• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 326
  • 173
  • 73
  • 36
  • 33
  • 23
  • 8
  • 8
  • 7
  • 7
  • 4
  • 4
  • 4
  • 3
  • 3
  • Tagged with
  • 834
  • 142
  • 98
  • 96
  • 95
  • 74
  • 74
  • 63
  • 63
  • 55
  • 54
  • 53
  • 53
  • 52
  • 49
  • 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.
351

Methods of capturing the potential benefits of the Aswan High Dam in Egypt, U A R

Habib, Salem Nasr 08 1900 (has links)
No description available.
352

Können Betriebsauslässe zur Hochwasserentlastung von Talsperren herangezogen werden?

Pohl, Reinhard 17 March 2015 (has links) (PDF)
Veränderte Randbedingungen erfordern modifizierte Betriebsregeln. Während die güteorientierte Bewirtschaftung von Stauräumen in der Vergangenheit hauptsächlich bei der langfristigen Bewirtschaftung eine Rolle spielte, gewinnt sie in jüngerer Zeit immer mehr auch bei der kurzfristigen Abflusssteuerung als Vorentlastung und während der Hochwasserereignisse an Bedeutung. Dabei soll vor allem die Entlastung aus Horizonten mit geringerer Wasserqualität ermöglicht werden. Gleichzeitig kann es notwendig werden, im Hochwasserfall insgesamt mehr vorzuentlasten und die Entnahmeeinrichtungen mit einzubeziehen. Der vorliegende Beitrag beschäftigt sich mit den diesbezüglichen Möglichkeiten bei Nutzung vorhandener Entnahmeeinrichtungen und den Anforderungen an bauliche Ergänzungen. Es werden Grundsätze für die Planung, die Berechnung, den Betrieb und die Überwachung sowie Beispiele aus hydraulischer Sicht besprochen.
353

Risiken, die von Stauanlagen ausgehen

Pohl, Reinhard, Bornschein, Antje 17 March 2015 (has links) (PDF)
Eigentümer und Betreiber von Anlgen mit einem großen Gefahrenpotential sind gehalten, den zuständigen Behörden Auskunft über mögliche Folgen eines Störfalles zu erteilen. Für den unwahrscheinlichen Fall des Bruches eines Absperrrbauwerkes können diesbezügliche Informationen erarbeitet werden.
354

Dam break during the flood in Saxony/Germany in August 2002

Bornschein, Antje, Pohl, Reinhard 10 February 2015 (has links) (PDF)
The heavy rainfall event in August 2002 in Saxony/Germany caused the break of a flood retaining basin in a valley of the Erzgebirge Mountains. The rainfall event with ists hyrologic characteristics and dam break event were analysed and an outflow hydrograph was determing. The propagation of the dam break flood wave in the valleyas of the Briesnitz and Müglitz Rivers has been simulated. Calculated values were compared with some observed data.
355

TRIBUTARY RESPONSE TO THE LAKE LIVINGSTON IMPOUNDMENT -- LOWER TRINITY RIVER, TEXAS

Musselman, Zachary Allen 01 January 2006 (has links)
The purpose of this study is to describe and explain tributary changes within the lower Trinity River basin, Texas, downstream of Livingston Dam. Within southeastern Texas, an opportunistic geomorphic experiment arose when the Trinity River was impounded. The dam represents a marked moment and place of a system perturbation. Geomorphological effects of the lower Trinity River tributaries were investigated through five different types of data: analysis of published discharge and sediment load data, examination of alluvium, planform change as measured from aerial photographs, resurveys of bridge cross-sections, and field mapping of geomorphic indicators of change. Since closure, Lake Livingston has reduced sediment supply while minimally affecting the discharge regime. Channel scour is evident for about 60 km downstream. All the tributaries studied are located within this reach. Currently, there is no model that directly addresses the morphological response of a tributary streams confluence downstream of a dam. Therefore, the Confluence Effects Model is developed to predict the resulting geomorphological impacts within a tributary streams mouth with varying changes in trunk stream discharge and channel morphology. When applied to two confluences of the lower Trinity River, the Confluence Effects Model successfully predicts the resulting geomorphological changes. Within the lower Trinity River basin, the tributaries are reacting in a nonlinear and complex manner. Delayed or lagged responses are illustrated through sediment budgets for two tributaries which suggest a large amount of sediment is in storage within the tributary basins. Applying the unstable hydraulic geometry model, thirteen qualitatively different modes of adjustment with respect to increases, decreases or lack of change in width, depth, slope and roughness were observed within the tributary systems. The nonlinear and complex reactions of the tributary systems mask the effects of the impoundment beyond the confluences with the Trinity. The geomorphic characteristics of the tributaries are largely dominated by Holocene sea level change and the response to extreme events, such that dam effects become relatively localized. While this study considered a coastal plain fluvial system perturbed by human modifications, other earth surface systems may draw comparisons between emergent responses, response times and landscape sensitivity to a disturbance within a system.
356

Fotogrammetrisk analys av kornstorleksfördelningeni erosionsskydd vid kraftverksdammar / Photogrammetric analysis of the grain size distributionof erosion protection at hydropower dams

Bäcklund, Annika January 2014 (has links)
This master thesis was made to investigate the possibilities of using the Matlab-basedsoftware Basegrain to determine grain size distributions of erosion protections onhydropower dams. Basegrain is a photogrammetric tool developed to generate grainsize distributions and other information about coarse flood sediments by analyzing adigital photo of the stone bed. The investigation was made by validating the ability forBasegrain to assess grain size distributions of various materials smaller than the blocksused in an erosion protection by comparing sieving results or manual measurementswith the results obtained by the program. A statistical comparison was then made bycomparing the results from sieving and the program. The possibilities of using thesame method on existing hydropower dams were then investigated by determiningwhether the method was practically viable or not.The results showed that Basegrain generated grain size distributions for coarse gravelthat were very close to the sieving results. It also provided grain size distributions forlarger fractions of stones quite close to the results made by measuring the diameterof the stones by hand. The results also showed it was possible to use the samemethod on existing erosion protections on hydropower dams and obtain grain sizedistributions.
357

