Using industrial robots for machining applications in flexible manufacturing processes lacks a high accuracy. The main reason for the deviation is the flexibility of the gearbox. Secondary Encoders (SE) as an additional, high precision angle sensor offer a huge potential of detecting gearbox deviations. This paper aims to use SE to reduce gearbox compliances with a feed forward, adaptive neural control. The control network is trained with a second network for system identification. The presented algorithm is capable of online application and optimizes the robot accuracy in a nonlinear simulation.

Was in der vorliegenden empirischen Analyse des Einzelfalls mit Blick auf eine umfassende organisationale Transformation als inhärent-emergenter Prozess beschrieben wird, ist gewiss ein Sonderfall: Nach dem Abbruch eines Beratungsprozesses treibt ein System seine Transformation autonom voran, ohne weitere Unterstützung einer Prozessberatung und stellt damit seine Selbstentwicklungsfähigkeit in einem transformativen Prozess der Organisationsentwicklung unter Beweis. Dies ist in der Organisationsentwicklung nicht die Regel und wird sehr wahrscheinlich auch nicht von anderen Organisationen als Modell aufgegriffen, auch nicht von Organisationen desselben Typs (familiengeführte mittelständische Organisationen). Dass ein Eintritt in eine radikale Transformation als autopoietischer Prozess wie hier überhaupt möglich ist, ist den spezifischen Eigenschaften einer Organisation und ihrer zentralen Entscheidungsakteure, besonderen, kontingent geprägten Ereignisketten sowie der aktuellen Konstellation der zweiten Führungsebene zuzuschreiben. Die hier vorgestellte Untersuchung entspricht daher einem „neuen und unbeschriebenen Fall“ (Hering/Jungmann, 2005: 621), einem „per se interessanten Fall“ (ebd.), der sich in keinen Forschungsstand einordnen lässt.

In this paper we present the results of the project “#Datenspende” where during the German election in 2017 more than 4000 people contributed their search results regarding keywords connected to the German election campaign. Analyzing the donated result lists we prove, that the room for personalization of the search results is very small. Thus the opportunity for the effect mentioned in Eli Pariser’s filter bubble theory to occur in this data is also very small, to a degree that it is negligible. We achieved these results by applying various similarity measures to the result lists that were donated. The first approach using the number of common results as a similarity measure showed that the space for personalization is less than two results out of ten on average when searching for persons and at most four regarding the search for parties. Application of other, more specific measures show that the space is indeed smaller, so that the presence of filter bubbles is not evident. Moreover this project is also a proof of concept, as it enables society to permanently monitor a search engine’s degree of personalization for any desired search terms. The general design can also be transferred to intermediaries, if appropriate APIs restrict selective access to contents relevant to the study in order to establish a similar degree of trustworthiness.

Cancer cells often harbor chromosomes in abnormal numbers and with aberrant structure. The consequences of these chromosomal aberrations are difficult to study in cancer, and therefore several model systems have been developed in recent years. We show that human cells with extra chromosome engineered via microcell-mediated chromosome transfer often gain massive chromosomal rearrangements. The rearrangements arose by chromosome shattering and rejoining as well as by replication-dependent mechanisms. We show that the isolated micronuclei lack functional lamin B1 and become prone to envelope rupture, which leads to DNA damage and aberrant replication. The presence of functional lamin B1 partly correlates with micronuclei size, suggesting that the proper assembly of nuclear envelope might be sensitive to membrane curvature. The chromosomal rearrangements in trisomic cells provide growth advantage compared to cells without rearrangements. Our model system enables to study mechanisms of massive chromosomal rearrangements of any chromosome and their consequences in human cells.

