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This paper reveals that the standard test procedures for the qualification and verification of traction battery systems are not sufficient in certain cases. In fact, realistic and application-oriented tests on the interaction among the complex battery subsystems are inevitable. To achieve these objectives, a high-performance test bench with the unique selling features of a high voltage/- and current range, extremely low ripple currents, and high dynamics is presented. For the operation of the applied multiphase current-sharing inverter for charging/discharging the device under test (DUT), special control algorithms, especially a current balancing control method, is introduced.
This paper will present different modulation schemes for optimizing the efficiency of low-voltage traction drives.
The converter of the vehicle automatically has to select the most suitable modulation or control scheme depending
on the present operating point in order to maximize the efficiency of the complete drive train. Furthermore, the
functional principles and algorithms of the individual modulation schemes will be presented, as well as the transition
between those schemes. Finally, the performance of the different schemes will be proved by dynamic and
stationary tests through fully automatized measurement analysis.
Dieses Werk zeigt Benchmarking als Analysemethode des Immobilien-Controllings besonders im Kontext der Renditeoptimierung und Kostensenkung.
In der überarbeiteten 3. Auflage wird seine Anwendung in den Disziplinen Investment- und Portfoliomanagement sowie Asset-, Property- und Facility Management sowie die integrale Bedeutung innerhalb des Immobilienlebenszyklus beschrieben. Die erforderlichen Grundlagen, Methoden, Vorgehensweisen, als auch die einzelnen Bausteine des Benchmarkings werden detailliert und anhand einer Vielzahl von Praxisbeispielen erläutert.
Die Entwicklungsmethodik für mechatronische Systeme benötigt eine sehr gute Integrationsfähigkeit der verwendeten (Software-) Werkzeuge für den Systementwurf, den domänenspezifischen Entwurf, sowie für die Systemintegration. Hierzu wurden verschiedene Werkzeuge untersucht, die eine Abbildung des Model Based Systems Engineering (MBSE) ermöglichen. Insbesondere Werkzeugumgebungen für integriertes und föderiertes MBSE wurden untersucht. Ein Hauptaugenmerk wurde auf die Integration der Simulation in Verknüpfung mit SysML oder ähnlichen Modellen gelegt. Zu diesem Zweck wurde ein Referenzsystem mit verschiedenen Werkzeugen virtuell aufgebaut und der Umfang der Werkzeuge bewertet. Zum Aufbau des Referenzsystems wurde grundlegend mit dem RFLP-Ansatz und der FAS-Methode vorgegangen. Ferner wurde untersucht, ob die vorliegenden Methoden ausreichend sind, um MBSE mit den Werkzeugen zu betreiben. Die Arbeit zeigt, dass die Methoden im Umfeld des MBSE noch weiter ausgearbeitet werden müssen.
"Doppelte AfA bei Bebauung eines Ehegattengrundstücks": So ähnlich lauteten die Reaktionen auf ein Urteil des BFH (9.3.16, X R 46/14) zur ertragssteuerlichen Behandlung eines Betriebsgebäudes, das ein Unternehmer auf einem auch dem Nichtunternehmer-Ehegatten gehörenden Grundstück errichtet hatte. Neben dem BFH hat sich auch die Finanzverwaltung ausführlich mit diesem Gestaltungsmodell beschäftigt (BMF 16.12.16, IV C 6 - S 2134/15/10003). In einem Musterfall werden Chancen und Risiken gegeneinander abgewogen und Alternativen vorgestellt.
Cooperative Starting Intention Detection of Cyclists based on Smart Devices and Infrastructure
(2017)
Einsatz derivativer instrumente für die Integration erneuerbarer Energien in bestehende Strommärkte
(2017)
Die aktuellen politischen Maßnahmen zur Integration erneuerbarer Energien in den Strommarkt sind ineffizient und teuer, gleichzeitig schädigen sie den bestehenden Markt. Mittels der Kombi-nation fluktuierender und regelbarer erneuerbarer Energien in Kombikraftwerken und der Ver-marktung der Leistung als Derivat am Terminmarkt kann der Spotmarkt entlastet werden. In der Folge reduziert sich die EEG-Umlage und erneuerbare Energien können als gesicherte Leistung im Markt zur Verfügung gestellt werden. Im folgenden Beitrag soll ein organisatorischer Ansatz für die Integration erneuerbarer Energien in den Strommarkt aufgezeigt werden, der den Ausbau der erneuerbaren Energien unter marktwirt-schaftlichen Aspekten ermöglicht, die Versorgungssicherheit gewährleistet und dem bestehenden Kraftwerkspark einen geordneten Umbau hin zu einem flexiblen System ermöglicht.
