• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 332
  • 148
  • 72
  • 62
  • 40
  • 23
  • 21
  • 8
  • 7
  • 7
  • 7
  • 5
  • 5
  • 4
  • 3
  • Tagged with
  • 846
  • 139
  • 126
  • 68
  • 68
  • 66
  • 57
  • 51
  • 50
  • 50
  • 48
  • 48
  • 46
  • 45
  • 42
  • 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.
221

Asymptotische Resultate über Lokalzeiten von Irrfahrten im Zd

Becker, Mathias 15 January 2014 (has links) (PDF)
Gegenstand der vorliegenden Dissertation ist das Verhalten sogenannter Selbstüberschneidungslokalzeiten $\\|\\ell_t\\|_p^p$ einer zeitstetigen Irrfahrt $(S_r)_r$ auf dem $d$-dimensionalen Gitter $\\Z^d$. Dabei ist für $p>1$ die Funktion $\\ell_t$ definiert durch $$ \\ell_t(z):=\\int_{0}^{t}\\1_{\\{S_r=z\\}}\\,\\d r\\nonumber $$ und bezeichnet die Aufenthaltsdauer der Irrfahrt bis zum Zeitpunkt $t\\in(0,\\infty)$ im Punkt $z\\in\\Z^d$. Ziel ist es, ein Prinzip großer Abweichungen zu entwickeln, d.h. das Hauptaugenmerk liegt auf dem asymptotischen Verhalten der Wahrscheinlichkeit, dass die Selbstüberschneidungslokalzeiten von ihrem Erwartungswert in erheblichem Maße nach oben abweichen. Mit anderen Worten; es soll das asymptotische Verhalten von $$ \\log\\P(\\|\\ell_t\\|_p^p\\geq r^p_t) $$ genau bestimmt werden, wobei $r_t^p\\in(0,\\infty)$ schneller als der Erwartungswert $\\E[\\|\\ell_t\\|_p^p]$ gegen unendlich streben soll. Dieses Verhalten kann dabei durch $t$, $r_t$ und eine gewisse Variationsformel beschrieben werden. Es wird sich herausstellen, dass es zwei Fälle zu betrachten gilt, in denen sich das probabilistisch beste Verhalten stark unterscheidet; die genaue Position des Phasenübergangs hängt dabei von den Parametern $p$ und $d$ ab. Im Vorgriff auf die Resultate kann man festhalten, dass die nötigen Selbstüberschneidungen in kleinen Dimensionen (im sogenannten subkritischen Fall) über einen großen Bereich erfolgen, aufgrund dessen bei der mathematischen Modellierung eine Reskalierung erforderlich ist. In hohen Dimensionen (dem sogenannten superkritischen Fall) ist dies nicht nötig, da die erforderlichen Selbstüberschneidungen innerhalb eines begrenzten Intervalles erfolgen. Das Interesse an der Untersuchung entstand unter anderem aus der Verbindung zu Modellen der statistischen Mechanik (parabolisches Anderson Modell) und zur Variationsanalysis. In der Vergangenheit wurde eine Vielzahl an Methoden benutzt, um dieses Problem zu lösen. In der vorliegenden Dissertation soll die sogenannte Momentenmethode bestmöglich ausgereizt werden und es wird gezeigt, welche Ergebnisse damit möglich sind.
222

Contribution des Smart Grids à la transition énergétique : évaluation dans des scénarios long terme

