Literatura académica sobre el tema "Gradient salin"
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Artículos de revistas sobre el tema "Gradient salin"
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Dixon, D. A., J. Graham y M. N. Gray. "Hydraulic conductivity of clays in confined tests under low hydraulic gradients". Canadian Geotechnical Journal 36, n.º 5 (23 de noviembre de 1999): 815–25. http://dx.doi.org/10.1139/t99-057.
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Clay barriers normally function at hydraulic gradients much lower than are commonly used in laboratory tests for hydraulic conductivity. This paper describes low-gradient tests on compacted illite, Na-bentonite, and sand-bentonite specimens at a range of dry densities. The tests examined the effects of deionized or saline pore fluid, the initial degree of saturation at the time of compaction, and back-pressuring to achieve saturation during permeation. No "critical" or "threshold" gradients were observed. In low-density materials, "transitional" gradients defined two separate regions of Darcian flow. Low flow rates and low hydraulic conductivities were associated with hydraulic gradients below the transitional gradient. Higher conductivities were associated with gradients above the transitional gradient. Hydraulic conductivities decreased with increasing initial density. They appeared independent of initial degree of saturation or back-pressuring. Tests on Na-rich bentonite showed that deionized and saline permeants produced similar hydraulic conductivities. Measured hydraulic conductivities were in reasonable agreement with values computed using the Poiseuille and Kozeny-Carman equations. Key words: hydraulic conductivity, gradient, Darcian, illite, bentonite.
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Chittur K, Subramaniam, Aishwarya Chandran, Ashwini Khandelwal y Sivakumar A. "Energy Conversion using electrolytic concentration gradients". MRS Proceedings 1774 (2015): 51–62. http://dx.doi.org/10.1557/opl.2015.758.
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ABSTRACTSalinity gradient is an enormous source of clean energy. A process for potential generation from an ionic concentration gradient produced in single and multicell assembly is presented. The ionic gradient is created using a fuel cell type cell with a micro-porous ion exchange membrane, both anionic (AEM) and cationic (CEM). Various salinity gradients, Salt : Fresh, from 100 : 0 to 16000 : 0 was established using NaCl solution, in the electrode chambers. A potential of 20 mV/cm to 25 mV/cm can be realized at ambient temperatures and pressures for a bipolar AEM/CEM cell. The performance was optimized for various static and dynamic flow rates of the saline and fresh water. The cell performance can further be optimized for Membrane Electrode System (MES) morphology. A multicell unit was assembled and the results presented for various conditions like concentration gradients, flow rates and pressure. The thermodynamic and electrical efficiency needs to be evaluated for various gradients and flow rates. The relation with number of valance electrons/ ion and the potential generated changes for various dynamic condition of salinity. The higher the salinity gradient the larger is the potential generated. This is limited by the membrane characteristics. There exists a monotonic relation between the number of valence electron/ion/unit time and the potential generated up to about 16000 concentration. The membrane characteristics have been studied for optimal ion crossover for various gradients and flow. The graph between ln (gradient) versus Voltage provides insights into this process. This presents a very cost effective and clean process of energy conversion.
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KASYANOV, A. E. y ISMAIL KHEBA ISMAIL KHEBA. "INSTALLATION FOR PHYSICAL MODELING OF SALINE SOILS WASHING". Prirodoobustrojstvo, n.º 2 (2021): 31–35. http://dx.doi.org/10.26897/1997-6011-2021-2-31-35.
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Gradients of salts concentrations of the soil solution, rinsing water pressures, filtration coefficients determine the flow intensity of the salt solutions in the aeration zone. There are known a lot of software for calculating the motion of salt solutions in the porous medium. To assess the accuracy of calculations of the salts movement in the soil, the data of gradient measurements are used. The implementation of the known methods of physical modeling on the soil monoliths mounted according to Astapov, lysimetric installations, in experimental leaching of saline soils in the field requires significant material investments, labor and time. Minimum material and labor costs are required for the assembly and use of the proposed design of the installation for physical modeling of saline soil washing. A working prototype of the installation has been developed. It includes piezometers, a case, units of piezometers connection, sampling of soil moisture combined with soil electrodes, equalizing drain, rotating part of the case. Piezometers, drains and connecting hoses, soil moisture sampling unit. The installation case is assembled of separate branch pipes equipped with necks and sealing rings. Filtration investigations and gradient measurements of the salts movement are carried out on the installation. The tests of the installation prototype were fulfilled in the field on the sand pit reclamation map located in the floodplain of the Gzhelka and Moskva rivers of the Ramensk region of the Moscow area. The profile filtration coefficients measured at the installation – 2.33 ± 0.031 m / day and in the field conditions – 2.36 ± 0.041 m / day do not differ significantly.
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Scheifele, Benjamin, Rich Pawlowicz, Tobias Sommer y Alfred Wüest. "Double Diffusion in Saline Powell Lake, British Columbia". Journal of Physical Oceanography 44, n.º 11 (1 de noviembre de 2014): 2893–908. http://dx.doi.org/10.1175/jpo-d-14-0070.1.
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Abstract Powell Lake contains a deep layer of relic seawater separated from the ocean since the last ice age. Permanently stratified and geothermally heated from below, this deep layer is an isolated geophysical domain suitable for studying double-diffusive convection. High-resolution CTD and microstructure measurements show several double-diffusive staircases (Rρ = 1.6 to 6) in the deep water, separated vertically by smooth high-gradient regions with much larger density ratios. The lowest staircase contains steps that are laterally coherent on the basin scale and have a well-defined vertical structure. On average, temperature steps in this staircase are 4 mK, salinity steps are 2 mg kg−1, and mixed layer heights are 70 cm. The CTD is capable of measuring bulk characteristics of the staircase in both temperature and salinity. Microstructure measurements are limited to temperature alone, but resolve the maximum temperature gradients in the center of selected laminar interfaces. Two different algorithms for characterizing the staircase are compared. Consistent estimates of the steady-state heat flux (27 mW m−2) are obtained from measurements above and below the staircase, as well as from microstructure measurements in the center of smooth interfaces. Estimates obtained from bulk interface gradients underestimate the steady-state flux by nearly a factor of 2. The mean flux calculated using a standard 4/3 flux law parameterization agrees well with the independent estimates, but inconsistencies between the parameterization and the observations remain. These inconsistencies are examined by comparing the underlying scaling relationship to the measurements.
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Amin, Fatima, Abdul Sattar Shaikh, Sohail Khan Bangash, Amber Kamran, Nida Rafique, Mujeeb Ur Rehman y Najma Patel. "Correlation between Intraoperative Direct and Transesophageal Echocardiographic Assessment of Right Ventricular Outflow Tract Pressure Gradient in Patients Undergoing Tetralogy of Fallot Repair". Pakistan Heart Journal 56, n.º 1 (1 de abril de 2023): 92–96. http://dx.doi.org/10.47144/phj.v56i1.2484.
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Objectives: The objective of this study was to determine the correlation between intraoperative direct (needle) and transesophageal echocardiographic (TEE) assessment of right ventricular outflow tract (RVOT) pressure gradient in patients undergoing Tetralogy of Fallot (TOF) repair. Methodology: A total of 100 patients underwent for TOF repair were included. After completion of surgery and successful weaning from cardiopulmonary bypass, the TEE derived RVOT gradients were obtained from, the midesophageal ascending aortic short axis (AA Sax) view, upper esophageal aortic arch short axis (Arch Sax) view and trans-gastric RV outflow (TG RV outflow) view. Direct (needle) derived pressures from right ventricular (RV) and pulmonary artery (PA) were obtained by surgeon using a saline filled pressure transducer system. Correlation coefficient was computed between intraoperative direct and TEE assessment of RVOT gradient was evaluated. Results: In the sample of 100 patients, 41% were females and median age was 8 [5-11] years. The TEE derived RVOT gradients obtained in AA Sax, Arch Sax and TG RV outflow view were 26.46±6.98, 26.60±6.55, and 22.64±6.21 mmHg, respectively. Intraoperative RVOT pressure gradient was 19.05±8.9 mmHg. The correlation between intraoperative direct (needle) and TEE assessment of RVOT pressure gradient obtained in AA Sax, Arch Sax, and TG RV outflow view were 0.588 (p<0.001), 0.283 (p<0.001), and 0.383 (p<0.001), respectively. Conclusion: Intraoperative TEE assessment of RVOT pressure gradient showed a moderate correlation with the direct (needle) assessment. The ascending aorta short axis view was found to be the superior esophageal view.
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Niinemets, Ülo, Aljona Lukjanova, Ashley D. Sparrow y Matthew H. Turnbull. "Light-acclimation of cladode photosynthetic potentials in Casuarina glauca: trade-offs between physiological and structural investments". Functional Plant Biology 32, n.º 7 (2005): 571. http://dx.doi.org/10.1071/fp05037.
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Many arid and saline habitat species possess sparse canopies with cylindrical foliage that is considered relatively invariable along environmental gradients. However, even in sparse canopies strong gradients of light develop between the canopy top and bottom. We studied structural and photosynthetic acclimation to within-canopy light gradient in Casuarina glauca Sieb. ex Spreng., the photosynthetic organs of which are cylindrical cladodes. Seasonal average integrated quantum flux density (Qint) varied 25-fold between the canopy top and the canopy bottom. Cladode cross-sectional shape was unaffected by irradiance, but cladode dry mass per unit total area (MA) varied 2-fold within the canopy light gradient. This resulted primarily from light-dependent changes in cladode thickness (volume to total area ratio,V / AT) and to a lesser extent from changes in cladode density (D, MA = DV / AT). Nitrogen content, and the volume of mesophyll per unit surface area increased with increasing Qint and V / AT, resulting in positive scaling of foliage photosynthetic potential (capacity of photosynthetic electron transport and maximum Rubisco carboxylase activity per unit area) with light. However, nitrogen content per unit dry mass and the volume fraction of mesophyll decreased with increasing irradiance. This was explained by greater fractional investment in mechanical tissues in cladodes with greater volume to surface area ratio. This trade-off between photosynthetic and support investments reduced the cladode photosynthetic plasticity. Our study demonstrates a significant acclimation potential of species with cylindrical foliage that should be included in larger-scale carbon balance estimations of arid and saline communities.
