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Auswahl der wissenschaftlichen Literatur zum Thema „Water concentration profile“
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Zeitschriftenartikel zum Thema "Water concentration profile"
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Zolfaghari, Ashkan, Hassan Dehghanpour, Ebrahim Ghanbari und Doug Bearinger. „Fracture Characterization Using Flowback Salt-Concentration Transient“. SPE Journal 21, Nr. 01 (18.02.2016): 233–44. http://dx.doi.org/10.2118/168598-pa.
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Summary As observed in many shale-gas operations, salt concentration of flowback water increases with time. Usually, the shape of salt-concentration/load-recovery plots is different from one well to another. We hypothesize that the shape of the salinity profile during the flowback process provides useful information about the complexity of the fracture network. In this study, we propose a model to describe the relationship between salinity and cumulative water production. We also compare the model results and flowback-salinity data to characterize the fracture network. Flowback-salinity data are collected from three multifractured horizontal wells completed in the three shale members [Muskwa (Mu), Otter-Park (OP), and Evie (Ev)] of the Horn River Basin. The salinity profiles for the Mu and OP wells initially increase and finally reach a plateau, whereas the salinity profile for the Ev well shows a continuous increase and does not show a plateau. We hypothesize that the early water with lower salt concentration at the onset of the flowback process is mainly produced from the primary fractures with larger aperture size. Also, we believe that the fractures with smaller aperture size become more important as the flowback process progresses, and therefore, the high-salinity water produced at later times is mainly produced from secondary fractures. We also propose a model to describe the salinity-profile behaviors. The model presents the aperture-size distribution (ASD) of the fracture network. A comparative analysis of the model results and the flowback-salinity data indicates that the Ev well with a steady increase in its salinity profile has a wider ASD compared with the Mu and OP wells with a plateau in their salinity profiles. This suggests that the fracture network is more complex in Ev compared with those in Mu and OP. More-complex fracture network in Ev is also in agreement with its higher gas and lower water recovery during the flowback process as opposed to the lower gas and higher water recovery in Mu and OP. The presented model for describing the behavior of the salinity profile during the flowback process and its meaningful relationship to the fracture-network complexity provide an alternative approach for reservoir characterization. This study encourages the industry to manage the flowback operations carefully and to monitor the water chemistry.
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Carvalho, Ramon Santos, Valéria Melo Mendonça, Gilton José Ferreira da Silva und Mário Jorge Campos dos Santos. „Patentometric Profile of Social Water“. International Journal for Innovation Education and Research 8, Nr. 6 (01.06.2020): 255–65. http://dx.doi.org/10.31686/ijier.vol8.iss6.2410.
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There are regions of the planet that are affected by climatological conditions that cause water scarcity. Thus, innovative techniques have emerged with the purpose of mitigating the reflexes caused by the natural factor: drought. These innovations arise with the objective of capturing, storing and carrying out rainwater treatment for the population. These, called social water technologies, comprise products, techniques or replicable methodologies that are developed specifically to solve the problem of water shortages. The present work aims to analyze the profile of innovations generated by social water technologies through the LATIPAT, INPI and WIPO bases. To search for patents, keywords that were relevant to the research were used and combined with Boolean operators. 907 patents were identified, the largest concentration of deposits in China, justified by the fact that the country adopts development policies that invest in R&D, differentiating itself from other countries. Among the patents analyzed there is a higher concentration of deposits related to the area of human needs and water treatment.
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Kim, Dong-Lae, und Minoru Tomozawa. „Water concentration profile in silica glasses during surface crystallization“. Journal of Non-Crystalline Solids 279, Nr. 2-3 (Februar 2001): 179–85. http://dx.doi.org/10.1016/s0022-3093(00)00400-2.
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Begum, Abida, M. Ramaiah, Harikrishna, Irfanulla Khan und K. Veena. „Heavy Metal Pollution and Chemical Profile of Cauvery River Water“. E-Journal of Chemistry 6, Nr. 1 (2009): 47–52. http://dx.doi.org/10.1155/2009/154610.
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Analysis of water, plankton, fish and sediment reveals that the Cauvery River water in the downstream is contaminated by certain heavy metals. Water samples have high carbonate hardness. Concentrations of all elements and ions increase in the downstream. Main ions are in the following order: Na > HCO3>Mg > K > Ca> Cl > SO4. Heavy metal concentration in water was Cr >Cu ≈ Mn > Co > Ni > Pb > Zn, in fish muscles Cr > Mn > Cu > Ni > Co > Pb ≈ Zn, in phytoplanktens Co > Zn > Pb > Mn > Cr and in the sediments the heavy metal concentration was Co > Cr > Ni ≈ Cu > Mn > Zn > Pb. Although, the quality of Cauvery River may be classified as very good based on the salt and sodium for irrigation, Zn, Pb and Cr concentration exceeded the upper limit of standards. Metal concentrations in the downstream indicate an increase in the pollution load due to movement of fertilizers, agricultural ashes, industrial effluents and anthropogenic wastes. An immediate attention from the concerned authorities is required in order to protect the river from further pollution.
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Cheng, Chen, Zhi Yao Song, Yi Gang Wang und Jin Shan Zhang. „On the Suspended Sediment Concentration Profile“. Applied Mechanics and Materials 212-213 (Oktober 2012): 20–24. http://dx.doi.org/10.4028/www.scientific.net/amm.212-213.20.
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After analyzing the surface-boundary condition of suspended sediment concentration (SSC), Cheng et al.[7] further improved the sediment diffusion coefficient which was proposed by Bose and Dey[6]. Then an improved Rouse law (IRL) was developed. This equation, which has a similar form as Rouse law, not only overcomes the zero concentration at the free surface, but also behaves generally better than Rouse law and van Rijn equation over the whole water depth in the verification analysis. In this paper, the surface-boundary condition of SSC is further analyzed. It is elucidated that IRL satisfies the surface-boundary condition more reasonably than Rouse law. In addition, a first-order approximation of IRL is developed. From this approximation, we can easily get the explicit expression of the depth-averaged SSC without any implicit integrals to be solved numerically or by the help of a chart. This is very useful in the further study of non-equilibrium suspended sediment transport (SST).
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Srinivasan, PT, und T. Viraraghavan. „Characterisation and concentration profile of aluminium during drinking-water treatment“. Water SA 28, Nr. 1 (01.01.2002): 99. http://dx.doi.org/10.4314/wsa.v28i1.4873.
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Barabash, V., A. Osepian und P. Dalin. „Influence of water vapour on the height distribution of positive ions, effective recombination coefficient and ionisation balance in the quiet lower ionosphere“. Annales Geophysicae 32, Nr. 3 (11.03.2014): 207–22. http://dx.doi.org/10.5194/angeo-32-207-2014.
