1,720,979 research outputs found
Coupling of a nuclear reactor to hybrid RO-MSF desalination plants
No full textEnergy requirements in desalination plants can be supplied by coupling desalination units with nuclear reactors. Multistage flash (MSF) plants often use low-pressure steam as an energy source. The energy consumption in MSF plant depends on the distillate flow rate and the plant performance ratio. Reverse osmosis (RO) plants are operated by electrical power to derive the high-pressure pumps and other plant auxiliaries, mainly the pretreatment processes. RO power consumption depends mainly on water recovery and the working pressure. Low pressure and temperature steam extracted from nuclear heating reactors (NHR) may be used for supplying the necessary energy to derive the MSF units. Electricity can be generated from the nuclear power reactor (NPR) to derive the high-pressure pumps of the RO desalination plants. Coupling RO and MSF with nuclear steam supply system (NSSS) will yield some economical and technical advantages. The hybrid RO MSF system has potential advantages of a low power demand, improved water quality and possible lower running cost as compared to stand-alone RO or MSF plants. Developing the most appropriate plant configuration of nuclear reactor and desalination process is an important task that will determine the feasibility of nuclear desalination. The optimum coupling of hybrid RO MSF desalination processes with nuclear power plant will be presented in this paper
Removal of gaseous pollutants in wet atmosphere
No full textGaseous pollutants such as S02 and NO xonce emitted to the atmosphere is oxidized to sulphate and nitrate through gaseous and aqueous phase processes. The absorption and desorption of gaseous pol-lutants by water droplets is the beginning of the removal process of these gases. However, absorption and desorption involve a complex mechanism which incorporates dissolving and extraction of these species in and out of water droplets. This paper will discuss the possible mechanism of absorption as an example of the behaviour of the atmospheric pollutants. Altough, Saudi Arabia has a dry atmosphere in general, the proposed phenome-non is an important one in the coastal cities specially in the summer
Potential of nuclear desalination in the Arabian Gulf countries
No full textArabian Gulf countries are located in an arid area with limited water resources. Hydrological investigations point to large resources of underground water, but they are saline and need to be desalted. The best choice for providing fresh water in the Arabian Gulf countries is through seawater desalination with ground water as a back up. About 65% of desalination plants that are in operation worldwide are located in the Arabian Gulf countries, most of which are the dual-purpose multistage flash (MSF) plants, producing power and water. Reverse osmosis (RO) is used mainly for brackish water treatment and a limited number of multiple effect distillation (MED) plants are used in the Arabian Gulf countries. The use of nuclear desalination is practically essential in these countries where massive quantities of water are desalinated and there is a fast increase in power demand. There is no technical impediment to the use of nuclear reactors for supply of either heat or electricity or both to a desalination plant. However, the cost effectiveness of nuclear desalination is a site dependent matter. The type of desalination process and the size and type of the nuclear reactor have to be determined based on the specific site data. MSF plants are considered as energy intensive processes where energy cost is a major controlling parameter in the overall cost of desalination. Oil price fluctuations affect the cost of desalted water significantly, whereas nuclear power offers long term availability of indigenous fuel as well as long term fuel price stability. It has minimal environmental impact compared with other conventional desalination processes. This paper will discuss the potential of application of nuclear desalination in the Arabian Gulf countries. Various processes will be reviewed and most appropriate method selected.
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Prediction of charge density for desal-HL nanofiltration membrane from simulation and experiment using different Ion Radii
No full textSolute separation characteristics of commercial nanofiltration (NF) membrane Desal-HL were investigated. Donnan steric pore model (DSPM) was applied to the experimental data to study the charge density at the surface of the membrane for various solute radii namely Stokes-Einstein, Born, and Pauling. Sodium chloride and magnesium chloride were used as simple solutes. The effect of pH was studied for all the solutes. Correlations for the charge density for each radius were proposed. It was found that the charge density changes considerably with the ion radius, and, consequently causes remarkable variations in prediction of ions rejectionsion.
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