Signal processing architectures for automotive high-resolution MIMO radar systems

To date, the digital signal processing for an automotive radar sensor has been handled in an efficient way by general purpose signal processors and microcontrollers. However, increasing resolution requirements for automated driving on the one hand, as well as rapidly growing numbers of manufactured sensors on the other hand, can provoke a paradigm change in the near future. The design and development of highly specialized hardware accelerators could become a viable option - at least for the most demanding processing steps with data rates of several gigabits per second. In this work, application-specific signal processing architectures for future high-resolution multiple-input and multiple-output (MIMO) radar sensors are designed, implemented, investigated and optimized. A focus is set on real-time performance such that even sophisticated algorithms can be computed sufficiently fast. The full processing chain from the received baseband signals to a list of detections is considered, comprising three major steps: Spectrum analysis, target detection and direction of arrival estimation. The developed architectures are further implemented on a field-programmable gate array (FPGA) and important measurements like resource consumption, power dissipation or data throughput are evaluated and compared with other examples from literature. A substantial dataset, based on more than 3600 different parametrizations and variants, has been established with the help of a model-based design space exploration and is provided as part of this work. Finally, an experimental radar sensor has been built and is used under real-world conditions to verify the effectiveness of the proposed signal processing architectures.Bisher wurde die digitale Signalverarbeitung für automobile Radarsensoren auf eine effiziente Art und Weise von universell verwendbaren Mikroprozessoren bewältigt. Jedoch können steigende Anforderungen an das Auflösungsvermögen für hochautomatisiertes Fahren einerseits, sowie schnell wachsende Stückzahlen produzierter Sensoren andererseits, einen Paradigmenwechsel in naher Zukunft bewirken. Die Entwicklung von hochgradig spezialisierten Hardwarebeschleunigern könnte sich als eine praktikable Alternative etablieren - zumindest für die anspruchsvollsten Rechenschritte mit Datenraten von mehreren Gigabits pro Sekunde. In dieser Arbeit werden anwendungsspezifische Signalverarbeitungsarchitekturen für zukünftige, hochauflösende, MIMO Radarsensoren entworfen, realisiert, untersucht und optimiert. Der Fokus liegt dabei stets auf der Echtzeitfähigkeit, sodass selbst anspruchsvolle Algorithmen in einer ausreichend kurzen Zeit berechnet werden können. Die komplette Signalverarbeitungskette, beginnend von den empfangenen Signalen im Basisband bis hin zu einer Liste von Detektion, wird in dieser Arbeit behandelt. Die Kette gliedert sich im Wesentlichen in drei größere Teilschritte: Spektralanalyse, Zieldetektion und Winkelschätzung. Des Weiteren werden die entwickelten Architekturen auf einem FPGA implementiert und wichtige Kennzahlen wie Ressourcenverbrauch, Stromverbrauch oder Datendurchsatz ausgewertet und mit anderen Beispielen aus der Literatur verglichen. Ein umfangreicher Datensatz, welcher mehr als 3600 verschiedene Parametrisierungen und Varianten beinhaltet, wurde mit Hilfe einer modellbasierten Entwurfsraumexploration erstellt und ist in dieser Arbeit enthalten. Schließlich wurde ein experimenteller Radarsensor aufgebaut und dazu benutzt, die entworfenen Signalverarbeitungsarchitekturen unter realen Umgebungsbedingungen zu verifizieren

Electronic Complaints : An Empirical Study on British English and German Complaints on eBay