Bouckaert, Stéphanie 19 December 2013 (has links) (PDF)
Dans le cadre des débats sur la transition énergétique, l'implémentation des Smart Grids est avancée comme une part de la solution pour répondre à la fois aux questions climatiques et aux enjeux énergétiques. Les modèles de prospective constituent des outils d'aide à la décision permettant d'orienter les trajectoires énergétiques afin de satisfaire aux futures demandes en tenant compte de contraintes environnementales et techniques. Ces modèles historiques, caractérisés principalement par l'adéquation de l'offre à la demande doivent désormais évoluer pour intégrer les développements futurs attendus du système électrique. Dans ce travail, nous avons implémenté dans une approche de long terme différentes fonctionnalités propres aux Smart Grids (gestion de la demande, stockage, énergies renouvelables). Cette approche nous permet d'évaluer les bénéfices liés à chacune d'entre elles séparément, ou bien conjointement au travers de bouquets de solutions, tenant ainsi compte des possibles interactions entre ces fonctionnalités. Nous avons également intégré un indicateur reflétant le niveau de fiabilité du système électrique dans notre modèle. Ce paramètre supplémentaire permet de contraindre les futurs systèmes électriques afin qu'ils garantissent un niveau de service en terme de fourniture électrique identique à celui des systèmes existants. Cette étude est illustrée par le cas de l'île de la Réunion, qui s'est donné pour objectif de produire d'ici 2030 son électricité à partir de sources uniquement renouvelables, et pour qui les fonctionnalités de Smart Grids pourraient constituer un levier intéressant.
223

“Dead. He is Dead. God blesses America” : Den Amerikanska pressens gestaltning av kriget mot terrorism kring Usama bin Ladins död / “Dead. He is Dead. God blesses America” : Framing of the War on Terror in the American press surrounding the death of Osama bin Laden

Adrian, Carl, Holm, Jonas January 2013 (has links)
Almost 10 years after the attack on World Trade Center Sept. 11 2001, Osama bin Laden was shot and killed on May 2 2011 in Pakistan. How was this event framed by the media with regards to the global war on terror? This study compares two different American newspapers – the New York Times and the New York Daily News – and how they framed the war on terrorism in the Middle East from May 2 to May 15 2011. By analyzing the framing in a perspective of the four functions of framing theory: define problems, diagnose causes, make moral judgments and suggest remedies, we found considerable differences in each papers frames. Through a qualitative text analysis of the opinion pages in these two newspapers, using three themes as a base, we found a number of differences. While the New York Times contained a form of open discussion about problems and remedies, New York Daily News takes an emotional and moral approach. These differences in content may affect the opinions of the readers. We speculate that the more open and suggestive nature of the New York Times, also opens the minds of the readers enabling them to form opinions in a liberated sense. Thus the more closed, emotional and moral nature of the New York Daily News may have greater impact on an individual’s ability to form its own opinions and moral values.
224

Experimental and Computational Study of Flame Inhibition Mechanisms of Halogenated Compounds in C1-C3 Alkanes Flames

Osorio Amado, Carmen H 16 December 2013 (has links)
After the restriction of different halogenated fire suppressants by the Montreal Protocol, there is an urgent need to identify environmentally friendlier alternatives. In particular, several efforts have been conducted to find substitutes of Halon 1301 (CF_(3)Br) which was considered the best in its class, not only because of its superior extinguishing performance, but also due to its relatively low toxicity. Different options have been proposed over the last decade. However, no single compound has been found to meet all of the exigent criteria. Further progress in this research requires fundamental combustion knowledge that can help us understand the unique performance of Halon 1301, to prevent this search from becoming a tedious trial-and-error process. To this end, the present work aids in the search of fire suppressants alternatives by improving the flame inhibition mechanism understanding, starting with CF_(3)Br, which serves as a benchmark for new fire suppressants. Then, a case study of two of the most currently used fire suppressants, C_(2)HF_(5) (HFC-125) and C_(2)HF_(7) (HFC-227), is presented and compared with CF_(3)Br performance. For these analyses, a systematic analytical methodology was used to examine the effect of fire suppressants on ignition and laminar flame propagation of C_(1)-C_(3) alkanes premixed mixtures, as good representatives of flammable gas fires (Class B fires). This methodology integrates model formulations and experimental designs in order to examine both chemical kinetics and thermal effects on fire suppressants at different stoichiometric conditions. Modeling predictions were based on a detailed chemical kinetics mechanism which was assembled from a new, well-studied H_(2), C_(0)–C_(5) hydrocarbon mechanism from NUI Galway and recent CF_(3)Br and HFC fire suppressant chemistry from NIST. Experimental study involved the use of a shock tube (for ignition analysis) and a freely expanding flame speed bomb (for laminar flame speed analysis). Most of the experimental data provided in this work are the first measurements of their kind for the compounds and mixtures explored in this thesis. These measurements are extremely valuable since they can be used as a metric for model validation which represents one of the objectives of this work. Current analyses indicate that the combustion properties of halogenated compounds cannot be generalized and depends on different factors. On one hand, the presented results showed that all the tested fire suppressants can decrease the laminar flame speed of the examined C_(1)-C_(3)alkanes premixed flames; however, in some cases they can act as ignition promoters. In order to understand these behaviors, sensitivity analyses were conducted showing that halogenated species, resulting from the fire suppressants decomposition, can participate in both promoting and inhibiting reactions that compete to give a net effect. Identification of the key reaction responsible for such effects was conducted. Then, improvements on the fire suppressant chemistry can be done by modifying the corresponding Arrhenius parameters of such important reactions. This work not only provides fundamental knowledge of halogenated flame inhibition mechanisms, but also serves as the basis for more accurate chemical kinetics mechanisms that can be used for better predictions over a wide range of conditions.
225

