Segui questo link per vedere altri tipi di pubblicazioni sul tema: Seawater.
Tesi sul tema "Seawater"
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Vedi i top-50 saggi (tesi di laurea o di dottorato) per l'attività di ricerca sul tema "Seawater".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Vedi le tesi di molte aree scientifiche e compila una bibliografia corretta.
1
Nayar, Kishor Govind. "Improving seawater desalination and seawater desalination brine management". Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/121886.
Testo completoAbstract (sommario):
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019Cataloged from PDF version of thesis. "Thesis contains very faint/illegible footnote numbering"--Disclainer Notice page.
Includes bibliographical references.
Water scarcity is an increasing problem globally. Seawater desalination is increasingly being relied upon as a means of mitigating the problem of water scarcity. However, seawater desalination has costs associated with it: capital costs, cost of energy to desalinate and environmental costs from the discharge of high salinity brine. Efficient and cost-effective seawater desalination and desalination brine management systems are necessary to make seawater desalination a sustainable scalable process. This work seeks to improve seawater desalination and seawater desalination brine management in several ways. For the first time, the thermophysical properties of seawater have been characterized as a function of pressure across the full desalination operating regimes of temperature, salinity and pressure. Functions that allow accurate thermodynamic least work of desalination and seawater flow exergy analysis have been developed.
The least work of desalination, brine concentration and salt production was investigated and the performance of state-of-the-art brine concentrators and crystallizers was calculated. Hybrid designs of reverse osmosis (RO) and electrodialysis (ED) were proposed to be integrated with a crystallizer to concentrate desalination brine more efficiently. The RO-ED-crystallizer concept was applied to two separate applications: (a) salt production from seawater and (b) zero brine discharge seawater desalination. A parametric analysis to minimize the specific cost of salt production and water production was conducted. Parameters varied were: the ratio of seawater to RO brine in the ED diluate channel, ED current density, ED diluate outlet salinity, electricity, water and salt prices, and RO recovery by adding a high pressure RO (HPRO) stage. Results showed that significant cost reductions could be achieved in RO-ED systems by increasing the ED current density from 300 A/m² to 600 A/m².
Increasing RO brine salinity by using HPRO and operating at 120 bar pressure reduced salt production costs while increasing water production costs. Transport properties of monovalent selective ED (MSED) membranes were also experimentally obtained for sodium chloride, significantly improving the accuracy of modeling MSED brine concentration systems. MSED cell pairs transported only about ~~50% the water but nearly as much salt as a standard ED cell pair, while having twice the average membrane resistance.
Supported by Center for Clean Water and Clean Energy at MIT and KFUPM Project No. R13-CW-10, King Fahd University of Petroleoum and Minerals (KFUPM), Dhahran, Saudi Arabia
by Kishor Govind Nayar.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Mechanical Engineering
2
Yu, Kwun Lok. "Modeling injection and extraction wells for seawater desalination in SEAWAT". Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111534.
Testo completoAbstract (sommario):
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 67-68).
Subsurface intakes and disposal systems are gaining interest for seawater desalination in comparison with the older open ocean intake/discharge systems that induce many environmental problems. Facilities using reverse-osmosis technology to desalinate seawater require stringent feed water quality to operate efficiently, and are particularly prone to membrane fouling when contaminants enter the system. Subsurface systems leverage coastal aquifers as natural filters, increasing the effective flow field for seawater extraction and brine disposal, and are proven to reduce impacts on the coastal environment. In this study, we developed groundwater models in SEAWAT, a three-dimensional finite difference groundwater model capable of simulating a varying-density environment, to learn about the interactions of seawater, brackish water, freshwater and brine due to extraction and injection activities, with salinities ranging from 0-70 PSU, and densities ranging from 10009/L to 10509/L. Two hypothetical desalination plants with freshwater production rates adequate to supply 750 people and 7500 people were simulated. Using simplified cross-sectional two-dimensional models, an optimal offshore location can be identified to implement subsurface intake systems to extract seawater closest to the coastline while minimizing impacts on existing freshwater storage from seawater intrusion. Models have also shown that for the same desalination plants, the coastal aquifer is more tolerant of brine injection than feedwater extraction; given that desalination plants typically have a 50% efficiency, half of the extracted seawater becomes freshwater, and only the remaining wasted brine is injected into the aquifer. A 2D test model with an expanded longshore domain, as well as a 3D test model with non-uniform properties in the longshore direction were also developed to test sensitivity when the longshore domain is changed.
by Kwun Lok Yu.
M. Eng.
3
Errani, Edoardo. ""In silico" seawater". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/18101/.
Testo completoAbstract (sommario):
Con In silico seawater si intende il calcolo di alcune proprietà chimico fisiche dell’acqua marina attraverso simulazioni al calcolatore. L’acqua marina è essenzialmente una soluzione elettrolitica caratterizzata da una composizione molto complessa, ci sono voluti più di 100 anni di studio. Data l’enorme complessità di tale soluzione è facile rendersi conto che il numero di molecole necessarie per la riproduzione della composizione dell’acqua marina è estremamente grande per essere implementato in simulazioni molecolari. In questo lavoro viene descritto un modello semplificato di acqua marina adottato per una simulazione
numerica. In prima approssimazione, sono stati trascurati gli ioni a bassa concentrazione, come, ad esempio,
HCO3− (XHCO3−≈0.0015). Gli ioni considerati sono Na+, Cl−, Mg2+, SO42−, Ca2+ e K+. Uno degli scopi principali di questo lavoro è quello di indagare il contributo dei diversi ioni sulle proprietà dell’acqua marina. Seguendo questa linea di ragionamento è stato interessante analizzare la sostituzione degli ioni Ca2+ e K+ con Mg2+ e Na+, rispettivamente.
Le proprietà dell’acqua marina sono quindi state confrontate con quelle di una soluzione di NaCl, che rappresenta il soluto maggioritario. In questo lavoro di tesi sono stati usati due diversi Force Field (FF): il Joung-Cheatham (JC) e l’OPLS (Optimized Potentials for Liquid Simulations). Abbiamo dimostrato che entrambi i potenziali danno un risultato soddisfacente nel riprodurre le proprietà termodinamiche e dinamiche dell’acqua marina. Nel caso della viscosità e della densità, i dati calcolati sono comparati con dati sperimentali. Mentre per quanto riguarda la struttura e i coefficienti di diffusione, per i quali non vi è alcun dato sperimentale per l’acqua marina, sono comparati tra di loro i dati calcolati con i diversi modelli. E` stato quindi sviluppato un primo modello soddisfacente di acqua marina, ma per realizzare un Force Field più accurato sono ancora necessari notevoli sforzi.