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Abstract. Mesospheric water vapour concentration effects on the ion composition and electron density in the lower ionosphere under quiet geophysical conditions were examined. Water vapour is an important compound in the mesosphere and the lower thermosphere that affects ion composition due to hydrogen radical production and consequently modifies the electron number density. Recent lower-ionosphere investigations have primarily concentrated on the geomagnetic disturbance periods. Meanwhile, studies on the electron density under quiet conditions are quite rare. The goal of this study is to contribute to a better understanding of the ionospheric parameter responses to water vapour variability in the quiet lower ionosphere. By applying a numerical D region ion chemistry model, we evaluated efficiencies for the channels forming hydrated cluster ions from the NO+ and O2+ primary ions (i.e. NO+.H2O and O2+.H2O, respectively), and the channel forming H+(H2O)n proton hydrates from water clusters at different altitudes using profiles with low and high water vapour concentrations. Profiles for positive ions, effective recombination coefficients and electrons were modelled for three particular cases using electron density measurements obtained during rocket campaigns. It was found that the water vapour concentration variations in the mesosphere affect the position of both the Cl2+ proton hydrate layer upper border, comprising the NO+(H2O)n and O2+(H2O)n hydrated cluster ions, and the Cl1+ hydrate cluster layer lower border, comprising the H+(H2O)n pure proton hydrates, as well as the numerical cluster densities. The water variations caused large changes in the effective recombination coefficient and electron density between altitudes of 75 and 87 km. However, the effective recombination coefficient, αeff, and electron number density did not respond even to large water vapour concentration variations occurring at other altitudes in the mesosphere. We determined the water vapour concentration upper limit at altitudes between 75 and 87 km, beyond which the water vapour concentration ceases to influence the numerical densities of Cl2+ and Cl1+, the effective recombination coefficient and the electron number density in the summer ionosphere. This water vapour concentration limit corresponds to values found in the H2O-1 profile that was observed in the summer mesosphere by the Upper Atmosphere Research Satellite (UARS). The electron density modelled using the H2O-1 profile agreed well with the electron density measured in the summer ionosphere when the measured profiles did not have sharp gradients. For sharp gradients in electron and positive ion number densities, a water profile that can reproduce the characteristic behaviour of the ionospheric parameters should have an inhomogeneous height distribution of water vapour.
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Zima, P., J. Makinia, M. Swinarski und K. Czerwionka. „Effects of different hydraulic models on predicting longitudinal profiles of reactive pollutants in activated sludge reactors“. Water Science and Technology 58, Nr. 3 (01.08.2008): 555–61. http://dx.doi.org/10.2166/wst.2008.676.
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This paper presents effects of dispersion on predicting longitudinal ammonia concentration profiles in activated sludge bioreactor located at “Wschod” WWTP in Gdansk. The aim of this study was to use the one-dimensional advection-dispersion Equation (ADE) to simulate the flow conditions (based on the inert tracer concentrations in selected points) and longitudinal profile of reactive pollutant (based on the ammonia concentration profiles in selected points). The simulation results were compared with the predictions obtained using a traditional “tanks-in-series” (TIS) approach, commonly used in designing biological reactors. The use of dispersion coefficient calculated from an empirical formula resulted in substantial differences in the tracer concentration distributions in two sampling points in the bioreactor. Simulations using the one-dimensional ADE and TIS model, with the nitrification rate incorporated as the source term, revealed that the hydraulic model plays a minor role compared to the biochemical transformations in predicting the longitudinal ammonia concentration profiles.
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Smith, R. „Multi-mode models of flow and of solute dispersion in shallow water. Part 2. Logarithmic velocity profiles“. Journal of Fluid Mechanics 286 (10.03.1995): 277–90. http://dx.doi.org/10.1017/s0022112095000735.
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A two-mode model for velocity and solute concentration in shallow-water flows is derived which allows for departures from the logarithmic velocity profile and from vertically well-mixed concentrations. The modelling is tested against exact results for a buoyancy-driven transverse flow and for a modified logarithmic velocity profile.
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Arsenault, Guy, Alexandre D. Cvetkovic und Radovan Popovic. „Toxic Effects of Copper on Selenastrum capricornutum Measured by a Plow Cytometry-Based Method“. Water Quality Research Journal 28, Nr. 4 (01.11.1993): 757–66. http://dx.doi.org/10.2166/wqrj.1993.041.
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Abstract Adaptation of algae Selenastrum capricornutum to different copper concentrations (50,150,300 and 450 ppb) was investigated. A flow cytometry technique was used to evaluate esterase activity (staining probe: CFDA). Algal physiological stress was estimated by comparing the esterase activity profile of intoxicated samples to that of a control sample. Our results show that at high concentration (450 ppb), copper strongly reduces esterase activity, whereas it increases that activity at lower concentrations (<300 ppb). After 27 hours of incubation, the esterase activity level resumed to the normal profile for each copper concentrations. The esterase activity profile thus shows adaption processes of algae Selenastrum capricornutum to copper intoxication.
Dissertationen zum Thema "Water concentration profile"
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Skoglund, Emil. „A NUMERICAL MODEL OF HEAT- AND MASS TRANSFER IN POLYMER ELECTROLYTE FUEL CELLS : A two-dimensional 1+1D approach to solve the steady-state temperature- and mass- distributions“. Thesis, Mälardalens högskola, Framtidens energi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-55223.
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Methods of solving the steady state characteristics of a node matrix equation system over a polymer electrolyte fuel cell (PEFC) were evaluated. The most suitable method, referred to as the semi-implicit method, was set up in a MATLAB program. The model covers heat transfer due to thermal diffusion throughout the layers and due to thermal advection+diffusion in the gas channels. Included mass transport processes cover only transport of water vapor and consist of the same diffusion/advection schematics as the heat transfer processes. The mass transport processes are hence Fickian diffusion throughout all the layers and diffusion+advection in the gas channels. Data regarding all the relevant properties of the layer materials were gathered to simulate these heat- and mass transfer processes.Comparing the simulated temperature profiles obtained with the model to the temperature profiles of a previous work’s model, showed that the characteristics and behavior of the temperature profile are realistic. There were however differences between the results, but due to the number of unknown parameters in the previous work’s model it was not possible to draw conclusions regarding the accuracy of the model by comparing the results.Comparing the simulated water concentration profiles of the model and measured values, showed that the model produced concentration characteristics that for the most part alignedwell with the measurement data. The part of the fuel cell where the concentration profile did not match the measured data was the cathode side gas diffusion layer (GDL). This comparison was however performed with the assumption that relative humidity corresponds to liquid water concentration, and that this liquid water concentration is in the same range as the measured data. Because of this assumption it was not possible to determine the accuracy of the model.
