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Mulhearn, Michael James. "A direct search for Dirac magnetic monopoles." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32420.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, June 2005.Includes bibliographical references (p. 159-164).
Magnetic monopoles are highly ionizing and curve in the direction of the magnetic field. A new dedicated magnetic monopole trigger at CDF, which requires large light pulses in the scintillators of the time-of-flight system, remains highly efficient to monopoles while consuming a tiny fraction of the available trigger bandwidth. A specialized offline reconstruction checks the central drift chamber for large dE/dx tracks which do not curve in the plane perpendicular to the magnetic field. We observed zero monopole candidate events in 35.7 pb⁻¹ of proton-antiproton collisions at ... = 1.96 TeV. This implies a monopole production cross section limit [sigma] < 0.2 pb for monopoles with mass between 100 and 700 GeV, and, for a Drell-Yan like pair production mechanism, a mass limit m > 360 GeV.
by Michael James Mulhearn.
Ph.D.
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Morgan, Eirwen. "Direct search for Salmonella serotype typhimurium gut invasins." Thesis, University of Birmingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364990.
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Szeto, Raymond W. L. (Raymond Wen Li) 1977. "Clamping-simplex methods : improved direct search simplex algorithms." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/86829.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.Includes bibliographical references (leaf 66).
by Raymond W.L. Szeto.
M.Eng.
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Navrer-Agasson, Anyssa. "Direct dark matter search with the DarkSide Experiment." Thesis, Université de Paris (2019-....), 2019. https://theses.md.univ-paris-diderot.fr/NAVRER-AGASSON_Anyssa_va2.pdf.
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L'existence de la matière noire est connue en raison de ses effets gravitationnels et, bien que sa nature reste inconnue, un des candidats principaux est une particule massive interagissant faiblement (WIMP) ayant une masse de l'ordre de 100 GeV/c2 et un couplage avec la matière ordinaire à ou en dessous de l'échelle faible. Dans ce contexte, DarkSide-50 cherche à observer des collisions WIMP-nucléon dans une chambre de projection temporelle à double phase d'argon liquide située dans le sous-sol du Laboratoire National du Gran Sasso (LNGS), en Italie. Le travail présenté ici porte d'abord sur une étude de la réponse de l'argon aux reculs nucléaires et électroniques à basse énergie, réalisée par l’expérience ARIS. Le quenching nucléaire a été mesuré avec la meilleure précision à cette date et la probabilité de recombinaison a été comparée aux différents modèles décrivant le comportement de l’argon en présence d’un champ électrique. Une recherche de WIMP de faible masse effectuée avec les données DarkSide-50 est également présentée. Cette recherche porte sur le signal d'ionisation du TPC, conduisant à un seuil de détection beaucoup plus bas qu’en utilisant la scintillation. Les limites d'exclusion atteintes figurent parmi les meilleures pour des masses de WIMPs entre 2 et 6 GeV/c2 et sont les plus strictes pour une cible d'argon liquide. Enfin, une recherche préliminaire d'axions est présentée. Les axions sont un candidat alternatif à la matière noire, proposés comme solution au « problème CP fort ». Ils sont détectables dans DarkSide via leur couplage aux électrons. Cette recherche nécessitait l'amélioration de la modélisation des sources de fond en prenant en compte les effets atomiques dans les spectres d'émission bêta, ainsi qu'une redéfinition de l'échelle d'énergie convertissant l'énergie déposée dans l’argon en un certain nombre d'électrons extraits. Les résultats présentés montrent une sensibilité encourageante aux axions solaires et galactiquesThe existence of dark matter is known because of its gravitational effects, and although its nature remains undisclosed, one of the leading candidate is the weakly interacting massive particle (WIMP) with mass of the order of 100 GeV/c2 and coupling with ordinary matter at or below the weak scale. In this context, DarkSide-50 aims to direct observe WIMP-nucleon collisions in a liquid argon dual phase time-projection chamber located deep underground at Gran Sasso National Laboratory, in Italy. This work first details the argon calibration realised by the ARIS experiment. ARIS characterised the argon response to low energy nuclear and electronic recoils, down to unprecedented energies. The nuclear quenching was measured with the best precision to this date, and the recombination probability extracted was compared to different models describing the behaviour of argon in presence of an electric field. A search for low mass WIMPs performed with DarkSide-50 data is also presented. This search focuses on the ionisation signal from the TPC, leading much to much lower detection threshold. The achieved exclusion limits are amongst the leading ones, and the most stringent for a liquid argon target. Finally a preliminary search for axions is presented. Axions are an alternative candidate to dark matter, proposed as a solution to the strong CP problem. They are detectable in DarkSide via their coupling to electrons. This search required the improvement of the modelling of the background sources, by taking into account atomic effects in beta emission spectra, as well as a redefinition of the energy scale converting the energy deposited into a number of extracted electrons. The results presented show an encouraging sensitivity to both solar and galactic axions
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Clark, Matthew. "Direct-search method for the computer design of holograms." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301220.
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Jones, Evan Llewellyn. "The use of quadratic interpolation in direct search optimisation." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624549.
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Agnes, Paolo. "Direct search for dark matter with the DarkSide experiment." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC279/document.
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L’Univers est principalement constitué d’un ensemble d’éléments non baryoniques et non lumineux appelé la matière noire. L’un des candidats actuellement favorisés est une particule massive interagissant faiblement avec la matière ordinaire (WIMP) issue du Big Bang. Le programme DarkSide vise à la détection directe de WIMPs à l’aide d’une chambre à projection temporelle utilisant de l’argon liquide en double phase. La première étape de l’expérience, DarkSide-50 ( (46 ± 0,7) kg de masse active) est en cours d’exécution. Une première campagne, avec un remplissage d’argon atmosphérique(AAr), a produit la meilleure limite sur la section efficace WIMP-nucleon jamais obtenue par une expérience à base d’argon. La deuxième phase, avec un remplissage d’argon souterrain (UAr, appauvri en Ar-39), représente une étape importante vers la construction de DarkSide-20k, une expérience à bas bruit de fond avec une masse fiducielle de 20 t. Ce travail est principalement consacré à la description de la simulation Monte Carlo de DarkSide (G4DS), et à ses applications. G4DS, basé sur GEANT4, fournit la description géométrique de chaque détecteur du programme DarkSide ; il a été calibré afin de reproduire la réponse de DarkSide-50 avec une précision de l’ordre de 1 % et intègre un modèle spécifiquement développé pour la description des mécanismes d’ionisation et de scintillation dans l’argon liquide, étalonné sur des données expérimentales. Les principales applications de la simulation comprennent l’estimation du bruit de fond dû aux neutrons et gammas pour DarkSide-50, la mesure du facteur d’appauvrissement de l’Ar-39 en UAr par rapport à l’AAr et les études de conception pour DarkSide-20kA wide range of observational evidence suggests that the matter content of the Universe is dominated by a non-baryonic and non-luminous component: dark matter. One of the most favored candidate for dark matter is a big-bang relic population of Weakly Interacting Massive Particles (WIMPs). The DarkSide program aims to the direct detection of WIMPs with a dual-phase liquid argon TPC and a background free exposure. The first phase of the experiment, DarkSide-50, is running since Oct 2013 and has (46 ± 0.7) kg active mass. A first run, with an atmospheric argon fill (AAr), provided the most sensitive limit ever obtained by an argon-based experiment. The current run, with an underground argon fill (UAr, depleted in Ar-39), represents a milestone towards the construction of DarkSide-20k, a low-background dual-phase TPC with a fiducial mass of 20 t. This work is been mainly devoted to the description of G4DS, the DarkSide Monte Carlo simulation, and to its applications. G4DS is a GEANT4-based simulation, it provides the geometry description of each detector of the DarkSide program, it is tuned to reproduce the DarkSide-50 response at the percent level and incorporates a custom model for ionization and scintillation mechanisms in liquid argon, tuned on real data. The principal applications of the simulation include the estimate of the neutron and gamma backgrounds for DarkSide-50, the measurement of the Ar-39 depletion factor in UAr with respect to AAr and the design studies for DarkSide-20k
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Reuter, Robert. "Direct and indirect measures of learning in visual search." Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209542.