4
Hatton, Angela. "Dimethylsulphoxide in seawater". Thesis, University of East Anglia, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296563.
Testo completo
5
Powell, Matthew Jacob. "Seawater proteomics the recovery, separation, and characterization of dissolved proteins in seawater /". Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3945.
Testo completo
6
Prieto, Carmen. "Groundwater-Seawater Interactions : Seawater Intrusion, Submarine Groundwater Discharge and Temporal Variability and Randomness Effects". Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-222.
Testo completo
7
Rust, Arlene Elizabeth. "Thermohaline convection in polar seawater". Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321658.
Testo completo
8
Spokes, Lucinda Jane. "Photochemical redox reactions in seawater". Thesis, University of East Anglia, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294086.
Testo completo
9
Mass, John Thomas. "Dynamic properties of seawater surfactants". Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38179.
Testo completo
10
Ülpre, H. "Turbulent acidic discharges into seawater". Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1467269/.
Testo completoAbstract (sommario):
This thesis analyses the chemistry and physics behind acidic jets and plumes. The research was motivated from the discussions between industry and regulatory bodies concerning the dispersion of highly acidic discharges from exhaust gas scrubbers on ships into seawater. The industrial problem is simplified in an analytical model for acidic jets and plumes, which is then validated through an experimental study. The analytical model allows for the construction of an optimisation tool that considers the acidity of the discharge, the alkalinity of local seawater and the required scrubber flow rate to propose optimal discharge pipe configurations. This tool can be used for designing discharge pipe configurations in compliance with regulation MEPC 59/24/Add.1 Annex 9. The analytical model was then extended to also take into account the effects of ambient flow and buoyancy on the discharge trajectory. Existing regulatory compliance tests for scrubber discharges assume that no deflection occurs, however, the experimental study shows that an offset of one jet radius leads to an overestimation of pH recovery by one unit. Simplified expressions are developed to improve the accuracy of regulatory compliance tests by taking into account the effects of buoyancy and ambient flow. A general purpose computational fluid dynamics code was written to study the dispersion of contaminants in the wake of a ship. The study suggests that rapid dilution occurs in the near field as a result of the turbulence generated by propulsion, and further dilution occurs more slowly through the widening of the ship wake. Different velocity profiles are generated when the ship is either decelerating, accelerating or moving at a steady pace, but the widening of the wake is relatively insensitive to these factors in the near field.
11
Lourens, Christo Le Roux. "Seawater distillation through solar evaporation". Thesis, Cape Peninsula University of Technology, 2007. http://hdl.handle.net/20.500.11838/1272.
Testo completoAbstract (sommario):
Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, Cape Town, 2007An investigation was performed into a new desalination plant operating on the principles of distillation through the utilisation of solar energy only. The need for such a system is due to the high energy requirements of current large scale desalination systems and that, in the future, more and more desalinated water will be required to sustain life in certain areas. A conceptual design of such a plant was completed and it proved its feasibility by providing an in depth explanation of the principles that govern its operation. A computer model, in the form of a MathCAD program, was developed to simulating this process flow. The accuracy of the program was investigated with the help of a pilot plant. It is shown that such a full scale plant would produce, in the region of Saldanha Bay, a town on the Western Coast of South Africa, 5000m3 ofpotable water a day with a solar absorption/evaporation area of 1,87knlrequiring only 1,75kWh per cubic meter of water produced. Its electrical energy requirements can be provided using solar panels allowing the plant to remain independent of external electrical supplies. This electrical energy requirement is less than 33% of the least energy intensive alternative method, reverse osmosis. Since the production rate is dependent on the absorption/evaporation area the plant can be scaled to fit the specific production rate required.
12
Abarca, Cameo Elena. "Seawater intrusion in complex geological environments". Doctoral thesis, Universitat Politècnica de Catalunya, 2006. http://hdl.handle.net/10803/6243.
Testo completoAbstract (sommario):
Modelling seawater intrusion (SWI) has evolved from a tool for understanding to a water management need. Yet, it remains a challenge. Difficulties arise from the assessment of dispersion coefficients and the complexity of natural systems that results in complicated aquifer geometries and heterogeneity in the hydraulic parameters. Addressing such difficulties is the objective of this thesis. Specifically, factors that may affect the flow and transport in coastal aquifers and produce heterogeneous salinity distributions are studied.First, a new paradigm for seawater intrusion is proposed since the current paradigm (the Henry problem) fails to properly reproduce observed SWI wedges. Mixing is represented by means of a velocity dependent dispersion tensor in the new proposed problem. Thereby, we denote it as "dispersive Henry problem". SWI is characterized in terms of the wedge penetration, width of the mixing zone and influx of seawater. We find that the width of the mixing zone depends basically on dispersion, with longitudinal and transverse dispersion controlling different parts of the mixing zone but displaying similar overall effects. The wedge penetration is mainly controlled by the horizontal permeability and by the geometric mean of the dispersivities. Transverse dispersivity and the geometric mean of the hydraulic conductivity are the leading parameters controlling the amount of salt that enters the aquifer.
Second, the effect of heterogeneity was studied by incorporating heterogeneity in the hydraulic permeability into the modified Henry problem. Results show that heterogeneity causes the toe to recede while increases both the width and slope of the mixing zone. The shape of the interface and the saltwater flux depends on the distribution of the permeability in each realization. However, the toe penetration and the width of the mixing zone do not show large fluctuations. Both variables are satisfactorily reproduced, in cases of moderate heterogeneity, by homogeneous media with equivalent permeability and either local or effective dispersivities.
Third, the effect of aquifer geometry in horizontally large confined aquifers was analyzed. Lateral slope turned out to be a critical factor. Lateral slopes in the seaside boundary of more than 3% cause the development of horizontal convection cells. The deepest zones act as preferential zones for seawater to enter the aquifer and preferential discharging zones are developed in the upwards lateral margins. A dimensionless number, Nby, has been defined to estimate the relative importance of this effect.