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Nakagawa, Satoshi, Kazuyuki Chihara und Kuniyasu Ogawa. „2D Projective imaging of water concentration profiles in adsorption columns by MRI“. Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-185019.
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Nakagawa, Satoshi, Kazuyuki Chihara und Kuniyasu Ogawa. „2D Projective imaging of water concentration profiles in adsorption columns by MRI“. Diffusion fundamentals 16 (2011) 42, S. 1-2, 2011. https://ul.qucosa.de/id/qucosa%3A13777.
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Ogston, Andrea S. „Influence of breaking waves on sediment concentration profiles and longshore sediment flux in the nearshore zone /“. Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/11042.
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Wilson, Christopher Brant. „Measurement of chemical composition and pH profiles near the liquid-vapor interface of aqueous solutions using a unique confocal microscope system /“. Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/9840.
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Krah, Nils [Verfasser], und Bernd [Akademischer Betreuer] Jähne. „Visualization of air and water-sided concentration profiles in laboratory gas exchange experiments / Nils Krah ; Betreuer: Bernd Jähne“. Heidelberg : Universitätsbibliothek Heidelberg, 2014. http://d-nb.info/1180031547/34.
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Friman, Sonja Isabella [Verfasser], und Bernd [Akademischer Betreuer] Jähne. „Laboratory investigations of concentration and wind profiles close to the wind-driven wavy water surface / Sonja Isabella Friman ; Betreuer: Bernd Jähne“. Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://d-nb.info/1210490013/34.
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Friman, Sonja I. [Verfasser], und Bernd [Akademischer Betreuer] Jähne. „Laboratory investigations of concentration and wind profiles close to the wind-driven wavy water surface / Sonja Isabella Friman ; Betreuer: Bernd Jähne“. Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://nbn-resolving.de/urn:nbn:de:bsz:16-heidok-283105.
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Lawrence, Cameron Eoin. „Measurement of 222Rn Exhalation Rates and 210Pb Deposition Rates in a Tropical Environment“. Queensland University of Technology, 2006. http://eprints.qut.edu.au/16291/.
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This thesis provides the measurements of 222Rn exhalation rates, 210Pb deposition rates and excess 210Pb inventories for locations in and around Ranger Uranium Mine and Jabiru located within Kakadu National Park, Australia. Radon-222 is part of the natural 238U series decay chain and the only gas to be found in the series under normal conditions. Part of the natural redistribution of 222Rn in the environment is a portion exhales from the ground and disperses into the atmosphere. Here it decays via a series of short-lived progeny, that attach themselves to aerosol particles, to the long lived isotope 210Pb (T1/2 = 22.3 y). Attached and unattached 210Pb is removed from the atmosphere through wet and dry deposition and deposited on the surface of the earth, the fraction deposited on soils is gradually transported through the soil and can create a depth profile of 210Pb. Here it decays to the stable isotope 206Pb completing the 238U series. Measurements of 222Rn exhalation rates and 210Pb deposition rates were performed over complete seasonal cycles, August 2002 - July 2003 and May 2003 - May 2004 respectively. The area is categorised as wet and dry tropics and it experiences two distinct seasonal patterns, a dry season (May-October) with little or no precipitation events and a wet season (December-March) with almost daily precipitation and monsoonal troughs. November and April are regarded as transitional months. As the natural processes of 222Rn exhalation and 210Pb deposition are heavily influenced by soil moisture and precipitation respectively, seasonal variations in the exhalation and deposition rates were expected. It was observed that 222Rn exhalation rates decreased throughout the wet season when the increase in soil moisture retarded exhalation. Lead-210 deposition peaked throughout the wet season as precipitation is the major scavenging process of this isotope from the atmosphere. Radon-222 is influenced by other parameters such as 226Ra activity concentration and distribution, soil porosity and grain size. With the removal of the influence of soil moisture during the dry season it was possible to examine the effect of these other variables in a more comprehensive manner. This resulted in categorisation of geomorphic landscapes from which the 222Rn exhalation rate to 226Ra activity concentration ratios were similar during the dry season. These results can be extended to estimate dry season 222Rn exhalation rates from tropical locations from a measurement of 226Ra activity concentration. Through modelling the 210Pb budget on local and regional scales it was observed that there is a net loss of 210Pb from the region, the majority of which occurs during the dry season. This has been attributed to the fact that 210Pb attached to aerosols is transported great distance with the prevailing trade winds created by a Hadley Circulation cell predominant during the dry season (winter) months. By including the influence of factors such as water inundation and natural 210Pb redistribution in the soil wet season budgeting of 210Pb on local and regional scales gave very good results.
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Nordström, Albin. „Denitrification in a Low Temperature Bioreactor System : Laboratory column studies“. Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-226585.
