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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Simulering av hydrodynamiska förlopp för KAS vid kraftverksdammar / Simulation of Hydrodynamic Processes for the Overtopping Protection System at Hydropower Plants

Karlsson, Erik January 2013 (has links)
I detta projekt har det kontrollerande avbördningsskyddet för vattenkraftverk, förkortat KAS, studerats närmare. KAS finns installerat vid många större vattenkraftverk och har till uppgift att automatiskt aktivera öppning av dammluckorna ifall vattennivån skulle stiga över dämningsgräns och både den ordinarie nivåregleringen och manuell reglering skulle utebli. På så sätt kan överströmning av dammen med eventuellt dammbrott som följd förhindras. Eftersom KAS är det yttersta skyddet ställs extra höga krav på tillförlitlighet. Därför behöver de elektiska och mekaniska komponenter som ingår i systemet vara robusta, väl beprövade och ha en lång livslängd. Dessutom ska systemet vara utformat på ett sådant sätt att även om ett fel skulle uppstå ska inte det leda till att hela systemet förlorar sin funktion. Minst lika viktigt som konstruktionen är att de parametrar som styr skyddssystemets funktion är rätt inställda. Det kan bland annat handla om vilken vattennivå som KAS ska aktiveras eller stängas för och om olika luckor ska ha olika aktiveringsnivåer. Vanligtvis beror dessa parametrar på varandra. Eftersom systemet är helt automatiskt måste man vid inställningen av parametrarna ta hänsyn till alla de driftsituationer och felhändelser som kan tänkas inträffa. Detta är särskilt utmanande för system av dammar som ligger geografiskt nära varandra. Det korta avståndet leder till att dammarnas magasinstorlek är liten vilket innebär att stignings- och sänkningsförlopp kan bli väldigt snabba. Det innebär dessutom att om dammluckorna öppnas vid en damm så kommer också åtgärder vid de intilliggande dammarna behöva göras inom kort tid och därför kan kommunikation mellan dammarnas KAS-system vara nödvändig. Fjärrkommunikation riskerar däremot samtidigt att minska funktionssäkerheten och bör därför så långt som möjligt undvikas. Tre dammar som ligger nära varandra är Porjus, Harsprånget och Ligga i Stora Luleälven. I detta projekt har en numerisk modell för att simulera hydrodynamiska förlopp för den aktuella älvsträckan utvecklats i beräkningsprogrammet MIKE 11. Särskild vikt har lagts på att korrekt beskriva flödet genom dammluckor och hantera de numeriska instabiliteter som uppstår vid bland annat simulering av snabba flödesförändringar och uttorkad älvfåra. Med hjälp av simuleringar och beräkningar har en metodik kunnat utvecklas för hur inställningar för KAS kan väljas för system av intilliggande dammar. Metoden bygger på att varje lucka tilldelas en individuell aktiverings- och stängningsnivå. Avståndet mellan aktiveringsnivåer anpassas till vattenytans stigningshastighet för olika flöden och tiden det tar att öppna luckan. Resultaten visar att om inställningarna för de enskilda dammarna väljs rätt kan ett gynnsamt förlopp erhållas för de flesta fallen. Vissa kombinationer av flöden och felhändelser riskerar däremot att leda till stora svallningar och att dämningsgräns överskrids markant inom kort tid efter felhändelsen. Om dessa följder ska undvikas med hjälp av automatik behöver tillrinning uppströms stoppas och magasin nedströms förtappas genom kommunikation mellan dammarnas KAS-system. Simuleringar är ett lämpligt verktyg för att studera de förlopp som kan uppstå vid magasinhantering och för att finna en lämplig reglerstrategi. De exakta värdena för de parametrar som beräknats däremot bör ej tillämpas innan dess att modellens noggrannhet validerats ytterligare. / This Master thesis project concerns the dam overtopping protection system for hydropower plants, abbreviated DOPS. The system is installed at many major hydroelectric power plants and is designed to automatically initiate opening of the spillways if the water level would rise above the retention level and in the absence of both regular automatic control and manual control. In this way, overtopping of the dam with possible dam failure as a result can be prevented. A numerical model for simulating hydrodynamic processes for Porjus, Harsprånget and Ligga in Stora Luleälven has been developed in the computational software MIKE11. Particular emphasis has been on accurately describing the flow through spillways and handling the numerical instabilities that arise from rapidly varying flow and driedout flood beds. Through simulations and calculations, where a large number of scenarios have been tested, a methodology has been developed for setting parameters of the DOPS. This is non-trivial since the dams are geographically close to each other and have limited storage capacity. The method for setting parameters is based on the principle that each spillway is assigned with an individual activation and closing level. The vertical distance between activation levels is adjusted to the water surface rising velocity for different flow regimes and the time it takes for the gate to open. The results show that if the settings for the individual dams are chosen correctly, apropitious progress is achieved for most cases. Some combinations of flow and error events could however lead to large billows and that the retention level is exceeded significantly within a short time after the initial error event. If these consequences are to be avoided using an automatic system, upstream discharge needs to be stopped and the spillways of the dam downstream need to be opened in advance through communication between the DOPS of the dams.
2

