Hochschulschriftenserver der TH Wildau
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Development of a backward-mode photoacoustic microscope using a Fabry-Pérot sensor
No full textOptical-resolution photoacoustic microscopy (PAM) has been shown to enable the acquisition of high resolution (μm) functional and anatomical images. For backward-mode operation, conventional piezoelectric ultrasound transducers need to be placed far away from the signal source due to their opacity and size. This can result in reduced acoustic sensitivity. Planar Fabry-Perot polymer film interferometer (FPI) sensors have the potential to overcome this limitation since they are transparent to the excitation wavelength, can be placed immediately adjacent to the signal source for high acoustic sensitivity, and offer a broadband frequency response (0 –50 MHz). In this study, we present a high frame rate, backward-mode OR-PAM system based on a planar FPI ultrasound sensor. A ns-pulsed laser provides excitation pulses (<200 nJ, maximum pulse repetition frequency = 200 kHz, 532 nm) to generate photoacoustic waves that are detected using a planar FPI sensor interrogated at 765-781 nm. For backwardmode operation and highest acoustic sensitivity, the excitation and interrogation beams are coaxially aligned and rasterscanned. The optical transfer function of the sensor, the spatial resolution and the detection sensitivity were determined to characterise the set-up. Images of a leaf phantom and first in vivo images of zebrafish larvae were acquired. This approach will enable fast 3D OR-PAM with high resolution and high sensitivity for functional and molecular imaging applications. FPI-based ultrasound detection also has the potential to enable dual-mode optical- and acousticresolution PAM and the integration of photoacoustic imaging with purely optical modalities such as multi-photon microscopy
Prototypal construction of a table robot as a future development and research platform in the area of Ambient Assisted Living and as an alternative for the NAO-Robot
No full textIn dieser Bachelorarbeit wurde ein prototypischer Tischroboter für den Einsatz im Bereich des Ambient Assisted Livings konzeptioniert. Innerhalb eines festgelegten Budgets wurden die technische Umsetzbarkeit und die Eignung des Systems als Alternative zum im Telematik-Studiengang der Technische Hochschule Wildau verwendeten NAO-Roboter untersucht. Dabei wurde bewusst auf die Möglichkeit einer humanoiden Fortbewegung verzichtet.
Das entwickelte Konzept basiert auf den in dieser Arbeit festgelegten Anforderungen an einen Tischroboter. Es umfasst die benötigten Hardwarekomponenten, wobei als Grundlage des Systems ein Jetson Nano Einplatinencomputer von Nvidia verwendet wird. Weiterhin wurde eine Softwarearchitektur erstellt, welche Front-End, Back-End und angeschlossene Hardwarekomponenten miteinander verknüpft. Im Front-End wird das Framework Electron.js verwendet, im Back-End kommt das Robot Operating System (ROS) in Verbindung mit der Key-Value-Datenbank Redis zum Einsatz. Für die Steuerung weiterer angeschlossener Hardwarekomponenten und der Energieversorgung werden Arduino Nano Boards eingesetzt.
Die konzipierte Architektur des Gesamtsystems ist auf eine funktionale Erweiterbarkeit ausgelegt, um für die Erforschung und Realisierung von vielfältigen Anwendungsfällen in Folgeprojekten geeignet zu sein.
In einer anschließenden Testphase wurde ein Prototyp entwickelt, mit dessen Hilfe die konzipierte Systemarchitektur umgesetzt und erfolgreich getestet wurde. Die Ergebnisse dieser Bachelorarbeit können somit als prototypische Grundlage für eine Alternative zum NAO-Roboter, aber auch als technische Basis für die Entwicklung anderer Roboter verwendet werden.This thesis presents the concept for a prototypical table robot for use in the field of Ambient Assisted Living. The technical feasibility, within a given budget, and the suitability of this concept as an alternative to the robot NAO, which is used in the Telematics course of the Technical University of Applied Science Wildau, has been investigated. The aspect of humanoid locomotion was deliberately excluded from the scope of this thesis.