All these factors can be determinant to explain the evolution of salinity in aquifers such as the Main aquifer of the Llobregat delta. Finally, a management model of this aquifer is developed to optimally design corrective measures to restore the water quality of the aquifer. The application of two different optimization methodologies, a linear and a non-linear optimization method, allowed (1) to quantify the hydraulic efficiency of two potential corrective measures: two recharge ponds and a seawater intrusion barrier; (2) to determine the water necessary to be injected in each of these measures to restore the water quality of the aquifer while minimizing changes in the pumping regime and (3) to assess the sustainable pumping regime (with and without the implementation of additional measures) once the water quality has been restored. Shadow prices obtained from linear programming become a valuable tool to quantify the hydraulic efficiency of potential corrective measures to restore water quality in the aquifer.
13
Nightingale, Philip D. "Low molecular weight halocarbons in seawater". Thesis, University of East Anglia, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280971.
Testo completo
14
Gates, Ruth D. "Seawater temperature and algal-cnidarian symbiosis". Thesis, University of Newcastle Upon Tyne, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.346445.
Testo completo
15
Speyer, Andrew James. "Wear/corrosion sensing in flowing seawater". Thesis, University of Southampton, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269992.
Testo completo
16
Woodhouse, Oliver Brian. "Osmium in seawater : analysis and geochemistry". Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284676.
Testo completo
17
Sargeant, Stephanie L. "Microbial utilisation of methanol in seawater". Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/60569/.
Testo completoAbstract (sommario):
Methylotrophs are aerobic bacteria that use methanol as a carbon and/or energy source. They are widespread but have not been extensively studied in marine environments. Seawater 14C tracer studies were combined with molecular biological cultivation- independent techniques (polymerase chain reactions using 16S rRNA and mxaF gene specific primers, 454 pyrosequencing) to investigate temporal and spatial variability in rates of microbial methanol utilisation and methylotrophic community composition in temperate coastal waters of the western English Channel, UK (WEC) and the Atlantic Ocean (Atlantic Meridional Transect 19). Microbial methanol dissimilation rates were, on average, thirteen times higher in waters of the WEC (0.65–11.2 nmol l-1h-1) than in open ocean waters of the Atlantic (0.01–1.7 nmol l-1h-1), with maximum rates found during winter months in the WEC. Highest methanol dissimilation rates in the Atlantic were measured in the north subtropical gyre of up to eight times higher than other Atlantic regions. Microbial methanol assimilation rates in the Atlantic Ocean (0.01–2.2 x10-2 nmol l-1h-1) were up to four times higher than those from the WEC (0.04–2.6 x10-2 nmol l-1h-1). Methanol assimilation rates from the WEC displayed seasonal maxima during summer, but showed methanol bacterial growth efficiency (BGEM) of <1% all year. Overall, assimilation rates were highest in the equatorial upwelling where BGEM reached 17%. Methanol assimilation rates showed a significant positive correlation with bacterial leucine incorporation in contrast to methanol dissimilation, which showed a negative relationship. Methanol dissimilation rates strongly correlated with the abundance of bacteria of the SAR11 clade, previously shown to utilise methanol as an energy source. The first basin scale approach using 454 pyrosequencing in the Atlantic revealed a remarkable increase in bacterial diversity in the nutrient limited southern gyre. Use of mxaF PCR primers also confirmed the ubiquitous presence of methylotrophic bacteria throughout the top 200m of the Atlantic Ocean.
18
Batho, Mark P. (Mark Peter) 1968. "Economics of seawater desalination in Cyprus". Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/67163.
Testo completoAbstract (sommario):
Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999.Includes bibliographical references (p. 48-52).
The Republic of Cyprus is currently suffering from severe drought conditions. This is not uncommon to Cyprus, as they frequently experience three to four year droughts every decade. They are currently in the middle of their fourth year of drought. Some Cypriots believe that the main reason for water shortages is due only to low levels of rainfall (average rainfall in Cyprus is 500 mm per year, and less than 400 mm per year is considered a drought year). It is not disputed that this is part of the problem. However, my belief, along with many Cypriots is that the biggest part of the problem is one of water allocation. Agriculture in Cyprus contributes approximately 5% to the GDP, yet consumes 75% of available water in Cyprus. The remainder of water is left for the sector of the economy that produces the remaining 95% of the GDP, of which municipal, industrial and tourist uses are of greatest importance. One may ask why this is so. According to some Cypriots, it is because Cypriot farmers are thought to be a politically influential group, and that they farm more as a way of life, rather than to earn a living directly. Others discount this "way of life" theory. What is important, however is that farming is using a lot of water and is contributing very little to the GDP of Cyprus. For example, Citrus crops grown within the Southern Conveyor System (a large network of water conveyance pipes stretching for over 100 km in the southern part of the island) (see Figure 3, page 16) uses approximately 21% of all available water available in Cyprus, and without Government subsidies would not show profitability. Although there may be some aesthetic value in citrus groves one must ask if it is economically and environmentally justified to continue farming citrus. To do so means building seawater desalination plants that contribute 5.0 to 6.0 kg of CO 2, a greenhouse gas, to the atmosphere per m3 of water produced by desalination, along with the cost of the water nearing one US dollar per m3 . Desalination is a painful solution to Cyprus' water shortage that could be otherwise be addressed with a proper water allocation scheme.
by Mark P. Batho.
M.Eng.
19
McCarthy, Matthew Duffield. "Major biochemical composition of dissolved high molecular weight organic matter in seawater /". Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/11009.
Testo completo
20
Hughes, Amanda Jane. "Solar powered membrane distillation for seawater desalination". Thesis, Heriot-Watt University, 2015. http://hdl.handle.net/10399/2922.
