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Zeitreisen und Reisen mit Überlichtgeschwindigkeit sind zwei Menschheitsträume; sie beflügeln die Fantasie und bieten Stoff für skurrile Geschichten. Eine Arbeit zum Thema „Zeitreisen und Reisen mit Überlichtgeschwindigkeit“ zwingt zu einer Auseinandersetzung mit dem Begriff der „Zeit“. Die Vielschichtigkeit und der antinomische Charakter dieses Begriffes machen es schwer, „Zeit“ genauer zu fassen. Zeit tritt uns entgegen als Form der Wahrnehmung in ihrer zutiefst subjektiven Seite, als biologischer Rhythmus, als soziales Phänomen im Sinne einer kollektiven Zeitbestimmung, aber eben auch als physikalischer Parameter. Einsteins Relativitätstheorie revolutioniert unsere Vorstellungen von Raum und Zeit, indem sie sich vom newton-mechanischen Konzept des absoluten Raumes und der absoluten Zeit löst. Sie macht aber das, was bei Wells zehn Jahre vorher noch reine Fiktion war, zu einem für die Physik diskussionswürdigen Thema, nämlich das „Problem der Zeitreisen“. Einsteins Spezielle Relativitätstheorie (1905) erlaubt durch den von ihr vorhergesagten Effekt der Zeitdilatation „Reisen in die Zukunft“, und die Einstein’sche Gravitationstheorie lässt geschlossene zeitartige Linien als Lösungen ihrer Gleichungen zu (z. B. Gödel-Kosmos, Anti-de-Sitter-Kosmos). Allerdings würde eine Reise auf einer Zeitschleife sofort ein ganzes Bündel von Paradoxien (z. B. Großvater-Paradoxon, Informationsparadoxon) und semantischen Inkonsistenzen nach sich ziehen. Obwohl erstaunlicherweise die fundamentalen Gesetze der Physik (abgesehen von extrem seltenen und makroskopisch nicht in Erscheinung tretenden quantenmechanischen Effekten) bei einer Zeitumkehr nicht verletzt würden, scheint es in der Natur doch ein grundsätzliches Verbot von Vergangenheitsreisen zu geben. Der Physiker Dieter Zeh, dessen Position im Schlusskapitel der Arbeit näher beleuchtet wird, vertritt die Auffassung, dass die Science-Fiction-Literatur zum Thema „Zeitreisen“ überwiegend auf einfachen begrifflichen Fehlern beruhe. Die in Anlehnung an die Allgemeine Relativitätstheorie konstruierten Vorgänge seien bestenfalls genauso „theoretisch möglich“ wie ein Gas, das sich von selbst in einer Ecke des Gefäßes versammelt. Die vorliegende Arbeit erörtert Ansätze für „Zeitmaschinen“ und superluminale Prozesse, die in Einklang mit der modernen Physik stehen. Besprochen werden u. a. die Tachyonen-Hypothese, Tiplers rotierender Zylinder, der Gödel-Kosmos, der Anti-de-Sitter-Kosmos, die sogenannten „Wurmlöcher“ und die Alcubierre-Metrik. Zugleich sollen Ansätze vorgestellt werden (z. B. Eternalismus, Viele-Welten-Modell, Prinzip der konsistenten Geschichte), die Lösungsversuche für die Paradoxien von Vergangenheitsreisen bieten. Um die Reisen in die Vergangenheit und Reisen mit Überlichtgeschwindigkeit scheint es zu stehen wie mit einer Anfrage an Radio Jerewan; die Antwort lautet stets: „Im Prinzip ja, aber …“ Doch die Faszination dieser Idee wird weiterhin Stoff für die „Fiction“ liefern. / Time travel and superluminal travel are two of mankind's dreams. They inspire our imagination and provide material for bizarre stories. A work on the subject of time travel and superluminal travel forces us to re-examine our concept of "time". The complexity and the contradictory nature this subject makes it difficult to be more precise about "time". On its deepest subjective side, time is a means of perception, a biological rhythm, a social phenomenon in terms of our collective understanding of time. But it is also a physical parameter. Einstein's Theory of Relativity revolutionised our idea of space and time by freeing us from the Newtonian concept of absolute space and absolute time. The "problem of time travel", a subject that Wells wrote about just ten years before as mere fiction, was now a discussion worthy of