”One missed pass means a non-perfect game” : Perfektionism och prestationsångest inom damelitfotboll

Mikola, Noora, Tegnestrand, Tobias January 2014 (has links)
Sammanfattning Syfte och frågeställningar Syftet med studien var att undersöka perfektionism och prestationsångest relaterat till varandra samt till ålder och erfarenhet hos kvinnliga elitfotbollsspelare. Hur samvarierar ålder och antal år på elitnivå med typen av perfektionism och graden av prestationsångest? Hur vanligt förekommande är adaptiv och maladaptiv perfektionism samt prestationsångest hos kvinnliga elitfotbollsspelare? Samvarierar typen av perfektionism med graden av prestationsångest? Metod I studien medverkade 93 spelare från tre lag i Damallsvenskan, ett lag i Elitettan och åtta lag i Naisten Liiga.  En webbaserad enkät som innefattar egenkonstruerade bakgrundsfrågor samt två mätinstrument: Sports Multidimensional Perfectionism Scale-2 och Sports Competition Anxiety Test användes. Data analyserades med hjälp av Chi²-test samt Spearmans korrelationstest. Resultat Ålder och antal år på elitnivå visade inga signifikanta samband med perfektionism eller med prestationsångest. Det visade sig att 18 % av spelarna inte kunde definieras som perfektionister och att 82 % av spelarna kunde definieras som perfektionister. Av de spelare som kunde definieras som perfektionister, hade 81 % adaptiv perfektionism. Av spelarna hade 19 % låg prestationsångest, 58 % medelhög prestationsångest och 23 % hög prestationsångest. Inget statistiskt signifikant samband hittades mellan perfektionism och prestationsångest (r=-.097, p=.381). En måttlig korrelation hittades mellan två maladaptiva dimensioner av perfektionism och prestationsångest. De dimensioner som korrelerade måttligt var Concern Over Mistakes (r=.355) och Doubts About Actions (r=.462). Slutsats Varken perfektionism eller prestationsångest verkade vara vanligt förekommande hos kvinnliga elitfotbollspelare. Dessa två aspekter verkade inte heller samvariera med ålder eller antal år på elitnivå.
358

Control Of Groundwater By Underground Dams

Yilmaz, Metin 01 November 2003 (has links) (PDF)
In this study underground dams are briefly described and detailed information about the design and construction aspects is provided. Since the material, of which dam wall is composed, is the main variable influencing the groundwater behavior, various types of dam wall are discussed. The use and usefulness of the underground dams as a means of sustainable development, and their performance in the management of groundwater resources are analyzed with the help of two example studies. In the first example a hypothetical idealized aquifer is considered, while in the second one, a real aquifer is selected. For the performance evaluation, and for the analysis of the impact of the underground dams on the groundwater behavior, numerical simulation is opted. For that purpose, a well-known computer code, MODFLOW, A Modular Three-Dimensional Finite Difference Groundwater Flow Model of U.S. Geological Survey, (McDonald and Harbaugh, 1988) is used.
359

Ilisu Dam And Hepp, Investigation Of Alternative Solutions

Yalcin, Emrah 01 October 2010 (has links) (PDF)
This study is an assessment of a hydraulic solution not only rescues Hasankeyf with countless ancient monuments from inundation but also supplies the foreseen energy production of the Ilisu Dam and HEPP Project. An alternative composed of five dams on the Tigris River and its branches was developed as a result of the conducted hydro-meteorological, water potential, flood analysis and optimization studies considering the topographical and geological characteristics of the proposed dam locations. While there is a 27 percent decrease in the overall reservoir area compared to the existing project, 4426.1 hm3 of water can be stored in these dams with a fill volume of 14.8 hm3. Over this storage, determined according to the maximum water levels designated by considering the upstream schemes developed by General Directorate of State Hydraulic Works (DSI), General Directorate of Electrical Power Resources Survey and Development Administration (EIE) and incorporated companies according to Law No.4628, a volume of 3634.4 hm3 can be used as active storage. In the fully developed upstream stage, according to the conducted consecutive operation studies, while the existing project has an energy production capacity of 3094.3 GWh/year, the proposed project is capable of providing 3139.1 GWh/year with a smaller installed power although there is a slight decrease in the produced firm energy.
360

The effects of artificial watering points on the distribution and abundance of avifauna in an arid and semi-arid mallee environment

Harrington, Rhidian January 2002 (has links) (PDF)
The role of artificial watering points in the avifaunal dynamics of the semi-arid mallee woodlands of southeast Australia was examined. Species richness and abundance were monitored throughout the year at different distances from water to determine how birds were distributed around water points and how this changed in relation to environmental factors such as climate. Vegetation attributes were also measured to determine which factors explained patterns in the avifauna with distance from water, and also to allow a description of the vegetation in relation to the water points. Water points were monitored throughout the year to determine which species were utilising them, under which environmental circumstances and for what purposes. Knowledge of the water utilisation behaviour of individual bird species allowed some explanation of their distribution patterns, as well as an ability to predict the likely effects of water point closure on those bird species. The closure of two water points during the study allowed an assessment of the immediate effects of water point closure on avifauna (For complete abstract open document)

Page generated in 0.4334 seconds