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In this thesis, we will explore direct and indirect measures of learning in a visual search task commonly called contextual cueing. In the first part, we present a review of the scientific literature on contextual cueing, in order to give the readers of this thesis a better general idea of existing evidence and open questions within this relatively new research field. The aims of our own experimental studies presented in the succeeding chapters are the following ones: (1) to replicate and extend the findings described in the various papers by Marvin Chun and various colleagues on contextual cueing of visual attention; (2) to explore the nature of memory representations underlying the observed learning effects, especially whether learning is actually implicit and whether memory representations are distinctive, episodic and instance-based or rather distributed, continuous and graded; (3) to extend the study of contextual cueing to more realistic visual stimuli, in order to test its robustness across various situations and validate its adaptive value in ecologically sound conditions;and (4) to investigate whether such knowledge about the association between visual contexts and “meaningful” locations can be (automatically) transferred to other tasks, namely a change detection task.
In a first series of four experiments, we tried to replicate the documented contextual cueing effect using a wide range of various direct measures of learning (tasks that are supposed to be related to explicit knowledge) and we systematically varied the distinctiveness of context configurations to study its effect on both direct and indirect measures of learning.
We also ran a series of neural network simulations (briefly described in the general discussion of this thesis), based on a very simple association-learning mechanism, that not only account for the observed contextual cueing effect, but also yield rather specific predictions about future experimental data: contextual cueing effects should also be observed when repetitions of context configurations are not perfect, i.e. the networks were able to react to slightly distorted versions of repeating contexts in a similar way than they did to completely identical contexts. Human participants, we conjectured, should therefore (if the simple connectionist model captures some relevant aspects of the contextual cueing effect) become faster at detecting targets surrounded by context configurations that are only partially identical from trial to trial compared to those trials where the context configurations were randomly generated. These predictions were tested in a second series of experiments using pseudo-repeated context configurations, where some distractor items were either displaced from trial to trial or their orientation changed, while conserving their global layout.
In a third series of experiments, we used more realistic images of natural landscapes as background contexts to establish the robustness of the contextual cueing effect as well as its ecological relevance claimed by Chun and colleagues. We furthermore added a second task to these experiments to study whether the acquired knowledge about the background-target location associations would (automatically) transfer to another visual search task, namely a change detection task. If participants have learned that certain locations of the repeated images are “important”, since they contain the target item to look for, then changes occurring at those specific locations should lead to less “change blindness” than changes occurring at other irrelevant locations. We used two different types of instructions to introduce this second task after the visual search task, where we either stressed the link between the two tasks, i.e. telling them that remembering the “important” locations for each image could be used to find the changes faster, or we simply told them to perform the second task without any reference to the first one.
We will close this thesis with a general discussion, combining findings based on our review of the existing research literature and findings based on our own experimental explorations of the contextual cueing effect. By this we will discuss the implications of our empirical studies for the scientific investigation of contextual cueing and implicit learning, in terms of theoretical, empirical and methodological issues.
Doctorat en sciences psychologiques
info:eu-repo/semantics/nonPublished
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Robertson, Blair Lennon. "Direct Search Methods for Nonsmooth Problems using Global Optimization Techniques." Thesis, University of Canterbury. Mathematics and Statistics, 2010. http://hdl.handle.net/10092/5060.
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This thesis considers the practical problem of constrained and unconstrained local optimization. This subject has been well studied when the objective function f is assumed to smooth. However, nonsmooth problems occur naturally and frequently in practice. Here f is assumed to be nonsmooth or discontinuous without forcing smoothness assumptions near, or at, a potential solution. Various methods have been
presented by others to solve nonsmooth optimization problems, however only partial convergence results are possible for these methods.
In this thesis, an optimization method which use a series of local and localized global optimization phases is proposed. The local phase searches for a local minimum
and gives the methods numerical performance on parts of f which are smooth. The localized global phase exhaustively searches for points of descent in a neighborhood of cluster points. It is the localized global phase which provides strong theoretical convergence results on nonsmooth problems.
Algorithms are presented for solving bound constrained, unconstrained and constrained nonlinear nonsmooth optimization problems. These algorithms use direct search methods in the local phase as they can be applied directly to nonsmooth problems because gradients are not explicitly required. The localized global optimization phase uses a new partitioning random search algorithm to direct random sampling into promising subsets of ℝⁿ. The partition is formed using classification and regression trees (CART) from statistical pattern recognition. The CART partition defines desirable subsets where f is relatively low, based on previous sampling, from which further samples are drawn directly. For each algorithm, convergence to an essential local minimizer of f is demonstrated under mild conditions. That is, a point x* for which the set of all feasible points with lower f values has Lebesgue measure zero for all sufficiently small neighborhoods of x*. Stopping rules are derived for each algorithm giving practical convergence to estimates of essential local minimizers. Numerical results are presented on a range of nonsmooth test problems for 2 to 10 dimensions showing the methods are effective in practice.
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Mok, Sungho. "Trade mark use in paid search marketing and direct liability." Thesis, Queen Mary, University of London, 2014. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8772.
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The thesis considers the scope of trade mark protection against the context of paid search marketing. The hypothesis is that ‘fair and efficient competition’ is at the heart of the balance between interested parties and between trade mark protection and between free speech. This introduces the concept of a 'virtuous cycle' in the application of trade mark law. this thesis suggests that fair and efficient competition should be the ultimate purpose of trade mark law. The concept can be furthered by protecting pro-competitive trade mark functions: the intra trade mark information function and the inter-trademark differentiation function. Thus, only where third party use third party use is likely to harm the information and differentiation functions of owners' trade marks user could be liable. In a democratic society, there is anadditional consideration:thebalance between trade mark protection and free speech. Where third parties use trade marks in non-commercial contexts, likelihood of confusion or dilution should be the result ofactual malice or calculated falsehood. These two considerations are tested against the real world context of paid search marketing. Based on the protection of pro-competitive trade mark functions and speech restriction standards, and the relevance of actual and direct context and circumstances of paid search marketing, advertisers can be liable for their use of trade marks even when they do not include trade marks in their advertisements. Search engines, however,are not responsible for their use ‘under current practices,’ whether or not trade marks are included in advertisements. The thesis supports that trade mark law and jurisprudence should transform the cycle that starts with the balance of interests and end with fair and efficient competition into a virtuous spiralwhere one feeds the other; the two are inextricably linked.
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Bengtlars, Ann, and Erik Väljamets. "Optimization of Pile Groups : A practical study using Genetic Algorithm and Direct Search with four different objective functions." Thesis, KTH, Bro- och stålbyggnad, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-146832.
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Piling is expensive but often necessary when building large structures, for example bridges. Some pile types, such as steel core piles, are very costly and it is therefore of great interest to keep the number piles in a pile group to a minimum. This thesis deals with optimization of pile groups with respect to placement, batter and angle of rotation in order to minimize the number of piles. A program has been developed, where two optimization algorithms named Genetic Algorithm and Direct Search, and four objective functions have been used. These have been tested and compared to find the most suitable for pile group optimization. Three real cases, two bridge supports and one culvert, have been studied, using the program. It has been difficult to draw any clear conclusions since the results have been ambiguous. This is probably because only three cases have been tested and the results are very problemdependent.The outcome depends, for example, on the starting guess and settings for the optimization. However, the results show that the Genetic Algorithm is somewhat more robust in its ability to remove piles than Direct Search and is therefore to prefer in pile group optimization.
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Nishimura, Hironobu. "Direction-sensitive direct dark matter search experiment with a gaseous TPC." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/124415.