physics. Einstein's Special Theory of Relativity (1905), by predicting the effects of time dilation, allowed for "travels into the future" and Einstein's Theory of Gravity used closed time-like lines for solutions to calculations about time travel (for example, the Gödel Universe and the Anti-de Sitter Universe). However, a trip to a time warp would immediately involve a whole set of paradoxes (for example, the grandfather paradox and the information paradox) and semantic inconsistencies. Surprisingly, the fundamental laws of physics (apart from extremely rare and non-emergent macroscopic quantum mechanical effects) are not violated by the concept of time reversal. Yet, in nature, there still seems to be a fundamental prohibition against time travel to the past. Physicist Dieter Zeh, whose position is more closely presented in the final chapter of this work, supports the view that science fiction literature on the subject of "time travel" is overwhelmingly based on simple conceptual errors. The processes used in this literature, which are based on the General Theory of Relativity, at best, are just as "theoretically possible" as a gas which gathers itself into the corner of a container. This work discusses approaches for "time machines" and superluminal travel which are consistent with modern physics. Some of the discussions that will be presented are the tachyon hypothesis, Tipler's rotating cylinder, the Gödel Universe, the Anti-de Sitter Universe, so-called "wormholes" and the Alcubierre-metric. At the same time, approaches will be presented (for example, Eternalism, the Many-Worlds Interpretation and the Consistent Histories Approach) that will provide attempts to find a solution for paradoxes regarding time travel to the past. Questions about time travel to the past and superluminal travel are like the questions asked on Radio Yerevan. The answer is always, "In principle yes, but…" But the fascination about time travel will continue to provide material for "fiction".

Zu Beginn des Forschungsvorhabens wurden im Rahmen der Teilprojekte B1 und B2 des SFB 532 alkalibeständige Glas- und Carbonrovings eingesetzt, die zu offenmaschigen 2D-Textilien verarbeitet wurden. Untersuchungen des Verbund- und des Tragverhaltens der Verstärkungsstrukturen in Pull-Out- und Dehnkörperversuchen haben gezeigt, dass das Potential der Verstärkungsfasern aufgrund einer unvollständiger Durchtränkung der Bewehrung nicht vollständig ausgeschöpft werden kann. Auch Defizite bei der Produktionstechnik wurden erkannt und für zukünftige Entwicklungen analysiert. Um das Potential der verwendeten Verstärkungsfaser vollständiger auszuschöpfen, wurden innovative Garnkonstruktionen, die sich positiv auf den inneren und/oder den äußeren Verbund auswirken, entwickelt und erprobt. Anhand von Versuchsreihen auf der Textilebene wurden unterschiedliche Textilparameter, wie Art der Bindung, Gittergröße und Wirkfadenspannung, identifiziert, die unmittelbar die Tragfähigkeit der Verbundbauteile beeinflussen. Für die gängigen Produktionstechniken Laminieren, Gießen, Spritzen, Schleudern und Extrudieren wurden entsprechende Bewehrungskonstruktionen abgeleitet, die den Anforderungen des jeweiligen Prozess angepasst wurden. Ein weiterer Punkt der Forschungsaktivitäten stellte die Entwicklung der Maschinentechnik zur Herstellung von Verstärkungstextilien dar. Am Institut für Textiltechnik (ITA) der RWTH Aachen University wurde in Zusammenarbeit mit Industriepartnern ein Maschinenkonzept entwickelt und umgesetzt, das die Herstellung von 3D-Abstandsgewirken mit einer freien Gestaltung der Deckflächen mit marktrelevanten Produktionsgeschwindigkeiten ermöglicht. Zur gezielten Einstellung der Wirkfadenspannung wurde ein Regelungssystem konzipiert und technisch umgesetzt, mit dem eine reproduzierbare Fertigung von textilen Verstärkungsstrukturen möglich wird.

