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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
261

Procedurell generering av racerbanor genom Voronoi diagram : Procedurellt genererade Formel 1 racerbanor genom modifierade Voronoi diagram och self-avoiding random walk / Procedural generation of race tracks using Voronoi diagrams : Procedurally generated Formula 1 circuits using modified Voronoi diagrams and self-avoiding random walk

Petersson, Filip, Windhede, Daniel January 2021 (has links)
Arbetet undersökte om det är möjligt att procedurellt generera giltiga och underhållande racerbanor för Formel 1 genom användandet av Voronoi diagram och self-avoiding random walk. En procedurell algoritm skapades och två enkäter konstruerades för att undersöka denna algoritms underhållningsvärde. Dessa enkäter distribuerades till kunniga individer inom racinggenren. Både algoritmen som helhet och dess dynamiska parametrar undersöktes. Det fastställdes att det är möjligt att procedurellt generera Formel 1 racerbanor som är underhållande med detta tillvägagångssätt. Vidare visar resultatet att en stor del av svarspersonerna finner artefaktens procedurella racerbanor underhållande, även i kontrast till riktiga racerbanor. Gynnsamma värden för artefaktens dynamiska parametrar i mån av ökad underhållning har också fastställts. En mer omfattande algoritm kan skapas utifrån detta arbete som tar hänsyn till exempelvis höjdskillnader och camber. Framtida arbeten kan då undersöka dessa delar av en racerbanas underhållningsvärde. Algoritmen kan även jämföras med andra procedurella metoder inom racing och andra spel. / <p>Det finns övrigt digitalt material (t.ex. film-, bild- eller ljudfiler) eller modeller/artefakter tillhörande examensarbetet som ska skickas till arkivet.</p>
262

Non-Equilibrium Disordering Processes In binary Systems Due to an Active Agent

Triampo, Wannapong 11 April 2001 (has links)
In this thesis, we study the kinetic disordering of systems interacting with an agent or a walker. Our studies divide naturally into two classes: for the first, the dynamics of the walker conserves the total magnetization of the system, for the second, it does not. These distinct dynamics are investigated in part I and II respectively. In part I, we investigate the disordering of an initially phase-segregated binary alloy due to a highly mobile vacancy which exchanges with the alloy atoms. This dynamics clearly conserves the total magnetization. We distinguish three versions of dynamic rules for the vacancy motion, namely a pure random walk , an "active" and a biased walk. For the random walk case, we review and reproduce earlier work by Z. Toroczkai et. al., [9] which will serve as our base-line. To test the robustness of these findings and to make our model more accessible to experimental studies, we investigated the effects of finite temperatures ("active walks") as well as external fields (biased walks). To monitor the disordering process, we define a suitable disorder parameter, namely the number of broken bonds, which we study as a function of time, system size and vacancy number. Using Monte Carlo simulations and a coarse-grained field theory, we observe that the disordering process exhibits three well separated temporal regimes. We show that the later stages exhibit dynamic scaling, characterized by a set of exponents and scaling functions. For the random and the biased case, these exponents and scaling functions are computed analytically in excellent agreement with the simulation results. The exponents are remarkably universal. We conclude this part with some comments on the early stage, the interfacial roughness and other related features. In part II, we introduce a model of binary data corruption induced by a Brownian agent or random walker. Here, the magnetization is not conserved, being related to the density of corrupted bits ρ. Using both continuum theory and computer simulations, we study the average density of corrupted bits, and the associated density-density correlation function, as well as several other related quantities. In the second half, we extend our investigations in three main directions which allow us to make closer contact with real binary systems. These are i) a detailed analysis of two dimensions, ii) the case of competing agents, and iii) the cases of asymmetric and quenched random couplings. Our analytic results are in good agreement with simulation results. The remarkable finding of this study is the robustness of the phenomenological model which provides us with the tool, continuum theory, to understand the nature of such a simple model. / Ph. D.
263

Pièges et vieillissement pour les marches aléatoires sur des environnements aléatoires hautement irréguliers : phénoménologie et étude de cas