Entscheidungen und Entscheidungsprozesse der Legislative der Vereinigten Staaten von Amerika

In recent years, the Federal Republic of Germany has been the most significant destination for asylum-related migration in the European Union. Asylum-related migrants are those who left their country of origin to search for better life in a country that is safe and usually provides better economic opportunities. Most of these migrants sought asylum; however, not all needed international protection. There is a continuum between forced and voluntary migration and the categorization and categories of migrants are very context-dependent. The main research questions in this research report are the following: 1. What kinds of asylum-related migrants (refugees, people with a temporary residence permit, asylum seekers, non-deportable former asylum seekers and undocumented migrants) live in Germany, in particular in Rhineland-Palatinate and Kaiserslautern? 2. What are the everyday lives of asylum-related migrants like in Rhineland-Palatinate and Kaiserslautern? 3. What are the migration wishes and plans of asylum-related migrants in Rhineland-Palatinate and Kaiserslautern? 4. How and for what reasons do asylum-related migrants in Rhineland-Palatinate and Kaiserslautern use the Internet and social media? The research questions are answered based on the empirical material collected during the field research in the spring and summer of 2019. In addition, earlier research and statistics on migrants, asylum seekers and refugees in Germany are utilized. Asylum-related migrants responded according to their own views; the results indicate both their perspectives and our interpretation of them.

The Atacama Desert is one of the driest and probably oldest deserts on Earth where only a few extremophile organisms are able to survive. This study investigated two terricolous and two epiphytic lichens from the fog oasis “Las Lomitas” within the National Park Pan de Azúcar which represents a refugium for a few vascular desert plants and many lichens that can thrive on fog and dew alone. Ecophysiological measurements and climate records were combined with molecular data of the mycobiont, their green algal photobionts and lichenicolous fungi to gain information about the ecology of lichens within the fog oasis. Phylogenetic and morphological investigations led to the identification and description of the new lichen species Acarospora conafii sp. nov. as well as the lichenicolous fungi that accompanied them and revealed the trebouxioid character of all lichen photobionts. Their photosynthetic responses were compared during natural scenarios such as reactivation by high air humidity and in situ fog events to elucidate the activation strategies of this lichen community. Epiphytic lichens showed photosynthetic activity that was rapidly induced by fog and high relative air humidity whereas terricolous lichens were only activated by fog.

Dieser Arbeits- und Forschungsbericht skizziert die Erprobung und beschreibt die Evaluationsergebnisse des wissenschaftlichen Zertifikatskurses „Beraten, Informieren und Schulen in der Pflege“. Der Kurs wurde im Wintersemester 2018/19 an der Hochschule für Wirtschaft und Gesellschaft Ludwigshafen teilerprobt und durch Mitarbeitende des Teilprojektes E-hoch-B – „Pflege und Gesundheit“ begleitet und evaluiert. Ziel war es, die soziodemografischen Merkmale sowie bildungs- und berufsbiografischen Kennzeichen der Teilnehmenden des Zertifikatskurses herauszuarbeiten. Weiterhin sollte festgehalten werden, wie die Teilnehmenden den Zertifikatskurs erlebt haben und welche Handlungsempfehlungen für die Weiterentwicklung und Verstetigung des Kurses abgeleitet werden können. Die Zielgruppe für das evidenzbasierte Bildungsangebot waren berufserfahrene Pflegefachpersonen aus der ambulanten Gesundheitsversorgung. Es sind qualitative Fokusgruppeninterviews durchgeführt worden, die durch Fragebögen flankiert wurden.

Dieser Arbeits- und Forschungsbericht skizziert die Erprobung und beschreibt die Evaluationsergebnisse des wissenschaftlichen Zertifikatskurses „Versorgungsstrategien und psychosoziale Unterstützung für ein Leben mit Demenz zu Hause“. Der Kurs wurde im Wintersemester 2018/19 an der Hochschule für Wirtschaft und Gesellschaft Ludwigshafen erprobt und durch Mitarbeitende des Teilprojektes E-hoch-B – „Pflege und Gesundheit“ begleitet und evaluiert. Ziel war es, die soziodemografischen Merkmale sowie bildungs- und berufsbiografischen Kennzeichen der Teilnehmenden des Zertifikatskurses herauszuarbeiten. Weiterhin sollte festgehalten werden, wie die Teilnehmenden den Zertifikatskurs erleben und welche Handlungsempfehlungen für die Weiterentwicklung und Verstetigung des Kurses abgeleitet werden können. Die Zielgruppe für das evidenzbasierte Bildungsangebot waren berufserfahrene Pflegefachpersonen aus der ambulanten Gesundheitsversorgung. Es sind qualitative Fokusgruppeninterviews durchgeführt worden, die durch Fragebögen flankiert wurden.

