The architecture of the network is undergoing a series of structural changes from the core network to the user to pave the way for 5G. New infrastructure elements are being massively deployed, thus making 5G more heterogeneous. This emerging paradigm, along with new services and handheld devices, creates a massive, highly mobile, heterogeneous environment with hard constraints in throughput, latency, resilience, and power consumption. This dissertation presents Agile MEC (AMEC), a shift in the concept of MEC to support user's mobility with the rapid relocation of services; and Network-coded Cooperation (NCC), a new system for massive content distribution in cellular networks. In summary, AMEC provides a mobility framework that reliably reduces the latency and power consumption in the system, and NCC improves network throughput, network resilience, and power consumption by offloading cellular traffic to underlay networks. / Die Architektur des Netzes durchläuft eine Reihe von strukturellen Veränderungen vom Kernnetz bis zum Benutzer, um den Weg für 5G zu ebnen. Neue Infrastruktur Elemente werden massiv eingesetzt, wodurch 5G heterogener wird. Dieses aufkommende Paradigma bildet zusammen mit neuen Diensten und Handheld-Geräten eine massive, hochmobile, heterogene Umgebung mit harten Einschränkungen in Bezug auf Durchsatz, Latenz, Belastbarkeit und Stromverbrauch. In dieser Dissertation werden Agile MEC (AMEC), eine Verschiebung des MEC-Konzepts zur Unterstützung der Mobilität der Benutzer durch die schnelle Verlagerung von Diensten, und Network-coded Cooperation (NCC), ein neues System zur massiven Verteilung von Inhalten in zellularen Netzwerken, vorgestellt. Zusammenfassend lässt sich sagen, dass AMEC einen Mobilitätsrahmen bietet, der die Latenzzeit und den Stromverbrauch im System zuverlässig reduziert, und NCC verbessert den Netzwerkdurchsatz, die Netzwerkstabilität und den Stromverbrauch, indem es den zellularen Datenverkehr auf unterlagerte Netzwerke verlagert.

Laseroptische Messsysteme werden vielseitig eingesetzt, unter anderem für die Messung der Strömung in Blasen und Tropfen. Beispielsweise ist die Messung in Tropfen von besonderem Interesse für die Brennstoffzellenforschung, da das Wasserkondensat die Leistungsfähigkeit der Zelle stark mindern kann. Bei der laseroptischen Messung durch die dynamische Phasengrenzfläche erhöht sich aufgrund der zufälligen Lichtbrechung die Messunsicherheit erheblich. Um dem entgegenzuwirken, wurde in dieser Arbeit untersucht, wie sich der in der Astronomie weitverbreitete Ansatz einer aktiven Wellenfrontkorrektur auf die laseroptische Strömungsmesstechnik für die Korrektur einer zufällig dynamisch streuenden Phasengrenzfläche mit nur einem optischen Zugang durch die Grenzfläche übertragen lässt. Als neuartiger Leitstern wurde hierfür der Fresnel-Reflex der Oberfläche als Fresnel Guide Star (FGS), welcher alle Informationen über die optische Störung enthält, untersucht und eingesetzt. Validiert wurde der neue Leitstern exemplarisch für die zwei laseroptischen Messverfahren Laser-Doppler-Velocimetrie (LDV) und Particle-Image-Velocimetrie (PIV). Für das bildgebende Messverfahren PIV wurde ein Regelsystem realisiert, welches eine adaptive optische Korrektur einer oszillierenden Wasseroberfläche durchführt. Das System besteht aus einem Hartmann-Shack-Sensor (HSS), einer Signalverarbeitungseinheit und einem 69-elementigen deformierbaren Membranspiegel. Dabei muss die Signalverarbeitungseinheit aus dem Hartmannogramm die Wellenfront des FGS rekonstruieren, die Stellgröße berechnen und den Membranspiegel ansteuern. Diese komplexe Multiple-Input-Multiple-Output(MIMO)-Regelungsaufgabe stellt besondere Anforderungen an das System, da die Wasseroberfläche mit mehreren hundert Hertz schwingt und das System für eine hinreichende Reserve somit eine Regelrate im Kilohertzbereich haben muss. Um diese Anforderungen zu erfüllen, wurde als hybride Recheneinheit ein Field- Programmable System-on-Chip (FPSoC) eingesetzt. Dieser vereint eine Central Processing Unit (CPU) und einen Field-Programmable Gate Array (FPGA) auf einem einzigen monolithischen Chip als eine sehr leistungsfähige Symbiose beider Architekturen. Das System erreicht eine Regelrate von 3,5 kHz und war in der Lage, die optische Störung mit einer Dämpfungsbandbreite von bis zu 150 Hz zu dämpfen. Bei der PIV-Messung wurde die Erhöhung der Standardunsicherheit des Geschwindigkeitsfeldes, verursacht durch die Oszillation der Phasengrenzfläche, um 67 % reduziert. Das System kann beispielsweise für die Optimierung von Brennstoffzellen eingesetzt werden, um die Tropfeninnenströmung in den auf der chemisch aktiven opaken Membran kondensierten Tropfen mit nur einem einzigen optischen Zugang durch die streuende Grenzfläche zu messen. Damit könnte der Gleitprozess des Tropfens an der Membranoberfläche verstanden werden und das Wasser effektiver abtransportiert werden, um die Leistungsfähigkeit der Zelle zu steigern. Weitere Anwendungsgebiete sind die Strömungsmessung in Taylorblasen, Regentropfen oder Flüssigkeitskühlfilmen mit offener Oberfläche. Generell hat der neue FGS zusammen mit dem Regelungssystem das Potenzial, die optische Messung durch eine dynamische oszillierende Grenzfläche zu verbessern oder überhaupt erst zu ermöglichen. / Laser optical measurement systems are used in a variety of applications, e.g. the flow measurement in bubbles and