Data collisions have been widely studied by various fields of science and industry. Combing CPU and GPU for processing spatial joins has been broadly accepted due to the increased speed of computations. This should redirect efforts in GPGPU research from straightforward porting of applications to establishing principles and strategies that allow efficient mapping of computation to graphics hardware. As threads are executing instructions while using hardware resources that are available, impact of different thread organizations and their effect on spatial join performance is analyzed and examined in this report.Having new perspectives and solutions to the problem of thread organization and warp scheduling may contribute more to encourage others to program on the GPU side. The aim with this project is to examine the impact of different thread organizations in spatial join processes. The relationship between the items inside datasets are examined by counting the number of collisions their join produce in order to understand how different approaches may have an influence on performance. Performance benchmarking, analysis and measuring of different approaches in thread organization are investigated and analyzed in this report in order to find the most time efficient solution which is the purpose of the conducted work.This report shows the obtained results for the utilization of different thread techniques in order to optimize the computational speeds of the spatial join algorithms. There are two algorithms on the GPU, one implementing thread techniques and the other non-optimizing solution. The GPU times are compared with the execution times on the CPU and the GPU implementations are verified by observing the collision counters that are matching with all of the collision counters from the CPU counterpart.In the analysis part of this report the the implementations are discussed and compared to each other. It has shown that the difference between algorithm implementing thread techniques and the non-optimizing one lies around 80% in favour of the algorithm implementing thread techniques and it is also around 56 times faster then the spatial joins on the CPU. / Datakollisioner har studerats i stor utsträckning i olika områden inom vetenskap och industri. Att kombinera CPU och GPU för bearbetning av rumsliga föreningar har godtagits på grund av bättre prestanda. Detta bör omdirigera insatser i GPGPU-forskning från en enkel portning av applikationer till fastställande av principer och strategier som möjliggör en effektiv användning av grafikhårdvara. Eftersom trådar som exekverar instruktioner använder sig av hårdvaruresurser, förekommer olika effekter beroende på olika trådorganisationer. Deras på verkan på prestanda av rumsliga föreningar kommer att analyseras och granskas i denna rapport. Nya perspektiv och lösningar på problemet med trådorganisationen och schemaläggning av warps kan bidra till att fler uppmuntras till att använda GPU-programmering. Syftet med denna rapport är att undersöka effekterna av olika trådorganisationer i rumsliga föreningar. Förhållandet mellan objekten inom datamängder undersöks genom att beräkna antalet kollisioner som ihopslagna datamängder förorsakar. Detta görs för att förstå hur olika metoder kan påverka effektivitet och prestanda. Prestandamätningar av olika metoder inom trå dorganisationer undersö ks och analyseras fö r att hitta den mest tidseffektiva lösningen. I denna rapport visualiseras också det erhållna resultatet av olika trådtekniker som används för att optimera beräkningshastigheterna för rumsliga föreningar. Rapporten undersökeren CPU-algoritm och två GPU-algoritmer. GPU tiderna jämförs hela tiden med exekveringstiderna på CPU:n, och GPU-implementeringarna verifieras genom att jämföra antalet kollisioner från både CPU:n och GPU:n. Under analysdelen av rapporten jämförs och diskuteras olika implementationer med varandra. Det visade sig att skillnaden mellan en algoritm som implementerar trådtekniker och en icke-optimerad version är cirka 80 % till förmån för algoritmen som implementerar trådtekniker. Det visade sig också föreningarna på CPU:n att den är runt 56 gånger snabbare än de rumsliga

Cette thèse a été réalisée au sein des laboratoires du GEMTEX et du LAMIH, et porte sur l’étude et l’évaluation d’une solution composite à renfort tissé pour la protection balistique de véhicule. L’enjeu de cette thèse consiste à explorer le potentiel des solutions en composite à renfort tissé interlock 3D dans le cas d’unimpact à haute vitesse. Deux solutions composites ont été mis au point en laboratoire, intégrant le même renfort tissé interlock mais mis en oeuvre par deux procédés d'imprégnation différents. Ces composites ont été évalués à l’impact par un FSP (Fragment Simulating Projectile) de 20 mm de diamètre, dans une configuration de backing, c'est-à-dire en face arrière d’une plaque métallique utilisée pour la protection contre les impacts à haute vitesse.Plusieurs campagnes d’essais ont été réalisées permettant d’optimiser nos structures