Testo completoAbstract (sommario):
This thesis presents an investigation into the performance of a Membrane Distillation (MD) system used for seawater desalination. The research is focused on the effects of intermittent use of the MD module when powered with a solar energy collector. The aim is to assess the feasibility of directly powering an MD unit with a fluctuating input from a solar collector. An investigation into the effect of temperature on the microstructure of the membrane was carried out. In a series of experiments, samples of PTFE membrane were imaged while heated from 17 C to temperatures between 60 C and 80 C. It was found that the membrane pore size increased with increases in temperature. When heated to 80 C the pore diameter increased by 44%. Intermittent use of the system would cause the temperature of the MD module to fluctuate, therefore altering the membrane microstructure. An investigation was carried out to determine the in fluence of intermittent MD operation on the flux and conductivity of the distillate. The system was tested after overnight shutdown periods and was also tested with short term `on/off' periods of between 5 and 20 minutes, simulating the intermittent output from a concentrated solar collector. It was found that as the module was heated, the distillate flux produced increased, while the distillate conductivity decreased. Conversely, when the module cooled, the flux decreased and the quality of the distillate worsened. This was the result of the dependancy of membrane pore size on temperature.
21
Darroch, Louise Jayne. "The production of dimethylsulphoxide (DMSO) in seawater". Thesis, University of East Anglia, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399808.
Testo completo
22
McCubbin, David. "Influence of seawater components upon actinide behaviour". Thesis, University of East Anglia, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359304.
Testo completo
23
Bellerby, Richard Garth James. "Seawater pH and the oceanic carbon cycle". Thesis, University of Plymouth, 1994. http://hdl.handle.net/10026.1/2089.
Testo completoAbstract (sommario):
The buffering of carbon dioxide in seawater and the intimate relationship between the carbonate system, air-sea gas exchange and biological productivity in the oceans is described. Characterisation of the carbonate system is enabled through the concurrent measurement of any two of the variables pH, alkalinity, TCO2 and pCO2. It is identified that to obtain the high density, high precision measurements necessary to better constrain carbon cycle models, with respect to estimating the effect of anthropogenic carbon release to the atmosphere, it will be necessary to develop in situ techniques for the measurement of pH and pCO2. The theory of pH scales and both potentiometric and spectrophotometric pH measurement is presented as well as a chronology of pH measurements at sea. The development of automated potentiometric and spectrophotometric techniques for the simultaneous, continuous, shipboard determination of seawater pH is documented and the performance of the instrumentation on a cruise to the Southern Ocean is reported. The potentiometric system was optimised for electrode response and incorporated increased temperature control and a novel flow cell to help reduce bubble effects and maintain the integrity of the liquid junction. Nevertheless, the technique illustrated very erratic potential and the data was of unacceptable quality. The spectrophotometric technique used a flow injection technique and phenol red indicator and showed a precision off 0.005 pH unit with a sampling frequency of about 25 h-1. A comparison of calculated alkalinity from the combinations pH and pCO2 and pCO, and TCO. 2 had a residual of 1.3 17.3 4equiv. kg-1 (n = 79) or about 0.32 %. The theoretical precision of the comparison calculated from the precisions of the methods used is 0.34 %. A comparison of in situ pH and that calculated from alkalinity and TCO2 showed a standard deviation of ± 0.016 with a standard error dependent on the choice of sulphate formation constant used to convert from the free to the total hydrogen ion concentration scale. Surface pH(SWS) at 25°C has been shown to vary significantly in the Southern Ocean from 7.65 in the Bransfield Strait to 7.85 in a area of intense biological activity associated with the South Polar Front (SPF). Throughout the majority of the cruise the surface waters were undersaturated with respect to carbon dioxide and the main control on pH was from the hydrography, although in areas of high chlorophyll concentrations, associated predominantly with the SPF, there existed considerable correspondence with biological activity. A previously unknown sink for atmospheric CO2 has been identified in the Bellingshausen Sea which has significant implications for our understanding of the global carbon budget. The spectrophotometric method is put forward as the method of choice for future measurements of seawater pH.
24
Søgaard, Andersen Martin. "Geochemical processes at a seawater-freshwater interface". Kgs. Lyngby, 2001. http://www.er.dtu.dk/publications/fulltext/2001/MR2001-201.pdf.
Testo completo
25
Reed, Jason. "Grower Attitudes Towards Water Management Strategies While Mitigating Seawater Intrusion| A Case Study of the Castroville Seawater Intrusion Project". Thesis, San Jose State University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10635156.
Testo completoAbstract (sommario):
The Salinas River Valley Watershed has endured the effects of seawater intrusion for decades caused by overpumping groundwater from the Salinas River Groundwater Basin. The Castroville Seawater Intrusion Project began delivering recycled water in 1998 with other water sources due to wells becoming too saline. One-on-one, in-person interviews with eighteen growers, who own or lease farmland within the Project’s service area, were conducted during a severe, statewide drought. Interview questions explored grower attitudes and concerns regarding their water supply, and the impact of management strategies on the mitigation of seawater intrusion. Two research questions were posed, exploring factors that influence grower acceptance of alternative water supplies, and whether environmental impacts affect their attitudes. Four prominent factors were found that influence grower acceptance of alternative water supplies: perceived need for water supply, changes to cost and/or water quality, information/education, and level of trust. The study also revealed three motivations of growers for choosing water supplies that do not increase seawater intrusion or contribute to adverse environmental impacts: protecting harvest/land, managing associated cost of operations, and avoiding increased regulations and/or oversight. Growers with fewer numbers of farms and smaller acreage of farmland tended to have a greater perceived need to acquire sustainable water supplies, while being more reluctant to implement water sources of lesser quality.
26
Jury, Christopher P. "Aragonite saturation state and seawater PH do not predict rates of calcification in a reef-building coral". View electronic thesis, 2008. http://dl.uncw.edu/etd/2008-3/r1/juryc/christopherjury.pdf.
Testo completo
27
Bin, Marshad Saud Mohammed H. "Economic evaluation of seawater desalination : a case study analysis of cost of water production from seawater desalination in Saudi Arabia". Thesis, Heriot-Watt University, 2014. http://hdl.handle.net/10399/2996.