droplets. The flow in droplets is of particular interest for fuel cell research, since water condensate can significantly reduce the efficiency of the cell. In laser-optical measurements the dynamic motion of the phase boundary increases the measurement uncertainty significantly because of the random refraction of light. Therefore this thesis investigates how the approach of an active wavefront correction, which is widely used in astronomy, can be applied to laser-optical flow measurement techniques for the correction of a dynamic phase boundary with only one optical access through the interface. For this purpose, the Fresnel reflection of the surface was investigated, which is called Fresnel Guide Star (FGS). It contains all information about the optical distortion. The new guide star was validated exemplarily for the two laser optical measurement techniques Laser Doppler Velocimetry (LDV) and Particle Image Velocimetry (PIV). For PIV a control system consisting of a Hartmann-Shack-Sensor (HSS), a signal processing unit and a 69-element deformable membrane mirror was realized, which performs an adaptive optical correction of the moving water surface. Therefore the signal processing unit must reconstruct the wavefront of the FGS from the Hartmannogram, calculate the set value and control the membrane mirror. This complex Multiple-Input Multiple-Output (MIMO) control task results in extensive demands on the control system, since the water surface oscillates with several hundred hertz and the system must therefore have a control rate in the kilohertz range to ensure sufficient reserve. In order to meet these requirements, a Field- Programmable System-on-Chip (FPSoC) was used as hybrid computing unit. It combines a Central Processing Unit (CPU) and an Field-Programmable Gate Array (FPGA) on a single monolithic chip as a very powerful symbiosis of both architectures. The system achieved a control rate of 3,5 kHz and was able to attenuate the optical distortion with an attenuation bandwidth of up to 150 Hz. In the PIV measurement, the increase in the standard uncertainty of the velocity field caused by the oscillation of the phase boundary was reduced by 67 %. The system could be used for the optimization of fuel cells to measure the internal flow in the droplets condensed on the chemically active membrane with only one optical access through the fluctuating interface. This would allow the sliding process of the droplet on the membrane surface to be understood and the water to be removed more effectively in order to increase the performance of the cell. Further applications are flow measurement in bubbles, raindrops or liquid cooling films with an open surface, where the system expands the field of application for computational laser metrology. In general, the new FGS together with the low latency control system have the potential to improve the optical measurement through dynamically oscillating interfaces or to make the measurement possible at all.

This work presents an analogue baseband (BB) chain for a magnetic tunneling junction (MTJ) based radiofrequency (RF) signal detector fully integrated in a hybrid CMOS-MTJ technology. The BB chain contains a 6 th -order gm-C low-pass filter (LPF), a BB amplifier, a comparator, and a current bank. According to measurement results, the 6 th -order LPF with a cut-off frequency of 10 MHz consumes a very low DC power of 2.41 mW. Its DC power consumption per pole of 0.4 mW is the lowest among the state-of-the-art LPFs. The LPF can be also switched on and off very fast within 110 ns. With the fast switch-ability and the low power consumption, the LPF outperforms the state of the art. Furthermore, the complete BB chain can transform a 2.5 Vpp, 5 Mbps BB signal into digital data with a bit error rate fewer than 1e−6 . The BB chain consumes 2.85mW including all bias circuits. To achieve power efficiency, the BB chain is designed to operate under an aggressive duty-cycling mode. The switch-on time of the BB chain is within 200 ns

Random Linear Network Coding (RLNC) is a new coding technique which can provide higher reliability and efficiency in wireless networks. Applying it on the fifth generation of cellular networks (5G) is now possible due to the softwarization approach of the 5G architecture. However, the complex computations necessary to encode and decode symbols in RLNC are limiting the achievable throughput and energy efficiency on todays mobile computers. Most computers, phones, TVs, or network equipment nowadays come with multiple, possibly heteregoneous (i.e. slow low-power and fast high-power) processing cores. Previous multi core research focused on RLNC optimization for big data chunks which are useful for storage, however network operations tend to use smaller packets (e.g. Ethernet MTUs of 1500 byte) and code over smaller generations of packets. Also latency is an increasingly important performance aspect in the upcoming Tactile Internet, however latency has received only small attention in RLNC optimization so far. The primary research question of my thesis is therefore how to optimize throughput and delay of RLNC on todays most common computing architectures. By fully leveraging the resources of todays consumer electronics hardware, RLNC can be practically adopted in todays wireless systems with just a software update and improve the network efficiency and user experience. I am generally