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Denitrification is a microbially-catalyzed reaction which reduces nitrate to N2 through a series of intermediate nitrogen compounds. Nitrate is a nutrient and its release into the environment may lead to eutrophication, depending on the amount that is released and the state of the recipient. The release of nitrate from the mining industry in Kiruna (Sweden) has been identified as an eutrophication risk, and a denitrifying bioreactor is to be constructed at the site to reduce the nitrate release.Since the denitrification rate decreases with temperature and the temperature in Kiruna during large parts of the year drops below 0˚C, the denitrifying bioreactor therefore has to be designed for the site-specific environment in terms of flow rate and hydraulic residence time. Laboratory column studies are used to study and determine the nitrate removal rate in a low temperature environment (5˚C) with pine wood chips as reactive matrix/ electron donor; the input solution had an average concentration of 35 mg NO3-N/L and a high sulfate concentration. Nitrate removal was studied as a function of hydraulic residence time and temperature. Parameters that were monitored include pH, alkalinity and concentrations of ammonium, nitrite and sulfate in the effluent from the columns. On three occasions, samples were gathered along the flow path in the columns (concentration profiles) such that changes in nitrate, nitrite, and occasionally ammonium concentration could be studied in relation to each other. The study concluded that a denitrifying bioreactor utilizing pine wood chips as the reactive matrix is a suitable option for nitrate treatment in a low temperature (5˚C) environment. Under the conditions of the study, effluent nitrate, nitrite, and ammonium concentrations are below limits established in legislation. Nitrate removal rates are given for zero-order nitrate reduction and overall first-order nitrate reduction, as the concentration profiles revealed a decrease in nitrate removal rate as nitrate concentration dropped below 3 mg NO3-N/L.Nitrat är ett näringsämne som kan orsaka övergödning vid utsläpp, beroende på halterna och recipienten. Växterna som tar upp kväve kommer så småningom att dö och sjunka mot botten där de förmultnar. Förmultningen kräver syre, och vid ökad växtlighet så ökar även konsumtionen av syre då det finns mer organiskt material att bryta ned. Detta leder i slutändan till syrefria områden, där djurliv och växtlighet är mer begränsade. Nitratutsläpp från gruvindustrin i Kiruna har blivit identifierad som en potentiell övergödningsrisk och en denitrifierande bioreaktor ska därmed installeras för att minska utsläppen. Denitrifikation är en mikrobiell reaktion som reducerar nitrat till kvävgas genom en serie av intermediära kväveföreningar. En denitrifierande bioreaktor använder sig utav denitrifikation för att minska nitratkoncentrationer i vatten som passerar genom bioreaktorn som består av huvudsakligen; (1) bakterierna som sköter denitrifikationen, och (2) en kolkälla som fungerar som ”mat” till de denitrifierande bakterierna, Hastigheten varvid nitrat omvandlas till kvävgas genom denitrifikation, minskar med temperatur och den denitrifierande bioreaktorn måste därmed anpassas till omgivningen där den ska placeras med avseende på uppehållstid i reaktorn. Uppehållstiden måste vara tillräcklig för att minska nitratkoncentrationen till önskad nivå, men samtidigt så får uppehållstiden inte vara för lång då andra ämnen kan reagera och bilda ofördelaktiga produkter vid låga nitratkoncentrationer. Kolonnstudier i en låg-tempererad miljö (5˚C) är ett första steg för att studera hastigheten av nitratförbrukning i en sådan omgivning, och används i detta arbete med träflis av tall som kolkälla. Parametrar som påverkar, och varierar som ett resultat av, denitrifikation (exempelvis pH och sekundära föroreningar) övervakas. Hastigheten av nitratförbrukning som fås från kolonnstudierna kan sedan används som riktlinjer för konstruktionen av en denitrifierande bioreaktor i fältskala i Kiruna. Studiens slutsats är att en denitrifierande bioreaktor med träflis av tall som reaktivt medium är ett fungerande alternativ för nitrat reducering i en lågtempererad miljö (5˚C) då nitrat effektivt reduceras till under gränsvärden fastslagna i lag. Även andra potentiella biprodukter (exempelvis nitrit och ammonium) som kan resultera från den miljö som den denitrifierande bioreaktorn ger upphov till är under de gränsvärden som finns fastslagna i lag.
Bücher zum Thema "Water concentration profile"
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Marzolf, G. Richard. Depth profiles of temperature, specific conductance, and oxygen concentration in Lake Powell, Arizona-Utah, 1992-95. Tucson, Ariz: U.S. Dept. of the Interior, U.S. Geological Survey, 1998.
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Rene, Eldon R., Shishir Kumar Behera und Hung Suck Park. „Predicting Adsorption Behavior in Engineered Floodplain Filtration System Using Backpropagation Neural Networks“. In Machine Learning Algorithms for Problem Solving in Computational Applications, 179–94. IGI Global, 2012. http://dx.doi.org/10.4018/978-1-4666-1833-6.ch011.
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Engineered floodplain filtration (EFF) system is an eco-friendly low-cost water treatment process wherein water contaminants can be removed, by adsorption and-or degraded by microorganisms, as the infiltrating water moves from the wastewater treatment plants to the rivers. An artificial neural network (ANN) based approach was used in this study to approximate and interpret the complex input/output relationships, essentially to understand the breakthrough times in EFF. The input parameters to the ANN model were inlet concentration of a pharmaceutical, ibuprofen (ppm) and flow rate (md– 1), and the output parameters were six concentration-time pairs (C, t). These C, t pairs were the times in the breakthrough profile, when 1%, 5%, 25%, 50%, 75%, and 95% of the pollutant was present at the outlet of the system. The most dependable condition for the network was selected by a trial and error approach and by estimating the determination coefficient (R2) value (>0.99) achieved during prediction of the testing set. The proposed ANN model for EFF operation could be used as a potential alternative for knowledge-based models through proper training and testing of variables.
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St. Louis, Daphenide, Ammcise Apply, Daphnée Michel und Evens Emmanuel. „Microplastics and Environmental Health: Assessing Environmental Hazards in Haiti“. In Environmental Health [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98371.
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Microplastics (MP) refer to all plastic particles that are less than 5 mm in size. Over the past decades, several studies have highlighted the impact of microplastics (MP) on living organisms. In addition to being pollutants themselves, these synthetic polymers also act as vectors for the transport of various types of chemicals in natural ecosystems. MP has been ubiquitously detected in a wide range of shapes, polymers, sizes and concentrations in marine water, freshwater, agroecosystems, atmospheric, food and water environments. Drinking water, biota, and other remote places. According to the World Bank, over 80% of the world’s marine litter is plastic and the concentration of litter on Caribbean beaches is often high, with a high presence of single-use plastics and food containers. In its work, the World Health Organization (WHO) suggests an in-depth assessment of microplastics present in the environment and their potential consequences on human health, following the publication of an analysis of the state of research on microplastics in drinking water. It also calls for reducing plastic pollution to protect the environment and reduce human exposure. In Haiti, the bay of Port-au-Prince is the natural receptacle of all the urban effluents generated by human activities in the Metropolitan Zone. This urban wastewater carries household waste, sludge from pit latrines and sewage, industrial wastewater which largely contributes to the pollution of the bay. Furthermore, 1,673,750 tonnes per year of household waste, including 93,730 tonnes of plastic waste, are not collected. What are the environmental dangers represented by the MP contained in those wastes for living organisms in exposed tropical ecosystems? The purpose of this paper is: (i) to do a bibliographical review of the physical and chemical properties, as well as the toxicological profile of MP, (ii) to identify the environmental hazards associated with MP contained in urban waste in the metropolitan area of Port-au-Prince.
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van Geer, F., A. Visser, H. Broers, A. Marsman und B. van der Grift. „Improving the prediction of future groundwater quality by analyzing concentration-depth profiles“. In Water-Rock Interaction. Taylor & Francis, 2007. http://dx.doi.org/10.1201/noe0415451369.ch211.
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Evans, Hugh L. „Cognitive Complications of Mercury Exposure“. In Cognitive and Behavioral Abnormalities of Pediatric Diseases. Oxford University Press, 2010. http://dx.doi.org/10.1093/oso/9780195342680.003.0072.