interlocks 3D afin de répondre au mieux à la sollicitation dynamique. Les résultats à l’impact de ces composites ont été comparés à ceux d’une solution composite dite de référence généralement utilisée dans les véhicules blindés à base de tissés 2D empilés suivant différentes directions. Ces essais nous ont permis de faire ressortir les performances de l’une des structures développée présentant des capacités de protection à l’impact supérieures aux composites de référence.Afin d’en comprendre les mécanismes des renforts mis en jeu, nous avons représenté numériquement ces tissus interlocks soumis à l’impact. Des modèles numériques innovants ont été simulés dans le but de représenter le renfort tissé de façon réaliste grâce aux mesures obtenues par micro-tomographie à rayons X. / This thesis was performed at the laboratories of GEMTEX and LAMIH on study and evaluation of a solution based on warp interlock reinforced composite for vehicle ballistic protection. The main purpose of this thesis is to explore the potential of warp interlock reinforced composite solutions in the case of a high velocity impact. We have chosen to study two composite solutions manufactured in our laboratory which presented the same warp interlock reinforcement but with different resins and infusion processes. Those composites were tested by an FSP (Fragment Simulating Projectile) impact as armour backing. Few campaign of tests were performed which helped us to optimize our warp interlock structure in order tohave a better response to the dynamic loading. The impact results of our composites have been compared with those of the benchmark which is a composite generally used backing. Thanks to these tests we had the possibility to observe that one of our structures present a better impact behaviour than the others. In order to improve our representation of those reinforcement, we have been working on the numerical modelling of those warp interlock submitted to impact. Innovative numerical models have been set up thanks to micro-tomography analysis allowing a more realistic representation of the reinforcement.

Designing generalized data-driven distance measures for both ordered and unordered set data is the core focus of the proposed work. An ordered set is a set where time-linear property is maintained when distance between pair of temporal segments. One application in the ordered set is the human gesture analysis from RGBD data. Human gestures are fast becoming the natural form of human computer interaction. This serves as a motivation to modeling, analyzing, and recognition of gestures. The large number of gesture categories such as sign language, traffic signals, everyday actions and also subtle cultural variations in gesture classes makes gesture recognition a challenging problem. As part of generalization, an algorithm is proposed as part of an overlap speech detection application for unordered set. Any gesture recognition task involves comparing an incoming or a query gesture against a training set of gestures. Having one or few samples deters any class statistic learning approaches to classification, as the full range of variation is not covered. Due to the large variability in gesture classes, temporally segmenting individual gestures also becomes hard. A matching algorithm in such scenarios needs to be able to handle single sample classes and have the ability to label multiple gestures without temporal segmentation. Each gesture sequence is considered as a class and each class is a data point on an input space. A pair-wise distances pattern between to gesture frame sequences conditioned on a third (anchor) sequence is considered and is referred to as warp vectors. Such a process is defined as conditional distances. At the algorithmic core we have two dynamic time warping processes, one to compute the warp vectors with the anchor sequences and the other to compare these warp vectors. We show that having class dependent distance function can disambiguate classification process where the samples of classes are close to each other. Given a situation where the model base is large (number of classes is also large); the disadvantage of such a distance would be the computational cost. A distributed version combined with sub-sampling anchor gestures is proposed as speedup strategy. In order to label multiple connected gestures in query we use a simultaneous segmentation and recognition matching algorithm called level building algorithm. We use the dynamic programming implementation of the level building algorithm. The core of this algorithm depends on a distance function that compares two gesture sequences. We propose that, we replace this distance function, with the proposed distances. Hence, this version of level building is called as conditional level building (clb). We present results on a large dataset of 8000 RGBD sequences spanning over 200 gesture classes, extracted from the ChaLearn Gesture Challenge dataset. The result is that there is significant improvement over the underlying distance used to