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Gran, M., J. Carrera, S. Olivella y M. W. Saaltink. "Modeling evaporation processes in a saline soil from saturation to oven dry conditions". Hydrology and Earth System Sciences Discussions 8, n.º 1 (18 de enero de 2011): 529–54. http://dx.doi.org/10.5194/hessd-8-529-2011.
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Abstract. Thermal, suction and osmotic gradients interact during evaporation from a salty soil. Vapor fluxes become the main water flow mechanism under very dry conditions. A coupled nonisothermal multiphase flow and a reactive transport model of a salty sand soil was developed to study such an intricate system. The model was calibrated with data from an evaporation experiment (volumetric water content, temperature and concentration). The retention curve and relative permeability functions were modified to simulate oven dry conditions. Experimental observations were satisfactorily reproduced, which suggests that the model can be used to assess the underlying processes. Results show that evaporation is controlled by heat, and limited by salinity and liquid and vapor fluxes. Below evaporation front vapor flows downwards controlled by temperature gradient and thus generates a dilution. Vapor diffusion and dilution are strongly influenced by heat boundary conditions. Gas diffusion plays a major role in the magnitude of vapor fluxes.
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Maheswaran, P. A., S. Satheesh Kumar y T. Pradeep Kumar. "Intra annual Variability of the Arabian Sea high salinity water mass in the South Eastern Arabian Sea during 2016 17". Defence Science Journal 69, n.º 2 (6 de marzo de 2019): 149–55. http://dx.doi.org/10.14429/dsj.69.14217.
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Intra-annual variability of the Arabian Sea high salinity water mass (ASHSW) in the South Eastern Arabian Sea (SEAS) and Gulf of Mannar (GoM) are addressed in this paper by utilisng the monthly missions carried out onboard INS Sagardhwani during 2016-17. Our observations revealed that the ASHSW was evident along the SEAS irrespective of seasons, whereas in the GoM the presence of ASHSW was observed during winter. The processes such as downwelling/up-welling, coastal currents, intrusion of low saline waters, stratification are clearly affects the spreading of the ASHSW. The characteristics such as core salinity value, depth and thickness of ASHSW exhibited remarkable spatio-temporal variability. Lateral mixing with the low saline waters in the region during winter reduces its core salinity. The intrusion of low saline waters was clearly seen upto 15 ON but the intrusion of low saline waters is not flowing through the GoM. The interface between the ASHSW and the prevailing low saline waters showed strong horizontal gradients of salinity. The presence of the ASHSW makes difference in the SLD and the below layer gradient which is sufficient to complicate or influence sound transmission. The spatio temporal variability of the ASHSW and its acoustic relevance are documented in this paper.
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Sánchez, G. y F. Méndez. "Power generation cell driven by osmotic pressure in microchannels with hydrophobic surfaces and viscoelectric effects". Journal of Physics D: Applied Physics 55, n.º 25 (1 de abril de 2022): 255501. http://dx.doi.org/10.1088/1361-6463/ac5ef1.
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Abstract A theoretical study that explores power generation via streaming potential and osmotic gradients is proposed. The system is compounded by an osmotic membrane that has different saline concentrations on each side. This concentration gradient promotes a volumetric flux rate inside a microchannel with parallel plates whose surfaces are made of modified hydrophobic fumed silica, thus, the no-slip condition is no longer sustained. Aside from these characteristics, we consider viscoelectric effects in the analysis. The set of equations is written in dimensionless variables, which are solved with integrodifferential methods, permitting us to obtain semi-analytical solutions for velocity, pressure fields, and the most important: the electric potential generated for the system. This setup converts concentration gradients into electric energy in the form of streaming potential. Besides, we demonstrate that hydrophobic surfaces promote a greater induced streaming potential, nonetheless, for high potentials appears a saturation phenomenon which avoids the growth of the induced electric potential no matter how large the slip-conditions could be.
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Arenson, Lukas U. y Dave C. Sego. "The effect of salinity on the freezing of coarse-grained sands". Canadian Geotechnical Journal 43, n.º 3 (1 de marzo de 2006): 325–37. http://dx.doi.org/10.1139/t06-006.
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Unfrozen water is very important because it has a significant influence on the mechanical response of a frozen soil. It is particularly important to know if the water is available as free water or if it is bonded to the solid particles. A simple experimental setup was used to observe the freezing process of a coarse-grained soil under controlled freezing gradients and salinities. A fluorescent tracer helped to determine the location of the unfrozen water during freezing. Depending on the salinity and the thermal gradient, pockets of unfrozen water with a much higher salt concentration were trapped in pores under increased pore pressures. Even at salinities as low as 2 g/L, spicular ice crystals were identified with channels containing unfrozen water between the ice crystals. The experiments further indicate that the unfrozen water in coarse-grained frozen soils is in the middle of the pore space compared to the unfrozen water film that immediately surrounds fine-grained saline or non-saline soil particles.Key words: frozen soil, salinity, frost penetration, thermal conductivity.
Tesis sobre el tema "Gradient salin"
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Wu, Nan. "Capacitive reverse electrodialysis cells for osmotic energy harvesting : Toward real brines and power enhancement". Electronic Thesis or Diss., Université Paris sciences et lettres, 2024. http://www.theses.fr/2024UPSLS019.
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Face aux problèmes de réchauffement climatique, trouver des ressources énergétiques propres et durables pour remplacer les combustibles fossiles conventionnels est d'une importance capitale. L'énergie osmotique demeure une ressource énergétique inexploitée avec un potentiel significatif. Dans ce travail, nous parvenons à une conversion efficace de l'énergie osmotique en électricité grâce à un processus de mélange bien contrôlé utilisant un système d'électrodialyse inverse capacitif (CRED). Il est démontré qu'un écart substantiel de densité de puissance existe entre le système CRED et la valeur maximale théorique, principalement en raison de l'efficacité de conversion faible du flux ionique-électronique dans les électrodes capacitifs. Pour pallier cette limitation, nous proposons la stratégie de boosting pour optimiser le régime de fonctionnement du système CRED. Des expériences et des modélisations confirment une amélioration de la performance énergétique du système CRED. Pour avancer vers des applications réelles, nous évaluons les performances du système CRED sous des solutions composées de mélanges ioniques complexes. Contrairement à la chute significative de la densité de puissance observée dans les systèmes RED classiques, le système CRED ne présente qu'une légère diminution lorsqu'il est soumis à des solutions avec un mélange d'ions divalents. Ce phénomène est attribué au renversement périodique des solutions dans les compartiments, qui atténue l'effet d'empoisonnement de la membrane. Ce résultat est ensuite validé par des tests à long terme avec des solutions réelles. Pour généraliser le système CRED dans un spectre plus large, nous proposons une cellule de gradient de pH avec des électrodes de MnO2 à pseudo-capacité. Elle utilise l'énergie osmotique établie dans un processus de capture de CO2 basé sur un électrolyte et vise à réduire le coût global du processus de capture de carbone. La cellule de gradient de pH présente une augmentation inattendue de la densité de puissance sous la stratégie de boosting. Cela est dû à la contribution de tension supplémentaire des électrodes en raison du changement de couverture fractionnelle lié aux réactions d'oxydoréduction. Cependant, elle reste dans le cadre du régime capacitif et est bien décrite par une modélisation CRED adaptéeGiven the global warming issues, finding clean and sustainable energy resources to replace conventional fossil fuels is of paramount importance. Osmotic energy remains an untapped energy resource with significant potential. In this work, we achieve efficient conversion of osmotic energy into electricity through a well-controlled mixing process using a capacitive reverse electrodialysis (CRED) system. It is demonstrated that a substantial power density gap exists between the CRED system and the theoretical maximum value, primarily due to the low ionic-electronic flux conversion efficiency in capacitive electrodes. To address this limitation, we propose the boosting strategy to optimize the working regime of the CRED system. Both experiments and modeling confirm an enhanced energy performance of the CRED system. To advance towards real-world applications, we assess the performance of the CRED system under solutions composed of complex ion mixing. In contrast to the significant power density drop observed in classic RED systems, the CRED system exhibits only a minor decrease when subjected to solutions with divalent ion mixing. This phenomenon is attributed to the periodic water chamber reversal, which mitigates the membrane poisoning effect. This result is further validated through long-term testing with real-world solutions. To generalize the CRED system into a broader spectrum, we propose a pH gradient cell with MnO2 electrodes of pseudo capacitance. It uses the osmotic energy established within an electrolyte based CO2 capturing process and aims to reduce the overall cost of carbon capturing process. The pH gradient cell presents unexpected power density increase under boosting strategy. This is due to the additional electrode voltage contribution due to fractional coverage change related to redox reactions. However, it stays in the framework of capacitive regime and remains well described by an adapted CRED modeling
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Lavaine, Catherine. "Evaluation des capacités biotechniques de boutures de Salicaceae et Tamaricaceae sur un gradient de sécheresse". Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2013. http://tel.archives-ouvertes.fr/tel-00969038.
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Le phénomène naturel d'érosion des berges peut menacer des infrastructures humaines. Des protections végétales peuvent être installées afin de mimer les dynamiques de végétation et armer la berge grâce aux racines. Cependant, les changements climatiques globaux sont susceptibles d'entraîner et d'aggraver les sécheresses, ce qui va stresser les végétaux présents et compromettre la bonne réussite des ouvrages de génie végétal. La principale question est donc " Quelles sont les caractéristiques biotechniques et les facultés d'acclimatation à la sécheresse de boutures de Salicaceae et Tamaricaceae, espèces utilisées ou potentiellement utilisables en génie végétal ? ". L'étude de différentes populations d'espèces classiquement utilisées que sont les saules démontre une résistance à la sécheresse plus efficace des populations méridionales tandis que les productions de biomasses restent plus élevées chez les populations septentrionales. L'étude des traits biotechniques et du comportement racinaire d'espèces potentielles appartenant aux Tamaricaceae (Tamarix gallica et Myricaria germanica) montre un taux élevé de reprise au bouturage, une forte production de biomasses et une stratégie de prospection racinaire différente des saules, ce qui leur confère une résistance à la sécheresse accrue. Ceci confirme une utilisation possible de ces espèces dans des ouvrages de génie végétal soumis à sécheresse.
