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Vor dem Starten ankommen : Über Zeitreisen und Warp-Antriebe
Get PDFZeitreisen 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"
Lane Detection based on Contrast Analysis
Get PDFComputer vision and image processing systems are ubiquitous in automotive domain and manufacturing industry. Lane detection warning systems has been an elementary part of the modern automotive industry. Due to the recent progress in the computer vision and image processing methods, economical and flexible use of computer vision is now pervasive and computing with images is not just for the realm of the science, but also for the arts and social science and even for hobbyists. Image processing is a key technology in automotive industry, even now there is hardly a single manufacturing process that is thinkable without imaging. The applications of image processing and computer vision methods in embedded systems platform, is an ongoing research area since many years. OpenCV, an open-source computer vision library containing optimized algorithms and methods for designing and implementing applications based on video and image processing techniques. These method are organized in the form of modules for specific field including, user-graphic interface, machine learning, feature extraction etc [43]. Vision-based automotive application systems become an important mechanism for lane detection and warning systems to alert a driver about the road in localization of the vehicle [1]. In automotive electronic market, for lane detection problem, vision-based approaches has been designed and developed using different electronic hardware and software components including wireless sensor, camera module, Field-Programmable Gate Array (FPGA) based systems, GPU and digital signal processors (DSP) [13]. The software module consists on the top of real-time operating systems and hardware description programming language including Verilog, or VHDL. One of the most time critical task of vision based systems is to test system applications in real physical environment with wide variety of driving scenarios and validating the whole systems as per the automotive industry standards. For validating and testing the advanced driver assistance systems, there are some commercial tools available including Assist ADTF from Elektrobit, EB company [43]. In addition to the design and strict real-time requirements for advanced driver assistance systems applications based on electronic components and embedded platform, the complexity and characteristics of the implemented algorithms are two parameters that need to be taken into consideration choosing hardware and software component [13]. The development of vision-based automotive application, based on alone electronic and micro-controller is not a feasible solution approach [35] [13] and GPU based solution are attractive but has many other issues including power consumption. In this thesis project, image and video processing module is used from OpenCV library for road lane detection problems. In proposed lane detection methods, low-level image processing algorithms and methods are used to extract relevant information for lane detection problem by applying contrast analysis at pixel level intensity values. Furthermore, the work at hand presents different approaches for solving relevant partial problems in the domain of lane detection. The aim of the work is to apply contrast analysis based on low-level image processing methods to extract relevant lane model information from the grid of intensity values of pixel elements available in image frame. The approaches presented in this project work are based on contrast analysis of binary mask image frame extracted after applying range threshold. A set of points, available in an image frame, based lane feature models are used for detecting lanes on color image frame captured from video. For the performance measurement and evaluation, the proposed methods are tested on different systems setup, including Linux, Microsoft Windows, CodeBlocks, Visual Studio 2012 and Linux based Rasbian-Jessie operating systems running on Intel i3, AMD A8 APU, and embedded systems based (Raspberry Pi 2 Model B) ARM v7 processor respectively
Einfluss des Materialzustandes einer EN-AW 6.xxx-Legierung auf das Umformverhalten und die FE-Berechnung
Get PDFEine effiziente und effektive Technologieentwicklung und –optimierungen im Bereich der Umform- und Fertigungstechnik erfolgt heutzutage fast ausschließlich rechnergestützt auf Basis der Finiten Elemente Methode (FEM) oder der Finiten Differenzen Methode (FDM). Die aktuellen Umformsimulationssysteme sind in der Lage die notwendige Energie der Anlagen, den prozessbedingten Stofffluss des Umformgutes inkl. der resultierenden Temperaturen und die Spannungen des Halbzeuges bzw. Bauteiles als auch der Werkzeuge vorauszuberechnen. Allerdingssind bereits dafür die sehr sensitiven Materialdaten, wie z. B. temperatur- und umformgeschwindigkeitsabhängige Fließkurven, Wärmeleitfähigkeit usw., notwendig. Momentane Forschungsaktivitäten beschäftigen sich damit, den nächsten Schritt der FE-Simulation zu bewältigen, in dem die Gefügeentwicklung und die daraus resultierenden mechanischen Eigenschaften (Zugfestigkeit, Bruchdehnung etc.) numerisch ermittelt werden können. Auch dafür müssen sehr aufwendige und materialspezifische Materialdaten generiert und modelliert und abschließend in Simulationssysteme über Schnittstellen implementiert werden. Die Vorhersage zu Verschleiß und Versagen von Werkzeugen wird in Zukunft immer mehr in das Interesse von Anwendern von FE-Software rücken, um die kompletten Einflussgrößen der Prozesse abzubilden. Dieser Beitrag soll am Beispiel einer aushärtbaren Aluminiumlegierung (EN AW 6.xxx) verdeutlichen, wie unterschiedlich das Materialverhalten in Abhängigkeit des Ausgangszustandes (stranggepresst, stranggegossen) und der Erwärmungsmodi (konvektiv, induktiv) sein kann und wie sich diese Variationen für ein und denselben Werkstoff auf die Berechnungsgenauigkeit ausgewählter Warmmassivumformprozesse (Reckwalzen, Gesenkschmieden) auswirkt