(2) (PDF) Einsatz derivativer Instrumente für die Integration erneuerbarer Energien in bestehende Strommärkte. Available from: https://www.researchgate.net/publication/317580615_Einsatz_derivativer_Instrumente_fur_die_Integration_erneuerbarer_Energien_in_bestehende_Strommarkte.
We report on the joining of transparent thermoplastic polymers using infrared femtosecond laser pulses. Due to nonlinear absorption, the developed micro-welding process for cyclo-olefin copolymers does not require any intermediate absorbing layers or any surface pre-processing of the welding partners. In view of an optimized and stable micro-welding process, the influence of the welding speed and focal position on both, the quality and shear force strength are investigated. We highlight that welding seam widths of down to 65 µm are feasible for welding speeds of up to 75 mm/s. However, a variation of the welding speed affects the required focal position for a successful joining process. The shear force strength of the welding seam is determined to 37 MPa, which corresponds to 64% of the shear strength of the bulk material and is not affected by the welding speed.
We report on laser direct generation of 3D-microchannels for microfluidic applications inside PMMA bulk material by focused femtosecond pulses. Inner lying channels with cross sectional areas from 100 µm2 to 4400 µm2 are directly created in the volume of a PMMA substrate. Using the presented process, the channel length is fundamentally unlimited. Here we demonstrate a channel length of 6 meters inside a substrate with dimensions of 20 × 20 × 1.1 mm. The formation of the micro channels is based on nonlinear absorption around the focal volume that triggers a material modification. The modified volume can be selectively opened to form the channel by a subsequent annealing process. The cross section of the channel is strongly influenced by the energy distribution and illumination around the focal volume determined by the optical setup and process design. The 3D channel layout can easily be realized by moving the specimen using 3D motorized stage, allowing freely chosen complex shaped channel architectures. Within a comprehensive parameter study, varying laser power, number of multi-passes, writing speed and writing depths, we identify an optimized process in terms of attainable channel height, width and aspect ratio, as well as process stability and reproducibility. The proof of concept for an application in three dimensional microfluidic systems is provided by florescence microscopy using a dye rhodamine B solution in isopropanol.
In vitro platform for acoustic and electrophysiological investigations of ultrasound stimulation
(2017)
Since the first time discovered that ultrasound can influence neuronal activity - more than half a century ago - a lot of progress has been made in this field. The possibilities of ultrasound for neuromodulation have been demonstrated in many experiments such as in vivo stimulation of rodent brain or of human cochlear, Further, in vitro experiments with hippocampal slices and other cell types have been performed as well.
MEMS-based Micro-Heaters, in combination with thin-film temperature sensors, are often used for providing the necessary amount of thermal energy for sensor-applications. In this work, we propose an integrated micro-heater as actuator for fusion bonding of polymers, which can optimize the production process of electret-based micro-energy-harvesters. By adjusting the design parameters of thermoforming-molds, we can implement thin-film micro-heaters that are capable of generating temperatures of above 300°C for numerous cycles. Utilizing the integrated micro-heater allows local fusion bonding of Fluoroethylenepropylene (Teflon-FEP) foils on a micrometer-scale while reducing unnecessary thermal stress. This is beneficial for the longevity of the micro-energy-harvesters, while simultaneously improving its performance.