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Douar, Adnane. "Recherche de matériaux isolants pour la conception d'une nouvelle génération de connecteurs électriques haute tension : influence de la pollution sur les phénomènes de décharges partielles du contournement et de claquage". Thesis, Ecully, Ecole centrale de Lyon, 2014. http://www.theses.fr/2014ECDL0046/document.
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Dans le présent travail, nous abordons une problématique essentielle liée aux accessoires des lignes électriques et plus particulièrement au connecteur à perforation d’isolant (TTDC 45501 FA), commercialisé par la société Sicame située à Arnac-Pompadour (Corrèze). Ce produit permet d’effectuer des dérivations de courant en moyenne tension gainé HTA entre 15 et 25kV. Cependant, il devient nécessaire de concevoir une nouvelle génération de connecteurs capable de fonctionner à une tension de 52 kV en raison de la constante augmentation des besoins en électricité. En réalité, le principal souci concernant ces produits réside dans l’apparition de décharges partielles dans le volume constitué par la matière isolante (polyamide 6 chargée à 50% en poids de fibres de verre). Ces décharges engendrent un vieillissement prématuré du produit sous l’action conjuguée d’une atmosphère corrosive (brouillard salin) et d’un champ électrique. Ainsi, l’objectif de la présente thèse est de faire, dans un premier temps, un choix approprié de matériaux isolants parmi des polymères thermoplastiques, thermodurcissables époxydes ou élastomères en EPDM, capables de résister à plusieurs contraintes : thermique, électrique, mécanique, chimique et climatique. La partie expérimentale concerne, tout d’abord, la mesure de la tension de contournement, de l’activité des décharges partielles se propageant à la surface des matériaux isolants et de la tension de claquage, en tension alternative (A.C.). Pour cela, des échantillons polymères qui comportent des surfaces planes ou des surfaces pourvues de protubérances ont été moulés en vue de comparer leur comportement diélectrique en présence d’atmosphères polluées de type brouillard salin; ces mesures sont nécessaires pour effectuer un choix approprié du matériau à intégrer dans le connecteur. Par la suite, l’étude et la caractérisation optique et électrique de décharges glissantes, se propageant en surface de divers matériaux polymères, en tension impulsionnelle (L.I.) pour les deux polarités (positive et négative) et pour deux types de champ électrique (normal et tangentiel) sont présentées pour le cas d’une interface solide/air. La mesure de la longueur finale des décharges glissantes et la visualisation de l’onde de courant sont les deux paramètres principaux pour différencier les caractéristiques des matériaux utilisés. L’ensemble des résultats de mesures a permis de sélectionner les résines époxydes cyclo-aliphatiques (CEP) comme candidates potentielles pour la conception d’une nouvelle génération de connecteurs. De plus, la simulation du champ électrique, à l’aide du logiciel Flux 2D/3D, sur le connecteur électrique (TTDC 45501FA) a permis d’aboutir à la proposition d’un prototype de connecteur présentant une nouvelle géométrie et pouvant fonctionner à 52kVIn the present study, we deal with an essential problem related to electrical lines accessories and more particularly to piercing connectors (TTDC 45501FA) commercialized by a private company named Sicame and which is located in Arnac-Pompadour (Corrèze, France). This product/accessory is designed to provide power diversions on medium voltage live lines HVA operating between 15 and 25kV. However, it becomes required to design a new generation of piercing connectors able to operate on 52kV live lines because of the electrical power demands that are steadily increasing. Actually, the main concerns about these products are the occurrence of partial discharges within the insulating material volume (polyamide 6 containing 50%wt of glass fibers). Most of the time, these discharges induce an early ageing process of the accessory under the combined effects of a corrosive environment (as salt fog) and an electric field threshold. Thus, the main objective of the present Ph.D. thesis is to carry out an appropriate choice of insulating materials among several tested polymers such as thermoplastics and thermosetting epoxy resins and EPDM elastomers that are capable of withstanding several constraints: thermal and electrical and mechanical and chemical conditions. The experimental section is focusing on the measurements of flashover voltage and partial discharges activity propagating on polymeric surfaces and breakdown voltage within material bulks under A.C voltage. That is why polymeric samples with plane surfaces and textured surfaces are molded to compare their resistance to partial discharges when being subjected to polluted environments such as salt fog; these measurements are necessary to choose the suitable materials for the required application to be integrated in the new generation of connectors. Then, the optical and electrical characterization results of creeping discharges propagating on several polymeric surfaces under lightning impulse (L.I.) voltage with its both polarities (positive and negative) and for two kinds of applied electric field (normal and tangential) are presented in the case of solid/air interfaces. Final length measurements of creepage discharges are the main parameter for distinguishing material properties. The whole obtained results (under AC and LI voltages) allow us to point out the cycloaliphatic epoxy resins as potential candidates to the conception of a new generation of piercing connectors. In addition, the electric field simulation and modelling of the TTDC 45501FA connector by using the Flux 2D/3D software seems to be helpful to design a connector prototype which exhibits a new geometry and is able to reach a voltage level that equals 52kV
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Latreille, Anne. "Diversité et adaptation des arbres forestiers : analyse de gradients altitudinaux et de transplantations croisées chez le sapin pectiné". Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0012/document.
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Les populations répondent aux variations de l'environnement par une adaptation dans un premier temps plastique puis, à plus long terme, génétique. Cette faculté à évoluer est aujourd'hui confrontée à un changement climatique à la fois très rapide et de grande ampleur. L'étude de 15 provenances de sapin pectiné (Abies alba Mill.) réparties sur trois gradients altitudinaux (~ 900 à 1600 m) nous a permis d'évaluer par des approches de dendroécologie et de génétique quantitative leurs caractéristiques phénotypiques et génétiques ainsi que leur potentiel d’acclimatation et d’adaptation. La croissance radiale de 129 arbres adultes répartis le long des gradients a été analysée. Six traits adaptatifs liés à la croissance, la phénologie et la survie ont été mesurés sur 57 descendances maternelles issues de ces provenances et installées en transplantations réciproques dans neuf jardins communs répartis sur les gradients. Les résultats montrent que (i) la diversité phénotypique des populations est principalement due à l’environnement (i.e. plasticité phénotypique), (ii) l’ensemble des traits mesurés sur les semis sont sous contrôle génétique, (iii) les populations étudiées ne semblent pas avoir été soumises à des sélections différenciées (iv) le sapin est très sensible à la sécheresse estivale, d’autant plus si elle se répète d’une année sur l’autre. L’ensemble de ces résultats suggère que les populations étudiées présentent de bonnes capacités d’adaptation mais qu’à plus ou moins court terme, le sapin pectiné est menacé d’extinction à basse altitude ou en marge sud de son aire de répartitionNatural populations respond to environmental variations firstly by plastic behavior, and, in the longer term, by genetic adaptation. Currently, the rapid and widespread climate change is challenging this ability to evolve. We studied 15 provenances of silver fir (Abies alba Mill.) distributed along three altitudinal gradients (~900 to 1600 m). We evaluated their phenotypic and genetic characteristics and their acclimation and adaptation potential, using dendroecological and quantitative genetic approaches. The radial growth of 129 adult trees distributed along the gradients were analyzed. Six adaptive traits related to growth, phenology and survival were measured on 57 maternal families collected from these provenances and planted following a reciprocal transplant experimental design in nine common gardens distributed along the gradients. The results show that (i) the phenotypic diversity of populations is mainly due to the environment (i.e. phenotypic plasticity), (ii) all the traits measured on seedlings are under genetic control, (iii) the studied populations do not appear to have been subjected to differentiated selections, (iv) silver fir is very sensitive to summer drought, especially when it is repeated over years. All these results suggest that studied populations have great adaptive capacities but that in the short term, silver fir is threatened by extinction on the southern or low elevation margins of its range
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Gilstrap, Matthew Coleman. "Renewable electricity from salinity gradients using reverse electrodialysis". Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49031.
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Renewable power generation from the controlled mixing of sea and fresh water is relatively unexplored when compared to the development for solar, wind, and other sustainable power alternatives. When global river discharge was taken into account, an estimated 2.6 TW of obtainable energy exists in untapped salinity gradients. Reverse electrodialysis is one proposed power-generating mechanism for harnessing energy from brackish environments and relies on the transport of aqueous salt ions through an apparatus of ion-exchange membranes. In this thesis, operational parameters, including flow direction, salinity composition, and membrane selectivity, are investigated. For optimal performance, I have employed counter-current flow mode with monovalent ion selective membranes and pure 0.5 M NaCl saline solution. The results show that a maximum open circuit voltage (OCV) level of 2.01 V is obtained with an active membrane area of 0.0756 m². The presence of multivalent ions in the feed solutions hinders OCV levels, but the effects are reduced with monovalent-selective membranes. Preliminary results are insightful; in order to increase the commercially viability of this technology, future work is needed to enhance the performance properties of the ion exchange membranes.