Cross-cultural differences in computer-mediated communication (CMC) have received little attention so far, especially with regard to complaining behaviour. It is therefore the aim of the present study to contribute to this still unexplored research area by comparing British English and German complaints in CMC, precisely on eBay. This study is thus anchored in the field of cross-cultural pragmatics, and the main approach taken is speech-act based. However, since complaints are always embedded in discourse and therefore occur as post-event, the present investigation also takes the contextual factors of the data into account, thus additionally drawing on research from discourse analysis. The overall aim of this study is a comparison of the British English and German production of computer-mediated complaints and, consequently, a description of similarities and differences, of which the latter may lead to misunderstandings in cross-cultural electronic communicative situations. Specifically, the collected complaints were analysed according to five categories: the use of complaint strategies, the chosen level of directness, the employment of modification, the use of pronouns, and the handling of CMC features. In the light of these categories, the following research questions guided the investigation: Do British and German traders’ computer-mediated complaints differ with regard to the five categories of analysis? Does the reason for complaining influence their linguistic choices? Does it make a difference whether they have one or two reasons for their online complaint? In order to find answers to these research questions, British English and German complaints were taken from the British and German feedback forum of the online auction house eBay and analysed according to the five categories. The results were then statistically compared. The findings of this project show both similarities and differences in the way British English and German eBay users formulate their online complaints. Differences become apparent with regard to all five categories under investigation. Furthermore, the results illustrate that both factors, i.e. the particular type of reason and the number of reasons for an online complaint, have an impact on the complaining behaviour of both British English and German users of eBay’s feedback forum. When comparing these findings with previous research on complaints in spoken communication, the results of the present study suggest that the language modality has an impact on how traders formulate their complaints. Moreover, in the light of current (im)politeness theories, the present discussion shows that, if the context of the interaction as well as the communicative norms of appropriateness are included in the investigation of polite, impolite and politic behaviour, the analysis becomes much more complex. Accordingly, behaviour which constitutes impoliteness in the view of traditional politeness frameworks, must often be judged as appropriate, given the specific norms. To conclude, the present study gives initial insight into British English and German complaining behaviour on eBay and will hopefully provide researchers with an incentive to pursue further research in this direction in the near future.  </p

NFC based service innovation in retail: An explorative study

Enterprises are facing a challenging dilemma. In order to be able to accommodate peak loads on their IT systems, they must maintain large computing clusters, which lie idle most of the time. At the same time, IT departments are under constant pressure to cut down on hard- and software expenses. Grid technology offers a promising way out of this dilemma by allowing the dynamic sharing both within enterprises as well as across organizational boundaries. This sharing approach, however, requires proper economic incentives. This paper is concerned with the determination of dynamic market-based prices. Due to their simplicity, so-called pay-as-bid mechanisms have become popular. This paper is novel as we provide an in-depth analysis of two such pay-as-bid mechanisms – Proportional Share and a discriminatory pay-as-bid mechanism – for the case of three users, thus extending previous work by Sanghavi and Hajek (2004) and Stößer et al. (2008). This analysis is important as we show that the nice results for two users cannot be retained once three or more users are present. Even worse, we show that these results can even be reversed if we move to games with more than two player

Coordinating service composition

The fundamental paradigm shift from traditional value chains to agile service value networks implies new economic and organizational challenges. As coordination mechanisms, auctions have proven to perform quite well in situations where intangible and heterogeneous goods are traded. Nevertheless traditional approaches in the area of multiattribute combinatorial auctions are not quite suitable to enable the trade of composite services. A flawless service execution and therefore the requester\u27s valuation highly depends on the accurate sequence of the functional parts of the composition, meaning that in contrary to service bundles, composite services only generate value through a valid order of their components. We present an abstract model as a formalization of a service value network. The model comprehends a graph-based mechanism design to allocate multiattribute service offers within the network, to impose penalties for non-performance and to determine prices for complex services. The mechanism and the bidding language support various types of QoS attributes and their (semantic) aggregation. We analytically show that this variant is incentive compatible with respect to all dimensions of the service offer (quality and price)

