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Open science requires open-source tools that produce verifiable results. Nevertheless, a universal opensource tool in railway engineering is still missing. This paper presents an open-source tool for running time estimation to promote a change toward more open tools. Besides the tool’s implementation, the need for simple data formats and data sources is discussed. The tool was tested against a commercial tool and revealed variations in the computation. Nonetheless, the tool can already deliver valuable results for simple investigations.

A pressure resistant and optically accessible deterministic lateral displacement (DLD) device was designed and microfabricated from silicon and glass for high-throughput fractionation of particles between 3.0 and 7.0 µm comprising array segments of varying tilt angles with a post size of 5 µm. The design was supported by computational fluid dynamic (CFD) simulations using OpenFOAM software. Simulations indicated a change in the critical particle diameter for fractionation at higher Reynolds numbers. This was experimentally confirmed by microparticle image velocimetry (µPIV) in the DLD device with tracer particles of 0.86 µm. At Reynolds numbers above 8 an asymmetric flow field pattern between posts could be observed. Furthermore, the new DLD device allowed successful fractionation of 2 µm and 5 µm fluorescent polystyrene particles at Re = 0.5−25.

The dependency of the friction factor on the flow direction was investigated experimentally in a milled scale model of an unlined rock blasted tunnel under pressurized flow conditions by reversing the flow direction. The experimental data were used to highlight the significance of anisotropic roughness structures and variations in the cross-sectional area on the flow resistance. It is hypothesized that local sudden expansions of the cross-sectional area, which are followed by gradual contractions, contribute significantly to the directional dependency of the friction factor due to potential flow separation. For the reversed case, i.e. when sudden large-scale contractions were followed by gradual expansions, 15% lower friction factors were observed. The results were also used to highlight the scale dependency of these topographical features, the dependency of the friction factor from the tunnel driving direction, and to show the need for the development of methods that can be used to parameterize the directional dependency of hydraulic roughness and friction factors.

Durch die immer stärker werdenden Forderungen nach effizienten und emissionsarmen Antriebslösungen, schreitet die Elektrifizierung des Verkehrssektors voran. Zur Steigerung der Reichweite eines Elektrofahrzeugs wird der Wirkungsgrad des gesamten Antriebsstranges stetig optimiert. Da gerade bei großen Zwischenkreisspannungen die Verwendung eines Multilevel-Wechselrichters zu geringeren Schaltverlusten und Rippelströmen führt, werden diese vermehrt eingesetzt. Diesen Vorteilen steht die Notwendigkeit einer Balancierung der Spannungslevel als Nachteil gegenüber. Das Gesamtsystem aus Antriebsmaschine und Multilevel-Wechselrichter weist aufgrund des diskret umschaltenden Wechselrichters sowohl eine kontinuierliche als auch eine diskrete Systemdynamik auf. Da das diskrete Verhalten einen signifikanten Einfluss auf die in den Signalen enthaltenen Rauschanteile hat, ist es für eine detaillierte Systemanalyse ratsam das diskrete Verhalten möglichst genau in der Modellierung abzubilden. Die bereits existierenden Modulationsverfahren für Multilevel-Wechselrichter betrachten nur bedingt das diskrete Verhalten des zu regelnden Systems. Einer Beschreibung des Systems durch Methoden der Regelungstechnik geht meist die Vernachlässigung oder Näherung des diskreten Verhaltens durch entsprechende Modelle voraus. Eine Möglichkeit die gesamte Systemdynamik zu berücksichtigen, ist die Theorie der schaltenden Systeme. Der Fokus der oben genannten Arbeit liegt auf der Anwendung dieser Theorie zur Modellierung des Systems aus Antriebsmaschine und Multilevel-Wechselrichter. Basierend auf dem so modellierten System wird ein Hysterese-basiertes Stromregelverfahren entwickelt, welches neben dem Erreichen und Folgen einer Stromreferenztrajektorie die Balancierung der Spannungslevel des Multilevel-Wechselrichters gewährleistet. Neben diesen Hauptforderungen werden zudem die Schaltfrequenz nach oben und die Mindesteinschaltdauer der schaltenden Bauelemente nach unten begrenzt. Das vorgestellte Verfahren wird innerhalb einer Simulationsumgebung durch Vorgabe einer Stromreferenztrajektorie und eines Drehzahlprofils hinsichtlich Regelgüte, Stromrippel und Schaltfrequenzverhalten evaluiert. Aufgrund der weiten Verbreitung der beiden Bauformen wird als Antriebsmaschine eine permanenterregte Synchronmaschine und als Multilevel-Wechselrichter ein neutral point clamped t type 3 level converter verwendet., Due to the increasing demand for efficient and low-emission drive solutions, the electrification of the transport sector is advancing. To increase the range of an electric vehicle, the efficiency of the entire drive train is constantly being optimized. Since the application of a multilevel converter leads to lower switching losses and ripple currents, especially with large DC link voltages, they are increasingly implemented. These advantages are countered by the necessity of balancing the voltage levels as a disadvantage. The overall system of drive machine and multilevel converter exhibits both continuous and discrete system dynamics due to the discrete switching converter. Since the discrete behavior has a significant influence on the noise components contained in the signals, it is advisable for a detailed system analysis to represent the discrete behavior as accurately as possible in the modeling. The already existing modulation methods for multilevel converters only consider the discrete behavior of the controlled system to a limited extent. A description of the system by methods of control engineering is usually preceded by the neglect or approximation of the discrete behavior by corresponding models. One possibility to consider the whole system dynamics is the theory of switched systems. The focus of the above work is on applying this theory to model the system of drive machine and multilevel converter. Based on the system modeled in this way, a hysteresis-based current control method is developed which, in addition to achieving and following a current reference trajectory, ensures the balancing of the voltage levels of the multilevel converter. In addition to these main requirements, the switching frequency is also upper bounded and the minimum duty cycle of the switching devices is lower bounded. The presented method is evaluated within a simulation environment by prescribing a current reference trajectory and a speed profile with respect to control performance, current ripple and switching frequency behavior. Due to the widespread use of the two designs, a permanent magnet synchronous machine is used as the drive machine and a neutral point clamped t type 3 level converter is used as the multilevel converter.

Due to their ability to self-assemble into complex structures, block copolymers are of great interest for use in a wide range of future applications, such as self-healing materials. Therefore, it is important to understand the mechanisms of their structure formation. In particular, the process engineering of the formation and transition of the polymer structures is required for ensuring reproducibility and scalability, but this has received little attention in the literature. In this article, the influence of the addition rate of the selective solvent on the homogeneity of self-assembled vesicles of polystyrene-block-polyacrylic acid is demonstrated, as well as the influence of the reaction time and the mixing intensity on the morphology of the polymer structures. For example, it was demonstrated that the higher the mixing intensity, the faster the transition from micelle to vesicle. The experimental results are further supported by CFD simulations, which visually and graphically show an increase in shear rate and narrower shear rate distributions at higher stirring rates. Furthermore, it was demonstrated that the vesicle size is not only kinetically determined, since flow forces above a critical size lead to the deformation and fission of the vesicles.

By taking into account the turbine type, terrain, wind climate and layout, the effects of wind turbine wakes and other losses, engineering models enable the rapid estimation of energy yields for prospective and existing wind farms. We extend the capability of engineering models, such as the existing deep-array wake model, to account for additional losses that may arise due to the presence of clusters of wind farms, such as the global blockage effect and large-scale wake effects, which become more significant with increasing thermal stratification. The extended strategies include an enhanced wind-farm-roughness approach which assumes an infinite wind farm, and recent developments account for the upstream flow blockage. To test the plausibility of such models in capturing the additional blockage and wake losses in real wind farm clusters, the extended strategies are compared with large-eddy simulations of the flow through a cluster of three wind farms located in the German sector of the North Sea, as well as real measurements of wind power within these wind farms. Large-eddy simulations and wind farm measurements together suggest that the extensions of the Openwind model help capture the different flow features arising from flow blockage and cluster effects, but further model refinement is needed to account for higher-order effects, such as the effect of the boundary-layer height, which is not currently included in standard engineering models.

Lead-free piezoelectric materials are essential for our healthy future but offer lower performance than lead-based materials. Different material combinations are explored to improve the performance of lead-free materials. By filling the UV light curable photopolymer resin with 30 vol.% lead-free piezoelectric ceramics and with up to 0.4 wt.% conductive nanofillers, thin and flexible piezoelectric 0-0-3 composites are formed. Two particle sizes of Potassium Sodium Niobate (KNN) and Barium Titanate (BTO) ceramics were used with four conductive nanofillers: Graphene Nanoplatelets (GNPs), Multi-Walled Carbon Nanotubes (MWCNTs), and two types of Graphene Oxide (GO). Resulting high viscosity suspensions are tape-cast in a mold as thin layers and subsequently exposing them to UV light, piezoelectric composite sensors are formed in 80 s. Even low nanofiller concentrations increase relative permittivities, however, they strongly reduce curing depth and increase undesirable dielectric losses. Non-homogeneous dispersion of nanofillers is observed. In total, 36 different compositions were mixed and characterized. Only six selected material compositions were investigated further by measuring mechanical, dielectric, and piezoelectric properties. Results show KNN composite performance as piezoelectric sensors is almost six times higher than BTO composite performance.