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Pinheiro, Marta Cristhiany Cunha. "AvaliaÃÃo de trÃs mÃtodos coproscÃpicos para diagnÃstico da esquistossomose mansÃnica em Ãrea de baixa endemicidade no Estado do CearÃ". Universidade Federal do CearÃ, 2010. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=5113.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorA Esquistossomose MansÃnica à uma doenÃa endÃmica em 76 paÃses e territÃrios. Em meados de 2003, calculou-se que 779 milhÃes de pessoas estavam dentro da populaÃÃo de risco para esquistossomose, e 207 milhÃes de pessoas estavam infectadas. O diagnÃstico laboratorial dessa parasitose pode ser realizado atravÃs de mÃtodos parasitolÃgicos de fezes, desde os mais clÃssicos (Kato-Katz), a alguns que ainda estÃo em fase de validaÃÃo. Este estudo foi realizado para avaliar dois novos mÃtodos coproscÃpicos para diagnÃstico da Esquistossomose MansÃnica, em moradores de uma Ãrea de baixa endemicidade no MunicÃpio de Maranguape, no Estado do CearÃ, utilizando o mÃtodo de Kato-Katz como referÃncia e a sorologia (ELISA) para a triagem dos pacientes. Foram desenvolvidas as seguintes etapas: Reconhecimento da Ãrea e divulgaÃÃo do projeto junto aos residentes na localidade; Visita domiciliar para assinatura do termo de consentimento livre e esclarecido e entrevista para coleta de dados epidemiolÃgicos; Coleta de sangue para realizaÃÃo do mÃtodo sorolÃgico; DistribuiÃÃo dos frascos para coleta de fezes, somente para os participantes que foram reativos no teste sorolÃgico; recebimento das amostras de fezes e realizaÃÃo dos mÃtodos coproscÃpicos e por fim, entrega dos resultados dos exames e tratamento dos indivÃduos positivos. Comparando-se os resultados obtidos pelo mÃtodo do Kato-Katz e do Gradiente SalÃnico viu-se que dos 13 positivos (23,2%) encontrados por ambos, 10 (76,9%) foram diagnosticados apenas atravÃs do Gradiente SalÃnico. Jà quando comparou-se o mÃtodo do Kato-Katz e do Helmintex, das 32 amostras analisadas, 16 foram positivos (50%) por ambos, porÃm, 12 (75%) destes indivÃduos foram diagnosticados apenas pelo Helmintex. E ao comparamos o mÃtodo do Gradiente SalÃnico com o Helmintex, nos 32 indivÃduos que realizaram estes, 17 (53%) foram positivos em ambas as tÃcnicas, sendo 11 (64,7%) positivos sà no Helmintex. Assim, os mÃtodos do Gradiente SalÃnico e Helmintex mostraram-se mais efetivos no diagnÃstico da esquistossomose mansÃnica na localidade em estudo, quando comparados ao Kato-Katz, porÃm diante da forma de execuÃÃo das tÃcnicas, as mesmas podem nÃo ser adequadas para grandes inquÃritos epidemiolÃgicos, mas para estudos pontuais em Ãreas onde o programa de controle nÃo consegue atingir os objetivos.
The Schistosomiasis is endemic in 76 countries and territories. In mid 2003, it was estimated that 779 million people were within the population at risk for schistosomiasis, 207 million people were infected. The laboratory diagnosis of schistosomiasis can be accomplished through methods for parasites, ranging from classics (Kato-Katz), a few that are still undergoing validation. This study was conducted to evaluate two coproscopic new methods for diagnosis of Schistosomiasis in residents of an area of low endemicity in Maranguape-CearÃ, using the Kato-Katz as a reference and serology (ELISA) for screening of patients. We developed the following steps: knowing the area and dissemination of the project with residents in the locality; Home visit to signing the consent form and interview to collect epidemiologic data, blood collection for performing the serological method, distribution of the bottles for feces, only for participants who were reactive in serological testing, collection of stool samples and carrying out the methods coproscopic and finally, delivery of results of examinations and treatment of positive individuals. Comparing the results obtained by the Kato-Katz method and salt gradient was seen that the 13 positive (23.2%) found by both, 10 (76.9%) were diagnosed only by the saline gradient. Even when we compared the method of Kato-Katz and Helmintex of the 32 samples analyzed, 16 were positive (50%) for both, however, 12 (75%) of these individuals were diagnosed only by Helmintex. And when comparing the method the saline gradient with Helmintex in 32 individuals who completed these, 17 (53%) were positive by both techniques, 11 (64.7%) positive only in Helmintex. Thus, the methods of the Saline Gradiente and Helmintex were more effective in the diagnosis of schistosomiasis in locus study, when compared to the Kato-Katz, but on the way of implementing the techniques, they may not be suitable for large surveys epidemiological, but for specific studies in areas where the driver fails to achieve the goals.
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Gamache, Isabelle. "Structure spatiale d'une population d'arbustes dioïques, Salix planifolia, le long d'un gradient successionnel en milieu dunaire subarctique". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq26208.pdf.
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Rosa, Inês Correia. "Ecologia de Atherina spp. ao longo do gradiente salino do canal de Mira (Ria de Aveiro)". Master's thesis, Universidade de Aveiro, 2008. http://hdl.handle.net/10773/780.
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Mestrado em Ecologia, Biodiversidade e Gestão de EcossistemasAs espécies Atherina boyeri Risso, 1810 e Atherina presbyter Cuvier, 1829, apesar de apresentarem características merísticas e morfométricas distintas, são por vezes difíceis de distinguir (nomeadamente em casos onde os peixes são pequenos ou estão danificados). Estas duas espécies apresentam também comportamento e ecologia distintos: A. presbyter é tipicamente marinha, podendo estar presente nas áreas mais salinas dos estuários, A. boyeri pode completar todo o seu ciclo de vida em água doce ou salobra sendo o seu comportamento nos estuários desconhecido. Pouco se sabe acerca da biologia destes peixes em Portugal, incluindo informação sobre as populações estuarinas e conservação. A amostragem foi efectuada no Canal de Mira (um dos braços principais da Ria de Aveiro, Portugal) em intervalos de 3 meses (Verão 2007- Primavera 2008) e foram determinados alguns parâmetros biométricos como comprimento total, GSI e alguns factores de condição. A Ria de Aveiro foi escolhida como caso de estudo de modo a determinar a influência do habitat, nomeadamente do gradiente de salinidade na distribuição e ecologia da população de peixe-rei. A distinção entre A. presbyter e A. boyeri foi feita com base em caracteres morfológicos e moleculares. O presente trabalho permitiu concluir que A. presbyter está presente em locais mais perto da boca do estuário enquanto A. boyeri tem preferência pelos locais no final do canal. As espécies coexistem em zonas intermédias (sainidade 5,5 a 22), com clara dominância de A. presbyter sobre A. boyeri. A presente população de peixe-rei reproduz-se durante a Primavera e Verão e os juvenis apenas se reproduzem na época reprodutora seguinte após o seu nascimento. Foi também possível concluir que há uma grande discrepância relativamente aos critérios merísticos sugeridos pela bibliografia usados para distinguir as duas espécies, pelo que é aqui proposto uma complementaridade entre critérios morfológicos e genéticos. ABSTRACT: Atherina boyeri Risso, 1810 and Atherina presbyter Cuvier, 1829, although distinct in meristic and morphometric characters, are sometimes difficult to differentiate, especially when small or injured fish are involved. They also exhibit distinct ecology and behaviour: while A. presbyter is typically marine, entering the more saline sections of estuaries, A. boyeri may complete its life cycle in fresh or brackish waters, although its behaviour in estuaries is unknown. Little is known on the biology of both species in Portugal, including the estuarine populations, and basic information needed for their conservation is missing. A sampling campaign was carried out in Canal de Mira (one of the main arms of Ria de Aveiro, Portugal) every three months (summer 2007 – spring 2008), and biometric features such as total length, GSI, and condition factors were determined. To avoid misidentifications, specimens were diagnosed with the aid of morphological and molecular characters. Ria de Aveiro was chosen as a case study to determine the influence of habitat, namely the salinity gradient, in the distribution and ecology of the sand smelts assemblage. We observed that A. presbyter occurred mostly downstream, while A. boyeri preferred the upper reaches of the estuary and both species cooccurred in the intermediate zones (salinity 5.5 to 22), with A. presbyter being dominant in this zone. Reproduction of Canal de Mira assemblage occurred during spring and summer, and juveniles only reproduced in the next reproductive season after their birth. We also concluded that there is a large overlap in scale counts between the two species, so a complementarity between morphological and genetic criteria is here proposed.
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Bessa, Michele Campos. "Estabelecimento de plantas nativas da caatinga em um gradiente de salinidade do solo, sob condições controladas". reponame:Repositório Institucional da UFC, 2012. http://www.repositorio.ufc.br/handle/riufc/18139.
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BESSA, Michele Campos. Estabelecimento de plantas nativas da caatinga em um gradiente de salinidade do solo, sob condições controladas. 2012. 89 f. Dissertação (Mestrado em engenharia agrícola)- Universidade Federal do Ceará, Fortaleza-CE, 2012.Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-06-24T19:33:22Z No. of bitstreams: 1 2012_dis_mcbessa.pdf: 6573208 bytes, checksum: 0fe38afd0ca62eb037f31aa8314dc0ed (MD5)
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Salinity is one of the abiotic stresses that most limits crop production because of its negative effects on plant growth and development. In areas degraded by salts it appears that the establishment of tree species is not easy, especially in rainfed crops and regions with very low precipitation. The objective of this study is to evaluate the establishment of twelve species of woody plants native to the Caatinga in a gradient of soil salinity in greenhouse, in order to obtain grants for the establishment of promising species under field conditions. The work was divided into two steps: 1. Growth and degree of salinity tolerance of twelve native species of Caatinga in a protected environment - The experimental design was randomized blocks in split plots with seedlings in the plot of twelve native species of the Caatinga (Aroeira, Ipê roxo, Mororó, Mulungu, Sabiá, Pau-mocó, Angico, Catanduva, Frei Jorge, Jurema branca, Tamboril, e Jurema preta) and subplots, the five levels of soil salinity (1.2, 2.7, 4.7, 6.7, 8,4 dS m-1), with five replicates. For moderate levels of soil salinity was found that all species are as tolerant or moderately tolerant to salinity. Considering the degree of reduction in total dry matter production, the highest level of salinity, it was observed that only the mastic proved to be tolerant to salinity (T); The Ipê and mulungu behaved as moderately tolerant (MT); the mororó and pau-mocó moderately susceptible (MS); most species, sabiá, angico, catanduva, frei jorge, jurema branca, jurema preta and tamboril, were classified as sensitive (S), with reductions of more than 60%. 2. Gas exchange and concentration of organic and inorganic solutes in six species native to the Caatinga under saline conditions - The design was randomized blocks in split plots with the plot six native species of Caatinga (Aroeira, Ipê roxo, Mororó, Mulungu, Sabiá e Pau-mocó,), which showed different degrees of salinity tolerance (step 1), and subplot five levels of soil salinity (1.2, 2.7, 4.7, 6.7, 8.4 dS m-1), with five replicates. Salinity caused reduction in leaf gas exchange, and this effect is independent of the species studied. However, observe a greater stomatal control and greater intrinsic efficiency of water use in species with higher degrees of salt tolerance, ie, aroeira, ipê roxo and mulungu. In the present study could not establish a clear relationship between the accumulation of organic solutes studied and salt tolerance of six species native to the Caatinga. However, observed a strong correlation between the Na/K and Na in the leaves and the degree of tolerance of species with species more tolerant of minor variations and presenting lower values with increasing soil salinity.
