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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.
361

Analyse der Erosionsdynamik im Einzugsgebiet des Landwassers (Oberlausitz) – Einfluss auf Gewässergüte und Makrozoobenthosdrift

Kändler, Matthias 12 October 2012 (has links) (PDF)
In der vorliegenden Arbeit werden für ein stark anthropogen beeinflusstes Einzugsgebiet die komplexen Zusammenhänge zwischen Witterung, Landnutzung, Erosion, Gerinneabfluss, Stofffrachten und Makrozoobenthos analysiert. Dafür wurde eine Messstation eingerichtet, an der Fließgeschwindigkeit, Trübung, pH Wert und Leitfähigkeit kontinuierlich gemessen wurden. Mit Hilfe eines durchflussgesteuerten Probennehmers wurden Wasserproben entnommen und im Labor auf verschiedene Inhaltsstoffe (Nährstoffe, Schwermetalle) analysiert sowie die Konzentration von Feinsediment bestimmt. Es konnte eine Beziehung zwischen Trübung und Sedimentkonzentration abgeleitet werden. Die chemischen Analysen zeigten einen komplexen Zusammenhang zwischen der Erosion von landwirtschaftlichen Flächen, dem Stoffeintrag von versiegelten Arealen (Verkehrsflächen, Dächer) aber auch witterungs- und vegetationsbedingte saisonale Effekte. Ein Vergleich der Eigenschaften der Schwebstoffe/Feinsediment im Landwasser mit denen von Ackerboden (Maisfelder) zeigte, dass diese die „chemische Handschrift“ der Ackerböden trugen. Mit Hilfe der Modelle EROSION 3D und ICECREAM wurden die abgetragenen Bodenmengen für das Einzugsgebiet bzw. für ausgewählte Hänge quantifiziert. EROSION 3D überschätzt den Bodenaustrag aus dem Untersuchungsgebiet deutlich. Das Modell ist ungeeignet, um für das Einzugsgebiet reale Abtragswerte mit den zur Verfügung stehenden flächenhaften Eingangsdaten zu berechnen. Bereits für Einzelhänge werden zu große Bodenabträge berechnet. Verstärkend kommt hinzu, dass auf Grund der Modellannahme jeder Partikel, der das Gewässer erreicht auch aus dem Einzugsgebiet heraustransportiert wird. Das Modell kann empfohlen werden, um erosionsgefährdete Flächen auszuweisen. In der Untersuchungsperiode von 2009 bis Juli 2011 wurde an Hand von 57 Driftfängen mit unterschiedlichen hydrologischen Randbedingungen die Wirkung der Fließgeschwindigkeit auf den Übergang benthischer Invertebraten in die freie Welle identifiziert. Aus Uferbereichen gelangen zufällig terrestrische Invertebraten in das Gewässer, deren Anteil sich durch gewässernahen Oberflächenabfluss in Folge von Niederschlagsereignissen erhöht. Die Driftdichte nimmt ab Fließgeschwindigkeiten von 0,3 m/s deutlich zu. Oligochaeta, Cyclopoida und Dipolstraca driften verstärkt bei Fließgeschwindigkeiten >0,6 m/s.
362

Vektoranalytische Beschreibung eines diskret Massiven Systems

Schulze, Rainer W. 12 November 2012 (has links) (PDF)
Diskret Massive Systeme stellen eine hypothetische Alternative zu konventionellen technischen Informationsverarbeitungssystemen dar. Sie sind geeignet, die innere Physik eines dynamischen Prozesses unmittelbar nachzubilden, gewissermaßen “in vitro”. Dementsprechend durchschnittsfremd sind die Einzugsbereiche beider Systeme hinsichtlich ihrer Anwendung. In einem diskret Massiven System bewegen sich von Prozessor zu Prozessor Verkehrsströme, getrieben durch Referenzierungen zwischen den Prozessoren und zwangsgerichtet durch die Topologie des Verbindungsnetzwerkes zwischen den Prozessoren. Die Verarbeitungsleistung des Systems beruht auf der Überlagerung und Verdrängung von Verkehrsströmen. Beschreiben lassen sich diskret Massive Systeme vektoranalytisch als Diffusionsprozess mit Hilfe einer Fokker-Planck-Gleichung. Eine solche Gleichung wird für ein n-dimensionales Raumkontinuum aufgestellt und deren Parameter Diffusionskoeffizient und Beweglichkeitsvektor in einen m-dimensionalen orthonormalen diskreten Raum überführt, dem Aktionsraum eines diskret Massiven Systems. Verkehrsströme eines diskret Massiven Systems werden durch Korpuskelströme entlang von Flusslinien in einem diskreten Aktionsraum nachgebildet. Die beschreibenden Parameter Diffusionskoeffizient und Beweglichkeitsvektor für Korpuskelströme lassen sich durch Zeitmessungen ermitteln.
363