In recent years, many simulation tools emerged to model the communication of connected vehicles. Thereby, the focus was put on channel modelling, applications or protocols while the localisation due to satellite navigation systems was treated as perfect. The effect of inaccurate positioning, however, was neglected so far. This paper presents an approach to extend an existing simulation framework for radio networks to estimate the localisation accuracy by navigation systems like GPS, GLONASS or Galileo. Therefore the error due multipath components is calculated by ray optical path loss predictions (ray tracing) considering 3D building data together with a well-established model for the ionospheric error.

The change in the orbital movement that occurs with water waves (from approximately circular in deep water to increasingly elliptical with decreasing water depth) deviates from the conservative view of the shoaling process such that it is accompanied a priori by the phenomenon of reflection. Thereby the long principal axes of the ellipse grow at the expense of the short principal axes. For deep water conditions (d/L ≥ 0.5), according to the theory ERR used by the author [1], for example, the circular movement on that of the diameter D1 (= wave height H) on the water surface is superimposed on that of a smaller circular diameter D2. The familiar relationship applies D2 = D1 ·e-2πd/L with d/L as the ratio of the water depth d to the wavelength L. The phenomenon of exponentially reduced reflection (ERR) [2] is taken into account by the fact that the water depth d < L/2 is assumed for the reflection and accordingly a reversal of the direction of rotation of the orbital movement occurs. At a given water depth (mirror depth) d2 < L/2, the circular orbital movement of the diameter D1 on the water surface would have to be superimposed by the orbital movement of diameter D2, which results from the above exponential law at twice the distance 2d2 from the water surface. The theory at hand is checked on the one hand using the example of the calculation of the kinematics for water waves with regard to the dimensioning of offshore structures [3] and on the other hand the example of the earth's elliptical orbit around the sun is placed alongside the results of the well-known epicyclic theory.

In the last decades, the multi-scale approach has gained wide attention for studying and understanding the mechanisms affecting the performance of asphalt mixtures. According to such approach, the asphalt mixture could be seen as an assemblage of components of different length scales, each with its own mechanical properties, and thanks to the investigation on these lower scales a scale-wise insight can be gained and used to capture phenomena not considered in continuum approaches. This Thesis is focused on the interrelation between the Fine Aggregate Matrix (FAM) the asphalt mixtures. Fine aggregates, filler, binder and air voids compose the FAM, which represents the intermediate scale between mastic and asphalt mixture. This phase has a critical role in the overall performance evaluation of asphalt mixture and the simplicity, efficiency and the lower costs/times required to study the FAM make it a very attractive specification-type approach. However, despite the growing interest on FAM testing, there are some concerns about proper FAM mix design. Moreover, there are many lacks in predicting the performances of asphalt mixtures from the FAM phase. The primary objective of this Thesis was the identification of a design method for FAM, which allows recreating the FAM phase, as it exists within the asphalt mixture. The selected design method has shown promising results and seems quite accurate in reproducing the FAM within the asphalt mixture. The second issue which is pursued in this Thesis, is a multi-scale approach based on the rheological 2S2P1D model, allowing to interrelate the four material scales (from binder to asphalt mixture). Firstly, it was verified that the 2S2P1D model remains valid for FAM in the Linear ViscoElastic (LVE) range and that it could adequately fit experimental data of FAM. Then, it was possible to relate the different phases thanks to the definition of interrelationships between one model parameter. The interrelation between the asphalt mixture and the corresponding FAM could be used to predict the rheological properties of the asphalt mixtures starting from FAM tests. This methodology allows making reliable forecasts of the LVE behaviour of the asphalt mixtures, as demonstrated by the results of validation tests. Future developments will investigate other volumetric compositions of mixes, to study the influence of microstructural and volumetric characteristics on the model parameters., Der sogenannte "Multi-Skala" -Ansatz wird verwendet, um die Mechanismen zu untersuchen und verstehen, die die Leistung von bituminösen Konglomeraten beeinflussen. Nach diesem Ansatz können die Gemische als Baugruppen von Bauteilen (Teilphasen) angesehen werden, und dank der Untersuchung ihrer Leistung in kleinem Maßstab, ist es möglich Leistungsindizes der bituminösen Gemische und Performance-Informationen vor Ort zu erhalten. Diese Arbeit konzentriert sich insbesondere auf das Verständnis der Wechselbeziehung zwischen der sogenannten FAM-Subphase und die bituminösen Konglomeraten. Diese Phase zwischen Kitten und Gemischen spielt eine grundlegende Rolle bei der Gesamtleistungsbewertung von bituminösen Gemischen, und die Einfachheit, Effizienz und geringeren Kosten und Zeiten von FAM-Tests machen sie noch interessanter. Trotzdem bestehen weiterhin Vorbehalte gegen ihre Verwendung zur Charakterisierung und Klassifizierung von Gemischen, da keine Übereinstimmung über deren korrektes Mischungsdesign und über die Herstellung repräsentativer Proben der Gemische besteht. Es gibt auch Mängel bei der Modellierung der Leistung von Gemischen aus Labortests an FAMs. Das erste Ziel dieser Arbeit war es, eine Methode für das korrekte Design des FAM-Mix-Designs zu identifizieren. Die Genauigkeit der ausgewählten Methode wurde dann empirisch verifiziert, was zu einem ausreichend hohen Ergebnis führte. Anschließend wurde ein mehrskaliger Ansatz basierend auf dem rheologischen 2S2P1D-Modell verwendet, um die vier analysierten Phasen (Bitumen, Mastix, FAM und bituminöses Konglomerat) miteinander in Beziehung zu setzen. Nachdem wir überprüft hatten, ob das Modell für die Modellierung der experimentellen FAM-Daten gültig war, suchten wir nach einer Wechselbeziehung eines Modellparameters (charakteristische Zeit) zwischen den verschiedenen Phasen. Insbesondere kann die Bestimmung der Beziehung zwischen der charakteristischen Zeit der Gemische und der des entsprechenden FAM verwendet werden, um das Verhalten der Gemische ausgehend von den experimentellen Daten der FAMs vorherzusagen. Diese Forschung stellt eine wichtige Referenz für zukünftige Studien dar und liefert Richtlinien für das Design des Mix-Designs der FAMs und für die Realisierung der Proben. Darüber hinaus bietet es einige interessante Einblicke in die Untersuchung des Einflusses der volumetrischen Zusammensetzung und der Mikrostruktur des Gemisches auf die Parameter des 2S2P1D-Modells.

Nowadays, a complex transportation network has been a symbol of urbanization development. Convenient transportation enriches people’s life. However, on one hand, traffic noise and vibrations from the transportation network are around everyone in the city, which affect the living condition of urban residents and could result in sleeping disorders. Besides the effects on humans, vibrations affect the integrity of historical buildings and can undermine the stability of sensitive buildings as hospitals, scientific research labs, and high-tech industries. On the other hand, the indirect impact of the more convenient transportation network is the recycling problem of end-of-life tires from increasing numbers of vehicles. To solve the above-mentioned issues, the present study aims to refine and optimize a new noise and vibration absorbing system for road pavements, and to meet the requirement of sustainability by the use of crumb rubber from end-of-life tires (ELTs). This noise and vibration absorbing system is composed of a gap graded asphalt surface layer containing a certain amount of crumb rubber and a lower vibration-absorbing layer with higher damping property. The main objectivities of this study are to study the noise reduction mechanism of the surface layer, to design and evaluate the asphalt mixtures for the damping layer based on the mechanical and damping properties, and to optimize the pavement structure based on the functional and mechanical characteristics., Ein komplexes Verkehrsnetz ist heute ein Symbol für die Urbanisierungsentwicklung. Bequemer Transport bereichert das Leben der Menschen. Einerseits sind Verkehrslärm und Vibrationen des Verkehrsnetzes in der Stadt allgegenwärtig, was sich auf die Lebensbedingungen der Stadtbewohner auswirkt und zu Schlafstörungen führen kann. Neben den Auswirkungen auf den Menschen beeinträchtigen Vibrationen die Integrität historischer Gebäude und können die Stabilität empfindlicher Gebäude wie Krankenhäuser, wissenschaftliche Forschungslabors und High-Tech-Industrien beeinträchtigen. Andererseits ist die indirekte Auswirkung des bequemeren Transportnetzes das Recyclingproblem von Altreifen aus einer zunehmenden Anzahl von Fahrzeugen. Um die oben genannten Probleme zu lösen, zielt die vorliegende Studie darauf ab, ein neues Geräusch- und Vibrationsabsorptionssystem für Straßenbeläge zu verfeinern und zu optimieren und die Anforderungen an Nachhaltigkeit durch die Verwendung von Krümelgummi aus Altreifen (ELTs) zu erfüllen. . Dieses Geräusch- und Vibrationsabsorptionssystem besteht aus einer spaltgradierten Asphaltoberflächenschicht, die eine bestimmte Menge Krümelkautschuk enthält, und einer niedrigeren vibrationsabsorbierenden Schicht mit höheren Dämpfungseigenschaften. Die Hauptziele dieser Studie sind die Untersuchung des Geräuschreduzierungsmechanismus der Oberflächenschicht, die Auslegung und Bewertung der Asphaltmischungen für die Dämpfungsschicht auf der Grundlage der mechanischen und Dämpfungseigenschaften sowie die Optimierung der Fahrbahnstruktur auf der Grundlage der funktionellen und mechanischen Eigenschaften.