Access block experienced by a general internal medicine population: factors and outcomes

Wolodko, Lesley Unknown Date
No description available.
226

THE IMPACT OF DUAL CHAMBER COW WATERBEDS AS A FREESTALL BASE

Wadsworth, Barbara Alice 01 January 2014 (has links)
The objectives of this research were to compare lying time, milk yield, rumination time, hock score, stall cleanliness, and stall temperature for 97 cows (Holsteins (n = 71), Jerseys (n = 10), and crossbreds (n = 16)) housed on Dual Chamber Cow Waterbeds™ (DCCW, Advanced Comfort Technology, Reedsburg, WI) or conventional rubber mattresses (MAT). This study was conducted at the University of Kentucky Coldstream Research Dairy Farm from January 18, 2012 to May 3, 2013. Lying times were longer (P < 0.01) for cows housed on the DCCW (10:32 ± 0:13) compared to cows housed on the MAT (9:47 ± 0:15). Milk yield was not different (P ≥ 0.05) between cows housed on the DCCW or MAT. Rumination times were greater (P = 0.03) for cows housed on MAT (6:44 ± 0:08) compared to cows housed on DCCW (6:29 ± 0:08). Hock scores were lesser (P = 0.02) for cows housed on DCCW (1.86 ± 0.03) compared to cows housed on MAT (1.97 ± 0.04). Stall cleanliness was not different (P ≥ 0.05) between the DCCW and the MAT. The DCCW stall temperature was warmer (P < 0.01) (13.29 ± 0.21 ⁰C) than the MAT (10.52 ± 0.21 ⁰C).
227

Characterisation of a New Type of Solid Organic Scintillator for neutron-gamma Discrimination using Pulse-Shape DiscriminationTechniques

Nishada, Qadir January 2014 (has links)
In this report the neutron-gamma discrimination capabilities of the new type of solid organic scintillator, EJ-299-33, was investigated using several pulse-shape discrimination (PSD) techniques. Among others, the analog zero-crossing method andthe digital charge-comparison and integrated-rise-time method were tested. The parameters of the digital PSD methods were optimised individually and the figure-of-merit was measured for each method and compared in different energy windows. The photoelectron yield of the setup was measured using two different photomultiplier tubes (PMT), a 3 inch diameter ET 9821 and a 5 inch diameter ET 9390KB. The highest photoelectron yield was measured with the ET 9390KB, which was the PMT used for the neutron-gamma discrimination capability measurements. In this work, four decay constants were found for the scintillator decay times. These were found by fitting average neutron and gamma-ray waveforms with the convolution of severeal exponential functions, that describes the light emission intensity of the scintillator, with an approximation of the PMT response function. Thebest agreement was found for the assumption that the scintillator light emission intensity is governed by four decay constants. The intensity of the two slowest components contain information about the incident particle.
228