A salinidade é um dos estresses abióticos que mais limita a produção vegetal em razão de seus efeitos negativos no crescimento e desenvolvimento das plantas. Em áreas degradas por sais verifica-se que o estabelecimento de espécies arbóreas não é fácil, principalmente em cultivos de sequeiro e em regiões com precipitações muito baixas. O objetivo do presente trabalho consiste em avaliar o estabelecimento de doze espécies de plantas lenhosas nativas da Caatinga em um gradiente de salinidade do solo, em ambiente protegido, com vistas à obtenção de subsídios para estabelecimento de espécies promissoras em condições de campo. O trabalho foi dividido em duas etapas: 1. Crescimento e grau de tolerância à salinidade de doze espécies nativas da Caatinga em ambiente protegido - O delineamento utilizado foi de blocos ao acaso, no esquema de parcelas subdivididas tendo na parcela mudas de doze espécies nativas da Caatinga (Aroeira, Ipê roxo, Mororó, Mulungu, Sabiá, Pau-mocó, Angico, Catanduva, Frei Jorge, Jurema branca, Tamboril, e Jurema preta) e na subparcela, os cinco níveis de salinidade do solo (1,2; 2,7; 4,7; 6,7; 8,4 dS m-1), com cinco repetições. Para os níveis moderados de salinidade do solo verificou-se que todas as espécies se comportaram como tolerantes ou moderadamente tolerantes à salinidade. Considerando-se os graus de redução na produção de matéria seca total, no maior nível de salinidade, observou-se que apenas a aroeira mostrou-se tolerante à salinidade (T); o ipê roxo e mulungu responderam como moderadamente tolerantes (MT); o mororó e o pau mocó moderadamente sensíveis (MS); a maioria das espécies, sabiá, angico, catanduva, frei jorge, jurema branca, jurema preta e tamboril, foram classificadas como sensíveis (S), com reduções superiores a 60%; 2. Trocas gasosas e teores de solutos orgânicos e inorgânicos em seis espécies nativas da Caatinga sob condições de salinidade - O delineamento utilizado foi de blocos ao acaso, no esquema de parcelas subdivididas tendo na parcela seis mudas de espécies nativas da Caatinga (Aroeira, Ipê roxo, Mororó, Mulungu, Sabiá e Pau-mocó,), as quais apresentaram diferentes graus de tolerância à salinidade (etapa 1), e na subparcela os cinco níveis de salinidade do solo (1,2; 2,7; 4,7; 6,7; 8,4 dS m-1), com cinco repetições. A salinidade provocou redução nas trocas gasosas foliares, sendo esse efeito independente da espécie estudada. No entanto, se observa um maior controle estomático e maior eficiência intrínseca no uso da água nas espécies que apresentaram maiores graus de tolerância à salinidade, ou seja, aroeira, ipê roxo e mulungu. No presente estudo não foi possível estabelecer um relacionamento claro entre o acúmulo dos solutos orgânicos estudados e a tolerância à salinidade das seis espécies nativas da Caatinga. Porém, observou-se forte relação entre a relação Na/K e os teores de Na nas folhas e o grau de tolerância das espécies estudadas, com as espécies mais tolerantes apresentando menores variações e menores valores com o aumento da salinidade do solo.
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Olivella, Pastallé Sebastià. "Nomsothermal multiphase flow of brine and gas through saline media". Doctoral thesis, Universitat Politècnica de Catalunya, 1995. http://hdl.handle.net/10803/6261.
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Presentamos una formulación nueva para el análisis de problemas Termo-hidro-mecánicos en medios salinos. Esta formulación incluye, desde la obtención de ecuaciones de balance de masa, momento y energía hasta su resolución numérica, incluyendo la derivación de algunas ecuaciones constitutivas. El programa de calculo resultante (Code Bright) puede usarse para analizar problemas reales de sistemas de sellado construidos con agregados porosos de sal, que era la motivación original de este trabajo.Las ecuaciones de balance se han formulado teniendo en cuenta que en un medio salino existen tres especies o componentes mayoritarios. Estos son: la sal, el agua y el aire. Uno de los aspectos diferenciadores respecto a otros medios geológicos es que la fase sólida se disuelve a concentraciones elevadas en la fase liquida a la que se llama Salmuera. Otro aspecto interesante es la presencia de inclusiones de salmuera en la fase sólida. La disolución y precipitación de la sal da lugar a un mecanismo de deformación por fluencia. La forma de los granos de sal cambia por disolución en las zonas donde se concentran las tensiones y recristalizacion en las zonas de menor estado tensional. Además los granos también se deforman por el carácter muy dúctil del propio sólido cristalino. Hemos derivado una nueva ley constitutiva tensión deformación para los agregados porosos de sal, que se basa en acoplar una geometría idealizada de los granos con los mecanismos fundamentales de deformación.
Una vez que se ha desarrollado y verificado el programa de cálculo, este ha sido aplicado para el estudio de diferentes fenómenos. Presentamos el análisis de las variaciones de porosidad inducidas por gradientes de temperatura en agregados porosos de sal no saturados. Las diferencias de temperatura inducen un flujo de vapor que es contrarrestado por un flujo de salmuera. Este arrastra la sal disuelta y da lugar a un flujo de sal hacia zonas de temperatura más alta.
Libros sobre el tema "Gradient salin"
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Cipollina, Andrea y Giorgio Micale. Sustainable Energy from Salinity Gradients. Elsevier Science & Technology, 2016.
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Sustainable Energy from Salinity Gradients. Elsevier Science & Technology, 2016.
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Güereca, Leonor Patricia, Sergio Agustín Zamorano Guzmán, Rosario León-Lira, Guadalupe Paredes Figueroa, Adriana Rivera-Huerta, Dora Ruiz Méndez, Maribel García Sánchez y Itzel Rolón Rodríguez. Guide for the Development of Life Cycle Analysis of Ocean Energies. EPOMEX-UAC, 2021. http://dx.doi.org/10.26359/epomex.cemie082021.
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El incremento de la demanda energética a nivel mundial, en conjunto con el calentamiento global y la limitada disponibilidad de combustibles fósiles, han detonado el desarrollo tecnológico y la innovación en el sector energético a nivel mundial, buscando cada vez fuentes de energía más eficientes y con menores impactos ambientales. En este sentido, la energía del océano podría ser una fuente viable, ya que se ha estimado que la energía producida por las olas podría eventualmente proveer un porcentaje importante de la demanda eléctrica mundial actual. Una de las principales ventajas ambientales de la energía del océano es que la mayoría de los dispositivos diseñados a la fecha, no generan emisiones directas de Gases de Efecto Invernadero (gei). Sin embargo, es necesario evaluar de una forma integral los impactos ambientales acumulados por toda la cadena de valor, considerando desde la extracción de materias primas hasta la disposición final de los sistemas energéticos y tomando en cuenta todos los vectores involucrados: aire, agua y suelo. El enfoque de Análisis de Ciclo de Vida (acv), ha probado ser una metodología que apoya la evaluación ambiental de una forma holística. A la fecha, son contados los estudios de acv que se han realizado, por ello, el objetivo de esta Guía es compartir experiencias que apoyen el desarrollo de futuros estudios de Análisis de Ciclo de Vida de energías del océano. Lo anterior, permitirá que el desarrollo tecnológico para el aprovechamiento de dichas energías, evolucione de manera paralela con sus mejoras ambientales. Para cumplir el objetivo de la Guía, en la sección Análisis de Ciclo de Vida se presentan los fundamentos teóricos de la metodología, en donde se abordan los principales elementos que requieren la Normas iso 14040 e iso 14044 (iso, 2006) y se describen estudios de acv realizados a nivel mundial. Posteriormente, se presentan los principales elementos de los acv realizados en México a las energías del océano, abordando el acv de undimotriz, gradiente térmico, gradiente salino, corrientes y eólico marinos. El Capítulo 3 describe un conjunto de recomendaciones técnicas para el desarrollo de acv de energías del océano. Dichas recomendaciones se desprenden de los estudios realizados en México y buscan apoyar el cumplimiento de los principales requisitos de las Normas iso 14040 e iso 14044 (iso, 2006): Definición de objetivos y alcance, Inventario de Ciclo de Vida, Evaluación del Impacto de Ciclo de Vida e Interpretación. El Capítulo 4 aborda los potenciales impactos que no se consideran en los estudios de acv de energías del océano, como los impactos en la biodiversidad marina y los riesgos hidro-meteorológicos a los que están sujetos estos sistemas de energía. El Capítulo 5 plantea los marcos conceptuales en los que podría fundamentarse la evaluación de impactos sociales de las energías del océano. Finalmente, se presentan las conclusiones y se sugieren los futuros pasos en el camino hacia el desarrollo de energías del océano.
Capítulos de libros sobre el tema "Gradient salin"
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Herbst, David B. "Gradients of salinity stress, environmental stability and water chemistry as a templet for defining habitat types and physiological strategies in inland salt waters". En Saline Lakes, 209–19. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-017-2934-5_19.
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Castagna, S., S. Olivella, A. Lloret y E. E. Alonso. "Experimental and Numerical Investigation of Porosity Variations in Saline Media Induced by Temperature Gradients". En Computational Methods for Flow and Transport in Porous Media, 327–38. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-017-1114-2_22.
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Mead, Gregory A., David A. Hodell y Paul F. Ciesielski. "Late Eocene to Oligocene vertical oxygen isotopic gradients in the South Atlantic: Implications for warm saline deep water". En The Antarctic Paleoenvironment: A Perspective on Global Change: Part Two, 27–48. Washington, D. C.: American Geophysical Union, 1993. http://dx.doi.org/10.1029/ar060p0027.