Davignon, Élise 11 1900 (has links)
Nous présentons d’abord une introduction au sujet des marches aléatoires en milieux aléatoires. Nous nous penchons en particulier sur les phénomènes de ralentissement, et plus précisément sur la propriété de vieillissement qu’exhibent plusieurs de ces systèmes lorsque les paramètres sont tels qu’ils conduisent l’environnement aléatoire à produire fréquemment des « pièges », soient des structures qui retiennent la marche aléatoire dans la même région de l’environnement pour de longues durées de temps. Nous illustrons ces notions à l’aide de résultats connus pour deux modèles. Nous présentons par la suite une preuve pour une propriété de vieillissement dans le cas de la marche aléatoire biaisée sur les conductances aléatoires à queues lourdes dans la grille infinie hyper-cubique à d dimensions, qui est le sujet d’un article en attente de publication. / We first present an introduction to the topic of random walks on random environments (RWRE). In particular, we look at slow-down phenomena and, more specifically, ageing properties exhibited by multiple such systems when parameters are chosen such that the random environment frequently produces large “traps”: structures that hold up the progress of the random walk by keeping it in the same region of the environment for long periods of time. We illustrate these behaviours by presenting known results for two such models. We then present a proof for an ageing property in the case of the biased random walk on heavy-tailed random conductances in the infinite hyper-cubic lattice in d dimensions; this is the subject of a research article pending publication.
264

Exective Exodus : An Empirical Exploration of CEO Resignations and Stock Price Dynamics in Nordic Large Cap Companies

Vanneback, Agust, Kaing, Max January 2024 (has links)
There has always been competition among hedge funds, mutual funds, and other types of investors to perform better than index, meaning, creating alpha. How can you create alpha? Are there any patterns to follow? Any trends? There are many questions one may ask in order to find patterns that are creating. The purpose of this study is to see how CEO departures affect equity value in the short- medium- and long term and its comparison to indices. This study has collected data from a majority of publicly traded Nordiccompanies with a market capitalisation of over 10 billion Swedish crowns. The collected data has been collected within the last 20 years (2003-2023) with market-adjusted return, market capitalisation, volume, and CEO tenure being the prominent variables analysed.As CEOs have the operative responsibility of a company, they thereby are at the top of the company and effectively guide the company towards its goals. The changes in CEOs could thereby be of interest to investors as there is potential for larger structural changes when a new CEO is appointed. Applying this to its equity value, there is potential formispricing. Using mainly Fama’s and Malkiel’s research on the Efficient Market Hypothesis (EMH) and Random Walk as the theoretical framework there are different ways in which equity price could move. EMH states that all markets are efficient by the equity representing all available information. Random Walk instead states that equity price moves randomly and cannot be predicted in accordance with historical movements. The empirical results showed that there were no statistically significant findings in our employed regression analysis. However, on average, the descriptive statistics show thatthe market-adjusted return for a company with a CEO departure is negative compared to its comparable index. The intraday MAR highly deviate from 1 day until 1 quarter and thereafter the deviation becomes less. The conclusion could be drawn that EMH might be contradicted in the short term but holds long term. It is also difficult to deny the theory of random walks in equities.
265

Finansmarknadens reaktioner på naturkatastrofer förorsakade av enskilda bolag : En eventstudie av katastrofen i den Mexikanska golfen 2010

