas diffusivity in soil. This implies that rather than mitigating water stress suffered during normal precipitation years, elevated soil water conditions adversely affected the growth of larch trees. Eastern Siberia's taiga forest extends widely into the permafrost region. Was such supranormal annual precipitation to extend for more than two years, as might be expected under impending global climate changes, forest recovery may not be expected and emission of greenhouse gas might continue in future.

Nonlinear feedback control of chaotic pendulum in presence of saturation effect

Energy Technology Data Exchange (ETDEWEB)

Alasty, Aria [Center of Excellence in Design, Robotics, and Automation (CEDRA), Department of Mechanical Engineering, Sharif University of Technology, Azadi Avenue, Tehran 1458889694 (Iran, Islamic Republic of)]. E-mail: aalasti@sharif.edu; Salarieh, Hassan [Center of Excellence in Design, Robotics, and Automation (CEDRA), Department of Mechanical Engineering, Sharif University of Technology, Azadi Avenue, Tehran 1458889694 (Iran, Islamic Republic of)]. E-mail: salarieh@mehr.sharif.edu

2007-01-15

In present paper, a feedback linearization control is applied to control a chaotic pendulum system. Tracking the desired periodic orbits such as period-one, period-two, and period-four orbits is efficiently achieved. Due to the presence of saturation in real world control signals, the stability of controller is investigated in presence of saturation and sufficient stability conditions are obtained. At first feedback linearization control law is designed, then to avoid the singularity condition, a saturating constraint is applied to the control signal. The stability conditions are obtained analytically. These conditions must be investigated for each specific case numerically. Simulation results show the effectiveness and robustness of proposed controller. A major advantage of this method is its shorter chaotic transient time in compare to other methods such as OGY and Pyragas controllers.

Relative Humidity in the Tropopause Saturation Layer

Science.gov (United States)

Selkirk, H. B.; Schoeberl, M. R.; Pfister, L.; Thornberry, T. D.; Bui, T. V.

2017-12-01

The tropical tropopause separates two very different atmospheric regimes: the stable lower stratosphere where the air is both extremely dry and nearly always so, and a transition layer in the uppermost tropical troposphere, where humidity on average increases rapidly downward but can undergo substantial temporal fluctuations. The processes that control the humidity in this layer below the tropopause include convective detrainment (which can result in either a net hydration or dehydration), slow ascent, wave motions and advection. Together these determine the humidity of the air that eventually passes through the tropopause and into the stratosphere, and we refer to this layer as the tropopause saturation layer or TSL. We know from in situ water vapor observations such as Ticosonde's 12-year balloonsonde record at Costa Rica that layers of supersaturation are frequently observed in the TSL. While their frequency is greatest during the local rainy season from June through October, supersaturation is also observed in the boreal winter dry season when deep convection is well south of Costa Rica. In other words, local convection is not a necessary condition for the presence of supersaturation. Furthermore, there are indications from airborne measurements during the recent POSIDON campaign at Guam that if anything deep convection tends to `reset' the TSL locally to a state of just-saturation. Conversely, it may be that layers of supersaturation are the result of slow ascent. To explore these ideas we take Ticosonde water vapor observations from the TSL, stratify them on the basis of relative humidity and report on the differences in the the history of upstream convective influence between supersaturated parcels and those that are not.

Simulation of KAEVER experiments on aerosol behavior in a nuclear power plant containment at accident conditions with the ASTEC code

International Nuclear Information System (INIS)

Kljenak, I.; Mavko, B.

2006-01-01

Experiments on aerosol behaviour in saturated and non-saturated atmosphere, which were performed in the KAEVER experimental facility, were simulated with the severe accident computer code ASTEC CPA V1.2. The specific purpose of the work was to assess the capability of the code to model aerosol condensation and deposition in the containment of a light-water-reactor nuclear power plant at severe accident conditions, if the atmosphere saturation conditions are simulated adequately. Five different tests were first simulated with boundary conditions, obtained from the experiments. In all five tests, a non-saturated atmosphere was simulated, although, in four tests, the atmosphere was allegedly saturated. The simulations were repeated with modified boundary conditions, to obtain a saturated atmosphere in all tests. Results of dry and wet aerosol concentrations in the test vessel atmosphere for both sets of simulations are compared to experimental results. (author)

A Partially Saturated Constitutive Theory for Compacted Fills

National Research Council Canada - National Science Library

Berney, Ernest

2004-01-01

... variables present within the soil. From a thermodynamic viewpoint, a partially saturated soil can be best described by the free energy associated with each component of the soil and water mixture...

Déplacements polyphasiques en milieu poreux. Injection de vapeur en conditions adiabatiques Multiphase Displacements in Porous Media. Steam Flooding under Adiabatic Conditions

Directory of Open Access Journals (Sweden)

Koci X.

2006-11-01

that no heating collars are necessary. The experimental device shown in Figs. 1 and 2 can work under either isothermal or adiabatic conditions. It is designed to operate up to 250°C and 20 bar. The residual oil saturations after steam injection are calculated from the mass balance. Some of these results are shown in Table 1. The parameters modified were the injection flow rate (between 2 and 5 g/min. and the absolute pressure at the inlet of the porous medium (between 4 and 7 bar. Figures 3 to 6 correspond to an experiment performed under the following conditions :(a Initial condition: irreducible water saturation. (b Injection flow rate = 2 g/min. (c Injection temperature = 220°C. (d Absolute pressure at outlet = 3 bar. (e The injected steam was slightly overheated (this allows to know what is really injected and, due to the rather low enthalpy added compared to the enthalpy of saturated steam, this does not have any significant influence on the heat balance and therefore on the displacement. This experiment shows a very clearcut steam front moving all along the tube. The entire displacement occurs under conditions corresponding to vaporization/condensation equilibrium of steam (Table 2. Experiments were modeled by the TSAR (Thermal Simulator Applied to Reservoir simulator for thermal methods developed at IFP [2]. This 3-D model can be used to either simulate field processes or laboratory experiments. Relative permeabilities in function of saturations and temperatures obtained from previous isothermal experiments [1] were used in the simulator. Three-phase permeabilities were computed by the Stone method [4 to 6]. For computing, the following assumptions were made :(a The porous medium is considered to be as homogeneous and isotropic. (b There is no interaction between fluids and the mineral phase. (c Steam is considered to be a perfect gas. (d Steam is injected at a constant weight rate. (e Contact time between phases is long enough to assume that local

Graphene Oxide Affects Mobility and Antibacterial Ability of Levofloxacin and Ciprofloxacin in Saturated and Unsaturated Porous Media

Science.gov (United States)

Kaixuan, S.

2017-12-01

Understand the fate and impact of fluoroquinolone antibiotics (FQs) in soil and groundwater systems is critical to the safety of ecosystem and public health. In this work, laboratory batch sorption, column transport, and bacterial growth experiments were conducted to improve current understanding of the interactions between two typical FQs (levofloxacin (LEV) and ciprofloxacin (CIP)) and graphene oxide (GO) in quartz sand media under various conditions. Studies showed that both GO and quartz sand adsorbed LEV and CIP in aqueous solutions and sand was capable to compete with GO for the antibiotics. While GO showed much larger sorption capacity, the sand had stronger sorption affinity to the two antibiotics. As a result, neither LEV nor CIP showed any signs of breakthrough in saturated or unsaturated porous media. When the two antibiotics were premixed with GO, their mobility in porous media increased for both saturate and unsaturated conditions and the amount of LEV or CIP in the effluents increased with the increasing of initial GO concentration. During their transport in saturated porous media, some of the GO-bound antibiotics, especially those sorbed via relatively weak interactions, transferred from GO to the quartz sand. Under unsaturated conditions, GO-bound LEV might also transfer from GO to the air-water interface due to the strong affiliation between LEV and air-water interface. Sorption onto GO reduced the antibacterial ability of LEV and CIP, however, the GO-bound antibiotics still effectively inhibited the growth of E coli. Findings from this work indicated that mobile GO affected not only the mobility but also the ecotoxicity of LEV and CIP in porous media.

Thermophysical properties of a fluid-saturated sandstone

International Nuclear Information System (INIS)

Abid, Muhammad; Hammerschmidt, Ulf; Koehler, Juergen

2014-01-01

Thermophysical properties of a fluid-saturated stone are presented that are obtained by using the transient hot-bridge technique (THB) at ambient conditions. Measurements are succeedingly done each after having filled the porous stone structure first with six different fluids of distinct thermal conductivities and next with six different gases also having different thermal conductivities. Variations in thermal conductivity, thermal diffusivity and volumetric specific heat due to liquid or gas saturations are discussed. Internal pore structure of the stone is studied by using Scanning Electron Microscopy (SEM), Mercury Intrusion Porosimetry (MIP) and other standardized density methods at ambient conditions. Effect of interstitial pore pressure on thermophysical properties are also discussed in the context of Knudsen effect. (authors)

Behavior of uranium under conditions of interaction of rocks and ores with subsurface water

Science.gov (United States)

Omel'Yanenko, B. I.; Petrov, V. A.; Poluektov, V. V.

2007-10-01

The behavior of uranium during interaction of subsurface water with crystalline rocks and uranium ores is considered in connection with the problem of safe underground insulation of spent nuclear fuel (SNF). Since subsurface water interacts with crystalline rocks formed at a high temperature, the mineral composition of these rocks and uranium species therein are thermodynamically unstable. Therefore, reactions directed toward the establishment of equilibrium proceed in the water-rock system. At great depths that are characterized by hindered water exchange, where subsurface water acquires near-neutral and reducing properties, the interaction is extremely sluggish and is expressed in the formation of micro- and nanoparticles of secondary minerals. Under such conditions, the slow diffusion redistribution of uranium with enrichment in absorbed forms relative to all other uranium species is realized as well. The products of secondary alteration of Fe- and Ti-bearing minerals serve as the main sorbents of uranium. The rate of alteration of minerals and conversion of uranium species into absorbed forms is slow, and the results of these processes are insignificant, so that the rocks and uranium species therein may be regarded as unaltered. Under reducing conditions, subsurface water is always saturated with uranium. Whether water interacts with rock or uranium ore, the equilibrium uranium concentration in water is only ≤10-8 mol/l. Uraninite ore under such conditions always remains stable irrespective of its age. The stability conditions of uranium ore are quite suitable for safe insulation of SNF, which consists of 95% uraninite (UO2) and is a confinement matrix for all other radionuclides. The disposal of SNF in massifs of crystalline rocks at depths below 500 m, where reducing conditions are predominant, is a reliable guarantee of high SNF stability. Under oxidizing conditions of the upper hydrodynamic zone, the rate of interaction of rocks with subsurface water

Sulfur Concentration at Sulfide Saturation in Anhydrous Silicate Melts at Crustal Conditions

Science.gov (United States)

Liu, Y.; Samaha, N.; Baker, D. R.

2006-05-01

The sulfur concentration in silicate melts at sulfide saturation (SCSS) was experimentally investigated in a temperature range from 1250°C to 1450°C and a pressure range from 500 MPa to 1 GPa in a piston-cylinder apparatus. The investigated melt compositions varied from rhyolitic to basaltic. All experiments were saturated with a FeS melt. Temperature was confirmed to have a positive effect on the SCSS and no measurable pressure effect was observed. Oxygen fugacity was controlled to be either near the carbon-carbon monoxide buffer or one log unit above the nickel-nickel oxide buffer, and found to positively affect the SCSS. A series of models were constructed to predict the SCSS as a function of temperature, pressure, melt composition, oxygen fugacity and sulfur fugacity of the system. The coefficients were obtained by the regression of experimental data from this study and from data in the literature. The best model found for the prediction of the SCSS is: ln S (ppm) = 996/T + 9.875 + 0.997 ln MFM + 0.1901 ln fO2 - 0.0722 (P/T) -0.115 ln f S2, where P is in bar, T is in K, and MFM is a compositional parameter describing the melt based upon cation mole fractions: MFM = [Na + K + 2 (Ca + Mg+ Fe2+)]/[Si × (Al + Fe3+)]. This model predicts the SCSS in anhydrous silicate melts from rhyolitic to basaltic compositions at crustal conditions from 1 bar to 1.25 GPa, temperatures from ~1200 to 1400 C, and oxygen fugacities between approximately two log units below the fayalite-quartz-magnetite buffer and one log unit above the nickel-nickel oxide buffer. For cases where the oxygen and sulfur fugacities can not be adequately estimated a simpler model also works acceptably: ln S (ppm) = -5328/T + 8.431 + 1.244 ln MFM - 0.01704(P/T) + ln aFeS, where aFeS is the activity of FeS in the sulfide melt and is well approximated by a value of 1. Additional experiments were performed on other basalts in a temperature range from 1250 C to 1450 C at 1 GPa to test the models. The model

Calibration of a neutron log in partially saturated media. Part II. Error analysis

International Nuclear Information System (INIS)

Hearst, J.R.; Kasameyer, P.W.; Dreiling, L.A.

1981-01-01

Four sources or error (uncertainty) are studied in water content obtained from neutron logs calibrated in partially saturated media for holes up to 3 m. For this calibration a special facility was built and an algorithm for a commercial epithermal neutron log was developed that obtains water content from count rate, bulk density, and gap between the neutron sonde and the borehole wall. The algorithm contained errors due to the calibration and lack of fit, while the field measurements included uncertainties in the count rate (caused by statistics and a short time constant), gap, and density. There can be inhomogeneity in the material surrounding the borehole. Under normal field conditions the hole-size-corrected water content obtained from such neutron logs can have an uncertainty as large as 15% of its value

Map showing thickness of saturated Quaternary deposits, Sugar House quadrangle, Salt Lake County, Utah, February 1972

Science.gov (United States)

Mower, R.W.

1973-01-01

Saturated Quaternary deposits in the Sugar Horse quadrangle supply significant quantities of water to wells from which water is withdrawn for domestic, municipal, industrial, and irrigation uses. The deposits consist of clay, silt, sand, and gravel; individual beds range from a few inches to several tens of feet thick. The principal aquifer, which is almost completely within the Quaternary deposits, supplied about 4 percent, or 9,000 acre-feet, of the municipal and industrial water used annually in Salt Lake County during 1964-68.As a general rule, more water is stored and more water will be yielded to a well where aquifers are thicker. This map can be used as a general guide to those areas where greatest amounts of water are stored in the aquifer, and where yields to wells may be greater. Local variations in the ability of saturated deposits to transmit water can alter the general relationship between aquifer thickness and yield of wells.The thickness of saturated Quaternary deposits within the area of the Sugar Horse quadrangle ranges from zero to about 650 feet, as shown on the map. The thickest section of these deposits is near the southwestern corner of the quadrangle, and the thinnest section is along the mountain front adjacent to the approximate eastern limit of saturated Quaternary deposits.The thickness of saturated Quaternary deposits shown on this map is based on drillers’ logs for 55 deep wells (which show the thickness of the Quaternary deposits) and on water-level measurements made in February 1972 in wells in unconfined shallow aquifers.Reports in the following list of selected references contain other information about the saturated Quaternary deposits in this and adjacent parts of Jordan Valley, Utah. The basic-data reports and releases contain well logs, water-level measurements, and other types of basic ground-water data. The interpretive repots contain discussions of the occurrence of ground water, tests to determine hydraulic properties of

Radiation-induced polymerization of water-saturated styrene in a wide range of dose rate

International Nuclear Information System (INIS)

Takezaki, J.; Okada, T.; Sakurada, I.

1978-01-01

Radiation-induced polymerization of water-saturated styrene (water content 3.5 x 10 -2 mole/liter) was carried out in a wide range of dose rate between 1.2 x 10 3 and 1.8 x 10 7 rad/sec, and compared with the polymerization of the moderately dried styrene (water content 3.2 x 10 -3 mole/liter). Molecular weight distribution curves of the polymerization products showed that they were generally consisted of four parts, namely, oligomers, radical, cationic, and super polymers. Contributions of the four constituents to the polymerization and the number average degrees of polymerization (DP) of the four kinds of polymers were calculated by the graphical analysis of the curves. The rate of radical polymerization and DP of radical polymers are independent of the water content; the dose rate dependences of the polymerization rate and DP agree with the well known square root and inverse square root laws, respectively, of the radical polymerization of styrene. The rate of ionic polymerization is directly proportional to the dose rate, but it decreases, at a given dose rate, inversely proportional to the water content of styrene. DP of ionic polymer is independent of the dose rate but decreases with increasing water content. The super polymer of DP about 10 4 is not formed in the case of the moderately dried styrene. G values for the initiating radical and ion formation are calculated to be independently of the dose rate and water content, 0.66 and 0.027, respectively. It was suggested that oligomer was formed in the early stage by the interaction of cation with anion and only those cations which had survived underwent polymerization. 10 figures, 4 tables

Kinetics of carbonate dissolution in CO2-saturated aqueous system at reservoir conditions

Science.gov (United States)

Peng, Cheng; Crawshaw, John P.; Maitland, Geoffrey; Trusler, J. P. Martin

2014-05-01

In recent years, carbon capture and storage (CCS) has emerged as a key technology for limiting anthropogenic CO2 emissions while allowing the continued utilisation of fossil fuels. The most promising geological storage sites are deep saline aquifers because the capacity, integrity and injection economics are most favourable, and the environmental impact can be minimal. Many rock-fluid chemical reactions are known to occur both during and after CO2 injection in saline aquifers. The importance of rock-fluid reactions in the (CO2 + H2O) system can be understood in terms of their impact on the integrity and stability of both the formation rocks and cap rocks. The chemical interactions between CO2-acidified brines and the reservoir minerals can influence the porosity and permeability of the formations, resulting in changes in the transport processes occurring during CO2 storage. Since carbonate minerals are abundant in sedimentary rocks, one of the requirements to safely implement CO2 storage in saline aquifers is to characterise the reactivity of carbonate minerals in aqueous solutions at reservoir conditions. In this work, we reported measurements of the intrinsic rate of carbonate dissolution in CO2-saturated water under high-temperature high-pressure reservoir conditions extending up to 373 K and 14 MPa. The rate of carbonate dissolution in CO2-free HCl(aq) was also measured at ambient pressure at temperatures up to 353 K. Various pure minerals and reservoir rocks were investigated in this study, including single-crystals of calcite and magnesite, and samples of dolomite, chalks and sandstones. A specially-designed batch reactor system, implementing the rotating disc technique, was used to obtain the intrinsic reaction rate at the solid/liquid interface, free of mass transfer effects. The effective area and mineralogy of the exposed surface was determined by a combination of surface characterisation techniques including XRD, SEM, EDX and optical microscopy. The

Development of synchronous generator saturation model from steady-state operating data

Energy Technology Data Exchange (ETDEWEB)

Jadric, Martin; Despalatovic, Marin; Terzic, Bozo [FESB University of Split, Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, Split (Croatia)

2010-11-15

A new method to estimate and model the saturated synchronous reactances of hydroturbine generators from operating data is presented. For the estimation process, measurements of only the generator steady-state variables are required. First, using a specific procedure, the field to armature turns ratio is estimated from measured steady-state variables at constant power generation and various excitation conditions. Subsequently, for each set of steady-state operating data, saturated synchronous reactances are identified. Fitting surfaces, defined as polynomial functions in two variables, are later used to model these saturated reactances. It is shown that the simpler polynomial functions may be used to model saturation at the steady-state than at the dynamic conditions. The developed steady-state model is validated with measurements performed on the 34 MVA hydroturbine generator. (author)

Experimental Determination of Frost Resistance of Autoclaved Aerated Concrete at Different Levels of Moisture Saturation

Science.gov (United States)

Kočí, Václav; Maděra, Jiří; Jerman, Miloš; Černý, Robert

2018-06-01

The ability of porous building materials to stand up to moisture phase changes induced by alternating environment is described mostly by means of their frost resistance. However, the test conditions defined by relevant standards might not capture the real situation on building site in various locations. In particular, the prescribed full water saturation of analyzed specimens during the whole time of a freeze/thaw experiment presents an ultimate case only but certainly not an everyday reality. Even the materials of surface layers are mostly exposed to such severe conditions just for a limited period of time. In this paper, the experimental analysis of frost resistance of three different types of autoclaved aerated concrete (AAC) is performed in an extended way, including not only the standard testing but also the investigation of dry- and partially saturated samples. A complementary computational analysis of an AAC building envelope in Central European climate is presented as well, in order to illustrate the likely hygric conditions in the wall. Experimental results show that according to the standard test the loss of compressive strength, as well as the loss of mass after 25 cycles, is acceptable for all studied samples but after 50 cycles only the material with the compressive strength of 4 MPa performs satisfactorily. On the other hand, the tests with initially dried or partially saturated samples indicate a good frost resistance of all studied materials for both 25 and 50 cycles.

Thermo-hydric characterization of partially saturated porous media; Caracterisation thermo-hydrique de milieux poreux partiellement satures d'eau

Energy Technology Data Exchange (ETDEWEB)

Simon Salager; Frederic Jamin; Moulay Said El Youssoufi; Christian Saix [Laboratoire de Mecanique et Genie Civil, Universite Montpellier II, cc 048, Place Eugene Bataillon, 34095 Montpellier (France)

2005-07-01

We present a contribution to the thermo-hydric characterization of partially saturated porous media by water, through the characteristic curve. This curve defines the relation between suction and degree of saturation. Using this curve for a given temperature, a model is used to predict it for other temperatures. An experimental device called pressure cell was made in a thermo-regulated environment. The model was validated by several tests on a ceramic and silty clayey sand, at 20 and 60 C. The results obtained lead to a characteristic surface which can be considered as a generalization of the classical characteristic curve. (authors)

Shearing of saturated clays in rock joints at high confining pressures

International Nuclear Information System (INIS)

Wang, C.; Mao, N.

1979-01-01

Saturated clays are sheared between rock joints at various pore water pressures and at confining pressures up to 3 kb (300 Mpa). Sliding on these joints is stable. For a given clay, the shear stress required to initiate sliding increases linearly with the effective normal stress across the sliding surface, with a slope of 0.08 +- 0.01 for joints filled with saturated montmorillonite, 0.12 +- 0.01 with saturated chlorite, 0.15 +- 0.01 with saturated kaolinite, and 0.22 +- 0.02 with saturated silty illite. Thus at high confining pressures the shear stress required to initiate sliding on joints filled with saturated clays are very much smaller than that required to initiate sliding on clean rock joints or on joints filled with dry gouge materials. In the crust, saturation of gouge materials along active faults would greatly lower the frictional resistance to faulting and would stabilize fault movement. Different fault behaviors such as stable creep along some faults and intermittent but sudden slip along others may reflect in part different degrees of saturation of fault zones at depth

Experimental study and theoretical interpretation of saturation effect on ultrasonic velocity in tight sandstones under different pressure conditions

Science.gov (United States)

Li, Dongqing; Wei, Jianxin; Di, Bangrang; Ding, Pinbo; Huang, Shiqi; Shuai, Da

2018-03-01

Understanding the influence of lithology, porosity, permeability, pore structure, fluid content and fluid distribution on the elastic wave properties of porous rocks is of great significance for seismic exploration. However, unlike conventional sandstones, the petrophysical characteristics of tight sandstones are more complex and less understood. To address this problem, we measured ultrasonic velocity in partially saturated tight sandstones under different effective pressures. A new model is proposed, combining the Mavko-Jizba-Gurevich relations and the White model. The proposed model can satisfactorily simulate and explain the saturation dependence and pressure dependence of velocity in tight sandstones. Under low effective pressure, the relationship of P-wave velocity to saturation is pre-dominantly attributed to local (pore scale) fluid flow and inhomogeneous pore-fluid distribution (large scale). At higher effective pressure, local fluid flow gradually decreases, and P-wave velocity gradually shifts from uniform saturation towards patchy saturation. We also find that shear modulus is more sensitive to saturation at low effective pressures. The new model includes wetting ratio, an adjustable parameter that is closely related to the relationship between shear modulus and saturation.

Stability of the ammonium-p-tert-butylcalix[4]arene-tetrakis (N,N-diethylacetamide) complex in nitrobenzene saturated with water

International Nuclear Information System (INIS)

Makrlik, E.