Eine große Bandbreite tribologisch belasteter Bauteile kann durch Verwendung einer Oberflächenbeschichtung verbessert werden. Mit Beschichtungswerkstoffen aus Hochleistungspolymeren und funktionellen Füllstoffen lassen sich in tribologischen Systemen niedrige Reib- und Verschleißwerte realisieren. Diese Arbeit zielt auf die Entwicklung von PBI (Polybenzimidazol)-Hochleitungsbeschichtungen für den Einsatz in tribologisch beanspruchten Systemen ab. Die gewonnenen Erkenntnisse ergänzen die bislang unzureichend beschriebenen bzw. erforschten Prozesse zur Herstellung von PBI-basierten Beschichtungen. Als Matrixmaterialien werden PBI sowie PAI (Polyamidimid) als Referenzsystem untersucht. Eine systematische Entwicklung von Lösungsprozessen bildet dabei das erste Prozessfenster zur Herstellung von gelöstem und flüssig verarbeitbarem PBI. Die Entwicklung der Temperprozesse, basierend auf thermischen Analysen mittels dynamischen Differenzkalorimetrie (DSC), stellt in dieser Arbeit ein weiteres Prozessfenster der Beschichtungsherstellung dar. Die daraus resultierenden ungefüllten PBI-Schichten (ohne Füllstoffe) werden systematischen Untersuchungen unterzogen. Thermische Untersuchungen, wie Thermogravimetrie (TGA), die dynamisch-mechanisch-thermische Analyse (DMTA) sowie DSC-Messungen, veranschaulichen die hohe Temperaturbeständigkeit und damit ein breites Temperatureinsatzfenster der PBI-Beschichtungen. Tribologische Untersuchungsergebnisse, insbesondere der Gleitverschleißprüfungen an ungefüllten PBI-Beschichtungen, stellen dessen hervorragende tribologische Leistungsfähigkeit im Vergleich zu den am Markt etablierten PAI-Systemen dar. Begleitend zu tribologischen Analysen werden mechanische, thermische und strukturelle Untersuchungen durchgeführt und miteinander in Korrelation gebracht.Die Herstellung von PBI-PAI-Blends und die anschließenden tribologischen, mechanischen, thermischen und strukturellen Untersuchungen zeigen das Verbesserungspotential eines PAI-Systems durch die Zugabe von PBI-Anteilen. Die Ergebnisse zeigten, dass es möglich ist, ein PAI-System durch die Zugabe von PBI-Anteilen den speziellen Anwendungen entsprechend anzupassen. Die Modifizierung der PBI-Beschichtungen mit Füllstoffen wie Graphit, PTFE usw. sowie deren Bewertung anhand von Gleitverschleißuntersuchungen, bei Variation der Prüfparameter, ermöglichen einen direkten Vergleich mit marktetablierten PAI-Beschichtungscompound und einem kommerziell erhältlichen PBI-Halbzeug. Die ermittelten Messwerte verdeutlichen hierbei das Potential (Verschleißwiderstand, thermische Stabilität) von PBI-Beschichtungen in tribologisch hoch belasteten Systemen. Zur Verbesserung der Abrasivbeständigkeit werden die PBI-Beschichtungen mit harten Titancarbid-Partikeln verstärkt. Eine systematische Untersuchung der Abrasion sowie ein Modell zur Vorhersage des Abrasivverschleißes werden erarbeitet. A wide range of tribologically stressed components can be improved by using a surface coating. Coatings based on high-performance polymers and functional fillers lead to low friction and wear in tribological systems. The objective of this work is the development of high performance coatings based on polybenzimidazole for tribologically stressed systems. The investigations should complete the inadequately described or researched processes for the production of PBI-based coatings. The matrix materials investigated are PBI and PAI (reference system). The systematic development of solution processes represents the first process window for the production of dissolved and liquid processable PBI. The development of annealing processes, based on thermal analyzes (DSC), represents an additional process window of coating production in this work. The resulting pure PBI coatings (without fillers) are subjected to systematic investigations. Thermal characterizations such as Thermogravimetry (TGA), Dynamic Mechanical Thermal Analysis (DMTA) and Differential Scanning Calorimetry (DSC) measurements demonstrate the high temperature resistance and a wide temperature range of PBI coatings. Tribological test results, in particular the sliding wear tests on pure PBI coatings, show their outstanding tribological performance in comparison to the PAI systems established on the market. Accompanying to tribological analyzes, mechanical, thermal and structural investigations are carried out and correlated with each other. The preparation of PBI-PAI blends and the subsequent tribological, mechanical, thermal and structural investigations show the potential for improvement of a PAI system by the addition of PBI fractions. The possibility of adapting a PAI system to the relevant applications by adding PBI fractions to reduce the high material costs of the PBI polymer is presented in this work. The modification of the PBI coatings with fillers such as graphite, PTFE, etc. as well as the subsequent sliding wear tests, with variation of the test parameters (pressure and velocity-variation), allow a direct comparison with the market-established PAI coating compound and a commercially available PBI bulk material. The measured values illustrate the suitability of PBI coatings for tribologically highly loaded systems. To improve the abrasion resistance, the PBI coatings are reinforced with hard titanium carbide particles. Systematic investigations on the abrasion wear as well as a model for the prediction of the abrasive wear are developed.