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Scorza, Silvia. "EDELWEISS-II, direct Dark Matter search experiment : first data analysis and results." Phd thesis, Université Claude Bernard - Lyon I, 2009. http://tel.archives-ouvertes.fr/tel-00561621.
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One of the greatest mysteries of the universe that, for the present, puzzles the mind of most astronomers, cosmologists and physicists is the question: "What makes up our universe?". This is due to how a certain substance named Dark Matter came under speculation. It is believed this enigmatic substance, of type unknown, accounts for almost three-quarters of the cosmos within the universe, could be the answer to several questions raised by the models of the expanding universe astronomers have created, and even decide the fate of the expansion of the universe. There is strong observational evidence for the dominance of non-baryonic Dark Matter (DM) over baryonic matter in the universe. Such evidence comes from many independent observations over different length scales. The most stringent constraint on the abundance of DM comes from the analysis of the Cosmic Microwave Background (CMB) anisotropies. In particular, the WMAP (Wilkinson Microwave Anisotropy Probe) experiment restricts the abundance of matter and the abundance of baryonic matter in good agreement with predictions from Big Bang Nucleosynthesis. It is commonly believed that such a non-baryonic component could consist of new, as yet undiscovered, particles, usually referred to as WIMPs (Weakly Interacting Massive Particles). Some extensions of the standard model (SM) of particle physics predict the existence of particles that would be excellent DM candidates. In particular great attention has been dedicated to candidates arising in supersymmetric theories: the Lightest Supersymmetric Particle (LSP). In the most supersymmetric scenarios, the so-called neutralino seems to be a natural candidate, being stable in theories with conservation of R-parity and having masses and cross sections of typical WIMPs. The EDELWEISS collaboration is a direct dark matter search experiment, aiming to detect directly a WIMP interaction in a target material, high purity germanium crystal working at cryogenic temperatures. It relies in the measurement of nuclear recoils that produce measurable effects in the crystal such ionization and heat. My PhD thesis is organized as follows. The first chapter aims to provide an introduction to the theoretical framework and the scientific motivation for the following work. The nature of DM has been one of the most challenging topics in contemporary physics since the first evidences of its existence had been found in the 1930s. Cosmologists and astrophysicists on one side, together with particle theorists on the other have put a lot of effort into this field: I will briefly account for their achievements and for the experimental strategies which can be set in this scenario. Since this thesis work was carried out within the EDELWEISS-II direct dark matter experiment, I will focus the next chapter on this topic, describing the main features. The second chapter is related to the set-up of the EDELWEISS-II, the current stage of the EDELWEISS experiment necessary after a first phase that achieved the best upper limit on the WIMP elastic scattering on nucleon as a function of WIMP mass in 2004. [....]
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Panning, Thomas D. "Deterministic Parallel Global Parameter Estimation for a Model of the Budding Yeast Cell Cycle." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/33360.
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Two parallel deterministic direct search algorithms are combined to find improved parameters for a system of differential equations designed to simulate the cell cycle of budding yeast. Comparing the model simulation results to experimental data is difficult because most of the experimental data is qualitative rather than quantitative. An algorithm to convert simulation results to mutant phenotypes is presented. Vectors of the 143 parameters defining the differential equation model are rated by a discontinuous objective function. Parallel results on a 2200 processor supercomputer are presented for a global optimization algorithm, DIRECT, a local optimization algorithm, MADS, and a hybrid of the two. A second formulation is presented that uses a system of smooth inequalities to evaluate the phenotype of a mutant. Preliminary results of this formulation are given.Master of Science
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Hogan, Emma. "A direct imaging search for substellar and planetary mass companions around white dwarfs." Thesis, University of Leicester, 2008. http://hdl.handle.net/2381/3955.
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Even though the radial velocity technique has detected almost all of the 269 extrasolar planets discovered to date, this method does not directly observe the light from the planet. The ability to directly detect this light would allow spectra of extrasolar planets to be obtained, providing information about their information and evolution through the investigation of their composition and structure. To date, none of the extrasolar planets found using the radial velocity technique have been directly imaged, as these faint companions are too close to their bright parent stars. White dwarfs are intrinsically faint objects and can be upto 10,000 times less luminous than their main sequence progenitors, substantially increasing the probability of directly imaging an extrasolar planet in orbit around them. The Degenerate Objects around Degenerate Objects (DODO) survey aims to obtain a direct image of an extrasolar planet in a wide orbit around a white dwarf. By acquiring J band images of 26 equatorial and northern hemisphere white dwarfs a year or two apart, common proper motion companions to the white dwarfs can be identified. The discovery of such a system could supply new information on the frequency and mass distribution of extrasolar planets around intermediate mass main sequence starts and confirm whether these companions can survive the final stages of stellar evolution. In addition, the direct detection of an extrasolar planet in orbit around a white dwarf would allow the spectroscopic investigation of planets much older than any previously found. Using the 24 white dwarfs in the DODO survey within 20pc, the frequency of substellar companions with effective temperatures > 500K and projected physical separations from the white dwarf between 60-200AU is estimated to be <5%. For the same range of projected physical separations, the frequency of substellar companions with masses >10Mjup is estimated to be<9%.
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Beagle, Ronda J. "The Navy's search for a few good women: analysis of a direct mail campaign." Thesis, Monterey, California. Naval Postgraduate School, 1993. http://hdl.handle.net/10945/27157.
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The purpose of this thesis was to attempt to select significant individual characteristics of women who met Navy Recruiting Command standards for enlisting in technical rates. Additionally it attempted to select geographic characteristics of these qualified women. To that end, a logistic regression analysis was conducted on data from approximately 100,000 qualified high school juniors and seniors. For a student to be qualified for this study, she must have scored above the 31st percentile on the AFQT and above the 50th percentile on one of three subtests: Auto-Shop Information, Electronics Information, or Mechanical Comprehension. The database contained Military Entrance Processing Command files and 1990 Census data. This research found for individual regression models interaction effects were present between future plans and geographic area, and between service preference and geographic area when determining interest in the military. It found for geographic regression models the proportion of students interested in military service out of those available increased in geographic areas (Naval Recruiting Districts) where more personnel were in the armed forces, more people were associated with technical occupations, and where median family income was higher. The analysis found the proportion of students available for military service out of the target market population (females aged 17-21 years) decreased in geographic areas where unemployment rate was higher, more people were associated with technical occupations, more people lived below the poverty level, and where median family income was higher
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Cass, A. J. "A search for jets in direct photon events from hadronic collisions at 280GeV/c." Thesis, University of Liverpool, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234824.
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Spratt, Spencer. "A search for direct transcriptional targets of Hedgehog signalling involved in late neuronal cell differentiation." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426095.
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Le, Calloch Maxime. "Study of the single electron charge signals in the XENON100 direct Dark Matter search experiment." Nantes, 2014. https://archive.bu.univ-nantes.fr/pollux/show/show?id=f4984b95-6904-4ff8-bcd6-50f3768ac873.