2006-01-01

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium NH 4 + (aq)+NaL + (nb) ↔ NH 4 L + (nb)+Na + (aq) taking place in the two-phase water-nitrobenzene system (L = p-tert-butylcalix[4]arene-tetrakis (N,N-diethylacetamide); aq = aqueous phase, nb = nitrobenzene phase) was evaluated as logK ex (NH 4 + ,NaL + ) = -1.8. Further, the stability constant of the p-tert-butylcalix[4]arene-tetrakis (N,N-diethylacetamide)-ammonium complex in nitrobenzene saturated with water was calculated for a temperature of 25 deg C: logβ nb (NH 4 L + ) = 6.7. (author)

Effect of pore water pressure on P-wave velocity in water-filled sands with partial air saturation; Fukanzen howa jotai no suna shiryo wo denpasuru P ha sokudo ni oyobosu kangeki suiatsu no eikyo

Energy Technology Data Exchange (ETDEWEB)

Kanema, T [Chishitsu-Keisoku Co. Ltd., Tokyo (Japan)

1997-10-22

With an objective to elucidate change in velocity of elastic waves in association with water pressure increase in a sand bed below the groundwater level in a shallow portion of the ground, a measurement experiment was carried out on P-wave velocity in sand samples with partial air saturation. The experiment has used fine sand having an equivalent coefficient of 2.40, a soil particle density of 2.68 g/cm {sup 3} or 60%, and a grain size of 0.36 mm. Inside the water-filled sand sample, two accelerometers were embedded 20 cm apart from each other as vibration receivers. An electromagnetic hammer for P-wave was used as the vibration source. In the experiment, measurement was carried out on the P-wave velocity in association with increase in pore water pressure by applying water pressure afresh to the water-filled sample. As a result of the experiment, the following matters were disclosed: the P-wave velocity increases as the pore water pressure was increased, and a phenomenon was recognized that the dominant frequency changes into high frequency; the degree of increase in the P-wave velocity varies depending on initial saturation of the sample; and bubbles in the pore fluid have their volume decreased due to compression resulted from increased pore water pressure and dissolution of air into the pore water. 6 refs., 11 figs.

Acoustic and mechanical response of reservoir rocks under variable saturation and effective pressure.

Science.gov (United States)

Ravazzoli, C L; Santos, J E; Carcione, J M

2003-04-01

We investigate the acoustic and mechanical properties of a reservoir sandstone saturated by two immiscible hydrocarbon fluids, under different saturations and pressure conditions. The modeling of static and dynamic deformation processes in porous rocks saturated by immiscible fluids depends on many parameters such as, for instance, porosity, permeability, pore fluid, fluid saturation, fluid pressures, capillary pressure, and effective stress. We use a formulation based on an extension of Biot's theory, which allows us to compute the coefficients of the stress-strain relations and the equations of motion in terms of the properties of the single phases at the in situ conditions. The dry-rock moduli are obtained from laboratory measurements for variable confining pressures. We obtain the bulk compressibilities, the effective pressure, and the ultrasonic phase velocities and quality factors for different saturations and pore-fluid pressures ranging from normal to abnormally high values. The objective is to relate the seismic and ultrasonic velocity and attenuation to the microstructural properties and pressure conditions of the reservoir. The problem has an application in the field of seismic exploration for predicting pore-fluid pressures and saturation regimes.

Mental abilities and performance efficacy under a simulated 480 meters helium-oxygen saturation diving

Directory of Open Access Journals (Sweden)

gonglin ehou

2015-07-01

Full Text Available Stress in extreme environment severely disrupts human physiology and mental abilities. The present study investigated the cognition and performance efficacy of four divers during a simulated 480 meters helium-oxygen saturation diving. We analyzed the spatial memory, 2D/3D mental rotation functioning, grip strength, and hand-eye coordination ability in four divers during the 0 – 480 meters compression and decompression processes of the simulated diving. The results showed that except for its mild decrease on grip strength, the high atmosphere pressure condition significantly impaired the hand-eye coordination (especially at 300 meters, the reaction time and correct rate of mental rotation, as well as the spatial memory (especially as 410 meters, showing high individual variability. We conclude that the human cognition and performance efficacy are significantly affected during deep water saturation diving.

Ground-water conditions in Utah, spring of 1995

Science.gov (United States)

Allen, D.V.; Steiger, J.I.; Sory, J.D.; Garrett, R.B.; Burden, Carole B.; Danner, M.R.; Herbert, L.R.; Gerner, S.J.; Slaugh, B.A.; Swenson, R.L.; Howells, J.H.; Christiansen, H.K.; Bagley, A.D.

1995-01-01

This is the thirty-second in a series of annual reports that describe ground-water conditions in Utah. Reports in this series, published cooperatively by the U.S. Geological Survey and the Utah Department of Natural Resources, Division of Water Resources, provide data to enable interested parties to keep abreast of changing ground-water conditions.This report, like the others in the series, contains information on well construction, ground-water withdrawal from wells, water-level changes, related changes in precipitation and streamflow, and chemical quality of water. Supplementary data, such as maps showing water-level contours, are included in reports of this series only for those years or areas for which applicable data are available and are important to a discussion of changing ground-water conditions.This report includes individual discussions of selected significant areas of ground-water development in the State for calendar year 1994. Much of the reported data were collected by the U.S. Geological Survey in cooperation with the Utah Department of Natural Resources, Divisions of Water Rights and Water Resources.

3D mapping of water in oolithic limestone at atmospheric and vacuum saturation using X-ray micro-CT differential imaging

Energy Technology Data Exchange (ETDEWEB)

Boone, M.A., E-mail: marijn.boone@ugent.be [Department of Geology and Soil Science—UGCT, Ghent University, Krijgslaan 281 S8, 9000 Ghent (Belgium); Unit Sustainable Materials Management, VITO, Boerentang 200, 2400 Mol (Belgium); De Kock, T.; Bultreys, T. [Department of Geology and Soil Science—UGCT, Ghent University, Krijgslaan 281 S8, 9000 Ghent (Belgium); De Schutter, G. [Magnel Laboratory for Concrete Research, Department of Structural Engineering, Ghent University, Technologiepark-Zwijnaarde 904, 9052 Ghent (Belgium); Vontobel, P. [Spallation Neutron Source Division, Paul Scherrer Institute (PSI), 5232 Villigen (Switzerland); Van Hoorebeke, L. [Department of Physics and Astronomy—UGCT, Ghent University, Proeftuinstraat 86, 9000 Ghent (Belgium); Cnudde, V. [Department of Geology and Soil Science—UGCT, Ghent University, Krijgslaan 281 S8, 9000 Ghent (Belgium)

2014-11-15

Determining the distribution of fluids in porous sedimentary rocks is of great importance in many geological fields. However, this is not straightforward, especially in the case of complex sedimentary rocks like limestone, where a multidisciplinary approach is often needed to capture its broad, multimodal pore size distribution and complex pore geometries. This paper focuses on the porosity and fluid distribution in two varieties of Massangis limestone, a widely used natural building stone from the southeast part of the Paris basin (France). The Massangis limestone shows locally varying post-depositional alterations, resulting in different types of pore networks and very different water distributions within the limestone. Traditional techniques for characterizing the porosity and pore size distribution are compared with state-of-the-art neutron radiography and X-ray computed microtomography to visualize the distribution of water inside the limestone at different imbibition conditions. X-ray computed microtomography images have the great advantage to non-destructively visualize and analyze the pore space inside of a rock, but are often limited to the larger macropores in the rock due to resolution limitations. In this paper, differential imaging is successfully applied to the X-ray computed microtomography images to obtain sub-resolution information about fluid occupancy and to map the fluid distribution in three dimensions inside the scanned limestone samples. The detailed study of the pore space with differential imaging allows understanding the difference in the water uptake behavior of the limestone, a primary factor that affects the weathering of the rock. - Highlights: • The water distribution in a limestone was visualized in 3D with micro-CT. • Differential imaging allowed to map both macro and microporous zones in the rock. • The 3D study of the pore space clarified the difference in water uptake behavior. • Trapped air is visualized in the moldic

Hydrogen solubility in pore water of partially saturated argillites: Application to Callovo-Oxfordian clay-rock in the context of a nuclear waste geological disposal

International Nuclear Information System (INIS)

Lassin, A.; Dymitrowska, M.; Azaroual, M.

2011-01-01

In nuclear waste geological disposals, large amounts of hydrogen (H 2 ) are expected to be produced by different (bio-)geochemical processes. Depending on the pressure generated by such a process, H 2 could be produced as a gas phase and displace the neighbouring pore water. As a consequence, a water-unsaturated zone could be created around the waste and possibly affect the physical and physic-chemical properties of the disposal and the excavation disturbed zone around it. The present study is the first part of an ongoing research program aimed at evaluating the possible chemical evolution of the pore water-minerals-gas system in such a context. The goal of this study was to evaluate, in terms of thermodynamic equilibrium conditions, the geochemical disturbance of the pore water due to variations in hydrogen pressure, temperature and relative humidity. No heterogeneous reactions involving mineral phases of the clay-rock or reactive surface sites were taken into account in the thermodynamic analysis. In the case sulphate reduction reaction is allowed, geochemical modelling results indicate that the main disturbance is the increase in pH (from around 7 up to more than 10) and an important decrease in the redox potential (Eh) related to hydrogen dissolution. This occurs from relatively low H 2 partial pressures (∼1 bar and above). Then, temperature and relative humidity (expressed in terms of capillary pressure) further displace the thermodynamic equilibrium conditions, namely the pH and the aqueous speciation as well as saturation indices of mineral phases. Finally, the results suggest that the generation of hydrogen, combined with an increase in temperature (between 30 deg. C and 80 deg. C) and a decrease in relative humidity (from 100% to 30%), should increase the chemical reactivity of the pore water-rock-gas system. (authors)

Evaluation of the Seismic Characterision of Select Engineered Nanoparticles in Saturated Glass Beads

Science.gov (United States)

A laboratory testing apparatus was developed for the study of seismic body wave propagation through nanoparticles dispersed in pore fluid that is essentially saturating glass beads. First, the responses of water-saturated glass bead specimens were studied to establish baseline si...

Thermal characteristic test for saturated temperature type capsule

International Nuclear Information System (INIS)

Niimi, Motoji; Someya, Hiroyuki; Kobayashi, Toshiki; Ohuchi, Mitsuo; Harayama, Yasuo

1989-08-01

The Japan Material Testing Reactor Project is developing a new type capsule so-called 'Saturated Temperature Capsule', as a part of irradiation technique improvement program. This type capsule, in which the water is supplied and boiled, bases on the conception of keeping the coolant at the saturated temperature and facilitating the temperature setting of specimens heated by gamma-ray in reactor. However, out-pile test was planned, because there were few usable data for design and operation of the capsule into which the coolant was injected. A out-pile apparatus, simulated the capsule with electric heaters, was fabricated and experiments were carried out, to obtain data concerning design and operation for the capsule into which the water was injected. As a structure of simulated capsule, a type of downward coolant supply was adopted. The downward coolant tube type injectes the water in the bottom of capsule by tube through the upper flange. Major objects of experiences were to grasp thermal features under operation and to provide performances of capsule control equipment. Experimental results proved that the temperature of water within the capsule was easily varied by controlling supply water flow rate, and that the control equipment was operated stably and safety. (author)

Base-promoted isomerization of CF3-containing allylic alcohols to the corresponding saturated ketones under metal-free conditions

Directory of Open Access Journals (Sweden)

Yoko Hamada

2017-08-01

Full Text Available Following to the computational expectation, our previously reported intriguing 1,3-proton shift of 4,4,4-trifluorobut-2-yn-1-ols was successfully extended to the 4,4,4-trifluorobut-2-en-1-ol system under metal-free conditions to afford the corresponding saturated ketones in high to excellent chemical yields using such a convenient and easy-to-handle base as DBU at the toluene refluxing temperature, and utilization of the corresponding optically active substrates unambiguously demonstrated that this transformation proceeded in a highly stereoselective fashion.

Determination of residual oil saturation from time-lapse pulsed neutron capture logs in a large sandstone reservoir

International Nuclear Information System (INIS)

Syed, E.V.; Salaita, G.N.; McCaffery, F.G.

1991-01-01

Cased hole logging with pulsed neutron tools finds extensive use for identifying zones of water breakthrough and monitoring oil-water contacts in oil reservoirs being depleted by waterflooding or natural water drive. Results of such surveys then find direct use for planning recompletions and water shutoff treatments. Pulsed neutron capture (PNC) logs are useful for estimating water saturation changes behind casing in the presence of a constant, high-salinity environment. PNC log surveys run at different times, i.e., in a time-lapse mode, are particularly amenable to quantitative analysis. The combined use of the original open hole and PNC time-lapse log information can then provide information on remaining or residual oil saturations in a reservoir. This paper reports analyses of historical pulsed neutron capture log data to assess residual oil saturation in naturally water-swept zones for selected wells from a large sandstone reservoir in the Middle East. Quantitative determination of oil saturations was aided by PNC log information obtained from a series of tests conducted in a new well in the same field

Two-dimensional finite element solution for the simultaneous transport of water and solutes through a nonhomogeneous aquifer under transient saturated unsaturated flow conditions

International Nuclear Information System (INIS)

Gureghian, A.B.

1979-01-01

A mathematical model of ground water transport through an aquifer is presented. The solute of interest is a metal tracer or radioactive material which may undergo decay through a sorbing unconfined aquifer. The subject is developed under the following headings: flow equation, solute equation, boundary conditions, finite element formulation, element formulation, solution scheme (flow equation, solute equation), results and discussions, water movement in a ditch drained aquifer under transient state, water and solute movement in a homogeneous and unsaturated soil, transport of 226 Ra in nonhomogeneous aquifer, tailings pond lined, and tailings pond unlined. It is concluded that this mathematical model may have a wide variety of applications. The uranium milling industry may find it useful to evaluate the hydrogeological suitability of their disposal sites. It may prove suited for the design of clay disposal ponds destined to hold hazardous liquids. It may also provide a means of estimating the long-term impact of radionuclides or other pollutants on the quality of ground water. 31 references, 9 figures, 3 tables

TOURGHREACT: A Simulation Program for Non-isothermal Multiphase Reactive Geochemical Transport in Variably Saturated Geologic Media

OpenAIRE

Xu, Tianfu; Sonnenthal, Eric; Spycher, Nicolas; Pruess, Karsten

2004-01-01

TOUGHREACT is a numerical simulation program for chemically reactive non-isothermal flows of multiphase fluids in porous and fractured media. The program was written in Fortran 77 and developed by introducing reactive geochemistry into the multiphase fluid and heat flow simulator TOUGH2. A variety of subsurface thermo-physical-chemical processes are considered under a wide range of conditions of pressure, temperature, water saturation, ionic strength, and pH and Eh. Interactions between ...

Average Soil Water Retention Curves Measured by Neutron Radiography

Energy Technology Data Exchange (ETDEWEB)

Cheng, Chu-Lin [ORNL; Perfect, Edmund [University of Tennessee, Knoxville (UTK); Kang, Misun [ORNL; Voisin, Sophie [ORNL; Bilheux, Hassina Z [ORNL; Horita, Juske [Texas Tech University (TTU); Hussey, Dan [NIST Center for Neutron Research (NCRN), Gaithersburg, MD

2011-01-01

Water retention curves are essential for understanding the hydrologic behavior of partially-saturated porous media and modeling flow transport processes within the vadose zone. In this paper we report direct measurements of the main drying and wetting branches of the average water retention function obtained using 2-dimensional neutron radiography. Flint sand columns were saturated with water and then drained under quasi-equilibrium conditions using a hanging water column setup. Digital images (2048 x 2048 pixels) of the transmitted flux of neutrons were acquired at each imposed matric potential (~10-15 matric potential values per experiment) at the NCNR BT-2 neutron imaging beam line. Volumetric water contents were calculated on a pixel by pixel basis using Beer-Lambert s law after taking into account beam hardening and geometric corrections. To remove scattering effects at high water contents the volumetric water contents were normalized (to give relative saturations) by dividing the drying and wetting sequences of images by the images obtained at saturation and satiation, respectively. The resulting pixel values were then averaged and combined with information on the imposed basal matric potentials to give average water retention curves. The average relative saturations obtained by neutron radiography showed an approximate one-to-one relationship with the average values measured volumetrically using the hanging water column setup. There were no significant differences (at p < 0.05) between the parameters of the van Genuchten equation fitted to the average neutron radiography data and those estimated from replicated hanging water column data. Our results indicate that neutron imaging is a very effective tool for quantifying the average water retention curve.

Ground-water conditions in Utah, spring of 1994

Science.gov (United States)

Allen, D.V.; Garrett, R.B.; Sory, J.D.; Burden, Carole B.; Danner, M.R.; Herbert, L.R.; Steiger, J.I.; ReMillard, M.D.; Slaugh, B.A.; Swenson, R.L.; Howells, J.H.; Christiansen, H.K.; Bagley, A.D.

1994-01-01

This is the thirty-first in a series of annual reports that describe ground-water conditions in Utah. Reports in this series, published cooperatively by the U.S. Geological Survey and the Utah Division of Water Resources, provide data to enable interested parties to keep abreast of changing ground-water conditions.This report, like the others in the series, contains information on well construction, ground-water withdrawal from wells, water-level changes, related changes in precipitation and streamflow, and chemical quality of water. Supplementary data, such as maps showing water-level contours, are included in reports of this series only for those years or areas for which applicable data are available and are important to a discussion of changing ground-water conditions.This report includes individual discussions of selected significant areas of ground-water development in the State for calendar year 1993. Water-level fluctuations and selected related data, however, are described from the spring of 1989 to the spring of 1994. Much of the data used in this report were collected by the U.S. Geological Survey in cooperation with the Divisions of Water Rights and Water Resources, Utah Department of Natural Resources.

THERMAL AND OXYGEN CONDITIONS IN CARP PONDS DURING THE SUMMER PERIOD

Directory of Open Access Journals (Sweden)

Magdalena Wiśnios

2015-11-01

Full Text Available The work presents changes of oxygen indices in carp ponds during the summer season. The basis of the research were regular water tests conducted in two ponds: Mydlniki II intended for carp farming in the second year of fish production cycle and Bocian used for carp farming in the third (final year of breeding. The temperature of pond water in July and August was optimal for development and farming of cyprinid fish and ranged from 16.6 to 30.5 °C. The lowest value of oxygen dissolved in water (6.4 mg·dm-3 was registered in Mydlniki II pond and was higher than the oxygen optimum for carp (5 mg·dm-3. Oxygen saturation in water of fish ponds exceeded the optimum upper limit value (168% on a few dates, however, it posed no lethal threat for fish. In August in Bocian pond oxygen saturation fell within the range of optimal values, creating better conditions for fish development. In the secondary pond (Mydlniki II it was found that oxygen saturation in water on 12 dates was lower than the low optimal value (96%.

Diffusion, Coulombic interactions and multicomponent ionic transport of charged species in saturated porous media

DEFF Research Database (Denmark)

Rolle, Massimo; Muniruzzaman, Muhammad

water are cross-coupled due to the effects of Coulombic interactions. Such effects are illustrated in flow-through experiments in saturated porous media. Simple strong electrolytes (i.e., salts and strong acid solutions) were selected as tracers and their transport was studied under different advection......-dominated conditions in homogeneous and heterogeneous porous media [2-3]. The model-based interpretation of the experimental results is challenging since it requires a multicomponent ionic formulation with an accurate description of local hydrodynamic dispersion and explicitly accounting for the cross-coupling...

Vertical Variability in Saturated Zone Hydrochemistry Near Yucca Mountain, Nevada

International Nuclear Information System (INIS)

G. Patterson; P. Striffler

2007-01-01

The differences in the saturated zone hydrochemistry with depth at borehole NC-EWDP-22PC reflect the addition of recharge along Fortymile Wash. The differences in water chemistry with depth at borehole NC-EWDP-19PB appear to indicate that other processes are involved. Water from the lower part of NC-EWDP-19PB possesses chemical characteristics that clearly indicate that it has undergone cation exchange that resulted in the removal of calcium and magnesium and the addition of sodium. This water is very similar to water from the Western Yucca Mountain facies that has previously been thought to flow west of NC-EWDP-19PB. Water from the lower zone in NC-EWDP-19PB also could represent water from the Eastern Yucca Mountain facies that has moved through clay-bearing or zeolitized aquifer material resulting in the altered chemistry. Water chemistry from the upper part of the saturated zone at NC-EWDP-19PB, both zones at NC-EWDP-22PC, and wells in the Fortymile Wash facies appears to be the result of recharge through the alluvium south of Yucca Mountain and within the Fortymile Wash channel

Modeling of Microstructure Evolution in Austenitic Stainless Steels Irradiated Under Light Water Reactor Conditions

International Nuclear Information System (INIS)

Gan, J.; Stoller, R.E.; Was, G.S.

1998-01-01

A model for the development of microstructure during irradiation in fast reactors has been adapted for light water reactor (LWR) irradiation conditions (275 approximately 325 C, up to approximately10 dpa). The original model was based on the rate-theory, and included descriptions of the evolution of both dislocation loops and cavities. The model was modified by introducing in-cascade interstitial clustering, a term to account for the dose dependence of this clustering, and mobility of interstitial clusters. The purpose of this work was to understand microstructural development under LWR irradiation with a focus on loop nucleation and saturation of loop density. It was demonstrated that in-cascade interstitial clustering dominates loop nucleation in neutron irradiation in LWRS. Furthermore it was shown that the dose dependence of in-cascade interstitial clustering is needed to account for saturation behavior as commonly observed. Both quasi-steady-state (QSS) and non-steady-state (NSS) solutions to the rate equations were obtained. The difference between QSS and NSS treatments in the calculation of defect concentration is reduced at LWR temperature when in-cascade interstitial clustering dominates loop nucleation. The mobility of interstitial clusters was also investigated and its impact on loop density is to reduce the nucleation term. The ultimate goal of this study is to combine the evolution of microstructure and microchemistry together to account for the radiation damage in austenitic stainless steels

Nighttime oxidation of surfactants at the air-water interface: effects of chain length, head group and saturation

Science.gov (United States)

Sebastiani, Federica; Campbell, Richard A.; Rastogi, Kunal; Pfrang, Christian

2018-03-01

Reactions of the key atmospheric nighttime oxidant NO3 with organic monolayers at the air-water interface are used as proxies for the ageing of organic-coated aqueous aerosols. The surfactant molecules chosen for this study are oleic acid (OA), palmitoleic acid (POA), methyl oleate (MO) and stearic acid (SA) to investigate the effects of chain length, head group and degree of unsaturation on the reaction kinetics and products formed. Fully and partially deuterated surfactants were studied using neutron reflectometry (NR) to determine the reaction kinetics of organic monolayers with NO3 at the air-water interface for the first time. Kinetic modelling allowed us to determine the rate coefficients for the oxidation of OA, POA and MO monolayers to be (2.8±0.7) × 10-8, (2.4±0.5) × 10-8and (3.3±0.6) × 10-8 cm2 molecule-1 s-1 for fitted initial desorption lifetimes of NO3 at the closely packed organic monolayers, τd, NO3, 1, of 8.1±4.0, 16±4.0 and 8.1±3.0 ns, respectively. The approximately doubled desorption lifetime found in the best fit for POA compared to OA and MO is consistent with a more accessible double bond associated with the shorter alkyl chain of POA facilitating initial NO3 attack at the double bond in a closely packed monolayer. The corresponding uptake coefficients for OA, POA and MO were found to be (2.1±0.5) × 10-3, (1.7±0.3) × 10-3 and (2.1±0.4) × 10-3, respectively. For the much slower NO3-initiated oxidation of the saturated surfactant SA we estimated a loss rate of approximately (5±1) × 10-12 cm2 molecule-1 s-1, which we consider to be an upper limit for the reactive loss, and estimated an uptake coefficient of ca. (5±1) × 10-7. Our investigations demonstrate that NO3 will contribute substantially to the processing of unsaturated surfactants at the air-water interface during nighttime given its reactivity is ca. 2 orders of magnitude higher than that of O3. Furthermore, the relative contributions of NO3 and O3 to the oxidative

Shear dilatancy and acoustic emission in dry and saturated granular materials

Science.gov (United States)

Brodsky, E. E.; Siman-Tov, S.

2017-12-01

Shearing of granular materials plays a strong role in naturally sheared systems as landslides and faults. Many works on granular flows have concentrated on dry materials, but relatively little work has been done on water saturated sands. Here we experimentally investigate dry versus saturated quartz-rich sand to understand the effect of the fluid medium on the rheology and acoustic waves emission of the sheared sand. The sand was sheared in a rotary shear rheometer under applied constant normal stress boundary at low (100 µm/s) to high (1 m/s) velocities. Mechanical, acoustic data and deformation were continuously recorded and imaged. For dry and water saturated experiments the granular volume remains constant for low shear velocities ( 10-3 m/s) and increases during shearing at higher velocities ( 1 m/s). Continuous imaging of the sheared sand show that the steady state shear band thickness is thicker during the high velocity steps. No significant change observed in the shear band thickness between dry and water saturated experiments. In contrast, the amount of dilation during water saturated experiments is about half the value measured for dry material. The measured decrease cannot be explained by shear band thickness change as such is not exist. However, the reduced dilation is supported by our acoustic measurements. In general, the event rate and acoustic event amplitudes increase with shear velocity. While isolated events are clearly detected during low velocities at higher the events overlap, resulting in a noisy signal. Although detection is better for saturated experiments, during the high velocity steps the acoustic energy measured from the signal is lower compared to that recorded for dry experiments. We suggest that the presence of fluid suppresses grain motion and particles impacts leading to mild increase in the internal pressure and therefore for the reduced dilation. In addition, the viscosity of fluids may influence the internal pressure via

Experimental investigation of virus and clay particles cotransport in partially saturated columns packed with glass beads.