Microelectrode arrays serve as an indispensable tool in electro-physiological research to study the electrical activity of neural cells, enabling measurements of single cell as well as network communication analysis. Recent experimental studies have reported that the neuronal geometry has an influence on electrical signaling and extracellular recordings. However, the corresponding mechanisms are not yet fully understood and require further investigation. Allowing systematic parameter studies, computational modeling provides the opportunity to examine the underlying effects that influence extracellular potentials. In this letter, we present an in silico single cell model to analyze the effect of geometrical variability on the extracellular electric potentials. We describe finite element models of a single neuron with varying geometric complexity in three-dimensional space. The electric potential generation of the neuron is modeled using Hodgkin-Huxley equations. The signal propagation is described with electro-quasi-static equations, and results are compared with corresponding cable equation descriptions. Our results show that both the geometric dimensions and the distribution of ion channels of a neuron are critical factors that significantly influence both the amplitude and shape of extracellular potentials.
Spike-contrast: A novel time scale independent and multivariate measure of spike train synchrony
(2017)
Background: Synchrony within neuronal networks is thought to be a fundamental feature of neuronal networks. In order to quantify synchrony between spike trains, various synchrony measures were developed. Most of them are time scale dependent and thus require the setting of an appropriate time scale. Recently, alternative methods have been developed, such as the time scale independent SPIKE-distance by Kreuz et al. New method: In this study, a novel time-scale independent spike train synchrony measure called Spike-contrast is proposed. The algorithm is based on the temporal “contrast” (activity vs. non-activity in certain temporal bins) and not only provides a single synchrony value, but also a synchrony curve as a function of the bin size. Results: For most test data sets synchrony values obtained with Spike-contrast are highly correlated with those of the SPIKE-distance (Spearman correlation value of 0.99). Correlation was lower for data containing multiple time scales (Spearman correlation value of 0.89). When analyzing large sets of data, Spike-contrast performed faster. Comparison of existing method:
Spike-contrast is compared to the SPIKE-distance algorithm. The test data consisted of artificial spike trains with various levels of synchrony, including Poisson spike trains and bursts, spike trains from simulated neuronal Izhikevich networks, and bursts made of smaller bursts (sub-bursts). Conclusions: The high correlation of Spike-contrast with the established SPIKE-distance for most test data, suggests the suitability of the proposed measure. Both measures are complementary as SPIKE-distance provides a synchrony profile over time, whereas Spike-contrast provides a synchrony curve over bin size.
In this work we present a new micro-system-technology based production process for
unipolar ferroelectrets. Theoretical analysis of the influence of the air-gap size on the electric
field distribution as well as on the induced charge on the electrodes shows superior performance
of unipolar piezoelectrets with small air-gaps. For the production of these small air-gaps we
developed a new design using a photoresist thermoforming master, an integrated micro-heater
and shadow masks for metallization. Unipolar piezoelectrets produced with this technology
exhibit increased d33-coefficients compared to designs in previous publications. These
piezoelectrets are highly preferable for energy-harvesting applications, as they promise high
electric power output.
This study analyzes how information influences decision making in escalation of situations. In those situations decision makers follow a losing course of action and invest further resources even when accounting information indicates that the project is performing poorly and should be discontinued. We conducted two experiments with Chinese participants and used a replication of Staw's (1976) often cited case. Our study investigates how different levels of information load influence escalation of commitment of Chinese participants. Contrary to the prior findings in Germany, we find that Chinese decision makers do not escalate when facing different levels of information load. These results, in light of prior studies that find a comparatively strong escalation tendency of Chinese decision makers, are explained along with the limitations and further research. Abstract This study analyzes how information influences decision making in escalation of situations. In those situations decision makers follow a losing course of action and invest further resources even when accounting information indicates that the project is performing poorly and should be discontinued. We conducted two experiments with Chinese participants and used a replication of Staw's (1976) often cited case. Our study investigates how different levels of information load influence escalation of commitment of Chinese participants. Contrary to the prior findings in Germany, we find that Chinese decision makers do not escalate when facing different levels of information load. These results, in light of prior studies that find a comparatively strong escalation tendency of Chinese decision makers, are explained along with limitations and further research.