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A partir de l’observation de l’Univers, il a été démontré que la masse associée à la matière visible ne représente que quelques pourcents de son budget énergétique total. La partie restante est composée de l’énergie noire, responsable de l’expansion cosmologique, et d’une matière invisible, la matière noire. La famille de particules la plus probable pour décrire cette matière noire est appelée WIMP. Ces particules peuvent être directement détectées par la mesure du recul nucléaire induit lors d’une diffusion élastique au sein d’un matériau scintillant. Pour cela, la Collaboration XENON a développé un détecteur placé sous terre, consistant en une chambre à projection temporelle (TPC) et utilisant du xénon sous deux phases: liquide et gazeuse. La différence de taux d’ionisation des atomes rencontrés pour un recul nucléaire induit par un WIMP, par rapport à un recul électronique induit par des sources de bruit de fond b ou g, conduit à des rapports différents entre les signaux émis en phase liquide et gazeuse. Cette différence est utilisée pour isoler les WIMPs du bruit de fond. Une bonne connaissance du signal d’ionisation est donc requise pour un tel détecteur. Dans ce contexte, la réponse du détecteur XENON100 aux signaux de charge d’électrons uniques est étudiée. Ils correspondent à des faibles signaux émis en phase gazeuse par un ou plusieurs électrons extraits en coïncidence temporelle. Grâce à cette analyse, une méthode innovante pour calculer le rendement d’extraction des électrons du liquide vers le gaz a été établieFrom the observation of the Universe, it has been demonstrated that the mass associated to visible matter represents only few percent of its energetic budget, while the remaining part is composed by dark energy, responsible to the cosmological expansion, and by some hidden matter, the dark matter. The likeliest particles family used to describe this dark matter is called WIMP (Weakly Interacting Massive Particles). That kind of particles could be directly detected by measuring nuclear recoil during an elastic scattering inside a scintillating material. For this, the XENON Collaboration has developed a detector consisting in a time projection chamber (TPC) using xenon dual phase (liquid and gas) detector, and placed underground. The different ionization density of nuclear recoils induced by WIMPs, and electronic recoils induced by β particles or g rays background source, leads to different ratio between both signals, in the liquid and in the gas phase, and is used to discriminate WIMPs from background. A good knowledge of the ionization signal is strongly required for such a detector. In this context, the XENON100 response to single electron charge signals is investigated. They correspond to very tiny signals emitted in the gas phase by one or few electrons extracted in time coincidence. Thanks to this analysis, an innovative method to establish the extraction yield of electrons from the liquid to the gas phase has been drawn, allowing to explore a key information to reject electronic recoils from nuclear ones
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Fokwa, Tsafack Jean B. "In search for direct corporate responsibility for human rights violations in Africa: which way forward?" Diss., University of Pretoria, 2004. http://hdl.handle.net/2263/1082.
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"This study centres on the presumption that, given the unprecedented economic power of corporations, it is vital to clarify the legal issues surrounding the responsibility of corporations for human rights violations and to look at avenues for asserting responsibility. Consequently, this study focuses on the responsibility concept for corporate human rights violations and the objective of this study is to explore, examine and assess various avenues for asserting responsibility for corporate human rights violations. The study recommends other avenues for asserting responsibility for corporate human rights violations in Africa. The study therefore raises four issues. The first phase seeks to focus on how globalisation has triggered the proliferation of corporations in national economies in Africa and the impact on human rights issues taking into cognisance the responsibility concept vis a vis corporations. The second part seeks to examine state responsibility for the acts of corporations. This discussion will focus on the International Rules on State Responsibility and obligations of states under international human rights law with reference to certain human rights instruments that confer a duty on states to respect and to ensure to all citizens within their territories and subject to their jurisdiction the rights recongnised in these instruments. This discussion basically seeks to review the dominant approach to human rights treaties and the relevant instruments to assess the available avenues in asserting responsibility on the state for corporate human rights violations. This study will assess home and host state responsibility and argue that the host state cannot certainly be regarded as the main bearer of responisiblity for violations of human rights due to the powerful characteristics of corporatoins. The jurisprudence of the African Commission on Human and Peoples' Rights will also be taken into consideration in examining the legal responsibility of states under international human rights law for corporate human rights violations. Part three of this study will addres the question of asserting direct responsibility on transnational corporations for human rights violations. While some remarks will be made on non-legal responsibilities or soft law, my interest will however be to examine and assess the suitability of human right principles and instruments that confer direct responsibility on corporations for human rights violations. The discussion will also take cognisance of some treaties that confer direct criminal responsibility on corporations for human rights violations. The fourth and concluding part will attempt to look at the need for internaitonal legally binding regulations of corporations. This discussion will attempt to focus on the application and implications of international legally binding regulation in Africa as a means of reforming and strengthening direct corporate criminal responsibility for human rights violations. Recommendations geared towards the legal reform of asserting direct responsiblity on transnational corporations in Africa will then be made." -- Introduction.Thesis (LLM (Human Rights and Democratisation in Africa)) -- University of Pretoria, 2004.
Prepared under the supervision of Prof. Kingsley K. K. Ampofo, Faculty of Law, University of Ghana
http://www.chr.up.ac.za/academic_pro/llm1/llm1.html
Centre for Human Rights
LLM
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Yeh, Shea-Tinn. "Integrated Faceted Browser and Direct Search to Enhance Information Retrieval in Text-Based Digital Libraries." Wright State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=wright1252951819.
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Flacco, Christian Julienne. "A search for direct CP Violation in two-body cabibbo-suppressed decays of neutral charmed mesons /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2006. http://uclibs.org/PID/11984.
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Reichhart, Lea. "ZEPLIN-III direct dark matter search : final results and measurements in support of next generation instruments." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/7914.
Full textAbstract:
Astrophysical observations give convincing evidence for a vast non-baryonic component, the so-called dark matter, accounting for over 20% of the overall content of our Universe. Direct dark matter search experiments explore the possibility of interactions of these dark matter particles with ordinary baryonic matter via elastic scattering resulting in single nuclear recoils. The ZEPLIN-III detector operated on the basis of a dualphase (liquid/gas) xenon target, recording events in two separate response channels { scintillation and ionisation. These allow discrimination between electron recoils (from background radiation) and the signal expected from Weakly Interacting Massive Particle (WIMP) elastic scatters. Following a productive first exposure, the detector was upgraded with a new array of ultra-low background photomultiplier tubes, reducing the electron recoil background by over an order of magnitude. A second major upgrade to the detector was the incorporation of a tonne-scale active veto detector system, surrounding the WIMP target. Calibration and science data taken in coincidence with ZEPLIN-III showed rejection of up to 30% of the dominant electron recoil background and over 60% of neutron induced nuclear recoils. Data taking for the second science run finished in May 2011 with a total accrued raw fiducial exposure of 1,344 kg days. With this extensive data set, from over 300 days of run time, a limit on the spin-independent WIMP-nucleon cross-section of 4.8 10-8 pb near 50 GeV/c2 WIMP mass with 90% confidence was set. This result combined with the first science run of ZEPLIN-III excludes the scalar cross-section above 3.9 10-8 pb. Studying the background data taken by the veto detector allowed a calculation of the neutron yield induced by high energy cosmic-ray muons in lead of (5.8 0.2) 10-3 neutrons/muon/(g/cm2) for a mean muon energy of 260 GeV. Measurements of this kind are of great importance for large scale direct dark matter search experiments and future rare event searches in general. Finally, this work includes a comprehensive measurement of the energy dependent quenching factor for low energy nuclear recoils in a plastic scintillator, such as from the ZEPLIN-III veto detector, increasing accuracy for future simulation packages featuring large scale plastic scintillator detector systems.
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Stevens, Donald Garth. "A behavioural data approach towards predicting direct real estate markets in the United Kingdom." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/277014.
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In recent years, modern prediction models have evolved to include behavioural data such as user-generated search query data that capture market sentiment and reach beyond the grasp of established macroeconomic indicators. These applications had considerable success in predicting a wide range of economic phenomena with the assumption that internet interaction behaviour resembles probable offline behaviour. Despite the considerable success of this approach, the existing literature argues for the continuous validation of search query keywords and its probable meaning over time to avoid spurious and biased results. Although recent literature attempted to bridge the keyword validation gap, this line of research is still in its infancy. This thesis sets out to examine the validity of web search intention to serve as a “pure” demand proxy for direct real estate market prediction in the United Kingdom. More specifically, it is directed towards constructing web search indices to explore: (i) the extent to which an individual’s true real estate orientated intentions manifest themselves in their web search behaviour and (ii) the magnitude to which real-time information adds value towards the prediction of illiquid asset classes. In doing so, a conceptual framework is produced, which outlines the logic and importance associated with intention specific web search in the digital age, as well as its relation to real estate demand. The empirical findings suggest that intention specific keyword development might be of little importance for aggregate housing and office market forecasts in the United Kingdom. On the contrary, it seems that the viability of intention specific web search keyword development increases when it is directed at a specific regional market. The overall thesis narrative introduces a new way of thinking about web search in the context of economic demand and draws from a variety of principles and methodologies to establish an avenue from which future research can be conducted.