A content analysis of newspaper coverage on the blockbuster drug Prozac

Puls, Carole Aimee Witsken January 2008 (has links)
This study analyzed news coverage from the Indianapolis Star and The New York Times about the blockbuster drug Prozac® from the day it was approved on Dec. 29, 1987, until Dec. 31, 2006, to gain insights about whether the tone and prominence of news stories about Prozac changed over the duration of its 20 year lifecycle.A content analysis was used to evaluate whether stories were more favorable in tone during the first phase of Prozac's lifecycle, whether the tone of those stories became more negative as time passed, and, if it did, during which phase of Prozac's lifecycle that change in tone occurred.The findings from this study can assist public relations practitioners - particularly those who work in the pharmaceutical industry - in developing proactive and strategic media relations plans for consumer products such as prescription drugs and establishing more appropriate expectations and projected metrics. / Department of Journalism
229

A historical review of the New York times' coverage of Susan B. Anthony's participation in the woman's suffrage movement

Woodrow, Deborah S. January 1975 (has links)
This thesis examined the news coverage and editorial coverage the New York Times gave Susan B. Anthony’s participation in the women’s suffrage movement from the time Miss Anthony joined the movement in September 1852 until her death in March 1906. Using various books on Miss Anthony as well as the New York Times index, a chronological list of events and activities involving Miss Anthony’s participation in the woman’s suffrage movement was complied. Pages of the New York Times then were examined on the dates and near the dates of Miss Anthony’s activities to learn what coverage the newspaper had given her or the movement.The study showed that when the woman’s suffrage movement began in the early 1800s, women had few of the rights they enjoy today. Society of the time believed a woman’s place was in the home and that only man, as head of the household and chief breadwinner, should enjoy the right of suffrage. However, people who supported the woman’s suffrage movement believed women should enjoy the same employment opportunities and wages men of that day enjoyed and saw the ballot as the women could achieve those opportunities.Having shown the society of the early 1800s as well as the reasons for the woman's suffrage movement, the thesis focused on Miss Anthony's activities in the movement to show the coverage the New York Times gave her and the movement both news-wise and editorially throughout her life. The thesis found the New York Times covered her activities and those of the movement factually, based on the historical books written about her life and activities. However, the study found the newspaper's editorial opposition to the movement lacked the facts to support its emotional, and often illogical, feelings against the movement. Only when Miss Anthony was found guilty of voting did the New York Times stand on firm ground in opposition to her actions because it presented facts based on the United States Constitution to support its statements.The thesis concluded the New York Times reported its news stories factually and accurately, but used emotional appeals which lacked facts to support its opposition to the woman's suffrage movement. The thesis also concluded the New York Times reflected the society it served, a society that believed woman belonged in the home instead of out in a man's world, demanding the ballot in order to achieve equal rights with man.
230

Large Deviations for Brownian Intersection Measures

Mukherjee, Chiranjib 18 October 2011 (has links) (PDF)
We consider p independent Brownian motions in ℝd. We assume that p ≥ 2 and p(d- 2) < d. Let ℓt denote the intersection measure of the p paths by time t, i.e., the random measure on ℝd that assigns to any measurable set A ⊂ ℝd the amount of intersection local time of the motions spent in A by time t. Earlier results of Chen derived the logarithmic asymptotics of the upper tails of the total mass ℓt(ℝd) as t →∞. In this paper, we derive a large-deviation principle for the normalised intersection measure t-pℓt on the set of positive measures on some open bounded set B ⊂ ℝd as t →∞ before exiting B. The rate function is explicit and gives some rigorous meaning, in this asymptotic regime, to the understanding that the intersection measure is the pointwise product of the densities of the normalised occupation times measures of the p motions. Our proof makes the classical Donsker-Varadhan principle for the latter applicable to the intersection measure. A second version of our principle is proved for the motions observed until the individual exit times from B, conditional on a large total mass in some compact set U ⊂ B. This extends earlier studies on the intersection measure by König and Mörters.

Page generated in 0.0388 seconds