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Mercury (Hg) is a nonessential metal that has been used in a variety of industrial procedures and pharmaceutical preparations over centuries, resulting in hot spots of environmental contamination and unwanted toxicity in people who were occupationally exposed or were treated with mercury compounds (Clarkson and Magos 2006; Evans 1998). Mercury exists in three different chemical forms, each having a different profile of toxicity. The central nervous system (CNS) is considered to be the target organ for organic mercury and elemental mercury. The kidneys are considered to be the target organ of inorganic mercury. The most widespread current exposure of children is to organic mercury from ingestion of seafood, most of which is in the form of methylmercury, the most severely neurotoxic form of mercury (Clarkson and Magos 2006). Maternal consumption of seafood, although nutritionally beneficial, has been associated with elevated mercury levels in maternal blood and hair, and with deleterious outcomes in their infants. Mothers can transit mercury to their fetus through their blood supply or to their infant through maternal milk. Children also are exposed to mercury in regions where gold is mined (Bose-O’Reilly et al. 2008). Other sources of exposures have been reviewed by Clarkson and Magos (2006). Over the past two decades in the United States, mercury has been increasingly restricted by the U.S. Environmental Protection Agency, and it has been removed from consumer products (where it had been used as a fungicide). Current efforts are under way to encourage consumers to trade their mercury thermometers for newer models that do not use mercury. Mercury has no essential nutritional role, so any amount of mercury in the body can be considered undesirable. For practical purposes, since mercury is present at some level almost everywhere on Earth, the key question is at what dose or concentration in the body can mercury-induced toxicity be documented? Continuing improvements in chemical measurement has resulted in the determining of mercury in lower concentrations. This has been matched by advances in neurological measurements and statistical analyses, resulting in the extrapolation of lower “safe” levels of mercury levels in drinking water, hair, and blood.
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Busch, Andrew M. „A Mighty Bulwark against the Blind and Raging Forces of Nature“. In City in a Garden. University of North Carolina Press, 2017. http://dx.doi.org/10.5149/northcarolina/9781469632643.003.0002.
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This chapter describes Austin’s natural features and hazards, concentrating on the Colorado River system. It then investigates how Austin’s early twentieth century business and political leaders struggled to fund dams to make the river safer and to profit from it via hydroelectricity, recreation, and water supply. Finally, it demonstrates how early environmental improvements benefited whites but not other groups.
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Kashulina, Galina, Clemens Reimann, Tor Erik Finne, Patrice de Caritat und Heikki Niskavaara. „Factors influencing NO3 concentrations in rain, stream water, ground water and podzol profiles of eight small catchments in the European Arctic“. In Nitrogen, the Confer-N-s, 559–68. Elsevier, 1998. http://dx.doi.org/10.1016/b978-0-08-043201-4.50082-4.
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Erfani Agah, Ali. „Numerical Modeling of Soil Water Flow and Nitrogen Dynamics in a Tomato Field Irrigated with Municipal Wastewater“. In Recent Advances on Numerical Simulations [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98487.
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Because of water scarcity, reduction of annual rainfall and the use of wastewater in agriculture, there is a need for research to evaluate the potential impacts of using such sources on hydraulic soil properties and groundwater quality. Nitrate loss from the area under cultivation and regular use of fertilizer and wastewater is a major reason for non-point source contamination on agricultural lands. Numerical model, Hydrus-1D used to simulate soil nitrate in soil cultivated with tomato-crop during the growing period, in North-East Iran. A randomized completely blocked design with five irrigation treatments with different sources of nitrogen was applied. Comparison between simulated and measured soil moisture content shows that the model can follow the temporal variation of soil water content. However, some over estimation of the measured data was observed during the simulation period. To evaluate the Hydrus model performance with respect to nitrogen transport and transformations, the simulated nitrogen concentrations (NH4-N and NO3-N) are compared for different treatments at different depths of soil profile, (7.5, 22.5, 37.5, 52.5 and 120 cm from soil surface). It takes about 4 days to convert 90% of urea into ammonium and it takes about 70 days to convert 90% of ammonium into nitrate. However, urea concentrations decreased with time between irrigations as a result of hydrolysis. As expected, at 3.73 days, the urea was concentrated near the surface, immediately after fertigation. Ammonium remained concentrated in the immediate in the top soil at all times for all treatments. There was only slight movement, because of soil adsorption and subsequent fast nitrification and/or root uptake. In contrast to ammonium, nitrate moved continuously downwards during the 28-day simulation period, as nitrate is not adsorbed, whereas denitrification was assumed negligible. Leaching percentages were smaller for nitrate wastewater compared to nitrate- fertilizer, and manure. Base on simulation results treated municipal wastewater by an aerated lagoon can be used as a valuable source of irrigation without causing contamination of groundwater.
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Mathews, Jennifer L., und Anne Schweighardt. „The Role of Natriuretic Peptides in the Pathophysiology and Treatment of Heart Failure“. In Emerging Applications, Perspectives, and Discoveries in Cardiovascular Research, 1–16. IGI Global, 2017. http://dx.doi.org/10.4018/978-1-5225-2092-4.ch001.
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The pathophysiology of heart failure is due in part to compensatory mechanisms utilized to maintain cardiac output. Neurohormonal responses include activation of the renin-angiotensin-aldosterone and sympathetic nervous systems leading to vasoconstriction, increased blood volume through reabsorption of sodium and water, and increased myocardial contractility and heart rate. Prolonged activation of these systems often results in a maladaptive response and a further reduction in cardiac output (Colucci, 2015). Natriuretic peptides counterbalance the neurohormonal systems by antagonizing the actions of renin-angiotensin-aldosterone, promoting vasodilation and natriuresis. In hypervolemic states atrial myocytes are stretched resulting in the release of atrial natriuretic peptide (ANP). Ventricular cells secrete brain-type natriuretic peptide (BNP) in response to the high ventricular filling pressures (de Sa, 2008). The natriuretic peptides are degraded enzymatically by neprilysin. Plasma concentrations of ANP and BNP can be used as markers for the diagnosis of heart failure (Grewal, 2004). The kidneys also produce a natriuretic peptide, urodilatin, and new studies suggest a role for this peptide in the pathophysiology and treatment of heart failure (Anker, 2015). The natriuretic peptides can be targeted therapeutically for the treatment of heart failure. Nesiritide, a recombinant preparation of human B-type natriuretic peptide (BNP), is FDA approved and has been available for several years for treatment of acute decompensations of heart failure, but has received limited use due to cost and adverse effect profile. Ularatide, a synthetic analog of urodilatin, is currently in phase three clinical trials. In addition, the FDA has recently approved an angiotensin receptor blocker-neprilysin inhibitor that has shown mortality benefit.