following a constructive approach by introducing algorithms and methods, and then demonstrating their performance by benchmarking actual implementations on common consumer electronics hardware against the state of the art. Inspired by linear algebra parallelization methods used in high performance computers (HPC), I’ve developed a RLNC encoder/decoder which schedules matrix block tasks for multiple cores using a directed acyclic graph (DAG) based on data dependencies between the tasks. A non-progressive variant works with pre-computed DAG schedules which can be re-used to push throughput even higher. I’ve also developed a progressive variant which can be used to minimize latency. Both variants are achieving higher throughput performance than the fastest currently known RLNC decoder, with up to three times the throughput for small generation size and short packets. Unlike previous approaches, they can utilize all cores also on heterogeneous architectures. The progressive decoder greatly reduces latency while allowing to keep a high throughput, reducing the latency up to a factor ten compared to the non-progressive variant. Progressive decoders need special low-delay codes to release packets early instead of waiting for more dependent packets from the network. I'm introducing Caterpillar RLNC (CRLNC), a sliding window code using a fixed sliding window over a stream of packets. CRLNC can be implemented on top of a conventional generation based RLNC decoder. CRLNC combines the resilience against packet loss and fixed resource boundaries (number of computations and memory) of conventional generation based RLNC decoders with the low delay of an infinite sliding window decoder. The DAG RLNC coders and the Caterpillar RLNC method together provide a powerful toolset to practically enable RLNC in 5G or other wireless systems while achieving high throughput and low delay as required by upcoming immersive and machine control applications.:1 Introduction 2 Background and Related Work 2.1 Network Delay 2.2 Network Coding Basics 2.3 RLNC Optimization for Throughput 2.3.1 SIMD Optimization 2.3.2 Block Operation Increasing Cache Efficieny with Subblocking 2.3.3 Optimizing Matrix Computations 2.4 Progressive RLNC Decoders 2.5 Sliding Window RLNC 3 Optimized RLNC Parallelization with Scheduling Graphs 3.1 Offline Directed Acyclic Graph (DAG) Scheduling 3.1.1 Blocked LU Matrix Inversion 3.1.2 Scheduling on a DAG 3.1.3 Phase 1: DAG Recording 3.1.4 Phase 2: DAG Schedule Execution 3.1.5 DAG Scheduling vs. Conventional Multithreading 3.1.6 Task Size Considerations 3.1.7 Scheduling Strategies First Task Strategy Task Dependency Strategy Data Locality Strategy Combined Task Dependency and Data Locality Strategy 3.2 Online DAG Scheduling 3.2.1 Online DAG Operation Forward Elimination Backward Substitution Row Swapping 3.2.2 Scheduling on an Online DAG Data Dependency Traversal Online DAG Creating and Task Delegation 3.2.3 Optimizations Stripe Optimization Full Rows Optimization 3.3 Evaluation Setup 3.3.1 Multicore Boards ODROID-XU3 ODROID-XU4 ODROID-XU+E Cubieboard 4 Raspberry Pi 2 Model B 3.3.2 Evaluation Parameters Parameter Settings Matrix Types 3.3.3 Performance Metrics Throughput Delay Energy 3.3.4 Evaluation Methodology 3.4 Evaluation Results 3.4.1 Block Size b 3.4.2 Comparison of Scheduling Strategies 3.4.3 Single Thread Throughput 3.4.4 Multi Thread Throughput 3.4.5 Comparison of Multicore Boards 3.4.6 Energy Consumption 3.4.7 Online DAG vs. Offline DAG Throughput 3.4.8 DAG vs Progressive CD 3.4.9 Delay 3.4.10 Trading Throughput with Delay 3.4.11 Sparse Coefficient Matrices in Online DAG 4 Sliding Window - Caterpillar RLNC (CRLNC) 4.1 CRLNC Overview 4.2 CRLNC Packet Format And Encoding 4.3 CRLNC Decoding 4.3.1 Shifting the Row Echelon Form Same sequence number: s_p = s_d New Packet: s_p > s_d Old Packet: s_p < s_d 4.3.2 Larger Decoding Windows: w_d > w_e 4.3.3 CRLNC Decoding Storage and Computing Requirements 4.4 CRLNC Evaluation 4.4.1 Performance Metrics Packet Loss Probability In-Order Packet Delay 4.4.2 Evaluation Methodology 4.5 Evaluation Results 4.5.1 Packet Loss Probability 4.5.2 In-Order Packet Delay 4.5.3 Tradeoffs for Larger Decoding Windows 4.5.4 Computation Complexity 5 Summary and Conclusion List of Publications Bibliography

Die vorliegende Arbeit beschreibt die Analyse und den Entwurf eines vollintegrierten Empfängers im UHF-Bereich mit dem Ziel, für die Verwendung im Mobilfunkstandard der vierten Generation geeignet zu sein, aber auch eine Einschätzung bezüglich der Anwendbarkeit eines solchen Empfängers für Geräte der fünften Generation vorzunehmen. Bei dem Empfängerkonzept handelt es sich um einen direkt digitalisierenden Empfänger, d.h. das Empfangssignal wird direkt mittels Analog-Digital-Umsetzer digitalisiert und vorher nicht auf eine niedrigere Trägerfrequenz abwärtsgemischt. Der Analogteil eines direkt digitalisierenden Empfängers besteht also nur aus einem LNA und einem ADU. Diese Empfängertopologie stellt hohe Anforderungen an den ADU und bildet deshalb den Fokus dieser Arbeit. Für die Untersuchungen des Empfängerkonzepts wurde sich auf eine Implementierung für niedrige Mobilfunkfrequenzbänder beschränkt, weshalb für den Entwurf festgelegt wurde, eine Trägerfrequenz von 750MHz mit einer Signalbandbreite von 20MHz empfangen und verarbeiten zu können. Der Entwurf erfolgte in einer 28nm CMOS Technologie, sollte flächen- und