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This PhD investigation lies at the intersection of Architecture, Textile Design and Interaction Design and speculates about sustainable forms of future living, focussing on bionic principles to create alternative lightweight building structures with textiles and digital fabrication techniques. In an interdisciplinary, practice- based design approach, informed by radical case studies from the 1960s to 80s on soft architectures like Archigram, Buckminster Fuller, Cedric Price, or Yona Friedman and critical theory on new materialism, (D. Haraway 1997, K. Barad 1998, J. Bennett 2007) sociological, philosophical (B. Latour 2005, G.Deleuze F., Guattari F 1987) and phenomenological thinkers (L. Malafouris 2005, J.Rancière 2004, B. Massumi 2002, N. Bourriaud 2002 , M. Merleau-Ponty 1963) this research investigates the cultural and social rootedness (Verortung) of novel materials and technologies, exploring in between prosthetic relations between the body and the environment.
Engineering and management
(2019)
Low temperature carburizing of a series of austenitic stainless with various combinations of chromium and nickel equivalents was performed. The investigation of the response towards low temperature carburized for three stainless steels with various Cr- and Ni-equivalents showed that the carbon uptake depends significantly on the chemical composition of the base material. The higher carbon content in the expanded austenite layer of specimen 6 (1.4565) and specimen 4 (1.4539/AISI 904L) compared to specimen 2 (1.4404/AISI 316L) is assumed to be mainly related to the difference in the specimens’ chromium content. More chromium leads to more lattice expansion. Along with the higher carbon content, higher hardness values and higher compressive residual stresses in the expanded austenite zone are introduced than for low temperature carburized AISI 316L. The residual stresses obtained from X-ray diffraction lattice strain investigation depend strongly on the chosen X-ray elastic constants. Presently, no values are known for carbon (or nitrogen) stabilized expanded austenite. Nevertheless, first principle elastic constants for γ′&minus Fe4C appear to provide realistic residual stress values. Magnetic force microscopy and measurement with an eddy current probe indicate that austenitic stainless steels can become ferromagnetic upon carburizing, similar for low temperature nitriding. The apparent transition from para- to ferromagnetism cannot be attributed entirely to the interstitially dissolved carbon content in the formed expanded austenite layer but appears to depend also on the metallic composition of the alloy, in particular the Ni content.
We present an innovative decision support system (DSS) for distribution system operators (DSO) based on an artificial neural network (ANN). A trained ANN has the ability to recognize problem patterns and to propose solutions that can be implemented directly in real time grid management. The principle functionality of this ANN based optimizer has been demonstrated by means of a simple virtual electrical grid. For this grid, the trained ANN predicted the solution minimizing the total line power dissipation in 98 percent of the cases considered. In 99 percent of the cases, a valid solution in compliance with the specified operating conditions was found. First ANN tests on a more realistic grid, calibrated with household load measurements, revealed a prediction rate between 88 and 90 percent depending on the optimization criteria. This approach promises a faster, more cost-efficient and potentially secure method to support distribution system operators in grid management.
The reliable supply of energy is an essential prerequisite for the economic success of a country. Questions of sustainability and the replacement of import dependencies require new tasks with new approaches. This contribution provides an overview of dependencies using the example of German electrical power grids integrating renewable energies. Aspects of energy trading and grid stability are brought into connection, stock exchange trading, grid codes and volatility of used primary energies are discussed.
Business coaching is believed to effectively improve survival and success chances of new technology-based firms (NTBFs). However, not much empirical evidence on the support measure's effectiveness is available. Therefore, a pragmatic two-armed Randomized Controlled Trial (RCT) to test the effect of tactical business coaching on NTBF survival capabilities was designed and, for the most part, carried out. However, due to a lower than expected sample size and great attrition between groups, the RCT reveals deviations from the trial design that impede a thorough data assessment. Based on the data given, a first data analysis does not reveal significant differences in survival capability between the two groups. Thus, to provide guidance for future RCTs in business contexts, lessons learned about how to deal with trickle samples and experiment constellations with third parties carrying out the intervention are drawn.
