• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 52
  • 16
  • 14
  • 5
  • 5
  • 3
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 113
  • 12
  • 10
  • 9
  • 9
  • 9
  • 8
  • 7
  • 7
  • 7
  • 7
  • 6
  • 6
  • 6
  • 6
  • 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.
31

Probing the proton structure through deep virtual Compton scattering at COMPASS, CERN / Etude de la structure interne du proton par diffusion Compton virtuelle à COMPASS, CERN

Vidon, Antoine 01 October 2019 (has links)
La diffusion Compton virtuelle (DVCS) est un processus idéal pour étudier la structure interne du proton. Cette réaction exclusive permet d’accéder aux distributions de partons généralisées (GPDs) qui encodent les corrélations entre impulsion longitudinale et position transverse des partons à l’intérieur du proton. Le DVCS consiste à sonder le proton au moyen d’un photon virtuel de grande virtualité pour produire dans l’état final un unique photon réel de grande énergie tout en laissant le proton intact.A COMPASS au CERN, où deux années de données ont été collectées en 2016 et 2017 afin de mesurer la section efficace du processus DVCS, le photon virtuel est issu de la diffusion d’un faisceau de μ⁺ ou de μ⁻ polarisé de 160 GeV sur une cible d’hydrogène liquide. Toutes les particules de la réaction sont détectées dans l’expérience : le muon incident est détecté dans le télescope du faisceau, le muon diffracté et le photon réel sont détectés à l’avant dans le spectromètre et les trois calorimètres tandis que le proton de recul est détecté dans un détecteur de temps de vol placé autour de la cible.Je présente dans cette thèse l’état de l’analyse du processus DVCS sur les données collectées à COMPASS en 2016. Après un rappel du contexte théorique et expérimental, je décris l’expérience COMPASS. Je détaille ensuite mon travail de calibration du détecteur de proton de recul et de détermination de la position exacte de la cible de 2 cm de diamètre et 2.5 m de longueur. J’étudie dans la partie suivante la sélection de différents canaux de physique permettant de contrôler de manière systématique la qualité des détecteurs : la diffusion profondément inélastique (DIS) qui implique le télescope du faisceau et le spectromètre, la production exclusive de ρ⁰ qui inclut aussi le détecteur de temps de vol ; puis je présente la première analyse de la production exclusive de photons uniques qui implique en plus les trois calorimètres. Dans une dernière partie j’évoque les étapes nécessaires à la détermination de la section efficace du DVCS à partir de cette sélection, et je présente les premiers résultats issus de la simulation associée. / Virtual Compton Scattering (DVCS) is an ideal process to study the internal structure of proton. This exclusive reaction provides access to generalised parton distributions (GPDs), which encode the correlations between longitudinal momentum and transverse position of partons inside the proton. DVCS consists in probing a proton with a virtual photon of high virtuality, in order to produce a single high energy real photon while leaving the proton intact in the final state.At COMPASS at CERN, where two years of data were collected in 2016 and 2017 to measure the DVCS cross section, the virtual photon is produced by scattering of a 160 GeV polarised μ⁺ or μ⁻ beam on a liquid hydrogen target. All particles are detected in the experiment: the incident muon is detected in the beam telescope, the diffracted muon and the real photon are detected in the forward spectrometer and the three calorimeters, while the recoil proton is detected in a time-of-flight detector positioned around the target.In this thesis I present the state of the analysis of the DVCS process on the data collected at COMPASS in 2016. After a reminder of the theoretical and experimental context, I describe the COMPASS experiment. I then detail my work on calibrating the recoil proton detector and determining the the exact position of the 2 cm diameter and 2.5 m long target. In the next section, I study the selection of different physics channels used to systematically control detector quality: Deep Inelastic Scattering (DIS) which involves the beam-telescope and spectrometer, exclusive ρ⁰ production which requires the addition of the time-of-flight detector and I follow with the first analysis of the exclusive single photon production which depends as well on the calorimetres quality. In a last part, I discuss the necessary steps needed to extract the DVCS cross-section out of this event selection, and present the first results associated to the Monte-Carlo simulation.
32