Testo completoAbstract (sommario):
As a result of the increasing scarcity of freshwater resources worldwide, many countries have resorted to the use of unconventional sources, of which seawater desalination is the most significant, for meeting the supply-demand gap. However, despite the recorded advances in desalination technologies of recent decades, desalination remains a very expensive operation and operators will be greatly assisted if reliable means of predicting the costs are available to aid effective decision making during planning of new plants or the operation of existing plants. To achieve this, it is important to fully understand the factors that contribute to desalination costs, which could then be used to develop appropriate models for predicting costs that can support budgeting and/or cost reductions decision making. Consequently, this project has investigated the development of such models for predicting monthly production costs using data from 16 operational plants in Saudi Arabia. Monthly and annual data spanning 2001 – 2010 were collected on total water production, type of desalination technique, sea water salinity, product water salinity, energy consumption, and total (capital and operational) unit cost of water production. Because of the way in which the data were archived, some of the variables only had the annual totals for some of the years, which made them unsuitable for the monthly scale adopted for the analyses. Consequently, disaggregation schemes based on several variants of the method of fragments widely used in hydrological studies were used to obtain monthly data from the annual data. Exploratory analysis showed that the monthly costs correlated most with the total water production, which then formed the lone independent variable for various tested regression model formulations. In general, an inverse regression model performed best during both calibration and validation. To enhance the usefulness of the predictive model for decision making, uncertainty limits of the predictions were constructed using a Monte Carlo simulation approach involving the seasonal, lag-1 autoregressive generation of equally likely realisations of the available historic records that have been transformed to remove the skewness. Extensive testing of the data generation technique showed that the assumed lag-1 auto-regressive dependence structure was adequate. This study thus provides for the first time a predictive model for costs of desalination in Saudi Arabia and its uncertainty range for effective budgeting and operational management. Although the models were developed using Saudi Arabia data, the fact that only one independent variable was used means that the replication of the methodology in other desalination-intensive countries can be readily carried out.
28
Allen, Peter John. "Seawater adaptation in juvenile green sturgeon, Acipenser medirostris /". For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2005. http://uclibs.org/PID/11984.
Testo completo
29
Harrison, Catherine J. "Bench-scale testing of seawater desalination using nanofiltration /". abstract and full text PDF (free order & download UNR users only), 2005. http://0-wwwlib.umi.com.innopac.library.unr.edu/dissertations/fullcit/1433104.
Testo completoAbstract (sommario):
Thesis (M.S.)--University of Nevada, Reno, 2005."August, 2005." Includes bibliographical references (leaves 80-84). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2005]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.
30
Davis, Charles A. "Magnetic fields generated by internal ocean seawater motion". Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28337.
Testo completoAbstract (sommario):
This thesis models induced magnetic fields from the motion of seawater in the Earth's magnetic field analytically and compares the results to arctic on-the-ice magnetic fluctuation measurements. The oceans have various types of internal motions, such as internal waves and turbulence. This motion of sea water, which is a conductor, in the earth's magnetic field induces a current density. The current density, in turn, induces its own magnetic field. This thesis models internal waves and upper layer ocean turbulence analytically. The corresponding induced magnetic fields are calculated using a static form of Maxwell's equations and parameters for the Arctic are inserted. comparisons are made with measurements from the Arctic Internal Wave Experiment (1985). The predicted fields from internal waves have magnitudes that are measureable and of the same order of magnitude as ionospherically generated fields, The predicted fields from turbulence are several orders of magnitude smaller than ionospherically generated fields. Besides giving information about internal motions in the ocean, the seawater induced fields are a noise source in magnetic anomaly detection
31
Jones, Charles Edward. "Strontium isotopes in Jurassic and Early Cretaceous seawater". Thesis, University of Oxford, 1992. http://ora.ox.ac.uk/objects/uuid:fe3733bd-8e31-4bba-a78b-6d8275a0075f.
Testo completoAbstract (sommario):
The collection and analysis of a large number of belemnites and oysters with excellent biostratigraphic and diagenetic control has resulted in a highly detailed determination of the seawater Sr-isotope curve through the Jurassic and Early Cretaceous. The new data confirm the broad trends established by previous work, but the much sharper resolution of the new data allows the application of Sr-isotope stratigraphy with an optimal stratigraphic resolution of ± 1 to 4 ammonite subzones (± 0.5 to 2 Ma). The data show a general decline from the Hettangian (Early Jurassic) to a minimum in the Callovian and Oxfordian (Middle/Late Jurassic). This is followed by an increase through the Kimmeridgian (Late Jurassic) to a plateau reached in the Barremian (Early Cretaceous). In addition, there are major negative excursions in the Pliensbachian/Toarcian (Early Jurassic) and Aptian/Albian (Early Cretaceous). Stable isotope data collected from belemnites and oysters have resulted in the most extensive Jurassic δ13C and δ18O database to date. While both the carbon and oxygen data appear to give reasonable marine signals, the scatter in the data suggests that future research must document possible biological fractionation effects and develop better indicators for the diagenetic alteration of 613C and 6i 8O. The final chapter documents an unexpected correlation between sudden shifts in the Sr-isotope curve, the occurrence of positive 513C excursions, and the eruption of flood basalts. In the Jurassic and Cretaceous there is a correlation in time between sudden downward shifts in the Sr-isotope curve (Pliensbachian, Aptian, Cenomanian/Turonian), the occurance of positive 613C excursions, and the eruption of flood basalts. Each of these major downward shifts in the Sr-isotope curve is followed by a sudden upward shift, which although associated with a positive 613C excursion is not associated with an episode of flood basalt volcanism. In the Cenozoic the Sr-isotope curve no longer displays downward shifts, but the correlation continues between the occurrence of flood basalts and positive 513C excursions. Several lines of evidence suggest that the eruption of flood basalts is associated with pulses of hydrothermal activity, and that this hydrothermal activity brings about the conditions necessary for the genesis of carbon-burial events.
32
Smallwood, Russell. "Fretting fatigue of steel roping wire in seawater". Thesis, University of Nottingham, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328387.
Testo completo
33
Cruz, Isabel. "Distribution of organochlorines between seawater and suspended solids". Thesis, University of Aberdeen, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306222.