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Walker, James C. G. „Climate: A Chain of Identical Reservoirs“. In Numerical Adventures with Geochemical Cycles. Oxford University Press, 1991. http://dx.doi.org/10.1093/oso/9780195045208.003.0009.
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One class of important problems involves diffusion in a single spatial dimension, for example, height profiles of reactive constituents in a turbulently mixing atmosphere, profiles of concentration as a function of depth in the ocean or other body of water, diffusion and diagenesis within sediments, and calculation of temperatures as a function of depth or position in a variety of media. The one-dimensional diffusion problem typically yields a chain of interacting reservoirs that exchange the species of interest only with the immediately adjacent reservoirs. In the mathematical formulation of the problem, each differential equation is coupled only to adjacent differential equations and not to more distant ones. Substantial economies of computation can therefore be achieved, making it possible to deal with a larger number of reservoirs and corresponding differential equations. In this chapter I shall explain how to solve a one-dimensional diffusion problem efficiently, performing only the necessary calculations. The example I shall use is the calculation of the zonally averaged temperature of the surface of the Earth (that is, the temperature averaged over all longitudes as a function of latitude). I first present an energy balance climate model that calculates zonally averaged temperatures as a function of latitude in terms of the absorption of solar energy, which is a function of latitude, the emission of long-wave planetary radiation to space, which is a function of temperature, and the transport of heat from one latitude to another. This heat transport is represented as a diffusive process, dependent on the temperature gradient or the difference between temperatures in adjacent latitude bands. I use the energy balance climate model first to calculate annual average temperature as a function of latitude, comparing the calculated results with observed values and tuning the simulation by adjusting the diffusion parameter that describes the transport of energy between latitudes. I then show that most of the elements of the sleq array for this problem are zero. Nonzero elements are present only on the diagonal and immediately adjacent to the diagonal. The array has this property because each differential equation for temperature in a latitude band is coupled only to temperatures in the adjacent latitude bands.
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Clark, Gregory O., und William J. Kovacs. „Glucose, Lipid, and Protein Metabolism“. In Textbook of Endocrine Physiology. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199744121.003.0018.
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The maintenance of life requires a constant supply of substrate for the generation of energy and preservation of the structure of cells and tissues. The process in principle is simple, yet the individual metabolic pathways and the regulation of substrate fluxes through these pathways can be complex. Energy is derived when fuel substrates are oxidized to carbon dioxide and water in the presence of oxygen, generating adenosine triphosphate (ATP). A portion of the ingested foodstuff is also utilized, either directly or after transformation into other substrates, to repair and replace cell membranes, structural proteins, and organelles. The remainder is stored as potential energy in the form of glycogen or fat. Under normal circumstances, each individual remains in a near-steady state where weight and appearance are stable over prolonged periods. In the short term, fuel metabolism changes dramatically several times a day during alternating periods of feeding and fasting. An anabolic phase begins with food ingestion and lasts for several hours. Energy storage occurs during this period when caloric intake exceeds caloric demands. The catabolic phase usually begins 4 to 6 hours after a meal and lasts until the person eats once again. During this phase, utilization shifts from exogenous to endogenous fuels, a change heralded by the mobilization of substrate stored in liver, muscle, and adipose tissue. Both anabolic and catabolic phases are characterized by specific biochemical processes regulated by distinct hormonal profiles. In the anabolic phase that follows ingestion of a mixed meal, substrate flux is directed from the intestine through the liver to storage and utilization sites. Glucose, triglyceride, and amino acid concentrations increase in plasma, whereas those of fatty acids, ketones (acetoacetic and β -hydroxy-butyric acids), and glycerol decrease. Both glycogen and protein synthesis begin in liver and muscle, while fatty acid synthesis and triglyceride esterification are stimulated in hepatocytes and adipose tissue. In the catabolic phase, the biochemical activities are reversed and the flux of fuel is directed from storage depots to liver and other utilization sites.
Konferenzberichte zum Thema "Water concentration profile"
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Zhang, Ning, Weizhong Li und Jing Cui. „Molecular Dynamics Simulation of Water Transporting Through Nanotube Driven by Concentration Difference“. In ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2011. http://dx.doi.org/10.1115/icnmm2011-58023.
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A flowing water chain in a (6, 6) carbon nanotube (CNT) driven by concentration difference is studied by molecular dynamics (MD) simulation. Water molecules in the CNT form a continuous water chain, which occupy the space of a 2 Å radius along the axis of channel. By computing the trajactory from the simulation run, the water density profile along the CNT is obtained and the flow behavior of water in the CNT is studied. The simulated results show that the density distribution in the CNT is lower than that in the bulk water and the solution, but the free energy distribution appears a contrary tendency. In addition, the quantity of hydrogen-bonds (H-bonds) forming in the CNT appears a fluctuation along with time, by analyzing which, it is found that the formation of H-bonds in the CNT is related to flow rate of water.
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Wegner, Carolyn, Jens A. Ho¨lemann, Torben Klagge, Leonid Timokhov und Heidemarie Kassens. „Application of ADCPs for Long-Term Sediment Transport Monitoring in Arctic Environments: Examples From the Laptev Sea“. In 25th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/omae2006-92551.
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For offshore constructions the knowledge on sediment transport dynamics is essential and the quantification of suspended particulate matter (SPM) is of major importance. The Laptev Sea shelf is one of the largest Siberian shelf seas and ice-covered for about nine months a year. In order to use indirect measuring devices for the quantification of SPM concentration on the Laptev Sea shelf, optical (turbidity meter) and acoustic (ADCP; Acoustic Doppler Current Profiler) backscatter sensors were compared to assess their potential for the investigation of SPM dynamics in an arctic environment. To estimate SPM concentrations from optical backscatter signals, these were converted using the linear relation between the backscatter signals and SPM concentrations derived from water samples. Applying the theoretical interaction of sound in the water with SPM the acoustic backscatter signals were transformed adapting a previously established approach. SPM concentrations estimated from the backscattered signals of both sensors showed a close similarity to SPM concentrations obtained from filtered water samples. While the ADCP offers distinct advantages over the turbidity meter in that it allows measurement of the complete concentration profile, bottom location, and currents, co-deployment of both sensors are recommended for improved SPM measurements.
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Moëll, Daniel, Daniel Lörstad, Annika Lindholm, David Christensen und Xue-Song Bai. „Numerical and Experimental Investigations of the Siemens SGT-800 Burner Fitted to a Water Rig“. In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-64129.