Science.gov (United States)

Syngouna, Vasiliki I; Chrysikopoulos, Constantinos V

2015-02-15

Suspended clay particles in groundwater can play a significant role as carriers of viruses, because, depending on the physicochemical conditions, clay particles may facilitate or hinder the mobility of viruses. This experimental study examines the effects of clay colloids on the transport of viruses in variably saturated porous media. All cotransport experiments were conducted in both saturated and partially saturated columns packed with glass beads, using bacteriophages MS2 and ΦX174 as model viruses, and kaolinite (KGa-1b) and montmorillonite (STx-1b) as model clay colloids. The various experimental collision efficiencies were determined using the classical colloid filtration theory. The experimental data indicated that the mass recovery of viruses and clay colloids decreased as the water saturation decreased. Temporal moments of the various breakthrough concentrations collected, suggested that the presence of clays significantly influenced virus transport and irreversible deposition onto glass beads. The mass recovery of both viruses, based on total effluent virus concentrations, was shown to reduce in the presence of suspended clay particles. Furthermore, the transport of suspended virus and clay-virus particles was retarded, compared to the conservative tracer. Under unsaturated conditions both clay particles facilitated the transport of ΦX174, while hindered the transport of MS2. Moreover, the surface properties of viruses, clays and glass beads were employed for the construction of classical DLVO and capillary potential energy profiles, and the results suggested that capillary forces play a significant role on colloid retention. It was estimated that the capillary potential energy of MS2 is lower than that of ΦX174, and the capillary potential energy of KGa-1b is lower than that of STx-1b, assuming that the protrusion distance through the water film is the same for each pair of particles. Moreover, the capillary potential energy is several orders of

Advantages of paramagnetic chemical exchange saturation transfer (CEST) complexes having slow to intermediate water exchange properties as responsive MRI agents.

Science.gov (United States)

Soesbe, Todd C; Wu, Yunkou; Dean Sherry, A

2013-07-01

Paramagnetic chemical exchange saturation transfer (PARACEST) complexes are exogenous contrast agents that have great potential to further extend the functional and molecular imaging capabilities of magnetic resonance. As a result of the presence of a central paramagnetic lanthanide ion (Ln(3+) ≠ La(3+) , Gd(3+) , Lu(3+) ) within the chelate, the resonance frequencies of exchangeable protons bound to the PARACEST agent are shifted far away from the bulk water frequency. This large chemical shift, combined with an extreme sensitivity to the chemical exchange rate, make PARACEST agents ideally suited for the reporting of significant biological metrics, such as temperature, pH and the presence of metabolites. In addition, the ability to turn PARACEST agents 'off' and 'on' using a frequency-selective saturation pulse gives them a distinct advantage over Gd(3+) -based contrast agents. A current challenge for PARACEST research is the translation of the promising in vitro results into in vivo systems. This short review article first describes the basic theory behind PARACEST contrast agents, their benefits over other contrast agents and their applications to MRI. It then describes some of the recent PARACEST research results: specifically, pH measurements using water molecule exchange rate modulation, T2 exchange contrast caused by water molecule exchange, the use of ultrashort TEs (TE < 10 µs) to overcome T2 exchange line broadening and the potential application of T2 exchange as a new contrast mechanism for MRI. Copyright © 2012 John Wiley & Sons, Ltd.

Integrated enhanced bioremediation and vacuum extraction for remediation of a hydrocarbon release in response to oscillating hydrologic conditions 'Traverse Co-Bio-Vac'

International Nuclear Information System (INIS)

Korreck, W.M.; Armstrong, J.M.; Douglass, R.H.

1992-01-01

The use of enhanced in-situ biological treatment and vacuum extraction has been demonstrated to be successful in the remediation of ground water and soil contaminated with hydrocarbons. Seasonal fluctuations in the ground water causes the zone of contamination to be in the either saturated or unsaturated zone of the aquifer. In order to address these conditions, an integrated engineering design approach is being taken for the full scale remediation of an aviation of an aviation gasoline spill at the US Coast Guard Air Station at Traverse City, Township, Michigan. Enhanced aerobic biodegradation will be utilized during the periods of high water table whereby most of the contaminated interval is saturated. Carbon treated water will be utilized from the existing ground water plume. Oxygen will be injected via an oxygen generator to saturate the process stream prior to discharge to the aquifer. During low water table conditions, the same infrastructure will be utilized as a modified vacuum extraction system. The same injection wells used during the high water table would then be used during the low table condition as vapor extraction wells. The vapors will be routed to an above-ground catalytic incinerator for compound destruction. This integrated approach, entitled 'Traverse Co-Bio-Vac,' should reduce the capital costs of installing a full scale remedial system as well allowing the system to operate efficiently depending on water table conditions. The system is expected to be constructed in 1992

Water calorimetry: The heat defect

International Nuclear Information System (INIS)

Klassen, N.V.; Ross, C.K.

1997-01-01

Domen developed a sealed water calorimeter at NIST to measure absorbed dose to water from ionizing radiation. This calorimeter exhibited anomalous behavior using water saturated with gas mixtures of H 2 O 2 . Using computer simulations of the radiolysis of water, the authors show that the observed behavior can be explained if, in the gas mixtures, the amount-of-substance of H 2 and of O 2 differed significantly from 50%. The authors also report the results of simulations for other dilute aqueous solutions that are used for water calorimetry--pure water, air-saturated water, and H 2 -saturated water. The production of H 2 O 2 was measured for these aqueous solutions and compared to simulations. The results indicate that water saturated with a gas mixture containing an amount-of-substance of H 2 of 50% and of O 2 of 50% is suitable for water calorimetry if the water is stirred and is in contact with a gas space of similar volume. H 2 -saturated water does not require a gas space but O 2 contamination must be guarded against. The lack of a scavenger for OH radicals in pure water means that, depending on the water purity, some pure water might require a large priming dose to remove reactive impurities. The experimental and theoretical problems associated with air-saturated water and O 2 -saturated water in water calorimeters are discussed

Modeling Quantum Dot Nanoparticle Fate and Transport in Saturated Porous Media under Varying Flow Conditions

Science.gov (United States)

Becker, M. D.; Wang, Y.; Englehart, J.; Pennell, K. D.; Abriola, L. M.

2010-12-01

As manufactured nanomaterials become more prevalent in commercial and industrial applications, the development of mathematical models capable of predicting nanomaterial transport and retention in subsurface systems is crucial to assessing their fate and distribution in the environment. A systematic modeling approach based on a modification of clean-bed filtration theory was undertaken to elucidate mechanisms governing the transport and deposition behavior of quantum dots in saturated quartz sand as a function of grain size and flow velocity. The traditional deposition governing equation, which assumes irreversible attachment by a first-order rate (katt), was modified to include a maximum or limiting retention capacity (Smax) and first-order detachment of particles from the solid phase (kdet). Quantum dot mobility experiments were performed in columns packed with three size fractions of Ottawa sand (d50 = 125, 165, and 335 μm) at two different pore-water velocities (0.8 m/d and 7.6 m/d). The CdSe quantum dots in a CdZnS shell and polyacrylic acid coating were negatively charged (zeta potential measured ca. -35 mV) with a hydrodynamic diameter of approximately 30 nm. Fitted values of katt, Smax, and kdet were obtained for each transport and deposition experiment through the implementation of a nonlinear least-squares routine developed to fit the model to experimental breakthrough and retention data via multivariate optimization. Fitted attachment rates and retention capacities increased exponentially with decreasing grain size at both flow rates, while no discernable trend was apparent for the fitted detachment rates. Maximum retention capacity values were plotted against a normalized mass flux expression, which accounts for flow conditions and grain size. A power function fit to the data yielded a dependence that was consistent with a previous study undertaken with fullerene nanoparticles.

Energy-Efficiency Analysis of a Distributed Queuing Medium Access Control Protocol for Biomedical Wireless Sensor Networks in Saturation Conditions

Directory of Open Access Journals (Sweden)

Christos Verikoukis

2011-01-01

Full Text Available The aging population and the high quality of life expectations in our society lead to the need of more efficient and affordable healthcare solutions. For this reason, this paper aims for the optimization of Medium Access Control (MAC protocols for biomedical wireless sensor networks or wireless Body Sensor Networks (BSNs. The hereby presented schemes always have in mind the efficient management of channel resources and the overall minimization of sensors’ energy consumption in order to prolong sensors’ battery life. The fact that the IEEE 802.15.4 MAC does not fully satisfy BSN requirements highlights the need for the design of new scalable MAC solutions, which guarantee low-power consumption to the maximum number of body sensors in high density areas (i.e., in saturation conditions. In order to emphasize IEEE 802.15.4 MAC limitations, this article presents a detailed overview of this de facto standard for Wireless Sensor Networks (WSNs, which serves as a link for the introduction and initial description of our here proposed Distributed Queuing (DQ MAC protocol for BSN scenarios. Within this framework, an extensive DQ MAC energy-consumption analysis in saturation conditions is presented to be able to evaluate its performance in relation to IEEE 802.5.4 MAC in highly dense BSNs. The obtained results show that the proposed scheme outperforms IEEE 802.15.4 MAC in average energy consumption per information bit, thus providing a better overall performance that scales appropriately to BSNs under high traffic conditions. These benefits are obtained by eliminating back-off periods and collisions in data packet transmissions, while minimizing the control overhead.

Determining the Threshold Value of Basil Yield Reduction and Evaluation of Water Uptake Models under Salinity Stress Condition

Directory of Open Access Journals (Sweden)

M. Sarai Tabrizi

2016-10-01

Full Text Available Introduction: Several mathematical models are being used for assessing the plant response to the salinity of the root zone. The salinity of the soil and water resources is a major challenge for agricultural sector in Iran. Several mathematical models have been developed for plant responses to the salinity stress. However, these models are often applicable in particular conditions. The objectives of this study were to evaluate the threshold value of Basil yield reduction, modeling Basil response to salinity and to evaluate the effectiveness of available mathematical models for the yield estimation of the Basil . Materials and Methods: The extensive experiments were conducted with 13 natural saline water treatments including 1.2, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.5, 4, 5, 6, 8, and 10 dSm-1. Water salinity treatments were prepared by mixing Shoor River water with fresh water. In order to quantify the salinity effect on Basil yield, seven mathematical models including Maas and Hoffman (1977, van Genuchten and Hoffman (1984, Dirksen and Augustijn (1988, and Homaee et al., (2002 were used. One of the relatively recent methods for soil water content measurements is theta probes instrument. Theta probes instrument consists of four probes with 60 mm long and 3 mm diameter, a water proof container (probe structure, and a cable that links input and output signals to the data logger display. The advantages that have been attributed to this method are high precision and direct and rapid measurements in the field and greenhouse. The range of measurements is not limited like tensiometer and is from saturation to wilting point. In this study, Theta probes instrument was calibrated by weighing method for exact irrigation scheduling. Relative transpiration was calculated using daily soil water content changes. A coarse sand layer with 2 centimeters thick was used to decrease evaporation from the surface soil of the pots. Quantity comparison of the used models was done

Saturated Switching Systems

CERN Document Server

Benzaouia, Abdellah

2012-01-01

Saturated Switching Systems treats the problem of actuator saturation, inherent in all dynamical systems by using two approaches: positive invariance in which the controller is designed to work within a region of non-saturating linear behaviour; and saturation technique which allows saturation but guarantees asymptotic stability. The results obtained are extended from the linear systems in which they were first developed to switching systems with uncertainties, 2D switching systems, switching systems with Markovian jumping and switching systems of the Takagi-Sugeno type. The text represents a thoroughly referenced distillation of results obtained in this field during the last decade. The selected tool for analysis and design of stabilizing controllers is based on multiple Lyapunov functions and linear matrix inequalities. All the results are illustrated with numerical examples and figures many of them being modelled using MATLAB®. Saturated Switching Systems will be of interest to academic researchers in con...

On the propagation of a coupled saturation and pressure front

Energy Technology Data Exchange (ETDEWEB)

Vasco, D. W.

2010-12-01

Using an asymptotic technique, valid for a medium with smoothly varying heterogeneity, I derive an expression for the velocity of a propagating, coupled saturation and pressure front. Due to the nonlinearity of the governing equations, the velocity of the propagating front depends upon the magnitude of the saturation and pressure changes across the front in addition to the properties of the medium. Thus, the expression must be evaluated in conjunction with numerical reservoir simulation. The propagation of the two-phase front is governed by the background saturation distribution, the saturation-dependent component of the fluid mobility, the porosity, the permeability, the capillary pressure function, the medium compressibility, and the ratio of the slopes of the relative permeability curves. Numerical simulation of water injection into a porous layer saturated with a nonaqueous phase liquid indicates that two modes of propagation are important. The fastest mode of propagation is a pressure-dominated disturbance that travels through the saturated layer. This is followed, much later, by a coupled mode with a large saturation change. These two modes are also observed in a simulation using a heterogeneous porous layer. A comparison between the propagation times estimated from the results of the numerical simulation and predictions from the asymptotic expression indicates overall agreement.

Pressure and fluid saturation prediction in a multicomponent reservoir, using combined seismic and electromagnetic imaging

International Nuclear Information System (INIS)

Hoversten, G.M.; Gritto, Roland; Washbourne, John; Daley, Tom

2002-01-01

This paper presents a method for combining seismic and electromagnetic measurements to predict changes in water saturation, pressure, and CO 2 gas/oil ratio in a reservoir undergoing CO 2 flood. Crosswell seismic and electromagnetic data sets taken before and during CO 2 flooding of an oil reservoir are inverted to produce crosswell images of the change in compressional velocity, shear velocity, and electrical conductivity during a CO 2 injection pilot study. A rock properties model is developed using measured log porosity, fluid saturations, pressure, temperature, bulk density, sonic velocity, and electrical conductivity. The parameters of the rock properties model are found by an L1-norm simplex minimization of predicted and observed differences in compressional velocity and density. A separate minimization, using Archie's law, provides parameters for modeling the relations between water saturation, porosity, and the electrical conductivity. The rock-properties model is used to generate relationships between changes in geophysical parameters and changes in reservoir parameters. Electrical conductivity changes are directly mapped to changes in water saturation; estimated changes in water saturation are used along with the observed changes in shear wave velocity to predict changes in reservoir pressure. The estimation of the spatial extent and amount of CO 2 relies on first removing the effects of the water saturation and pressure changes from the observed compressional velocity changes, producing a residual compressional velocity change. This velocity change is then interpreted in terms of increases in the CO 2 /oil ratio. Resulting images of the CO 2 /oil ratio show CO 2 -rich zones that are well correlated to the location of injection perforations, with the size of these zones also correlating to the amount of injected CO 2 . The images produced by this process are better correlated to the location and amount of injected CO 2 than are any of the individual

Validation of a spatial–temporal soil water movement and plant water uptake model

KAUST Repository

HEPPELL, J.

2014-06-01

© 2014, (publisher). All rights reserved. Management and irrigation of plants increasingly relies on accurate mathematical models for the movement of water within unsaturated soils. Current models often use values for water content and soil parameters that are averaged over the soil profile. However, many applications require models to more accurately represent the soil–plant–atmosphere continuum, in particular, water movement and saturation within specific parts of the soil profile. In this paper a mathematical model for water uptake by a plant root system from unsaturated soil is presented. The model provides an estimate of the water content level within the soil at different depths, and the uptake of water by the root system. The model was validated using field data, which include hourly water content values at five different soil depths under a grass/herb cover over 1 year, to obtain a fully calibrated system for plant water uptake with respect to climate conditions. When compared quantitatively to a simple water balance model, the proposed model achieves a better fit to the experimental data due to its ability to vary water content with depth. To accurately model the water content in the soil profile, the soil water retention curve and saturated hydraulic conductivity needed to vary with depth.

Measurement of electrical impedance of a Berea sandstone core during the displacement of saturated brine by oil and CO2 injections

Science.gov (United States)

Liu, Yu; Xue, Ziqiu; Park, Hyuck; Kiyama, Tamotsu; Zhang, Yi; Nishizawa, Osamu; Chae, Kwang-seok

2015-12-01

Complex electrical impedance measurements were performed on a brine-saturated Berea sandstone core while oil and CO2 were injected at different pressures and temperatures. The saturations of brine, oil, and CO2 in the core were simultaneously estimated using an X-ray computed tomography scanner. The formation factor of this Berea core and the resistivity indexes versus the brine saturations were calculated using Archie's law. The experimental results found different flow patterns of oil under different pressures and temperatures. Fingers were observed for the first experiment at 10 MPa and 40 °C. The fingers were restrained as the viscosity ratio of oil and water changed in the second (10 MPa and 25 °C) and third (5 MPa and 25 °C) experiments. The resistivity index showed an exponential increase with a decrease in brine saturation. The saturation exponent varied from 1.4 to 4.0 at different pressure and temperature conditions. During the oil injection procedure, the electrical impedance increased with oil saturation and was significantly affected by different oil distributions; therefore, the impedance varied whether the finger was remarkable or not, even if the oil saturation remained constant. During the CO2 injection steps, the impedance showed almost no change with CO2 saturation because the brine in the pores became immobile after the oil injection.

Factors Influencing the Formation of Corrosive Conditions in Puget Sound and the Extreme Conditions Observed During Summer 2015 Associated with the NE Pacific Warm Anomaly (a.k.a. The Blob)

Science.gov (United States)

Alin, S. R.; Curry, B.; Newton, J.; Feely, R. A.; Sutton, A.

2016-02-01

Puget Sound is a complex glacial estuarine system that receives input from many rivers and streams, in addition to runoff from the urban and agricultural environments surrounding the southern part of the Salish Sea ecosystem. A series of glacial sills restrict estuarine circulation such that intrusions of seawater only occur episodically, resulting in long residence times in some parts of the basin. Through survey cruises and stationary time-series, we have observed the dynamic biogeochemical cycles in various sub-basins of Puget Sound since 2008. Areas of Puget Sound with restricted circulation may experience conditions of high pCO2, low pH, and low aragonite saturation state throughout the year. Historically, the highest pCO2 and lowest pH and aragonite saturation states have been observed in early fall in Hood Canal. Upwelling of dense, nutrient- and CO2-rich but oxygen-poor water along the coast provides the marine source water for Puget Sound's deep waters. We estimate that marine waters entering Puget Sound via the Strait of Juan de Fuca are now corrosive 95% of the time, representing a 26% increase in frequency since the preindustrial era. Both river inputs and intense primary production in surface waters drive remineralization in deep waters of Puget Sound basins, contributing to the formation of corrosive conditions in waters below the productive surface. In addition, we estimate that regionally enhanced atmospheric CO2 content may result in an increase in CO2 uptake in the region. In 2015 many features of the seasonal carbon cycle were accelerated relative to earlier years, as a result of the influence of the NE Pacific warm anomaly. In southern Hood Canal, the surface spring bloom began weeks earlier than usual, and in July, we saw the lowest estimated pH and aragonite saturation values in deep waters observed to date in Washington marine environments, which was about two months earlier than historical seasonal minima in pH and aragonite saturation.

Decentralized control of discrete-time linear time invariant systems with input saturation

NARCIS (Netherlands)

Deliu, C.; Deliu, Ciprian; Malek, Babak; Roy, Sandip; Saberi, Ali; Stoorvogel, Antonie Arij

We study decentralized stabilization of discrete-time linear time invariant (LTI) systems subject to actuator saturation, using LTI controllers. The requirement of stabilization under both saturation constraints and decentralization impose obvious necessary conditions on the open-loop plant, namely

Decentralized control of discrete-time linear time invariant systems with input saturation

NARCIS (Netherlands)

Deliu, Ciprian; Deliu, C.; Malek, Babak; Roy, Sandip; Saberi, Ali; Stoorvogel, Antonie Arij

2009-01-01

We study decentralized stabilization of discrete time linear time invariant (LTI) systems subject to actuator saturation, using LTI controllers. The requirement of stabilization under both saturation constraints and decentralization impose obvious necessary conditions on the open-loop plant, namely

Gas hydrate saturation from acoustic impedance and resistivity logs in the shenhu area, south china sea

Science.gov (United States)

Wang, X.; Wu, S.; Lee, M.; Guo, Y.; Yang, S.; Liang, J.

2011-01-01

During the China's first gas hydrate drilling expedition -1 (GMGS-1), gas hydrate was discovered in layers ranging from 10 to 25 m above the base of gas hydrate stability zone in the Shenhu area, South China Sea. Water chemistry, electrical resistivity logs, and acoustic impedance were used to estimate gas hydrate saturations. Gas hydrate saturations estimated from the chloride concentrations range from 0 to 43% of the pore space. The higher gas hydrate saturations were present in the depth from 152 to 177 m at site SH7 and from 190 to 225 m at site SH2, respectively. Gas hydrate saturations estimated from the resistivity using Archie equation have similar trends to those from chloride concentrations. To examine the variability of gas hydrate saturations away from the wells, acoustic impedances calculated from the 3 D seismic data using constrained sparse inversion method were used. Well logs acquired at site SH7 were incorporated into the inversion by establishing a relation between the water-filled porosity, calculated using gas hydrate saturations estimated from the resistivity logs, and the acoustic impedance, calculated from density and velocity logs. Gas hydrate saturations estimated from acoustic impedance of seismic data are ???10-23% of the pore space and are comparable to those estimated from the well logs. The uncertainties in estimated gas hydrate saturations from seismic acoustic impedances were mainly from uncertainties associated with inverted acoustic impedance, the empirical relation between the water-filled porosities and acoustic impedances, and assumed background resistivity. ?? 2011 Elsevier Ltd.

Gas production potential of disperse low-saturation hydrate accumulations in oceanic sediments

International Nuclear Information System (INIS)

Moridis, George J.; Sloan, E. Dendy

2007-01-01

In this paper, we evaluate the gas production potential of disperse, low-saturation (S H H hydrate-bearing sediments subject to depressurization-induced dissociation over a 10-year production period. We investigate the sensitivity of items (a)-(c) to the following hydraulic properties, reservoir conditions, and operational parameters: intrinsic permeability, porosity, pressure, temperature, hydrate saturation, and constant pressure at which the production well is kept. The results of this study indicate that, despite wide variations in the aforementioned parameters (covering the entire spectrum of such deposits), gas production is very limited, never exceeding a few thousand cubic meters of gas during the 10-year production period. Such low production volumes are orders of magnitude below commonly accepted standards of economic viability, and are further burdened with very unfavorable gas-to-water ratios. The unequivocal conclusion from this study is that disperse, low-S H hydrate accumulations in oceanic sediments are not promising targets for gas production by means of depressurization-induced dissociation, and resources for early hydrate exploitation should be focused elsewhere

Saturated and unsaturated stability analysis of slope subjected to rainfall infiltration

OpenAIRE

Gofar Nurly; Rahardjo Harianto

2017-01-01

This paper presents results of saturated and unsaturated stability analysis of typical residual slopes subjected to rainfall infiltration corresponds to 50 years rainfall return period. The slope angles considered were 45° and 70°. The saturated stability analyses were carried out for original and critical ground water level commonly considered by practicing engineer. The analyses were conducted using limit equilibrium method. Unsaturated stability analyses used combination of coupled stress–...

Barley seed radiosensitivity following post-hydration in oxygen-, nitrogen- and nitrous oxide-saturated water, 1; Influence of caffeine and t-butyl alcohol

Energy Technology Data Exchange (ETDEWEB)

Singh, S.P.; Kesavan, P.C. (Jawaharlal Nehru Univ., New Delhi (India). School of Life Sciences)

1990-06-01

Dry ({approx}3.5 and 4.0 per cent moisture content) barley seeds were exposed to 350 Gy of {sup 60}Co-{gamma}-rays in vacuo and post-hydrated at 4degC for 8 h in O{sub 2}-, N{sub 2}-, or N{sub 2}O-saturated water. The effect of caffeine and t-butyl alcohol (t-BuOH) dissolved in the post-hydration medium on the magnitude of damage developing under these three different gaseous circumstances was studied. The post-irradiation damage and its modification by caffeine and t-BuOH was assessed in terms of 8-day-old seedling injury, peroxidase activity and total peroxides in the 8-day-old seedlings. Post-irradiation O{sub 2}-saturated hydration caused maximal 8-day-old seedling injury, and increased peroxidase activity with concomitant reduction in total peroxides. Both caffeine and t-BuOH afforded significant radioprotection against post-irradiation O{sub 2}-dependent damage. Post-irradiation N{sub 2}O-saturated hydration was even more significantly radioprotective than the N{sub 2}-saturated post-hydration. Under these circumstances, t-BuOH exerted no effect whatsoever on the N{sub 2}- and N{sub 2}O-mediated post-irradiation damage. Caffeine, on the other hand, significantly potentiated these two components of damage. A brief consideration of the physicochemical events which possibly account for the observed effects is presented. (author).