Land subsidence, together with landslides and floods, represents one of the main natural hazards that affect several countries all over the world, potentially causing significant damages to buildings and infrastructures. In particular, Firenze-Prato-Pistoia basin has a long experience of ground deformation related to groundwater withdrawal. InSAR satellite data collected since 1992 have revealed the presence of several subsiding areas in the basin, such as the south-eastern portion of Pistoia city. Sentinel-1 persistent scatterer interferometry measurements for 2015–2018 confirmed the long-term subsidence of this area, associated with intense horticulture (plant nurseries). At the same time, Sentinel-1 data revealed the unexpected movement of Pistoia historic center, which has always been considered stable in the past. To identify the complex relationship between aquifer conditions and ground displacement, a hydrogeologic model of the Pistoia aquifers was developed, applying an integrated modelling procedure. This approach was firstly tested in a small pilot basin, to confirm the reliability of the numerical procedure, obtaining promising results. Hydrodynamic-parameter distributions, calibrated and validated by means of Sentinel-1 PSI measurements, suggest that subsidence in Pistoia area is probably related with the combined impacts of groundwater extraction and highly compressible aquitards. To evaluate the potential evolution of ground displacement, numerical simulations were extended until 2050, using regional and global climate model data, analyzing three different pumping-rate scenarios. This, together with damage information of buildings collected on the field, led to the development of several subsidence hazard maps of Pistoia city that display the influence of groundwater extraction in controlling land subsidence in the area. The present study enhances the importance of developing proper groundwater management policies, especially in alluvial aquifers made of fine compressible sediments, in order to sustainably utilize underground freshwater resources and to avoid related side effects. It also emphasizes the role of integrated numerical simulations and the necessity to consider surficial network and groundwater as a unique interacting system, when developing basin scale hydrogeologic analysis., Landabsenkungen stellen eine der wichtigsten Naturgefahren dar, die mehrere Länder auf der Welt betreffen und möglicherweise Schäden an Gebäuden und Infrastruktur verursachen. Das Firenze-Prato-Pistoia-Becken verfügt über langjährige Erfahrung mit Bodenverformungen im Zusammenhang mit der Grundwasserentnahme. InSAR-Satellitendaten, die seit 1992 gesammelt wurden, haben gezeigt, dass im Becken mehrere Absenkungsgebiete vorhanden sind, beispielsweise der südöstliche Teil der Stadt Pistoia. Sentinel-1-Messungen für den Zeitraum 2015–2018 bestätigten die langfristige Absenkung dieses Gebiets, die mit einem intensiven Gartenbau verbunden ist. Gleichzeitig enthüllten Sentinel-1-Daten die unerwartete Bewegung des Zentrums von Pistoia, das in der Vergangenheit immer als stabil angesehen wurde. Um die Beziehung zwischen den Bedingungen des Grundwasserleiters und der Bodenverschiebung zu identifizieren, wurde ein hydrogeologisches Modell der Pistoia-Grundwasserleiter unter Anwendung eines integrierten Modellierungsverfahrens entwickelt. Dieser Ansatz wurde zunächst in einem Pilotbecken getestet, um die Zuverlässigkeit des Verfahrens zu bestätigen und vielversprechende Ergebnisse zu erzielen. Hydrodynamische Parameterverteilungen, die mithilfe von Sentinel-1-Messungen kalibriert und validiert wurden, legen nahe, dass das Absinken im Gebiet von Pistoia wahrscheinlich mit den kombinierten Auswirkungen der Grundwassergewinnung und hochkomprimierbarer Aquitards zusammenhängt. Um die mögliche Entwicklung der Bodenverschiebung zu bewerten, wurden Simulationen bis 2050 erweitert, wobei prädiktive Klimamodelldaten verwendet und drei verschiedene Pumpraten-Szenarien analysiert wurden. Dies führte zusammen mit Schadensinformationen von Gebäuden zur Entwicklung mehrerer Karten der Senkungsgefahr der Stadt Pistoia, die den Einfluss der Grundwassergewinnung auf die Kontrolle der Bodensenkung in der Region zeigen. Die vorliegende Studie unterstreicht die Bedeutung einer angemessenen Grundwassermanagementpolitik, insbesondere bei Schwemmlandgrundwasserleitern aus feinen komprimierbaren Sedimenten, um die unterirdischen Süßwasserressourcen nachhaltig zu nutzen und damit verbundene Nebenwirkungen zu vermeiden. Es unterstreicht auch die Rolle integrierter numerischer Simulationen und die Notwendigkeit, das Oberflächennetz und das Grundwasser als ein einzigartiges Wechselwirkungssystem zu betrachten, wenn hydrogologische Analysen im Beckenmaßstab entwickelt werden.

We present a middleware-based protocol that reliably synchronizes large samples consisting of multiple frames efficiently and within application level QoS requirements over a lossy wireless channel. The protocol uses a custom retransmission scheme, exploiting the latency requirements on sample level for frame level scheduling. It can be integrated into the popular DDS middleware. We investigate some technical limits of such a protocol and compare it to existing error protocols in the software stack and in the wireless protocol and combinations thereof. The comparison is based on an Omnet++ simulation using an established wireless channel error model. For evaluation, we take a use case from automated valet parking where infrastructure data provided via a wireless link augments in-vehicle sensor data. The use case respects the related safety requirements. Results show that the application awareness of the presented protocol, significantly improves service availability by transmitting data efficiently in time even under higher frame error rates.

Within the project ‘ARIEL’ an electrical turbo compressor unit for fuel cell applications is deeply investigated. The necessary drive inverter is especially designed for high fundamental frequency and high switching frequency to cope with the requirements of the implemented electrical machine. This paper presents investigations on the inverter’s efficiency and its prospective lifetime at different stages of the development. In the design process different wide band gap power semiconductor devices in discrete packages are evaluated in terms of the achievable power density and efficiency, both by simulations and measurements. Finally, an optimised design using surface mount silicon carbide MOSFETs is developed. Compared to a former inverter design using silicon devices in a three-level topology, the power density of the inverter is significantly increased. The lifetime of power electronic systems is often limited by the lifetime of the power semiconductor devices. Based on loss calculations and the resulting temperature swing of the virtual junction the lifetime of the inverter is estimated for the most frequent operating points and for different mission profiles.

Thermal noise of optical components is one of the sensitivity limiting effects in gravitational wave detectors, laser stabilization cavities and many other experiments in basic research. However, current methods for the computation of thermal noise are limited for an application in either infinitely large or symmetrically illuminated masses. I present a general method of computing thermal noise of arbitrary finite-sized masses in optical interferometers. The presented approach generalizes state-of-the-art methods for an application in arbitrary shaped optical elements illuminated by arbitrary spatial light distributions. Furthermore, I show the application of the presented approach to compute thermal noise of maladjusted mirrors in Fabry-Perot interferometers. It is shown that the noise can be reduced by off-axis illumination in the case of thin mirrors.

The publication contains the dataset which is a supplemental material for the paper "A discrete choice model for solving conflict situations between pedestrians and vehicles in shared space" (arXiv preprint arXiv:1709.09412). Positions of traffic participants relevant to the study: pedestrians, cyclists and motorized vehicles, are included which can be used derive movement trajectories with corresponding speeds and accelerations. Original study is about shared space interactions, however the dataset can be used to study general interactions of traffic participants in heterogeneous environment.

The purpose of this work is to simulate the powder compaction of pharmaceutical materials at the microscopic scale in order to better understand the interplay of mechanical forces between particles, and to predict their compression profiles by controlling the microstructure. For this task, the new framework of multi-contact discrete element method (MC-DEM) was applied. In contrast to the conventional discrete element method (DEM), MC-DEM interactions between multiple contacts on the same particle are now explicitly taken into account. A new adhesive elastic-plastic multi-contact model invoking neighboring contact interaction was introduced and implemented. The uniaxial compaction of two microcrystalline cellulose grades (Avicel® PH 200 (FMC BioPolymer, Philadelphia, PA, USA) and Pharmacel® 102 (DFE Pharma, Nörten-Hardenberg, Germany) subjected to high confining conditions was studied. The objectives of these simulations were: (1) to investigate the micromechanical behavior; (2) to predict the macroscopic behavior; and (3) to develop a methodology for the calibration of the model parameters needed for the MC-DEM simulations. A two-stage calibration strategy was followed: first, the model parameters were directly measured at the micro-scale (particle level) and second, a meso-scale calibration was established between MC-DEM parameters and compression profiles of the pharmaceutical powders. The new MC-DEM framework could capture the main compressibility characteristics of pharmaceutical materials and could successfully provide predictions on compression profiles at high relative densities.