stromsparend sein, sich aber auch für zukünftige Technologieknoten mit noch höherer Integrationsdichte eignen, ohne die analogen Schaltblöcke gesondert bei der Technologiewahl berücksichtigen zu müssen. Somit konnten integrierte Spulen in der Empfängerkette nicht verwendet werden. Zugleich muss im Empfänger der Alias-Effekt unterdrückt werden. Um diese strengen Rahmenbedingungen ohne exorbitante Stromaufnahme zu erfüllen, kommt als ADU-Topologie nur ein zeitkontinuierlicher Sigma-Delta-Modulator in Frage. Dazu musste das Schleifenfilter des Sigma-Delta-Modulators komplett neu entworfen werden, was u.a. den Entwurf einer einstellbaren hochgütigen aktiven Spule erforderte. Das Empfängerkonzept konnte erfolgreich an der gefertigten Schaltung verifiziert werden, der gemessene dynamische Bereich blieb jedoch weit hinter dem ursprünglich anvisierten Ziel von 84dB zurück. Es konnte lediglich ein dynamischer Bereich von 59dB bei einer Leistungsaufnahme von 36,4mW und einer maximalen Auflösung von 4,5 Bit erreicht werden. Nachfolgende Untersuchungen des Konzepts zeigen aber Lösungsansätze auf, mit denen die Auflösung auf 8,7 Bit und der Dynamikbereich auf 69dB gesteigert werden kann.

Sales market in process industry, especially for chemical, pharmaceutical and food industry, is becoming more and more volatile. Furthermore, the global availability of alternative products shortens the product life cycle. At the same time, the requested volumes depend on strong regional and temporal fluctuations, which are increasingly difficult to predict. To be able to bring product innovations successfully to market, rapid series-production readiness of the prototype is needed. However, the competition after successful approval is increasingly getting tougher. As soon as the product has been accepted by the market, the time necessary to reach sufficient product quantities with required product quality is essential for its profitability. By the end of the product life cycle, the production should be close to the largest remaining sales markets, which means that the production can be shifted accordingly. Classical production processes in process industry do not fulfil these requirements jet. Conti-systems are optimized for a certain production quantity per unit of time, which should not be changed for years, if possible. The higher flexibility of conventional batch plants is associated with unproductive times, for example during conversion. However, modularization of process plants with flexible combinatory design would allow faster turnover times and higher productivity. Individual modules realize standardized production steps and can be combined according to the requested product. Changes to the product are achieved by the exchange of modules, the production quantity can be increased by adding more of the same modules. The integration of a module into an upper classic process control system is laborious using the information models and tools available today. Various aspects of automation, such as human machine interfaces, statuses of sequences or interlocks must be added manually for the visualization and guidance of the module in an upper process control system. However, today's control systems are not prepared to provide the required flexibility of a system based on different modules. This drawback requires a modular plug-and-production methodology. Therefore, an outright modeling of information, beginning with modular and function-oriented integrated engineering is needed. On the one hand, this work considers with a selection of integration aspects, a detailed modeling of this aspects in an information carrier and the integration into the process control level. On the other hand, the concrete selection of one or more descriptive formats is analyzed. For this purpose, a uniform integration architecture and an integration process is described, this allows integration into an upper process control system level. This analysis shows that, with the available descriptive formats, a mapping of the individual integration aspects into an information carrier is possible. It is important to distinguish whether a separate mapping is chosen for each aspect, as chosen by GrapML in the second practical implementation, or whether a uniform format is used for the entire information carrier. The evaluation of the description formats suggests for the use in the information carrier AutomationML. The practical implementation and investigation with AutomationML are already in the scope of the Namur MTP developments and couldn’t therefore investigated deeply in this work. For the most important aspects, the human machine interface as well as the process management, detailed information modeling is available and was checked during implementation. Two different possibilities were presented and discussed for the selection of description formats. To allow flexible extensibility, it is advantageous to choose a description means in which the integration aspects are described separately from each other, independently of the specifically chosen format. A uniform interface within automation systems is required for the needs of the so-called industry 4.0 for the networking and consistency of all components involved throughout the entire life cycle. This work provides the first building blocks of this approach and enables application in process industry but also manufacturing industry.