Private data analytics systems preferably provide required analytic accuracy to analysts and specified privacy to individuals whose data is analyzed. Devising a general system that works for a broad range of datasets and analytic scenarios has proven to be difficult. Despite the advent of differentially private systems with proven formal privacy guarantees, industry still uses inferior ad-hoc mechanisms that provide better analytic accuracy. Differentially private mechanisms often need to add large amounts of noise to statistical results, which impairs their usability. In my thesis I follow two approaches to improve the usability of private data analytics systems in general and differentially private systems in particular. First, I revisit ad-hoc mechanisms and explore the possibilities of systems that do not provide Differential Privacy or only a weak version thereof. Based on an attack analysis I devise a set of new protection mechanisms including Query Based Bookkeeping (QBB). In contrast to previous systems QBB only requires the history of analysts’ queries in order to provide privacy protection. In particular, QBB does not require knowledge about the protected individuals’ data. In my second approach I use the insights gained with QBB to propose UniTraX, the first differentially private analytics system that allows to analyze part of a protected dataset without affecting the other parts and without giving up on accuracy. I show UniTraX’s usability by way of multiple case studies on real-world datasets across different domains. UniTraX allows more queries than previous differentially private data analytics systems at moderate runtime overheads.

In cyanobacteria and plants, VIPP1 plays crucial roles in the biogenesis and repair of thylakoid membrane protein complexes and in coping with chloroplast membrane stress. In chloroplasts, VIPP1 localizes in distinct patterns at or close to envelope and thylakoid membranes. In vitro, VIPP1 forms higher-order oligomers of >1 MDa that organize into rings and rods. However, it remains unknown how VIPP1 oligomerization is related to function. Using time-resolved fluorescence anisotropy and sucrose density gradient centrifugation, we show here that Chlamydomonas reinhardtii VIPP1 binds strongly to liposomal membranes containing phosphatidylinositol-4-phosphate (PI4P). Cryo-electron tomography reveals that VIPP1 oligomerizes into rods that can engulf liposomal membranes containing PI4P. These findings place VIPP1 into a group of membrane-shaping proteins including epsin and BAR domain proteins. Moreover, they point to a potential role of phosphatidylinositols in directing the shaping of chloroplast membranes.