The alternative control concept using emission from the machine has the potential to reduce energy consumption in HVAC systems. This paper reports on a study of alternative inputs for a control system of HVAC using machine learning algorithms, based on data that are gathered in a welding area of an automotive factory. A data set of CO2, fine dust, temperatures and air velocity was logged using continuous and gravimetric measurements during two typical production weeks. The HVAC system was reduced gradually each day to trigger fluctuations of emission. The data were used to train and test various machine learning models using different statistical indices, consequently to choose a best fit model. Different models were tested and the Long Short-Term Memory model showed the best result, with 0.821 discrepancy on R2. The gravimetric samples proved that the reduction of air exchange rate does not correlate to escalation of fine dust linearly, which means one cannot rely on just gravimetric samples for HVAC system optimization. Furthermore, by using machine learning algorithms, this study shows that by using commonly available low cost sensors in a production hall, it is possible to correlate fine dust data cost effectively and reduce electricity consumption of the HVAC.

The article reports on the influence of annealing PVDF in an autoclave process on the PVDF phase composition. DSC, FTIR and XRD measurements serve to observe the phase changes in an already stretched, polarised and β-phase rich film. Annealing was conducted between 90 and 185 ∘C to cover a broad range of curing processes in an autoclave. The β-phase is found to be stable up to near the melting range at 170 ∘C. At 175 ∘C, the non-piezoelectric α-phase dominates and the piezoelectric γ- and γ′-phases appear. The γ-phase grows at elevated temperatures and replaces the β-phase. This observation stresses the importance of developing new methods to reactivate the polarisation after annealing, in particular for the integration of PVDF as a sensor in laminated structures, such as CFRP.

In lithium-ion battery manufacturing, wetting of active materials is a time-critical process. Consequently, the impact of possible process chain extensions such as lamination needs to be explored to potentially improve the efficiency of the electrode and separator stacking process in battery cell manufacturing. This paper addresses the research gap of the unexplored effects of lamination on the wetting rate of electrode-separator assemblies in pouch cells. Based on the triangulation of three measurement techniques (gravimetric, optical, electrochemical), a correlation between lamination and wettability of electrode-separator assemblies is experimentally demonstrated, thus providing an important research contribution.

This tutorial E-book is based on the long-standing experience of teaching railway operations and signalling at TU Braunschweig and other universities and higher vocational training institutions in different parts of the world. It explains the fundamental principles all railway signalling systems have in common. This is done in a generic way that does not focus on specific national solutions. It covers basic elements and terms, principles for safe train separation, interlocking principles, automatic train protection, and level crossing protection. It also contains a glossary with definitions of relevant terms., Dieses E-Book basiert auf dem Inhalt meiner gleichnamigen, englischsprachigen Vorlesung an der TU Braunschweig, die ich in ähnlicher Form seit vielen Jahren im Rahmen von Lehrkooperationen regelmäßig auch an mehreren ausländischen Universitäten halte. Ich möchte auf diesem Wege das darin in konzentrierter Form gesammelte Wissen der Allgemeinheit zugänglich machen. Es dient für die genannten Lehrveranstaltungen im In- und Ausland inzwischen auch als Vorlesungsskript. In der 2. Auflage wurde vor allem der Abschnitt zum European Train Control System (ETCS) zur Anpassung an aktuelle Entwicklungen überarbeitet und ergänzt.

Organic thin-film lasers gain interest as potential light sources for application in diverse fields. With the current development, they hold variety of benefits such as: low-cost, high-performance, and color-tunability. Meanwhile, the production is not complicated because both the resonator and the gain medium can be assembled by solution-processable organic materials. To our knowledge, information about using poly(methyl methacrylate) (PMMA) as a matrix for organic dye lasers was insubstantial. Herein, the feasibility of using organic dye-doped PMMA as an organic dye laser was tested. Six different sample designs were introduced to find out the best sample model. The most optimum result was displayed by the sample design, in which the gain medium was sandwiched between the substrate and the photoresist layer with grating structure. The impact of dye concentration and grating period on peak wavelength was also investigated, which resulted in a shift of 6 nm and 25 nm, respectively. Moreover, there were in total six various organic dyes that could function well with PMMA to collectively perform as ‘organic dye lasers’, and they emitted in the range of 572 nm to 609 nm. Besides, one of the samples was used as a sensor platform. For instance, it was used to detect the concentration of sugar solutions.

In 5G and Beyond networks the ultra-densification of networks will require ultra-high backhaul capacities for a very large number of base station locations, especially in urban areas. Since fibre connections will not be available everywhere, the use of spectrum at 300 GHz and beyond might enable the complementary use of wireless backhaul solutions to nearby fibre connected hubs. In some cases a line-of-sight connection is not available and the backhaul connection might be realized using one refection. In this paper a planning algorithm is presented, which automatically identifies possible wireless links taking into account none-line-of-sight connections in backhaul networks arranged in star topology., 2021 XXXIVth General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS)

Shape-sensing in real-time is a key requirement for the development of advanced algorithms for concentric tube continuum robots when safe interaction with the environment is important e.g., for path planning, advanced control, and human-machine interaction. We propose a real-time shape-estimation algorithm for concentric tube continuum robots based on the force-torque information measured at the tubes’ basis. It extends a shape estimation algorithm for elastic rods based on discrete Kirchhoff rod theory. For simplicity and efficiency of calculation, we combine it with a model under piece-wise constant curvature assumption, in which we model a concentric tube continuum robot as a combination of segments of planar constant curvatures lying on different equilibrium planes. We evaluate our approach for a single and two combined additively manufactured tubes and achieve an estimation frequency of 333 Hz for two combined tubes with a mean deviation along the backbone of the tubes of 1.91–5.22 mm.

This Perspective discusses the literature related to two-phase biocatalysis in microfluidic droplets. Enzymes used as catalysts in biocatalysis are generally less stable in organic media than in their native aqueous environments; however, chemical and pharmaceutical compounds are often insoluble in water. The use of aqueous/organic two-phase media provides a solution to this problem and has therefore become standard practice for multiple biotransformations. In batch, two-phase biocatalysis is limited by mass transport, a limitation that can be overcome with the use of microfluidic systems. Although, two-phase biocatalysis in laminar flow systems has been extensively studied, microfluidic droplets have been primarily used for enzyme screening. In this Perspective, we summarize the limited published work on two-phase biocatalysis in microfluidic droplets and discuss the limitations, challenges, and future perspectives of this technology.

Production of high-aspect-ratio silicon (Si) nanowire-based anode for lithium ion batteries is challenging particularly in terms of controlling wire property and geometry to improve the battery performance. This report demonstrates tunable optimization of inductively coupled plasma reactive ion etching (ICP-RIE) at cryogenic temperature to fabricate vertically-aligned silicon nanowire array anodes with high verticality, controllable morphology, and good homogeneity. Three different materials [i.e., photoresist, chromium (Cr), and silicon dioxide (SiO2)] were employed as masks during the subsequent photolithography and cryogenic ICP-RIE processes to investigate their effects on the resulting nanowire structures. Silicon nanowire arrays with a high aspect ratio of up to 22 can be achieved by tuning several etching parameters [i.e., temperature, oxygen/sulfur hexafluoride (O2/SF6) gas mixture ratio, chamber pressure, plasma density, and ion energy]. Higher compressive stress was revealed for longer Si wires by means of Raman spectroscopy. Moreover, an anisotropy of lattice stress was found at the top and sidewall of Si nanowire, indicating compressive and tensile stresses, respectively. From electrochemical characterization, half-cell battery integrating ICP-RIE-based silicon nanowire anode exhibits a capacity of 0.25 mAh cm−2 with 16.67% capacity fading until 20 cycles, which has to be improved for application in future energy storage devices.

The synthesis of nanoparticles in microchannels promises the advantages of small size, uniform shape and narrow size distribution. However, only with insights into the mixing processes can the most suitable designs and operating conditions be systematically determined. Coaxial lamination mixers (CLM) built by 2-photon polymerization can operate long-term stable nanoparticle precipitation without fouling issues. Contact of the organic phase with the microchannel walls is prevented while mixing with the aqueous phase is intensified. A coaxial nozzle allows 3D hydrodynamic focusing followed by a sequence of stretch-and-fold units. By means of a digital twin based on computational fluid dynamics (CFD) and numerical evaluation of mixing progression, the influences of operation conditions are now studied in detail. As a measure for homogenization, the mixing index (MI) was extracted as a function of microchannel position for different operating parameters such as the total flow rate and the share of solvent flow. As an exemplary result, behind a third stretch-and-fold unit, practically perfect mixing (MI>0.9) is predicted at total flow rates between 50 µL/min and 400 µL/min and up to 20% solvent flow share. Based on MI values, the mixing time, which is decisive for the size and dispersity of the nanoparticles, can be determined. Under the conditions considered, it ranges from 5 ms to 54 ms. A good correlation between the predicted mixing time and nanoparticle properties, as experimentally observed in earlier work, could be confirmed. The digital twin combining CFD with the MI methodology can in the future be used to adjust the design of a CLM or other micromixers to the desired total flow rates and flow rate ratios and to provide valuable predictions for the mixing time and even the properties of nanoparticles produced by microfluidic antisolvent precipitation.