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Maccolini, Serena. "Search for CP violation in D±s→K0Sπ±, D±→K0SK± and D±→φπ± decays." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15840/.
Full textAbstract:
Il lavoro qui presentato riporta una ricerca preliminare di violazione $C\!P$ nei decadimenti singolarmente-Cabibbo-soppresi $D_s^\pm \rightarrow K_S^0 \pi^\pm$, $D^\pm \rightarrow K_S^0 K^\pm$ e $D^\pm \rightarrow \phi \pi^\pm$, ricostruiti in un campione di dati corrispontene a 2 fb$^{−1}$ di luminosità integrata raccolta da LHCb durante il Run-2 (2015-2016). Le asimmetrie di violazione $C\!P$ sono misurate separatemente come
\begin{eqnarray*}
\mathcal{A}_{CP}(D_s^\pm \rightarrow K_S^0 \pi^\pm) & = & (0.03 \pm 0.40 \,\mathrm{(stat.)})\%,\\
\mathcal{A}_{CP}(D^\pm \rightarrow K_S^0 K^\pm) & = & (0.04 \pm 0.15 \,\mathrm{(stat.)})\%,\\
\mathcal{A}_{CP}(D^\pm \rightarrow \phi \pi^\pm) & = & (-0.124 \pm 0.045 \,\mathrm{(stat.)})\%,
\end{eqnarray*}
assumendo che la violazione $C\!P$ nei decadimenti Cabibbo-favoriti sia trascurabile. I risultati sono consistenti con quelli delle analisi precedenti. Dato che i risultati sono compatibili con zero, non è stata trovata alcuna evidenza di violazione $C\!P$ con la statistica attualmente analizzata. Tuttavia, i risultati sono prelimari poiché ulteriori studi, come quelli di valutazione delle principali sistematiche, sono ancora in corso.
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Macías, Cubeiro Rosa. "Development and Implementation of a Search and Locate Actuator System." Thesis, KTH, Elektrisk energiomvandling, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-109706.
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Over the last years, electrical roads have emerged as a cost effective and environmentally friendly solution towards a transportation system with less dependency on fossil fuels. This thesis presents the design of a search and locate system for road-bound conductive electrical roads with position control in two axes. The system is intended to find and follow the position of an electrified rail. The actuator system constitutes a firm groundwork for further research and development in this field. A laboratory test set up has been designed and both hardware and software parts have been constructed. The control of the system uses the CompactRIOTM technology from National Instruments. Results from the practical evaluation suggest that the non-linear characteristic of the system and the lack of direct position feedback from the motor rotation are the main causes of a non-accurate position control. Future development steps should focus on improving the mechanical design and include encoder feedback for the control loop as well as absolute automatic control with the incorporation of rail sensors.
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Gareau, Paul. "The impact of direct-to-consumer advertising of prescription medicine on the consumer's intention to perform external search." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0020/MQ55676.pdf.
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Jatzeck, Bernhard Michael. "The application of the Luus-Jaakola direct search method to the optimization of a hybrid renewable energy system." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0014/NQ59603.pdf.
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Sosa, Nicholas. "Looking for Meaning in All the Wrong Places: The Search for Meaning After Direct and Indirect Meaning Compensation." Ohio University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1486982633785334.
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Yao, Li. "The effect of direct current electric fields on hippocampal neurons in vitro." Thesis, University of Aberdeen, 2005. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU487878.
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Initiation and effectiveness of neuron migration to the right places are critical for the development and repair of central nervous system. It is now confirmed that mammalian, including human central nervous system (CNS) contains stem cells and nerve progenitor cells. Upon brain injury either from ischemia or trauma, those cells must be able to proliferate and migrate to the damaged parts in order to repair the damage. To understand the underlying mechanisms and find new techniques of directing neuron growth are of both scientific and medical significance. Endogenous electric fields (EFs) are widespread in developing and regenerating tissues. During embryonic development, endogenous EFs exist rostrocaudally and mediolaterally at the neural plate and neural fold stages. The size, location and developmental timing of EFs correlate with active neuron migration. Therefore, electric fields may provide a signal to direct cellular behavior of nerve cells during nervous system development and reparation. Application of EFs directs cell migration of many types of cells. However, whether neurons migrate directionally in applied electric fields has not been demonstrated. I have investigated the effects of applied physiological EFs on cultured hippocampal neurons and the underlying mechanisms. Hippocampal neurons from rats and mice were cultured on poly-L-lysine and laminin coated dishes and were identified with MAP-2 (a specific marker for neuron) staining. The neurons were exposed to small applied electric fields and the migration and division were recorded with an imaging system. 1. In a DC electric field, dissociated rat hippocampal neurons migrate to the cathode. The migration direction was reversed when the EF polarity was reversed. Neuronal migration in EFs involes the same steps as that in non-EF cultures, namely leading process extension, nuclear translocation and retraction of trailing process. 2. The cathodal migration of hippocampal neurons is voltage and time dependent. A DC EF does not have significant influence on neuronal migration speed. This result shows that the effect of EFs is different on neuronal migration speed and direction of migration. 3. The guidance effect of EFs is also seen in neuronal migration from hippocampal micro-explants and neuronal migration along glial process. Both types of migration are towards the cathode. 4. Electric fields direct growth cone path finding and neurite orientation. EF induced neurite orientation showed time and voltage dependence. Leading process branching, turning and swapping over of leading and trailing processes are the main types of neurite re-orientation. Guided neuronal migration and neuron leading process orientation are not accompanied with neuronal size change. 5. In an applied EF, MAP-2 (microtubule associated protein 2), p-Akt, Golgi apparatus and centrosome redistribute asymmetrically to the cathode facing side of hippocampal neurons. 6. Inhibition of ROCK (Rho-associated protein kinase) and Pi3k (phosphoinositide-3 kinase) with inhibitors decreases leading neurite orientation and Golgi polarization in the neurons in response to the EFs. They also decrease the directedness and speed of guided neuronal migration in EFs. 7. Null mutation of p110gamma, which encodes the catalytic domain of Pi3k gamma significantly decreased the electric field directed neuron migration. These results suggest that ROCK and Pi3k regulate EFs directed neuronal migration. 8. Application of electric fields also affects cell division of postnatal hippocampal neurons. The neuronal phenotype of divided cells was confirmed with MAP-2 and GFAP staining. Most cells divided with a cleavage plane perpendicular to the EF vector. 9. Using vibrating probe techniques, we show that there is a significant change in electric currents upon wounding hippocampus in vitro. In conclusion, this study demonstrates that hippocampal neurons from both rat and mice respond to applied EFs by directional migration and directional division. The electric field directed neuronal migration involves ROCK and Pi3k signaling. This raises the possibilities that 1) there may be a neglected role for endogenous electric fields in directing neuron migration and division; 2) electric fields may be used as a potential cue to direct neuronal migration in repair of the central nervous system.
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Horák, Jan. "Analýza společnosti Executive Search v kontextu českého trhu práce." Master's thesis, Vysoká škola ekonomická v Praze, 2012. http://www.nusl.cz/ntk/nusl-162768.
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The theoretical part of this thesis describes internal and external ways that can be of use while appointing employees. The thesis is focused on using direct systematic search (Executive Search) in the environment of consulting company CSP Partners Ltd. and its aim is to show the specific features of this method usually used to appoint specialists or managers. Commercial and executive processes of the company are depicted within the text. Using analytical tools this thesis examines the whole HR consulting industry in the context of Czech labor market. Historical development and recent trends are included, ethical dimension as well as motivation of candidates approached using this method are described as well. Many practical notes are involved and the final part describes one of CSP Partners' Ltd. projects in detail.
