Cette thèse regroupe nos résultats sur la prédiction de séries temporelles dépendantes. Le document comporte trois chapitres principaux où nous abordons des problèmes différents. Le premier concerne l’agrégation de prédicteurs de décalages de Bernoulli Causales, en adoptant une approche Bayésienne. Le deuxième traite de l’agrégation de prédicteurs de ce que nous définissions comme processus sous-linéaires. Une attention particulaire est portée aux processus autorégressifs localement stationnaires variables dans le temps, nous examinons un schéma de prédiction adaptative pour eux. Dans le dernier chapitre nous étudions le modèle de régression linéaire pour une classe générale de processus localement stationnaires. / This thesis regroups our results on dependent time series prediction. The work is divided into three main chapters where we tackle different problems. The first one is the aggregation of predictors of Causal Bernoulli Shifts using a Bayesian approach. The second one is the aggregation of predictors of what we define as sub-linear processes. Locally stationary time varying autoregressive processes receive a particular attention; we investigate an adaptive prediction scheme for them. In the last main chapter we study the linear regression problem for a general class of locally stationary processes.

The study experimentally examines the quasi-static shear deformation of a magnetorheological (MR) fluid structured in an external magnetic field. Experiments are carried out using a rheometer with a plate–plate configuration. The working surfaces of the measuring geometry are modified to demonstrate their influence on the response of the field-structured MR fluid. The simplest possible suspension of microparticles of carbonyl iron in mineral oil without using surfactants or any modifiers is used. The difference in results obtained for structured MR fluid with different concentrations of magnetic particles using different modifications of the surface is demonstrated. The results are intended to motivate more intensive research on the issue and further more in-depth theoretical analysis of static elastic properties of structured MR fluids. Certain related critical issues are briefly highlighted.

It is no secret that the world is facing major climate challenges. One of the aspects that can contribute to a greener future is to reconsider our means of transport. That bicycles is part of the solution and also contributes to the public health is something that is gaining more and more traction in society. An aspect though, that has received far too little attention and is the basis of this work is broken-down, stationary bicycles. Something that neither benefits the individual nor society at large. What this work aims to explore is why this happens, how it can be avoided and how to get bike owners to actually repair their bikes. This through a user-centered design process that is based on the users' situation and needs. This project is a bachelor’s thesis within industrial design engineering that has been carried out during spring 2022 at Luleå University of Technology. Through a user-centered process based on several methods such as guerilla interviews, participatory observation, and context research, a broad picture of the current situation was created. Based on this, creative methods such as brainstorming and workshops were then used to create a large number of ideas based on the users' needs. A thorough idea evaluation, mockups and a dot-voting then sifted these ideas down to a final concept where wireframes and prototyping ensured that the concept could be realized. The result of the project was the following; users don’t repair their bikes because they are insecure, lack knowledge and do not trust their abilities. They consider repairing to be a project that feels tedious and difficult to begin with. The users need a simple, clear solution that creates security and presents relevant information. The solution landed in the concept  A rolling bicycle consisting of two parts and a total of three steps. The first part is a number of posters to create incentives to repair one's bike and the second part an application that contains both a guide before the repair, but also instructions during the repair itself. The flow is a result of the needs and function analysis that was carried out and whose components are intended to meet the needs and conditions of users to get more people to fix their bike. / Att världen står inför stora klimatutmaningar är ingen hemlighet. En av de aspekter som kan bidra till en grönare framtid är att se över vårt val av transportmedel. Att cykeln är en del av lösningen och som även bidrar till folkhälsan är något som får allt större plats i samhället. En aspekt som fått allt för lite uppmärksamhet och som är grunden till detta arbete är trasiga, stillastående cyklar. Något som varken gynnar individen eller samhället i stort. Det här arbetet utforskar varför detta sker, hur det kan undvikas och hur man kan få cykelägare att faktiskt reparera sin cykel. Detta genom en användarcentrerad designprocess som utgått från användarnas situation och behov. Projektet är ett examensarbete på kanditatnivå inom utbildningen teknisk design. Projektet har utförts under läsperiod 4, vårterminen 2022 på Luleå tekniska universitet. Genom en användarcentrerad process grundad i flertalet metoder såsom gerillaintervjuer, deltagande observationer, och kontextundersökning skapades en bred bild av nuläget. Baserat på detta gjordes sedan kreativa metoder såsom brainstorming och workshops för att skapa ett stort antal idéer utifrån användarnas behov. En grundlig idéavaluering, mockups samt en dot-voting sållade sedan ner dessa idéer till ett slutkoncept där wireframes och prototypande såg till att konceptet kunde förverkligas. Resultatet av arbetet blev följande; användarna reparerar inte sina cyklar för att de är osäkra, saknar kunskap och inte litar på sin egen förmåga. De anser lagning vara ett projekt som känns jobbigt och svårt att påbörja. Användarna har ett behov av en enkel, tydlig lösning som skapar en trygghet och presenterar relevant information. Denna lösning landade i konceptet En rullande cykel som består av två delar och totalt tre steg. Den första delen är ett antal affischer för att skapa incitament till att laga sin cykel och den andra delen en applikation som innehåller både en guide inför reparation, men också instruktioner under själva reparationen. Detta flöde är ett resultat av den behovs och funktionsanalys som utfördes och vars komponenter har som avsikt att bemöta användarnas behov och förutsättningar för att få fler att laga sin cykel.