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DLE (Dry Low Emission) technology is widely used in land based gas turbines due to the increasing demands on low NOx levels. One of the key aspects in DLE combustion is achieving a good fuel and air mixing where the desired flame temperature is achieved without too high levels of combustion instabilities. To experimentally study fuel and air mixing it is convenient to use water along with a tracer instead of air and fuel. In this study fuel and air mixing and flow field inside an industrial gas turbine burner fitted to a water rig has been studied experimentally and numerically. The Reynolds number is approximately 75000 and the amount of fuel tracer is scaled to represent real engine conditions. The fuel concentration in the rig is experimentally visualized using a fluorescing dye in the water passing through the fuel system of the burner and recorded using a laser along with a CCD (Charge Couple Device) camera. The flow and concentration field in the burner is numerically studied using both the scale resolving SAS (Scale Adaptive Simulation) method and the LES (Large Eddy Simulation) method as well as using a traditional two equation URANS (Unsteady Reynolds Average Navier Stokes) approach. The aim of this study is to explore the differences and similarities between the URANS, SAS and LES models when applied to industrial geometries as well as their capabilities to accurately predict relevant features of an industrial burner such as concentration and velocity profiles. Both steady and unsteady RANS along with a standard two equation turbulence model fail to accurately predict the concentration field within the burner, instead they predict a concentration field with too sharp gradients, regions with almost no fuel tracer as well as regions with far too high concentration of the fuel tracer. The SAS and LES approach both predict a more smooth time averaged concentration field with the main difference that the tracer profile predicted by the LES has smoother gradients as compared to the tracer profile predicted by the SAS. The concentration predictions by the SAS model is in reasonable agreement with the measured concentration fields while the agreement for the LES model is excellent. The LES shows stronger fluctuations in velocity over time as compared to both URANS and SAS which is due to the reduced amounts of eddy viscosity in the LES model as compared to both URANS and SAS. This study shows that numerical methods are capable of predicting both velocity and concentration in a gas turbine burner. It is clear that both time and scale resolved methods are required to accurately capture the flow features of this and probably most industrial DLE gas turbine burners.
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Amromin, Eduard L., und Svetlana I. Kovinskaya. „Numerical Simulation of Sediment Transport Near Shipping Channels in Harbors“. In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-33798.
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Numerical simulation of sediment transport is considered as a coupled problem based on computation of profiles of water velocity and suspended sediment concentration. Effects of the water velocity profile and turbulent pulsation on vertical motion of particles are emphasized. These effects allow explanation of amplified sediment deposit in viscous separation zones near both natural and manmade bottom irregularities (like walls of shipping channels). The unique numerical technique for separated flow computation is developed on the basis of viscous-inviscid interaction concept. This technique is validated by experimental data for turbulent flows over backward-facing steps. New results for conditions inherent to flow separation over seabed are obtained. A semi-empirical approach to determination of sediment concentration is suggested.
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Wada, Shigeo, Toshiaki Iwai und Takeshi Karino. „Optical monitoring of the concentration profile of submicron latex particles in flow through a translucent water-permeable tube: demonstration of flow-dependent concentration polarization of plasma proteins at a blood/endothelium boundary“. In Optical Engineering for Sensing and Nanotechnology (ICOSN '99), herausgegeben von Ichirou Yamaguchi. SPIE, 1999. http://dx.doi.org/10.1117/12.347796.
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Ogata, Satoshi, und Takeshi Fujita. „Effect of Surfactant Additives on a Boundary Layer on a Flat Plate“. In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-80848.
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The effect of surfactant solutions on the boundary layer over a flat plate has been investigated in the Reynolds number range of approximately Re < 153,000. Experiments were carried out by measuring the velocity profile using a PIV system. Surfactant solutions tested were aqueous solutions of oleyl-bihydroxyethyl methyl ammonium chloride (Ethoquad O/12) in the concentration range of 50 to 500 ppm, to which sodium salicylate was added as a counterion. It was clarified that the boundary layer thickness of surfactant solutions increases significantly near the leading edge comparing with that of tap water, and parallelly develops in that obtained by the Blasius equation. For lower surfactant concentration (50 and 200 ppm) the velocity profile near the wall is distributed between that of laminar flow and turbulent flow for Newtonian fluid. When the Reynolds number increases, the velocity profile gradually increases from the outer edge of the boundary, and approaches the turbulent velocity profile of Newtonian fluid. For higher surfactant concentration (500 ppm), the velocity profile shows large S-shape. The velocity profile does not change very much, even if the Reynolds increases. The shape parameter with surfactant solutions decreases slightly comparing that of tap water at Re < 92,000, The value of shape parameter H with surfactant solution shows 1.66 < H < 2.32.
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Cardenas, Ruander, und Vinod Narayanan. „A Numerical Study of Ammonia-Water Absorption Into a Constrained Microscale Film“. In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-67021.
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A one-dimensional, steady state, semi-empirical model of an ammonia-water microscale bubble absorber is presented. The geometry consists of a microchannel through which a solution of ammonia-water flows. Ammonia vapor is injected through one of the walls of the channel. A counter flowing coolant solution removes the heat generated due to absorption from the opposite wall. The 1-D, steady state species and energy transport equations are solved to yield, along the length of the channel, concentration and temperature profiles of the solution stream and the temperature profile of the coolant fluid stream. Values for the overall heat transfer coefficient from experimental results are used in this model. A parametric study of fluid and geometrical parameters based on the model is presented. The varied fluidic parameters include the mass flow rates of the weak solution, coolant, and vapor, the inlet coolant temperature, and the weak solution concentration. Two variations of the vapor distribution that resulted from a geometrical variation of the porous plate are considered: (a) variation in length of the non-porous section, and (b) variation in the number of intermittent sections in which there was no injection of vapor. Trends of the parametric study were consistent with those of experiments. A salient result of the parametric study indicates that incomplete absorption occurs with an increase in weak solution flow rate due to the decrease in residence time within the microchannel for absorption. At a specific fixed flow condition, a single porous section followed by a non-porous section provides the optimal vapor distribution for absorption within the channel. The length of this non-porous section for optimal absorption within the channel is also determined using the model.
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Ozar, Basar, Jae Jun Jeong, Abhinav Dixit, Jose Enrique Julia´, Takashi Hibiki und Mamoru Ishii. „Local and Area-Averaged Flow Structure of Air-Water Two-Phase Flow in a Vertical Annulus“. In 16th International Conference on Nuclear Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/icone16-48067.