Kas und Kai : dialektale und chronologische Probleme im Zusammenhang mit Dissimilation und Apokope /

Lüttel, Verena. January 1981 (has links)
Thèse : Lettres : ZÜrich : 1972.
3

Interactions of mtFabH with its Substrates and Inhibitors Reveal Novel Mechanistic Insights

Sachdeva, Sarbjot Singh 01 January 2007 (has links)
Tuberculosis emerged from its grave to be one of the deadliest diseases of the present time after recently developing a synergy with AIDS. A fatty acid condensing enzyme-mtFabH has been proposed to connect the key processes involved in biosynthesis of mycolic acids, an important component of mycobacterial cell wall. It condenses long acyl Coenzymes A (CoA; up to C20CoA) with malonyl Acyl Carrier Protein (ACP) to form the elongated β-ketoacyl-ACP which further undergoes rounds of elongation to form mero-mycolate branch of mature mycolic acids. Owing to its proposed central position in mycolic acid synthesis, mtFabH has attracted considerable attention as a good anti-mycobacterial target.In this study, we utilized important biochemical tools such as site directed mutagenesis, mass spectrometry and X-ray crystallography to address some of the key unanswered questions regarding the intricate workings of mtFabH. We solved the first co-crystal structure of substrate C12CoA with mtFabH and further analyzed the substrate specificity of this acylation step. This structure depicts the mode of acyl-CoA binding in mtFabH channels; and its comparison with the parallel E.Coli-acetyl CoA structure provides important similarities and differences in substrate binding in these two FabH enzymes. It also posed an important question about the trajectory of long acyl chain CoA into the deep and "seemingly closed" substrate binding pocket of mtFabH. By utilizing disulfide-based inhibitors, we showed that large conformational changes are necessary to facilitate ligand trafficking in mtFabH while the high catalytic turnover rate of the enzyme is maintained. We also proposed the most likely location of the involved loop.A much faster and less cumbersome assay for mtFabH was also developed and it was utilized to characterize a series of inhibitors. This assay utilizes the commercially available radioactive malonyl-CoA in lieu of malonyl-ACP, the physiological substrate, and thus can serve as ACP independent assay for mtFabH.These studies further our understanding of the biochemistry of mtFabH, which along with the faster assay could be helpful in designing potent mtFabH inhibitors as anti-tubercular agents in the future.
4

Lading of the Late Bronze Age ship at Uluburun

Lin, Shih-Han Samuel 29 August 2012 (has links)
The Uluburun shipwreck was discovered in 1982 when a Turkish sponge diver informed the Institute of Nautical Archaeology (INA) of his discovery of metal biscuits with ears. INA archaeologists recognized this as a description of oxhide ingots, a clear indication of a Late Bronze Age site. This find was of considerable interest as very little is known about seafaring, long distance trade, and ship construction during the Late Bronze Age, except for a glimpse provided by the Cape Gelidonya shipwreck excavated in 1960 by George Bass. The site at Uluburun revealed only a handful of disarticulated ship fragments; nevertheless, a meticulous study of these timbers and the distribution of the cargo and shipboard items on the seabed resulted in a hypothetical, but carefully guided, reconstruction of the ship and the lading of its cargo. The artifacts recovered from the Uluburun shipwreck are unlike those discovered on land in quality of preservation as well as the quantity found. Items pertinent to this study include 354 copper oxhide ingots (approximately 10 tons), 152 copper bun ingots (nearly 1 ton), 110 tin ingot fragments (approximately 1 ton), 175 glass ingots (approximately 0.3 tons), 150 Canaanite jars (approximately 2 tons if filled with water), 10 large storage jars (pithoi) (approximately 3.5 tons if filled with water), approximately 51 Canaanite pilgrim flasks, 24 stone anchors (3.3 tons), nearly 1 ton of ballast stones, and the hull remains itself. Two computer programs, Rhinoceros and PHASER, were used to visually model the artifacts and ship in three-dimensions and to systematically test various hull shapes and lading arrangements in a range of hydrostatic conditions. Tests showed that a hull measuring 15 x 5 x 2 m would be capable of carrying the estimated 20 tons of cargo and shipboard items recovered from the wreck at a draft of 1 m, with sufficient freeboard to allow six passengers to stand on one side of the vessel without compromising the stability of the ship. / Institute of Nautical Archaeology
5

Research of the management function of the steps in Chinese enterprise ~ Comparison of the regional enterprises of both sides of the Straits