The desert ant's celestial compass system

Lebhardt, Fleur 18 November 2015 (has links)
Die Wüstenameise, Cataglyphis, orientiert sich vor allem mittels Wegintegration. Über einen Heimvektor, den sie aus Distanz und Richtung einzelner Wegabschnitte berechnet, kann sie auf dem kürzesten Weg zu ihrem Ausgangspunkt zurückkehren. Zur Bestimmung der zurückgelegten Strecken verwendet sie einen Schrittintegrator. Die Laufrichtung wird hauptsächlich über Himmelsinformationen (Polarisationsmuster, Sonnenstand und Spektral- und Intensitätsgradienten) definiert. In dieser Arbeit über die Orientierungsfähigkeit von Cataglyphis fortis wird die Rolle des Polarisationskompasses bei der Bestimmung der Laufrichtung untersucht. In verschiedenen Versuchen wurden der Polarisationskompass der Ameise mit Hilfe eines Polarisationsfilters gezielt manipuliert und künstliche Konfliktsituationen erzeugt. Die Richtungsbestimmung wurde vom Polarisationskompass dominiert, wenn allein die Information des Polarisationskompass und idiothetische Richtungsinformation zur Verfügung standen. Erfuhren die Ameise widersprüchliche Informationen von Sonnen- und Polarisationskompass, berechneten sie eine mittlere Heimlaufrichtung, was eine gemeinsame neuronale Verarbeitung der beiden Signale voraussetzt. Diese These wurde durch Transferexperimente gestützt. In einer weiteren Versuchsreihe wurde die Wahrnehmung des Polarisationsmusters durch direkte Manipulation der entsprechenden Region (DRA) im Ameisenauge untersucht. Standen der Ameise in beiden Augen die frontale oder caudale DRA zur Verfügung führte dies zu einem deutlichen Orientierungsverlust. Die intakte DRA eines Auges erlaubte eine zielgerichtete Fortbewegung, die jedoch von der Erwartungsrichtung abwich. Zusammenfassend zeigen die Ergebnisse der vorliegenden Studie, dass der Polarisationskompass die präziseste Richtungsinformation liefert und den Himmelskompass der Wüstenameise dominiert. / The desert ant, Cataglyphis, navigates predominantly by means of path integration. The information about the distance and direction of individual path segments is integrated into a home vector, which allows the ant to return to the starting point on the shortest way. The distances covered are determined by a stride integrator. The heading direction is inferred mainly via celestial cues: the sky’s polarization pattern, the position of the sun, and the spectral and intensity gradient. This thesis focuses generally on the orientation abilities of Cataglyphis fortis and particularly on the role of the polarization compass to determine the heading direction. In the experiments, the ant’s polarization compass was selectively manipulated using a polarization filter and artificial cue conflict situations were created. The ants relied exclusively on the polarization compass to determine their heading direction if only idiothetic information and information from the polarization compass were available. When the ants experienced contradicting information detected via the sun and the polarization compass systems, an intermediate homing direction was calculated, suggesting a combined neural processing of both signals. This statement was supported by transfer experiments. In a further series of experiments, the input part of the polarization compass was manipulated. Particular regions of the ant’s eye (DRA) that detect polarized light were occluded. Ants with only the frontal or caudal parts of the DRA became disoriented, whereas ants with the entire DRA of one eye were able to perform more precise paths, although deviated from the expected direction. Overall, the results from this thesis suggest that the polarization compass provides the most accurate directional information and dominates the celestial compass system of the desert ant.
33

COMMUNICATION AND HIGH QUALITY COACH-ATHLETE RELATIONSHIP : THE MODERATING ROLE OF ATHLETE ATTACHMENT

Gisslén, Sofie, Sundström, Elin January 2019 (has links)
This cross-sectional study presented two aims: 1) to examine whether associations could be found between athletes’ use of communication strategies conflict management, openness and support, and athletes’ perceptions of coach-athlete relationship quality, and 2) to examine whether athletes’ attachment style (secure, anxious-ambivalent or avoidant) would act as a moderator for this association. A sample of 396 athletes (males = 183, females = 210) whose age ranged from 15 to 60 years (mean age = 19.17, SD = 4.59 years). The sample was recruited from a variety of both individual and team sports. In order to participate, athletes responded a questionnaire, online or in paper version. Statistical analyses were performed in IBM SPSS 24 and Amos 24, and by using Structural Equation Modelling (SEM). The results confirmed associations between athletes’ use of the selected communication strategies and their perceptions of the coach-athlete relationship quality. Regarding moderating effects, athletes’ attachment style was shown to have a significant moderation effect on a majority of the found associations. Suggestions for future research is to examine more of the communication strategies presented in the COMPASS model, in order to strengthen the model’s practical use. Also, longitudinal studies would complement these findings, as well as qualitative research for a deepened understanding of the communication strategies. / Denna tvärsnittsstudie hade två syften: 1) att undersöka om det fanns ett samband mellan idrottares användande av kommunikationsstrategierna konflikthantering, öppenhet och stöd och deras skattning av kvaliteten på relationen till tränaren, samt 2) att undersöka om idrottares anknytningsstil (trygg, ambivalent och undvikande) hade påverkan det sambandet. 396 idrottare (män = 183, kvinnor = 210 ) i åldrarna 15-60 år (medelålder = 19.17, SD = 4.59 år). Urvalet rekryterades från både individ- och lagidrott. För att delta fyllde idrottarna i ett formulär, i webb- eller pappersform. Statistiska analyser utfördes i IBM SPSS och Amos 24, samt genom Structural Equation Modelling (SEM). Resultaten bekräftade samband mellan idrottares användande av de valda kommunikationsstrategierna och deras skattning av kvaliteten på tränar-idrottare-relationen. Idrottarnas anknytningsstil visade sig ha en statistiskt signifikant modererande effekt på de funna sambanden. Förslag för vidare forskning är att undersöka fler av de kommunikationsstrategier som presenteras i COMPASS-modellen, för att kunna stärka modellens praktiska användning. Dessutom skulle longitudinella studier kunna komplettera dessa resultat, liksom kvalitativ forskning för att få en djupare förståelse för kommunikationsstrategierna.
34