Lastverteilungsberechnung an doppelschrägverzahnten Planetengetrieben
Get PDFDie ersten Umlaufrädergetriebe wurden in Planetarien verwendet, um die Bewegung der Gestirne exakt aufzuzeigen. Bis in die zweite Hälfte des 19. Jahrhunderts wurden sie danach meist zur Lösung schwieriger Regelaufgaben verwendet. Erst durch größere Fortschritte in der Werkstoff- und Fertigungstechnik wurden Umlaufrädergetriebe als Drehmomentenwandler eingesetzt. Dadurch konnten die großen Vorteile der Umlaufrädergetriebe gegenüber Stirnradgetrieben in der Antriebstechnik genutzt werden. Umlaufrädergetriebe ermöglichen hohe Übersetzungen bei geringem Bauraum und Gewicht, da die Leistung über mehrere Zahnkontakte übertragen wird. Des Weiteren gibt es neben dem Zweiwellenbetrieb die Möglichkeit, im Dreiwellenbetrieb voneinander unabhängige Drehbewegungen zu überlagern. Dadurch sind beispielsweise Regelungsaufgaben bei Windenergieanlagen möglich. Dabei wird die Ungleichförmigkeit des Windes über einen zweiten drehzahlvariablen Antrieb ausgeglichen, damit am Abtrieb eine stets gleichmäßige Drehzahl am Generator anliegt. Weitere Vorteile sind die koaxiale Lage von Antrieb und Abtrieb und die symmetrische Bauform. MDESIGN LVR planet wurde entwickelt, um die Berechnung der Lastverteilung über der Zahnflanke und der Lastaufteilung auf die Planetenräder in Planetengetrieben zu übernehmen. Es ist möglich, diese Berechnung für geradverzahnte, einfachschräg- und doppeltschrägverzahnte Planetengetriebe im Zwei- und Dreiwellenbetrieb durchzuführen. Da doppelschrägverzahnte Planetengetriebe in Getrieben mit hohen Drehzahlen häufig in der Industrie verwendet werden, untersucht diese Forschungsarbeit die Theorie zur Umsetzung der Berechnung von Lastverteilungen unter dem Aspekt der Zeit – und Kosteneffizienz. Dabei sollen spezifische Probleme bei der Berechnung der Breitenlastverteilung über der Zahnflanke für doppelschrägverzahnte Planetengetriebe erfasst werden. Diese Probleme umfassen bei Doppelschrägverzahnung beispielsweise die hohen Torsionsverformungen, die Aufteilung der Last auf die Zahnhälften und die gegenseitige Beeinflussung der Verformung der Zahnhälften untereinander
Porous Ultra Low-k Material Integration Through An Extended Dual Damascene Approach: Pre-/ Post-CMP Curing Comparison
Get PDFIntegration of dielectrics with increased porosity is required to reduce the capacitance of interconnects. However, the conventional dual damascene integration approach is causing negative effects to these materials avoiding their immediate implementation. A post-CMP curing approach could solve some of these issues. However, materials with porogens being stable at temperatures of the barrier-seed deposition process are not common, hindering this approach. Here, we report on an extended dual-damascene integration approach which permits post-CMP curing
Processing Effect on Via Extrusion for Through-Silicon Vias (TSVs) in 3D Interconnects: A Comparative Study of Two TSV Structures: Processing Effect on Via Extrusion for Through-Silicon Vias (TSVs) in 3DInterconnects: A Comparative Study of Two TSV Structures
Get PDFIn this paper, processing effects of electroplating and post- plating annealing on via extrusion are investigated. The study is based on two TSV structures with identical geometry but different processing conditions. Via extrusion, stress and material behaviors of the TSV structures were first compared. Electron backscatter diffraction (EBSD) and time-of-flight secondary ion mass spectroscopy (TOF-SIMS) were used to characterize the microstructure of TSVs and the additives incorporated during electroplating. Based on the results, processing effects on via extrusion and its mechanism are discussed, including grain growth, local plasticity, and diffusional creep
Survey of Expert Opinion on Intelligence: Causes of International Differences in Cognitive Ability Tests
Get PDFFollowing Snyderman and Rothman (1987, 1988), we surveyed expert opinions on the current state of intelligence research. This report examines expert opinions on causes of international differences in student assessment and psychometric IQ test results. Experts were surveyed about the importance of culture, genes, education (quantity and quality), wealth, health, geography, climate, politics, modernization, sampling error, test knowledge, discrimination, test bias, and migration. The importance of these factors was evaluated for diverse countries, regions, and groups including Finland, East Asia, sub-Saharan Africa, Southern Europe, the Arabian-Muslim world, Latin America, Israel, Jews in the West, Roma (gypsies), and Muslim immigrants. Education was rated by N = 71 experts as the most important cause of international ability differences. Genes were rated as the second most relevant factor but also had the highest variability in ratings. Culture, health, wealth, modernization, and politics were the next most important factors, whereas other factors such as geography, climate, test bias, and sampling error were less important. The paper concludes with a discussion of limitations of the survey (e.g., response rates and validity of expert opinions)