Anisotropy of tracer-coupled networks is a hallmark in many brain regions. In the past, the topography of these networks was analyzed using various approaches, which focused on different aspects, e.g., position, tracer signal, or direction of coupled cells. Here, we developed a vector-based method to analyze the extent and preferential direction of tracer spreading. As a model region, we chose the lateral superior olive—a nucleus that exhibits specialized network topography. In acute slices, sulforhodamine 101-positive astrocytes were patch-clamped and dialyzed with the GJ-permeable tracer neurobiotin, which was subsequently labeled with avidin alexa fluor 488. A predetermined threshold was used to differentiate between tracer-coupled and tracer-uncoupled cells. Tracer extent was calculated from the vector means of tracer-coupled cells in four 90° sectors. We then computed the preferential direction using a rotating coordinate system and post hoc fitting of these results with a sinusoidal function. The new method allows for an objective analysis of tracer spreading that provides information about shape and orientation of GJ networks. We expect this approach to become a vital tool for the analysis of coupling anisotropy in many brain regions

Passive graduated filters with fixed absorption profile are currently used in image recording to avoid overexposure. However, a whole set of filters with prescribed gradients is required to cope with changing illumination conditions. Furthermore, they demand mechanical adjustment during operation. To overcome these deficiencies we present a microfabricated active electrochromic graduated filter which combines multiple functionalities: The overall absorbance, the position of medium transmission as well as the magnitude of its gradient can be tuned continuously by electrical means. Live image control is possible using low operation voltages in the range of ±2 V to reach a high change in optical density ΔOD of 1.01 (400 nm to 780 nm) with a coloration and bleaching time 1.3 s and 0.2 s, respectively. Owing to their low volume and power consumption they are suitable for widespread applications like in smartphones, surveillance cameras or microscopes.

Verkündungsblatt der TU Kaiserslautern Nr. 6/17.12.2019

We present a study of the dynamic magnetic properties of TiN-buffered epitaxial thin films of the Heusler alloy Fe1.5CoGe. Thickness series annealed at different temperatures are prepared and the magnetic damping is measured, a lowest value of α = 2.18 × 10−3 is obtained. The perpendicular magnetic anisotropy properties in Fe1.5CoGe/MgO are also characterized. The evolution of the interfacial perpendicular anisotropy constant K⊥S with the annealing temperature is shown and compared with the widely used CoFeB/MgO interface. A large volume contribution to the perpendicular anisotropy of (4.3 ± 0.5) × 105 J/m3 is also found, in contrast with vanishing bulk contribution in common Co- and Fe-based Heusler alloys.