Multipla loggar för ökad programförståelse : Hur multipla loggar kan bidra till programutveckling och programförståelse / Multiple traces for increased program comprehension : How multiple traces can contribute to software development and program comprehension

Hejderup, Jacob January 2018 (has links)
För att utveckla eller underhålla mjukvara krävs en viss nivå av programförståelse. För att underlätta denna förståelse används olika typer av verktyg. Denna studie fokuserar på två olika verktyg som använder sig av dynamisk analys: enkla och multipla loggar. Studiens syfte är att undersöka om multipla loggar kan bidra till en ökad programförståelse vid programutveckling. Eclipse är en utvecklingsmiljö som används för att visa programmets källkod. Trace Compass är ett verktyg som används för att inspektera loggar. Denna studie utfördes i två moment: experiment och intervjuer. Experimentet bestod av 10 typiska förståelseuppgifter i ett program-utvecklingssammanhang. Efter experimentet utfördes en intervju med samtliga deltagare.  Resultatet av undersökningen blev att multipla loggar skulle kunna vara lämpligare att använda vid problem som var relaterade till två eller fler komponenter i ett system.  En av begränsningarna i denna studie var att studien hade för få deltagare för ett generellt ställningstagande. / To develop or maintain a piece of code requires a certain level of comprehension of the developed or maintained software itself. To achieve this goal the developer uses a set of different tools. This report will focus on two types of debug tools: single trace and multiple traces. The purpose of the study is to examine how multiple traces can contribute to an improved program comprehension. The study was carried out through experiments and interviews. The experiment consisted of 10 typical comprehension tasks in a development context. Eclipse and Trace Compass were used to display the logs. Eclipse is a development environment that shows the source code. Trace Compass is a tool for inspecting traces.  After the experiment, an interview was carried out with the subjects of the experiment. The results of this study indicated that multiple traces could have an advantage over a single trace when the task is to understand the interactions between code components in a software system. One of the limitations of the study was due to the limited number of subjects taken part in the study and cannot be used to draw a more general conclusion.
35

Trace Visualization with Java Pathfinder using Theia Trace Viewer

Besseling, Johan January 2022 (has links)
Java Pathfinder (JPF) is a tool to debug Java-based software running multiple threads or processes, with a textual output that be may hard to understand. Recent development introduced the possibility to generate a trace from JPF and visualize it in Trace Compass (TC), a general-purpose trace viewing application. Due to difficulties in maintaining and developing new features for TC, Theia Trace Viewer (TTV) has emerged as the replacement for TC. TTV is a browser-based trace viewer and makes it possible to visualize traces without any download or installation by the user. In this work, we migrate the existing functionality of JPF Trace from TC to TTV and conduct a user study on how TTV supports users analyzing JPF traces. Our results show that TTV is a good start and has great potential, but requires further development before replacing JPF results in textual format. / Java Pathfinder (JPF) är ett verktyg för att hitta fel i Javabaserad mjukvara som exekverar med flera trådar eller processer, där resultat skickas ut som text och kan vara svårt att förstå. Nyligen utvecklades möjligheten att generera ett spår och visualisera i Trace Compass (TC), ett program som kan visualisera olika typer av spårformat. På grund av svårigheter med att underhålla och utveckla nya funktioner för TC, så har Theia Trace Viewer (TTV) vuxit fram som ersättaren för TC. TTV är en webbläsare-baserad traceviewer, där det är möjligt att visualisera spår utan att användaren behöver ladda ner eller installera något. I detta arbete, migrerar vi den befintliga funktionaliteten för JPF Trace i TC till TTV och genomför en användarstudie för att ta reda på hur TTV hjälper användare analysera JPF spår. Vårat resultat visar att TTV är en bra början med god potential, men behöver utvecklas vidare innan det går att ersätta JPF resultat i textformat.
36