Für einen sicheren und zuverlässigen Betrieb des gesamten Elektroenergieversorgungs-systems ist der langzeitstabile und möglichst wartungsfreie oder wartungsarme Betrieb jeder einzelnen Komponente wichtig. Eine Wartung aller stromführenden Verbindungen ist aufgrund der Anzahl und ihrer Zugänglichkeit nicht möglich. Eine Großzahl der Verbindungen wird deshalb montiert und muss über die geforderte Lebensdauer der Anlagen von mehreren Jahrzehnten wartungsfrei funktionieren. Um dies gewährleisten zu können, müssen die richtigen Leiter- und Beschichtungswerkstoffe gewählt, eine langzeitstabile Konstruktion vorhanden, die richtige Montage durchgeführt und eine gesicherte Grenztemperatur für die gewünschte Lebensdauer unter Berücksichtigung der Umgebungsbedingungen bekannt sein. In dieser Arbeit werden stromführende Verbindungen betrachtet, die keinen Lichtbogen führen müssen. Es werden die wichtigsten Leiter- und Beschichtungswerkstoffe, die Kontaktphysik insbesondere von Flächenkontakten, der Zusammenhang zwischen mechanischem und elektrischem Kontaktverhalten, die Physik der Alterung und die Wirkung auf das Langzeitverhalten bei unterschiedlichen Einsatz- und Umgebungsbedingungen betrachtet. Basierend auf diesen Erkenntnissen werden genormte Prüfverfahren bewertet und Ansätze zum Weiterentwickeln vorgestellt. Die Erkenntnisse dieser Arbeit basieren auf Ergebnissen, die in 40 Jahren Forschung an der TU Dresden erarbeitet wurden. Als Modellgeometrie für die grundlegenden experimentellen Untersuchungen wurden insbesondere Schrauben¬verbindungen mit Stromschienen verwendet, da diese Verbindungsart eine der am häufigsten verwendeten ist und millionenfach im Elektroenergieversorgungssystem eingesetzt wird.:1 Einleitung 2 Funktion und Anforderung an stromführende Verbindungen 3 Kontaktwerkstoffe 3.1 Leiter 3.2 Beschichten von Leitern 4 Kontaktverhalten von Schraubenverbindungen 4.1 Physikalische Grundlagen zum Flächenkontakt 4.2 Schraubenverbindung mit Stromschienen 4.2.1 Mechanisches Kontaktverhalten 4.2.2 Elektrisches Kontaktverhalten 4.2.3 Zusammenhang elektrisches und mechanisches Kontaktverhalten 4.2.4 Montage stromführender Verbindungen 4.2.5 Verallgemeinern der gewonnenen Erkenntnisse 5 Langzeitverhalten von Schraubenverbindungen 5.1 Alterungsmechanismen 5.1.1 Kraftabbau 5.1.2 Diffusion 5.1.3 Chemische Reaktionen 5.1.4 Reibverschleiß 5.1.5 Elektromigration 5.2 Mathematische Ansätze zum Beschreiben der Alterung 5.3 Experimentell ermittelte Lebensdauerkennlinien 5.3.1 Typische Lebensdauerkennlinie von Schraubenverbindungen 5.3.2 Leiterwerkstoffe - Aluminium, Kupfer und deren Legierungen 5.3.3 Beschichtungswerkstoffe - Silber, Nickel, Zinn 6 Prüfverfahren 7 Zusammenfassung und Ausblick 8 Literaturverzeichnis 9 Abbildungsverzeichnis 10 Tabellenverzeichnis / For a safe and reliable operation of the electric power supply system, the long-term stable and low-maintenance or maintenance-free operation of each component is important. Maintenance of all current-carrying joints is not possible due to their number and accessibility. A large number of joints is installed and must operate during the required life-time of the system of several decades maintenance-free. In order to warrant this, the appropriate conductor and coating material must be selected, a long-term stable construction design must be provided, the correct installation must be guaranteed, and a safe temperature limit for the desired life-time must be known according to the ambient conditions. In this work, non-arcing current-carrying joints are investigated. It considers the most important conductor and coating materials, the physics of surface contacts, the relationship between mechanical and electrical contact behavior, the physics of aging and the effects on the long-term behavior under different conditions of use and environmental conditions. Based on these scientific findings, standardized test methods are evaluated and approaches for further development are presented. The findings of this work are based on the results obtained in 40 years of research at the TU Dresden. As a model geometry for the basic experimental investigations bolted joints with bus bars are used, because this type of joint is one of the most commonly used millions of times in the electric power supply system.:1 Einleitung 2 Funktion und Anforderung an stromführende Verbindungen 3 Kontaktwerkstoffe 3.1 Leiter 3.2 Beschichten von Leitern 4 Kontaktverhalten von Schraubenverbindungen 4.1 Physikalische Grundlagen zum Flächenkontakt 4.2 Schraubenverbindung mit Stromschienen 4.2.1 Mechanisches Kontaktverhalten 4.2.2 Elektrisches Kontaktverhalten 4.2.3 Zusammenhang elektrisches und mechanisches Kontaktverhalten 4.2.4 Montage stromführender Verbindungen 4.2.5 Verallgemeinern der gewonnenen Erkenntnisse 5 Langzeitverhalten von Schraubenverbindungen 5.1 Alterungsmechanismen 5.1.1 Kraftabbau 5.1.2 Diffusion 5.1.3 Chemische Reaktionen 5.1.4 Reibverschleiß 5.1.5 Elektromigration 5.2 Mathematische Ansätze zum Beschreiben der Alterung 5.3 Experimentell ermittelte Lebensdauerkennlinien 5.3.1 Typische Lebensdauerkennlinie von Schraubenverbindungen 5.3.2 Leiterwerkstoffe - Aluminium, Kupfer und deren Legierungen 5.3.3 Beschichtungswerkstoffe - Silber, Nickel, Zinn 6 Prüfverfahren 7 Zusammenfassung und Ausblick 8 Literaturverzeichnis 9 Abbildungsverzeichnis 10 Tabellenverzeichnis