Die räumliche Planung begegnet häufig Herausforderungen, zu deren Bewältigung nicht auf existierendes Wissen zurückgegriffen werden kann. Um neuartiges Wissen zu erzielen, werden insbesondere Modellvorhaben – kleinmaßstäbliche, befristete reale Feldexperimente – als Instrument eingesetzt. Diese zielen darauf ab, wiederverwendbares Wissen reproduzierbar zu erzeugen. Im Rahmen eines Modellvorhabens werden in verschiedenen Modellräumen vielfältige innovative Projekte initiiert, über einen festen Zeitraum umgesetzt sowie bewertet. Akademische oder private Institutionen begleiten Modellvorhaben wissenschaftlich, um allgemeingültige und übertragbare Erkenntnisse zu identifizieren. Die Ergebnisse dieser umfassenden Evaluation werden in einem Abschlussbericht dokumentiert. Erfahrungen zeigen allerdings, dass dies zur Verteilung der Ergebnisse nicht ausreicht, um die Nutzung und Wiederverwendung der in Modellvorhaben generierten Erkenntnisse sicherzustellen. Dies liegt insbesondere daran, dass die Abschlussberichte zu wenig anwendungsorientiert und zu umfangreich sind. So ist der Vergleich zwischen vorhandenen Berichten und einem laufenden Modellvorhaben mit einem zu hohen Aufwand verbunden, wodurch sich ein unausgeglichenes Aufwand-Ertrag-Verhältnis ergibt. Somit wird das Lernen aus Modellvorhaben erschwert. Um eine effektive und effiziente Dissemination und Verstetigung sowie Wiederverwendbarkeit von Wissen generiert in Modellvorhaben zu erzielen, wurde im Rahmen der vorliegenden Forschungsarbeit ein Modell entwickelt. In einem ersten Schritt wurde für die Analyse von Modellvorhaben eine allgemeingültige Struktur geschaffen, die mit dem generellen Ablauf eines Projekts im Rahmen des Projektmanagements vergleichbar ist. Diese Struktur reduziert den Aufwand Erkenntnisse und Wissen jeweils für die folgenden hier definierten Phasen zu nutzen: Identifikation einer neuen Herausforderung; Projektaufruf; Bewerbungen der möglichen Teilnehmer; Bewertungen der Bewerbungen durch den Initiator; Durchführung; Auswertung; Dissemination, Transfer und Verstetigung. Im nächsten Schritt wurde in die einzelnen Phasen eines Modellvorhabens ein Wissensmanagementprozess – die Bausteine Wissensziele, -identifikation, -erwerb, - entwicklung, -bewertung, -bewahrung, -(ver)teilung und -nutzung – integriert, um die gemeinsame Nutzungseinheit vom umfassenden Abschlussbericht auf kleinere, in sich abgeschlossene Informationseinheiten zu reduzieren. Auf diese Weise wird der Aufwand für die Identifikation, den Erwerb und die Nutzung von Wissen verringert. Am Ende jeder Phase wird eine Bewertung durchgeführt sowie das erzielte Wissen effizient geteilt. Dafür ist eine systematische Interaktion zwischen Akteuren von Modellvorhaben und eine zentrale Sammlung des Wissens notwendig. Ein wesentliches Ergebnis dieser Arbeit ist die Entwicklung einer neuartigen Austauschinfrastruktur, die das generierte Wissen einerseits bewahrt und andererseits systematisch verteilt. Dadurch kann bereits im Verlauf eines Modellvorhabens gewonnenes Wissen ausgetauscht und wiederverwendet werden, sodass die Phase der Dissemination, Transfer und Verstetigung in den Prozess verschoben wird. Die Infrastruktur soll frei zugänglich sein und nutzerfreundlich gestaltet werden. Durch das entwickelte Modell wird eine effektive und effiziente Wiederverwendung von Wissen generiert in Modellvorhaben ermöglicht sowie eine belastbare Grundlage für neue Projekte in der räumlichen Planung geschaffen.

Using molecular dynamics simulations, the adsorption and diffusion of cisplatin drug molecules in nanopores is investigated for several inorganic materials. Three different materials are studied with widely-varying properties: metallic gold, covalent silicon, and silica. We found a strong influence of both the van der Waals and the electrostatic interaction on the adsorption behavior on the pore walls, which in turn influence the diffusion coefficients. While van der Waals forces generally lead to a reduction of the diffusion coefficient, the fluctuations in the electrostatic energy induced by orientation changes of the cisplatin molecule were found to help desorb the molecule from the wall.

Intensity regulation during whole-body electromyostimulation (WB-EMS) training is mostly controlled by subjective scales such as CR-10 Borg scale. To determine objective training intensities derived from a maximum as it is used in conventional strength training using the one-repetition-maximum (1-RM), a comparable maximum in WB-EMS is necessary. Therefore, the aim of this study was to examine, if there is an individual maximum intensity tolerance plateau after multiple consecutive EMS application sessions. A total of 52 subjects (24.1 ± 3.2 years; 76.8 ± 11.1 kg; 1.77 ± 0.09 m) participated in the longitudinal, observational study (38 males, 14 females). Each participant carried out four consecutive maximal EMS applications (T1–T4) separated by 1 week. All muscle groups were stimulated successively until their individual maximum and combined to a whole-body stimulation index to carry out a possible statement for the development of the maximum intensity tolerance of the whole body. There was a significant main effect between the measurement times for all participants (p < 0.001; ????2 = 0.39) as well as gender specific for males (p = 0.001; ????2 = 0.18) and females (p < 0.001; ????2 = 0.57). There were no interaction effects of gender × measurement time (p = 0.394). The maximum intensity tolerance increased significantly from T1 to T2 (p = 0.001) and T2 to T3 (p < 0.001). There was no significant difference between T3 and T4 (p = 1.0). These results indicate that there is an adjustment of the individual maximum intensity tolerance to a WB-EMS training after three consecutive tests. Therefore, there is a need of several habituation units comparable to the identification of the individual 1-RM in conventional strength training. Further research should focus on an objective intensity-specific regulation of the WB-EMS based on the individual maximum intensity tolerance to characterize different training areas and therefore generate specific adaptations to a WB-EMS training compared to conventional strength training methods.