Chiu, Ching- huei 05 September 2006 (has links)
Globalization is in highly competitive era, talents are company's most important assets, the especially fine one hits the managerial cadre of the steps and is managed with one of the key factors of growing up continuously continuously forever by the company even more, this research object restricts the trade (industry ) , restricts the department , the steps executive is research objects that direct against Chinese enterprise of areas of both sides of the Straits (Jiangsu and Taiwan ), collect and research and analyse samples. With the research of the management function, hope to find out the management function which the steps executive should possess in the company objectively, offer enterprises to recruit and select the just , reference foundation of fostering and forming talents, it set up select Human Resource Department , not educating, with, leave managerial talent the systems at, probe into the result tentatively , expect that can propose a nucleus administrator's function way for enterprise's firm name in most key key management functions needed. So study the steps executive's management function in enterprises , operate for improving enterprises with the theoretical foundation of having the essence of national competitiveness and discussion value. This research questionnaire investigation analysis result is found, in Taiwan in the steps administrator studies in the management function index , and ' mood control ability ' superior to continent managerial cadre of the steps among the district in innovate with learning ability , surmount ability oneself.
6

Assessing the Potential Needs for Telehealth in Papua New Guinea (PNG)

Au, Lucy January 2009 (has links)
Papua New Guinea has the highest infant and maternal morbidity and mortality rates in the Western Pacific Regions and 50% of hospital admissions are from vaccine preventable diseases. About 85% of 6 million inhabitants live in rural PNG where basic services are lacking or non-existent. Difficulties such as lack of infrastructures like road network and communication, geographical barriers like big mountain ranges, large rivers and swamps, shortage of skilled health professionals and higher concentration of health workers in cities pose great challenges in delivering health services effectively across the country. Telehealth may play an important role in reaching health services to the underserved population in PNG. As part of this study, it is essential to assess the potential of telehealth to enhance the delivery of health services. Specifically, this research aims to report the knowledge, attitudes and skills towards information and communication technology of health care providers in PNG. The study used a cross sectional method of health professionals working at the time of the survey. It collected 174 questionnaires from four hospitals and used SPSS (version17.0) to analyse the data. The results showed that younger male physicians, paramedics, those with gadgets, higher educational qualifications and exposed to ICT resources possess better knowledge and skills than female, older age group and those without gadgets or under exposed to ICT. Currently, the health care professionals in general have leap frogged the technology by focusing on handheld devices such as cell phones rather than landlines. This represents scope for growth and willingness by health workers to adopt and expand telehealth in PNG.
7

Practical Applications for Symbiodinium Grown on Solid Media: Culturing, Fluorometry and Transformations

Soffer, Nitzan 01 January 2009 (has links)
Symbiotic dinoflagellates in the genus Symbiodinium are critical to the success of scleractinian reef corals in shallow tropical seas. These symbionts are commonly isolated from hosts and cultured separately in liquid media (f/2 or ASP8a), but initial isolations can be prone to abundant contaminants that can persist long-term in culture. To help remove these contaminants, I developed a solid growth substrate composed of 1% f/2 medium in agar, supplemented with a variety of antibiotics, to help isolate individual clones and establish new ?axenic? cultures. I found that an antibiotic cocktail of kanamycin (50 µg/mL), ampicillin (100 µg/mL) and streptomycin (50 µg/mL) was the most effective at eliminating visual signs of contamination without apparent harm to a variety of Symbiodinium in culture. Photophysiological measurements of Symbiodinium grown on f/2 agar plates, taken using an Imaging Pulse Amplitude Modulated (I-PAM) fluorometer, were comparable with those grown in liquid f/2, both with and without antibiotics. Eight types of Symbiodinium in clades A-D grown on f/2 agar plates at low irradiance (19-46 µmol photons m-2 s-1) were exposed to higher irradiance conditions (50-90 µmol photons m-2s-1) for 13 days and their photosynthetic efficiencies (Fv/Fm) were compared using the I-PAM. There were significant differences among and within clades, except for two types in clade C (C2 and C3) which did not perform differently from eachother. All types showed reduced Fv/Fm after 12 days in higher light. Type D1a showed high mortality after 13 days of higher light stress. Finally, preliminary work to fluorescently label Symbiodinium determined that available vital stains were not generally practical for symbiosis studies. Attempts to transform Symbiodinium with a variety of plasmids containing fluorescent reporters and/or genes for antibiotic resistance were not successful, but did provide a baseline for future work. In summary, Symbiodinium cultures grown on solid substrates supplemented with antibiotics are useful for: (1) isolating individual cells or clones for subsequent applications and establishing and maintaining ?axenic? cultures that are free of observable contaminants; (2) directly comparing the photophysiology of different cultures using an I-PAM fluorometer; (3) quantifying cells on agar plates using the I-PAM and (4) selecting possible transgenic symbionts for symbiosis studies.

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