Stability and Non-stationary Characteristics of Queues

Fralix, Brian Haskel 10 January 2007 (has links)
We provide contributions to two classical areas of queueing. The first part of this thesis focuses on finding new conditions for a Markov chain on a general state space to be Harris recurrent, positive Harris recurrent or geometrically ergodic. Most of our results show that establishing each property listed above is equivalent to finding a good enough feasible solution to a particular optimal stopping problem, and they provide a more complete understanding of the role Foster's criterion plays in the theory of Markov chains. The second and third parts of the thesis involve analyzing queues from a transient, or time-dependent perspective. In part two, we are interested in looking at a queueing system from the perspective of a customer that arrives at a fixed time t. Doing this requires us to use tools from Palm theory. From an intuitive standpoint, Palm probabilities provide us with a way of computing probabilities of events, while conditioning on sets of measure zero. Many studies exist in the literature that deal with Palm probabilities for stationary systems, but very few treat the non-stationary case. As an application of our main results, we show that many classical results from queueing (in particular ASTA and Little's law) can be generalized to a time-dependent setting. In part three, we establish a continuity result for what we refer to as jump processes. From a queueing perspective, we basically show that if the primitives and the initial conditions of a sequence of queueing processes converge weakly, then the corresponding queue-length processes converge weakly as well in some sense. Here the notion of convergence used depends on properties of the limiting process, therefore our results generalize classical continuity results that exist in the literature. The way our results can be used to approximate queueing systems is analogous to the way phase-type random variables can be used to approximate other types of random variables.
364

Comparative Analyses For The Central Asian Contribution To Anatolian Gene Pool With Reference To Balkans

Caner Berkman, Ceren 01 September 2006 (has links) (PDF)
Around 1000 ya, Turkic language started to be introduced to Turkey and Azerbaijan (Region of language replacement, RLR) in parallel with the migrations of Turkic speaking nomadic groups from Central Asia. The Central Asian contribution to the RLR was analyzed with four admixture methods considering different evolutionary forces. Furthermore, the association between the Central Asian contribution and the language replacement episode was estimated by comparatively analyzing the Central Asian contribution to RLR and to their non-Turkic speaking neighbors. In the present study, analyses revealed that Chikhi et al.&rsquo / s (2001) method represents the closest estimates to the true Central Asian contributions. Based on this method, it was observed that there were lower male (13%) than female (22%) contributions from Central Asia to Anatolia, with wide ranges of confidence intervals. Lower contribution, with respect to males, is to be explained by homogenization between the males of the Balkans and those of Anatolia. In Azerbaijan this contribution was 18% in females and 32% in males. Moreover, results pointed out that the Central Asian contribution in RLR can not be totally attributed to the language replacement episode because similar, or even higher, Central Asian contributions in northern and southern non-Turkic speaking neighbors were observed. The presence of a 20% or more admixture proportion in the RLR, and the presence of even higher contributions around the region, suggested that language might not be replaced inaccordance with &ldquo / elite dominance model&rdquo / .
365

Generalized Pushover Analysis

Alici, Firat Soner 01 June 2012 (has links) (PDF)
Nonlinear response history analysis is considered as the most accurate analytical tool for estimating seismic response. However, there are several shortcomings in the application of nonlinear response history analysis, resulting from its complexity. Accordingly, simpler approximate nonlinear analysis procedures are preferred in practice. These procedures are called nonlinear static analysis or pushover analysis in general. The recently developed Generalized Pushover Analysis (GPA) is one of them. In this thesis study, GPA is presented and evaluated comparatively with the nonlinear time history analysis and modal pushover analysis. A generalized pushover analysis procedure was developed for estimating the inelastic seismic response of structures under earthquake ground excitations (Sucuoglu and G&uuml / nay, 2011). In this procedure, different load vectors are applied separately to the structure in the incremental form until the predefined seismic demand is obtained for each force vector. These force vectors are named as generalized force vectors. A generalized force vector is a combination of modal forces, and simulates the instantaneous force distribution on the system when a given response parameter reaches its maximum value during the dynamic response. In this method, the maximum interstory drift parameters are selected as target demand parameters and used for the derivation of generalized force vectors. The maximum value of any other response parameter is then obtained from the analysis results of each generalized force vector. In this way, this procedure does do not suffer from the statistical combination of inelastic modal responses. It is further shown in this study that the results obtained by using the mean spectrum of a set of ground motions are almost identical to the mean of the results obtained from separate generalized pushover analyses under each ground motion in the set. These results are also very close to the mean results of nonlinear response history analyses. A practical implementation of the proposed generalized pushover analysis is also developed in this thesis study where the number of pushovers is reduced in view of the number of significant modes contributing to seismic response. It has been demonstrated that the reduced generalized pushover analysis is equally successful in estimating maximum member deformations and member forces as the full GPA under a ground excitation, and sufficiently accurate with reference to nonlinear response history analysis.
366