compute conditional distance when compared to conditional distance. As an application of unordered set and non-visual data, overlap speech segment detection algorithm is proposed. Speech recognition systems have a vast variety of application, but fail when there is overlap speech involved. This is especially true in a meeting-room setting. The ability to recognize speaker and localize him/her in the room is an important step towards a higher-level representation of the meeting dynamics. Similar to gesture recognition, a new distance function is defined and it serves as the core of the algorithm to distinguish between individual speech and overlap speech temporal segments. The overlap speech detection problem is framed as outlier detection problem. An incoming audio is broken into temporal segments based on Bayesian Information Criterion (BIC). Each of these segments is considered as node and conditional distance between the nodes are determined. The underlying distances for triples used in conditional distances is the symmetric KL distance. As each node is modeled as a Gaussian, the distance between the two segments or nodes is given by Monte-Carlo estimation of the KL distance. An MDS based global embedding is created based on the pairwise distance between the nodes and RANSAC is applied to compute the outliers. NIST meeting room data set is used to perform experiments on the overlap speech detection. An improvement of more than 20% is achieved with conditional distance based approach when compared to a KL distance based approach.

In recent years, a number of power control concepts have been studied and implementedeither in simulation or in practice for different communication systems. It is still the case that a great deal of research is being conducted within the area of energyefficient power control mechanisms for future wireless communication networksystems. However, only a limited amount of practical work has been implemented onreal test beds environment. The main goal of this thesis is to propose and develop newprototype Transmit Power Control Mechanisms (TPCM) on WARP (Wireless Open-Access Research Platform) boards for point-to-point communications, which are to bedeveloped and tested in an indoor environment. This work mainly focuses on the automaticpower control nodes, transmission and reception over-the-air. In this thesis, wehave designed and developed TPCM to adjust the power levels on a transmitter nodeby following the feedback (ACK) approach. In this case, the destination (receiver)node always sends the feedback (ACK) to transmitter node during every successfultransmission of message signal and the main focus is on a reduction in the packetloss rate (PLR), an increase in the packet reception rate (PRR) and the capacity ofthe nodes. In this real work, we have developed and measured the results based ontwo functions namely, with and without packet window function power control mechanisms. According to the measurements section, both with and without function powercontrol mechanisms proved to have better performances for different tunable parameters.If both functions are compared, then the with window function power controlmechanism was shown to produce better performances than the without windowpower control mechanism and it also converged faster than the without window function.If consideration was given to controlling a reduction in packet loss rate, thenthe with widnow function offered higher performances than those without the windowfunction. In this regard, it was found that the with window function has acheived amaximum packet reception rate than that for the without window function for differenttunable parameters. In relation to the power consumption scenario, it was determinedthat the without window fuction proved to produce energy saving performances thanthe with window function. There are several interesting aspects of the transmit powercontrol mechanisms highlighted in the results and discussion chapter.

MU-MIMO theory predicts manyfold capacity gains by leveraging many antennas (e.g. M >> 10) on wireless base stations to serve many users simultaneously through multi-user beamforming (MUBF). However, realizing such a large-scale design is nontrivial, and has yet to be achieved in the real world. We present the design, realization, and evaluation of Argos, the first reported large-scale base station that is capable of serving many (e.g., 10s of) terminals simultaneously through MUBF. Designed with extreme flexibility and scalability in mind, Argos exploits hierarchical and modular design principles, properly partitions baseband processing, and holistically considers real-time requirements of MUBF. To achieve unprecedented scalability, we devise a novel, completely distributed, beamforming technique, as well as an internal calibration procedure to enable implicit beamforming across large arrays. We implement a prototype with 64 antennas, and demonstrate that it can achieve up to 6.7 fold capacity gains while using a mere 1/64th the transmission power.