The developed concept is based on a set of requirements for a table robot that are defined as part of this thesis. The concept includes the required hardware components and uses a Jetson Nano single-board computer from Nvidia as core of the system. In addition, a software architecture has been created in order to connect front-end, back-end and hardware components. The front-end uses the Electron.js framework, in the back-end the Robot Operating System (ROS) is used, as well as the key-value-database Redis. To control further hardware and the energy supplement, Arduino Nano Boards are used.
The resulting architecture of the entire system is designed to be functionally extensible. Therefore, it is suitable for the investigation and realization of versatile use cases in future follow up projects.
As part of the following testing phase, a prototype of the system has been developed. The prototype allowed successful realization and testing of the conceptualized architecture. Thus, the results of this thesis can serve both as a prototypical basis for an alternative to the robot NAO, and more broadly also as a technical foundation for the development of other robots
Fiber Optics - From Fundamentals to Industrial Applications
No full textOptical fibers in metrology, telecommunications, sensors, manufacturing, and health science have gained massive research interest. The number of applications is increasing at a fast pace. This book aims to present a collection of recent advances in fiber optics, addressing both fundamental and industrial applications. It covers the current progress and latest breakthroughs in emergent applications of fiber optics. The book includes five chapters on recent developments in optical fiber communications and fiber sensors, as well as the design, simulation, and fabrication of novel fiber concepts
Reorganisation und Optimierung von Prozessen am Beispiel der Verwaltung von Abschlussarbeiten und des Qualitätsmonitorings von Studiengängen
No full textDie internen Abläufe an Hochschulen folgen selten vordefinierten Regeln, sodass bei der Digitalisierung solcher Prozesse Standardlösungen vielfach nicht ausreichen. Für die Abbildung ehemals analoger Prozesse sind individuelle Softwarelösungen unabdingbar. In diesem Kapitel soll am Beispiel ausgewählter hochschulspezifischer Softwareanwendungen der Weg beschrieben werden, wie ein solcher Umbau im Rahmen bestehender Systeme vollzogen werden kann.
Im Fokus dieser Beschreibung stehen Softwareanwendungen, die sowohl die Verwaltungsprozesse rund um die Erstellung von Thesisarbeiten – beginnend mit der Anmeldung bis zur Abgabe der Arbeit, der Durchführung von Abschlussprüfungen bis zur Publikation der Thesisarbeiten – als auch Akkreditierungsprozesse an der TH Wildau unterstützen, mit denen Modulhandbücher und Logbücher erstellt werden, die die Entwicklung von Studiengängen zwischen den Reakkreditierungen transparent nachvollziehbar machen. Ein besonderes Augenmerk wird auf Schnittstellen anderer Hochschulprozesse gelegt.
Diese Anwendungen wurden mit agilen Methoden erstellt. Das Zusammenspiel von agiler Softwareentwicklung und entsprechenden Evaluationsschritten soll zeigen, wie diese Methoden an der Hochschule mit kleinen Teams effektiv eingesetzt werden können, um mit Blick auf die Verbesserung der Qualität und Einheitlichkeit von Studium und Lehre ein bestmögliches Optimierungspotenzial zu erreichen
Limits of Life and the Habitability of Mars: The ESA Space Experiment BIOMEX on the ISS
No full textBIOMEX (BIOlogy and Mars EXperiment) is an ESA/Roscosmos space exposure experiment housed within the exposure facility EXPOSE-R2 outside the Zvezda module on the International Space Station (ISS). The design of the multiuser facility supports—among others—the BIOMEX investigations into the stability and level of degradation of space-exposed biosignatures such as pigments, secondary metabolites, and cell surfaces in contact with a terrestrial and Mars analog mineral environment. In parallel, analysis on the viability of the investigated organisms has provided relevant data for evaluation of the habitability of Mars, for the limits of life, and for the likelihood of an interplanetary transfer of life (theory of lithopanspermia). In this