Testo completoAbstract (sommario):
An analytical method was developed for the experimental investigations. This included sampling, separation into fractions, clean-up and determination of the organochlorines in suspended solids and seawater. A sampling apparatus was designed and built in our laboratory, capable of sampling seawater up to 28 l, and separating the suspended particles prior to the extraction of the filtered water with organic solvent. The analytical method for the determination of chlorinated biphenyls (CBs) and a large number of organochlorine pesticides in sediments was readily available in our laboratory. In addition, a method for the determination of pentachlorophenol (PCP) in seawater and solids was developed. The complete analytical method for the determination of particulate and dissolved organochlorines in the seawater column, at the ng l-1-pg l-1 level, was validated. Small scale experiments were not able to replicate the environment, therefore, a large scale experiment was undertaken in a Loch in the NW of Scotland. Experimental bags, 60,000 l capacity, were attached to a floatable frame and filled with seawater, then contaminated sewage sludge was dumped on it. A sampling strategy was designed, and a set of samples was obtained to investigate the factors affecting the partitioning, and the kinetics of the partitioning, between suspended solids and seawater. The experimental data from the analysis of the samples were used to propose a simple mathematical model describing the changes in the concentrations of particulate and dissolved organochlorines over the time of the experiment. The mathematical modelling provided values for the desorption rates and the partition coefficients of the nonequilibrium for the individual organochlorines. These calculated parameters were used to elucidate the possible trends related to physico-chemical properties of the organochlorines, and to propose the process affecting the organochlorine-particle interactions: intra-organic matter diffusion.
34
Cummins, David Ian. "The strontium isotropic composition of Lower Carboniferous seawater". Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316761.
Testo completo
35
Zhou, Y. "Reconstructing the strontium isotopic composition of Neoproterozoic seawater". Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/10039126/.
Testo completoAbstract (sommario):
The Tonian Period (1000 - c.720 Ma) followed a long interval of relative stasis, in terms of climate, carbon isotopes and biological evolution, and led into the Cryogenian Period of environmental extremes and instability. Despite its pivotal situation, the Tonian Period is still relatively understudied, and this is partly due to the lack of robust age constraints in key Proterozoic successions around the world. The fossiliferous Neoproterozoic strata of the North China craton were until recently thought to be of Ediacaran age. However, fossil evidence and new geochronological constraints combine to show that most of the ‘Qingbaikou’ System, which reaches a great thickness in some areas, was deposited between c. 980 and c. 920 Ma. The isotopic signature of these strata confirms their Tonian age, showing typical moderately high 13C values together with low 87Sr/87Sr ratios, < 0.7065. Another characteristically Tonian feature is the unusually widespread abundance of early diagenetic ‘molar-tooth’ low-Mg calcite microspar. In this study, I compare MT samples with their surrounding ‘bulk’ matrix in correlative successions on the North China craton in order to 1) demonstrate their propensity to preserve a primary seawater isotopic signature; and 2) reconstruct, together with published data, the strontium (and carbon) isotopic evolution of early Tonian seawater. Second-order fluctuations of less than ~0.001 are superimposed on a general 87Sr/87Sr rise from ~0.7052 to ~0.7063 by c. 920 Ma, accompanied by a profoundly negative carbon isotope excursion. Increased chemical weathering has been linked with both climatic and carbon isotope instability, and this study indicates an earlier beginning to such carbon cycle perturbations, which coincide with early stages of supercontinent rifting, as evidenced by the newly dated Dashigou igneous province of North China. These and other new and published data are used to reconstruct and reinterpret the strontium isotopic evolution of Neoproterozoic seawater.
36
Karam, Hanan Nadim. "Seawater circulation in coastal aquifers : processes and impacts". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78141.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 150-154).
This thesis explores the subterranean domain of chemical cycling in coastal oceans abutting permeable aquifers, where transport through sediments is dominated by advection, rather than diffusion. We investigate the mechanisms by which seawater circulates in the subsurface over a range of spatio-temporal scales, and the chemical reactions to which this circulation is coupled. Seawater circulation in coastal aquifers is driven by salinity variations in pore water as well as by the effects of temporally variable forcings at both terrestrial (variable recharge) and marine (tides, waves and secular sea level changes) boundaries. It is coupled to the transport of biogeochemically reactive species through the subsurface and their exchange between the sediments and the water column. Our understanding of how different forcing mechanisms interact to determine spatial scales and residence times of subsurface seawater circulation, as well as temporal patterns and rates of aquifer-surface water exchange has thus far been very limited. The large range in the spatial and temporal scales of flow dynamics associated with different forcings challenges our ability to comprehensively observe and monitor their associated seafloor fluxes. In this thesis, we present a novel, homemade instrument for high-resolution, long-term monitoring of seafloor fluxes, designed to address this challenge. Two-year deployments of several such instruments at Waquoit Bay, MA, produced the most comprehensive datasets on seafloor fluxes available to date, multiplying the length of published time series by tenfold. The length and integrity of the datasets permit the use of spectral analysis to investigate distinct frequency components of seafloor fluxes and quantify their relationship to various forcing mechanisms. The temporal and areal coverage of the datasets allow us to distinguish the contributions of different forcings to observed fluxes, as a function of distance from shore and season. Furthermore, we discuss new insight derived from the data into the physics underlying observed seafloor fluxes and their associated subsurface circulation processes. Additionally, we describe results from an independent but related project to characterize chemical dynamics associated with seawater circulation in beach sand at Waquoit Bay. We present evidence for the important contribution of this circulation to the nitrogen budget of the Bay.
by Hanan Nadim Karam.
Ph.D.
37
Thistlethwaite, Christopher. "Behaviour of massive reinforced concrete sections in seawater". Thesis, University of Dundee, 2014. https://discovery.dundee.ac.uk/en/studentTheses/4819cd1e-a5ce-48c2-a982-874196b3e8d9.