Multipath Key Reinforcement in Weitverkehrsnetzen

Durch die drohende Existenz von praktikablen Quantencomputern steigt das Verlangen nach quantenresistenten Schlüsselaustauschprotokollen immer weiter. Vor allem in Weitverkehrsnetzen (WANs) ist das Absichern der Kommunikation entscheidend. Dabei setzt der momentane Stand der Wissenschaft auf die Post-Quanten-Kryptographie (PQC). Verfahren aus dieser Klasse haben aber entscheidende Nachteile: das Vertrauen in die Sicherheit fehlt oder die Performance ist im Vergleich zu etablierten Verfahren schlecht. Die Nachteile schließen sich dabei nicht gegenseitig aus. Aufgrund dessen wurde im Rahmen dieser Arbeit ein Schlüsselaustauschprotokoll entwickelt, welches auf Verfahren aus der PQC verzichtet. Das Verfahren bestimmt dabei möglichst viele Pfade, über die jeweils eine Zufallszahl ausgetauscht wird. Diese Zufallszahlen werden dann zu einem gemeinsamen Schlüssel abgeleitet. Die Erkundung der Wege ist dabei die zentrale Aufgabe des Protokolls, da sich die Sicherheit auf die Diversität und Anzahl der Pfade stützt, und wird mithilfe von begrenzten Fluten gelöst. Zusätzlich kann das Protokoll die erreichte Sicherheit automatisiert bewerten. Ein Quantencomputer stellt dabei keine große Bedrohung dar, da ein Angreifer alle Pfade kompromittieren muss, um den Schlüssel abzuleiten. Das Konzept wird dabei in ein VPN-Autokonfigurationsnetz integriert. Mithilfe einer Simulation wird dann das Konzept evaluiert, um die Eigenschaften Skalierbarkeit, Robustheit und Sicherheit zu untersuchen. Das entwickelte Konzept bietet dabei zusätzlich zu der Quantenresistenz hohe Robustheit gegenüber dynamischen Änderungen im Netz, logarithmische Abhängigkeit der Paketgröße von der Netzgröße und eine hohe Diversität der Pfade.Due to the threatened existence of practicable quantum computers, the demand for quantum-resistant key exchange protocols continues to grow. Securing communication is particularly important in wide area networks (WANs). The current state of science relies on post-quantum cryptography (PQC). However, algorithms from this class have significant disadvantages: there is no trust in security or the performance is poor compared to established algorithms. The disadvantages are not mutually exclusive. Because of this, a key exchange protocol was developed in this work, which does not use PQC algorithms. The method determines as many paths as possible, each of which is used to exchange a random number. These random numbers are then used to derive a key. Exploring paths is the central task of the protocol, since security relies on the diversity and number of paths and is solved with the help of limited flooding. In addition, the protocol can automatically evaluate the achieved security. A quantum computer does not represent a major threat because an attacker would have to compromise all paths in order to derive the key. The concept is integrated into a VPN auto-configuration network. With the help of a simulation the concept is then evaluated in order to examine the properties of scalability, robustness and security. In addition to the quantum resistance, the developed concept offers high robustness against dynamic changes in the network, logarithmic dependency of the packet size on the network size and a high diversity of the paths

Recurrence of disease activity during pregnancy after cessation of fingolimod in multiple sclerosis

Background: Fingolimod is an effective treatment for active relapsing-remitting multiple sclerosis (MS). Discontinuation of therapy may be followed by recurrence of disease activity. Thus, female MS patients may be at risk of relapse during pregnancy after stopping fingolimod. Objectives and methods: To report the disease course during pregnancy of five women who interrupted therapy with fingolimod for pregnancy. Results: All patients experienced relapses during pregnancy and/or postpartum after stopping fingolimod. Conclusion: The risk of recurrence of disease activity during pregnancy after stopping fingolimod may be substantial. This should be considered and discussed with MS patients who are planning to become pregnant