project, lichens, archaea, bacteria, cyanobacteria, snow/permafrost algae, meristematic black fungi, and bryophytes from alpine and polar habitats were embedded, grown, and cultured on a mixture of martian and lunar regolith analogs or other terrestrial minerals. The organisms and regolith analogs and terrestrial mineral mixtures were then exposed to space and to simulated Mars-like conditions by way of the EXPOSE-R2 facility. In this special issue, we present the first set of data obtained in reference to our investigation into the habitability of Mars and limits of life. This project was initiated and implemented by the BIOMEX group, an international and interdisciplinary consortium of 30 institutes in 12 countries on 3 continents. Preflight tests for sample selection, results from ground-based simulation experiments, and the space experiments themselves are presented and include a complete overview of the scientific processes required for this space experiment and postflight analysis. The presented BIOMEX concept could be scaled up to future exposure experiments on the Moon and will serve as a pretest in low Earth orbit
Phase Transitions and Formation of a Monolayer-Type Structure in Thin Oligothiophene Films: Exploration with a Combined In Situ X-ray Diffraction and Electrical Measurements
Get PDFA combination of in situ electrical and grazing-incidence X-ray diffraction (GIXD) is a powerful tool for studies of correlations between the microstructure and charge transport in thin organic films. The information provided by such experimental approach can help optimizing the performance of the films as active layers of organic electronic devices. In this work, such combination of techniques was used to investigate the phase transitions in vacuum-deposited thin films of a common organic semiconductor dihexyl-quarterthiophene (DH4T). A transition from the initial highly crystalline phase to a mesophase was detected upon heating, while only a partial backward transition was observed upon cooling to room temperature. In situ electrical conductivity measurements revealed the impact of both transitions on charge transport. This is partly accounted for by the fact that the initial crystalline phase is characterized by inclination of molecules in the plane perpendicular to the π-π stacking direction, whereas the mesophase is built of molecules tilted in the direction of π-π stacking. Importantly, in addition to the two phases of DH4T characteristic of the bulk, a third interfacial substrate-stabilized monolayer-type phase was observed. The existence of such interfacial structure can have important implications for the charge mobility, being especially favorable for lateral two-dimensional charge transport in the organic field-effect transistors geometry
New Perspectives on PESP: T-Partitions and Separators
No full textIn the planning process of public transportation companies, designing the timetable is among the core planning steps. In particular in the case of periodic (or cyclic) services, the Periodic Event Scheduling Problem (PESP) is well-established to compute high-quality periodic timetables.
We are considering algorithms for computing good solutions and dual bounds for the very basic PESP with no additional extra features as add-ons. The first of these algorithms generalizes several primal heuristics that have been proposed, such as single-node cuts and the modulo network simplex algorithm. We consider partitions of the graph, and identify so-called delay cuts as a structure that allows to generalize several previous heuristics. In particular, when no more improving delay cut can be found, we already know that the other heuristics could not improve either. This heuristic already had been proven to be useful in computational experiments [Ralf Borndörfer et al., 2019], and we locate it in the more general concept of what we denote T-partitions.
With the second of these algorithms we propose to turn a strategy, that has been discussed in the past, upside-down: Instead of gluing together the network line-by-line in a bottom-up way, we develop a divide-and-conquer-like top-down approach to separate the initial problem into two easier subproblems such that the information loss along their cutset edges is as small as possible.