Optimisation of Expected Return from a Stock Portfolio - A Knapsack Problem / Optimering av förväntad avkastning från en aktieportfölj - Ett kappsäcksproblem

Hörnfeldt, Philip, Svensson, Erik January 2023 (has links)
In recent years, sustainable investments have risen in popularity as a result of climate change. However, there is a shortage of reliable tools to aid investors in allocating their funds more sustainably, while still ensuring maximum profitability. Another issue introduced in connection with climate change is greenwashing - companies falsely marketing themselves as sustainable without working on minimizing their environmental impact. The aim of the project is to solve the aforementioned problems and investigate the cost of deterring from profitability for sustainability.  This paper explores if there is a way to allocate a stock portfolio to ensure optimally while taking sustainability into account. The method features predicting the future revenue of stocks, evaluating and quantifying sustainability from companies, and optimizing the portfolio in order to find the optimal set of stocks. The optimization is performed using dynamic programming by treating the problem as a Knapsack Problem. The algorithm is evaluated for two investor profiles - with focus on profitability and with focus on sustainability. The results concluded in a set of shares following a stationary distribution for both investment profiles. Consequently, it is reasoned that Dynamic Programming is a suitable method of optimization within the scope of the thesis however it is also reasoned that improvements can be made to include more sophisticated optimization methods. The cost of selecting the more sustainable option is determined to adhere to a linear relation for all budget levels. / Under de senaste åren har intresset ökat för hållbara investering till följd av klimatkrisen. Den snabba förändringen har emellertid medfört att det inte finns tillförlitliga hjälpverktyg tillgängliga för investerare att fördela sin tillgångar. Ännu ett problem som har dykt upp i samband med klimatkrisen är greenwashing - att företag marknadsför sig som miljövänliga, utan att försöka minska sin klimatpåverkan. Projektets mål är att försöka lösa dem nämnda problemen, samt att undersöka förlusten av att prioritera hållbarhet före lönsamhet.  Syftet med denna uppsats är att utforska möjligheterna med att optimera en aktieportfölj när hållbarhet betraktas som värderingsfaktor. Metoden omfattar att bestämma aktiernas förväntade framtida avkastning, utvärdering och modellering av företags hållbarhetsarbete samt optimering av portföljen. I detta projekt tillämpades dynamisk programmering som optimeringsmetod. Algoritmen utvärderas för två investerings profiler - en som prioriterar lönsamhet och en som prioriterar hållbarhet. Undersökningsresultaten visar att den optimala portföljen följer en stationär fördelning i båda fallen. Följaktligen dras slutsatsen att dynamisk programmering är en tillräckligt bra optimeringsmetod inom undersökningens avgränsningar men att det i framtiden går att införa förbättringar för att ta hänsyn till mer sofistikerade optimeringsmetoder. Det visas även att kostnaden för frångå lönsamhet beskrivs av ett linjärt samband på ala budgetnivåer.
37

Analysis of a Combined GLONASS/Compass-I Navigation Algorithm

Peng, Song, Xiao-yu, Chen, Jian-zhong, Qi 10 1900 (has links)
ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, Nevada / Compass-I system is China has built satellite navigation system. It's a kind of regional position system according to the double-star position principle. Commonly, Compass-I system need adopt active position, in the paper several passive position methods are put forward. A combination navigation mode based on GLONASS and Compass-I passive navigation is proposed in this paper. The differences of coordinates and time systems between those two navigation systems are analyzed. User position is calculated by least squares method. Combination Navigation Algorithm can improve visible satellite constellation structure and positioning precision so as to ensure the reliability and continuity of positioning result.
38

How is an ant navigation algorithm affected by visual parameters and ego-motion?