The preparation and properties of the pH-ISFET with amorphous PbTiO3 membrane by the sol-gel technique

Lu, Chun-Te 04 July 2001 (has links)
Ion-sensitive field effect transistors (ISFET's) have many advantages than the conventional ion selective electrode. Small size, fast response and compatible with conventional IC technologies were the most important advantages. The general structure of ISFET was the same with MOSFET, but the main difference is that the metal gate in MOSFET was replaced by reference electrode/electrolyte/insulator(ionic sensor membrane) structure in ISFET. The insulator surface will suffer the change of potential as the is sample immersed into electrolyte, by which, we can measure the pH or other ionic concentration. In this thesis the amorphous lead titanate (a-PbTiO3) thin film was prepared by sol-gel method to be the sensor gate of ISFET. The lead titanate thin films were deposited on SiO2(1000Å)/p-Si substrates, and the EIS structure was obtained. The flat-band voltage(£GVBF) can be shifted by C-V measurement. The optimum conditions were found that the firing temperature was about 4000C and thin film thickness was about 0.5
367

Study on the pH-sensing characteristics of the hydrogen ion-sensitive field-effect transistors with sol-gel-derived lead titanate series gate

Jan, Shiun-Sheng 15 November 2002 (has links)
The sol-gel-derived lead titanate (PbTiO3) membrane has been successfully applied as a novel pH-sensing layer to form the PbTiO3 gate ISFET (ion-sensitive field-effect transistor). There exhibit the excellent quasi-Nernstian response of 55-58 mV/pH, good surface adsorption and anticorrosion characteristics via the capacitance- voltage measurement of the electrolyte-insulator-semiconductor structure. At a specific pH concentration, the output and transfer characteristics of the PbTiO3 gate ISFET are very similar to the behaviours of MOSFETs (metal-oxide-semiconductor field-effect transistors), and the pH-ISFET model can be derived by the modified MOSFET model. As it operated in the nonsaturation region, there exhibits a linear pH response of about 55-58 mV/pH. Simultaneously, there exhibit the stable response time of 2-4 minutes, the drift of 0.5-1 mV/h, the hysteresis of 3-5 mV and the reduction rate of about ¡V10 mV/pH-day. On the other hand, as it operated in the saturation region, the pH responses and linearity can be controlled by adjusting the VGS values, e.g. the absolute pH response of 4.2, 24.8 and 31.3 uA/pH and the correlation coefficients of 0.9491, 0.9995 and 0.9996 at VGS= 1, 3 and 5 V can be obtained, respectively. Besides, the PbTiO3 gate ISFET has been modified by doping the Mg2+ and La3+ impurities into the PbTiO3 membrane. As a result, the former is a great benefit to improve the pH-sensing characteristics, which exhibits the pH response of 58-59 mV/pH, the drift of below 0.4 mV/h, the hysteresis of 1-3 mV and the reduction rate of -0.2 mV/pH-day. Finally, a digital pH meter has been successfully developed.
368

Molecular systematics and phylogeography of the dusky dolphin (Lagenorhynchus obscurus) derived from nuclear and mitochondrial loci