Vortrag und Abstract
A physics lab-setup has been developed for engineering students in their first year at university. The so-called LabTeamCoaching helps to improve general lab skills, such as preparing an experiment, writing a documentation, using graphs and drawing conclusions. By using a flipped classroom approach, students get better involved than in our former physics labs when we applied classical methods. This approach will be described and an overview of our 10 years of experience using this method will be given.
These days, medical applications of shape memory alloys (SMAs) can be found in cardiovascular devices, gastroenterology and urology as well as in the area of orthopedic implants, orthodontic devices and clinical instrumentation. Their functional properties combined with excellent biocompatibility increase the possibility and the performance of minimally invasive surgeries. Overviews of existing applications can be found in [1-2]. Within the medical field, most of the applications with shape memory (SM) material take advantage of the superelasticity of NiTi SMAs. In contradiction to the superelastic or mechanical SM effect, the application described in this study uses the thermal SM effect for a new medical implant. Before explaining the SM driven intramedullary bone nail in detail, a short introduction to the bone elongation technique is given.
The background of this application on based in the medical fact that normally any tissue reacts to an injury with repair and healing processes through multiplication of cells. If after a transverse osteotomy a strain stimulus is activated, for example by tensile stress, this multiplication of cells and new formation of tissue may be continued for any length of time. Due to this mechanism, even considerable loss of bone caused by fractures or congenital defective positions, may be compensated without bone grafts. The technique of callus distraction by means of external fixation or intramedullary nail stimulates the formation of callus in the bone gap. Callus is the repair tissue of the bone generated in the fracture gap in case of bone fracture or osteotomy. The gap to be bridged should not be wider than 1 mm per day [3]. The process starts with the exudation of callus around the ends of the broken bone. At first, callus is more like a fibrous tissue. Later it hardens due to deposition of calcium and eventually it is converted into true bone. Three weeks after severance, the vascular system is formed. An overview of current bone lengthening techniques, also called callus distraction, can be found in [3]. External systems are normally used for the extension of bones, the bone fragments being fixed on rings by wires. The decisive disadvantages of those external systems are primarily the considerable risk of infection due to protruding wires, noticeable discomfort for the patient because of the external rings, a coarse cosmetic result because of scarring, as well as rather long hospitalization.
Therefore, internal bone extension systems are of great interest to orthopedic surgery.
This work introduces new signal constellations based on Eisenstein integers, i.e., the hexagonal lattice. These sets of Eisenstein integers have a cardinality which is an integer power of three. They are proposed as signal constellations for representation in the equivalent complex baseband model, especially for applications like physical-layer network coding or MIMO transmission where the constellation is required to be a subset of a lattice. It is shown that these constellations form additive groups where the addition over the complex plane corresponds to the addition with carry over ternary Galois fields. A ternary set partitioning is derived that enables multilevel coding based on ternary error-correcting codes. In the subsets, this partitioning achieves a gain of 4.77 dB, which results from an increased minimum squared Euclidean distance of the signal points. Furthermore, the constellation-constrained capacities over the AWGN channel and the related level capacities in case of ternary multilevel coding are investigated. Simulation results for multilevel coding based on ternary LDPC codes are presented which show that a performance close to the constellation-constrained capacities can be achieved.
It is well known that signal constellations which are based on a hexagonal grid, so-called Eisenstein constellations, exhibit a performance gain over conventional QAM ones. This benefit is realized by a packing and shaping gain of the Eisenstein (hexagonal) integers in comparison to the Gaussian (complex) integers. Such constellations are especially relevant in transmission schemes that utilize lattice structures, e.g., in MIMO communications. However, for coded modulation, the straightforward approach is to combine Eisenstein constellations with ternary channel codes. In this paper, a multilevel-coding approach is proposed where encoding and multistage decoding can directly be performed with state-of-the-art binary channel codes. An associated mapping and a binary set partitioning are derived. The performance of the proposed approach is contrasted to classical multilevel coding over QAM constellations. To this end, both the single-user AWGN scenario and the (multiuser) MIMO broadcast scenario using lattice-reduction-aided preequalization are considered. Results obtained from numerical simulations with LDPC codes complement the theoretical aspects.