This study analyzes the renegotiations that take place between institutionalized public–private partnerships (PPPs) and their public clients drawing on survey data on the PPPs of the German Federal Armed Forces. Generally, both the party that initiates such renegotiations and the time at which renegotiations are launched determine the outcome of the PPP’s renegotiated remuneration. This effect is moderated by the degree of contract specificity and by a decrease in demand. Specifically, when the public client initiates the renegotiation of an incomplete contractual agreement due to a decrease in demand, it can successfully reduce the remuneration of the PPP.
The Blessing of Cash
(2017)
The introduction of cashless wage payments and the spread of branch banking in post-war Germany
(2017)
Kosten und Nutzen des Bargelds und unbarer Zahlungsinstrumente : der Nutzen von Bargeld ; Modul 2
(2017)
Influence of sputtering pressure on the nanostructure and the X-ray reflectivity of iridium coatings
(2017)
Reflective mirror coatings made of iridium are used in X-ray telescopes of the Chandra X-ray Observatory (CXO) launched in 1999 by the National Aeronautics and Space Administration (NASA) to investigate astronomical sources at photon energies below 10. keV. These coatings were produced in a DC magnetron sputtering process and have so far proven their suitability for space-based applications. We are considering in the present paper the processing of thin iridium films for lightweight telescopes using the radio frequency magnetron sputtering technique with an oblique angle deposition. The coating development presented here is focused on the influence of total sputtering pressure on film properties as well as on its impact on the mirror's performance. Characterisation methods such as X-ray diffractometry, X-ray reflectometry, atomic force microscopy and transmission electron microscopy have been used. Correlations between morphology, density, surface micro-roughness, crystal structure of the iridium layer and the expected reflectivity of the X-ray mirror are described and discussed.
Future investigations of astronomical X-ray sources require light weight telescope systems with large collecting areas and good angular resolution. The Wolter I type telescope design offers a suitable possibility for obtaining performant X-ray mirrors with high collecting areas. The technology based on replicated slumped glass optics using thin glasses thereby provides the opportunity to fulfil the light weight and mass production requirements. In NASA's telescope NuSTAR this technology has been proven as advantageous compared to previous systems. Coating thin glasses with iridium, gold or platinum enhances the reflectivity of X-ray mirrors.
Vehicle dynamic considerations regarding the safety of lightweight vehicles need to cover different aspects
than those regarding conventional automobiles. New problems and effects require dedicated research and
modified methods. The present contribution discusses these new challenges covering aspects like specific
vehicle design concepts (e.g. three-wheelers) and the significance of human body mass in relation to the
total mass.
Some initial simulation results are presented that were gained with an example design of a three-wheeled
two seater vehicle. The results show that the seating position and number of passengers have a significant
influence on the stability against rollover. Thus they illustrate that the mass of the human body is of
importance for the dynamic behaviour of the overall system.
The article gives a list of further effects like the stiffness and damping properties of the human body and
also the influence of the human as part of the system in terms of control engineering. A strategy is
suggested which combines computer simulation and road tests. This strategy minimizes the need for costly
testbed experiments for optimizing the simulation models. Particularly when simulation is employed in
order to reduce the need for sensors that would require complicated structural modification (e.g. force
sensors in suspension components). Ideally, sensor application can be limited to inertial sensors and other
positioning sensors like GPS.
If a flexible rotor contacts its stator, the nonlinearities induced by
contact may result in a great variety of vibration phenomena. This article
presents experimental results gained at test rigs. Fundamental phenomena are
analyzed and discussed. First, a modular kit for rotordynamic experiments is
described. The kit allows customizing the properties of rotor and stator that
are relevant for the dynamic behavior. The system allows to specify target
values for natural frequencies, modal damping, clearance width, contact fric-
tion and others. Basic congurations based on this kit were used to study the
in
uence of mass, stiness and damping of both rotor and stator, contact fric-
tion and misalignment of the stator on the vibration of the rotor-stator system.
Extensions of the kit allowed the experimental investigation of systems with
a multitude of natural frequencies, highly
exible stators and even drop down
and overload incidents of rotors supported by active magnetic bearings. The
article also analyzes and explains the various vibration phenomena resulting
from contact. In particular, resonance diagrams from run-up and run-down
processes, orbit plots and frequency spectra are utilized to discuss the dynamic
characteristics. The motion types encountered include not only rotor syn-
chronous motions, but also multi frequency motions (forward and backward
whirl), sub- and super-harmonic motions, motions including sidebands as well
as chaotic motions. Emphasis is put on sensitive system parameters and on
existence and stability of the various types of motion.