We are aware that there may be PESP instances that do not fit well the separator setting. Yet, on the RxLy-instances of PESPlib in our experimental computations, we come up with good primal solutions and dual bounds. In particular, on the largest instance (R4L4), this new separator approach, which applies a state-of-the-art solver as subroutine, is able to come up with better dual bounds than purely applying this state-of-the-art solver in the very same time
Analysis of Thermomechanical Properties of Selected Class of Recycled Thermoplastic Materials Based on Their Applications
Get PDFPolypropylene and polystyrene are petroleum-based thermoplastics which are commonly used and disposed of in the environment after their service life, leading to environmental degradation. There is a need to recycle polypropylene and polystyrene, but the effect of recycling on thermo-mechanical properties is not well understood. This study aims to determine thermo-mechanical properties of the recycled polypropylene and recycled polystyrene and compare them with corresponding virgin polypropylene and newly produced polystyrene (general purpose polystyrene 1540 and high impact polystyrene 7240). The study was carried out by preparing bar-shaped samples of recycled polypropylene, recycled polystyrene, general purpose polystyrene 1540, and high impact polystyrene 7240 by compression molding using a hot press and thermally characterizing them to determine glass transition temperature and melting temperature using differential scanning calorimetry. The changes in Young’s modulus, tensile strength, hardness, and toughness due to recycling activities were determined at room temperature (24 °C), 40 °C, 60 °C, and 80 °C. The thermo-mechanical properties of recycled polystyrene (PS) were found to be comparable to those of high impact polystyrene (HIPS) 7240. The study revealed that the hardness and toughness for the recycled polymers were higher than those of corresponding virgin polymers. On the other hand, tensile strength and Young's modulus for the recycled polymers were lower than those of the virgin polymers. Understanding the thermo-mechanical properties of the recycled polymers will contribute to more industrial applications hence increase the rate of recycling, resulting in a reduction in environmental pollution
Angewandte Forschung in der Wirtschaftsinformatik 2019 : Tagungsband zur 32. AKWI-Jahrestagung vom 15.09.2019 bis 18.09.2019 an der Fachhochschule für Angewandte Wissenschaften Aachen
No full textTagungsbeiträge aus den Bereichen Projektmanagement, Didaktik in der Wirtschaftsinformatik, IT-Sicherheit, Anwendungsfälle, Reifegradmodelle, Plattformen für Geschäftsprozesse und Prototypen
Vergleichende akustische Untersuchung von Drohnen-Propellern
No full textDie Reduzierung von Fluglärm ist eine der wesentlichen Herausforderungen der Luftfahrtindustrie. Dies betrifft ebenso unbemannte Luftfahrtsysteme, die zukünftig eine signifikante Rolle im alltäglichen Leben spielen werden. In diesem Zusammenhang wurde im Fachgebiet Luftfahrttechnik der TH Wildau das energetische Potential von Winglets an Propellern („Proplets“) untersucht, deren Einsatz sowohl eine Verbesserung der aerodynamischen Effizienz als auch eine Minderung der Geräuschemission versprachen. Daher musste der akustische Einfluss dieser Proplets präzise bestimmt werden.
In diesem Beitrag wird erstmals die Geräuschemission eines mit Proplets ausgerüsteten Propellers mit einem Referenzpropeller verglichen. Beide Prüfstücke sind, abgesehen von den Blattspitzen, identisch. Neben normgerechten, herkömmlichen Messungen der Schallleistungspegel sowie psychoakustischer Eigenschaften werden beide Prüfstücke mit einem Mikrofon-Array („Akustische Kamera“) untersucht, um die Lärmquellen entlang der Propellerblätter zu visualisieren. Hierfür wird erstmals ein virtuell mitrotierendes Array angewendet, um die aero-akustischen Quellen am stehenden Blatt zu identifizieren.The reduction of aircraft noise is one of the major challenges of the aviation industry. This also concerns unmanned aerial vehicles (UAVs), since they will play an increasingly important role in everyday life. In the context of the presented project the energetic potentials of winglets at propeller tips ("proplets") were investigated in order to increase the aerodynamic efficiency and decrease the noise emission of propellers. Therefore it was necessary to determine the acoustic effects of the attached proplets.
This paper compares the noise emission of a reference propeller with a proplet-equipped propeller for the first time. Except for the tips, they were identically designed. The acoustic power level of both propellers was determined and the results are assessed psycho-acoustically. Additionally an examination of the test pieces with a spaced microphone array ("Acoustic Camera") was conducted to visualize the localization of sound sources on the propellers. A rotational beamforming filter was applied to precisely identify the positions of the rotating aero-acoustic sources