No description available.

No description available.

No description available.

<p>In this dissertation stochastic processes are regarded in the framework of Colombeau-type algebras of generalized functions. Such processes are called Colombeau stochastic processes.The notion of point values of Colombeau stochastic processes in compactly supported generalized points is established. The Colombeau algebra of compactly supported generalized constants is endowed with the topology generated by sharp open balls. The measurability of the corresponding random variables with values in the Colombeau algebra of compactly supported generalized constants is shown.<br />The generalized correlation function and the generalized characteristic function of Colombeau stochastic processes are introduced and their properties are investigated. It is shown that the characteristic function of classical stochastic processes can be embedded into the space of generalized characteristic functions. Examples of generalized characteristic function related to gaussian Colombeau stochastic<br />processes are given. The structural representation of the generalized correlation function which is supported on the diagonal is given. Colombeau stochastic processes with independent values are introduced. Strictly stationary and weakly stationary Colombeau stochastic processes are studied. Colombeau stochastic processes with stationary increments are characterized via their stationarity of the gradient of the process.Gaussian stationary solutions are analyzed for linear stochastic partial differential equations with generalized constant coefficients in the framework of Colombeau stochastic processes.</p> / <p>U disertaciji se stohastički procesi posmatraju u okviru Kolomboove algebre uop&scaron;tenih funkcija. Takve procese nazivamo Kolomboovi stohastički procesi. Pojam vrednosti Kolomboovog stohastičkog procesa u tačkama sa kompaktnim nosačem je uveden. Dokazana je merljivost odgovarajuće slučajne promenljive sa vrednostima u Kolomboovoj algebri uop&scaron;tenih konstanti sa kompaktnim nosačem,&nbsp; snabdevenom topologijom generisanom o&scaron;trim otvorenim loptama. Uop&scaron;tena korelacijska funkcija i uop&scaron;tena karakteristična funkcija Kolomboovog stohastičkog procesa su definisane i njihove osobine su izučavane. Pokazano je da&nbsp; se karakteristična funkcija klasičnog stohastičkog procesa može potopiti u prostor uop&scaron;tenih karakterističnih funkcija. Dati su primeri uop&scaron;tenih karakterističnih funkcija&nbsp; gausovskih Kolomboovih stohastičkih procesa. Data je strukturna reprezentacija uop&scaron;tene korelacijske funkcije sa nosačem na dijagonali. Kolomboovi stohastički procesi sa nezavisnim vrednostima su predstavljeni. Izučavani su strogo stacionarni i&nbsp; slabo stacionarni Kolomboovi stohastički procesi. Kolomboovi stohastički procesi sa stacionarnim prira&scaron;tajima su okarakterisani preko stacionarnosti gradijenta procesa. Gausovska stacionarna re&scaron;enja za linearnu stohastičku parcijalnu diferencijalnu jednačinu sa uop&scaron;tenim konstantnim koeficijentima su analizirana u okvirima Kolomboovih stohastičkih procesa.</p>

The inability to effectively hedge against unfavourable exchange rate movements, using the current forward exchange rate as the only guideline, is a key inhibiting factor of international trade. Market participants use the current forward exchange rate quoted in the market to make decisions regarding future exchange rate changes. However, the current forward exchange rate is not solely determined by the interaction of demand and supply, but is also a mechanistic estimation, which is based on the current spot exchange rate and the carry cost of the transaction. Results of various studies, including this study, demonstrated that the current forward exchange rate differs substantially from the realized future spot exchange rate. This phenomenon is known as the exchange rate puzzle. This study contributes to the dynamics of modelling exchange rate theories by developing an exchange rate model that has the ability to explain the realized future spot exchange rate and the exchange rate puzzle. The exchange rate model is based only on current (time t) economic fundamentals and includes an alternative approach of incorporating the impact of the interaction of two international financial markets into the model. This study derived a unique exchange rate model, which proves that the exchange rate puzzle is a pseudo problem. The pseudo problem is based on the generally excepted fallacy that current non–stationary, level time series data cannot be used to model exchange rate theories, because of the incorrect assumption that all the available econometric methods yield statistically insignificant results due to spurious regressions. Empirical evidence conclusively shows that using non–stationary, level time series data of current economic fundamentals can statistically significantly explain the realized future spot exchange rate and, therefore, that the exchange rate puzzle can be solved. This model will give market participants in the foreign exchange market a better indication of expected future exchange rates, which will considerably reduce the dependence on the mechanistically derived forward points. The newly derived exchange rate model will also have an influence on the demand and supply of forward exchange, resulting in forward points that are a more accurate prediction of the realized future exchange rate. / Thesis (Ph.D. (Risk management))--North-West University, Potchefstroom Campus, 2011.