Ardin, Paul Björn January 2017 (has links)
Ants typically use path integration and vision for navigation when the environment precludes the use of pheromones for trails. Recent simulations have been able to accurately mimic the retinotopic navigation behaviour of these ants using simple models of movement and memory of unprocessed visual images. Naturally it is interesting to test these navigation algorithms in more realistic circumstances, particularly with actual route data from the ant, in an accurate facsimile of the ant world and with visual input that draws on the characteristics of the animal. While increasing the complexity of the visual processing to include skyline extraction, inhomogeneous sampling and motion processing was conjectured to improve the performance of the simulations, the reverse appears to be the case. Examining closely the assumptions about motion, analysis of ants in the field shows that they experience considerable displacement of the head which when applied to the simulation leads to significant degradation in performance. The family of simulations rely upon continuous visual monitoring of the scene to determine heading and it was decided to test whether the animals were similarly dependent on this input. A field study demonstrated that ants with only visual navigation cues can return the nest when largely facing away from the direction of travel (moving backwards) and so it appears that ant visual navigation is not a process of continuous retinotopic image matching. We conclude ants may use vision to determine an initial heading by image matching and then continue to follow this direction using their celestial compass, or they may use a rotationally invariant form of the visual world for continuous course correction.
39

Jogos lógicos no Ensino Fundamental

Rosa, Leandro Viana da January 2016 (has links)
Esta pesquisa se dedicou à introdução dos jogos lógicos na sala de aula, em específico, ela busca a investigação das dificuldades encontradas pelos alunos com os diferentes estilos de jogos apresentados e quais são os raciocínios lógicos utilizados para a resolução dos problemas propostos. Buscamos os benefícios que estes jogos podem trazer para o ensino e a aprendizagem na sala de aula. Aliado a isso também trabalhamos a parte geométrica dos tabuleiros, e com isso os alunos utilizaram como ferramentas a régua e o compasso para a construção dos tabuleiros apresentados.. Para tanto, a metodologia de pesquisa escolhida foi o Estudo de Caso, de acordo com Fiorentini e Lorenzato (2006), Ventura (2007) e Gil (2002). O referencial teórico é baseado nos trabalhos de Macedo (2007), Grando (2011), Skovsmose (2000), Huizinga (2000), Kishimoto (2006), Zuin (2001), bem como os PCNs e outros artigos/livros relacionados aos jogos lógicos e as construções geométricas com a régua e o compasso. As atividades foram desenvolvidas com uma turma do 9º ano do Ensino Fundamental de em uma Escola Municipal de Porto Alegre, no ano de 2015. Em especial sugerimos que é possível a inserção desses materiais a fim de serem usados como ferramentas de auxílio no ensino aprendizagem de matemática contribuindo positivamente para a formação dos alunos. Os registros coletados no estudo de caso possibilitaram a validação da proposta. / The present research has focused on the introduction of the logical games in the class. It aims to pin point difficulties presented by the students on the different styles of games proposed and a logical ratiocination is required to solve the tasks proposed. The benefits of the games along with the teaching and learning in the classroom was the goal. Additionally, the geometric segment of board games have been investigated and students used tools as ruler and compass to the construction of the boards presented. Therefore, the chosen researching methodology was the Case Study, according to Fiorentini e Lorenzato (2006), Ventura (2007) e Gil (2002). The theoretical referential is based on Works from Macedo (2007), Grando (2011), Skovsmose (2000), Huizinga (2000), Kishimoto (2006), Zuin (2001), along with the PCNs and others articles/books related to logical games and geometric constructions with a ruler and a compass. The activities were performed by a 9th grade group of the Elementary School in a Municipal School in Porto Alegre, in 2015. We showed in particular that is possible the insertion of these materials in order to be used as a sustenance tool on Mathematics Learning contributing positively to students formation. The data collected in the case study enabled the authentication of the proposal.
40

Construções geométricas e os problemas de apolônio / Geometric construction, ruler, compass, apollonius' problem

Vieira, Mariana Araújo 22 March 2013 (has links)
Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2014-09-23T12:11:15Z No. of bitstreams: 2 Vieira, Mariana Araujo.pdf: 2336552 bytes, checksum: a3cdecc71ec9fe00f17a840ededdcce2 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2014-09-23T15:10:25Z (GMT) No. of bitstreams: 2 Vieira, Mariana Araujo.pdf: 2336552 bytes, checksum: a3cdecc71ec9fe00f17a840ededdcce2 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-09-23T15:10:25Z (GMT). No. of bitstreams: 2 Vieira, Mariana Araujo.pdf: 2336552 bytes, checksum: a3cdecc71ec9fe00f17a840ededdcce2 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2013-03-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This paper aims to present the main problems of Apollonius.... / Este trabalho tem como objetivo principal apresentar os dez problemas de Apôlonio....

Page generated in 0.0225 seconds