In Vitro Platform for Acoustic and Electrophysiological Investigations of Ultrasound Neuromodulation
(2017)
The quality of life has increased dramatically over the past decades. Approximately one billion individuals worldwide will be aged 65 years or older by 2030. With the increasing age of human population, prevalence of neurodegenerative ailments, such as Parkinson’s disease or Alzheimer’s disease, increases. Brain pacemakers are proposed to treat their symptoms. They provide the electrical stimulation of neuronal regions of the central or peripheral nervous system. But for the implantation of brain pacemakers, surgery is needed. Those surgical interventions can be avoided by using transcranial stimulation methods such as Transcranial Magnetic Stimulation (TMS). However, magnetic fields lack the possibility of focusing. Ultrasound (US) offers transcranial characteristics as well and allows focusing on a specific target area in the brain. Over 60 years ago, the Hodgkin-Huxley (H-H) model was presented to simulate the electrophysiological activity of neurons but it lacks to describe the impact of mechanical soundwaves on action potentials in a neuron.
Model Based EGR Control
(2017)
Almost stationary control of the correct EGR rate (Exhaust Gas Recirculation) is state of the art. More aggressive emission tests such as WLTP and RDE require a dynamic control of the EGR rate, otherwise a too low EGR rate results in increased NOx emissions, a too high EGR rate in particulate emissions. The difficulty in any EGR control is the missing plant knowledge; the EGR rate is controlled although the present EGR rate is not exactly known. EGR flow sensors are available, but due to additional costs they have not found a broad acceptance. A different approach for high pressure EGR investigated in this paper is a control using a second lambda sensor between EGR and inlet valves. This approach improves the dynamic response, but it might come with costs similar to an EGR flow sensor. Alternatively a model based approach can be used which shows high potential.
Manipulation von Abgaswerten
(2017)
Dieses kleine Buch stellt Hintergründe zum Abgasskandal dar, z. B. welche Schadstoffe kritisch sind, wie Motorsteuergeräte, Abgasrückführung und Abgasnachbehandlung funktionieren, wie Manipulationen auf dem Prüfstand möglich sind, mit welchen Fahrzyklen getestet wird und in welchem rechtlichen und politischen Umfeld dies lange Zeit unbemerkt mit unterschiedlichen Konsequenzen in der EU und den USA geschehen konnte. Es werden Maßnahmen vorgestellt, mit denen Fahrzeuge auch real gesetzliche Grenzwerte einhalten können und wie Manipulationen zukünftig rechtlich und politisch verhindert werden können. Dem Leser werden durch Literaturhinweise zusätzliche Details erschlossen.
Firms experience that an increasingly complex supply base is a costly investment. In order
to keep specialized suppliers but to reduce the effort of managing it, OEMs contract
second-tier firms and direct them to first-tier suppliers. We conduct four embedded case
studies in the international automotive industry to record types and possible motivations
of directed sourcing. Our findings show that directed sourcing triads may be set up to
achieve operational efficiencies but also for strategic reasons such as to gain access to
foreign markets. This research contributes to literature on triadic supply chains in general
and network buyer-supplier relationships specifically.
Ein zentrales Konzept jeder konstruktivistisch geprägten Auffassung von Lernen ist, dass das Vorwissen, die Präkonzepte und ggf. Fehlvorstellungen der Lernenden einen direkten Einfluss auf den Lernprozess haben: sowohl negativ als auch positiv. Speziell für die Informatik gilt, dass Lernende heutzutage von Beginn an in einer Welt aufwachsen, die von informatischen Artefakten und Systemen nahezu vollständig durchdrungen ist. Sie beobachten sie, interagieren mit ihnen und formen so Vorstellungen über ihre Funktionsweisen und Eigenschaften. Sie bilden somit bereits im Alltag und vor dem Beginn jeglicher Schulbildung kohärente Konzeptionen über zentrale Gegenstände und Inhalte der Informatik. Im Rahmen dieses Workshops werden zunächst verschiedene methodische Ansätze und erste Ergebnisse zu Erhebungen solcher Lernervorstellungen vorgestellt. Anschließend sollen diese anhand von drei Leitfragen verglichen und diskutiert werden: Welche Stärken und Schwächen haben die jeweils verwendeten empirischen Methoden bei der Erhebung von Lernervorstellungen in der Informatik? Wie können sie sich ggf. sinnvoll ergänzen? Welche Implikationen haben die erhobenen Vorstellungen für die Unterrichtspraxis?