Potential benefits of saturation cycle with two-phase refrigerant injection

International Nuclear Information System (INIS)

Lee, Hoseong; Hwang, Yunho; Radermacher, Reinhard; Chun, Ho-Hwan

2013-01-01

In this paper, a saturation cycle is proposed to enhance a vapor compression cycle performance by reducing thermodynamic losses associated with single phase gas compression and isenthalpic expansion. In order to approach the saturation cycle, a two-phase refrigerant injection technique is applied to the multi-stage cycle. This multi-stage cycle with different options is modeled, and its performance is evaluated under ASHRAE standard operating conditions for air conditioning systems. Moreover, the two-phase refrigerant injection cycle is compared with the typical vapor injection cycle which is utilizing the internal heat exchanger or the flash tank. Low GWP refrigerants are applied to this two-phase refrigerant injection cycle. In terms of the COP and its improvement, R123 has a higher potential than any other refrigerants in the multi-stage cycle. Lastly, practical ideas realizing the saturation cycle are discussed such as multi-stage phase separator, phase separator with helical structure inside, and injection location of the compressor. -- Highlights: • A saturation cycle is proposed to enhance the vapor compression cycle performance. • Two-phase refrigerant injection technique is applied to the multi-stage cycle. • Modeling results of the proposed cycle show the significant performance improvement. • Low GWP refrigerants are applied and R123 shows the highest performance. • New parameters, α and ε, are used to show the potential of the saturation cycle

Response of the Water Level in a Well to Earth Tides and Atmospheric Loading Under Unconfined Conditions

Science.gov (United States)

Rojstaczer, Stuart; Riley, Francis S.

1990-08-01

The response of the water level in a well to Earth tides and atmospheric loading under unconfined conditions can be explained if the water level is controlled by the aquifer response averaged over the saturated depth of the well. Because vertical averaging tends to diminish the influence of the water table, the response is qualitatively similar to the response of a well under partially confined conditions. When the influence of well bore storage can be ignored, the response to Earth tides is strongly governed by a dimensionless aquifer frequency Q'u. The response to atmospheric loading is strongly governed by two dimensionless vertical fluid flow parameters: a dimensionless unsaturated zone frequency, R, and a dimensionless aquifer frequency Qu. The differences between Q'u and Qu are generally small for aquifers which are highly sensitive to Earth tides. When Q'u and Qu are large, the response of the well to Earth tides and atmospheric loading approaches the static response of the aquifer under confined conditions. At small values of Q'u and Qu, well response to Earth tides and atmospheric loading is strongly influenced by water table drainage. When R is large relative to Qu, the response to atmospheric loading is strongly influenced by attenuation and phase shift of the pneumatic pressure signal in the unsaturated zone. The presence of partial penetration retards phase advance in well response to Earth tides and atmospheric loading. When the theoretical response of a phreatic well to Earth tides and atmospheric loading is fit to the well response inferred from cross-spectral estimation, it is possible to obtain estimates of the pneumatic diffusivity of the unsaturated zone and the vertical hydraulic conductivity of the aquifer.

Stable isotopes of authigenic minerals in variably-saturated fractured tuff

International Nuclear Information System (INIS)

Weber, D.S.; Evans, D.D.

1988-11-01

Identifying stable isotope variation and mineralogical changes in fractured rock may help establish the history of climatic and geomorphological processes that might affect the isolation properties of a waste repository site. This study examines the use of the stable isotope ratios of oxygen ( 18 O/ 16 O) and carbon ( 13 C/ 12 C) in authigenic minerals as hydrogeochemical tools tracing low-temperature rock-water interaction in variably-saturated fractured stuff. Isotopic compositions of fracture-filling and rock matrix minerals in the Apache Leap tuff, near Superior, Arizona were concordant with geothermal temperatures and in equilibrium with water isotopically similar to present-day meteoric water and groundwater. Oxygen and carbon isotope ratios of fracture-filling, in unsaturated fractured tuff, displayed an isotopic gradient believed to result from near-surface isotopic enrichment due to evaporation rather than the effects of rock-water interaction. Oxygen isotope ratios of rock matrix opal samples exhibited an isotopic gradient believed to result from, leaching and reprecipitation of silica at depth. Methods and results can be used to further define primary flowpaths and the movement of water in variably-saturated fractured rock. 71 refs., 23 figs., 3 tabs

Stable isotopes of authigenic minerals in variably-saturated fractured tuff

Energy Technology Data Exchange (ETDEWEB)

Weber, D.S.; Evans, D.D.

1988-11-01

Identifying stable isotope variation and mineralogical changes in fractured rock may help establish the history of climatic and geomorphological processes that might affect the isolation properties of a waste repository site. This study examines the use of the stable isotope ratios of oxygen ({sup 18}O/{sup 16}O) and carbon ({sup 13}C/{sup 12}C) in authigenic minerals as hydrogeochemical tools tracing low-temperature rock-water interaction in variably-saturated fractured stuff. Isotopic compositions of fracture-filling and rock matrix minerals in the Apache Leap tuff, near Superior, Arizona were concordant with geothermal temperatures and in equilibrium with water isotopically similar to present-day meteoric water and groundwater. Oxygen and carbon isotope ratios of fracture-filling, in unsaturated fractured tuff, displayed an isotopic gradient believed to result from near-surface isotopic enrichment due to evaporation rather than the effects of rock-water interaction. Oxygen isotope ratios of rock matrix opal samples exhibited an isotopic gradient believed to result from, leaching and reprecipitation of silica at depth. Methods and results can be used to further define primary flowpaths and the movement of water in variably-saturated fractured rock. 71 refs., 23 figs., 3 tabs.

State-Feedback Control for Fractional-Order Nonlinear Systems Subject to Input Saturation

Directory of Open Access Journals (Sweden)

Junhai Luo

2014-01-01

Full Text Available We give a state-feedback control method for fractional-order nonlinear systems subject to input saturation. First, a sufficient condition is derived for the asymptotical stability of a class of fractional-order nonlinear systems. Then based on Gronwall-Bellman lemma and a sector bounded condition of the saturation function, a linear state-feed back controller is designed. Finally, two simulation examples are presented to show the validity of the proposed method.

Seasonal trends of light-saturated net photosynthesis and stomatal conductance of loblolly pine trees grown in contrasting environments of nutrition, water and carbon dioxide

Science.gov (United States)

Ramesh Murthy; Stanley J. Zarnoch; P.M. Dougherty

1997-01-01

Repeated measures analysis was used to evaluate the effect of long-term CO2 enhancement on seasonal trends of light-saturated rates of net photosynthesis (Asat) and stomatal conductance to water vapour (gsat) of 9-year-old loblolly pine (Pinus taeda L.; trees grown in a 2x2...

Passive flux meter measurement of water and nutrient flux in saturated porous media: bench-scale laboratory tests.

Science.gov (United States)

Cho, Jaehyun; Annable, Michael D; Jawitz, James W; Hatfield, Kirk

2007-01-01

The passive nutrient flux meter (PNFM) is introduced for simultaneous measurement of both water and nutrient flux through saturated porous media. The PNFM comprises a porous sorbent pre-equilibrated with a suite of alcohol tracers, which have different partitioning coefficients. Water flux was estimated based on the loss of loaded resident tracers during deployment, while nutrient flux was quantified based on the nutrient solute mass captured on the sorbent. An anionic resin, Lewatit 6328 A, was used as a permeable sorbent and phosphate (PO4(3-)) was the nutrient studied. The phosphate sorption capacity of the resin was measured in batch equilibration tests as 56 mg PO4(3-) g(-1), which was determined to be adequate capacity to retain PO4(3-) loads intercepted over typical PNFM deployment periods in most natural systems. The PNFM design was validated with bench-scale laboratory tests for a range of 9.8 to 28.3 cm d(-1) Darcy velocities and 6 to 43 h deployment durations. Nutrient and water fluxes measured by the PNFM averaged within 6 and 12% of the applied values, respectively, indicating that the PNFM shows promise as a tool for simultaneous measurement of water and nutrient fluxes.

Decomposition of atmospheric water content into cluster contributions based on theoretical association equilibrium constants

International Nuclear Information System (INIS)

Slanina, Z.

1987-01-01

Water vapor is treated as an equilibrium mixture of water clusters (H 2 O)/sub i/ using quantum-chemical evaluation of the equilibrium constants of water associations. The model is adapted to the conditions of atmospheric humidity, and a decomposition algorithm is suggested using the temperature and mass concentration of water as input information and used for a demonstration of evaluation of the water oligomer populations in the Earth's atmosphere. An upper limit of the populations is set up based on the water content in saturated aqueous vapor. It is proved that the cluster population in the saturated water vapor, as well as in the Earth's atmosphere for a typical temperature/humidity profile, increases with increasing temperatures

Use of experimentally determined Henry's Law and salting-out constants for ethanol in seawater for determination of the saturation state of ethanol in coastal waters.

Science.gov (United States)

Willey, Joan D; Powell, Jacqueline P; Avery, G Brooks; Kieber, Robert J; Mead, Ralph N

2017-09-01

The Henry's law constant for ethanol in seawater was experimentally determined to be 221 ± 4 M/atm at 22 °C compared with 247 ± 6 M/atm in pure water. The salting out coefficient for ethanol was 0.13 M -1 . In seawater ln(K H ) = -(12.8 ± 0.7) + (5310 ± 197)/T where K H is in M atm -1 and temperature is in K. This plus the salting out coefficient allow calculation of K H for any estuarine or sea water between 1 and 35 °C. High concentrations of dissolved organic carbon do not affect K H values in fresh or seawater. Nearshore surface waters were usually undersaturated with respect to gas phase ethanol except when air concentrations decreased, whereas surface seawater 40 km from shore was supersaturated. The percent saturation in surface waters is driven primarily by changes in air concentrations because these change quickly (hours) and more extensively than surface water. This study allows calculation of ethanol saturation states from air and surface water concentrations which is a necessary step to define the role of surface oceans in the global biogeochemical cycling of ethanol both now and in the future as use of ethanol biofuel continues to grow. Copyright © 2017 Elsevier Ltd. All rights reserved.

Microscopic analysis of saturable absorbers: Semiconductor saturable absorber mirrors versus graphene

Energy Technology Data Exchange (ETDEWEB)

Hader, J.; Moloney, J. V. [Nonlinear Control Strategies, Inc., 3542 N. Geronimo Ave., Tucson, Arizona 85705 (United States); College of Optical Sciences, University of Arizona, Tucson, Arizona 85721 (United States); Yang, H.-J.; Scheller, M. [College of Optical Sciences, University of Arizona, Tucson, Arizona 85721 (United States); Koch, S. W. [Department of Physics and Materials Sciences Center, Philipps Universität Marburg, Renthof 5, 35032 Marburg (Germany)

2016-02-07

Fully microscopic many-body calculations are used to study the influence of strong sub-picosecond pulses on the carrier distributions and corresponding optical response in saturable absorbers used for mode-locking—semiconductor (quantum well) saturable absorber mirrors (SESAMs) and single layer graphene based saturable absorber mirrors (GSAMs). Unlike in GSAMs, the saturation fluence and recovery time in SESAMs show a strong spectral dependence. While the saturation fluence in the SESAM is minimal at the excitonic bandgap, the optimal recovery time and least pulse distortion due to group delay dispersion are found for excitation higher in the first subband. For excitation near the SESAM bandgap, the saturation fluence is about one tenth of that in the GSAM. At energies above the bandgap, the fluences in both systems become similar. A strong dependence of the saturation fluence on the pulse width in both systems is caused by carrier relaxation during the pulse. The recovery time in graphene is found to be about two to four times faster than that in the SESAMs. The occurrence of negative differential transmission in graphene is shown to be caused by dopant related carriers. In SESAMs, a negative differential transmission is found when exciting below the excitonic resonance where excitation induced dephasing leads to an enhancement of the absorption. Comparisons of the simulation data to the experiment show a very good quantitative agreement.

Effectiveness of immediate bonding of etch-and-rinse adhesives to simplified ethanol-saturated dentin

Directory of Open Access Journals (Sweden)

Leandro Afonso Guimarães

2012-04-01

Full Text Available This study examined the immediate bond strength of etch-and-rinse adhesives to demineralized dentin saturated with either water or absolute ethanol. The research hypothesis was that there would be no difference in bond strength to dentin between water or ethanol wet-bonding techniques. The medium dentin of 20 third molars was exposed (n = 5. The dentin surface was then acid-etched, left moist and randomly assigned to be saturated via either water wet-bonding (WBT or absolute ethanol wet-bonding (EBT. The specimens were then treated with one of the following etch-and-rinse adhesive systems: a 3-step, water-based system (Adper Scotchbond Multipurpose, or SBMP or a 2-step, ethanol/water-based system (Adper Single Bond 2, or SB. Resin composite build-ups were then incrementally constructed. After water storage for 24 h at 37°C, the tensile strength of the specimens was tested in a universal testing machine (0.5 mm/min. Data were analyzed by two-way ANOVA and Tukey's test (a = 5%. The failure modes were verified using a stereomicroscope (40'. For both adhesives, no significant difference in bond strength was observed between WBT and EBT (p > 0.05. The highest bond strength was observed for SB, regardless of the bonding technique (p < 0.05. No significant interaction between adhesives and bonding techniques was noticed (p = 0.597. There was a predominance of adhesive failures for all tested groups. The EBT and WBT displayed similar immediate bond strength means for both adhesives. The SB adhesive exhibited higher means for all conditions tested. Further investigations are needed to evaluate long-term bonding to dentin mediated by commercial etch-and-rinse adhesives using the EBT approach.

The vapour pressures over saturated aqueous solutions of sodium and potassium acetates, chlorates, and perchlorates

Energy Technology Data Exchange (ETDEWEB)

Apelblat, Alexander [Department of Chemical Engineering, Ben Gurion University of the Negev, Beer Sheva 84105 (Israel)]. E-mail: apelblat@bgu.ac.il; Manzurola, Emanuel [Department of Chemical Engineering, Ben Gurion University of the Negev, Beer Sheva 84105 (Israel)

2007-08-15

Vapour pressures of water over saturated solutions of sodium acetate, potassium acetate, sodium perchlorate, and potassium perchlorate were determined over the (278 to 318) K temperature range and compared with available in the literature data. The cases of saturated solutions of sodium chlorate and potassium chlorate are also considered. The determined vapour pressures were used to obtain the water activities, the osmotic coefficients, and the molar enthalpies of vaporization in considered systems.

Water Flow in Karst Aquifer Considering Dynamically Variable Saturation Conduit

Science.gov (United States)

Tan, Chaoqun; Hu, Bill X.

2017-04-01

The karst system is generally conceptualized as dual-porosity system, which is characterized by low conductivity and high storage continuum matrix and high conductivity and quick flow conduit networks. And so far, a common numerical model for simulating flow in karst aquifer is MODFLOW2005-CFP, which is released by USGS in 2008. However, the steady-state approach for conduit flow in CFP is physically impractical when simulating very dynamic hydraulics with variable saturation conduit. So, we adopt the method proposed by Reimann et al. (2011) to improve current model, in which Saint-Venant equations are used to model the flow in conduit. Considering the actual background that the conduit is very big and varies along flow path and the Dirichlet boundary varies with rainfall in our study area in Southwest China, we further investigate the influence of conduit diameter and outflow boundary on numerical model. And we also analyze the hydraulic process in multi-precipitation events. We find that the numerical model here corresponds well with CFP for saturated conduit, and it could depict the interaction between matrix and conduit during very dynamic hydraulics pretty well compare with CFP.

Effects of sucrose concentration and water deprivation on Pavlovian conditioning and responding for conditioned reinforcement.

Science.gov (United States)

Tabbara, Rayane I; Maddux, Jean-Marie N; Beharry, Priscilla F; Iannuzzi, Jessica; Chaudhri, Nadia

2016-04-01

An appetitive Pavlovian conditioned stimulus (CS) can predict an unconditioned stimulus (US) and acquire incentive salience. We tested the hypothesis that US intensity and motivational state of the subject would influence Pavlovian learning and impact the attribution of incentive salience to an appetitive Pavlovian CS. To this end, we examined the effects of sucrose concentration and water deprivation on the acquisition of Pavlovian conditioning and responding for a conditioned reinforcer. Male Long-Evans rats (Harlan; 220-240 g) receiving 3% (3S) or 20% (20S) sucrose were either non-water deprived or given water for 1 hr per day. During Pavlovian conditioning sessions, half the rats in each concentration and deprivation condition received a 10-s CS paired with 0.2 ml of sucrose (16 trials/session; 3.2 ml/session). The remainder received unpaired CS and US presentations. Entries into a port where sucrose was delivered were recorded. Next, responding for conditioned reinforcement was tested, wherein pressing an active lever produced the CS and pressing an inactive lever had no consequences. CS-elicited port entries increased, and latency to the first CS-elicited port entry decreased across sessions in paired groups. Water deprivation augmented these effects, whereas sucrose concentration had no significant impact on behavior. Responding for conditioned reinforcement was observed in the 20S water-deprived, paired group. Thus, water deprivation can facilitate the acquisition of Pavlovian conditioning, potentially by enhancing motivational state, and a high-intensity US and a high motivational state can interact to heighten the attribution of incentive salience to an appetitive Pavlovian CS. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Nighttime oxidation of surfactants at the air–water interface: effects of chain length, head group and saturation

Directory of Open Access Journals (Sweden)

F. Sebastiani

2018-03-01

Full Text Available Reactions of the key atmospheric nighttime oxidant NO3 with organic monolayers at the air–water interface are used as proxies for the ageing of organic-coated aqueous aerosols. The surfactant molecules chosen for this study are oleic acid (OA, palmitoleic acid (POA, methyl oleate (MO and stearic acid (SA to investigate the effects of chain length, head group and degree of unsaturation on the reaction kinetics and products formed. Fully and partially deuterated surfactants were studied using neutron reflectometry (NR to determine the reaction kinetics of organic monolayers with NO3 at the air–water interface for the first time. Kinetic modelling allowed us to determine the rate coefficients for the oxidation of OA, POA and MO monolayers to be (2.8±0.7 × 10−8, (2.4±0.5 × 10−8and (3.3±0.6 × 10−8 cm2 molecule−1 s−1 for fitted initial desorption lifetimes of NO3 at the closely packed organic monolayers, τd, NO3, 1, of 8.1±4.0, 16±4.0 and 8.1±3.0 ns, respectively. The approximately doubled desorption lifetime found in the best fit for POA compared to OA and MO is consistent with a more accessible double bond associated with the shorter alkyl chain of POA facilitating initial NO3 attack at the double bond in a closely packed monolayer. The corresponding uptake coefficients for OA, POA and MO were found to be (2.1±0.5 × 10−3, (1.7±0.3 × 10−3 and (2.1±0.4 × 10−3, respectively. For the much slower NO3-initiated oxidation of the saturated surfactant SA we estimated a loss rate of approximately (5±1 × 10−12 cm2 molecule−1 s−1, which we consider to be an upper limit for the reactive loss, and estimated an uptake coefficient of ca. (5±1 × 10−7. Our investigations demonstrate that NO3 will contribute substantially to the processing of unsaturated surfactants at the air–water interface during nighttime given its reactivity is ca. 2 orders of magnitude higher

Mobility and survival of sulphate-reducing bacteria in compacted and fully water saturated bentonite - microstructural aspects

Energy Technology Data Exchange (ETDEWEB)

Pusch, R. [Geodevelopment AB, Lund (Sweden)

1999-12-01

Sulphate-reducing bacteria will not be able to enter MX-80 buffer clay with the intended bulk density, i.e. 1900-2100 kg/m{sup 3}. Nor will they be able to survive and migrate in such environment. The only circumstances under which sulphate-reducing bacteria can enter, survive and migrate in engineered soil barriers in a KBS-3-type repository are those prevailing in backfills with lower MX-80 contents than about 10 % or in more smectite-rich, poorly compacted backfills saturated with electrolyte-rich pore water with Ca as dominating cation. In the phase of hydration and expansion of canister-embedding buffer, bacteria can enter the initially very soft clay gel at the rock/buffer contact to a depth of about a centimeter.

Mobility and survival of sulphate-reducing bacteria in compacted and fully water saturated bentonite - microstructural aspects

International Nuclear Information System (INIS)

Pusch, R.

1999-12-01

Sulphate-reducing bacteria will not be able to enter MX-80 buffer clay with the intended bulk density, i.e. 1900-2100 kg/m 3 . Nor will they be able to survive and migrate in such environment. The only circumstances under which sulphate-reducing bacteria can enter, survive and migrate in engineered soil barriers in a KBS-3-type repository are those prevailing in backfills with lower MX-80 contents than about 10 % or in more smectite-rich, poorly compacted backfills saturated with electrolyte-rich pore water with Ca as dominating cation. In the phase of hydration and expansion of canister-embedding buffer, bacteria can enter the initially very soft clay gel at the rock/buffer contact to a depth of about a centimeter

Phytosterol-based edible oleogels: A novel way of replacing saturated fat in food.

Science.gov (United States)

Matheson, A; Dalkas, G; Clegg, P S; Euston, S R

2018-06-01

This article presents a summary of recent results relating to phytosterol oleogels. Oleogels represent a novel way of replacing saturated fat in food, whilst phytosterols have been shown to actively lower low-density lipoprotein (LDL)- cholesterol levels. There are a number of technical challenges to exploiting phytosterol oleogels, including a high sensitivity to water. To facilitate their incorporation into food, the fundamental physiochemical processes which mediate the formation of these gels and two different approaches to produce phytosterol oleogels that are stable in the presence of water were explored as part of the recent Biotechnology and Biological Sciences Research Council (BBSRC)-Diet and Health Research Industry Club (DRINC)-funded Edible Oleogels for Reduction of Saturated Fat project. This report summarises the findings, which will support the development of healthier food products that are lower in saturated fat and acceptable to consumers.

Transient response of a cylindrical cavity in viscoelastic saturated porous medium

Directory of Open Access Journals (Sweden)

LIU Tao

2016-10-01

Full Text Available The study on dynamic characteristics for fluid-solid coupling system in saturated porous medium is of significant academic value and potential application foreground.In this paper,the transient response of a cylindrical cavity in infinite viscoelastic saturated porous medium with the circular lining is studied,and the corresponding results can be used in the design of foundation engineering,such as the tunnel analyses in saturated soil,the nuclear waste disposal engineering,and the exploitation and utilization of geothermal reservoirs and so on.Firstly,based on the porous media theory,the governing equations of coupled system are presented,and the corresponding boundary conditions,initial conditions as well as the joint conditions are derived.Then,the differential quadrature element method and the second-order backward difference scheme are applied to discretize the governing differential equations of the coupled system on the spatial and temporal domains,respectively.Finally,the Newton-Raphson method is adopted to solve the discretization equations with the initial conditions,the transient responses of the coupled system are analyzed,the effects of the parameters are considered,and the validity of the numerical method is verified.

Effect of Water on Coal Strength | Singh | Momona Ethiopian Journal ...

African Journals Online (AJOL)

Water content is one of the most important factors influencing the rock strength. The present study has been conducted to see how coal strength changes under dry and water saturated conditions. The study reveals that the strength of coal decreases with increasing moisture. For rock mechanics and rock engineering ...

Investigation and mitigation of condensation induced water hammer by stratified flow experiments

Science.gov (United States)

Kadakia, Hiral J.

This research primarily focuses on the possibility of using stratified flow in preventing an occurrence of condensation induced water hammer (CIWH) in horizontal pipe involving steam and subcooled water. A two-phase flow loop simulating the passive safety systems of an advanced light water reactor was constructed and a series of stratified flow experiments were carried out involving a system of subcooled water, saturated water, and steam. Special instruments were designed to measure steam flow rate and subcooled liquid velocity. These experiments showed that when flow field conditions meet certain criteria CIWH does occur. Flow conditions used in experiments were typically observed in passive safety systems of an advanced light water cooled reactor. This research summarizes a) literature research and other experimental data that signify an occurrence of CIWH, b) experiments in an effort to show an occurrence of CIWH and the ability to prevent CIWH, c) qualitative and quantitative results to underline the mechanism of CIWH, d) experiments that show CIWH can be prevented under certain conditions, and e) guidelines for the safe operating conditions. Based on initial experiment results it was observed that Bernoulli's effect can play an important role in wave formation and instability. A separate effect table top experiment was constructed with plexi-glass. A series of entrance effect tests and stratified experiments were carried out with different fluids to study wave formation and wave bridging. Special test series experiments were carried out to investigate the presence of a saturated layer. The effect of subcooled water and steam flow on wedge length and depth were recorded. These experiments helped create a model which calculates wedge and depth of wedge for a given condition of steam and subcooled water. A very good comparison between the experiment results and the model was obtained. These experiments also showed that the presence of saturated layer can mitigate

Effect of soil saturation on denitrification in a grassland soil

Directory of Open Access Journals (Sweden)

L. M. Cardenas

2017-10-01

Full Text Available Nitrous oxide (N2O is of major importance as a greenhouse gas and precursor of ozone (O3 destruction in the stratosphere mostly produced in soils. The soil-emitted N2O is generally predominantly derived from denitrification and, to a smaller extent, nitrification, both processes controlled by environmental factors and their interactions, and are influenced by agricultural management. Soil water content expressed as water-filled pore space (WFPS is a major controlling factor of emissions and its interaction with compaction, has not been studied at the micropore scale. A laboratory incubation was carried out at different saturation levels for a grassland soil and emissions of N2O and N2 were measured as well as the isotopocules of N2O. We found that flux variability was larger in the less saturated soils probably due to nutrient distribution heterogeneity created from soil cracks and consequently nutrient hot spots. The results agreed with denitrification as the main source of fluxes at the highest saturations, but nitrification could have occurred at the lower saturation, even though moisture was still high (71 % WFSP. The isotopocules data indicated isotopic similarities in the wettest treatments vs. the two drier ones. The results agreed with previous findings where it is clear there are two N pools with different dynamics: added N producing intense denitrification vs. soil N resulting in less isotopic fractionation.