The inability to effectively hedge against unfavourable exchange rate movements, using the current forward exchange rate as the only guideline, is a key inhibiting factor of international trade. Market participants use the current forward exchange rate quoted in the market to make decisions regarding future exchange rate changes. However, the current forward exchange rate is not solely determined by the interaction of demand and supply, but is also a mechanistic estimation, which is based on the current spot exchange rate and the carry cost of the transaction. Results of various studies, including this study, demonstrated that the current forward exchange rate differs substantially from the realized future spot exchange rate. This phenomenon is known as the exchange rate puzzle. This study contributes to the dynamics of modelling exchange rate theories by developing an exchange rate model that has the ability to explain the realized future spot exchange rate and the exchange rate puzzle. The exchange rate model is based only on current (time t) economic fundamentals and includes an alternative approach of incorporating the impact of the interaction of two international financial markets into the model. This study derived a unique exchange rate model, which proves that the exchange rate puzzle is a pseudo problem. The pseudo problem is based on the generally excepted fallacy that current non–stationary, level time series data cannot be used to model exchange rate theories, because of the incorrect assumption that all the available econometric methods yield statistically insignificant results due to spurious regressions. Empirical evidence conclusively shows that using non–stationary, level time series data of current economic fundamentals can statistically significantly explain the realized future spot exchange rate and, therefore, that the exchange rate puzzle can be solved. This model will give market participants in the foreign exchange market a better indication of expected future exchange rates, which will considerably reduce the dependence on the mechanistically derived forward points. The newly derived exchange rate model will also have an influence on the demand and supply of forward exchange, resulting in forward points that are a more accurate prediction of the realized future exchange rate. / Thesis (Ph.D. (Risk management))--North-West University, Potchefstroom Campus, 2011.