A physics-based optimisation framework is developed to investigate the potential advantages of novel technologies on the energy efficiency of a midrange passenger aircraft. In particular, the coupled-adjoint aerostructural analysis and optimisation tool FEMWET is modified to study the effects of active flow control at different load cases for conventional and unconventional wing configurations. This multidisciplinary design optimisation (MDO) framework presents the opportunity to optimise the wing considering static aeroelastic effect and, by its gradient-based method, save substantial computational time compared to high-fidelity tools, keeping a satisfying level of accuracy. Two different configurations are analysed: a forward- and backward-swept wing aircraft, developed inside the Cluster of Excellence SE2A (Sustainable and Energy-Efficient Aviation). The forward-swept configuration is sensitive to the aeroelastic stability effect, and the backward configuration is influenced by the aileron constraint. They may lead to a weight increment. Sensitivity studies show the possible role of key parameters on the optimisation results. The highest fuel weight reduction achievable for the two configurations is 5.6% for the forward-swept wing and 9.8% for the backward configuration. Finally, both optimised wings show higher flexibility.

This study presents an approach for targeted comminution of component mixtures within a wet-operated stirred media mill. In the first step, a general understanding of the interactions between individual components on the grinding result with mixtures could be gained with basic experiments and following our former research work. In particular, a protective effect of the coarser particles on the fines could be elucidated. These findings were used to develop a process for the production of a battery slurry containing fine ground silicon particles as well as dispersed carbon black and graphite particles. By a tailored sample preparation applying a combination of particle dissolution and separation, the particle size distributions of carbon black and graphite particles were analyzed separately within the produced battery slurries. Based on the selective particle size analysis, the slurry preparation could be transferred from a complex multistage batch process using a dissolver to a stirred media mill, which was finally operated in a continuous one-passage mode. The prepared slurries were subsequently further processed to silicon-rich anodes using a pilot scale coating and drying plant. Afterward, the produced anodes were electrochemically characterized in full cells. The cell results prove a comparable electrochemical behavior of anode coatings derived from a dissolver- or mill-based slurry production process. Therefore, we could demonstrate that it is possible to integrate the mixing process for the production of multicomponent slurries into the comminution process for the preparation of individual materials upstream. Even with nearly identical starting sizes of their feed materials, the targeted particle size distributions of the single components can be reached, taking into account the different material-dependent particle strengths and sequential addition of single components to the multicomponent comminution process.

When tailoring porous absorbers in acoustic applications, an appropriate acoustic material model, as well as the relationship between the material model parameters and the microscale geometry of the material, is indispensable. This relationship can be evaluated analytically only for few simple material geometries. Machine-learning models can close this gap for complex materials, but due to their black-box nature, the interpretability of obtained inferences is rather low. Therefore, an existing neural network model that predicts the acoustic properties of a porous material based on the microscale geometry is subject to statistics-based sensitivity analysis. This is conducted to gain insights into the relationship between the microscale geometry and the acoustic material parameters of a generic bar-lattice design porous material. Although it is a common approach in the field of explainable artificial intelligence research, this has not been widely investigated for porous materials yet. By deriving statistics-based sensitivity measures from the neural network model, the explainability and interpretability is increased and insights into the relationship of the acoustic properties and their microscale geometry of the porous specimen can be obtained. The results appear plausible and comparable to existing studies available in the literature, showing if and how the bar-lattice geometry influences the acoustic material parameters. Moreover, it could be shown that the applied global sensitivity analysis method allows us to not only derive a one-to-one parameter impact relation, but also reveals interdependencies that are important to address during a material tailoring process.

Extreme hydrodynamic events such as hurricanes or tsunamis threaten coastal regions in particular. Such hazards must be assessed and appropriately incorporated into building codes to mitigate casualties and damages to coastal structures. Guidelines are often developed through experimental investigations that assume buildings remain rigid during hydrodynamic loading. To challenge this ‘rigid building paradigm’, test specimens were designed to replicate the deformation characteristics of an idealized light-frame timber structure using Froude-Cauchy similarity. Subsequently, a large-scale experimental study was conducted at the Large Wave Flume of the Coastal Research Center in Hannover. Hydrodynamic loads and load gradients were investigated to describe both the influence of an elasto-plastically modeled test specimen compared to a rigid reference model and the effect of load history on the structural loads. Finally, the collapse sequences of elasto-plastic specimens were extracted from high-speed photographs and classified into three failure mechanisms. In this study, data analyses are presented with the intention to not only inform local authorities for future development of guidelines but also serve as calibration and validation data for improving numerical methods., Coastal Engineering, vol. Vol. 177, 2022

Monitoring process parameters in the manufacture of composite structures is key to ensuring product quality and safety. Ideally, this can be done by sensors that are embedded during production and can remain as devices to monitor structural health. Extremely thin foil-based sensors weaken the finished workpiece very little. Under ideal conditions, the foil substrate bonds with the resin in the autoclaving process, as is the case when polyetherimide is used. Here, we present a temperature sensor as part of an 8 µm thick multi-sensor node foil for monitoring processing conditions during the production and structural health during the lifetime of a construction. A metallic thin film conductor was shaped in the form of a space-filling curve to suppress the influences of resistance changes due to strain, which could otherwise interfere with the measurement of the temperature. FEM simulations as well as experiments confirm that this type of sensor is completely insensitive to the direction of strain and sufficiently insensitive to the amount of strain, so that mechanical strains that can occur in the composite curing process practically do not interfere with the temperature measurement. The temperature sensor is combined with a capacitive sensor for curing monitoring based on impedance measurement and a half-bridge strain gauge sensor element. All three types are made of the same materials and are manufactured together in one process flow. This is the key to cost-effective distributed sensor arrays that can be embedded during production and remain in the workpiece, thus ensuring not only the quality of the initial product but also the operational reliability during the service life of light-weight composite constructions.

Lithium-ion batteries are a key technology for electromobility, thus, quality control in cell production is a central aspect for the success of electric vehicles. The detection of defects and poor insulation behavior of the separator is essential for high-quality batteries. Optical quality control methods in cell production are unable to detect small but still relevant defects in the separator layer, e.g., pinholes or particle contaminations. This gap can be closed by executing high-potential testing to analyze the insulation performance of the electrically insulating separator layer in a pouch cell. Here, we present an experimental study to identify different separator defects on dry cell stacks on the basis of electric voltage stress and mechanical pressure. In addition, finite element modeling (FEM) is used to generate physical insights into the partial discharge by examining the defect structures and the corresponding electric fields, including topographical electrode roughness, impurity particles, and voids in the separator. The test results show that hard discharges are associated with significant separator defects. Based on the study, a voltage of 350 to 450 V and a pressure of 0.3 to 0.6 N/mm2 are identified as optimum ranges for the test methodology, resulting in failure detection rates of up to 85%.

Current research in the field of aviation considers actively controlled high-lift structures for future civil airplanes. Therefore, pressure data must be acquired from the airfoil surface without influencing the flow due to sensor application. For experiments in the wind and water tunnel, as well as for the actual application, the requirements for the quality of the airfoil surface are demanding. Consequently, a new class of sensors is required, which can be flush-integrated into the airfoil surface, may be used under wet conditions—even under water—and should withstand the harsh environment of a high-lift scenario. A new miniature silicon on insulator (SOI)-based MEMS pressure sensor, which allows integration into airfoils in a flip-chip configuration, is presented. An internal, highly doped silicon wiring with “butterfly” geometry combined with through glass via (TGV) technology enables a watertight and application-suitable chip-scale-package (CSP). The chips were produced by reliable batch microfabrication including femtosecond laser processes at the wafer-level. Sensor characterization demonstrates a high resolution of 38 mVV−1 bar−1. The stepless ultra-smooth and electrically passivated sensor surface can be coated with thin surface protection layers to further enhance robustness against harsh environments. Accordingly, protective coatings of amorphous hydrogenated silicon nitride (a-SiN:H) and amorphous hydrogenated silicon carbide (a-SiC:H) were investigated in experiments simulating environments with high-velocity impacting particles. Topographic damage quantification demonstrates the superior robustness of a-SiC:H coatings and validates their applicability to future sensors.