To handle heterogeneity within students, to foster needed generic
competencies, to motivate them, and to increase their employability, a didactical method to teach and learn programming in non-major degree programs shall be found. Therefore, this paper covers strategies and the theoretical underpinning concerning these four challenges and gives solutions how to cope with them. Finally, Pair Programming is presented as a method that addresses the issues introduced here.
In the field of X-ray astronomy different types of telescope optics based on grazing incidence mirrors can be used. This contribution presents a special design of a Lobster Eye wide-field telescope with mirrors based on flat silicon wafers and the task of coating such mirror substrates with reflective iridium layers.
Indirect glass slumping of grazing incidence mirror segments for lightweight x-ray telescopes
(2017)
The paper provides a description of recent progress in the development of lightweight, precision and highthroughput
grazing-incidence mirrors for X-ray astronomy made of glass. In particular, the indirect slumping
technology under investigation at the Max Planck Institute for Extraterrestrial Physics (MPE) is reviewed and
recent activities are presented together with the research approach. The glass slumping technique foresees
several steps: a thermal forming process using a suitable mould; a re
ective layer application; the alignment
and integration of mirror segments into a supporting structure; and the nal verication of prototype modules
using X-rays. Each step is considered at MPE, with the involvement of partner institutes and universities. The
last year of activities was mainly dedicated to the procurement of new moulds and to the application of Iridium
coating. The main results will be presented.
Future space-based X-ray observatories need to be very lightweight for launcher mass constraints. Therefore they will
use a reduced mirror thickness, which results in the additional requirement of low coating stress to avoid deformation of
the initial precisely shaped mirror substrates. Due to their excellent reflection properties iridium coatings are sometimes
applied for grazing incidence mirrors in astronomical X-ray telescopes. At Aschaffenburg University of Applied
Sciences the coating of thin iridium films by an RF-magnetron sputtering technique is under development. The work is
embedded in collaborations with the Max-Planck-Institute for Extraterrestrial Physics in Germany, the Czech Technical
University in Prague, the Osservatorio Astronomico di Brera in Italy, the German Leibniz Institute for Solid State and
Materials Research in Dresden, and the French Institute Fresnel. Sputtering with different parameters leads to iridium
films with different properties. The current work is focused on the microstructure of the iridium coatings to study the
influence of the substrate and of the argon gas pressure on the thin film growing process. Correlations between coating
density, surface micro-roughness, the crystalline structure of the iridium layers, and the expected reflectivity of the X-ray
mirror as well as coating stress effects are presented and discussed. The final goal of the project is to integrate the
produced prototype mirrors into an X-ray telescope module. On a longer timescale measurements of the mirror modules
optical performance are planned at the X-ray test facility PANTER.
Sun´s ultraviolet radiation is classified into UV-A, UV-B, and UV-C bands. Thereby UV-A passes through Earth´s atmosphere, while UV-B is partially absorbed by ozone. The limitations of the commonly accepted statement, that UV-C is always completely absorbed by Earth´s atmosphere, are discussed critically. Below 200 nm the solar spectrum is strongly absorbed by molecular oxygen. The stratospheric ozone layer has strong absorption between 200 nm and 300 nm. However, the “ozone hole” increases UV-B radiation just below 300 nm and may also open a transmitting atmospheric window for harmful UV-C at the overlap region between oxygen absorption and ozone absorption.