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Naftalovich, Rotem y Daniel Denis. "Fluid Management in Neurosurgery". En Advanced Anesthesia Review, editado por Alaa Abd-Elsayed, 186—C71.S6. Oxford University PressNew York, 2023. http://dx.doi.org/10.1093/med/9780197584521.003.0071.
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Abstract Fluid movement within capillaries can be conceptualized by the oncotic gradient model as per the Starling law. The blood-brain barrier in the central nervous system begets the osmotic gradient as the primary driving force. The goal of fluid management during neurosurgery should be euvolemia to maintain cerebral perfusion pressure and intravascular volume using iso-osmolar crystalloids. Hypo-osmolar solutions should generally be avoided to prevent worsening cerebral edema. Hyperosmolar solutions such as mannitol and hypertonic saline can be used to preferentially draw free water from the interstitial space into the vasculature, decreasing cerebral edema and improving surgical exposure. Glucose-containing solutions should be avoided as hyperglycemia is associated with worse neurological outcomes. Prevention of vasospasm in subarachnoid hemorrhage can be managed medically with nimodipine and fluid management, with hemodynamic goals favoring perfusion. This can be achieved by the traditional “triple H” therapy of hypervolemia, hypertension, and hemodilution, but care must be taken to avoid hypervolemia-related side effects: pulmonary edema, myocardial ischemia (from increased afterload), and hyponatremia. Traumatic brain injury patients can present with significant hemodynamic instability, which further complicates their resuscitation.
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Boubakri, Ali, Salah Al-Tahar Bouguecha y Amor Hafiane. "Membrane distillation process: Fundamentals, applications, and challenges". En Solvents - Dilute, Dissolve, and Disperse [Working Title]. IntechOpen, 2024. http://dx.doi.org/10.5772/intechopen.1002375.
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Traditional thermal-based processes such as multistage flash and multi-effect distillation have been used for thousands of years to obtain freshwater from saline water. Recently, with the development of membrane-based technology, membrane distillation (MD) as a thermally driven membrane process has received significant attention. The driving force in MD is the vapor pressure gradient induced by temperature difference through hydrophobic microporous membrane pores. The membrane used for MD should be hydrophobic and microporous. In MD, the mechanism of transport involves simultaneously heat and mass transfers, which moves from the hot feed side to the cold permeate side. The performance of MD is evaluated based on various performance metrics including permeate flux, recovery ratio, thermal efficiency, gained output ratio, and specific thermal energy consumption. It has good ability for various industrial uses due to its moderate applied temperature and pressure, high rejection rate, less membrane fouling tendency and its ability to treat high-saline water. The water production cost still remains high compared to conventional processes. Therefore, MD can be cost-effectively when integrated with solar energy, geothermal energy and waste heat. Nevertheless, MD process requires focused research to improve its efficiency to become more mature and economically competitive at large scale.
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Hedenquist, Jeffrey W., Yukihiro Matsuhisa, Elji Izawa, Noel C. White, Werner F. Giggenbach y Masahiro Aoki. "Economic Geology and the Bulletin of the Society of Economic Geologists". En Epithermal Gold Mineralization and Modern Analogues, Kyushu, Japan, 97–126. Society of Economic Geologists, 2001. http://dx.doi.org/10.5382/gb.34.10.
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Abstract The Nansatsu district of southern Kyushu has been the site of calc-alkaline volcanism for the last 10 m.y., shifting eastward with time. Associated hydrothermal activity followed deposition of the volcanic host rocks by about 0.5 m.y. and was characterized by interaction of magmatic fluids with meteoric water under epithermal conditions, resulting in the formation of high sulfidation Cu-Au deposits at Kasuga, Iwato, and Akeshi. The orebodies consist of >95 wt percent SiO2 and result from leaching of the original andesite lava and pyroclastic flows by acid chloride-sulfate waters. These are inferred to have formed when magmatic vapors containing HCl and SO2 condensed into meteoric water. The residual silica (now quartz) orebodies are best developed where the host was initially permeable. The margins of the quartz bodies are abrupt, with narrow (1-2 m) halos representing the reaction front of acid waters isochemically dissolving the host rock. The halo comprises alunite (strongly zoned in Na and K, with P-rich cores), dickite, and/or kaolinite ± pyrophyllite, grading out into illite and interlayered illite-smectite clays, and finally, propylitic alteration. This pattern is characteristic of deposits of this type throughout the world, for example, at Summitville, Colorado, and Lepanto, Philippines. Mineralization occurred after initial leaching by the vapor condensates, with metals transported by a dense magmatic fluid. Mixing with meteoric water and the subsequent temperature decrease caused the general decrease in grade toward the margin of the quartz bodies; ore grades are restricted to the quartz bodies. Gold is most closely associated with enargite and pyrite; later minerals include covellite and then sulfur. The last stage of activity was steam-heated, with descending waters oxidizing sulfides to goethite and locally remobilizing Au into fractures (this varies in degree between deposits). Erosion exposed the orebodies to supergene weathering, continuing the sulfide oxidation and Au remobilization. Stable isotope results indicate that hypogene alunite formed from a mixture of magmatic fluid (δ18O = 7 ± 2‰, δD = −25 ± 5‰, similar to nearby active volcanic discharges) with local meteoric water. In contrast, the clays in the marginal halo have isotopic compositions indicating a δ18O shift of 6 to 8 per mil from local meteoric water values, probably due to water-rock interaction, and the δ18O values of residual silica quartz may also be due to meteoric water domination. Fluid inclusion study of postmineralization quartz crystals indicates that the fluids had a salinity of about 1 wt percent NaCl equiv during late quartz growth, though there is evidence in one sample for higher salinity fluid having been present, up to 30 wt percent NaCI equiv (some inclusions contain daughter minerals of halite and sulfur). The Th values of over 1,000 measurements on late quartz from the ore zones indicate that the mean temperature during that stage ranged from <200°C at Akeshi to about 200°C at Iwato and 230°C at Kasuga. The presence of vapor-rich inclusions, some with Thv similar to Thl, indicate the presence at times of a two-phase fluid in the center of the ore zones, with depths of about 150 to 300 m below the paleowater table. The mineralizing fluid was relatively oxidized (sulfide/ sulfate ratio about 3:1), close to pyrite-alunite coexistence. Under these redox conditions, a pH of 3 and over a temperature range of 200° to 300°C, AuCl2− complexing may dominate over HAu(SH)2 at salinities above about 2 wt percent NaCl. Several conditions are conducive for high sulfidation mineralization to occur: a crystallizing magma exsolves a fluid, with lower pressure conditions favoring metal fractionation from melt to fluid,the exsolved fluid separates into vapor and saline liquid phases due to immiscibility, with the latter being metal rich,the gas-rich (HCl and SO2 + H2S) vapor ascends to the surface, with at least a portion condensed into meteoric water, forming an acid fluid which leaches the host rock to create permeable zones for later mixing, andthe dense, metal-bearing fluid also ascends into this leached zone and precipitates Cu sulfosalts, sulfides, and Au upon mixing with meteoric water. If the saline liquid is not released from its source adjacent to the magma, due to lack of fracturing, or if there is a strong hydraulic gradient caused by high relief, only the vapor-related stage may occur. This will leave leached, barren rock which is characteristic of many eroded volcanic terranes.
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Fastie, Christopher L. y Robert A. Ott. "Successional Processes in the Alaskan Boreal Forest". En Alaska's Changing Boreal Forest. Oxford University Press, 2006. http://dx.doi.org/10.1093/oso/9780195154313.003.0012.
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Superimposed on the topographic and climatic gradients in vegetation described in Chapter 6 are mosaics of stands of different ages reflecting the interplay between disturbance and succession, that is, the ecosystem changes that follow disturbance. The nature of disturbance governs vegetation succession, and vegetation properties, in turn, influence disturbance regime. Both disturbance and succession are controlled by state factors and by stochastic variation in local conditions such as weather and the abundance of herbivores. Even in this relatively simple biome, the interactions among site, chance, and disturbance history result in a vast array of possible successional trajectories following a disturbance event, generating at least 30 forest types in interior Alaska (Viereck et al. 1992). Despite this broad range of possible dynamics, certain patterns recur more frequently than others (Drury 1956, Viereck 1970). In this chapter, we discuss selected successional pathways that commonly occur on river floodplains and on permafrost-free or permafrost-dominated upland sites in interior Alaska. River floodplains occupy only 17% of interior Alaska, but they account for 80% of the region’s commercial forests and therefore have attracted considerable attention from forest managers (Adams 1999). These forests provide an excellent example of primary succession, that is, the succession that occurs on surfaces that have not been previously vegetated. Although many successional pathways are possible on interior Alaska’s floodplains (Fig. 7.1; Drury 1956), the trajectory that actually occurs in a particular place is usually determined by the patterns of colonization during the first decades (Egler 1954). This, in turn, depends primarily on physical environment, flood events, and seed availability. For example, fine-textured sediments, which are common along the gradual grade of the Tanana River near Fairbanks (Chapter 3), retain more moisture than gravelly substrates and favor establishment of thinleaf alder (Alnus incana subsp. tenuifolia) following the initial colonization by willow (Salix). Alder is therefore a more important component of this successional sequence than along some other rivers. In this chapter, we focus on the alder-mediated pattern of floodplain succession, which has been the major focus of the LTER research program. The common and scientific names of species mentioned in this chapter are given in Table 6.1.
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"Balancing Fisheries Management and Water Uses for Impounded River Systems". En Balancing Fisheries Management and Water Uses for Impounded River Systems, editado por Tim Patton y Cris Lyday. American Fisheries Society, 2008. http://dx.doi.org/10.47886/9781934874066.ch11.