Für die Bewirtschaftung des Wasserdargebots in Form der Wasserversorgung und -entsorgung aber auch für den Hochwasserschutz auf kommunaler Ebene sind verschiedene wasserwirtschaftliche Bauwerke notwendig. Eine wichtige Planungskenngröße für die Bemessung und den Betrieb solcher Bauwerke sind unter anderem Starkregenangaben. Diese Angaben werden auf Basis von beobachteten oder modellierten Niederschlagszeitreihen erstellt. Mittels Extremwertverteilungsfunktionen werden Quantilwerte berechnet, die weiterführend für die Festlegung von Bemessungswerten verwendet werden können. Die klassischen und derzeit angewendeten Verfahren der Extremwertstatistik setzen stationäre Zeitreihen voraus. Dem stehen prognostizierte, klimatische Veränderungen und die bereits beobachtete Zunahme von Starkregenereignissen gegenüber, sodass die stationären Verfahren unter Umständen nicht mehr ohne Weiteres anwendbar sind. Mittels erweiterter statistischer Verfahren können die auch als Instationaritäten bezeichneten, langzeitlichen oder auch abrupten Änderungen in Zeitreihen entsprechend berücksichtigt und modelliert werden. In der vorliegenden Dissertation wird ein instationärer, extremwertstatistischer Ansatz zur Berechnung von Regenhöhen als Planungskenngröße entwickelt. Es erfolgt eine zeitabhängige Berechnung von Quantilwerten, sodass Instationaritäten in den Beobachtungsdaten berücksichtigt werden können. Der entwickelte Berechnungsansatz nutzt regionalisierte Klimaprojektionen zur Modellierung zeitabhängiger Parameter der Verallgemeinerten Extremwertverteilung. Diese Parameter werden für jeden Zeitpunkt über alle Dauerstufen hinweg optimiert. Die anschließend berechneten, instationären Quantilwerte werden in Abhängigkeit ausgewählter Perzentile und einer geplanten Bauwerkslebensdauer in eine zeitunabhängige Planungskenngröße überführt. Der Ansatz wird für 49 Niederschlagsstationen in Nordrhein-Westfalen ausgewertet, wobei eine Detailbetrachtung und -auswertung anhand der Niederschlagsstation Detmold_KA erfolgt. Die Berechnungsergebnisse werden mit Koordinierten Starkniederschlags-Regionalisierungs-Auswertungen (KOSTRA-DWD 2010R) und Starkregenangaben verglichen. Weiterführend wird die Auswirkung der sich verändernden Bemessungsgrößen exemplarisch anhand eines Niederschlags-Abfluss-Modells dargestellt., Both for the management of water supply and for the flood protection at municipal level various water management infrastructures are used. The infrastructure design is primarily based on rainfall depth-duration-frequency (DDF) curves, which are calculated on the basis of observed or modeled precipitation time series. Extreme value distribution functions are applied to calculate quantiles which are then used as design values for assessing water infrastructure. The common and currently applied methods of extreme value statistics assume stationary time series. In contrast, there are predicted climatic changes and the already observed increase of heavy rainfall events. The stationary procedures therefore may no longer be readily applied. Accordingly, long-term or even abrupt changes in time series, also called non-stationarities, can be considered and modeled by the means of extended statistical methods. The underlying thesis develops a non-stationary extreme value approach for calculating DDF-curves. Furthermore, a time-dependent calculation of quantile values is carried out by taking into account non-stationarities in the observed data. As a first step, time-dependent parameters of the Generalized Extreme Value Distribution are modeled using regionalized climate projections. These parameters are optimized for each timestep and all duration levels. Then, subsequently calculatet transient quantile values are transformed into a time-independent design value depending on selected percentiles and a planned life period of the structure to be designed. The developed approach is evaluated for 49 rain gauges in North Rhine-Westphalia. A detailed evaluation is carried out on the basis of the rain gauge Detmold_KA. The results are compared with Koordinierten Starkniederschlags-Regionalisierungs-Auswertungen (KOSTRA-DWD 2010R) and DDF-curves. Moreover, the effect of the changing design values is exemplified by a rainfall-runoff model.

Integrating foil sensors into fibre-reinforced plastics offers the advantage of making manufacturing measurable with spatial resolution and thus simplifies quality control. One challenge here is the possible negative influence of the integrated sensors on the mechanical behaviour of the structure. This article shows how the different parts of a film sensor influence important mechanical strength parameters of fibre composites. A comparison of two thermoplastic carrier films shows that by choosing polyetherimide (PEI) instead of polyimide (PI), a considerably more advantageous failure behaviour of the composite is achieved. While integrated PI films reduce the interlaminar shear strength by 68%, no impairment is noticeable due to PEI films. For the critical energy release rate, PEI-based film sensors even lead to a significant increase, while a significant deterioration of 85% can be observed for PI-based sensors. However, not only the film substrate plays a decisive role for the interlaminar shear strength, but also the sensor structures themselves. In this article, sensor structures made of gold were investigated. The decisive parameter for the impairment seems to be the area share of gold structures in the sensor. For a sensor pattern made of gold lines with an area filling of 50%, a reduction of the interlaminar shear strength of up to 25% was observed depending on the angle between the shear stress and the gold lines. No impairment was observed for sensor structures with less gold area. The results show that PEI substrates can be a superior alternative for sensor integration into fibre composites and suggest that there is a trade-off between sensitivity and degradation of mechanical properties when designing interdigital sensors.

In tsunami hazard assessment, the vulnerable area is determined using numerical models, which calculate the tsunami propagation and the inundation extent. Large-scale depth-averaged models, e.g. based on non-linear shallow water (NLSW) equations, are commonly applied. In such models, a selected Manning’s coefficient is generally applied to account for the effect of the bottom surface roughness. However, macro-roughness elements (MRE) such as buildings and tree vegetation generally form also part of coastal areas. Using purely empirical Manning’s coefficients to account for such large objects is not physically sound and might result in large uncertainties. To date, there is not generally applicable NLSW model available for adequately considering MRE-induced energy losses during tsunami inundation. This Ph.D. thesis attempts to contribute to a better understanding of the effects of relevant MRE parameters such as shape, size, and arrangement of the MREs on tsunami bore propagation and inundation. In phase 1 of this study, a three-dimensional Reynolds-averaged Navier-Stokes (RANS) model is systematically validated. In phase 2, the RANS model is used in a parameter study to create a database for flow parameters associated to MRE configurations, varying shape, size, height, arrangement, and density of MRE. In phase 3, the most relevant MRE parameters and flow regimes are determined and are carefully formulated so that they are easily obtainable for tsunami modelling. The energy losses are formulated by considering inertia and drag losses in analogy to the Morison equation. In phase 4, the MRE formula is implemented in the NLSW model COMCOT. Finally, the performance of the MRE formula is evaluated by comparing the results with well-documented physical experiments (Park et al., 2013) and with commonly used “equivalent roughness” approaches. The following findings are obtained: (i) In a group of MRE, an upstream zone and an inner zone can be distinguished; (ii) The shape, arrangement angle, relative spacing (ratio between blocked and total cross-section) and relative height (ratio between height of submerged part of MRE and flow depth) are the most relevant parameters; (iii) The MRE model leads to improved results compared to commonly used equivalent roughness models; (iv) The MRE model does not require calibration., In der Tsunami-Gefahrenbewertung wird das gefährdete Gebiet mit Hilfe von numerischen Modellen bestimmt, die u.A. die Überflutungsfläche berechnen. Meist werden großskalige, tiefengemittelte Modelle verwendet, die z.B. auf der nicht-linearen Flachwassergleichung (NLSW) basieren. In diesen Modellen wird meist ein Manning-Beiwert angewandt, um die Bodenrauheit zu berücksichtigen. Jedoch bestehen küstennahe Gebiete in der Regel auch aus sogenannten Makro-Rauheitselementen (MRE) wie Gebäuden und Vegetation. Allein rein empirische Manning-Beiwerte für die Berücksichtigung so großer Hindernisse zu verwenden ist physikalisch nicht korrekt und hat große Modell-Unsicherheiten zur Folge. Derzeit liegt kein NLSW-Modell vor, das MRE-induzierte Energieverluste bei Tsunami-Überflutungen adäquat berücksichtigt. In dieser Doktor-Arbeit wurde versucht zu einem besseren Verständnis relevanter MRE-Parameter, wie z.B. Form, Größe und Anordnung, auf die Tsunami-Ausbreitung und -Überflutung beizutragen. In Phase 1 wurde ein drei-dimensionales Reynolds-gemitteltes Navier-Stokes- (RANS)-Modell systematisch validiert. In Phase 2 wurde das RANS-Modell in einer Parameterstudie angewandt und eine Datenbasis für Fließparameter in Relation zu MRE-Konfigurationen erstellt, die in Form, Größe, Höhe, Anordnung und Dichte der MRE variierten. In Phase 3 wurden die maßgebenden MRE-Parameter ermittelt. Die Parameter wurden sorgfältig gebildet, so dass sie für die Tsunami-Modellierung leicht zu bestimmen bzw. verfügbar sind. Die Energieverluste werden in Analogie zur Morison-Gleichung als Trägheits- und Widerstandsverluste formuliert. In Phase 4 wird die MRE-Formel in das NLSW-Modell COMCOT implementiert. Schließlich wird die Leistungsfähigkeit der MRE-Formel durch den Vergleich der Ergebnisse mit gut dokumentieren Laborexperimenten (Park et al., 2013) und mit zwei der herkömmlichen „äquivalenten Rauheitsansätzen“ bewertet. Die folgenden Erkenntnisse wurden gewonnen: (i) In einer Gruppe von MRE muss zwischen einer Zufluss-seitigen Rand- und einer inneren Zone unterschieden werden. (ii) Die Parameter Form, Anordnungswinkel, relativer Zwischenraum (Verhältnis blockierter zu gesamter Querschnittsfläche) und der relativen Höhe (Verhältnis Höhe (des überfluteten Teils) der MRE zu Fließtiefe) sind maßgebend. (iii) Das MRE-Modell führt im Vergleich zum herkömmlich verwendeten äquivalenten Rauheitsansätzen zu verbesserten Ergebnissen. (iv) Das MRE-Modell benötigt keine Kalibrierung.