A general approach for defining the macroscopic free energy density of saturated porous media at finite strains under non-isothermal conditions

International Nuclear Information System (INIS)

Gajo, A.

2011-01-01

A general approach is proposed for defining the macroscopic free energy density function (and its complement, the free enthalpy) of a saturated porous medium submitted to finite deformations under non-isothermal conditions, in the case of compressible fluid and solid constituents. Reference is made to an elementary volume treated as an 'open system', moving with the solid skeleton. The proposed free energy depends on the generalised strains (namely an appropriate measure of the strain of the solid skeleton and the variation in fluid mass content) and the absolute temperatures of the solid and fluid phases (which are assumed to differ from each other for the sake of generality). This macroscopic energy proves to be a potential for the generalised stresses (namely the associated measure of the total stress and the free enthalpy of the pore fluid per unit mass) and the entropies of the solid and fluid phases. In contrast with mixture theories, the resulting free energy is not the simple sum of the free energies of the single constituents. Two simplified cases are examined in detail, i.e. the semi-linear theory (originally proposed for isothermal conditions and extended here to non-isothermal problems) and the linear theory. The proposed approach paves the way to the consistent non-isothermal-hyper-elastic-plastic modelling of saturated porous media with a compressible fluid and solid constituents. (authors)

Impact of sample saturation on the detected porosity of hardened concrete using low temperature calorimetry

DEFF Research Database (Denmark)

Wu, Min; Johannesson, Björn

2014-01-01

The present work studied the impact of sample saturation on the analysis of pore volume and pore size distribution by low temperature (micro-)calorimetry. The theoretical background was examined, which emphasizes that the freezing/melting temperature of water/ice confined in non-fully saturated p...

Surface-Water Conditions in Georgia, Water Year 2005

Science.gov (United States)

Painter, Jaime A.; Landers, Mark N.

2007-01-01

INTRODUCTION The U.S. Geological Survey (USGS) Georgia Water Science Center-in cooperation with Federal, State, and local agencies-collected surface-water streamflow, water-quality, and ecological data during the 2005 Water Year (October 1, 2004-September 30, 2005). These data were compiled into layers of an interactive ArcReaderTM published map document (pmf). ArcReaderTM is a product of Environmental Systems Research Institute, Inc (ESRI?). Datasets represented on the interactive map are * continuous daily mean streamflow * continuous daily mean water levels * continuous daily total precipitation * continuous daily water quality (water temperature, specific conductance dissolved oxygen, pH, and turbidity) * noncontinuous peak streamflow * miscellaneous streamflow measurements * lake or reservoir elevation * periodic surface-water quality * periodic ecological data * historical continuous daily mean streamflow discontinued prior to the 2005 water year The map interface provides the ability to identify a station in spatial reference to the political boundaries of the State of Georgia and other features-such as major streams, major roads, and other collection stations. Each station is hyperlinked to a station summary showing seasonal and annual stream characteristics for the current year and for the period of record. For continuous discharge stations, the station summary includes a one page graphical summary page containing five graphs, a station map, and a photograph of the station. The graphs provide a quick overview of the current and period-of-record hydrologic conditions of the station by providing a daily mean discharge graph for the water year, monthly statistics graph for the water year and period of record, an annual mean streamflow graph for the period of record, an annual minimum 7-day average streamflow graph for the period of record, and an annual peak streamflow graph for the period of record. Additionally, data can be accessed through the layer's link

A framework for sourcing of evaporation between saturated and unsaturated zone in bare soil condition

OpenAIRE

Balugani, E.; Lubczynski, M.W.; Metselaar, Klaas

2016-01-01

Sourcing subsurface evaporation (Ess) into groundwater (Eg) and unsaturated zone (Eu) components has received little scientific attention so far, despite its importance in water management and agriculture. We propose a novel sourcing framework, with its implementation in dedicated post-processing software called SOURCE (used along with the HYDRUS1D model), to study evaporation sourcing dynamics, define quantitatively “shallow” and “deep” water table conditions and test the applicability of wa...

Prediction of the critical heat flux for saturated upward flow boiling water in vertical narrow rectangular channels

International Nuclear Information System (INIS)

Choi, Gil Sik; Chang, Soon Heung; Jeong, Yong Hoon

2016-01-01

A study, on the theoretical method to predict the critical heat flux (CHF) of saturated upward flow boiling water in vertical narrow rectangular channels, has been conducted. For the assessment of this CHF prediction method, 608 experimental data were selected from the previous researches, in which the heated sections were uniformly heated from both wide surfaces under the high pressure condition over 41 bar. For this purpose, representative previous liquid film dryout (LFD) models for circular channels were reviewed by using 6058 points from the KAIST CHF data bank. This shows that it is reasonable to define the initial condition of quality and entrainment fraction at onset of annular flow (OAF) as the transition to annular flow regime and the equilibrium value, respectively, and the prediction error of the LFD model is dependent on the accuracy of the constitutive equations of droplet deposition and entrainment. In the modified Levy model, the CHF data are predicted with standard deviation (SD) of 14.0% and root mean square error (RMSE) of 14.1%. Meanwhile, in the present LFD model, which is based on the constitutive equations developed by Okawa et al., the entire data are calculated with SD of 17.1% and RMSE of 17.3%. Because of its qualitative prediction trend and universal calculation convergence, the present model was finally selected as the best LFD model to predict the CHF for narrow rectangular channels. For the assessment of the present LFD model for narrow rectangular channels, effective 284 data were selected. By using the present LFD model, these data are predicted with RMSE of 22.9% with the dryout criterion of zero-liquid film flow, but RMSE of 18.7% with rivulet formation model. This shows that the prediction error of the present LFD model for narrow rectangular channels is similar with that for circular channels.

Delineating saturated conduit patterns and dimensions in the upper Floridan aquifer through numerical groundwater flow modeling (Invited)

Science.gov (United States)

Kincaid, T. R.; Meyer, B. A.

2009-12-01

In groundwater flow modeling, aquifer permeability is typically defined through model calibration. Since the pattern and size of conduits are part of a karstic permeability framework, those parameters should be constrainable through the same process given a sufficient density of measured conditions. H2H Associates has completed a dual-permeability steady-state model of groundwater flow through the western Santa Fe River Basin, Florida from which a 380.9 km network of saturated conduits was delineated through model calibration to heads and spring discharges. Two calibration datasets were compiled describing average high-water and average low-water conditions based on heads at 145 wells and discharge from 18 springs for the high-water scenario and heads at 188 wells and discharge from 9 springs for the low-water scenario. An initial conduit network was defined by assigning paths along mapped conduits and inferring paths along potentiometric troughs between springs and swallets that had been connected by groundwater tracing. These initial conduit assignments accounted for only 13.75 and 34.1 km of the final conduit network respectively. The model was setup using FEFLOW™ where conduits were described as discrete features embedded in a porous matrix. Flow in the conduits was described by the Manning-Strickler equation where variables for conduit area and roughness were used to adjust the volume and velocity of spring flows. Matrix flow was described by Darcy’s law where hydraulic conductivity variations were limited to three geologically defined internally homogeneous zones that ranged from ~2E-6 m/s to ~4E-3 m/s. Recharge for both the high-water and low-water periods was determined through a water budget analysis where variations were restricted to nine zones defined by land-use. All remaining variations in observed head were then assumed to be due to conduits. The model was iteratively calibrated to the high-water and low-water datasets wherein the location, size

Rectifier transformer saturation on commutation failure

International Nuclear Information System (INIS)

Lu, E.; Bronner, G.

1989-01-01

The rectifier transformer's service differs from the power transformer's service because of the rectifier load. Under certain fault conditions, such as a commutation failure, d.c. magnetization may be introduced into the rectifier transformer cores, resulting in possible saturation of the magnetic circuit, thus in degradation of the performance of the transformer. It is the purpose of this paper to present an approach for evaluating the electromagnetic transient process under such a fault condition. The studies were made on the operating 1000MVA converter system at the Princeton Plasma Physics Laboratory

Optimal oxygen saturation in premature infants

Directory of Open Access Journals (Sweden)

Meayoung Chang

2011-09-01

Full Text Available There is a delicate balance between too little and too much supplemental oxygen exposure in premature infants. Since underuse and overuse of supplemental oxygen can harm premature infants, oxygen saturation levels must be monitored and kept at less than 95% to prevent reactive oxygen species-related diseases, such as retinopathy of prematurity and bronchopulmonary dysplasia. At the same time, desaturation below 80 to 85% must be avoided to prevent adverse consequences, such as cerebral palsy. It is still unclear what range of oxygen saturation is appropriate for premature infants; however, until the results of further studies are available, a reasonable target for pulse oxygen saturation (SpO2 is 90 to 93% with an intermittent review of the correlation between SpO2 and the partial pressure of arterial oxygen tension (PaO2. Because optimal oxygenation depends on individuals at the bedside making ongoing adjustments, each unit must define an optimal target range and set alarm limits according to their own equipment or conditions. All staff must be aware of these values and adjust the concentration of supplemental oxygen frequently.

Coupled thermo-hydro-mechanical calculations of the water saturation phase of a KBS-3 deposition hole. Influence of hydraulic rock properties on the water saturation phase

International Nuclear Information System (INIS)

Boergesson, Lennart; Hernelind, J.

1999-12-01

The wetting process in deposition holes designed according to the KBS-3-concept has been simulated with finite element calculations of the thermo-hydro-mechanical processes in the buffer, backfill and surrounding rock. The buffer material has been modelled according to the preliminary material models developed for swelling clay. The properties of the rock have been varied in order to investigate the influence of the rock properties and the hydraulic conditions on the wetting processes. In the modelling of the test holes the permeability of the rock matrix, the water supply from the backfill, the water pressure in the surrounding rock, the permeability of the disturbed zone around the deposition hole, the water retention properties of the rock, and the transmissivity of two fractures intersecting the deposition hole have been varied. The calculations indicate that the wetting takes about 5 years if the water pressure in the rock is high and if the permeability of the rock is so high that the properties of the bentonite determine the wetting rate. However, it may take considerably more than 30 years if the rock is very tight and the water pressure in the rock is low. The calculations also show that the influence of the rock structure is rather large except for the influence of the transmissivity T of the fractures, which turned out to be insignificant for the values used in the calculations

Gluon saturation in a saturated environment

International Nuclear Information System (INIS)

Kopeliovich, B. Z.; Potashnikova, I. K.; Schmidt, Ivan

2011-01-01

A bootstrap equation for self-quenched gluon shadowing leads to a reduced magnitude of broadening for partons propagating through a nucleus. Saturation of small-x gluons in a nucleus, which has the form of transverse momentum broadening of projectile gluons in pA collisions in the nuclear rest frame, leads to a modification of the parton distribution functions in the beam compared with pp collisions. In nucleus-nucleus collisions all participating nucleons acquire enhanced gluon density at small x, which boosts further the saturation scale. Solution of the reciprocity equations for central collisions of two heavy nuclei demonstrate a significant, up to several times, enhancement of Q sA 2 , in AA compared with pA collisions.

The influence of soil water status on Oryza Sativa Var. MR220 in KADA rice agroecosystem

International Nuclear Information System (INIS)

Nashriyah Mat; Ismail Che Haron; Mazleha Maskin; Mohd Razi Ismail

2006-01-01

A study to determine the influence of soil water status on rice plant Oryza sativa var. MR220 after panicle initiation stage was carried out at Ladang Merdeka Mulong Lating in the Kemubu Agricultural Development Authority (KADA) area, Kelantan. Five water management treatments imposed on direct seeded rice were; T1. Continuous flooding, T2. Early flooding up to panicle initiation stage followed by saturated (F55-saturated), T3. Early flooding for the first month followed by saturated (F-30 saturated), T4. Continuous saturated, and T5. Continuous field capacity condition throughout the growth stage. The treatments were arranged in Randomized Complete Block Design (RCBD) with four replicates. Results showed significant differences in soil moisture content in the order of T1>T2>T3>T4>T5. Significant differences were also observed in rice plant water content at 68 DAS (days after seeding) in the order of T2>T3>T4>T1>T5. Moisture content also showed significant differences between replicates in the order of R1>R2>R3>R4 and R2>R1>R3>R4; in rice plant and ricefield soil, respectively. Results however showed no significant difference in leaf stomatal conductance due to water stress. Rice plant moisture, soil moisture and leaf stomatal conductance showed no interaction. Published results show that even though overall crop yield was reduced by sheath blight and panicle blast incidence that occur at later stage in 2004-2005 field trials, highest grain yields were obtained from T2 (off season) and T4 (main season). Saturated condition seems to be the most suitable method of growing rice under minimal water input in KADA rice agroecosystem. (Author)

Lipid order, saturation and surface property relationships: a study of human meibum saturation.

Science.gov (United States)

Mudgil, Poonam; Borchman, Douglas; Yappert, Marta C; Duran, Diana; Cox, Gregory W; Smith, Ryan J; Bhola, Rahul; Dennis, Gary R; Whitehall, John S

2013-11-01

Tear film stability decreases with age however the cause(s) of the instability are speculative. Perhaps the more saturated meibum from infants may contribute to tear film stability. The meibum lipid phase transition temperature and lipid hydrocarbon chain order at physiological temperature (33 °C) decrease with increasing age. It is reasonable that stronger lipid-lipid interactions could stabilize the tear film since these interactions must be broken for tear break up to occur. In this study, meibum from a pool of adult donors was saturated catalytically. The influence of saturation on meibum hydrocarbon chain order was determined by infrared spectroscopy. Meibum is in an anhydrous state in the meibomian glands and on the surface of the eyelid. The influence of saturation on the surface properties of meibum was determined using Langmuir trough technology. Saturation of native human meibum did not change the minimum or maximum values of hydrocarbon chain order so at temperatures far above or below the phase transition of human meibum, saturation does not play a role in ordering or disordering the lipid hydrocarbon chains. Saturation did increase the phase transition temperature in human meibum by over 20 °C, a relatively high amount. Surface pressure-area studies showing the late take off and higher maximum surface pressure of saturated meibum compared to native meibum suggest that the saturated meibum film is quite molecularly ordered (stiff molecular arrangement) and elastic (molecules are able to rearrange during compression and expansion) compared with native meibum films which are more fluid agreeing with the infrared spectroscopic results of this study. In saturated meibum, the formation of compacted ordered islands of lipids above the surfactant layer would be expected to decrease the rate of evaporation compared to fluid and more loosely packed native meibum. Higher surface pressure observed with films of saturated meibum compared to native meibum

Effect of oxygen fugacity on OH dissolution in olivine under peridotite-saturated conditions: An experimental study at 1.5-7 GPa and 1100-1300 °C

Science.gov (United States)

Yang, Xiaozhi

2016-01-01

The dissolution of OH in olivine by experimental studies at simulated conditions has attracted increasing interest over the past three decades, and the influence of pressure, temperature and composition has been relatively well constrained. Oxygen fugacity is highly heterogeneous in the upper mantle, on both temporal and spatial scales, and is an important parameter in characterizing many chemical and physical processes in the mantle. However, less attention has been devoted to the effect of oxygen fugacity on OH dissolution in olivine, and the only few available reports on this topic have led to significant inconsistency and debate. In this study, the correlation between oxygen fugacity and OH solubility in Fe-bearing olivine has been systematically investigated by conducting experiments at 1.5-7 GPa and 1100-1300 °C and under peridotite- and fluid-saturated conditions, with natural gem-quality olivine single crystals and fresh peridotite xenoliths as starting materials and with oxygen fugacity controlled by the Fe-FeO, Ni-NiO and Fe2O3-Fe3O4 oxygen buffer pairs. The water concentrations were determined by polarized analyses using a Fourier-transform infrared spectroscopy. The results show that, at all the experimental conditions, the OH bands at both high frequency (∼3650-3450 cm-1) and low frequency (∼3450-3100 cm-1) are prominent. The intensity of OH bands at ∼3355 and 3325 cm-1 increases positively with oxygen fugacity, suggesting a dominant role of Fe3+ in their incorporation. Under otherwise identical conditions, the water content is gradually enhanced with increasing pressure, temperature or oxygen fugacity. The effect of oxygen fugacity on the enhancement of OH solubility appears not sensitive to temperature (1100-1300 °C) at a given pressure, but becomes progressively stronger with increasing pressure from 1.5 to 7 GPa given the temperature. Relative to oxygen fugacity buffers, the OH solubility is on average increased by ∼50% between Fe-FeO and

Determination of saturation functions and wettability for chalk based on measured fluid saturations

Energy Technology Data Exchange (ETDEWEB)

Olsen, D.; Bech, N.; Moeller Nielsen, C.

1998-08-01

The end effect of displacement experiments on low permeable porous media is used for determination of relative permeability functions and capillary pressure functions. Saturation functions for a drainage process are determined from a primary drainage experiment. A reversal of the flooding direction creates an intrinsic imbibition process in the sample, which enables determination if imbibition saturation functions. The saturation functions are determined by a parameter estimation technique. Scanning effects are modelled by the method of Killough. Saturation profiles are determined by NMR. (au)

Modelling suction instabilities in soils at varying degrees of saturation

Directory of Open Access Journals (Sweden)

Buscarnera Giuseppe

2016-01-01

Full Text Available Wetting paths imparted by the natural environment and/or human activities affect the state of soils in the near-surface, promoting transitions across different regimes of saturation. This paper discusses a set of techniques aimed at quantifying the role of hydrologic processes on the hydro-mechanical stability of soil specimens subjected to saturation events. Emphasis is given to the mechanical conditions leading to coupled flow/deformation instabilities. For this purpose, energy balance arguments for three-phase systems are used to derive second-order work expressions applicable to various regimes of saturation. Controllability analyses are then performed to relate such work input with constitutive singularities that reflect the loss of strength under coupled and/or uncoupled hydro-mechanical forcing. A suction-dependent plastic model is finally used to track the evolution of stability conditions in samples subjected to wetting, thus quantifying the growth of the potential for coupled failure modes upon increasing degree of saturation. These findings are eventually linked with the properties of the field equations that govern pore pressure transients, thus disclosing a conceptual link between the onset of coupled hydro-mechanical failures and the evolution of suction with time. Such results point out that mathematical instabilities caused by a non-linear suction dependent behaviour play an important role in the advanced constitutive and/or numerical tools that are commonly used for the analysis of geomechanical problems in the unsaturated zone, and further stress that the relation between suction transients and soil deformations is a key factor for the interpretation of runaway failures caused by intense saturation events.

Saturation and nucleation in hot nuclear systems

International Nuclear Information System (INIS)

Deangelis, A.R.

1990-07-01

We investigate nuclear fragmentation in a supersaturated system using classical nucleation theory. This allows us to go outside the normally applied constraint of chemical equilibrium. The system is governed by a virial equation of state, which we use to find an expression for the density as a function of pressure and temperature. The evolution of the system is discussed in terms of the phase diagram. Corrections are included to account for the droplet surface and all charges contained in the system. Using this model we investigate and discuss the effects of temperature and saturation, and compare the results to those of other models of fragmentation. We also discuss the limiting temperatures of the system for the cases with and without chemical equilibrium. We find that large nuclei will be formed in saturated systems, even above the limiting temperature as previously defined. We also find that saturation and temperature dominate surface and Coulomb effects. The effects are quite large, thus even a qualitative inspection of the yields may give an indication of the conditions during fragmentation

[Models for quantification of fluid saturation in two-phase flow system by light transmission method and its application].

Science.gov (United States)

Zhang, Yan-Hong; Ye, Shu-Jun; Wu, Ji-Chun

2014-06-01

Based on light transmission method in quantification of liquid saturation and its application in two-phase flow system, two groups of sandbox experiments were set up to study the migration of gas or Dense Non-Aqueous Phase Liquids (DNAPLs) in water saturated porous media. The migration of gas or DNAPL was monitored in the study. Two modified Light Intensity-Saturation (LIS) models for water/gas two-phase system were applied and verified by the experiment data. Moreover two new LIS models for NAPL/water system were developed and applied to simulate the DNAPL infiltration experiment data. The gas injection experiment showed that gas moved upward to the top of the sandbox in the form of 'fingering' and finally formed continuous distribution. The results of DNAPL infiltration experiment showed that TCE mainly moved downward as the result of its gravity, eventually formed irregular plume and accumulated at the bottom of the sandbox. The outcomes of two LIS models for water/gas system (WG-A and WG-B) were consistent to the measured data. The results of two LIS models for NAPL/water system (NW-A and NW-B) fit well with the observations, and Model NW-A based on assumption of individual drainage gave better results. It could be a useful reference for quantification of NAPL/water saturation in porous media system.

Improvement of chemical shift selective saturation (CHESS) pulse for MR angiography

International Nuclear Information System (INIS)

Ishimori, Yoshiyuki; Sashie, Hiroyuki; Hiraga, Akira; Matsuda, Tsuyoshi

2000-01-01

We improved the fat suppression technique based on chemical shift selective saturation (CHESS). To do this, we shortened the duration of the CHESS pulse to achieve a short repetition time (TR) for MR angiography (MRA). A short-duration CHESS pulse causes broad frequency band saturation, creating extensive offset from the resonance frequency of water. In our phantom experiment, the best parameters of the short-duration CHESS pulse were 3.84 ms in duration, -650 Hz in offset frequency from water resonance, and had a 130-degree flip angle. With this technique, MRA will be able to be carried out without a significant increase in TR. Thus, better vessel contrast will be maintained in time-of-flight (TOF) MRA or contrast-enhanced MRA when using the maximum intensity projection (MIP) method. (author)

Ocean acidification and calcium carbonate saturation states in the coastal zone of the West Antarctic Peninsula

NARCIS (Netherlands)

Jones, Elizabeth M.; Fenton, Mairi; Meredith, Michael P.; Clargo, Nicola M.; Ossebaar, Sharyn; Ducklow, Hugh W.; Venables, Hugh J.; de Baar, Henricus

The polar oceans are particularly vulnerable to ocean acidification; the lowering of seawater pH and carbonate mineral saturation states due to uptake of atmospheric carbon dioxide (CO2). High spatial variability in surface water pH and saturation states (Omega) for two biologically-important

Calculation of heat exchangers with saturated and underheated superfluid helium (He-2)

International Nuclear Information System (INIS)

Belyakov, V.P.; Shaposhnikov, V.A.; Budrik, V.V.; Volkova, N.M.

1986-01-01

Calculation technique for heat exchangers with saturated and underheated He-2 under conditions of natural inner convection and forced convection is delivered. The following variants of heat exchangers are considered: inside the bath with saturated He-2 a tube is placed along which subcooled He-2 flow moves with a constant rate; inside the bath with subcooled He-2 a tube is placed both ends of which are in the bath with saturated He-2; inside the bath with saturated He-2 a tube is placed both ends of which are in the bath with subcooled He-2. For all cases examples of calculation and experimental data of heat exchanger tests are presented. The developed methods of calculation of heat exchangers for saturated He-2 and subcooled He-2 make it possible to design and create superfluid helium cryostatting systems

42 CFR 494.40 - Condition: Water and dialysate quality.

Science.gov (United States)

2010-10-01

... demonstrate the following: (a) Standard: Water purity. Water and equipment used for dialysis meets the water... Boulevard, Suite 400, Arlington, VA 22201-4598. (b) Standard: Chlorine/chloramines. (1) The water treatment... 42 Public Health 5 2010-10-01 2010-10-01 false Condition: Water and dialysate quality. 494.40...

The role of hillslope topography on shallow landslides activation and basin saturation propensity

Science.gov (United States)

Lanni, C.; Pretto, I.; Rigon, R.