Testo completoAbstract (sommario):
This study combined research available through literature with extensive experimental studies and substantial physical modelling to estimate the remaining ultimate life of large offshore reinforced concrete structures. Although much research has focussed on concrete degradation due to chloride ingress, corrosion of permanently submerged concrete is regarded as negligible due to the long-assumed apparent worst case of tidal or splash zone exposure. Around 350 specimens were tested with a further 200 exposed for further testing by future research groups. Specimens ranged in size from standard cubes to various beam lengths up to 1.5 metres, allowing for material and structural properties to be assessed. My original contribution to knowledge in the sector enhances the fundamental understanding of corrosion in subsea concrete, challenging the generally held belief of negligible corrosion. Results and modelling provides an improved ability to ultimately estimate the longevity of fully submerged offshore reinforced concrete. Throughout this thesis, the results from experimental works, carried out as a direct result of the lack of data or information in literature, are reported, assessed and then utilised to provide updated ultimate life estimations. With the current offshore concrete structures currently coming to the end of their service life, and the likelihood of further offshore development using concrete for the renewables sector, understanding the long-term degradation is vital in determining the most effective decommissioning and derogation options. The research carried out directly provides detailed information of the likely time-to-failure, allowing for an informed decision to be made on operational and decommissioning plans. Experimental work was carried out over four main phases; corrosion initiation due to bulk diffusion of chlorides (Phase I), corrosion propagation in low oxygen environments (Phase II), corrosion in statically and dynamically cracked sections (Phase III) and structural response of heavily corroded individual and lapped bar sections (Phase IV). Phase I work shows a marked difference between submerged exposures to seawater as opposed to NaCl solution, the unsuitability for accelerated testing with seawater and the likelihood of rapid initiation in offshore structures. Further experimental works through Phases II and III found that although exposed to low oxygen concentrations, reinforcement corrosion continued at significant rates. A variation between anode sizes on the reinforcement is noted, but critically the cross sectional area of the steel was still reduced, albeit in fewer locations. Corrosive products were visibly different, with fewer expansive products, if any, present. Additionally, this study further highlights the importance of cracking on corrosion, currently ignored by recent model codes, such as the fib Model Code 2010, up to 0.2mm crack width. A linear relationship was found between crack width and corrosion rates, with cracking above 0.1mm considered significant. The loss of cross sectional area due to propagation was determined for the given environment, and consequently further studies were initiated in an attempt to determine the relationship between this corrosion propagation and the reduced serviceability or ultimate life of concrete beams. Serviceability, defined by beam stiffness, was reduced due to bond loss along reinforcement. Most importantly, however, results prove that the loss of cross sectional area to be the critical influence on loss of ultimate life. Initial estimates on the remaining ultimate life of the large offshore structures support early rough work that the structures would last centuries. This thesis, however, has shown this is due to the ability of concrete structures with such large volumes of steel to continue to ultimately withstand loading at high corrosion percentages and not due to negligible corrosion, or long initiation periods, commonly suggested in submerged, low oxygen environments.
38
Van, der Meulen Karen. "Computer modelling of the chemical speciation in seawater". Master's thesis, University of Cape Town, 1990. http://hdl.handle.net/11427/17287.
Testo completoAbstract (sommario):
Includes bibliographical references.The primary aim of this thesis is to establish a computer model of the chemical elements in seawater and to use this model to gain insight into the chemical processes controlling dissolution, precipitation, redox levels and coordinative interactions in surface seawater. In order to accomplish this task a relatively extensive database consisting of about 580 complexation equilibria arising from 32 inorganic and 10 organic components has been set up. Constants have been selected from critical compilations. Included in these equilibria are solubility products for the formation of potential solids, redox reactions and interactions with the atmospheric gases carbon dioxide and oxygen.
39
Mary, Makokha. "Seawater intrusion and contaminant transport in coastal aquifers". Kyoto University, 2008. http://hdl.handle.net/2433/136601.
Testo completoAbstract (sommario):
Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第13874号
農博第1689号
新制||農||953(附属図書館)
学位論文||H20||N4341(農学部図書室)
UT51-2008-C790
京都大学大学院農学研究科地域環境科学専攻
(主査)准教授 小林 晃, 教授 河地 利彦, 教授 川島茂人
学位規則第4条第1項該当
40
Miranda, Marcos. "Small-scale wind-powered seawater desalination without batteries". Thesis, Loughborough University, 2003. https://dspace.lboro.ac.uk/2134/10708.
Testo completoAbstract (sommario):
Potable water is a commodity taken for granted by many in modem society. In places where it is not naturally available, it is usually produced by adequate processing of the supply from other sources, as is the case with seawater desalination. Such processes require an energy supply, which just as well may not exist at many of these locations. In view of the above, this w~rk focuses on the study of two well-established technologies and their integration: water desalination by Reverse Osmosis (RO) and electricity generation using Wind Energy. Based on the premise that no energy backup or storage devices would be employed, two alternative wind-powered RO system configurations are proposed. Their components are individually described and modelled. Control strategies are devised for both systems, aiming at making the best possible use of the energy available. The expected performances of both systems are assessed through simulation of computer models. Based on the simulated performance results, one of the systems is chosen for further development. A prototype system is built and experimental tests carried out. The design of the prototype is detailed and the results obtained are presented. In the light of these results, the developed model is validated and the viability of the system is discussed. Finally, practical implementation issues are discussed; a case study is introduced, including performance predictions and a simplified economic analysis presented.
41
Nafey, Ahmed Safwat M. T. "Design and simulation of seawater thermal desalination plants". Thesis, University of Leeds, 1988. http://etheses.whiterose.ac.uk/15208/.
Testo completoAbstract (sommario):
Water is the most important chemical component on Earth. Seawater distillation processes have a considerable promise as a technique suitable for producing large scale quantities of potable water from the seawater. Distillation process flowsheets consist of a number of interconnected units. The development of the mathematical model describing the behaviour of these units, and the subsequent solution of this model are fundamental steps in process flowsheeting. The first objective of this work is to develop a specialized flowsheeting program for performing design and simulation calculations for different types and configurations of seawater distillation processes. Many numerical methods have been used for solving linear and nonlinear sets of equations representing distillation processes. Most of these methods involve the direct manipulation of the mathematical model equations without exploiting the special properties, such as the sparsity and the weak nonlinearities, of these equations. The second aim of this study is to develop a new approach taking advantages of these properties. Hence, the model equations can be linearized, and grouped according to the variable type. These groups can then be solved by linear matrix technique. The performance of the developed program is investigated by solving many distillation process problems. The results from design and simulation calculations for large practical desalination plants are discussed. In addition to that the convergence characteristics of the new approach (such as stability. number of iterations. computing time. sensitivity to starting values, and general ease of use) are presented. Also. the validity of the approximation assumptions proposed to develop the new approach is examined.
42
Dai, Yuhao. "Reconstructing seawater carbonate chemistry using foraminiferal B/Ca". Phd thesis, Canberra, ACT : The Australian National University, 2018. http://hdl.handle.net/1885/144599.