Moya, Juan, Östlund, Johannes January 2010 (has links)
Bakgrund: Den 20:e april 2010 inträffade en explosion på BP:s oljeplattform Deepwater Horizon i Mexikanska Golfen. Explosionen uppstod på grund av metangas som under högt tryck expanderade på plattformen och sedan antändes. Detta ledde senare till att oljeplattformen sjönk och ett stort okontrollerat oljeläckage uppstod på cirka 1500 meters djup.          Att explosionen i den mexikanska golfen har påverkat BP negativt och varit mycket kostsamt för företaget är uppenbart, börskursen hade som mest sjunkit med cirka 60 procent. Det kan vara intressant att undersöka huruvida denna katastrof, utlöst av en enskild aktör, också har spridit sig över till andra aktörer i Olja &amp; Gas sektorn. Syfte: Syftet med denna C-uppsats är att undersöka huruvida BP:s katastrof i den Mexikanska golfen har påverkat andra aktörer i samma sektor (Olja &amp; Gas sektorn). Metod: Sekundärdata presenteras som en kvantitativ ansats i form av siffror och för att kunna dra slutsatserna använder vi oss av en deduktiv ansats.I denna studie tillämpas en metodikteknik i form av en eventstudie, där beräkningar av den abnorma och förväntade avkastningen baseras på marknadsmodellen. Vidare har två hypoteser testats, där syftet med Hypotes I är att pröva huruvida information om händelsen i den Mexikanska Golfen påverkar andra företag i samma sektor som BP. Syftet med Hypotes II är att testa samma företag under samma period som Hypotes I, men undersöker förändring i tradingvolymerna istället för i aktiekurserna. Teori: Effektiva Marknadshypotesen, Random Walk och Flockbeteende Slutsatser: Dessa båda undersökningar d.v.s. Hypotes I och Hypotes II pekar starkt på slutsatsen att eventet har haft inverkat på övriga bolag i sektorn. Vi kunde vid en jämförelse med tidigare studier som genomförts på andra katastrofer, konstatera att skeendet har både likheter och skillnader. / Background: On the 20th April 2010, the BP oil platform Deepwater Horizon, situated in the Mexican Gulf, exploded. The explosion was caused by methanol gas that, under high pressure expanded and thereafter ignited. The platform submerged and caused a severe and uncontrollable oil leakage at 1500 meters depth.It is obvious that the explosion in the Mexican Gulf has impacted BP in a negative manner and cause BP large financial loss, the company shares had at its worst point depreciated by 60 percent. It may be of interest to investigate whether this catastrophe, caused by one independent party, also have affected other companies within the Oil and Gas industry. Purpose: The aim of this assignment is to investigate whether BP’s catastrophe in the Mexican Gulf has affected other companies within the same industry. (Oil and Gas) Methodology: Secondary data is presented as a quantitative approach in the shape of values and we use a deductive approach in order to draw the conclusions.The methodology used in this study is event study, in which calculation of the abnormal and expected revenue are based on the market model. We will test two types of hypothesis, where the aim of Hypothesis I is to test in which way information about the event in the Mexican Gulf affects other companies in the same industry as BP. The aim of Hypothesis II is to test the same companies during the same period as Hypothesis I, but with a focus on analyzing trading volume instead of the stock market value. Theory: Efficient Market Hypothesis, Random Walk and Herd Behavior Conclusion: Both investigations, i.e. Hypothesis I and Hypothesis II indicate that the event has had an impact on other companies in the same industry. We could, in a comparative analysis with earlier studies, based on other catastrophes, conclude that the event demonstrates similarities as well as differences.
266

Insynshandel - Vad är den kortsiktiga marknadsreaktionen? : En kvantitativ studie gällande insynspersoners möjlighet till att generera abnormal avkastning på First North Growth Market