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McGuire, Patrick Charles. "Low-background balloon-borne direct search for ionizing massive particles as a component of the dark galactic halo matter." Diss., The University of Arizona, 1994. http://hdl.handle.net/10150/186654.
Full textAbstract:
A dark matter (DM) search experiment was flown on the IMAX balloon payload, which tested the hypothesis that a minor component of the dark matter in the Galactic halo is composed of ionizing (dE/dx > 1 \ MeV/g/cm² or σ > 2 x 10⁻²⁰ cm²) supermassive particles (mₓ ∈ [10⁴,10¹²] GeV/c²) that cannot penetrate the atmosphere due to their low velocities (β ∈ [0.0003, 0.0025]). The DM search experiment consisted of a delayed coincidence between four ∼ 2400 cm² plastic scintillation detectors, with a total acceptance of ∼ 100 cm² sr. In order to search for ultra-slow particles which do not slow down in the IMAX telescope, the experiment contained TDCs which measured the time-delays T(i,i+1) ∈ [0.3, 14.0] μs between hits in successive counters ∼ 1% precision. Using the first 5 hours of data at float altitude (5 g/cm² residual atmosphere), we observed ∼ 5 candidate non-slowing dark matter events, consistent with the background from accidental coincidences of 4 events. This implies that the DM flux is less than 6.5 x 10⁻⁶cm⁻²s⁻¹sr⁻¹ (95% C.L.). Similar results were also obtained for particles which slow down in the counter telescope. This experiment effectively closes much of a previously unconstrained 'window' in the mass/cross-section joint parameter space for massive particles as the dominant halo DM, and implies that for certain regions of this parameter space massive particles cannot be more than one part in 10⁵ by mass of all the DM. These results can also directly constrain 'light' magnetic monopoles and neutraCHAMPs in a previously unconstrained mass region mₓ ∈ [10⁶,10⁹] GeV.
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Abulaiti, Yiming. "Search for Direct Top Squark Pair Production with the ATLAS Experiment and Studies of the Primary Vertex Reconstruction Performance." Licentiate thesis, Stockholms universitet, Fysikum, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-105746.
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The ATLAS detector is one of the two largest experiments installed at the Large Hadron Collider at CERN, the European Organization for Nuclear Research. During the first run, the ATLAS detector recorded data at centre of mass energies of 7 TeV and 8 TeV, enabling many precision measurements and new physics searches. One important task in ATLAS is measuring the primary vertex, the interaction point of the hardest proton-proton collision in an event. In this thesis, a study of the primary vertex reconstruction performance in data and simulated events using $t\bar{t}$ and ${Z}$ events is presented. Within the statistics available, the performance in data and simulated events is found to be compatible. Motivated by the limitations of the Standard Model of particle physics, searches for supersymmetric particles are performed with the ATLAS experiment. No signal has been observed so far, and the results are used to set exclusion limits on the masses of the supersymmetric particles. As the exclusion limits are derived from analyses which each target only a single decay mode of a supersymmetric particle, the analyses might have lower sensitivity to more complex decay scenarios. In this thesis the sensitivity of one of the ATLAS searches for direct top squark pair production to models with more complex decay modes is investigated. The study concludes that the sensitivity to models where the top squark can decay via heavier charginos and neutralinos is lower than the sensitivity to models where only decays to the lightest chargino or neutralino are present.
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Heidrich-Meisner, Verena [Verfasser], Gregor [Gutachter] Schöner, and Christian [Gutachter] Igel. "Evolutionary direct policy search in noisy environments / Verena Heidrich-Meisner ; Gutachter: Gregor Schöner, Christian Igel ; Fakultät für Physik und Astronomie." Bochum : Ruhr-Universität Bochum, 2011. http://d-nb.info/1217845216/34.
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Hüske, Nils Kristian. "The Higgs boson in the standard model : theoretical constraints and a direct search in the WH channel at the Tevatron." Paris 6, 2010. http://www.theses.fr/2010PA066187.
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Bone, John D. "The culture of the 'con man' : an ethnographic study of 'value' direct selling organisations." Thesis, University of Aberdeen, 2003. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU176421.
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This thesis is an ethnographic study conducted within two home improvement 'Value' Direct Selling organisations (VDSOs) in the UK. This industry and form of selling have been overlooked by sociologists thus far despite its potential as a rich sociological field of enquiry. Home improvement VDSOs are engaged in the selling of high priced durables, such as replacement windows, fitted kitchens and related products directly to customers in their own homes. A key characteristic of the industry is its reliance on pro-active persuasion, impression management and emotional labour on the part of its operatives, as a means of finding new customers and selling its products. Deception and misrepresentation are integral to the industry's operations on a number of levels. This extends to the nature of the organisations themselves, where their public image belies their internal reality. As well as providing an account of the industry's interaction order, culture and organisational features, the site also provides a vehicle for the exploration of themes that are central to current sociological debates. The thesis sets out to provide fresh insights into some key sociological issues, such as trust, emotional labour, identity processes and the relationship between rationality and irrationality within contemporary organisational settings.
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He, Jian. "Global Optimization of Transmitter Placement for Indoor Wireless Communication Systems." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/34817.
Full textAbstract:
The DIRECT (DIviding RECTangles) algorithm JONESJOTi, a variant of
Lipschitzian methods for bound constrained global optimization, has
been applied to the optimal transmitter placement for indoor wireless
systems. Power coverage and BER (bit error rate) are considered as
two criteria for optimizing locations of a specified number of
transmitters across the feasible region of the design space. The
performance of a DIRECT implementation in such applications depends
on the characteristics of the objective function, the problem
dimension, and the desired solution accuracy. Implementations with
static data structures often fail in practice because of unpredictable
memory requirements. This is especially critical in $S^4W$
(Site-Specific System Simulator for Wireless communication systems),
where the DIRECT optimization is just one small component connected
to a parallel 3D propagation ray tracing modeler running on a 200-node
Beowulf cluster of Linux workstations, and surrogate functions for a
WCDMA (wideband code division multiple access) simulator are also
used to estimate the channel performance. Any component failure of this
large computation would abort the entire design process. To make the
DIRECT global optimization algorithm efficient and robust, a set of
dynamic data structures is proposed here to balance the memory
requirements with execution time, while simultaneously adapting to
arbitrary problem size. The focus is on design issues of the dynamic data
structures, related memory management strategies, and application issues
of the DIRECT algorithm to the transmitter placement optimization for
wireless communication systems. Results for two indoor systems
are presented to demonstrate the effectiveness of the present work.Master of Science
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Kéfélian, Cécile. "Search for dark matter with EDELWEISS-III excluding background from muon-induced neutrons." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1020/document.