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The flow structure of gas-liquid two-phase flow has been investigated in a vertical annulus channel. The annulus consisted of a geometry where the inner diameter was 19.1 mm and the outer diameter was 38.1 mm. The total height of the test section was 4.37 m. Experiments were conducted for nineteen inlet flow conditions. These flow conditions covered bubbly, cap-slug, and churn-turbulent flows. The local flow parameters, such as void fraction, interfacial area concentration, and bubble interface velocity, were measured at nine radial positions within the gap of the annulus at z/Dh = 230 of the test section. Radial distributions of these parameters were interpreted in terms of turbulent velocity profile, lift and wall forces. In addition, the local measurements were used to calculate distribution parameter, C0 in drift-flux model, and area averaged interfacial area concentration. Ishii’s (1977) model was modified and a new correlation of C0 was proposed based on the experimentally obtained C0 values. The area-averaged interfacial area concentration (IAC) values were compared with the most widely used models (Ishii and Mishima, 1980; Spore et al., 1983; Hibiki and Ishii, 2002). The advantages and drawbacks of these models were highlighted.
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Deuel, Lloyd E., und George H. Holliday. „Soil Moisture Analyses to Locate Shallow Ground Water: A Solution to a Vexing Problem“. In ASME 2001 Engineering Technology Conference on Energy. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/etce2001-17089.
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Abstract EPA and most States require a hydrogeologic assessment of contaminated sites to identify and characterize the upper most aquifer and potential pathways for contamination. The advancement of soil borings, followed by the completion of monitoring wells in boreholes is often the first step in direct site characterization. These monitoring wells have the potential to contaminate deeper ground waters; if the site has a contaminated seasonal perched water table from which water is allowed to enter the borehole before the well is cased. This condition is particularly troublesome when a temporary monitoring well is used for assessment purposes and contaminate concentrations are compared to maximum concentration limits (MCLs) for drinking water. A seasonal or permanent perched water table may be contaminated, but separated and protected from deeper useable groundwater by the unsaturated ‘vadose’ zone. The lack of saturation in the vadose naturally restricts the movement of water due to unsaturated flow dynamics and the corresponding flux of soluble constituents irrespective of attenuating reactions with soil. This paper presents a method of distinguishing saturated zones from unsaturated zones by comparative analysis of existing soil moisture and the field capacity or 33.3 kPa (1/3 bar) moisture equivalent. Moisture measurements are made for core samples collected in continuous fashion to a selected depth and sample interval determined by the use and sensitivity required in the interpretation of the data. Soil moisture profiles in conjunction with geophysical measurements of bulk density and particle density allow determination of volume wetness and degree of saturation. Additionally, these data are used to assess the movement of water in the soil profile and potential contaminant migration to useable groundwater. The authors have used this technique to differentiate vadose zones sandwiched between seasonal perched water and even thin continuous saturated zones from useable groundwater. Actual field data are presented to demonstrate the ease with which false positive results are generated that portends an adverse impact to groundwater and the need for costly risk reduction analysis or remediation.
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Matoušek, Václav, Jan Krupička, Jiří Konfršt und Pavel Vlasák. „Effect of Pipe Inclination on Solids Distribution in Partially Stratified Slurry Flow“. In ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ajkfluids2019-5397.
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Abstract Partially stratified flows like flows of sand-water slurries exhibit non-uniform distribution of solids (expressed as a vertical profile of local volumetric concentration) in a pipe cross section. The solids distribution in such flows is sensitive to pipe inclination. The more stratified the flow is the more sensitive its concentration profile is to the pipe slope. In general, the distribution tends to become more uniform (less stratified) if the inclination angle increases from zero (horizontal pipe) to positive values (ascending pipe) up to 90 degree (vertical pipe). In a pipe inclined to negative angles (descending pipe) the development is different. The flow tends to stratify more if it changes from horizontal flow to descending flow down to the angle of about −35 degree. If the angle further decreases towards −90 degree, then the flow becomes less stratified reaching uniform distribution at the vertical position. This also means that the same flow exhibits a very different degree of stratification in ascending and descending pipes inclined to the same (mild) slope say between ±10 and ±40 degree. The rather complex development of the solids distribution with the variation of the inclination of pipe is insufficiently documented experimentally and described theoretically in predictive models for a concentration profile in partially stratified flow. In order to extend the existing limited data set with experimental data for partially stratified flow of medium sand slurry, we have carried out a laboratory experiment with the slurry of narrow graded fraction of sand with the mean grain size of 0.55 mm in our test loop with an invert U-tube inclinable to arbitrary angle between 0 and 90 degree. A pipe of the loop has an internal diameter of 100 mm. Both legs of the U-tube have a measuring section over which differential pressures are measured. Radiometric devices mounted to both measuring sections sense concentration profiles across a pipe cross section. Furthermore, the discharge of slurry is measured in the test loop. In the paper, experimental results are presented for various inclination angles with a small step between 0 and ±45 degree and a development in the shape of the concentration profiles with the changing inclination angle is analyzed. For the analysis, it is critical to distinguish between suspended load and contact load in the flow as the two loads tend to react differently to the flow inclination. The measured concentration profiles and pressure drops are compared with predictions by the layered model adapted for taking the flow inclination into account.
Berichte der Organisationen zum Thema "Water concentration profile"
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Bridges, Todd, Sandra Newell, Alan Kennedy, David Moore, Upal Ghosh, Trevor Needham, Huan Xia, Kibeum Kim, Charles Menzie und Konrad Kulacki. Long-term stability and efficacy of historic activated carbon (AC) deployments at diverse freshwater and marine remediation sites. Engineer Research and Development Center (U.S.), November 2020. http://dx.doi.org/10.21079/11681/38781.
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A number of sites around the United States have used activated carbon (AC) amendments to remedy contaminated sediments. Variation in site-specific characteristics likely influences the long-term fate and efficacy of AC treatment. The long-term effectiveness of an AC amendment to sediment is largely unknown, as the field performance has not been monitored for more than three years. As a consequence, the focus of this research effort was to evaluate AC’s long-term (6–10 yr) performance. These assessments were performed at two pilot-scale demonstration sites, Grasse River, Massena, New York and Canal Creek, Aberdeen Proving Ground (APG), Aberdeen, Maryland, representing two distinct physical environments. Sediment core samples were collected after 6 and 10 years of remedy implementation at APG and Grasse River, respectively. Core samples were collected and sectioned to determine the current vertical distribution and persistence of AC in the field. The concentration profile of polychlorinated biphenyls (PCBs) in sediment pore water with depth was measured using passive sampling. Sediment samples from the untreated and AC-treated zones were also assessed for bioaccumulation in benthic organisms. The data collected enabled comparison of AC distribution, PCB concentrations, and bioaccumulation measured over the short- and long-term (months to years).