Harlin, April Dawn 12 April 2006 (has links)
This study presents evidence from mitochondrial and nuclear loci that there is genetic divergence among and within geographic populations of Lagenorhynchus obscurus. The effect of seasonal variation on the genetic structure within New Zealand was examined with mitochondrial DNA control region sequences from 4 localities. Analysis of nested haplotype clades indicated genetic fragmentation and at least 1 historical population expansion within New Zealand. AMOVA and Fst values from nuclear and mitochondrial DNA sequences suggested significant divergence between New Zealand, South Africa, Argentina, and Peru. Dispersal via the west-wind drift was not supported by patterns of population structure among regions. Alternatively, these data support reciprocal exchange among all four regions with 100% posterior probability for a root of origin in the Indian/Atlantic Oceans. The degree of divergence between Peru and other regions indicates the isolation of Peruvian stock is temporally correlated with the constriction of Drake’s passage in the Plio-Pleistocene. There is evidence that the Plio-Pliestocene paleoceanography of the Indian and Southern Atlantic Oceans influenced phylogeography with shifts of temperate sea surface temperatures northward ~5º of latitude, disrupting the dispersal corridor between New Zealand and Atlantic populations. A preference for temperate waters along continental shelves is proposed as an explanation for lack of contemporary genetic exchange among regions. This study supports the polyphyly of the genus Lagenorhynchus. North Atlantic species form a monophyletic Lagenorhynchus. In the Southern Hemisphere, L. australis/L. cruciger and L. obliquidens/L. obscurus do not form a monophyletic group. I discuss the taxonomic implications and propose taxonomic revision of the genus based on these results. Measures of character interaction indicate that combined evidence from nuclear and mitochondrial genes provide better phylogenetic resolution among delphinid lineages than any data partition independently, despite some indications of conflict among mitochondrial and nuclear data.
369

Insider trading on the Stockholm Stock Exchange : Non reported insider trading prior to profit warnings

Lindén, Patrik, Lejdelin, Martin January 2007 (has links)
<p>Background:</p><p>Studying insider trading is difficult due to its sensitive and delicate nature. Therefore it is hard to gauge the extent of such activities. This problem has resulted in a fierce debate whether it should be prohibited or not. Using a method where the effect on monopolistic information usage can be isolated insider trading can be monitored. Such an event is a profit warning.</p><p>Purpose:</p><p>This paper examines whether insider trading exist for companies</p><p>making a profit warning between year 2003 and 2007 on the Stockholm</p><p>Stock Exchange. Furthermore the aim with the study is to contribute</p><p>to the debate on the insider trading legislation.</p><p>Method:</p><p>The study’s purpose is achieved through an event study studying the</p><p>cumulative abnormal return as well as average daily returns during</p><p>the thirty days preceding the warning for a sample of thirty companies.</p><p>Since profit warnings should be completely random and as such</p><p>almost impossible for the market to know in advance, a significant</p><p>abnormal return can only be explained with insider trading. The abnormal returns were calculated using the Capital Asset Pricing Model</p><p>since it is the most widely used model.</p><p>Conclusion:</p><p>For the chosen time frame, when testing on a 95% significance level,</p><p>the study found a significant abnormal return during the last 10 days</p><p>of the event window but not for the entire period of thirty days. The</p><p>daily average return for the thirty companies were significant for six</p><p>of the thirty days within the event window. Two of them were included</p><p>in the last ten day period with a confirmed significant abnormal</p><p>return which might suggest that on average insider trading tend</p><p>to occur during these days. The other four was discarded due to</p><p>sample issues. Since the study was limited to a period of four years</p><p>extending the results to a period other than tested should be made</p><p>with great care since conditions may differ over time. Concerning the</p><p>current debate on the insider legislation, the findings can be used by</p><p>both sides. Either to argue for a strengthening of the law or to question its existence.</p>
370

Upphandling av vinterväghållning

Zetterström, Carina, Isaksson, Anna January 2006 (has links)
<p>This report was undertaken at the request of the Management and maintenance department of Swedish National Road Authority (Vägverket Region Sydöst) in Jönköping.</p><p>In 1992, the management and maintenance of Swedish roads were laid out on external constructors. When putting out a tender for the work, the foundation is from a national set of rules which are in constant change. This report is limited to winter road upkeep.</p><p>The trend in the invitation for tenders is that it is moving from the more conventional executional demands towards the less controlling demands. The downside of functional, less controlling demands is that it is difficult to articulate how to measure them. The order authority therefore has to find ways to make sure to get what has been paid for.</p><p>In connection to the invitation for tender of winter road upkeep for 2005, the new set of rules, ATB Vinter 2003 was deployed.</p><p>The main purpose of this thesis is to see which the big changes in the set of rules are and how these changes affect the organisation and activities of the constructor.</p><p>It is also studied how the changes in execution is perceived by road users and how it affects the possibilities of the constructor to come as a newcomer to a new area of administration.</p><p>Interviews and examination of sets of rules has led to a list of a number of changes that the constructors feel affect their work in any sense.</p><p>Views from road users that have come in to the order authority have been scrutinized to see how they have experienced the change. When selecting which areas of administration to examine, care was taken to ensure that one was where the same constructor secured a renewed contract for the area over the gap of changing rules and the other one was area where the constructor was a newcomer.</p><p>The result shows a number of changes and how these affect both the constructors and the road users.</p><p>The report describes how winter road upkeep is maintained in the south of Sweden and the cooperation between buyer and constructor.</p>

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