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<em>Abstract</em>.—While processes of depositional filling and ecological succession in natural lakes have been well described, these concepts are relatively new and seldom applied to reservoirs, especially at the landscape scale. However, ecological time has been sufficient to allow us to see successional processes in many reservoir systems. Illustrative of such processes, Lake Texoma is a 36,000-ha reservoir located in southern Oklahoma and northern Texas, and patterns of depositional filling and subsequent processes are apparent in the up-lake ends (there are two large-river tributaries) of this system. Completed in 1944, Lake Texoma has a drainage area of more than100,000 km2, most of which is highly erodable agricultural lands. We used historic aerial photographs, geographic information systems technology, and field measurements to examine a variety of surface and habitat features and analyzed experimental gill-net samples using ordination techniques to characterize the fish communities in portions of the reservoir most affected by sedimentation. Extensive sedimentation and accretion of sediments above water level has effectively resulted in surface area reduction, cove isolation, fragmentation of lacustrine habitats, morphometric changes, and establishment of terrestrial vegetation on newly deposited lands. Most notably, sedimentation has led to the development of linear bars of deposition above normal pool elevation that have blocked mouths of coves, bisected large areas of the reservoir, and fragmented several pools. In our study site alone, 332 ha (surface area) of reservoir has experienced accretion of land above the water level. Reservoir fragments had lower shoreline development values (mean = 2.21) than comparable control sites (mean = 3.39). Depositional shorelines associated with sedimentation exhibited lower gradients than nondepositional shorelines (mean = 2.0% versus 4.2%, respectively), and habitat heterogeneity was lower along depositional shorelines than along nondepositional shorelines. Fish communities in isolated reservoir fragments appeared to be distinct from fish communities in nonfragmented habitats. This change in community structure may be driven by an appreciable reduction of pelagic species from fragmented sites, as these sites have limited or no connectivity to the main body of the reservoir. With respect to the newly deposited lands, ecological succession of vegetation followed a progression from mud flats to dense, nearly monotypic stands of black willow Salix nigra forests within a few years. These habitat changes had strong implications to the fish communities as well as to adjacent terrestrial wildlife communities and will likely pose many challenges, and perhaps opportunities, for natural resource managers.
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Sai Sri Harsha, G., D. Chinna Babu, Vijeta Bhattacharya, Namrata Mishra, Neha Chopra y R. Jayasree. "(INJ. IRON SUCROSE) INDUCED ANAPHYLACTIC SHOCK – A DETAILED CASE REPORT". En Futuristic Trends in Pharmacy & Nursing Volume 3 Book 4, 18–23. Iterative International Publishers, Selfypage Developers Pvt Ltd, 2024. http://dx.doi.org/10.58532/v3bipn4p1ch2.
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Background: Anemia is the leading cause of disability worldwide, and many groups of patients need iron supplementation (e.g. patients with renal failure, those with inflammatory bowel disease, and pregnant women among others). Intravenous iron administration is an effective method of treating iron deficiency anemia, but there have been concerns about adverse side effects, particularly serious events such as anaphylactic reactions. Anaphylaxis is a serious life-threatening and systemic allergic or hypersensitivity reaction with immediate onset. Management of anaphylaxis in pregnancy is similar to that in nonpregnant women. The recommendations for the management of acute anaphylactic episodes include immediate cessation of the triggering factors, airway and BP support, prevention of hypoxia with 100% oxygen, aggressive fluid resuscitation with normal saline, and various medications, such as epinephrine, antihistamines, and corticosteroids. Case Presentation: A 21-year-old female patient G3P2L2 with 8MA with anemia. Given Anaemia (Hb:8g/dl) patient went to a local hospital and Inj. Iron Sucrose was given. After 2 hours of Injection patient developed Angioedema, Headache, Vomiting, and Giddiness. After basic supportive management, she was sent to a district hospital where supportive management was given. Given worsening of blood pressure she was brought to SVIMS for further evaluation and management. The patient presented to the Emergency Medicine department with complaints of facial (lip) swelling, neck swelling, shortness of breath-grade II-III NYHA, and profuse sweating. On general examination, her BP was found to be decreased i.e. 90/50 mm of hg and her pulse rate was 110 beats per minute. Laboratory Examinations revealed decreased levels of Hb, RBC, PCV, MCV, MCH, Lymphocytes, and Serum potassium. Her WBC, ESR, and Neutrophil count were found to be increased. The patient was diagnosed with Iron Sucrose (Inj.) induced Anaphylactic Shock. Inj.HYDROCORTISONE-100mg-IV-STAT, Inj.AVIL-25mg-IV-STAT, Inj. EMESET-4mg-IV-STAT, Inj.PANTOP-40mg-IV-STAT was given to treat the patient. Conclusion: Our findings suggested that Hypersensitivity reactions to IV iron are rare but potentially life-threatening. They are at least partly preventable by the implementation of risk minimization measures. Their management requires prompt recognition and grading of severity, together with meticulous monitoring and immediate treatment.
Actas de conferencias sobre el tema "Gradient salin"
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Riza, Lala Septem, Muhammad Aziz Ashari y Rani Megasari. "The Implementation of Gradient Descent Based Methods Using Parallel Computing in R for Regression Tasks". En 2018 International Symposium on Advanced Intelligent Informatics (SAIN). IEEE, 2018. http://dx.doi.org/10.1109/sain.2018.8673361.
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Emdadi, Arash, Yunus Emami, Mansour Zenouzi, Amir Lak, Behzad Panahirad, Aydin Lotfi, Farshad Lak y Gregory J. Kowalski. "Potential of Electricity Generation by the Salinity Gradient Energy Conversion Technologies in the System of Urmia Lake-Gadar Chay River". En ASME 2014 8th International Conference on Energy Sustainability collocated with the ASME 2014 12th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/es2014-6310.
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Energy production from salinity gradients is one of the developing renewable energy sources, and has significant potential for satisfying electrical demands. Urmia Lake is the second hyper-saline lake in the world and there is a significant salinity gradient between the lake’s water and the waters of those rivers that flow into the lake. A methodology for determining the feasibility for electrical production using Salinity Gradient Power (SGP) is developed for two different types of systems using this location as an example. Reverse Electrodialysis (RED) and Pressure Retarded Osmosis (PRO), The Gadar Chay River is one of thirteen rivers that run into Urmia Lake; it supports about 10% of the lake’s water. In this study, important parameters such as river discharge and the salinity content of river and lake’s waters for several years were investigated. The theoretical and technical potential of salinity gradient energy was also determined. These calculations indicate that 206.08 MW of electrical power could be produced at this location when the river flow is approximately 29.82 m3/s and they illustrates the potential for salinity gradient energy extraction between Urmia Lake and The Gadar Chay River.
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Ballesteros Rozo, L. T. "Energetic Potential of the Saline Gradient in the Bay of Cartagena in the Colombian Caribbean". En First EAGE Online Workshop on Water Footprint. European Association of Geoscientists & Engineers, 2023. http://dx.doi.org/10.3997/2214-4609.202383001.
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Ding, Lei, AbdulKareem M. AlSofi, Muhammad M. AlMajid y Pramod Patil. "CO2 Soluble Surfactants Assisted Carbon Storage Under Achievable Pressure Gradients: Effect of Surfactant Partitioning Behavior During Continuous CO2 Injection". En International Petroleum Technology Conference. IPTC, 2024. http://dx.doi.org/10.2523/iptc-23958-ms.
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Abstract Injecting CO2 into the saline aquifers normally suffers from low sweep efficiency due to the smaller density and viscosity of CO2 compared to brine. The potential of CO2 soluble surfactants assisted carbon storage in carbonate formations was first evaluated by core flooding tests (at 65°C, 150 bar & 90,000 TDS) in Indiana Limestone at different gas fractions, where the surfactants were injected with the CO2 phase (CCI+S). The pressure gradients and CO2 saturation were continuously monitored during the coreflooding tests. It was found that foam was generated during CCI+S when 0.07 wt.% of surfactant was injected with CO2. Moreover, the CO2 saturation at steady states can be significantly enhanced in the presence of foam from experimental observations. The CO2 saturation reached 60% (compared to 32% without surfactant) after 1.5 PV of CCI+S. The maximum pressure gradient was approximately 1.5 psi/ft in 162 mD Indiana Limestone at a Darcy velocity of 1.0 ft./d, which is technically feasible for field applications. Furthermore, an improved foam model incorporating the surfactant partitioning behavior was developed to obtain the foam modeling parameters by history matching the steady-state foam behavior. The effect of surfactant partition on CO2 transport behavior was studied by a 1D synthetic model at a lab scale and 2D synthetic homogeneous/heterogeneous models at the field scale, using modeling parameters and surfactant concentrations that are realistic for field tests. The sensitivity analyses imply that the CO2 storage efficiency largely depends on surfactant partitioning behavior (Ksgw), dispersivity, and formation heterogeneity, etc. The simulation results also indicate that there may always exist an optimal Ksgw for CCI+S, which satisfies both good CO2 sweep efficiency and acceptable injectivity. The advantages of injecting the surfactant with CO2 are more evident in heterogeneous saline aquifers, indicating an enormous potential of CCI+S for carbon storage. The novel injection strategy provides a promising solution for carbon sequestration in saline aquifers.
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Saundry, R. H., P. Kopp y G. F. Savidge. "THE INTERACTION OF THE FACTOR VIII/vWF COMPLEX WITH IMMOBILISED METAL AFFINITY CHROMATOGRAPHY (IMAC) MATRICES". En XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644046.
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1MAC principles were used to investigate the binding of Factor VIII/vWF from either Al(OH)3 - absorbed citrated PPP or cryoprecipitate using citrate-saline buffers. Factor VIII/ vWF showed high affinity for both Zn2+ - or Cu2+ - immobilised on biscarboxymethylaminoSepharose 4B at ambient room temperature, but no interaction with Ca2+, Mg2+, Mn2+ or Cd2+ - immobilised matrices.Factor VIII/vWF could be re-eluted as a single component from Zn2+ - columns using either decreasing pK, or increasing competitor ligandconcentrations. In pK gradients comprising 14mM citrate, 2.14mM CaCl2, 0.15m NaCl Factor VIII eluted at pH 6.50, whereas in pH gradients comprising 0.1m Tris, 2.5mM CaCl2 pH 7.5 and 0.1M succinate, 2.5mM CaCl2 pH 5.5 Factor VIII eluted at pH 6.06. Citrate behaves as a competitor ligand; at 4° in citrate buffer Factor VIII did not bind.In citrate-saline buffers pH 7.2 Factor VIII could be reeluted in high yield (100% Factor VIII:Ag; 70% VIII:C; 90% vWF:Ag) through application of linear competitor ligand gradients (at 11.5mM imidazole, 15.4mM dl-Eistidine, 45mM L-Lysine, or 1.7% BSA) , whereas 1.0M NaCl or 1.0M NH4Cl were ineffective. The Factor VIII activities co-eluted ahead of, but incompletely resolved from the re-eluted Fg and Fn. If 5 mg/ml. BSA was incorporated into the buffers Factor VIII was quantitatively recovered in the column wash - through fractions leaving all the Fg and Fn bound to the matrix.