Full textAbstract:
Le but de l'expérience EDELWEISS est la détection directe de matière noire sousforme de WIMPs, par l'étude de leur diffusion élastique sur les noyaux de germanium des détecteurs bolomètriques. Le plus problématique des bruits de fond provient des neutrons pouvant mimer l'interaction d'un WIMP dans un détecteur. Ces neutrons sont notamment produits par les rares muons cosmiques de haute énergie qui atteignent le laboratoire souterrain malgré les 4800 m w.e. de roche. Les muons résiduels sont détectés par un système veto de 46 modules de scintillateur plastique entourant l'expérience, qui permet de rejeter la plupart du bruit de fond associé. La détermination précise du bruit de fond neutron résiduel induit par ces muons dans EDELWEISS-III, essentielle pour l'identification des WIMPs, est le but de cette thèse. Le taux de bruit de fond dépend de la géométrie de l'expérience ainsi que des matériaux utilisés, qui ont subi d'importantes modifications depuis EDELWEISS-II. Des simulations GEANT4 du passage des muons dans la nouvelle géométrie ont été réalisées afin d'extraire le taux d'événements induits par les muons dans les bolomètres. Ce taux est en bon accord avec le taux mesuré extrait des données du Run308. En parallèle, une limite inférieure sur l'efficacité du veto muon a été extraite à partir des données bolomètres. Une nouvelle méthode basée sur l'utilisation d'une source d'AmBe a été développée afin d'extraire l'efficacité de chaque module de la simulation. À partir de ces résultats, il a été montré que le bruit de fond attendu est négligeable pour la recherche de WIMPs avec les données du Run308 et ne limitera pas la sensibilité future d'EDELWEISS-IIIThe aim of the EDELWEISS-III experiment is to detect the elastic scattering of WIMPs from the galactic dark matter halo on germanium bolometers. The most problematic background arises from neutrons, which can mimic a WIMP interaction in a detector. Neutrons are notably induced by high energy cosmic ray muons reaching the underground laboratory despite the 4800 m w.e. of rock overburdened. Remaining muons are tagged using an active muon-veto system of 46 plastic scintillator modules surrounding the experiment, which allows to reject most of the associated background. The goal of this thesis was to give a precise estimation of the irreducible muon-induced neutron background, needed to identify a potential WIMP signal. The expected background depends on the geometry of the experiment as well as on the used materials, both strongly modified since EDELWEISS-II. Geant4-based simulations of muons through the modified geometry were performed to derive the rate of events induced by muons in the bolometer array. This rate has been shown to be in good agreement with the measured one extracted from the Run308 data. In parallel, a lower limit on the muon-veto efficiency was derived using bolometer data only. A new method based on an AmBe source was developed to extract precisely the detection efficiency of individual modules from the simulation. From these results, it was shown that the expected background is negligible for the WIMP search analyses performed with the Run308 data and won't limit the future sensitivity of the EDELWEISS-III experiment
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Alberts, Andreas Jacobus. "Building a scalable virtual community on commodity hardware and open source software / by Andreas Alberts." Thesis, North-West University, 2008. http://hdl.handle.net/10394/4162.
Full textAbstract:
The information era has brought upon us waves of change that brings affordable technology Within the reach of the average person. Computers connected to the Internet,
part of our daily living, have led to the formation of online communities.
In the spirit of communal efforts, a community cannot be controlled or managed into a
specific form or direction. A community has a need to concentrate its efforts towards
a common goal or vision, therefore sufficiently nonrestrictive infrastructure is needed to
enable the community members to contribute towards their goal.
We design and build infrastructure to support a virtual community, according to the
needs of the community. Community members can easily locate and exchange files
among each other, interact in private and public chat rooms by means of instant text
messages, as well as make announcements and participate in group discussions in a Web
based environment. Additional needs are identified and tended to by means of various value adding services. We also formulate a management strategy to lead the community
towards self-sustenanceThesis (M. Ing. (Computer and Electronical Engineering))--North-West University, Potchefstroom Campus, 2009.
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Jurgaitytė, Eugenija. "Tiesioginio paieškos metodo lyderio ir pasekėjo uždaviniui realizacija." Bachelor's thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20140716_144050-91473.
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Šio bakalauro darbo tikslas - realizuoti tiesioginės paieškos metodą (lyderio ir pasekėjo uždaviniui). Šiam tikslui pasiekti buvo nagrinėjama tiesioginio paieškos metodo (lyderio ir pasekėjo uždaviniui) matematinė formuluotė ir algoritmas pateikti Dali Zhang ir Gui-Hua Lin darbe„Dviejų lygių tiesioginės paieškos metodas lyderio – pasekėjo uždaviniui ir taikymams“ (angl. „Bilevel Direct Search Method for Leader – Follower Equilibrium Problems and Applications“). Darbo metu buvo sukurta programa, realizuojanti metodą, metodas pritaikytas oligopolinės rinkos modeliui (deterministiniam, nedeterministiniam, stochastiniam) spręsti, taip pat metodas pritaikytas oligopolinės rinkos modeliui, kai algoritmo parametrai generuojami atsitiktinai.The purpose of this bachelor work – to realize the Direct Search Method (for Leader - Follower problem). To achieve this aim was analyzed the mathematical formulation of direct search method and algorithm that were submitted at paper of Dali Zhang and Gui-Hua Lin „Bilevel Direct Search Method for Leader – Follower Equilibrium Problems and Applications“. During this work was developed a program for realizing the method. The method was adapted for oligopolistic market model (deterministic, non-deterministic, stochastic), also, method was adapted for oligopolistic market model, when the parameters of algorithm are generated randomly.
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Rashed, Mohamed El-Sayed. "Design and implementation of sensorless vector and direct torque control induction motor drives for low speed operation." Thesis, University of Aberdeen, 2002. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU602300.
Full textAbstract:
The invention of the Rotor Field Oriented Control (RFOC) has made the induction machine (IM) dominate the high performance drives market. Fifteen years later, the Direct Torque Control (DTC) strategy has been introduced to give fast torque and flux control with reduced software and hardware requirements. However, the use of flux, speed, current and three-phase stator voltage sensors to monitor the drive states increase the drive cost and reduce the overall system reliability. The number of sensors can be minimised using estimation. However, estimation at low stator frequency operation suffers from pure integration, stability problems, observablity problems, parameter detuning and inverter non-linearity. Thus, it has been suggested to develop and implement stable sensorless RFOC and DTC drives with stator and rotor resistance estimators that can work at low stator frequency with minimal number of sensors. Thus, two types of model reference adaptive system (MRAS) estimators that do not include pure integration have been adopted. A novel design procedure based on linear control theory has been stated to design stable speed, stator resistance and rotor resistance estimators in various operating modes for individual and simultaneous use. The observablity problem at zero stator frequency operation has been eliminated using high frequency injection. The inverter non-linearity has been modeled and thus the model has been used to compensate the inverter voltage losses. The designed estimators have been employed to realise and implement stable sensorless RFOC and DTC IM drives that work at low stator frequency. Furthermore, the classic DTC with fixed switching frequency suffers from torque ripples, flux ripples, torque control offset and flux collapse at low speed and light load. A novel torque ripple minimisation (TRM) DTC scheme has been proposed to predictively eliminate the torque ripple and reduce the flux ripple and also eliminate the torque offset and the flux collapse. In addition, a novel Space Vector Modulation (SVM) DTC has been proposed as an alternative to the TRM DTC scheme and has shown better performance and less computational time. To achieve successful development of sensorless RFOC and DTC drives which can work at low speeds, well-designed stable estimators are the key factor. This research work has given important contribution towards clear vision to analyse and design stable parameter estimators for RFOC and DTC IM drive. It follows, stable speed and stator and rotor resistance MRAS based on back-EMF estimators have been designed for individual and simultaneous use, following the proposed design procedure. These estimators have been employed to implement a stable sensorless RFOC IM drive for low speed operation that insensitive to parameters variation. The performance of the drive has been investigated extensively using simulations and experimental work. In addition, stable speed and stator and rotor resistance MRAS based on current estimation estimators have been designed for individual and simultaneous use. These estimators have been also used to realise a stable sensorless RFOC IM drive for low speed operation. Simulations and experimental work have been carried out to also investigate the performance of the drive. These stable estimators have been also employed to develop two stable sensorless SVM and TRM DTC IM drives for low speed operation and insensitive to stator resistance. The performance of the drives has been investigated for low speed operation using simulations and experimental work. They have shown excellent performance.
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Jacmenovic, Dennis, and dennis_jacman@yahoo com au. "Optimisation of Active Microstrip Patch Antennas." RMIT University. Electrical and Computer Engineering, 2004. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20060307.144507.