Nanomaterials have been used in improving the performance of construction materials due to their compacting micro-structure effect and accelerating cement hydration reaction. Considering the brittle characteristic of fiber reinforced polymer (termed as FRP) tube encased concrete and inferior properties of recycled concrete, nanoparticles were used in FRP tube encased recycled aggregate concrete. The axial compressive performance of FRP tube used in recycled concrete treated with nanoparticles strengthening, termed as FRP-NPRC, were investigated by axial compression experiments and theoretical analysis. Five experimental variables were considered including (1) the dosages and (2) varieties of nanoparticles (i.e. 1% and 2% of nanoSiO2, 1% and 2% of nanoCaCO3), (3) replacement ratios of recycled coarse aggregates (termed as RCAs) (0%, 50%, 70% and 100%) the RCAs were mainly produced from the waste cracked bricks, (4) the number of glass FRP (GFRP) tube layers (2, 4 and 6-layer) and (5) the mixing methods of concrete. Results indicate that the combination of FRP confinement and nanoparticle modification in recycled concrete exhibited up to 76.2% increase in compressive strength and 7.62 times ductility improvement. Furthermore, a design-oriented stress–strain model on the basis of the ultimate condition analysis were executed to evaluate the stress–strain property of this strengthened component.

In der vorliegenden Arbeit wird eine quantenbasierte Referenzspannungsrauschquelle für metrologische Anwendungen in der primären Rauschthermometrie aufgebaut und charakterisiert. Das Ziel der Arbeit besteht darin die Rauschquelle für den Betrieb im vorgesehenen Signalfrequenzbereich bis 225 kHz zu optimieren, um eine Amplitudengenauigkeit im einstelligen μV/V-Bereich bei zukünftigen Rauschthermometer-Kalibrierungen zu gewährleisten. Das System basiert auf einer Serienschaltung pulsgetriebener Josephson-Kontakte und ermöglicht es quantenbasierte Spannungen zu erzeugen. Nach der umfassenden Systemcharakterisierung und -beschreibung wird die exzellente Funktionalität, welche die Josephson-Spannungsrauschquelle bietet, experimentell demonstriert. Die Optimierung der Probenstangenabschirmung und Filterung des Pulse-Bias-Stroms bewirkt eine Reduktion potentieller Störeinflüsse durch elektromagnetische Interferenz und Übersprechen. Erstmalig erfolgen im Verlauf der Arbeit Wechselspannungsvergleiche zwischen zwei pulsgetriebenen Josephson-Spannungsnormalen zur Überprüfung der Amplitudengenauigkeit für einen Frequenzbereich bis 500 kHz. Die hochfrequenten Amplitudenabweichungen durch die Ausgangsverkabelung und den Pulse-Bias-Strom werden systematisch analysiert. Die Messergebnisse stimmen sehr gut mit dem erstellten Modell über ein und liegen für alle untersuchten Konfigurationen nach Korrektur der erwarteten Frequenzabhängigkeit innerhalb ±1 μV/V bis 500 kHz. Abschließend erzeugt die optimierte Josephson-Spannungsrauschquelle verzerrungsarme Mehrtonwellenformen zur Kalibrierung des Frequenzgangs und Untersuchung der Signalverstärkungslinearität kritischer Rauschthermometerkomponenten. Der Vergleich unterschiedlicher Mehrtonwellenformen demonstriert den Einfluss von Intermodulationsverzerrung während der Kalibrierung. Es kann eine Verstärkungslinearität des Signalpfads einschließlich des Analog-Digital-Umsetzers und eines Prototyp-Verstärkers für das neue Thermometer innerhalb ±2 μV/V für eingangsbezogene Rauschpegel von 9,7 μV bis 465 μV experimentell nachgewiesen werden. Die Ergebnisse der Arbeit belegen die Einsatztauglichkeit und Genauigkeit der Josephson-Spannungsrauschquelle zur Kalibrierung des neuen Rauschthermometers bis 225 kHz. Darüber hinaus liefern die Erkenntnisse substanzielle Beiträge zum vertieften Verständnis pulsgetriebener Josephson-Spannungsnormale bis 500 kHz. Ferner tragen die Ergebnisse zur Verbesserung des zukünftigen Rauschthermometers bei., In this thesis a quantum-based reference voltage noise source for metrological applications in primary noise thermometry is built and characterised. The main objective of the work is to optimise the noise source for operation in the frequency range up to 225 kHz and to ensure amplitude accuracy at the single-digit μV/V level in future noise thermometer calibrations. The system is based on pulse-driven Josephson junctions connected in series and enables quantum-based voltages to be generated. After the comprehensive system characterisation and description, the excellent functionality offered by the Josephson voltage noise source is experimentally demonstrated. Optimising the cryoprobe shielding and filtering of the pulse bias current efficiently reduces additional possible errors from electromagnetic interference and crosstalk. For the first time, AC voltage comparisons between two pulse-driven Josephson voltage standards for a signal frequency range up to 500 kHz have been carried out as part of this work in order to check the system’s amplitude accuracy. High-frequency amplitude deviations due to the output cabling and the pulse bias current are analysed systematically. The measurement results show very good agreement with the model created and are within ±1 μV/V up to 500 kHz for all configurations investigated, once the expected frequency dependence is corrected. Finally, the optimised Josephson voltage noise source generates low-distortion multi-tone waveforms for calibration of the frequency response and investigation of the signal gain linearity of critical noise thermometer components. Two different types of multi-tone waveforms are compared to demonstrate the effect of intermodulation distortion during calibration. A gain linearity of the signal path including a prototype amplifier for the new noise thermometer and an analogue-to-digital-converter is experimentally demonstrated within ±2 μV/V for input-referred noise levels from 9.7 μV to 465 μV. The results of this work prove the suitability and accuracy of the Josephson voltage noise source for the calibration of the new noise thermometer up to 225 kHz. Furthermore, this work has thoroughly extended the understanding of pulse-driven Josephson voltage standards up to 500 kHz. Moreover, the results contribute to the improvement of the future noise thermometer., Berichte aus dem Institut für Elektrische Messtechnik und Grundlagen der Elektrotechnik, vol. 71

The feasibility of 3D-printed molds for complex solid fuel block geometries of hybrid rocket engines is investigated. Additively produced molds offer more degrees of freedom in designing an optimized but easy to manufacture mold. The solid fuel used for this demonstration was hydroxyl-terminated polybutadiene (HTPB). Polyvinyl alcohol (PVA) was chosen as the mold material due to its good dissolving characteristics. It is shown that conventional and complex geometries can be produced reliably with the presented methods. In addition to the manufacturing process, this article presents several engine tests with different fuel grain geometries, including a short overview of the test bed, the engine and first tests.

Real-time spectrum sensing is essential to enable dynamic and rapid spectrum sharing of unused frequencies to cater the substantial demands of new wireless services deploying the existing RF bands. In this paper, we present a novel, real-time spectrum sensing approach for widely used RF signals based on Brillouin-scattering-induced transparency (BIT). A temporal discrimination of multi-channel input frequencies is achieved through the group delay tuning by BIT. By tuning the pump power and frequency, the proposed technique is fully reconfigurable and viable for a broad range of spectrum sensing. Several experimental illustrations of the time domain sensing are presented for two-tone channels with 0.9, 1.8, and 5 GHz frequencies to detect the unused spectrum within 3G, 4G, and 5G signals.

Unmanned aircraft systems (UAS) have rapidly become more common in various applications. At the same time, the need for a safe UAS operation is of great importance to minimize and avoid risks that could arise with the deployment of this technology. With these requirements, UAS regulators in the European Union (EU) are making large efforts to enable a reliable legal framework of conditions for UAS operation to keep up with new capabilities of this technology and to minimize the risk of property damage and, most importantly, human injury. A recent outcome of the mentioned efforts is that new EU drone regulations are into force since 1 January 2021. In this paper we aim to provide a sound overview of recent EU drone regulations and the main changes to the rules since the first wave of regulations adopted in 2017. We highlight how such new rules help or hinder the use of UAS technology and its economic potential in scientific and commercial sectors by providing an exploratory investigation of UAS legal frames in Europe. An example of the impact of legislation on the operation of one particular UAS in Germany is provided, which has been in use since 2013 for atmospheric research.