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Penny, G. S., S. M. Bhagwat, C. E. Shuchart y V. P. Gupta. "Improving Injectivity of CO2 in Saline Aquifers Through Chemical Additives". En SPE Annual Technical Conference and Exhibition. SPE, 2024. http://dx.doi.org/10.2118/220743-ms.
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Summary A key metric for Carbon Capture and Storage (CCS) projects is the rate of injection of supercritical CO2 (sCO2) into the subsurface and maximizing injectivity will be important for success. The sCO2 injection rate into saline aquifers is limited by formation permeability and residual water saturation held in place by capillary pressure. The objective of this work is to explore the application of additives to lower the capillary pressure and the water saturation in the near wellbore region and thereby increase the relative permeability to sCO2. The intended benefit will be the ability to inject CO2 at higher rates while maintaining injection pressure below the desired level/fracture gradient or injecting at reduced pressures for the same rate. Screening tests identified several types of additives (Nonionic/Cationic/Anionic/Amphoteric) that reduced brine-CO2 IFT by a factor of 10 from 20-40 mN/m to 2-4 mN/m at 1000-2000 psi and modified contact angle between CO2, brine and sandstone and dolomite cores from 20-25 degrees with 2% KCl alone to 30-40 degrees with additives at 1000 to 2000 psi. In brine displacement tests in 100 md cores, the best additives when used in a concentration range of 0.1% to 0.2% decreased the water saturation by 10-30% and reduced the displacement pressures by ∼50% over the control, resulting in proportional increase of the relative permeability to sCO2. Well model results show that doubling the relative permeability in the near wellbore region can increase the CO2 injectivity by ∼20%. Recommendations on treatment volumes and procedures for candidate injection wells are provided. The approach presented here can provide a low-cost option to increase injectivity and other benefits including compensating for injection well downtime, providing higher injection rates in lower permeability rocks, and reducing injection pressures for safer and more cost-efficient operations.
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Tom, Imaobong, Quang M. Nguyen y Mustafa Onur. "Performance Comparison of Gradient-Free Optimization Methods for Well Placement and Well Controls Optimization for Geologic CO2 Storage". En SPE Europe Energy Conference and Exhibition. SPE, 2024. http://dx.doi.org/10.2118/220026-ms.
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Abstract Population-based (gradient-free) methods have become attractive for solving optimization problems since they have been known to locate "optimal" (best) positions within a search space. In this study, we investigate the use of three different gradient-free optimization methods namely: Iterative Latin Hypercube Sampling (ILHS), Particle Swarm Optimization (PSO), and Genetic Algorithm (GA) for well placement and well controls optimization problem of the CO2 underground storage in a 2D saline aquifer with bound constraints on the design variables. We also consider sequential optimization of well locations and well controls using the gradient-free methods. To evaluate the performance of these algorithms, we test the methods on well-known test (or toy) problems such as the multi-dimensional (40 design variables) Rosenbrock function, as well as the Traveling Salesman Problem (TSP) with 20 cities (20 design variables). We further extend the study to a more complex problem which involves finding the optimal well types, well locations, or well controls for a CO2 injection problem in a synthetic saline aquifer compositional model built in a commercial simulator. The objective function formulated for the CO2 injection problem is the net present environmental value (NPEV) involving discrete design variables (well types and well locations) and real design variables (well controls). Results obtained from the performance comparison of these gradient-free methods on the toy problems demonstrate the superior performance of the ILHS over PSO and GA for the Rosenbrock test function, while GA outperforms ILHS and PSO in solving the TSP. We also observe that for the simple well locations optimization problems involving one or two wells, all three algorithms obtained comparable results, given the same number of samples and number of iterations. However, for more complex cases such as the sequential or simultaneous optimization problems, when multiple wells which may include injectors and producers are present, we observe significant differences in the selection of the optimal well types and well locations among the three optimizers. In the simultaneous optimization of well types, well locations, and well controls, when both injectors and producers are BHP controlled, the results obtained showed that it is more optimal for at least one producer to be present, and for the injectors to be operated at the upper bound of the injector BHP, while the producers operated at the lower bound of the producer BHP to maximize the NPEV.
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Wijaya, Nur, Derek Vikara, David Morgan, Timothy Grant y Donald Remson. "Basin Management of Geologic CO2 Storage: Effect of Well Spacing on CO2 Plume and Pressure Interference". En SPE Western Regional Meeting. SPE, 2022. http://dx.doi.org/10.2118/209283-ms.
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Abstract Large-scale deployment of carbon capture and storage (CCS) is a key decarbonization approach to achieve drastic reductions in greenhouse gas emission levels. The United States Department of Energy's National Energy Technology Laboratory, through the Carbon Storage Assurance Facility Enterprise Initiative projects, defines a commercial-scale CO2 saline storage project as one in which at least 50 million tonnes of CO2 are injected over the course of 20 to 30 years. Large-scale decarbonization through CCS may likely involve many commercial-scale CO2 storage projects located in close proximity. Nearby injection operations may result in CO2 plume commingling and create pressure buildup over time, which could cause pressure interference and may require preventative strategies to avoid exceedance of fracture pressure threshold. This study employs numerical modeling to analyze the evolution of the extent of CO2 and pressure plumes in which the commercial-scale CO2 storage projects inject simultaneously into a common storage formation from multiple projects located in proximity. Injection operations target an extensive saline formation with formation top of 1 km below ground surface, thickness of 200 m, horizontal and vertical permeabilities of 50 and 15 mD, porosity of 10%, and all external boundaries closed to fluid flow (i.e., top, bottom and all sides). The injection occurs at 1 million tonnes/year per well for 30 years, followed by a 50-year post-injection period (PISC). The effect of well spacing and resulting pressure buildup and CO2 plume migration is explicitly evaluated. For the circumstances modeled, our analysis indicates that the radius of the CO2 plume extends 2-4 km from the CO2 injection well(s). Under the multi-project injections, CO2 plume commingling does not occur during injection; however, during PISC and pressure equilibration, CO2 plumes commingle under certain well spacings. However, the radius of the pressure-buildup plume is in the range of tens or a few hundreds of kilometers, depending on the amount of pressure increase used to define the plume edge. These findings indicate that a degree of pressure interference can occur between storage projects located near each other, particularly during the early stages of the project. Additionally, our analysis of pressure interference shows that required well spacing needed to avoid approaching or exceeding fracture pressure thresholds can be extensive for formations with low fracture gradients (i.e., in the range of 80–125 km for formations with a pressure gradient of 0.6 psi/ft), but significantly smaller for formations with higher fracture gradients (i.e., 5 km for 0.8 psi/ft). Given the potential pressure interference which may occur from multiple projects, this analysis shows the importance of coordination among storage operators and regulatory stakeholders. Because this study analyzes a very specific geologic situation, well configuration, CO2 injection rate and boundary conditions, this exploratory study bears further investigations across other geologic situations.
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Abd El-Aziz, Khalid M., Karim Hamza, Mohamed El Morsi, Ashraf O. Nassef, Sayed M. Metwalli y Kazuhiro Saitou. "Optimum Solar HDH Desalination for Semi-Isolated Communities Using HGP and GA’s". En ASME 2014 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/detc2014-34598.
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Modeling and unit-cost optimization of a water-heated humidification-dehumidification (HDH) desalination system were presented in previous work of the authors. The system controlled the saline water flow rate to prevent salts from precipitating at higher water temperatures. It was then realized that this scheme had a negative impact on condensation performance when the controlled flow rate was not sufficiently high. This work builds on the previous system by disconnecting the condenser from the saline water cycle and by introducing a solar air heater to further augment the humidification performance. In addition, improved models for the condenser and the humidifier were used to obtain more accurate productivity estimations. The Heuristic Gradient Projection (HGP) optimization procedure was also refactored to result in reduced number of function evaluations to reach the global optimum compared to Genetic Algorithms (GA’s). A case study which assumes a desalination plant on the Red Sea near the city of Hurghada is presented. The unit-cost of produced fresh water for the new optimum system is $0.5/m3 compared to $5.9/m3 for the HDH system from previous work and less than the reported minimum cost of reverse osmoses systems.
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Pisarski, Pawel, Ilia Chaikine, Alexey Romanov, Richard Holst y Richard Hares. "De-Risking of Early-Stage Saline Aquifer CO2 Sequestration Projects Using a Data-Driven Approach". En SPE Canadian Energy Technology Conference and Exhibition. SPE, 2023. http://dx.doi.org/10.2118/212804-ms.
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Abstract Early-stage saline aquifer CO2 sequestration projects are filled with uncertainty and often pose a challenge for decision makers. The industry-standard saline aquifer suitability screening checklists provide limited insight into sequestration opportunity high-grading and development planning. Detailed full-field geological and numerical simulation modelling can be prohibitively expensive in the initial project scoping stage. Here we present an alternative data-driven approach to assist in early-stage CO2 sequestration project scoping. A developed machine learning model ties geological variables (predictors) with CO2 sequestration key variables (responses), such as cumulative CO2 injected, number of injection wells, injection rate, and CO2 plume diameter. The dataset underpinning the model consists of over 200 numerical simulation sensitivity runs. The Bayesian regression approach has been utilized allowing to express the model parameters with probability distributions. The novel machine learning model predicts key project variables, advancing the understanding of future saline aquifer development plans. The estimates are expressed as probability distributions, which allow for an uncertainty assessment that is tied to critical project decision-making variables. These results can be further used to determine the impact of geological variables on project key variables. The demonstrated novel application of Bayesian regression allows to assess uncertainty of project key variables and can be used to reduce the risk of CO2 sequestration projects prior to project decision-making. The solution provides the basis for economic modelling and accelerates the understanding of future saline aquifer development plans and the impact of key uncertainties.