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This thesis presents a study of impedance optimisation of active microstrip patch antennas to multiple frequency points. A single layered aperture coupled microstrip patch antenna has been optimised to match the source reflection coefficient of a transistor in designing an active antenna. The active aperture coupled microstrip patch antenna was optimised to satisfy Global Positioning System (GPS) frequency specifications. A rudimentary aperture coupled microstrip patch antenna consists of a rectangular antenna element etched on the top surface of two dielectric substrates. The substrates are separated by a ground plane and a microstrip feed is etched on the bottom surface. A rectangular aperture in the ground plane provides coupling between the feed and the antenna element. This type of antenna, which conveniently isolates any circuit at the feed from the antenna element, is suitable for integrated circuit design and is simple to fabricate. An active antenna design directly couples an antenna to an active device, therefore saving real estate and power. This thesis focuses on designing an aperture coupled patch antenna directly coupled to a low noise amplifier as part of the front end of a GPS receiver. In this work an in-house software package, dubbed ACP by its creator Dr Rod Waterhouse, for calculating aperture coupled microstrip patch antenna performance parameters was linked to HP-EEsof, a microwave computer aided design and simulation package by Hewlett-Packard. An ANSI C module in HP-EEsof was written to bind the two packages. This process affords the client the benefit of powerful analysis tools offered in HP-EEsof and the fast analysis of ACP for seamless system design. Moreover, the optimisation algorithms in HP-EEsof were employed to investigate which algorithms are best suited for optimising patch antennas. The active antenna design presented in this study evades an input matching network, which is accomplished by designing the antenna to represent the desired source termination of a transistor. It has been demonstrated that a dual-band microstrip patch antenna can be successfully designed to match the source reflection coefficient, avoiding the need to insert a matching network. Maximum power transfer in electrical circuits is accomplished by matching the impedance between entities, which is generally acheived with the use of a matching network. Passive matching networks employed in amplifier design generally consist of discrete components up to the low GHz frequency range or distributed elements at greater frequencies. The source termination for a low noise amplifier will greatly influence its noise, gain and linearity which is controlled by designing a suitable input matching network. Ten diverse search methods offered in HP-EEsof were used to optimise an active aperture coupled microstrip patch antenna. This study has shown that the algorithms based on the randomised search techniques and the Genetic algorithm provide the most robust performance. The optimisation results were used to design an active dual-band antenna.
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Kurtdere, Ahmet Gokhan. "Efficient Solution Of Optimization Problems With Constraints And/or Cost Functions Expensive To Evaluate." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12611342/index.pdf.
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There are many optimization problems motivated by engineering applications, whose constraints and/or cost functions are computationally expensive to evaluate. What is more derivative information is usually not available or available at a considerable cost. For that reason, classical optimization methods, based on derivatives, are not applicable. This study presents a framework based on available methods in literature to overcome this important problem. First, a penalized model is constructed where the violation of the constraints are added to the cost function. The model is optimized with help of stochastic approximation algorithms until a point satisfying the constraints is obtained. Then, a sample point set satisfying the constraints is obtained by taking advantage of direct search algorithms based sampling strategies. In this context, two search direction estimation methods, convex hull based and estimated radius of curvature of the sample point set based methods can be applicable. Point set is used to create a barrier which imposes a large cost for points near to the boundary. The aim is to obtain convergence to local optima using the most promising direction with help of direct search methods. As regards to the evaluation of the cost function there are two directions to follow: a-) Gradient-based methods, b-) Non-gradient methods. In gradient-based methods, the gradient is approximated using the so-called stochastic approximation algorithms. In the latter case, direct search algorithms based sampling strategy is realized. This study is concluded by using all these ideas in the solution of complicated test problems where the cost and the constraint functions are costly to evaluate.
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Tanzke, Anja [Verfasser], Allen [Akademischer Betreuer] [Gutachter] Caldwell, and Stefan [Gutachter] Schönert. "Low-Threshold Detectors for Low-Mass Direct Dark Matter Search with CRESST-III / Anja Tanzke ; Gutachter: Allen Caldwell, Stefan Schönert ; Betreuer: Allen Caldwell." München : Universitätsbibliothek der TU München, 2017. http://d-nb.info/1125627115/34.
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Colberg, Tilmann. "Measurement of the Branching Fraction and Search for Direct CP-Violation in the Radiative Decay B to K*Gamma with the BABAR Detector." [S.l. : s.n.], 2002. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB9918569.
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Sivers, Moritz von [Verfasser], Lothar [Akademischer Betreuer] Oberauer, and Hubert [Akademischer Betreuer] Kroha. "Scintillating CaWO4 Crystals for the Direct Dark Matter Search Experiments CRESST and EURECA / Moritz von Sivers. Gutachter: Lothar Oberauer ; Hubert Kroha. Betreuer: Lothar Oberauer." München : Universitätsbibliothek der TU München, 2014. http://d-nb.info/1054753040/34.
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Blount, Nicholas L. "A search for direct and radiative decays of the B⁰ meson to invisible final state using a hadronic tagging method at the BABAR detector /." Connect to title online (Scholars' Bank) Connect to title online (ProQuest), 2008. http://hdl.handle.net/1794/9171.
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Thesis (Ph. D.)--University of Oregon, 2008.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 117-118). Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.
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Münster, Andrea Ruth [Verfasser], Stefan [Akademischer Betreuer] [Gutachter] Schönert, and Shawn [Gutachter] Bishop. "High-Purity CaWO4 Single Crystals for Direct Dark Matter Search with the CRESST Experiment / Andrea Ruth Münster ; Gutachter: Stefan Schönert, Shawn Bishop ; Betreuer: Stefan Schönert." München : Universitätsbibliothek der TU München, 2017. http://d-nb.info/1147968233/34.
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Blount, Nicholas L. 1979. "A search for direct and radiative decays of the neutral B meson to invisible final states using a hadronic tagging method at the BABAR detector." Thesis, University of Oregon, 2008. http://hdl.handle.net/1794/9171.
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xii, 118 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.This dissertation describes a search for the decays B 0 [arrow right] invisible and B 0 [arrow right] invisible+γ, where invisible refers to a final state consisting of long lived particles with a low cross-section for interaction with matter, leading to a low probability of detection in typical particle detectors. While the branching fractions for these decays predicted by the Standard Model are far below what could be feasably measured by current experiments, new physics such as right-handed neutrinos propagating in large extra space-time dimensions or light R-parity violating neutralinos in supersymmetry could greatly enhance the branching fractions. The decays are searched for in data corresponding to 423.5 fb -1 integrated luminosity produced at the Υ(4 S ) resonance collected with the BABAR detector at the PEP-II B factory, corresponding to 2.30 × 10 8 B 0 B¯ 0 pairs. Using those events that contain a hadronically reconstructed neutral B meson, evidence for the signal decays is sought in the remainder of the event. In (5.00 ± 0.02) × 10 5 events with a fully reconstructed neutral B meson, a total of 39 events consistent with the B 0 [arrow right] invisible decay mode are seen in data with an expected background of 28.5 ± 7.8(stat.)±9.2(syst.) events, and 8 events consistent with the B 0 [arrow right] invisible+γ decay mode are seen in data mode with an expected background of 14.1 ± 5.5(stat.)±8.1(syst.) events, from which upper limits of [Special characters omitted.] ( B 0 [arrow right] invisible) < 11.7 × 10 -5 and of [Special characters omitted.] ( B 0 [arrow right] invisible+γ) < 4.3 × 10 -5 at the 90% confidence level are obtained.
Adviser: David Strom
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Hnízdilová, Petra. "Porovnání metod získávání zaměstnanců v podmínkách českého trhu práce. Headhunting versus recruitment." Master's thesis, Vysoká škola ekonomická v Praze, 2014. http://www.nusl.cz/ntk/nusl-264327.
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The theoretical part describes the field of personnel policy, focusing on the issue of finding employees. The Master´s thesis is focused on the work headhunting companies in comparison with the work of employment agencies. The aim of my work is verify possibility to determine the situations in which it is more efficient to use the method of direct systematic search and when the classical method of recruitment. In my work I analyze not only the management of human resources but also the functioning of the personnel departments of companies with reference to personal marketing. The Master´s thesis is also supplemented with practical knowledge and the final section describe the outcome of the survey