Issa, Gabriel January 2021 (has links)
Insider trading has long been a controversial phenomenon in the financial world. Several studies have been conducted in the area where the studies have shown ambiguous results. In 2016, Finansipektionen amended the Insider Trading Act, namely that insiders need to report an insider transction within three days. Insiders ability to generate abnormal returns is considered to be in conflict with market efficiency.  This study examines insiders ability to generate abnormal returns on the First North Growth Market during the year 2020, where the sample consists of 47 observations. An eventstudy has been used to investigate the market reaction from the publication of insider trading. Multiple regression analysis has been applied to examine whether there is any difference in the abnormal return based on the position of the insider, the transactionsize of the insider tradingsize and the gender. The hypothesis tests have been answered with the help of a one-sided t-test and multiple regression analysis. A quantitative method and deductive approach have been used in the study where the researcher derived hypotheses based on previous research as well as theories such as the effective markethypothesis, the random-walk theory, the signalinghypothesis, behaviorbased financing and herdbehavior. This study shows that insiders generate abnormal returns during a short-term event window, but that there is no significant difference in the abnormal returns based on the insider’s position, transactionsize and gender. / Insynshandel har länge varit ett omdiskuterat fenomen inom finansvärlden. Flera studier har avlagts inom området som visat på tvetydiga resultat. År 2016 ändrade Finansinspektionen lagen om insynshandel, nämligen att insynspersoner behöver rapportera en insynstransaktion inom tre dagar. Insynspersoners möjlighet till att generera abnormal avkastning anses gå i strid mot marknadseffektiviteten. Denna studie undersöker insynspersoners möjlighet till att generera abnormal avkastning på First North Growth Market under året 2020 där urvalet består av 47 observationer. En eventstudie har använts för att undersöka marknadsreaktionen vid publiceringen av insynshandel. Multipel regressionsanalys har tillämpats för att undersöka ifall det finns någon skillnad i den abnormala avkastningen baserad på befattningen på insynspersonen, transaktionsstorleken av insynshandeln och kön. Hypotesprövningarna har besvarats med hjälp av ett ensidigt t-test samt multipel regressionsanalys. En kvantitativ metod och deduktiv ansats har använts i studien där forskaren härlett hypoteser utifrån tidigare forskning samt teorier som den effektiva marknadshypotesen, random-walk teorin, signaleringshypotesen, beteendebaserad finansiering och flockbeteende. Denna studie visar att insynspersoner genererar abnormal avkastning under ett kortsiktigt eventfönster men att det inte existerar någon signifikant skillnad på den abnormala avkastningen baserat på befattningen av insynspersonen, transaktionsstorleken och kön.
267

Analys av värdnationers aktiemarknadsreaktioner i samband med tillkännagivandet av mega-sportevenemang : En kvantitativ studie om tillkännagivandet av mega-sportevenemang med syfte att beskriva och analysera potentiella reaktionen på värdnationens aktiemarknad

Jonsson, Rasmus, Törnblom Ehrnst, Emil January 2024 (has links)
This study investigates the impact of mega-sporting event announcements on the host country's stock market. The analysis includes 34 events between 2000 and 2024, including the Olympic Games (Summer and Winter), the FIFA World Cup, and the UEFA European Championship. Employing a deductive approach grounded in existing theory and research, the study formulates hypotheses and utilizes an event study methodology to examine whether the announcements trigger abnormal returns in the host nation's stock market. T-tests are used to assess the statistical significance of the findings. The results provide limited evidence of market reactions to the announcements, with any potential effects occurring primarily before the official announcement, suggesting the possibility of information leakage or insider trading. No significant effects were found on the announcement day itself or on subsequent days. Furthermore, no statistically significant differences were found based on the economic size of the host nation or the type of event. However, the study did observe that FIFA World Cup announcements tend to generate slightly more volatile market reactions compared to the other events.
268

Étude de la performance d’un algorithme Metropolis-Hastings avec ajustement directionnel

Mireuta, Matei 08 1900 (has links)
Les méthodes de Monte Carlo par chaîne de Markov (MCMC) sont des outils très populaires pour l’échantillonnage de lois de probabilité complexes et/ou en grandes dimensions. Étant donné leur facilité d’application, ces méthodes sont largement répandues dans plusieurs communautés scientifiques et bien certainement en statistique, particulièrement en analyse bayésienne. Depuis l’apparition de la première méthode MCMC en 1953, le nombre de ces algorithmes a considérablement augmenté et ce sujet continue d’être une aire de recherche active. Un nouvel algorithme MCMC avec ajustement directionnel a été récemment développé par Bédard et al. (IJSS, 9 :2008) et certaines de ses propriétés restent partiellement méconnues. L’objectif de ce mémoire est de tenter d’établir l’impact d’un paramètre clé de cette méthode sur la performance globale de l’approche. Un second objectif est de comparer cet algorithme à d’autres méthodes MCMC plus versatiles afin de juger de sa performance de façon relative. / Markov Chain Monte Carlo algorithms (MCMC) have become popular tools for sampling from complex and/or high dimensional probability distributions. Given their relative ease of implementation, these methods are frequently used in various scientific areas, particularly in Statistics and Bayesian analysis. The volume of such methods has risen considerably since the first MCMC algorithm described in 1953 and this area of research remains extremely active. A new MCMC algorithm using a directional adjustment has recently been described by Bédard et al. (IJSS, 9:2008) and some of its properties remain unknown. The objective of this thesis is to attempt determining the impact of a key parameter on the global performance of the algorithm. Moreover, another aim is to compare this new method to existing MCMC algorithms in order to evaluate its performance in a relative fashion.
269