2009-12-01

Shallow Landslides are one of the most important causes of loss of human life and socio-economic damage related to the hydro-geological risk issues. In the past years a big number of researches have developed tools to assess for the stability condition of hillslopes at the basin-scale. Montgomery and Dietrich (1994), for instance, with their own SHALSTAB model, give a simple way to evaluate the safety factor of mountain hillslopes, coupling the infinite slope stability model with a very simple steady-state hydrological model based on the work by O'Loughlin (1986) and which has similarities to TOPOG (Beven and Kirkby, 1979). The state of art gives the possibility to evaluate the transient nature of the generated pore-pressure fields within soil-thickness during and after the rainfalls. A valuable tool to fulfill this purpose may be the GEOtop model (Rigon et al., 2006) born to solve the 3-dimensional form of Richards’ equation. The present work, which was held using GEOtop model, investigates the stability conditions and the water table level of nine characteristic hillslope types when steady-state conditions are reached. The artificial simple basins are created combining three different curvature's profile (straight, concave and convex) and three different plan shapes (parallel, convergent and divergent) (fig.1). In the analysis the hillslope soil thickness is imposed constant, while the bedrock is considered impermeable. Different intensity rainfalls are simulated. The results show that in the case of the lowest intensity rainfall, basins with convex shape present higher percentage of saturated area than concave and straight ones. Also, convergent hillslopes generally produce a higher percentage of saturated area than the other plan shapes. Moreover, in the case of higher intensity rainfalls, the concave profile curvature seems to be the first order controller on the saturation process. Regarding the stability conditions, convergent hillslopes generally presents

Seismic response analysis of the deep saturated soil deposits in Shanghai

Science.gov (United States)

Huang, Yu; Ye, Weimin; Chen, Zhuchang

2009-01-01

The quaternary deposits in Shanghai are horizontal soil layers of thickness up to about 280 m in the urban area with an annual groundwater table between 0.5 and 0.7 m from the surface. The characteristics of deep saturated deposits may have important influences upon seismic response of the ground in Shanghai. Based on the Biot theory for porous media, the water-saturated soil deposits are modeled as a two-phase porous system consisting of solid and fluid phases, in this paper. A nonlinear constitutive model for predicting the seismic response of the ground is developed to describe the dynamic characters of the deep-saturated soil deposits in Shanghai. Subsequently, the seismic response of a typical site with 280 m deep soil layers, which is subjected to four base excitations (El Centro, Taft, Sunan, and Tangshan earthquakes), is analyzed in terms of an effective stress-based finite element method with the proposed constitutive model. Special emphasis is given to the computed results of accelerations, excess pore-water pressures, and settlements during the seismic excitations. It has been found that the analysis can capture fundamental aspects of the ground response and produce preliminary results for seismic assessment.

Update report on fracture flow in saturated tuff: Dynamic transport task for the Nevada Nuclear Waste Investigations

International Nuclear Information System (INIS)

Janecky, D.R.; Rundberg, R.S.; Ott, M.; Mitchell, A.

1990-11-01

This report summarizes the results of continuing experiments on the behavior of tracers during fracture flow in saturated, welded tuff. These experiments were completed during the past year as part of the Dynamic Transport Task of geochemical investigations for the Yucca Mountain Project sponsored by the US Department of Energy. These experiments are designed to investigate the effects of fluid movement in fractures when coupled with matrix diffusion and sorption but isolated from the effects of capillary suction and two-phase flow characteristic of unsaturated conditions. The experiments reported here are continuations of experimental efforts reported previously. The behavior of three tracers [HTO (tritiated water), TcO 4 - (pertechnetate), and sulforhodamine B dye] have been investigated during flow through a saturated column of densely welded tuff from the Topopah Spring Member of the Paintbrush Tuff, Yucca Mountain, Nye County, southern Nevada. 31 refs., 26 figs., 2 tabs

Porewater Chemistry in Compacted Re-Saturated MX-80 Bentonite: Physico-Chemical Characterisation and Geochemical Modelling

International Nuclear Information System (INIS)

Bradbury, M. H.; Baeyens, B.

2002-06-01

Bentonites of various types are being investigated in many countries as backfill materials in high-level radioactive waste disposal concepts. Being able to understand the chemistry of the pore water in compacted bentonite, and the factors which influence it, is critical to the synthesis of sorption data bases and to predicting radionuclide solubilities, and hence to repository safety studies. However, quantification of the water chemistry in compacted bentonite is difficult because reliable samples for chemical analysis cannot be obtained even by squeezing at exceedingly high pressures. In this report concepts are developed which are somewhat different from those used in previously published works on bentonite pore water. Considerations of the swelling properties of montmorillonite led to the proposition that there were, generally speaking, three types of water associated with re-saturated compacted bentonite. The water defined as the pore water is only a small fraction of the total. The pore water volume present in re-saturated bentonites having different initial dry densities was quantified using CI- 'through diffusion' data. Highly compacted bentonite is considered to function as an efficient semi-permeable membrane so that re-saturation involves predominantly the movement of water molecules and not solute molecules. This implies that the composition of the external saturating aqueous phase is a second order effect. Consequently CI- concentrations in the pore water could be calculated from the deduced pore water volume values and the measured CI- inventory. The pH of the pore water of a compacted bentonite is an extremely important parameter because of its influence on radionuclide solubility and sorption. Arguments are presented in support of the thesis that the initial pH is fixed by the high buffering capacity afforded by the amphoteric =SOH sites. The pH of the pore water depends directly on the speciation of these sites i.e. the proportions of sites present

Ocean acidification and calcium carbonate saturation states in the coastal zone of the West Antarctic Peninsula

NARCIS (Netherlands)

Jones, E.M.; Fenton, M.; Meredith, M.P.; Clargo, N.M.; Ossebaar, S.; Ducklow, H.W.; Venables, H.J.; De Baar, H.J.W.

2017-01-01

The polar oceans are particularly vulnerable to ocean acidification; the lowering of seawater pH and carbonate mineral saturation states due to uptake of atmospheric carbon dioxide (CO2). High spatial variability in surface water pH and saturation states (Ω) for two biologically-important calcium

Oxidation of trichloroethylene, toluene, and ethanol vapors by a partially saturated permeable reactive barrier

Science.gov (United States)

Mahmoodlu, Mojtaba G.; Hassanizadeh, S. Majid; Hartog, Niels; Raoof, Amir

2014-08-01

The mitigation of volatile organic compound (VOC) vapors in the unsaturated zone largely relies on the active removal of vapor by ventilation. In this study we considered an alternative method involving the use of solid potassium permanganate to create a horizontal permeable reactive barrier for oxidizing VOC vapors. Column experiments were carried out to investigate the oxidation of trichloroethylene (TCE), toluene, and ethanol vapors using a partially saturated mixture of potassium permanganate and sand grains. Results showed a significant removal of VOC vapors due to the oxidation. We found that water saturation has a major effect on the removal capacity of the permeable reactive layer. We observed a high removal efficiency and reactivity of potassium permanganate for all target compounds at the highest water saturation (Sw = 0.6). A change in pH within the reactive layer reduced oxidation rate of VOCs. The use of carbonate minerals increased the reactivity of potassium permanganate during the oxidation of TCE vapor by buffering the pH. Reactive transport of VOC vapors diffusing through the permeable reactive layer was modeled, including the pH effect on the oxidation rates. The model accurately described the observed breakthrough curve of TCE and toluene vapors in the headspace of the column. However, miscibility of ethanol in water in combination with produced water during oxidation made the modeling results less accurate for ethanol. A linear relationship was found between total oxidized mass of VOC vapors per unit volume of permeable reactive layer and initial water saturation. This behavior indicates that pH changes control the overall reactivity and longevity of the permeable reactive layer during oxidation of VOCs. The results suggest that field application of a horizontal permeable reactive barrier can be a viable technology against upward migration of VOC vapors through the unsaturated zone.

Correcting human heart 31P NMR spectra for partial saturation. Evidence that saturation factors for PCr/ATP are homogeneous in normal and disease states

Science.gov (United States)

Bottomley, Paul A.; Hardy, Christopher J.; Weiss, Robert G.

Heart PCr/ATP ratios measured from spatially localized 31P NMR spectra can be corrected for partial saturation effects using saturation factors derived from unlocalized chest surface-coil spectra acquired at the heart rate and approximate Ernst angle for phosphor creatine (PCr) and again under fully relaxed conditions during each 31P exam. To validate this approach in studies of normal and disease states where the possibility of heterogeneity in metabolite T1 values between both chest muscle and heart and normal and disease states exists, the properties of saturation factors for metabolite ratios were investigated theoretically under conditions applicable in typical cardiac spectroscopy exams and empirically using data from 82 cardiac 31P exams in six study groups comprising normal controls ( n = 19) and patients with dilated ( n = 20) and hypertrophic ( n = 5) cardiomyopathy, coronary artery disease ( n = 16), heart transplants ( n = 19), and valvular heart disease ( n = 3). When TR ≪ T1,(PCr), with T1(PCr) ⩾ T1(ATP), the saturation factor for PCr/ATP lies in the range 1.5 ± 0.5, regardless of the T1 values. The precise value depends on the ratio of metabolite T1 values rather than their absolute values and is insensitive to modest changes in TR. Published data suggest that the metabolite T1 ratio is the same in heart and muscle. Our empirical data reveal that the saturation factors do not vary significantly with disease state, nor with the relative fractions of muscle and heart contributing to the chest surface-coil spectra. Also, the corrected myocardial PCr/ATP ratios in each normal or disease state bear no correlation with the corresponding saturation factors nor the fraction of muscle in the unlocalized chest spectra. However, application of the saturation correction (mean value, 1.36 ± 0.03 SE) significantly reduced scatter in myocardial PCr/ATP data by 14 ± 11% (SD) ( p ⩽ 0.05). The findings suggest that the relative T1 values of PCr and ATP are

A Conditionally Stable Scheme for a Transient Flow of a Non-Newtonian Fluid Saturating a Porous Medium

KAUST Repository

El-Amin, Mohamed

2012-06-02

The problem of thermal dispersion effects on unsteady free convection from an isothermal horizontal circular cylinder to a non-Newtonian fluid saturating a porous medium is examined numerically. The Darcy-Brinkman-Forchheimer model is employed to describe the flow field. The thermal diffusivity coefficient has been assumed to be the sum of the molecular diffusivity and the dynamic diffusivity due to mechanical dispersion. The simultaneous development of the momentum and thermal boundary layers are obtained by using finite difference method. The stability conditions are determined for each difference equation. Using an explicit finite difference scheme, solutions at each time-step have been found and then stepped forward in time until reaching steady state solution. Velocity and temperature profiles are shown graphically. It is found that as time approaches infinity, the values of friction factor and heat transfer coefficient approach the steady state values.

A Conditionally Stable Scheme for a Transient Flow of a Non-Newtonian Fluid Saturating a Porous Medium

KAUST Repository

El-Amin, Mohamed; Salama, Amgad; Sun, Shuyu

2012-01-01

The problem of thermal dispersion effects on unsteady free convection from an isothermal horizontal circular cylinder to a non-Newtonian fluid saturating a porous medium is examined numerically. The Darcy-Brinkman-Forchheimer model is employed to describe the flow field. The thermal diffusivity coefficient has been assumed to be the sum of the molecular diffusivity and the dynamic diffusivity due to mechanical dispersion. The simultaneous development of the momentum and thermal boundary layers are obtained by using finite difference method. The stability conditions are determined for each difference equation. Using an explicit finite difference scheme, solutions at each time-step have been found and then stepped forward in time until reaching steady state solution. Velocity and temperature profiles are shown graphically. It is found that as time approaches infinity, the values of friction factor and heat transfer coefficient approach the steady state values.

Localized corrosion of carbon steel in a CO{sub 2}-saturated oilfield formation water

Energy Technology Data Exchange (ETDEWEB)

Zhang, G.A. [Department of Mechanical and Manufacturing Engineering, University of Calgary, Calgary, AB, T2N 1N4 (Canada); Cheng, Y.F., E-mail: fcheng@ucalgary.c [Department of Mechanical and Manufacturing Engineering, University of Calgary, Calgary, AB, T2N 1N4 (Canada)

2011-01-01

In this work, corrosion and localized corrosion behavior of X65 pipeline steel were studied in a simulated, CO{sub 2}-saturated oilfield formation water by various electrochemical measurement techniques, including electrochemical impedance spectroscopy (EIS), potentiodynamic polarization curves, galvanic current and localized EIS (LEIS). The morphology and composition of the formed corrosion scale were characterized by scanning electron microscopy and energy-dispersive X-ray analysis. A conceptual model was developed to illustrate the occurrence of localized corrosion of the steel under scale. Both galvanic current and LEIS measurements showed that a galvanic effect existed between the bare steel and the scale-covered region. The scale-covered region served as cathode and the bare steel site as the anode. The big cathode vs. small anode geometry accelerated the local corrosion reaction. At an elevated temperature, a compact, crystalline scale was formed on the steel surface, enhancing the galvanic effect. Moreover, the stability of the scale was increased with time, and localized corrosion of the steel under scale experienced mechanistic changes with time.

Gas diffusion-derived tortuosity governs saturated hydraulic conductivity in sandy soils

DEFF Research Database (Denmark)

Masis Melendez, Federico; Deepagoda Thuduwe Kankanamge Kelum, Chamindu; de Jonge, Lis Wollesen

2014-01-01

Accurate prediction of saturated hydraulic conductivity (Ksat) is essential for the development of better distributed hydrological models and area-differentiated risk assessment of chemical leaching. The saturated hydraulic conductivity is often estimated from basic soil properties such as particle......, potential relationships between Ksat and Dp/Do were investigated. A total of 84 undisturbed soil cores were extracted from the topsoil of a field site, and Dp/Do and Ksat were measured in the laboratory. Water-induced and solids-induced tortuosity factors were obtained by applying a two-parameter Dp...

Effect of weightlessness on mineral saturation of bone tissue

Science.gov (United States)

Krasnykh, I. G.

1975-01-01

X-ray photometry of bone density established dynamic changes in mineral saturation of bone tissues for Soyuz spacecraft and Salyut orbital station crews. Calcaneus optical bone densities in all crew members fell below initial values; an increase in spacecrew exposure time to weightlessness conditions also increased the degree of decalcification. Demineralization under weightlessness conditions took place at a higher rate than under hypodynamia.

Effect of the hydrophilic and hydrophobic characteristics of the gas diffusion medium on polymer electrolyte fuel cell performance under non-humidification condition

International Nuclear Information System (INIS)

Park, Heesung

2014-01-01

Highlights: • GDM played significant role in the PEFC performance under dry condition. • Hydrophobicity of GDM affect the water condensation at the surface. • Optimum water saturation in the porous layer was between 0.1 and 0.3. - Abstract: Water is a significant component of polymer electrolyte fuel cells, affecting the proton conductivity in the membrane electrolyte. Therefore, polymer electrolyte fuel cells are generally operated with a humidifier to maintain a high relative humidity of the supplied gases; however, the humidifier contributes additional weight and cost. Although many studies have attempted to develop polymer electrolyte fuel cells without a humidifier, the studies have been mainly focused on the self-humidified membrane electrolyte and catalyst layer. In this paper, the author investigates the effect of polytetrafluoroethylene coated gas diffusion medium on the water content in the membrane electrolyte. The water condensation on the surfaces of the gas diffusion medium is visualised when the polymer electrolyte fuel cell is operated under non-humidification conditions. Numerical simulation suggests that the optimum water saturation is between 0.1 and 0.3 at the gas diffusion medium to hydrate the membrane electrolyte sufficiently without significantly blocking the diffused species under non-humidification conditions

Flashing oscillation in pool water

International Nuclear Information System (INIS)

Takamasa, Tomoji; Kondo, Koichi; Hazuku, Tatsuya

1996-01-01

This paper presents an experimental study of high-pressure saturated water discharging into the pool water. The purpose of the experiment is to clarify the phenomena that occur in blow-down of high-pressure saturated water from the pressure vessel into the water-filled containment in the case of a wall-crack accident or a LOCA in an advanced reactor. The results revealed that a flashing oscillation (FO) occurs when high-pressure saturated water discharges into the pool water, under specified experimental settings. The range of the flashing oscillates between a point very close to and some distance from the vent hole. The pressures in the vent tube and pool water vary according to the flashing oscillation. The pressure oscillation and frequency of flashing position might be caused by the balancing action between the supply of saturated water, flashing at the control volume and its condensation on the steam-water interface. A linear analysis was conducted using a spherical flashing bubble model. The period of the flashing oscillation in the experiments can be explained by theoretical analysis

Determination of Irreducible Water Saturation from nuclear magnetic resonance based on fractal theory — a case study of sandstone with complex pore structure

Science.gov (United States)

Peng, L.; Pan, H.; Ma, H.; Zhao, P.; Qin, R.; Deng, C.

2017-12-01

The irreducible water saturation (Swir) is a vital parameter for permeability prediction and original oil and gas estimation. However, the complex pore structure of the rocks makes the parameter difficult to be calculated from both laboratory and conventional well logging methods. In this study, an effective statistical method to predict Swir is derived directly from nuclear magnetic resonance (NMR) data based on fractal theory. The spectrum of transversal relaxation time (T2) is normally considered as an indicator of pore size distribution, and the micro- and meso-pore's fractal dimension in two specific range of T2 spectrum distribution are calculated. Based on the analysis of the fractal characteristics of 22 core samples, which were drilled from four boreholes of tight lithologic oil reservoirs of Ordos Basin in China, the positive correlation between Swir and porosity is derived. Afterwards a predicting model for Swir based on linear regressions of fractal dimensions is proposed. It reveals that the Swir is controlled by the pore size and the roughness of the pore. The reliability of this model is tested and an ideal consistency between predicted results and experimental data is found. This model is a reliable supplementary to predict the irreducible water saturation in the case that T2 cutoff value cannot be accurately determined.

Steam injection into water-saturated porous rock

NARCIS (Netherlands)

Bruining, J.; Marchesin, D.; Duijn, van C.J.

2003-01-01

We formulate conservation laws governing steam injection in a linear porous medium containing water. Heat losses to the outside are neglected. We find a complete and systematic description of all solutions of the Riemann problem for the injection of a mixture of steam and water into a

Thermal effects on water exclusion from a cavity in unsaturated tuff

International Nuclear Information System (INIS)

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

1992-01-01

For an unsaturated, fractured porous medium subjected to uniform infiltration, we analyze thermal effects on water exclusion from cavities. This is of practical interest in a nuclear waste repository. A crucial question is: How much infiltration will lead to heated cavity-rock interface in tunnels and drifts being saturated so that water can enter a cavity. The combination of cavity size, dimensionless temperature difference, and infiltration rate that will lead to the critical condition at the cavity apex; this calculation considers the tuff matrix only. Here, the large projection area of the cavity intercepts large amounts of infiltration, requiring a lesser critical infiltration rate to saturate the cavity apex

Match properties of heat transfer and coupled heat and mass transfer processes in air-conditioning system

International Nuclear Information System (INIS)

Zhang Tao; Liu Xiaohua; Zhang Lun; Jiang Yi

2012-01-01

Highlights: ► Investigates match properties of heat or mass transfer processes in HVAC system. ► Losses are caused by limited transfer ability, flow and parameter mismatching. ► Condition of flow matching is the same heat capacity of the fluids. ► Parameter matching is only reached along the saturation line in air–water system. ► Analytical solutions of heat and mass transfer resistance are derived. - Abstract: Sensible heat exchangers and coupled heat and mass transfer devices between humid air and water/desiccant are commonly used devices in air-conditioning systems. This paper focuses on the match properties of sensible heat transfer processes and coupled heat and mass transfer processes in an effort to understand the reasons for performance limitations in order to optimize system performance. Limited heat transfer capability and flow mismatching resulted in heat resistance of the sensible heat transfer process. Losses occurred during the heat and mass transfer processes due to limited transfer capability, flow mismatching, and parameter mismatching. Flow matching was achieved when the heat capacities of the fluids were identical, and parameter matching could only be reached along the saturation line in air–water systems or the iso-concentration line in air–desiccant systems. Analytical solutions of heat transfer resistance and mass transfer resistance were then derived. The heat and mass transfer process close to the saturation line is recommended, and heating sprayed water resulted in better humidification performance than heating inlet air in the air humidifier.

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.

Seismic analysis for shroud facility in-pile tube and saturated temperature capsules

International Nuclear Information System (INIS)

Iimura, Koichi; Yamaura, Takayuki; Ogawa, Mitsuhiro

2009-07-01

At Oarai Research and Development Center, Japan Atomic Energy Agency (JAEA), the plan of repairing and refurbishing Japan Materials Testing Reactor (JMTR) has progressed in order to restart JMTR operation in the fiscal 2011. As a part of effective use of JMTR, the neutron irradiation tests of LWR fuels and materials has been planned in order to study their soundness. By using Oarai Shroud Facility (OSF-1) and Fuel Irradiation Facility with the He-3 gas control system for power lamping test using Boiling Water Capsules (BOCA Irradiation Facility), the irradiation tests with power ramping will be carried out to study the soundness of fuel under LWR Transient condition. OSF-1 is the irradiation facility of shroud type that can insert and eject the capsule under reactor operation, and is composed of 'In-pile Tube', 'Cooling system' and 'Capsule exchange system'. BOCA Irradiation Facility is the facility which simulates irradiation environment of LWR, and is composed of 'Boiling water Capsule', 'Capsule control system' and 'Power control system by He-3'. By using Saturated temperature Capsules and the water environment control system, the material irradiation tests under the water chemistry condition of LWR will be carried out to clarify the mechanism of IASCC. In JMTR, these facilities are in service at the present. However, the detailed design for renewal or remodeling was carried out based on the new design condition in order to be correspondent to the irradiation test plan after restart JMTR operation. In this seismic analysis of the detailed design, each equipment classification and operating state were arranged with 'Japanese technical standards of the structure on nuclear facility for test research' and 'Technical guidelines for seismic design of nuclear power plants on current, and then, stress calculation and evaluation were carried out by FEM piping analysis code 'SAP' and structure analysis code 'ABAQUS'. About the stress of the seismic force, it was proven

Hydrologic mechanisms governing fluid flow in partially saturated, fractured, porous tuff at Yucca Mountain

International Nuclear Information System (INIS)

Wang, J.S.Y.; Narasimhan, T.N.

1984-10-01

In contrast to the saturated zone where fluid moves rapidly along fractures, the fractures (with apertures large relative to the size of matrix pores) will desaturate first during drainage process and the bulk of fluid flow would be through interconnected pores in the matrix. Within a partially drained fracture, the presence of a relatively continuous air phase will produce practically an infinite resistance to liquid flow in the direction parallel to the fracture. The residual liquid will be held by capillary force in regions around fracture contact areas where the apertures are small. Normal to the fracture surfaces, the drained portion of the fractures will reduce the effective area for liquid flow from one matrix block to another matrix block. A general statistical theory is constructed for flow along the fracture and for flow between the matrix blocks to the fractures under partially saturated conditions. Results are obtained from an aperture distribution model for fracture saturation, hydraulic conductivity, and effective matrix-fracture flow areas as functions of pressure. Drainage from a fractured tuff column is simulated. The parameters for the simulations are deduced from fracture surface characteristics, spacings and orientations based on core analyses, and from matrix characteristics curve based on laboratory measurements. From the cases simulated for the fractured, porous column with discrete vertical and horizontal fractures and porous matrix blocks explicitly taken into account, it is observed that the highly transient changes from fully saturated conditions to partially saturated conditions are extremely sensitive to the fracture properties. However, the quasi-steady changes of the fluid flow of a partially saturated, fractured, porous system could be approximately simulated without taking the fractures into account. 22 references, 16 figures

Properties of membranes to permeation to radon 222. New development for the measurement of radon 222 in water and water-saturated soils

International Nuclear Information System (INIS)

Labed, V.; Robe, M.C.

1992-01-01

Membranes that exclude water but are permeable to radon can extend the range of environments in which many radon detection systems could operate. We have studied the permeation of 222 Rn through membranes separating air and water phases. The permeation coefficients and the activation energy were calculated for various conditions. Potential applications such as in situ detection of radon in water are discussed

The Existing Regulatory Conditions for 'Energy Smart Water Utilities'

DEFF Research Database (Denmark)

Basse, Ellen Margrethe

2014-01-01

This chapter is focused on the legal conditions that exist for the energy–smart water utilities in the European Union (EU). In section 2 the interdependencies of water and energy services and the growing interest in solving these problems that may arise from this interdependence by regulatory ini...... legal design and the problems that it causes for the water utilities that want to be resource–efficient and have a low–carbon footprint.......This chapter is focused on the legal conditions that exist for the energy–smart water utilities in the European Union (EU). In section 2 the interdependencies of water and energy services and the growing interest in solving these problems that may arise from this interdependence by regulatory...... initiatives are shortly described. One of the solutions needed is a reduction of energy use in the water utilities by their utilisation of renewable sources – acting as energy–smart water utilities. Such utilities are described in section 3. The policy and law regulating the water utilities are important...

SURGTANK, Steam Pressure, Saturation Temperature or Reactor Surge Tank

International Nuclear Information System (INIS)

Gorman, D.J.; Gupta, R.K.