The application of dental age estimation methods

Die Studie “The chronology of third molar mineralization in the Austrian population—a contribution to forensic age estimation” legt Referenzdaten zur Mineralisation des dritten Molaren in der österreichischen Population vor. Im Rahmen dieser Querschnittsuntersuchung wurden Panoramaröntgenaufnahmen von 610 ÖsterreicherInnen im Alter zwischen 12 und 24 Jahren gemäß dem 8-gradigen Entwicklungsschema nach Demirjian et al. (1973) beurteilt. Es wurde festgestellt, dass 78,2% der beurteilten Individuen beide mandibulären Molaren besaßen; bei 11,3% der Subjekte wurde ein unterer dritter Molar erfasst. Bisherige Erfahrungen über den zeitigeren Beginn der Weisheitszahnmineralisation bei Frauen wurden bestätigt. Ein statistisch signifikanter Sexualdimorphismus wurde in den Stadien E (p<0,01) und F (p<0,05) nach Demirjian beobachtet. Weiters wurde die Wahrscheinlichkeit eines österreichischen Individuums ermittelt wenigstens 18 Jahre alt zu sein. Waren beide mandibulären Molaren vorhanden, so betrug die Wahrscheinlichkeit wenigstens 18 Jahre alt zu sein 99,5 bzw. 99,3 % für Männer bzw. für Frauen, jeweils im Falle der vollendeten Zahnmineralisation (Stage H nach Demirjian). Dies legt nahe, dass Demirjians Stage H eine wertvolle Hilfe in der dentalen Altersschätzung darstellt. Die gewonnenen Daten sind ausschließlich für österreichische Individuen gültig und können nicht zur Altersschätzung in anderen Populationen herangezogen werden. Gemäß den Empfehlungen der interdisziplinären Arbeitsgemeinschaft für Forensische Altersdiagnostik inkludiert eine Altersbestimmung am Lebenden außerdem ein Handröntgen sowie eine körperliche Untersuchung. Die Autorin befürwortet eine kombinierte Technik die dazu beiträgt, inkorrekte Altersschätzungen aufgrund der biologischen Varianz eines einzelnen Merkmals zu vermeiden. Trotzdem fehlt noch immer eine große Studie, welche die Verwendung der Methodenkombination validiert, obwohl sich selbige bereits in Verwendung befindet. Die zweite Untersuchung “On the applicability of secondary dentin formation to radiological age estimation in young adults” untersuchte, ob bisher publizierte Regressionsgleichungen zur dentalen Altersschätzung, basierend auf radiographischen, zweidimensionalen Messungen der Pulpagröße, zu reproduzierbaren und korrekten Ergebnissen führen. Es wurden Panoramaröntgenaufnahmen von 44 österreichischen Individuen, im Alter zwischen 13 und 24 Jahren, ausgesucht um die Messungen nach Kvaal et al. (1995) vorzunehmen. Die Verwendung der Regressionsgleichung von Paewinsky et al. (2005) führte zu einer konsistenten Überschätzung, die Gleichungen nach Kvaal et al. (1995) resultierten in einer konstanten Unterschätzung des Alters. Aufgrund dieser Ergebnisse kann gefolgert werden, dass die Formeln The Application of Dental Age Estimation Methods Zusammenfassung auf Deutsch 93 nach Kvaal et al. (1995) und Paewinsky et al. (2005) für die dentale Altersschätzung junger Erwachsener nicht geeignet sind. Es wird empfohlen Sekundärdentinbildung anhand einer großen Stichprobe der vorliegenden Altersgruppe zu evaluieren um verlässliche Referenzdaten hierzu erhalten. Weiters könnte es hilfreich sein, die Verminderung der Pulpagröße anhand zusätzlicher Parameter, wie von Cameriere et al. (2007b) vorgeschlagen zu ermitteln, oder aber mittels Computertomographie (Yang et al. 2006). Die dritte Studie „Comparison of the validity of three dental methods for the estimation of age at death“ konzentrierte sich auf den Vergleich der Genauigkeit, des Bias sowie der Praktikabilität zweier makroskopischer und einer histologischen dentalen Methode zur Schätzung des Sterbealters. Die Stichprobe bestand aus 67 Zähnen von 37 Individuen im Alter zwischen 20 und 91 Jahren. Die Schätzung des chronologischen Alters erfolgte gemäß den Methoden nach Lamendin et al. (1992) (LAM), Bang and Ramm (1970) (BR), sowie der Quantifizierung von Zahnzementannulationen (TCA). Die höchste Genauigkeit des Schätzergebnisses zeigte die TCA- Methode bei Zähnen der jungen, mittleren und alten Altersgruppe. LAM zeigte die höchste Präzision in der jungen und alten Altersgruppe, wohingegen sich in der mittleren Altersgruppe TCA als präziser erwies. TCA war die präziseste Methode, sofern die Altersgruppen nicht getrennt analysiert wurden. Bezüglich des Bias hatten alle Methoden die Tendenz das Alter in jungen Proben zu überschätzen, sowie in alten Proben zu unterschätzen. Die Ausnahme war hier TCA, die junge Erwachsene ohne Bias schätzte. Aufgrund der höheren Genauigkeit und Präzision wird es empfohlen die TCA-Methode LAM und BR vorzuziehen, sofern entsprechendes Wissen und Ausstattung vorhanden sind. Weitere Studien in Bezug auf den genauen Mechanismus und die Chronologie der Zahnzementannulationen, der Sekundärdentinapposition, sowie der Dentintransparenz würden die Genauigkeit von Altersschätzungen verbessern. Weiters