Étude du maximum et des hauts points de la marche aléatoire branchante inhomogène et du champ libre gaussien inhomogène

Ouimet, Frédéric 09 1900 (has links)
Voir la bibliographie du mémoire pour les références du résumé. See the thesis`s bibliography for the references in the summary. / Ce mémoire étudie le comportement du maximum et des hauts points de la marche aléatoire branchante et du champ libre gaussien discret en dimension deux lorsque la variance de leurs accroissements est inhomogène dans le temps. Nous regardons le cas où il y a un nombre fini d'échelles $0 = \lambda_0 < \lambda_1 < ... < \lambda_M = 1$ et des paramètres de variance $\sigma_i > 0$ associés aux intervalles de temps $[\lambda_{i-1},\lambda_i]$. La marche aléatoire branchante inhomogène généralise le modèle considéré dans [23] et le champ libre gaussien inhomogène généralise le modèle introduit dans [4]. Le but du mémoire est d'étendre les résultats connus sur la convergence du maximum [5,6,23] et le nombre de hauts points [16] à ces deux nouveaux champs gaussiens. Les résultats aident à mieux comprendre comment la perturbation des corrélations dans l'un ou l'autre des modèles de base influence l'ordre de grandeur du maximum et l'ordre du nombre de hauts points. / This thesis studies the behavior of the maximum and high points of the branching random walk and the Gaussian free field when the variance of their increments is time-inhomogeneous. We look at the case where there are a finite number of scales $0 = \lambda_0 < \lambda_1 < ... < \lambda_M = 1$ and variance parameters $\sigma_i > 0$ associated with the time intervals $[\lambda_{i-1},\lambda_i]$. The inhomogeneous branching random walk generalizes the model considered in [23] and the inhomogeneous Gaussian free field generalizes the model introduced in [4]. The purpose of the thesis is to extend known results on the convergence of the maximum [5,6,23] and the number of high points [16] to these new Gaussian fields. The results help to better understand how perturbations of the correlations in one or the other basic models influence the order of magnitude of the maximum and the order of the number of high points.
270

Théorème Central Limite pour les marches aléatoires biaisées sur les arbres de Galton-Watson avec feuilles

Rakotobe, Joss 09 1900 (has links)
L’objectif en arrière-plan est de montrer que plusieurs modèles de marches aléatoires en milieux aléatoires (MAMA) sont reliés à un modèle-jouet appelé le modèle de piège de Bouchaud. Le domaine des MAMA est très vaste, mais nous nous intéressons particulièrement à une classe de modèle où la marche est réversible et directionnellement transiente. En particulier, nous verrons pourquoi on pense que ces modèles se ressemblent et quel genre de similarités on s’attend à obtenir, une fois qu’on aura présenté le modèle de Bouchaud. Nous verrons aussi quelques techniques de base utilisés de ce domaine, telles que les temps de régénérations. Comme contribution, nous allons démontrer un théorème central limite pour la marche aléatoire β-biaisée sur un arbre de Galton-Watson. / This Master thesis is part of a larger project of linking the behaviours of a certain type of random walks in random environments (RWRE) with those of a toy model called the Bouchaud’s trap model. The domain of RWRE is very wide but our interest will be on a particular kind of models which are reversible and directionally transient. More specifically, we will see why those models have similar behaviours and what kind of results we could expect once we have reviewed the Bouchaud’s trap model. We will also present some basic technic used in this field, such as regeneration times. As a contribution, we will demonstrate a central limit theorem for the β-biased random walk on a Galton-Watson tree.

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