2001-01-01

1 - Description of problem or function: SURGTANK generates the steam pressure, saturation temperature, and ambient temperature history for a nuclear reactor steam surge tank (pressurizer) in a state of thermodynamic equilibrium subjected to a liquid insurge described by a specified time history of liquid levels. It is capable also of providing the pressure and saturation temperature history, starting from thermodynamic equilibrium conditions, for the same tank subjected to an out-surge described by a time history of liquid levels. Both operations are available for light- or heavy- water nuclear reactor systems. The tank is assumed to have perfect thermal insulation on its outer wall surfaces. 2 - Method of solution: Surge tank geometry and initial liquid level and saturation pressure are provided as input for the out-surge problem, along with the prescribed time-sequence level history. SURGTANK assumes a reduced pressure for the end of the first change in liquid level and determines the associated change of entropy for the closed system. The assumed pressure is adjusted and the associated change in entropy recalculated until a pressure is attained for which no change occurs. This pressure is recorded and used as the beginning pressure for the next level increment. The system is then re-defined to exclude the small amount of liquid which has left the tank, and a solution for the pressure at the end of the second level increment is obtained. The procedure is terminated when the pressure at the end of the final increment has been determined. Surge tank geometry, thermal conductivity, specific heat, and density of tank walls, initial liquid level, and saturation pressure are provided as input for the insurge problem, along with the prescribed time-sequence level history. SURGTANK assumes a slightly in- creased pressure for the end of the first level, the inner tank sur- face is assumed to follow saturation temperature, linearly with time, throughout the interval, and

Comparison of mass transport using average and transient rainfall boundary conditions

International Nuclear Information System (INIS)

Duguid, J.O.; Reeves, M.

1976-01-01

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

Femoral venous oxygen saturation is no surrogate for central venous oxygen saturation

NARCIS (Netherlands)

van Beest, Paul A.; van der Schors, Alice; Liefers, Henriëtte; Coenen, Ludo G. J.; Braam, Richard L.; Habib, Najib; Braber, Annemarije; Scheeren, Thomas W. L.; Kuiper, Michaël A.; Spronk, Peter E.

2012-01-01

Objective: The purpose of our study was to determine if central venous oxygen saturation and femoral venous oxygen saturation can be used interchangeably during surgery and in critically ill patients. Design: Prospective observational controlled study. Setting: Nonacademic university-affiliated

Effective stress principle for partially saturated media

International Nuclear Information System (INIS)

McTigue, D.F.; Wilson, R.K.; Nunziato, J.W.

1984-04-01

In support of the Nevada Nuclear Waste Storage Investigation (NNWSI) Project, we have undertaken a fundamental study of water migration in partially saturated media. One aspect of that study, on which we report here, has been to use the continuum theory of mixtures to extend the classical notion of effective stress to partially saturated media. Our analysis recovers previously proposed phenomenological representations for the effective stress in terms of the capillary pressure. The theory is illustrated by specializing to the case of linear poroelasticity, for which we calculate the deformation due to the fluid pressure in a static capillary fringe. We then examine the transient consolidation associated with liquid flow induced by an applied surface load. Settlement accompanies this flow as the liquid is redistributed by a nonlinear diffusion process. For material properties characteristic of tuff from the Nevada Test Site, these effects are found to be vanishingly small. 14 references, 7 figures, 1 table

Well-logging method using well-logging tools run through a drill stem test string for determining in-situ change in formation water saturation values

International Nuclear Information System (INIS)

Fertl, W.H.

1975-01-01

A logging tool (pulsed neutron or neutron-gamma ray) whose response indicates formation water saturation value, is run through an opening extending through a portion of a drill stem test string. A sample portion of the formation fluid in the zone of interest is removed and another logging run is made. The differences between the plots of the two logging runs indicate the formation potential productivity in the zone of interest

Modified LMI condition for the realization of limit cycle-free digital filters using saturation arithmetic

International Nuclear Information System (INIS)

Singh, Vimal

2007-01-01

A criterion in the form of linear matrix inequality for the elimination of limit cycles in a class of state-space digital filters using saturation arithmetic is presented. The criterion is a modified form of a previously reported criterion

Transport of gadolinium- and arsenic-based pharmaceuticals in saturated soil under various redox conditions.

Science.gov (United States)

Menahem, Adi; Dror, Ishai; Berkowitz, Brian

2016-02-01

The release of pharmaceuticals and personal care products (PPCPs) to the soil-water environment necessitates understanding of PPCP transport behavior under conditions that account for dynamic flow and varying redox states. This study investigates the transport of two organometallic PPCPs, Gd-DTPA and roxarsone (arsenic compound) and their metal salts (Gd(NO3)3, AsNaO2); Gd-DTPA is used widely as a contrasting agent for MRI, while roxarsone is applied extensively as a food additive in the broiler poultry industry. Here, we present column experiments using sand and Mediterranean red sandy clay soil, performed under several redox conditions. The metal salts were almost completely immobile. In contrast, transport of Gd-DTPA and roxarsone was affected by the soil type. Roxarsone was also affected by the different redox conditions, showing delayed breakthrough curves as the redox potential became more negative due to biological activity (chemically-strong reducing conditions did not affect the transport). Mechanisms that include adsorptive retardation for aerobic and nitrate-reducing conditions, and non-adsorptive retardation for iron-reducing, sulfate-reducing and biologically-strong reducing conditions, are suggested to explain the roxarsone behavior. Gd-DTPA is found to be a stable complex, with potential for high mobility in groundwater systems, whereas roxarsone transport through groundwater systems is affected by redox environments, demonstrating high mobility under aerobic and nitrate-reducing conditions and delayed transport under iron-reducing, sulfate-reducing and biologically-strong reducing conditions. Copyright © 2015 Elsevier Ltd. All rights reserved.

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.

Environmental-assisted fatigue in austenitic stainless steels under light water reactor conditions

International Nuclear Information System (INIS)

Seifert, H.P.; Ritter, S.; Spaetig, P.

2015-01-01

The environmental-assisted fatigue (EAF) initiation and subsequent short crack growth behaviour of different austenitic stainless steels were characterised under simulated BWR/HWC and primary PWR conditions by cyclic fatigue tests with sharply notched fracture mechanics specimens. After a brief summary overview on the previous PSI observations, an update with new and preliminary results about the effect of pH, dissolved hydrogen, load ratio/mean stress, long static load hold times and load sequences is given in this paper. At low electrochemical corrosion potentials (ECP), the physical EAF initiation life moderately decreases with increasing dissolved hydrogen content and decreasing pH. Both parameters have little effect on the subsequent short EAF crack growth within the investigated range. Notch strain amplitude thresholds for environmental effects on physical EAF crack initiation decrease with increasing load ratio and mean stress. At small notch strain amplitudes, the effect of mean stress is more pronounced in BWR/HWC environment than in air and predicted by typical fatigue life mean stress corrections. Under certain loading conditions, long static load hold times result in an increase of the physical EAF initiation life, which saturates for very long hold times. On the other hand, little effect of hold times on subsequent stationary short EAF crack growth rates is observed. The physical EAF initiation life under load sequence loading in high-temperature water may be moderately shorter or significantly longer than predicted by a linear damage accumulation rule and corresponding constant load amplitude tests depending on the load history. (authors)

Firetube boiler with high efficiency for producing saturated or superheated steam

Energy Technology Data Exchange (ETDEWEB)

Carosso, V J; Carosso, J Y

1976-10-07

This boiler for producing saturated or super-heated steam is to be manufactured in one piece or in units which can be assembled at site without skilled workers, at the factory. It is to have a high efficiency and dimensions which permit the transport of the completely assembled boiler by road transport. The relatively small water-steam vessel lies across the longitudinal axis of the boiler in the rear boiler space over a battery of preheater tubes. By these measures and by a very detailed and appropriately described rational arrangement of other parts, such as convection bundles, primary and secondary superheater, evaporation tubes, which form an 'evaporation shield', upper and lower longitudinal chambers with vertical connecting pipes of different crossections, the above mentioned condition for space requirement is fulfilled and a high efficiency should be achieved, but with considerable expense.

Water transport in gas diffusion media for PEM fuel cells. Experimental and numerical investigation

Energy Technology Data Exchange (ETDEWEB)

Roth, Joerg

2010-08-20

The water flux in partially saturated hydrophobic carbon fibre paper for polymer electrolyte membrane fuel cell applications is investigated and compared with the frequently used constitutive two-phase flow model based on Darcy's law. Further, the first steps towards a math-based material design for gas diffusion media are explored in this thesis. Two self-developed ex-situ experiments to investigate the liquid water transport are introduced. The first is a newly developed buoyancy-based measurement of the pressuresaturation relationship on thin porous material with an accuracy of 0.5 kPa for the pressure and {+-} 5% for the saturation. The second experiment measures the pressure drop in dependence of flow rates down to magnitudes of {mu}L/s across the partially saturated thin porous material. This flow rate is relevant for the fuel cell application. The liquid water transport through Toray 060 carbon fibre paper, impregnated with 7% and 10% PTFE is investigated at wet and dry boundary conditions. The experiments are also accompanied by analytical and numerical free surface modelling with the consideration of the material morphology and liquid-solid interaction. The imbibing and draining cases of an arrangement of six fibres at varying solid-liquid interaction and boundary conditions are studied with 'Surface Evolver'. In order to evaluate the findings of ex-situ and modelling work for applicability to water transport in fuel cell operation, the technique of nuclear magnetic resonance (NMR) imaging is assessed. The focus is on the visualisation of 2D and 3D water distribution in the operating fuel cell. The compatibility of the NMR experiment with fuel cell operation in relation to material selection, operating temperature, and current density is addressed. NMR imaging is employed for different current densities, stoichiometries, and fuel cell arrangements. The fuel cell arrangements differ by the cathode diffusion medium. Plain, hydrophobic, and

Femoral venous oxygen saturation is no surrogate for central venous oxygen saturation

NARCIS (Netherlands)

van Beest, Paul A.; van der Schors, Alice; Liefers, Henriette; Coenen, Ludo G. J.; Braam, Richard L.; Habib, Najib; Braber, Annemarije; Scheeren, Thomas W. L.; Kuiper, Michael A.; Spronk, Peter E.

2012-01-01

Objective:  The purpose of our study was to determine if central venous oxygen saturation and femoral venous oxygen saturation can be used interchangeably during surgery and in critically ill patients. Design:  Prospective observational controlled study. Setting:  Nonacademic university-affiliated

Stabilization of Neutral Systems with Saturating Actuators

Directory of Open Access Journals (Sweden)

F. El Haoussi

2012-01-01

to determine stabilizing state-feedback controllers with large domain of attraction, expressed as linear matrix inequalities, readily implementable using available numerical tools and with tuning parameters that make possible to select the most adequate solution. These conditions are derived by using a Lyapunov-Krasovskii functional on the vertices of the polytopic description of the actuator saturations. Numerical examples demonstrate the effectiveness of the proposed technique.

Evaluation of Colloid Retention Site Dominance in Variably Saturated Porous Media: An All Pores Pore-Scale Analysis

Science.gov (United States)

Morales, Veronica; Perez-Reche, Francisco; Holzner, Markus; Kinzelbach, Wolfgang

2016-04-01

It is well accepted that colloid and nanoparticle transport processes in porous media differ substantially between water saturated and unsaturated conditions. Differences are frequently ascribed to particle immobilization by association with interfaces with the gas, as well as to restrictions of the liquid medium through which colloids are transported. Yet, the current understanding of the importance of particle retention at gas interfaces is based on observations of single pores or two-dimensional pore network representations, leaving open the question of their statistical significance when all pores in the medium are considered. In order to address this question, column experiments were performed using a model porous medium of glass beads through which Silver particles were transported for conditions of varying water content and water chemistry. X-ray microtomography was subsequently employed as a non-destructive imaging technique to obtain pore-scale information of the entire column regarding: i) the presence and distribution of the main locations where colloids can become retained (interfaces with the water-solid, air-water, air-solid, and air-water-solid, grain-grain contacts, and the bulk liquid), ii) deposition profiles of colloids along the column classified by the available retention location, and iii) channel widths of 3-dimensional pore-water network representations. The results presented provide a direct statistical evaluation on the significance of colloid retention by attachment to interfaces or by strainig at contact points where multiple interfaces meet.

Output feedback control of linear fractional transformation systems subject to actuator saturation

Science.gov (United States)

Ban, Xiaojun; Wu, Fen

2016-11-01

In this paper, the control problem for a class of linear parameter varying (LPV) plant subject to actuator saturation is investigated. For the saturated LPV plant depending on the scheduling parameters in linear fractional transformation (LFT) fashion, a gain-scheduled output feedback controller in the LFT form is designed to guarantee the stability of the closed-loop LPV system and provide optimised disturbance/error attenuation performance. By using the congruent transformation, the synthesis condition is formulated as a convex optimisation problem in terms of a finite number of LMIs for which efficient optimisation techniques are available. The nonlinear inverted pendulum problem is employed to demonstrate the effectiveness of the proposed approach. Moreover, the comparison between our LPV saturated approach with an existing linear saturated method reveals the advantage of the LPV controller when handling nonlinear plants.

Facilitated transport of copper with hydroxyapatite nanoparticles in saturated sand

Science.gov (United States)

Saturated packed column experiments were conducted to investigate the facilitated transport of Cu with hydroxyapatite nanoparticles (nHAP) at different pore water velocities (0.22-2.2 cm min–1), solution pH (6.2-9.0), and fraction of Fe oxide coating on grain surfaces (', 0-0.36). The facilitated tr...

Final report - Microbial pathways for the reduction of mercury in saturated subsurface sediments

Energy Technology Data Exchange (ETDEWEB)

Tamar barkay; Lily Young; Gerben Zylstra

2009-08-25

Mercury is a component of mixed wastes that have contaminated vast areas of the deep subsurface as a result of nuclear weapon and energy production. While this mercury is mostly bound to soil constituents episodes of groundwater contamination are known in some cases resulting in potable water super saturated with Hg(0). Microbial processes that reduce Hg(II) to the elemental form Hg(0) in the saturated subsurface sediments may contribute to this problem. When we started the project, only one microbial pathway for the reduction of Hg(II), the one mediated by the mer operon in mercury resistant bacteria was known. As we had previously demonstrated that the mer mediated process occurred in highly contaminated environments (Schaefer et al., 2004), and mercury concentrations in the subsurface were reported to be low (Krabbenhoft and Babiarz, 1992), we hypothesized that other microbial processes might be active in reducing Hg(II) to Hg(0) in saturated subsurface environments. The specific goals of our projects were: (1) Investigating the potential for Hg(II) reduction under varying electron accepting conditions in subsurface sediments and relating these potential to mer gene distribution; and (2) Examining the physiological and biochemical characteristics of the interactions of anaerobic bacteria with mercury. The results are briefly summarized with references to published papers and manuscripts in preparation where details about our research can be found. Additional information may be found in copies of our published manuscripts and conference proceedings, and our yearly reports that were submitted through the RIMS system.

The influence of water saturation on mechanical properties of ceramic bricks – tests on 19th- century and contemporary bricks

Directory of Open Access Journals (Sweden)

Matysek, P.

2016-09-01

Full Text Available The paper presents test results concerning ceramic bricks produced in 1880’s. Bricks were obtained from a building erected as part of Archduke Rudolf barracks in Krakow. The tests helped to specify changes in brick compressive strength and hardness, caused by water saturation in the ceramic material. For comparison purposes, tests were also carried out on contemporary bricks. Tests showed that mechanical properties of the ceramic bricks in the water saturation state were worse than in the dry state. The impact of strong brick moisture on changes of mechanical parameters is essential in terms of safety assessment for brick structures.En el artículo se presentan los resultados del estudio de los ladrillos cerámicos producidos en los años 80 del siglo XIX. Los ladrillos se obtuvieron del edificio que forma parte de un conjunto de cuarteles del archiduque Rudolfo en Cracovia en Polonia. En los estudios se han determinado los cambios de la resistencia a la compresión y la dureza de los ladrillos, por efecto de la saturación de agua del material cerámico. A efectos comparativos, se han realizado también estudios de ladrillos producidos en la actualidad. Se ha comprobado que la saturación de agua de los ladrillos cerámicos lleva consigo una considerable disminución de las propiedades mecánicas. Por lo tanto, el impacto de la alta humedad de los ladrillos sobre el cambio de las propiedades mecánicas constituye un factor significativo en la evaluación de la seguridad en las construcciones de ladrillo.

On-bead combinatorial synthesis and imaging of chemical exchange saturation transfer magnetic resonance imaging agents to identify factors that influence water exchange.

Science.gov (United States)

Napolitano, Roberta; Soesbe, Todd C; De León-Rodríguez, Luis M; Sherry, A Dean; Udugamasooriya, D Gomika

2011-08-24

The sensitivity of magnetic resonance imaging (MRI) contrast agents is highly dependent on the rate of water exchange between the inner sphere of a paramagnetic ion and bulk water. Normally, identifying a paramagnetic complex that has optimal water exchange kinetics is done by synthesizing and testing one compound at a time. We report here a rapid, economical on-bead combinatorial synthesis of a library of imaging agents. Eighty different 1,4,7,10-tetraazacyclododecan-1,4,7,10-tetraacetic acid (DOTA)-tetraamide peptoid derivatives were prepared on beads using a variety of charged, uncharged but polar, hydrophobic, and variably sized primary amines. A single chemical exchange saturation transfer image of the on-bead library easily distinguished those compounds having the most favorable water exchange kinetics. This combinatorial approach will allow rapid screening of libraries of imaging agents to identify the chemical characteristics of a ligand that yield the most sensitive imaging agents. This technique could be automated and readily adapted to other types of MRI or magnetic resonance/positron emission tomography agents as well.

A Physically Based Analytical Model to Describe Effective Excess Charge for Streaming Potential Generation in Water Saturated Porous Media

Science.gov (United States)

Guarracino, L.; Jougnot, D.

2018-01-01

Among the different contributions generating self-potential, the streaming potential is of particular interest in hydrogeology for its sensitivity to water flow. Estimating water flux in porous media using streaming potential data relies on our capacity to understand, model, and upscale the electrokinetic coupling at the mineral-solution interface. Different approaches have been proposed to predict streaming potential generation in porous media. One of these approaches is the flux averaging which is based on determining the excess charge which is effectively dragged in the medium by water flow. In this study, we develop a physically based analytical model to predict the effective excess charge in saturated porous media using a flux-averaging approach in a bundle of capillary tubes with a fractal pore size distribution. The proposed model allows the determination of the effective excess charge as a function of pore water ionic concentration and hydrogeological parameters like porosity, permeability, and tortuosity. The new model has been successfully tested against different set of experimental data from the literature. One of the main findings of this study is the mechanistic explanation to the empirical dependence between the effective excess charge and the permeability that has been found by several researchers. The proposed model also highlights the link to other lithological properties, and it is able to reproduce the evolution of effective excess charge with electrolyte concentrations.

Experimental study and mechanical modelling of the effects of water-driving in an oil saturated chalk. Application to the petroleum industry; Etude experimentale et modelisation mecanique des effets du balayage a l'eau dans une craie saturee d'huile. Application a l'industrie petroliere

Energy Technology Data Exchange (ETDEWEB)

Mata, C.

2001-01-01

The production of hydrocarbons may sometimes lead to compaction of the oil-reservoir layers with substantial collapse of the soil surface; this mechanism is usually mentioned as Subsidence. Classical remedy to this problem is to sustain the fluid pressure with the help of water injection. However, in presence of high porosity chalk (porosity > 30%), this technique does not give effective results: the subsidence rate at North Sea reservoirs (Ekofisk field), after injection, has remained unchanged. Some justify the subsistence in the chalk as caused by phenomena of dissolution of the carbonates; others think it is connected to the destruction of capillary menisci. In this research, we follow this second approach. This study is finalized to a better understanding of the compaction mechanisms in pure carbonates when water is injected. This is done by proposing -in micro-scale first and in macro-scale after- a physical model that agrees with empirical observations. In order to meet this target, IFP skills and experience in physical and chemical measurements (taken before, after and during mechanical tests) have proficiently joined ENPC laboratory (CERMMO) knowledge of micro and macro modelling. The soft rock studied is a Paris basin's white chalk (Craie de Guerville). Its physical and chemical characterisation (i.e.: silica content, porosity, permeability) is very similar to North Sea chalk, but Guerville chalk has never been in contact with oil and generally it crops out of the ground surface. Strength parameters of this rock have been first determined by standard triaxial tests. Three different saturation configurations have been examined: dry, fully oil-saturated and fully water-saturated. As literature clearly state, dry chalk is stronger than oil saturated chalk and the first two are largely stronger than water saturated chalk. Therefore uniaxial strain water injection tests have been performed on oil saturated samples. Results, coupled with previous physical

Concentration and saturation effects of tethered polymer chains on adsorbing surfaces

Science.gov (United States)

Descas, Radu; Sommer, Jens-Uwe; Blumen, Alexander

2006-12-01

We consider end-grafted chains at an adsorbing surface under good solvent conditions using Monte Carlo simulations and scaling arguments. Grafting of chains allows us to fix the surface concentration and to study a wide range of surface concentrations from the undersaturated state of the surface up to the brushlike regime. The average extension of single chains in the direction parallel and perpendicular to the surface is analyzed using scaling arguments for the two-dimensional semidilute surface state according to Bouchaud and Daoud [J. Phys. (Paris) 48, 1991 (1987)]. We find good agreement with the scaling predictions for the scaling in the direction parallel to the surface and for surface concentrations much below the saturation concentration (dense packing of adsorption blobs). Increasing the grafting density we study the saturation effects and the oversaturation of the adsorption layer. In order to account for the effect of excluded volume on the adsorption free energy we introduce a new scaling variable related with the saturation concentration of the adsorption layer (saturation scaling). We show that the decrease of the single chain order parameter (the fraction of adsorbed monomers on the surface) with increasing concentration, being constant in the ideal semidilute surface state, is properly described by saturation scaling only. Furthermore, the simulation results for the chains' extension from higher surface concentrations up to the oversaturated state support the new scaling approach. The oversaturated state can be understood using a geometrical model which assumes a brushlike layer on top of a saturated adsorption layer. We provide evidence that adsorbed polymer layers are very sensitive to saturation effects, which start to influence the semidilute surface scaling even much below the saturation threshold.

Thermal conductivity coefficients of water and heavy water in the liquid state up to 3700C

International Nuclear Information System (INIS)

Le Neindre, B.; Bury, P.; Tufeu, R.; Vodar, B.

1976-01-01

The thermal conductivity coefficients of water and heavy water of 99.75 percent isotopic purity were measured using a coaxial cylinder apparatus, covering room temperature to their critical temperatures, and pressures from 1 to 500 bar for water, and from 1 to 1000 bar for heavy water. Following the behavior of the thermal conductivity coefficient of water, which shows a maximum close to 135 0 C, the thermal conductivity coefficient of heavy water exhibits a maximum near 95 0 C and near saturation pressures. This maximum is displaced to higher temperatures when the pressure is increased. Under the same temperature and pressure conditions the thermal conductivity coefficient of heavy water was lower than for water. The pressure effect was similar for water and heavy water. In the temperature range of our experiments, isotherms of thermal conductivity coefficients were almost linear functions of density

Study of the amplified spontaneous emission spectral width and gain coefficient for a KrF laser in unsaturated and saturated conditions

International Nuclear Information System (INIS)

Hariri, A; Sarikhani, S

2014-01-01

On the basis of a model of a geometrically dependent gain coefficient, the amplified spontaneous emission (ASE) spectral width was calculated analytically for the nearly resonant transition of ν ∼ ν 0 , and also numerically for a wide range of transition frequencies. For this purpose, the intensity rate equation was used under unsaturated and saturated conditions. For verifying the proposed model, reported measurements of the ASE energy versus the excitation length for a KrF laser were used. For the excitation length of l = 84 cm corresponding to single-path propagation, the ASE spectral width for the homogeneously broadened transition was calculated to be 6.28 Å, to be compared with the measured 4.1 Å spectral width reported for a KrF oscillator utilizing a two-mirror resonator. With the gain parameters obtained from the ASE energy measurements, the unsaturated and saturated gain coefficients for l = 84 cm were calculated to be 0.042 cm −1 and 0.014 cm −1 , respectively. These values of the gain coefficient are comparable to but slightly lower than the measured gain coefficient for laser systems of 80–100 cm excitation lengths reported from different laboratories. (letter)

Finite-time stabilization for a class of nonholonomic feedforward systems subject to inputs saturation.