Dynamic Architectural Simulation Model of YellowCar in MATLAB/Simulink Using AUTOSAR System
Get PDFThe YellowCar at the professorship of computer engineering of TU Chemnitz is a demonstration vehicle. The car is equipped with multiple networked Electronic Control Unit (ECU)s. There are regular software and hardware updates. Before introduction of any new update, it is essential to test the behavior of the car. This can be done through simulation. Since the majority of the ECU in YellowCar are AUTOSAR based, several AUTOSAR simulation tools can be used to do so. However non-AUTOSAR ECU applications can still not be simulated in these tools. Moreover simulating with such tools need the whole application to be implemented and also very expensive. Simulink is one of the most powerful tools for the purpose of Model-in-the-Loop (MIL) testing which is a popular strategy in the embedded world. The scope of this Master thesis is analyzing the YellowCar and its architecture to develop a dynamic Simulink architectural model that can be modified and extended to facilitate future updates. The outcome of this thesis is an implementation of a model for the YellowCar which allows both AUTOSAR and non-AUTOSAR ECUs to be simulated as one system. Also the model supports extension by easy addition of new modules like ECU or sensor through a graphical user interface
Contact-Less High Speed Measurement over Ground with 61 GHz Radar Sensor
No full textConventional FMCW radar principle was implemented on Symeo 61 GHz LPR®-1DHP-R radar sensor system. There were few limitations of the FMCW implementation which needed to be removed. First, target separation in multi target environment was not possible for objects at same distance. For example, there are two targets, one is moving and one is static. When the moving target approaches the static target and becomes parallel to static target, which means they are at the same distance. At this point, the system is unable to distinguish between two targets. Second, high resolution in velocity measurement was needed. To overcome these limitations Range Doppler Signal Processing was proposed.
For the implementation of the Range Doppler algorithm, first of all proof of concept is needed. Simulations are performed using MATLAB to simulate Range Doppler algorithm using raw data from the sensor. After successful simulation, prototype is developed using python. This also provides the real time visualization of Range Doppler signal processing along with peak detection with distance and velocity measurements. With the Range Doppler implementation, separation between static and moving target becomes possible. Later the algorithm is implemented on Texas Instrument DSP in C considering the resource limitations of the target hardware.
To validate the Range Doppler implementation and to determine the measurements accuracy, multiple test setups are created. Two main local testing environments have been setup, linear unit and turntable. The system is tested on these environments for different velocities and distances along with multiple targets and on different surfaces. Furthermore, the system is tested at an industrial site for detecting the fluid speed, which is also possible with the Range Doppler implementation
Concept and Implementation of AUTOSAR compliant Automotive Ethernet stack on Infineon Aurix Tricore board
Get PDFAutomotive Ethernet is a newly introduced in-vehicle bus that allows unicast communication between ECUs. It is based on the OSI model of Ethernet, with a few modifications on the physical layer and newly introduced application protocols. AUTOSAR, a consortium of automotive OEMs, Tier-1 suppliers and tool vendors has defined a standard software architecture that simplifies the ECU software development with its well defined software specifications and APIs. The Automotive Ethernet stack is now an integral part of the latest AUTOSAR specification release 4.2. Infineon Aurix TriCore TC27x microcontroller is a popular board used in ADAS applications. The board has support for Fast Ethernet. This thesis investigates the setting up of an Ethernet communication on the TriCore board running under AUTOSAR software architecture. The various modules of the AUTOSAR Ethernet stack are familiarized and configured. This is followed up by validating the implementation on the Ethernet physical layer. The validation is based on a real Ethernet communication between the TriCore board and the Vector VN5610 network interface card. TCP and UDP based connections between the AUTOSAR compliant board and the VN5610 are tested and validated. A test suite for evaluating the protocol conformance of the AUTOSAR Ethernet stack exists at Bertrandt. The final step of this thesis involved the execution strategies for this test suite