Kraftstoffverbrauch, Schadstoff- und CO2-Emissionen von Verbrennungsmotoren können mittels Formhonen von Zylinderlaufbahnen reduziert werden, indem durch das Honen beliebiger Freiformen betriebspunktspezifische Zylinderverzüge fertigungstechnisch vorgehalten werden. In der vorliegenden Arbeit wird das Formhonen von modernen, thermisch gespritzten Zylinderlaufbahnen erforscht. Hierzu werden für die einzelnen Prozessschritte die Auswirkungen von Prozessgestaltung, Honleistenanpressdruck und Schneidmittel-spezifikation auf das Bearbeitungsergebnis untersucht. Die Erfassung des ortsaufgelösten Honleistenanpressdrucks erfolgt dabei durch ein eigens entwickeltes Inprozess-Kraftmesssystem, welches zusätzlich Rückschlüsse auf das Werkzeugübertragungsverhalten zulässt. Die Untersuchungen zeigen, dass zu Bearbeitungsbeginn die thermische Spritzschicht durch teils sehr hohe Honleistennormalkräfte derart geschädigt werden kann, dass die gewünschte Solloberfläche nicht mehr herstellbar ist. Durch die entwickelte Formhonstrategie mit zeitlich skalierten Ansteuerwerten für die Piezoaktoren können für die zeitlich und örtlich unterschiedlichen Zeitspanvolumen verbesserte und einheitlichere Oberflächentopografien erzielt werden. Dabei ermöglicht die Inprozess-Messmethodik zur Ermittlung der Honleistennormalkräfte eine optimale Auslegung der Skalierungsschrittweite. Neben dem absoluten Kraftniveau während des Honens kann damit auch erstmalig der zeitliche Verlauf der Honleistennormalkräfte beobachtet werden. Zur weiteren Oberflächenverbesserung erfolgt im Anschluss an die Formhonbearbeitung ein Glätthonprozess mit federnd gelagerten Honleisten. Zusätzlich können durch eine geeignete Schneidmittelauswahl die Anforderungen an die finale Solloberfläche erfüllt sowie wirtschaftliche Werkzeugstandmengen erzielt werden. Darüber hinaus werden beim Formhonen von lastpunktspezifischen Antiverzugskonturen neben der geforderten Oberflächengüte die an die Sollform gestellten Anforderungen hinsichtlich Dynamik, Formausprägung, Zerspanvolumen sowie Fomgenauigkeit erreicht., Form honing of cylinder bores can reduce fuel consumption, pollutants and CO2 emissions of combustion engines by honing random shapes that provide cylinder distortions of specific engine operating points. The form honing of modern, thermal sprayed cylinder bores is developed in this paper. For this, effects of process design, contact pressure of the honing stones and specifications of abrasives onto the machining results will be investigated for each process step. The recording of space-resolved contact pressure of the honing stones is carried out by a self-developed in-process force measurement system that additionally draws conclusions onto the honing tool performance. This study found that partially high contact pressures at the beginning of the honing process may damage the thermal sprayed layers to such an extent that the desired running surface cannot be produced afterwards. The developed form honing process uses temporally scaled control voltage for the piezo actuators. With the help of this strategy it is possible to achieve an improved and more consistent running surface for the temporally and locally different stock removal rates. At the same time the in-process measurement system, developed to determine the normal forces of the honing stones, facilitates an optimised design of the scaling factors. In addition to the absolute force level during the form honing process, the chronological sequence of the contact pressures of the honing stones can be monitored for the first time ever. After form honing a smoothing process that uses spring-loaded honing stones is performed to further improve the running surface. Moreover, suitable abrasives can obtain requirements for the final running surface and generate profitable tool life quantities. On top of that, form honing of operating-point-specific anti-distortion-shapes achieves the requested running surface as well as the required cylinder shape concerning dynamics, shape characteristics, stock removal rates and shape accuracy., Schriftenreihe des Instituts für Werkzeugmaschinen und Fertigungstechnik, vol. 2021

Increasing demand response (DR) from households, industry and tertiary sector may provide substantial flexibility in renewable-based energy systems, but the deployment of DR is currently limited. This study examines the future economic potential DR in the renewable rich northern European region, and also analyses power markets impacts of large-scale DR deployment in the region. For the quantifications, the energy system model BALMOREL is used, modified to include a detailed temporal modelling of available DR potentials. Results show that among the DR options analysed, space heating and water heating provide the highest shares of loads shifted. The overall demand response potential is particularly high in Norway and Sweden, due to wide-spread electric space- and water heating. Low variable costs make these DR applications economically feasible for deployment, despite high supply-side flexibility provided by regulated hydro power. DR may contribute to peak shaving of up to 18.6% of total peak load in 2050. Revenues from DR-application yield very different results depending on techno-economic parameters, potentials and the price volatility in the various analysed market areas. Results show an insignificant change in CO2 emissions between scenarios with and without demand response.

Today, vehicle development is already in a process of substantial transformation. Mobility trends can be derived from global megatrends and have a significant influence on the requirements of the developed vehicles. The sociological, technological, economic, ecological, and political developments can be determined by using the scenario technique. The results are recorded in the form of differently shaped scenarios, however, they are mainly document-based. In order to ensure a holistic approach in the sense of model-based systems engineering and to be able to trace the interrelationships of the fast-changing trends and requirements, it is necessary to implement future scenarios in the system model. For this purpose, a method is proposed that enables the consideration of future scenarios in model-based vehicle development. The procedure of the method is presented, and the location of the future scenarios within the system architectures is named. The method is applied and the resulting system views are derived based on the application example of an autonomous people mover. With the help of the described method, it is possible to show the effects of a change of scenario (e.g., best-case and worst-case) and the connections with the highest level of requirements: stakeholder needs.

Estimating time-frequency domain masks for single-channel speech enhancement using deep learning methods has recently become a popular research field with promising results. In this paper, we propose a novel components loss (CL) for the training of neural networks for mask-based speech enhancement. During the training process, the proposed CL offers separate control over preservation of the speech component quality, suppression of the noise component, and preservation of a naturally sounding residual noise component. We illustrate the potential of the proposed CL by evaluating a standard convolutional neural network (CNN) for mask-based speech enhancement. The new CL is compared to several baseline losses, comprising the conventional mean squared error (MSE) loss w.r.t. speech spectral amplitudes or w.r.t. an ideal-ratio mask, auditory-related loss functions, such as the perceptual evaluation of speech quality (PESQ) loss and the perceptual weighting filter loss, and also the recently proposed SNR loss with two masks. Detailed analysis suggests that the proposed CL obtains a better or at least a more balanced performance across all employed instrumental quality metrics, including SNR improvement, speech component quality, enhanced total speech quality, and particularly also delivers a natural sounding residual noise component. For unseen noise types, we excel even perceptually motivated losses by an about 0.2 points higher PESQ score. The recently proposed so-called SNR loss with two masks not only requires a network with more parameters due to the two decoder heads, but also falls behind on PESQ and POLQA and particularly w.r.t. residual noise quality. Note that the proposed CL shows significantly more 1st ranks among the evaluation metrics than any other baseline. It is easy to implement, and code is provided at https://github.com/ifnspaml/Components-Loss.

Vacuum-based handling, used in many applications and industries, offers great flexibility and fast handling processes. However, due to significant energy conversion losses from electrical energy to the useable suction flow, vacuum-based handling is highly energy-inefficient. In preliminary work, we showed that our grasp optimization method offers the potential to save at least 50% of energy by a targeted placement of individual suction cups on the part to be handled. By considering the leakage between gripper and object, this paper aims to extend the grasp optimization method by predicting the effective compressed air consumption depending on object surface roughness, gripper diameter and gripper count. Through balancing of the target pressure difference and the leakage tolerance in combination with the gripper count and gripper diameter, significant reductions of the compressed air, use and therefore the overall energy consumption, can be achieved. With knowledge about the gripper-specific leakage behavior, in the future it will be straightforward for system integrators to minimize the need for oversizing due to process-related uncertainties and therefore to provide application-specific and energy-optimized handling solutions to their customers.

Anchored Large Woody Debris (LWD) is increasingly being used as one of several nature-based coastal protection strategies along the north-western coasts of Canada and the US. As an alternative to conventional hard armoring (e.g., seawalls), its usage is widely considered to be less harmful to the coastal ecosystem while maintaining the ability to protect the beaches against wave attack and erosion. The effects of seawalls on beaches have been extensively studied, however, the performance and efficacy of LWD and its potential as a suitable alternative to seawalls (and other shoreline protection structures) are still understudied in current research. This paper presents and compares the effects of a conventional vertical seawall with two different LWD structures on beach morphology and wave reflection through large-scale physical modeling in a wave flume at a 1:5 scale. An assessment of techniques used to measure beach morphology and an assessment of model effects were included in the study. It was found that the wave reflection could be reduced by using a single log instead of a wall structure, while changes in the beach morphology response largely depended on the type of the LWD structure. A stacked log wall showed near-identical behavior as a conventional seawall. Visible model effects from the experiments, including the effect of the flume sidewalls on the beach morphology, were quantified and analyzed to inform future research.