Science.gov (United States)

Gao, Fangzheng; Yuan, Ye; Wu, Yuqiang

2016-09-01

This paper studies the problem of finite-time stabilization by state feedback for a class of uncertain nonholonomic systems in feedforward-like form subject to inputs saturation. Under the weaker homogeneous condition on systems growth, a saturated finite-time control scheme is developed by exploiting the adding a power integrator method, the homogeneous domination approach and the nested saturation technique. Together with a novel switching control strategy, the designed saturated controller guarantees that the states of closed-loop system are regulated to zero in a finite time without violation of the constraint. As an application of the proposed theoretical results, the problem of saturated finite-time control for vertical wheel on rotating table is solved. Simulation results are given to demonstrate the effectiveness of the proposed method. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Cyanobacterial diversity and related sedimentary facies as a function of water flow conditions: Example from the Monasterio de Piedra Natural Park (Spain)

Science.gov (United States)

Berrendero, Esther; Arenas, Concha; Mateo, Pilar; Jones, Brian

2016-05-01

The River Piedra in the Monasterio de Piedra Natural Park (NE Spain) is a modern tufa-depositing river that encompasses various depositional environments that are inhabited by different cyanobacterial populations. Molecular (16S rDNA) and morphological analyses of the cyanobacteria from different facies showed that Phormidium incrustatum dominates in the fast-flowing water areas where the mean depositional rate is 1.6 cm/year. Stromatolites in these areas are formed of palisades of hollow calcite tubes (inner diameter of 6.0-7.5 μm, walls 2-12 μm thick) that formed through calcite encrustation around the filaments followed by decay of the trichomes. In contrast, in slow-flowing water areas with lower depositional rates (mean depositional rate of 0.3 cm/year), Phormidium aerugineo-caeruleum is the dominant species. In these areas, randomly oriented calcite tubes (inner diameter of 5-6 μm, walls 3-8 μm thick) formed by calcite encrustation, are found in thin and uneven laminae and as scattered tubes in the loose lime mud and sand-sized carbonate sediment. Although this species did not build laminated deposits, it gave cohesiveness to the loose sediment. In the stepped and low waterfalls, with intermediate deposition rates (mean depositional rate of 0.9 cm/year), both species of Phormidium are found in association with spongy moss and algal boundstones, which is consistent with the variable flow conditions in this setting. The calcite encrustations on the cyanobacteria from different environments exhibit irregular patterns that may be linked to changes in the calcite saturation index. The physicochemical conditions associated with extracellular polymeric substances may be more significant to CaCO3 precipitation in microbial mats in slow-flowing water conditions than in fast-flowing water conditions. These results show that flow conditions may influence the distribution of different cyanobacteria that, in turn, leads to the development of different sedimentary

Three-dimensional geophysical mapping of shallow water saturated altered rocks at Mount Baker, Washington: Implications for slope stability

Science.gov (United States)

Finn, Carol A.; Deszcz-Pan, Maryla; Ball, Jessica L.; Bloss, Benjamin J.; Minsley, Burke J.

2018-05-01

Water-saturated hydrothermal alteration reduces the strength of volcanic edifices, increasing the potential for catastrophic sector collapses that can lead to far traveled and destructive debris flows. Intense hydrothermal alteration significantly lowers the resistivity and magnetization of volcanic rock and therefore hydrothermally altered rocks can be identified with helicopter electromagnetic and magnetic measurements. Geophysical models constrained by rock properties and geologic mapping show that intensely altered rock is restricted to two small (500 m diameter), >150 m thick regions around Sherman Crater and Dorr Fumarole Field at Mount Baker, Washington. This distribution of alteration contrasts with much thicker and widespread alteration encompassing the summits of Mounts Adams and Rainier prior to the 5600 year old Osceola collapse, which is most likely due to extreme erosion and the limited duration of summit magmatism at Mount Baker. In addition, the models suggest that the upper 300 m of rock contains water which could help to lubricate potential debris flows. Slope stability modeling incorporating the geophysically modeled distribution of alteration and water indicates that the most likely and largest ( 0.1 km3) collapses are from the east side of Sherman Crater. Alteration at Dorr Fumarole Field raises the collapse hazard there, but not significantly because of its lower slope angles. Geochemistry and analogs from other volcanoes suggest a model for the edifice hydrothermal system.

Three-dimensional geophysical mapping of shallow water saturated altered rocks at Mount Baker, Washington: Implications for slope stability

Science.gov (United States)

Finn, Carol A.; Deszcz-Pan, Maria; Ball, Jessica L.; Bloss, Benjamin J.; Minsley, Burke J.

2018-01-01

Water-saturated hydrothermal alteration reduces the strength of volcanic edifices, increasing the potential for catastrophic sector collapses that can lead to far traveled and destructive debris flows. Intense hydrothermal alteration significantly lowers the resistivity and magnetization of volcanic rock and therefore hydrothermally altered rocks can be identified with helicopter electromagnetic and magnetic measurements. Geophysical models constrained by rock properties and geologic mapping show that intensely altered rock is restricted to two small (500 m diameter), >150 m thick regions around Sherman Crater and Dorr Fumarole Field at Mount Baker, Washington. This distribution of alteration contrasts with much thicker and widespread alteration encompassing the summits of Mounts Adams and Rainier prior to the 5600 year old Osceola collapse, which is most likely due to extreme erosion and the limited duration of summit magmatism at Mount Baker. In addition, the models suggest that the upper ~300 m of rock contains water which could help to lubricate potential debris flows. Slope stability modeling incorporating the geophysically modeled distribution of alteration and water indicates that the most likely and largest (~0.1 km3) collapses are from the east side of Sherman Crater. Alteration at Dorr Fumarole Field raises the collapse hazard there, but not significantly because of its lower slope angles. Geochemistry and analogs from other volcanoes suggest a model for the edifice hydrothermal system.

Adsorption of Dissolved Gases (CH4, CO2, H2, Noble Gases) by Water-Saturated Smectite Clay Minerals

Science.gov (United States)

Bourg, I. C.; Gadikota, G.; Dazas, B.

2016-12-01

Adsorption of dissolved gases by water-saturated clay minerals plays important roles in a range of fields. For example, gas adsorption in on clay minerals may significantly impact the formation of CH4 hydrates in fine-grained sediments, the behavior of CH4 in shale, CO2 leakage across caprocks of geologic CO2 sequestration sites, H2 leakage across engineered clay barriers of high-level radioactive waste repositories, and noble gas geochemistry reconstructions of hydrocarbon migration in the subsurface. Despite its importance, the adsorption of gases on clay minerals remains poorly understood. For example, some studies have suggested that clay surfaces promote the formation of CH4 hydrates, whereas others indicate that clay surfaces inhibit the formation of CH4 hydrates. Here, we present molecular dynamics (MD) simulations of the adsorption of a range of gases (CH4, CO2, H2, noble gases) on clay mineral surfaces. Our results indicate that the affinity of dissolved gases for clay mineral surfaces has a non-monotone dependence on the hydrated radius of the gas molecules. This non-monotone dependence arises from a combination of two effects: the polar nature of certain gas molecules (in particular, CO2) and the templating of interfacial water structure by the clay basal surface, which results in the presence of interfacial water "cages" of optimal size for intermediate-size gas molecules (such as Ne or Ar).

In-situ gas hydrate hydrate saturation estimated from various well logs at the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

Science.gov (United States)

Lee, M.W.; Collett, T.S.

2011-01-01

In 2006, the U.S. Geological Survey (USGS) completed detailed analysis and interpretation of available 2-D and 3-D seismic data and proposed a viable method for identifying sub-permafrost gas hydrate prospects within the gas hydrate stability zone in the Milne Point area of northern Alaska. To validate the predictions of the USGS and to acquire critical reservoir data needed to develop a long-term production testing program, a well was drilled at the Mount Elbert prospect in February, 2007. Numerous well log data and cores were acquired to estimate in-situ gas hydrate saturations and reservoir properties.Gas hydrate saturations were estimated from various well logs such as nuclear magnetic resonance (NMR), P- and S-wave velocity, and electrical resistivity logs along with pore-water salinity. Gas hydrate saturations from the NMR log agree well with those estimated from P- and S-wave velocity data. Because of the low salinity of the connate water and the low formation temperature, the resistivity of connate water is comparable to that of shale. Therefore, the effect of clay should be accounted for to accurately estimate gas hydrate saturations from the resistivity data. Two highly gas hydrate-saturated intervals are identified - an upper ???43 ft zone with an average gas hydrate saturation of 54% and a lower ???53 ft zone with an average gas hydrate saturation of 50%; both zones reach a maximum of about 75% saturation. ?? 2009.

Experimental study of the permeability of concrete under variable thermal and hydric conditions

International Nuclear Information System (INIS)

Chen, W.

2011-01-01

The main objective of this study is to evaluate the variable thermal and hydric effect, with fissuration effect on the hydraulic behaviour of two concretes. Many experimental tests (saturation and permeability measurements, uniaxial and triaxial compressions tests) were carried out in order to investigate the temperature and saturation influence on the behaviour hydraulic on sound and micro-cracked concrete. Moreover, an experimental device for permeability measurement on macro-cracked concrete was realized, it allows to study the behaviour of macro-cracked of concrete confined and subjected to dry gas flow or very moist air at different temperatures. Multiaxial mechanical tests are coupled to the permeability measurements of sound concrete and micro-cracked by freezing and thawing, which allow to measuring the permeability under deviatoric load-unload with the effect of pre-cracking under stress. We also effectuated a test of relative permeability of concrete as a function of water saturation, subjected to drying and re-saturation, conditioning by the different relative humidity imposed. (author)

Photoacoustic infrared spectroscopy for conducting gas tracer tests and measuring water saturations in landfills

International Nuclear Information System (INIS)

Jung, Yoojin; Han, Byunghyun; Mostafid, M. Erfan; Chiu, Pei; Yazdani, Ramin; Imhoff, Paul T.

2012-01-01

Highlights: ► Photoacoustic infrared spectroscopy tested for measuring tracer gas in landfills. ► Measurement errors for tracer gases were 1–3% in landfill gas. ► Background signals from landfill gas result in elevated limits of detection. ► Technique is much less expensive and easier to use than GC. - Abstract: Gas tracer tests can be used to determine gas flow patterns within landfills, quantify volatile contaminant residence time, and measure water within refuse. While gas chromatography (GC) has been traditionally used to analyze gas tracers in refuse, photoacoustic spectroscopy (PAS) might allow real-time measurements with reduced personnel costs and greater mobility and ease of use. Laboratory and field experiments were conducted to evaluate the efficacy of PAS for conducting gas tracer tests in landfills. Two tracer gases, difluoromethane (DFM) and sulfur hexafluoride (SF 6 ), were measured with a commercial PAS instrument. Relative measurement errors were invariant with tracer concentration but influenced by background gas: errors were 1–3% in landfill gas but 4–5% in air. Two partitioning gas tracer tests were conducted in an aerobic landfill, and limits of detection (LODs) were 3–4 times larger for DFM with PAS versus GC due to temporal changes in background signals. While higher LODs can be compensated by injecting larger tracer mass, changes in background signals increased the uncertainty in measured water saturations by up to 25% over comparable GC methods. PAS has distinct advantages over GC with respect to personnel costs and ease of use, although for field applications GC analyses of select samples are recommended to quantify instrument interferences.

Direct laboratory observation of fluid distribution and its influence on acoustic properties of patchy saturated rocks

Science.gov (United States)

Lebedev, M.; Clennell, B.; Pervukhina, M.; Shulakova, V.; Mueller, T.; Gurevich, B.

2009-04-01

Porous rocks in hydrocarbon reservoirs are often saturated with a mixture of two or more fluids. Interpretation of exploration seismograms requires understanding of the relationship between distribution of the fluids patches and acoustic properties of rocks. The sizes of patches as well as their distribution affect significantly the seismic response. If the size of the fluid patch is smaller than the diffusion wavelength then pressure equilibration is achieved and the bulk modulus of the rock saturated with a mixture is defined by the Gassmann equations (Gassmann, 1951) with the saturation-weighted average of the fluid bulk modulus given by Wood's law (Wood, 1955, Mavko et al., 1998). If the fluid patch size is much larger than the diffusion wavelength then there is no pressure communication between different patches. In this case, fluid-flow effects can be neglected and the overall rock may be considered equivalent to an elastic composite material consisting of homogeneous parts whose properties are given by Gassmann theory with Hill's equation for the bulk modulus (Hill, 1963, Mavko et al., 1998). At intermediate values of fluid saturation the velocity-saturation relationship is significantly affected by the fluid patch distribution. In order to get an improved understanding of factors influencing the patch distribution and the resulting seismic wave response we performed simultaneous measurements of P-wave velocities and rock sample CT imaging. The CT imaging allows us to map the fluid distribution inside rock sample during saturation (water imbibition). We compare the experimental results with theoretical predictions. In this paper we will present results of simultaneous measurements of longitudinal wave velocities and imaging mapping of fluid distribution inside rock sample during sample saturation. We will report results of two kinds of experiments: "dynamic" and "quasi static" saturation. In both experiments Casino Cores Otway Basin sandstone, Australia core

Osmosis-induced water uptake by Eurobitum bituminized radioactive waste and pressure development in constant volume conditions

International Nuclear Information System (INIS)

Mariën, A.; Mokni, N.; Valcke, E.; Olivella, S.; Smets, S.; Li, X.

2013-01-01

Highlights: ► The water uptake by Eurobitum is studied to judge the safety of geological disposal. ► High pressures of up to 20 MPa are measured in constant volume water uptake tests. ► The morphology of leached Eurobitum samples is studied with μCT and ESEM. ► The observations are reproduced by an existing CHM formulation for Eurobitum. - Abstract: The chemo-hydro-mechanical (CHM) interaction between swelling Eurobitum radioactive bituminized waste (BW) and Boom Clay is investigated to assess the feasibility of geological disposal for the long-term management of this waste. These so-called compatibility studies include laboratory water uptake tests at Belgian Nuclear Research Center SCK-CEN, and the development of a coupled CHM formulation for Eurobitum by the International Center for Numerical Methods and Engineering (CIMNE, Polytechnical University of Cataluña, Spain). In the water uptake tests, the osmosis-induced swelling, pressure increase and NaNO 3 leaching of small cylindrical BW samples (diameter 38 mm, height 10 mm) is studied under constant total stress conditions and nearly constant volume conditions; the actual geological disposal conditions should be intermediate between these extremes. Two nearly constant volume tests were stopped after 1036 and 1555 days to characterize the morphology of the hydrated BW samples and to visualize the hydrated part with microfocus X-ray Computer Tomography (μCT) and Environmental Scanning Electron Microscopy (ESEM). In parallel, a coupled CHM formulation is developed that describes chemically and hydraulically coupled flow processes in porous materials with salt crystals, and that incorporates a porosity dependent membrane efficiency, permeability and diffusivity. When Eurobitum BW is hydrated in (nearly) constant volume conditions, the osmosis-induced water uptake results in an increasing pressure to values that can be (in theory) as high as 42.8 MPa, being the osmotic pressure of a saturated NaNO 3

The impact of water table drawdown and drying on subterranean aquatic fauna in in-vitro experiments.

Directory of Open Access Journals (Sweden)

Christine Stumpp

Full Text Available The abstraction of groundwater is a global phenomenon that directly threatens groundwater ecosystems. Despite the global significance of this issue, the impact of groundwater abstraction and the lowering of groundwater tables on biota is poorly known. The aim of this study is to determine the impacts of groundwater drawdown in unconfined aquifers on the distribution of fauna close to the water table, and the tolerance of groundwater fauna to sediment drying once water levels have declined. A series of column experiments were conducted to investigate the depth distribution of different stygofauna (Syncarida and Copepoda under saturated conditions and after fast and slow water table declines. Further, the survival of stygofauna under conditions of reduced sediment water content was tested. The distribution and response of stygofauna to water drawdown was taxon specific, but with the common response of some fauna being stranded by water level decline. So too, the survival of stygofauna under different levels of sediment saturation was variable. Syncarida were better able to tolerate drying conditions than the Copepoda, but mortality of all groups increased with decreasing sediment water content. The results of this work provide new understanding of the response of fauna to water table drawdown. Such improved understanding is necessary for sustainable use of groundwater, and allows for targeted strategies to better manage groundwater abstraction and maintain groundwater biodiversity.

SATURATED ZONE IN-SITU TESTING

Energy Technology Data Exchange (ETDEWEB)

P.W. REIMUS

2004-11-08

The purpose of this scientific analysis is to document the results and interpretations of field experiments that test and validate conceptual flow and radionuclide transport models in the saturated zone (SZ) near Yucca Mountain, Nevada. The test interpretations provide estimates of flow and transport parameters used in the development of parameter distributions for total system performance assessment (TSPA) calculations. These parameter distributions are documented in ''Site-Scale Saturated Zone Flow Model (BSC 2004 [DIRS 170037]), Site-Scale Saturated Zone Transport'' (BSC 2004 [DIRS 170036]), Saturated Zone Colloid Transport (BSC 2004 [DIRS 170006]), and ''Saturated Zone Flow and Transport Model Abstraction'' (BSC 2004 [DIRS 170042]). Specifically, this scientific analysis contributes the following to the assessment of the capability of the SZ to serve as part of a natural barrier for waste isolation for the Yucca Mountain repository system: (1) The bases for selection of conceptual flow and transport models in the saturated volcanics and the saturated alluvium located near Yucca Mountain. (2) Results and interpretations of hydraulic and tracer tests conducted in saturated fractured volcanics at the C-wells complex near Yucca Mountain. The test interpretations include estimates of hydraulic conductivities, anisotropy in hydraulic conductivity, storativities, total porosities, effective porosities, longitudinal dispersivities, matrix diffusion mass transfer coefficients, matrix diffusion coefficients, fracture apertures, and colloid transport parameters. (3) Results and interpretations of hydraulic and tracer tests conducted in saturated alluvium at the Alluvial Testing Complex (ATC) located at the southwestern corner of the Nevada Test Site (NTS). The test interpretations include estimates of hydraulic conductivities, storativities, total porosities, effective porosities, longitudinal dispersivities, matrix diffusion mass

SATURATED ZONE IN-SITU TESTING

International Nuclear Information System (INIS)

REIMUS, P.W.

2004-01-01

The purpose of this scientific analysis is to document the results and interpretations of field experiments that test and validate conceptual flow and radionuclide transport models in the saturated zone (SZ) near Yucca Mountain, Nevada. The test interpretations provide estimates of flow and transport parameters used in the development of parameter distributions for total system performance assessment (TSPA) calculations. These parameter distributions are documented in ''Site-Scale Saturated Zone Flow Model (BSC 2004 [DIRS 170037]), Site-Scale Saturated Zone Transport'' (BSC 2004 [DIRS 170036]), Saturated Zone Colloid Transport (BSC 2004 [DIRS 170006]), and ''Saturated Zone Flow and Transport Model Abstraction'' (BSC 2004 [DIRS 170042]). Specifically, this scientific analysis contributes the following to the assessment of the capability of the SZ to serve as part of a natural barrier for waste isolation for the Yucca Mountain repository system: (1) The bases for selection of conceptual flow and transport models in the saturated volcanics and the saturated alluvium located near Yucca Mountain. (2) Results and interpretations of hydraulic and tracer tests conducted in saturated fractured volcanics at the C-wells complex near Yucca Mountain. The test interpretations include estimates of hydraulic conductivities, anisotropy in hydraulic conductivity, storativities, total porosities, effective porosities, longitudinal dispersivities, matrix diffusion mass transfer coefficients, matrix diffusion coefficients, fracture apertures, and colloid transport parameters. (3) Results and interpretations of hydraulic and tracer tests conducted in saturated alluvium at the Alluvial Testing Complex (ATC) located at the southwestern corner of the Nevada Test Site (NTS). The test interpretations include estimates of hydraulic conductivities, storativities, total porosities, effective porosities, longitudinal dispersivities, matrix diffusion mass transfer coefficients, and colloid

Automatic NAA. Saturation activities

International Nuclear Information System (INIS)

Westphal, G.P.; Grass, F.; Kuhnert, M.

2008-01-01

A system for Automatic NAA is based on a list of specific saturation activities determined for one irradiation position at a given neutron flux and a single detector geometry. Originally compiled from measurements of standard reference materials, the list may be extended also by the calculation of saturation activities from k 0 and Q 0 factors, and f and α values of the irradiation position. A systematic improvement of the SRM approach is currently being performed by pseudo-cyclic activation analysis, to reduce counting errors. From these measurements, the list of saturation activities is recalculated in an automatic procedure. (author)

Stabilization of Networked Control Systems with Variable Delays and Saturating Inputs

Directory of Open Access Journals (Sweden)

M. Mahmodi Kaleybar

2014-06-01

Full Text Available In this paper, improved conditions for the synthesis of static state-feedback controller are derived to stabilize networked control systems (NCSs subject to actuator saturation. Both of the data packet latency and dropout which deteriorate the performance of the closed-loop system are considered in the NCS model via variable delays. Two different techniques are employed to incorporate actuator saturation in the system description. Utilizing Lyapunov-Krasovskii Theorem, delay-dependent conditions are obtained in terms of linear matrix inequalities (LMIs to determine the static feedback gain. Moreover, an optimization problem is formulated in order to find the less conservative estimate for the region of attraction corresponding to different maximum allowable delays. Numerical examples are introduced to demonstrate the effectiveness and advantages of the proposed schemes.

Cooling water conditioning and quality control for tokamaks

International Nuclear Information System (INIS)

Gootgeld, A.M.

1995-10-01

Designers and operators of Tokamaks and all associated water cooled, peripheral equipment, are faced with the task of providing and maintaining closed-loop, low conductivity, low impurity, cooling water systems. Most of these systems must provide large volumes of high quality cooling water at reasonable cost and comply with local and state government orders and EPA mandated national pretreatment standards and regulations. This paper discusses the DIII-D water quality requirements, the means used to obtain the necessary quality and the instrumentation used for control and monitoring. Costs to mechanically and chemically condition and maintain water quality are discussed as well as the various aspects of complying with government standards and regulations

A Design Method of Robust Servo Internal Model Control with Control Input Saturation

OpenAIRE

山田, 功; 舩見, 洋祐

2001-01-01

In the present paper, we examine a design method of robust servo Internal Model Control with control input saturation. First of all, we clarify the condition that Internal Model Control has robust servo characteristics for the system with control input saturation. From this consideration, we propose new design method of Internal Model Control with robust servo characteristics. A numerical example to illustrate the effectiveness of the proposed method is shown.

Water Retention Curves of Opalinus Clay

International Nuclear Information System (INIS)

Villar, M. V.; Romero, F. J.

2012-01-01

The water retention curve of Opalinus clay samples was determined under different conditions: total and matric suction, stress or no-stress conditions, wetting and drying paths. Through the fitting of these results to the van Genuchten expression the P parameter, related to the air entry value (AEV), was obtained. The AEV is the suction value above which air is able to enter the pores of the sample, and consequently, above which 2-phase flow can take place in the soil pore structure. The samples used in this research came from two different boreholes, BHT-1 and BHG-D1, but the behaviour of them did not depend on their location, what was probably due to the fact that both were drilled in the shay facies of the Opalinus clay. There was not a distinct difference between the results obtained under total or matric suctions. In the drying paths, both the water contents and the degrees of saturation tended to be higher when total suction was applied, however the reverse trend was observed for the water contents reached in wetting paths. As well, no clear difference was observed in the water retention curves obtained in odometers under matric and total suctions, what points to the osmotic component of suction in Opalinus clay not being significant. Overall, the water contents were lower and the degrees of saturation higher when suction was applied under vertical stress, what would indicate that the water retention capacity was lower under 8 MPa vertical stress than under free volume conditions. This vertical stress value is slightly higher than the maximum in situ stress. Also, the samples showed hysteresis according to the expected behaviour, i.e. the water contents for a given suction were higher during a drying path than during a wetting path. The P values obtained were between 6 and 34 MPa, and tended to be higher for the samples tested under stress, in drying paths and when total suction was used. The air entry value calculated from the mercury intrusion porosimetry

Water Retention Curves of Opalinus Clay

Energy Technology Data Exchange (ETDEWEB)

Villar, M. V.; Romero, F. J.

2012-11-01

The water retention curve of Opalinus clay samples was determined under different conditions: total and matric suction, stress or no-stress conditions, wetting and drying paths. Through the fitting of these results to the van Genuchten expression the P parameter, related to the air entry value (AEV), was obtained. The AEV is the suction value above which air is able to enter the pores of the sample, and consequently, above which 2-phase flow can take place in the soil pore structure. The samples used in this research came from two different boreholes, BHT-1 and BHG-D1, but the behaviour of them did not depend on their location, what was probably due to the fact that both were drilled in the shay facies of the Opalinus clay. There was not a distinct difference between the results obtained under total or matric suctions. In the drying paths, both the water contents and the degrees of saturation tended to be higher when total suction was applied, however the reverse trend was observed for the water contents reached in wetting paths. As well, no clear difference was observed in the water retention curves obtained in odometers under matric and total suctions, what points to the osmotic component of suction in Opalinus clay not being significant. Overall, the water contents were lower and the degrees of saturation higher when suction was applied under vertical stress, what would indicate that the water retention capacity was lower under 8 MPa vertical stress than under free volume conditions. This vertical stress value is slightly higher than the maximum in situ stress. Also, the samples showed hysteresis according to the expected behaviour, i.e. the water contents for a given suction were higher during a drying path than during a wetting path. The P values obtained were between 6 and 34 MPa, and tended to be higher for the samples tested under stress, in drying paths and when total suction was used. The air entry value calculated from the mercury intrusion porosimetry

Direct Numerical Simulations of Dynamic Drainage and Imbibition to Investigate Capillary Pressure-Saturation-Interfacial Area Relation

Science.gov (United States)