This thesis exploits index modulation techniques to design energy- and spectrum-efficient system models to operate in future wireless networks. In this respect, index modulation techniques are studied considering two different media: mapping the information onto the frequency indices of multicarrier systems, and onto the antenna array indices of a platform that comprises multiple antennas. The index modulation techniques in wideband communication scenarios considering orthogonal and generalized frequency division multiplexing systems are studied first. Single cell multiuser networks are considered while developing the system models that exploit the index modulation on the subcarriers of the multicarrier systems. Instead of actively modulating all the subcarriers, a subset is selected according to the index modulation bits. As a result, there are subcarriers that remain idle during the data transmission phase and the activation pattern of the subcarriers convey additional information. The transceivers for the orthogonal and generalized frequency division multiplexing systems with index modulation are both designed considering the uplink and downlink transmission phases with a linear combiner and precoder in order to reduce the system complexity. In the developed system models, channel state information is required only at the base station. The linear combiner is designed adopting minimum mean square error method to mitigate the inter-user-interference. The proposed system models offer a flexible design as the parameters are independent of each other. The parameters can be adjusted to design the system in favor of the energy efficiency, spectrum efficiency, peak-to-average power ratio, or error performance. Then, the index modulation techniques are studied for large-scale multiple-input multiple-output systems that operate in millimeter wave bands. In order to overcome the drawbacks of transmission in millimeter wave frequencies, channel properties should be taken in to account while envisaging the wireless communication network. The large-scale multiple-input multiple-output systems increase the degrees of freedom in the spatial domain. This feature can be exploited to focus the transmit power directly onto the intended receiver terminal to cope with the severe path-loss. However, scaling up the number of hardware elements results in excessive power consumption. Hybrid architectures provide a remedy by shifting a part of the signal processing to the analog domain. In this way, the number of bulky and high power consuming hardware elements can be reduced. However, there will be a performance degradation as a consequence of renouncing the fully digital signal processing. Index modulation techniques can be combined with the hybrid system architecture to compensate the loss in spectrum efficiency to further increase the data rates. A user terminal architecture is designed that employs analog beamforming together with spatial modulation where a part of the information bits is mapped onto the indices of the antenna arrays. The system is comprised a switching stage that allocates the user terminal antennas on the phase shifter groups to minimize the spatial correlation, and a phase shifting stage that maximizes the beamforming gain to combat the path-loss. A computationally efficient optimization algorithm is developed to configure the system. The flexibility of the architecture enables optimization of the hybrid transceiver at any signal-to-noise ratio values. A base station is designed in which hybrid beamforming together with spatial modulation is employed. The analog beamformer is designed to point the transmit beam only in the direction of the intended user terminal to mitigate leakage of the transmit power to other directions. The analog beamformer to transmit the signal is chosen based on the spatial modulation bits. The digital precoder is designed to eliminate the inter-user-interference by exploiting the zero-forcing method. The base station computes the hybrid beamformers and the digital combiners, and only feeds back the digital combiners of each antenna array-user pair to the related user terminals. Thus, a low complexity user architecture is sufficient to achieve a higher performance. The developed optimization framework for the energy efficiency jointly optimizes the number of served users and the total transmit power by utilizing the derived upper bound of the achievable rate. The proposed transceiver architectures provide a more energy-efficient system model compared to the hybrid systems in which the spatial modulation technique is not exploited. This thesis