Within the project JEUMICO, an acronym for Joint European
Mirror Competence, the Aschaffenburg University of Applied Sciences and the
Czech Technical University in Prague started a collaboration to develop mirrors
for X-ray telescopes. Corresponding mirror segments use substrates of
at
silicon wafers which are coated with thin iridium lms, as this material is
promising high re
ectivity in the X-ray range of interest. The sputtering parameters
are optimized in the context of the expected re
ectivity of the coated
X-ray mirrors. In near future measurements of the assembled mirror modules
optical performances are planned at an X-ray test facility.
We present optic designs based on biomimetic, namely technical applications of
animal eyes principles (here: Lobster Eyes) for the special application of wide
field X-ray imaging. Thereby we show and discuss some experimental results
and correlate them with simulations. Preliminary results of an ongoing study on
other strange animal mirror eyes with potential scientific and technical
applications are also discussed. Some of them are based on the principle of
multilayer multi-mirror active optics arrangements. The Lobster Eye X-ray optics
needs special reflective coatings for a better performance, which are currently
developed within the Bavarian-Czech cooperation project JEUMICO.
Das Projekt JEUMICO wird vom Projektträger BAYHOST im Rahmen eines
Programms für bilaterale wissenschaftliche Projekte zwischen Tschechien und
Bayern gefördert. Inhaltlich werden von der Hochschule Aschaffenburg und der
Technischen Universität Prag hier gemeinsam Röntgenoptiken für ein geplantes
astronomisches Experiment an Bord einer NASA-Höhenrakete entwickelt.
High angular resolution, large collecting area and reduced weight per unit area are required for astronomical X-ray telescopes of the next generation observatories. New technologies for processing X-ray mirrors are under development to fulfill these needs. One option is to realize a Wolter I type telescope constituted of several hundred nested thin and light-weight X-ray mirror segments. The individual mirror segments need to be coated with an about 100 nm thick film of a high-reflective material to enhance the reflectivity for X-rays. Thereby an accurate shape metrology of the segments is necessary to predict the angular resolution of the astronomical telescope as well as to control the development process of X-ray mirrors. We present the challenges in shape measurements of thin glasses used to control the coating process and first experimental results about the repeatability of the measurements.
PROBLEM TO BE SOLVED: To provide a radiation resistant glass having radiation resistance and high transparency.SOLUTION: There is provided a radiation resistant glass containing, by wt.%, the following components: SiO of 12 to 45, BO of 0 to 4, AlO of 0 to 4, TiO of 0 to 5, PbO of 50 to 82, NaO of 0 to 4, KO of 0 to 8, and at least 3 doping agents selected from a group consisting of CeO, MoO, BiO, WO, AgO, SnO, SbO and AsO where the total of these doping agents are at least at 0.1 wt.% and the weight percentage of AsO is 0 to <0.2%.
In the field of astronomical X-ray telescopes, different types of optics based on grazing incidence mirrors can be used. This contribution describes the special design of a lobster-eye optics in Schmidt's arrangement, which uses dual reflection to increase the collecting area. The individual mirrors of this wide-field telescope are made of at silicon wafers coated with reflecting iridium layers. This iridium coatings have some advantages compared to more common gold layers as is shown in corresponding simulations. The iridium coating process for the X-ray mirrors was developed within a cooperation of the Aschaffenburg University of Applied Sciences and the Czech Technical University in Prague. Different mirror parameters essential for a proper function of the X-ray optics, like the surface microroughness and the problematic of a good adhesion quality of the coatings were studied. After integration of the individual mirrors into the final lobster-eye optics and the corresponding space qualification testing it is planned to fly the telescope in a recently proposed NASA rocket experiment.