Phase-gradient metasurfaces can be designed to manipulate electromagnetic waves according to the generalized Snell’s law. Here, we show that a phased parallel-plate waveguide array (PPWA) can be devised to act in the same manner as a phase-gradient metasurface. We derive an analytic model that describes the wave propagation in the PPWA and calculate both the angle and amplitude distribution of the diffracted waves. The analytic model provides an intuitive understanding of the diffraction from the PPWA. We verify the (semi-)analytically calculated angle and amplitude distribution of the diffracted waves by numerical 3-D simulations and experimental measurements in a microwave goniometer.

In this dissertation we apply financial mathematical modelling to electricity markets. Electricity is different from any other underlying of financial contracts: it is not storable. This means that electrical energy in one time point cannot be transferred to another. As a consequence, power contracts with disjoint delivery time spans basically have a different underlying. The main idea throughout this thesis is exactly this two-dimensionality of time: every electricity contract is not only characterized by its trading time but also by its delivery time. The basis of this dissertation are four scientific papers corresponding to the Chapters 3 to 6, two of which have already been published in peer-reviewed journals. Throughout this thesis two model classes play a significant role: factor models and structural models. All ideas are applied to or supported by these two model classes. All empirical studies in this dissertation are conducted on electricity price data from the German market and Chapter 4 in particular studies an intraday derivative unique to the German market. Therefore, electricity market design is introduced by the example of Germany in Chapter 1. Subsequently, Chapter 2 introduces the general mathematical theory necessary for modelling electricity prices, such as Lévy processes and the Esscher transform. This chapter is the mathematical basis of the Chapters 3 to 6. Chapter 3 studies factor models applied to the German day-ahead spot prices. We introduce a qualitative measure for seasonality functions based on three requirements. Furthermore, we introduce a relation of factor models to ARMA processes, which induces a new method to estimate the mean reversion speed. Chapter 4 conducts a theoretical and empirical study of a pricing method for a new electricity derivative: the German intraday cap and floor futures. We introduce the general theory of derivative pricing and propose a method based on the Hull-White model of interest rate modelling, which is a one-factor model. We include week futures prices to generate a price forward curve (PFC), which is then used instead of a fixed deterministic seasonality function. The idea that we can combine all market prices, and in particular futures prices, to improve the model quality also plays the major role in Chapter 5 and Chapter 6. In Chapter 5 we develop a Heath-Jarrow-Morton (HJM) framework that models intraday, day-ahead, and futures prices. This approach is based on two stochastic processes motivated by economic interpretations and separates the stochastic dynamics in trading and delivery time. Furthermore, this framework allows for the use of classical day-ahead spot price models such as the ones of Schwartz and Smith (2000), Lucia and Schwartz (2002) and includes many model classes such as structural models and factor models. Chapter 6 unifies the classical theory of storage and the concept of a risk premium through the introduction of an unobservable intrinsic electricity price. Since all tradable electricity contracts are derivatives of this actual intrinsic price, their prices should all be derived as conditional expectation under the risk-neutral measure. Through the intrinsic electricity price we develop a framework, which also includes many existing modelling approaches, such as the HJM framework of Chapter 5.