wäre eine allgemein anerkannte Prozedur zur Präparation und Evaluation von Zahnzementannulationen wünschenswert um einen gemeinsamen Standard zu etablieren.The study “The chronology of third molar mineralization in the Austrian population—a contribution to forensic age estimation” provides reference data on third molar mineralization in the Austrian population. Within the present cross-sectional evaluation panoramic radiographs of 610 Austrians between 12 and 24 years of age were assessed using the 8 developmental stages of Demirjian et al. (1973). It was found that 78.2% of the analyzed individuals possessed both mandibular third molars; 11.3% of the subjects were recorded to have one lower third molar. Previous records about an earlier occuring third molar mineralization in females were confirmed. A statistically significant sexual dimorphism was noted in Demirjian’s stages E (p<0.01) and F (p<0.05). A comparison with previous study data suggests ethnic differences in the timing of third molar mineralization. Moreover, the probability of whether an Austrian individual is at least 18 years old was determined. In the case where two mandibular third molars were present, the probability for an Austrian individual to be at least 18 years is 99.5% and 99.3% for males and females, respectively in the case were tooth mineralization is completed (Demirjian’s stage H). This indicates that Demirjian’s stage H constitutes a reliable aid in dental age estimation. The obtained data is exclusively valid in Austrian individuals and cannot be used for dental age estimation in other populations. According to the recommendations of the interdisciplinary Study Group on Forensic Age Diagnostics, an age analysis of living persons also includes an X-ray of the hand and a physical examination. The author supports a combined technique that helps to avoid incorrect age estimates due to the biological variance of a single trait. Nonetheless, a large study that validates the use of the combination of methods is still lacking although this procedure is already in use. The second investigation “On the applicability of secondary dentin formation to radiological age estimation in young adults” aimed to explore whether previously published regression formulae for dental age estimation based on radiographic two-dimensional measurements of the pulp size lead to reproducible and statistically sound results. Panoramic radiographs of 44 Austrian individuals, aged between 13 and 24 years, were selected to carry out the measurements proposed by Kvaal et al. (1995). The use of the regression formulae reported by Paewinsky et al. (2005) led to a consistent overestimation, the equations of Kvaal et al. (1995) resulted in a constant underestimation of age. From these results it can be concluded that the formulae of Kvaal et al. (1995) and Paewinsky et al. (2005) are not suitable for dental age The Application of Dental Age Estimation Methods Summary of the Results and Outlook 91 estimation in young adults. It is suggested to evaluate secondary dentin formation with a large sample size in the present age group to obtain reliable reference data. Furthermore, it could be helpful to assess the decrease of the pulp size also by additional parameters as proposed by Cameriere et al. (2007b) or via computerized tomography (Yang et al. 2006). The third study “Comparison of the validity of three dental methods for the estimation of age at death” focused on the comparison of accuracy, bias, and practicability of two macroscopic and one histological dental age at death estimation methods. The study sample comprised of 67 teeth, obtained from 37 individuals aged 20 to 91 years. Chronological age was estimated by means of the methods proposed by Lamendin et al. (1992) (LAM), Bang and Ramm (1970) (BR), and the quantification of tooth cementum annulations (TCA). TCA was found to be the most accurate age at death estimation method in young, middle, and old age group teeth. LAM displayed the highest precision in the young, and the old age group whereas TCA was more precise in the middle age group. TCA showed to be the most precise method when the precision was calculated for all ages. Considering the bias, all methods displayed a tendency to overestimate age in young and to underestimate it in old specimens. The exception to this rule was TCA, which provided unbiased estimates for young adults. The higher accuracy and precision recommends favouring TCA over LAM and BR, provided that the required knowhow and equipment are available. Further studies in order to assess the exact mechanism and timing of tooth cementum layering, secondary dentin apposition, and dentin sclerosis would be helpful to improve the accuracy of age estimates. Moreover, a generally accepted procedure for the preparation and evaluation of root cementum annulations would be desirable to establish common standards