X-ray astronomy uses space-based telescopes to overcome the disturbing absorption of the Earth´s atmosphere. The telescope mirrors are operating at grazing incidence angles and are coated with thin metal films of high-Z materials to get sufficient reflectivity for the high-energy radiation to be observed. In addition the optical payload needs to be light-weighted for launcher mass constrains. Within the project JEUMICO, an acronym for “Joint European Mirror Competence”, the Aschaffenburg University of Applied Sciences and the Czech Technical University in Prague started a collaboration to develop mirrors for X-ray telescopes. The X-ray telescopes currently developed within this Bavarian- Czech project are of Lobster eye type optical design. Corresponding mirror segments use substrates of flat silicon wafers which are coated with thin iridium films, as this material is promising high reflectivity in the X-ray range of interest. The deposition of the iridium films is based on a magnetron sputtering process. Sputtering with different parameters, especially by variation of the argon gas pressure, leads to iridium films with different properties. In addition to investigations of the uncoated mirror substrates the achieved surface roughness has been studied. Occasional delamination of the iridium films due to high stress levels is prevented by chromium sublayers. Thereby the sputtering parameters are optimized in the context of the expected reflectivity of the coated X-ray mirrors. In near future measurements of the assembled mirror modules optical performances are planned at an X-ray test facility.
In Software Engineering education didactical foundation is still at its beginnings. In recent years, this topic is put into stronger focus, as Software Engineering becomes more and more important in our everyday life. However, it is hard to teach and learn, because of diverse factors, e.g. the immateriality of the product. Therefore it is significant to improve the learning process on the one hand and to minimise obstacles to learning on the other hand. Other disciplines – with a long historical background in their ”Fachdidaktik” (e.g., biology or chemistry) – have already dealt with one sort of learning barriers; so-called misconceptions. The hurdle that misconceptions create can and will be explained by the constructivist learning theory. This paper covers a research approach to identify, analyse, filter and Cluster misconceptions in Software Engineering.
Vulnerable road users (VRUs, i.e. cyclists and pedestrians) will play an important role in future traffic. To avoid accidents and achieve a highly efficient traffic flow, it is important to detect VRUs and to predict their intentions. In this article a holistic approach for detecting intentions of VRUs by cooperative methods is presented. The intention detection consists of basic movement primitive prediction, e.g. standing, moving, turning, and a forecast of the future trajectory. Vehicles equipped with sensors, data processing systems and communication abilities, referred to as intelligent vehicles, acquire and maintain a local model of their surrounding traffic environment, e.g. crossing cyclists.
Heterogeneous, open sets of agents (cooperating and interacting vehicles, infrastructure, e.g. cameras and laser scanners, and VRUs equipped with smart devices and body-worn sensors) exchange information forming a multi-modal sensor system with the goal to reliably and robustly detect VRUs and their intentions under consideration of real time requirements and uncertainties. The resulting model allows to extend the perceptual horizon of the individual agent beyond their own sensory capabilities, enabling a longer forecast horizon. Concealments, implausibilities and inconsistencies are resolved by the collective intelligence of cooperating agents.
Novel techniques of signal processing and modelling in combination with analytical and learning based approaches of pattern and activity recognition are used for detection, as well as intention prediction of VRUs. Cooperation, by means of probabilistic sensor and knowledge fusion, takes place on the level of perception and intention recognition. Based on the requirements of the cooperative approach for the communication a new strategy for an ad hoc network is proposed. The evaluation is done using real data gathered with a research vehicle, a research intersection with public traffic and mobile devices.
Objective. Spike detection from extracellular recordings is a crucial preprocessing step when analyzing neuronal activity. The decision whether a specific part of the signal is a spike or not is important for any kind of other subsequent preprocessing steps, like spike sorting or burst detection in order to reduce the classification of erroneously identified spikes. Many spike detection algorithms have already been suggested, all working reasonably well whenever the signal-to-noise ratio is large enough. When the noise level is high, however, these algorithms have a poor performance. Approach. In this paper we present two new spike detection algorithms. The first is based on a stationary wavelet energy operator and the second is based on the time-frequency representation of spikes. Both algorithms are more reliable than all of the most commonly used methods. Main results. The performance of the algorithms is confirmed by using simulated data, resembling original data recorded from cortical neurons with multielectrode arrays. In order to demonstrate that the performance of the algorithms is not restricted to only one specific set of data, we also verify the performance using a simulated publicly available data set. We show that both proposed algorithms have the best performance under all tested methods, regardless of the signal-to-noise ratio in both data sets. Significance. This contribution will redound to the benefit of electrophysiological investigations of human cells. Especially the spatial and temporal analysis of neural network communications is improved by using the proposed spike detection algorithms.