Radar cross section reducing (RCSR) metasurfaces or coding metasurfaces were primarily designed for normally incident radiation in the past. It is evident that the performance of coding metasurfaces for RCSR can be significantly improved by additional backscattering reduction of obliquely incident radiation, which requires a valid analytic conception tool. Here, we derive an analytic current density distribution model for the calculation of the backscatter far-field of obliquely incident radiation on a coding metasurface for RCSR. For demonstration, we devise and fabricate a metasurface for a working frequency of 10.66GHz and obtain good agreement between the measured, simulated, and analytically calculated backscatter far-fields. The metasurface significantly reduces backscattering for incidence angles between −40∘ and 40∘ in a spectral working range of approximately 1GHz.

3D joint kinematics can provide important information about the quality of movements. Optical motion capture systems (OMC) are considered the gold standard in motion analysis. However, in recent years, inertial measurement units (IMU) have become a promising alternative. The aim of this study was to validate IMU-based 3D joint kinematics of the lower extremities during different movements. Twenty-eight healthy subjects participated in this study. They performed bilateral squats (SQ), single-leg squats (SLS) and countermovement jumps (CMJ). The IMU kinematics was calculated using a recently-described sensor-fusion algorithm. A marker based OMC system served as a reference. Only the technical error based on algorithm performance was considered, incorporating OMC data for the calibration, initialization, and a biomechanical model. To evaluate the validity of IMU-based 3D joint kinematics, root mean squared error (RMSE), range of motion error (ROME), Bland-Altman (BA) analysis as well as the coefficient of multiple correlation (CMC) were calculated. The evaluation was twofold. First, the IMU data was compared to OMC data based on marker clusters; and, second based on skin markers attached to anatomical landmarks. The first evaluation revealed means for RMSE and ROME for all joints and tasks below 3°. The more dynamic task, CMJ, revealed error measures approximately 1° higher than the remaining tasks. Mean CMC values ranged from 0.77 to 1 over all joint angles and all tasks. The second evaluation showed an increase in the RMSE of 2.28°– 2.58° on average for all joints and tasks. Hip flexion revealed the highest average RMSE in all tasks (4.87°– 8.27°). The present study revealed a valid IMU-based approach for the measurement of 3D joint kinematics in functional movements of varying demands. The high validity of the results encourages further development and the extension of the present approach into clinical settings.

Modern applications in the realms of wireless communication and mobile broadband Internet increase the demand for compact antennas with well defined directivity. Here, we present an approach for the design and implementation of hybrid antennas consisting of a classic feeding antenna that is near-field-coupled to a subwavelength resonator. In such a combined structure, the composite antenna always radiates at the resonance frequency of the subwavelength oscillator as well as at the resonance frequency of the feeding antenna. While the classic antenna serves as impedance-matched feeding element, the subwavelength resonator induces an additional resonance to the composite antenna. In general, these near-field coupled structures are known for decades and are lately published as near-field resonant parasitic antennas. We describe an antenna design consisting of a high-frequency electric dipole antenna at fd=25 GHz that couples to a low-frequency subwavelength split-ring resonator, which emits electromagnetic waves at fSRR=10.41 GHz. The radiating part of the antenna has a size of approximately 3.2mm×8mm×1mm and thus is electrically small at this frequency with a product k⋅a=0.5 . The input return loss of the antenna was moderate at −18 dB and it radiated at a spectral bandwidth of 120 MHz. The measured main lobe of the antenna was observed at 60∘ with a −3 dB angular width of 65∘ in the E-plane and at 130∘ with a −3 dB angular width of 145∘ in the H-plane

The fifth-generation mobile telecommunication network is expected to support multi-access edge computing (MEC), which intends to distribute computation tasks and services from the central cloud to the edge clouds. Toward ultra-responsive, ultra-reliable, and ultra-low-latency MEC services, the current mobile network security architecture should enable a more decentralized approach for authentication and authorization processes. This paper proposes a novel decentralized authentication architecture that supports flexible and low-cost local authentication with the awareness of context information of network elements such as user equipment and virtual network functions. Based on a Markov model for backhaul link quality as well as a random walk mobility model with mixed mobility classes and traffic scenarios, numerical simulations have demonstrated that the proposed approach is able to achieve a flexible balance between the network operating cost and the MEC reliability.