Testo completoAbstract (sommario):
Planktonic B/Ca holds promise of reconstructing the surface
seawater carbonate chemistry, which is linked to the past levels
of atmospheric partial pressure of CO2. However, it is still not
clear to what extent the carbonate chemistry control on
planktonic B/Ca is complicated by physiological activities of
foraminifera. In this thesis, the environmental controls on B/Ca
in two planktonic foraminiferal species, Globigerinoides ruber
(white) and Globigerinoides sacculifer (without final sac-like
chamber), are examined using core-top samples from the Atlantic
Ocean. For an accurate estimation of the ambient calcification
environments, the calcification depths and seasonality of the
studied species at these core-top locations are determined by
planktonic Mg/Ca. The dissolution effect on B/Ca, which is
evident from planktonic B/Ca data from three depth transects,
proves to have little impact on the interpretation of planktonic
B/Ca data from the Atlantic core-tops. While the carbonate
chemistry control on planktonic B/Ca can be detected from these
core-top data, a strong calcification rate control on planktonic
B/Ca is demonstrated by the correlation between B/Ca and Sr/Ca,
where Sr/Ca is employed as an indicator of the calcification
rate. This calcification rate control on planktonic B/Ca
complicates the direct link between planktonic B/Ca and seawater
carbonate chemistry. Nevertheless, based on the different
responses of B/Ca in the two studied species to the calcification
rate, it is possible that B/Ca in some species are less
susceptible to this influence, and thus can be employed for
carbonate chemistry reconstructions.
Benthic B/Ca is a recently developed quantitative proxy for
deepwater carbonate ion concentration ([CO32-]). In this thesis,
deepwater [CO32-] variations during the last 150 thousand years
are reconstructed using two cores from the deep Southwestern
Pacific, a critical but not fully investigated region to regulate
the carbon inventory in the deep ocean. Since Marine Isotope
Stage (MIS) 5a, the deep the SW Pacific [CO32-] varied in concert
with benthic carbon isotopes (δ13Cb). These covariations, on the
timescale of ~10 kyr, are similar to those observed in the deep
Atlantic. This suggests that the deep SW Pacific [CO32-] could be
affected by changes in the Atlantic Overturning Circulation and
the biological pump. However, the deep SW Pacific [CO32-] showed
little change during Termination II (T II), despite that
variations of δ13Cb, neodymium isotopes (εNd), and
foraminifer-bound nitrogen isotopes (δ15N) were similar to those
during Termination I (T I). This difference is interpreted as the
result of coral reef regrowth on continental shelves, which
decreased the whole ocean [CO32-] and counteracted the [CO32-]
increase due to the influences from Atlantic Overturning
Circulation and the biological pump changes during T II.
43
Meskhidze, Nicholas. "Iron mobilization in mineral dust and the possible effect of Asian pollution on C-uptake in North Pacific Ocean". Diss., Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04082004-180333/unrestricted/meskhidze%5fnicholas%5f200312%5fphd.pdf.
Testo completo
44
Taylor, Kelly Lynne. "Beach sediments : a source of dissolved organic carbon and nitrogen species to the coastal ocean /". Electronic version (PDF), 2005. http://dl.uncw.edu/etd/2005/taylork/kellytaylor.pdf.
Testo completo
45
Vishwanathappa, Manohar D. "Desalination of seawater using a high-efficiency jet ejector". Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/2463.
Testo completoAbstract (sommario):
The ability to produce potable water economically is the primary focus of seawater desalination research. There are numerous methods to desalinate water, including reverse osmosis, multi-stage flash distillation, and multi-effect evaporation. These methods cost more than potable water produced from natural resources; hence an attempt is made in this research project to produce potable water using a modified high-efficiency jet ejector in vapor-compression distillation. The greater efficiency of the jet ejector is achieved by properly mixing propelled and motive streams. From experiments conducted using air, the pressure rise across the jet ejector is better in case of one or two mixing vanes and the highest back pressure (pinch valve closed 83.33%). At other pinch valve closings, the air velocity through the jet ejector was high, so the extra surface area from the mixing vanes caused excessive friction and lowered the efficiency.
46
Singh, Harshmeet. "The corrosion behaviour of aluminium alloy B206 in seawater". Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/56551.
Testo completoAbstract (sommario):
Aluminium alloy B206 is one of the strongest and toughest alloys in the cast aluminium family. Although it is light and has excellent low cycle fatigue strength, AA B206 has been known to perform adversely due to its poor corrosion resistance. Thus corrosion has been identified as one of the major issues that jeopardizes the long-term use and performance of B206. The corrosion behaviour of B206 in seawater is studied through immersion testing and electrochemical techniques such as Potentiodynmaic Polarization, Potentiostatic Polarization, Cyclic Potentiodynmic Polarization and Linear Sweep Thermmametry in two different solutions, namely natural seawater and simulated seawater, at various temperatures. Techniques like Optical Microscopy, Energy Dispersive X-ray Spectroscopy and Scanning Electron Microscopy have been used to investigate the microstructure and surface morphology before and after the electrochemical tests. Heat treatment has been performed on the as-received samples using RRA and T7 heat treatment techniques to compare the corrosion behaviour of the former with the latter using electrochemical techniques and image analysis. Lastly, hardness tests have been performed on various heat treated and as-cast samples to establish a comparison in mechanical properties. This study shows that the extent of B206 corrosion depends on the oxidizing nature of the seawater environment i.e. low or high redox potential rather than on the temperature of the seawater. Natural seawater is more aggressive than simulated seawater. Also, heat treatment improved the corrosion resistance as compared to as-cast B206 which was determined by the values of corrosion current density and surface analysis. Furthermore, heat treatment has led to better mechanical properties as determined by hardness tests.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
47
Azmy, Karem. "Isotopic composition of Silurian brachiopods, implications for coeval seawater". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq20988.pdf.
Testo completo
48
Wong, Yiu-ming, e 黃耀明. "Biofouling treatment of seawater cooling systems in Hong Kong". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B42574778.
Testo completo
49
Winters, Tim. "Oxygen isotope ratios in seawater of the North Atlantic". Thesis, University of East Anglia, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323347.
Testo completo
50
Takeuchi, M. "Fretting and fatigue of a roping steel in seawater". Thesis, University of Nottingham, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384690.
Testo completo