Cette recherche a pour but d’évaluer le rôle de la vision et de la proprioception pour la perception et le contrôle de l’orientation spatiale de la main chez l’humain. L’orientation spatiale de la main est une composante importante des mouvements d’atteinte et de saisie. Toutefois, peu d’attention a été portée à l’étude de l’orientation spatiale de la main dans la littérature. À notre connaissance, cette étude est la première à évaluer spécifiquement l’influence des informations sensorielles et de l’expérience visuelle pour la perception et le contrôle en temps réel de l'orientation spatiale de la main pendant le mouvement d’atteinte naturel vers une cible stationnaire. Le premier objectif était d’étudier la contribution de la vision et de la proprioception dans des tâches de perception et de mouvement d’orientation de la main. Dans la tâche de perception (orientation-matching task), les sujets devaient passivement ou activement aligner une poignée de forme rectangulaire avec une cible fixée dans différentes orientations. Les rotations de l’avant-bras et du poignet étaient soit imposées par l’expérimentateur, soit effectuées par les sujets. Dans la tâche de mouvement d’orientation et d’atteinte simultanées (letter posting task 1), les sujets ont réalisé des mouvements d’atteinte et de rotation simultanées de la main afin d’insérer la poignée rectangulaire dans une fente fixée dans les mêmes orientations. Les tâches ont été réalisées dans différentes conditions sensorielles où l’information visuelle de la cible et de la main était manipulée. Dans la tâche perceptive, une augmentation des erreurs d’orientation de la main a été observée avec le retrait des informations visuelles concernant la cible et/ou ou la main. Lorsque la vision de la main n’était pas permise, il a généralement été observé que les erreurs d’orientation de la main augmentaient avec le degré de rotation nécessaire pour aligner la main et la cible. Dans la tâche de mouvement d’orientation et d’atteinte simultanées, les erreurs ont également augmenté avec le retrait des informations visuelles. Toutefois, les patrons d’erreurs étaient différents de ceux observés dans la tâche de perception, et les erreurs d’orientation n’ont pas augmenté avec le degré de rotation nécessaire pour insérer la poignée dans la fente. En absence de vision de la main, il a été observé que les erreurs d’orientation étaient plus petites dans la tâche de mouvement que de perception, suggérant l’implication de la proprioception pour le contrôle de l’orientation spatiale de la main lors des mouvements d’orientation et d’atteinte simultanées. Le deuxième objectif de cette recherche était d’étudier l’influence de la vision et de la proprioception dans le contrôle en temps réel de l’orientation spatiale de la main. Dans une tâche d’orientation de la main suivie d’une atteinte manuelle (letter posting task 2), les sujets devaient d’abord aligner l’orientation de la même poignée avec la fente fixée dans les mêmes orientations, puis réaliser un mouvement d’atteinte sans modifier l’orientation initiale de la main. Une augmentation des erreurs initiales et finales a été observée avec le retrait des informations visuelles. Malgré la consigne de ne pas changer l’orientation initiale de la main, une diminution des erreurs d’orientation a généralement été observée suite au mouvement d’atteinte, dans toutes les conditions sensorielles testées. Cette tendance n’a pas été observée lorsqu’aucune cible explicite n’était présentée et que les sujets devaient conserver l’orientation de départ de la main pendant le mouvement d’atteinte (mouvement intransitif; letter-posting task 3). La diminution des erreurs pendant l’atteinte manuelle transitive vers une cible explicite (letter-posting task 2), malgré la consigne de ne pas changer l’orientation de la main pendant le mouvement, suggère un mécanisme de corrections automatiques pour le contrôle en temps réel de l’orientation spatiale de la main pendant le mouvement d’atteinte naturel vers une cible stationnaire. Le troisième objectif de cette recherche était d’évaluer la contribution de l’expérience visuelle pour la perception et le contrôle de l’orientation spatiale de la main. Des sujets aveugles ont été testés dans les mêmes tâches de perception et de mouvement. De manière générale, les sujets aveugles ont présenté les mêmes tendances que les sujets voyants testés dans la condition proprioceptive (sans vision), suggérant que l’expérience visuelle n’est pas nécessaire pour le développement d’un mécanisme de correction en temps réel de l’orientation spatiale de la main basé sur la proprioception. / The goal of this research was to study the contribution of vision and proprioception to the perception and control of hand orientation in human subjects. Spatial orientation of the hand is an important component of reaching and grasping movements. However, not much attention has been given to spatial hand orientation in the literature. To our knowledge, this study is the first to specifically investigate the influence of sensory information for the perception and on-line control of hand orientation during natural reaching movement to stationary targets. The first objective of this research was to study the contribution of vision and proprioception in perceptual orientation-matching and motor letter posting tasks. In the perceptual orientation-matching task, subjects attempted to passively or actively align a match handle, to a target that was fixed in different orientations. In the passive perceptual task, passive rotations of the forearm and wrist were imposed by the experimenter; whereas in the active perceptual task, the rotations were actively executed by the subjects. In letter posting task 1, subjects simultaneously reached and rotated the right hand to insert a match handle into a target slot fixed in the same orientations. The tasks were performed in different sensory conditions where the visual information about the target and the hand was manipulated. In the perceptual orientation-matching task, augmentation of hand orientation errors was observed with the withdrawal of visual information related to either the target and/or the hand. When full vision was not allowed, hand orientation errors were larger overall when larger rotations of the wrist were required to match the target, whether the rotations were made actively by the subject or were imposed passively by the experimenter. In letter posting task 1, augmentation of hand orientation errors was also observed with the withdrawal of visual information related to either the target and/or the hand. However, errors patterns were different from those observed in the perceptual task, and hand orientation errors were not larger for larger target orientations. Without vision of the hand, final hand orientation errors were smaller overall in letter-posting task 1 than in the orientation-matching task. This suggests the implication of the proprioceptive information for the control of spatial hand orientation during reach-and-orient movements. The second objective of this research was to study the influence of vision and proprioception in on-line control of spatial hand orientation. In letter posting task 2, subjects first aligned their hand to the angle of the target and then reached to it with the instruction not to change their initial hand orientation. The augmentation of initial and final errors was observed with the withdrawal of vision. Although subjects were instructed to not change their hand orientation, in all sensory condition tested, hand orientation changed overall during reaching in a way that reduced the initial orientation errors. This trend did not occur when there was no explicitly defined target toward which the subjects reached (letter-posting task 3; intransitive movement). The reduction in hand orientation errors during transitive reach in letter-posting task 2, even when told not to change it, suggests the engagement of an automatic error correction mechanism for hand orientation during natural reaching movements toward stationary targets. The third objective of this research was to investigate the contribution of visual experience to the perception and control of spatial orientation of the hand. Blind subjects were tested in the same perceptual and motor tasks. Overall, no differences were observed between performance of blind subjects and normally-sighted subjects tested without vision (proprioceptive condition), suggesting that prior visual experience is not necessary for the development of an on-line error correction mechanism for hand orientation guided by proprioceptive inputs.