develops low-complexity system models that operate in narrowband and wideband channel environments to meet the energy and spectrum efficiency demands of future wireless networks. It is corroborated in the thesis that adopting index modulation techniques both in the systems improves the system performance in various aspects.:1 Introduction 1 1.1 Motivation 1 1.2 Overview and Contribution 2 1.3 Outline 9 2 Preliminaries and Fundamentals 13 2.1 Multicarrier Systems 13 2.2 Large-scale Multiple Input Multiple Output Systems 17 2.3 Index Modulation Techniques 19 2.4 Single Cell Multiuser Networks 22 3 Multicarrier Systems with Index Modulation 27 3.1 Orthogonal Frequency Division Multiplexing 28 3.2 Generalized Frequency Division Multiplexing 40 3.3 Summary 52 4 Hybrid Beamforming with Spatial Modulation 55 4.1 Uplink Transmission 56 4.2 Downlink Transmission 74 4.3 Summary 106 5 Conclusion and Outlook 109 5.1 Conclusion 109 5.2 Outlook 111 A Quantization Error Derivations 113 B On the Achievable Rate of Gaussian Mixtures 115 B.1 The Conditional Density Function 115 B.2 Tight Bounds on the Differential Entropy 116 B.3 A Bound on the Achievable Rate 118 C Multiuser MIMO Downlink without Spatial Modulation 121 Bibliography

In this these, in order to enhance the n-channel organic field-effect transistor (OFET) performance, amino functionalized self-assembled monolayers (A-SAMs) which consist of amino groups, a well-known n-type dopant candidate, were introduced from the top of OFET surfaces and on the gate oxide surfaces. To obtain better understanding for optimization of OFET performances we attempted to elucidate the mechanism of surface doping and surface modification by A-SAMs. Both the surface doping and surface modification of the gate oxide approaches have individual pros and cons. One needs to take into account the surface energy properties of SAMs and the resulting OSC film structure and pick the most suitable method to introduce the SAM material to the OFET (either doping or oxide modification) in order to obtain optimized device performances. Our study strongly suggests that both surface doping and surface modification of the gate oxide with A-SAMs could enhance other semiconductor-based electronic device performances.:Abstract v Chapter 1. Introduction 1 Chapter 2. Theoretical Background 7 2.1. Organic Semiconductors (OSCs) 8 2.1.1. Semiconducting properties of organic molecules 8 2.1.2. Charge Transport Mechanism in OSCs 10 2.2. Organic Field-Effect Transistors (OFETs) 18 2.2.1. Operation Principle 18 2.2.2. Device Geometry of OFETs 20 2.2.3. Contacts (metal/semiconductor junction) in OFETs 21 2.2.4. Dielectric material for OFETs 23 2.2.5. Current-Voltage Characteristics of OFETs 25 2.3. Dominant contributors to OFET Performance 32 2.3.1. Molecular structure and Orientation of OSCs 32 2.3.2. Dielectric/OSC Interface 33 2.3.3. OSC/Contact Interface (Contact resistance) 35 2.3.4. Shallow and deep traps 36 2.4. Strategies to improve OFET performance 37 2.4.1. Introducing dopants to OFETs 37 2.4.2. Modification of Gate Oxide Layer with SAMs 44 Chapter 3. Experimental 51 3.1. Device Fabrication 52 3.1.1. Device type I - Substrate/ODTMS/PTCDI-C8/Au 53 3.1.2. Device type II - Substrate/ODTCS/N2200 (PNDI2OD-2T)/Au 53 3.1.3. Device type III - Substrate/SAMs/PTCDI-C8/Au 54 3.2. Surface doping process 56 3.2.1. Surface dopant – Aminosilanes (A-SAMs) 56 3.2.2. Surface doping method 56 3.3. Characterization 59 3.3.1. Material characterization 59 3.3.2. Surface-wetting characterization - Contact angle measurement 61 3.3.3. Micro-structure characterization - Atomic Force Microscopy (AFM) 62 3.3.4. Surface potential characterization – Kelvin Probe Force Microscopy (KPFM) 63 3.3.5. Molecular Structure Characterization - Grazing Incidence Wide Angle X-ray Scattering (GIWAXS) 64 3.3.6. Electrical Characterization - Current-voltage (I-V) measurement 66 Chapter 4. Result and Discussion 69 4.1. Optimization of OFETs based on PTCDI-C8 and N2200 70 4.1.1. PTCDI-C8 OFETs 70 4.1.2. N2200 OFETs 72 4.1.3. Device measurement condition 75 4.2. Investigation of Surface doping mechanism of Aminosilanes 77 4.2.1. Surface doping effect depending on the dopant processing method 77 4.2.2. Surface doping effect for different types of organic semiconductors 80 4.2.3. Surface doping effect for different types of surface dopants 89 4.2.4. Surface doping effect for different OSC grain sizes 92 4.2.5. Surface doping effect for different OSC film thicknesses 103 4.2.6. Molecular structure of the doped films identified by GIWAXS 106 4.2.7. Stability of the surface doped OFETs 107 4.2.8. Summary 111 4.3. Modification of the gate oxide with various self-assembled monolayers 112 4.3.1. The surface property of SAM-treated substrates 112 4.3.2. The relation between the OSC morphology and the field-effect mobility 115 4.3.3. The origin of the threshold voltage shift 126 4.3.4. Memristive effects in PTCDI-C8 devices on ODTMS 133 4.3.5. Summary 137 4.4. Comparison of the surface doping and the modification of the gate dielectric 138 4.4.1. The reliability factor of OFETs 138 4.4.2. The threshold voltages and field-effect mobility of OFETs 141 4.4.3. Density of Interfacial trap sites and SAM induced mobile carriers 143 4.4.4. Summary 144 Chapter 5. Conclusion 145 Bibliography 148 List of Figures 158 List of Tables 166 List of Equations 167 Acknowledgment 168 Erklärung zur Eröffnung des Promotionsverfahrens 169

Micro- and nanorobots (MNRs) are small autonomous devices capable of performing complex tasks and have been demonstrated for a variety of non-invasive biomedical applications, such as tissue engineering, drug delivery or assisted fertilization. However, translating such approaches to an in vivo environment is critical. Current imaging techniques do not allow localization and tracking of single or few micromotors at high spatiotemporal resolution in deep tissue. This thesis addresses some of these limitations, by exploring the use of two optical-based techniques (IR and photoacoustic imaging (PAI)) and a combination of both US and PAI. First, we employ an IR imaging setup to visualize mobile reflective micromotors under scattering phantoms and ex vivo mouse skull tissues, without using any labels. The reflective micromotor reflects more than tenfold the light intensity of a simple particle. However, the achieved penetration depth was ca. 100 μm (when using ex vivo tissues), limiting this technique to superficial biomedical applications. In this regard, PAI plays a role that combines the advantages of US such as penetration depth and real-time imaging with the molecular specificity of optics. For the first time, in this thesis, this method is evaluated for dynamic process monitoring, in particular for tracking single micromotor in real-time below ~1 cm deep phantom and ex vivo tissue. However, the precise function control of MNRs in living organisms, demand the combination of both anatomical and functional imaging methods. Therefore, in the end, we report the use of a hybrid US and PA system for the real-time tracking of magnetically driven micromotors (single and swarms) in phantoms, ex vivo, and in vivo (in mice bladder and uterus), envisioning their application for targeted drug-delivery. This achievement is of great importance and opens the possibilities to employ medical micromotors in a living organism and perform a medical task while being externally controlled and monitored.:ABSTRACT 1 1 INTRODUCTION 5 1.1 Motivation 5 1.2 Background 7 1.2.1 Microrobotics 7 1.2.2 Medical Imaging 9 1.3 Objectives and Structure of Thesis 12 2 FUNDAMENTALS 15 2.1 Optical Imaging 15 2.1.1. Reflection-based Imaging 17 2.1.2. Fluorescence-based Imaging 18 2.1.1 Light-Tissue Interaction 20 2.2 Photoacoustic Imaging 23 2.2.1 Theory 23 2.2.2 Implementation 25 2.3 Ultrasound Imaging 26 2.3.1 Theory 26 2.3.2 Implementation 28 3 MATERIALS AND METHODS 30 3.1 Fabrication of Magnetic Micropropellers 30 3.1.1 3D Laser Lithography of Polymeric Resin 30 3.1.2 Self-assembly of SiO2 Particles 31 3.1.3 Electron Beam Evaporation 32 3.1.4 Surface Functionalization 33 3.2 Fabrication of Phantom Tissue and Microfluidic Channels 34 3.2.1 Fabrication of PDMS-Glycerol Phantom 34 3.2.2 Fabrication of Agarose Phantom 35 3.2.3 Phantom based on Ex vivo Tissues (Chicken Breast and Mice Skull) 36 3.2.4 Microfluidic Channel Platform 37 3.3 Sample Characterization 38 3.3.1 Optical Microscopy 38 3.3.2 Scanning Electron Microscopy 38 3.4 Magnetic Actuation 39 3.4.1 Magnetic Force 39 3.4.2 Magnetic Torque 39 3.5 Ethic Statement for Mice Experiments 41 4 OPTICAL IMAGING OF MICROROBOTS 42 4.1 Concept of Reflective Micromotors 42 4.2 Fabrication of Reflective Micromotors 44 4.3 IR Imaging Actuation Setup 45 4.4 Actuation and Propulsion Performance below Phantom 47 4.5 Actuation and Propulsion Performance below Ex Vivo Skull Tissue 50 4.6 Actuation and Propulsion Performance in Blood 51 5 PHOTOACOUSTIC IMAGING OF MICROROBOTS 55 5.1 Absorbers for Deep Tissue Imaging 55 5.2 Absorber Micromotor Design and Fabrication 56 5.3 Photoacoustic Imaging Setup 58 5.4 Actuation Performance below Phantom Tissue 60 5.5 Actuation Performance below Ex Vivo Tissue 65 6 HYBRID ULTRASOUND AND PHOTOACOUSTIC IMAGING 67 6.1 Hybrid Ultrasound/Photoacoustic System 68 6.2 Fabrication and Characterization of Micromotors 69 6.3 Actuation and Propulsion Performance below Phantom 69 6.4 Actuation and Propulsion Performance below Ex Vivo Tissues 71 6.5 Actuation and Propulsion Performance in Mice 72 6.5.1 Swimming of Micromotors in Bladder 72 6.5.2 Actuation of Micromotors in Uterus 74 6.5.3 3D Multispectral Imaging 76 6.5.4 Towards Targeted Drug Delivery 77 7 SUMMARY AND PERSPECTIVES 80 7.1 Summary 80 7.2 Future Perspectives 83 7.2.1 Contrats Enhancing Labels 84 7.2.2 Novel Imaging Concepts 85 8 REFERENCES 88 9 APPENDIX 105 List of Figures 105 List of Tables 107 Abbreviations 108 List of Publications 109 Acknowledgements 110 Selbstständigkeitserklärung 111 Curriculum Vitae 112