The first part of this work shows the development and application of a new material system using high strength duplex stainless steel wires as net material with environmentally compatible antifouling properties for off-shore fish farm cages. Current net materials from textiles (polyamide) shall be partially replaced by high strength duplex stainless steel in order to have a more environmentally compatible system which meets the more severe mechanical loads (waves, storms, predatores (sharks, seals)). With a new antifouling strategy current issues like reduced ecological damage (e.g. due to copper disposal), lower maintenance costs (e.g. cleaning) and reduced durability shall be resolved.
High strength steel wires are also widely used in geological protection systems, for example rockfall protection or slope stabilisation. Normally hot-dip galvanised carbon steel is used in this case. But in highly corrosive environments like coastal areas, volcanic areas or mines for example, other solutions with a high corrosion resistance and sufficient mechanical properties are necessary. Protection systems made of high strength duplex stainless steel wires enable a significantly longer service life of the portection systems and therefore a higher level of security.
Martensitic stainless steels has a wide use, for example for blades, knifes or cutter. The best corrosion resistance of these materials is in hardened condition. For better mechanical properties a tempering is normally applied to increase the durability. The tempering is also reducing the hardness and finally the corrosion resistance. Austempering is meanly used at low alloyed steels and brings a good compromise between durability, hardness and corrosion resistance. For martensitic stainless steels, austempering is normally not a topic because of the very long tempering times.
This work shows first results of austempering of some standard martensitic stainless steels and the influence to corrosion resistance. For reference, hardened and also hardened and tempered specimens were investigated. The corrosions resistance was investigated by electrochemical methods.
Corporate entrepreneurship (CE) is experiencing continuously increasing interest from scholars and practitioners. One reason for this seems to be rooted in the organizational structures of established companies, which are cumbersome for implementing organizational agility and for developing radical innovations. In view of the advancing digitalization, however, exactly this is required in order to be successful in the long-term. CE is a promising managerial tool that offers a wide range of options to pursue the creation of new businesses and to support the companies' transformation in order to adapt to changes in the environment. Even though CE offers a broad range of opportunities, the effective management is a challenge. One reason for this is the ambiguity when it comes to the differences between the various CE forms and the objectives that can be achieved by those. This study, which is based on 13 in-depth interviews from eight high-tech companies, contributes to a better understanding of CE by offering a first harmonized set of CE objectives that is suitable to compare and differentiate across the different forms. In addition to that, three CE types, offering a new perspective on how to differentiate CE forms, are identified and give implications for a more effective management.
Autism spectrum disorders (ASD) affect a large number of children both in the Russian Federation and in Germany. Early diagnosis is key for these children, because the sooner parents notice such disorders in a child and the rehabilitation and treatment program starts, the higher the likelihood of his social adaptation. The difficulties in raising such a child lie in the complexity of his learning outside of children's groups and the complexity of his medical care. In this regard, the development of digital applications that facilitate medical care and education of such children at home is important and relevant. The purpose of the project is to improve the availability and quality of healthcare and social adaptation at home of children with ASD through the use of digital technologies.
Assistive environments are entering our homes faster than ever. However, there are still various barriers to be broken. One of the crucial points is a personalization of offered services and integration of assistive technologies in common objects and therefore in a regular daily routine. Recognition of sleep patterns for the preliminary sleep study is one of the health services that could be performed in an undisturbing way. This article proposes the hardware system for the measurement of bio-vital signals necessary for initial sleep study in a non-obtrusive way. The first results confirm the potential of measurement of breathing and movement signals with the proposed system.
Magnetic effects on austenitic stainless steels, formed during a low temperature carburizing depending on the alloy composition are discussed in this paper. Samples of different austenitic stainless steel alloys have been subjected to a multiple low-temperature carburization. Layer characteriszation with light microscope and hardness profiles show a growth of the layer thickness. The formation of an expanded austenite layer (lattice expansion) could be detected by X-ray diffraction (XRD). Feritscope was used to determine the magnetizability, whereby not all austenitic alloys form a magnetizability after treatment. Furthermore, test procedures were developed to visualize the magnetizability. For this purpose, magnetic force microscope measurements and investigations with ferrofluid were carried out and a fir tree ferromagnetic layer strucure could be proven.
Fachvortrag auf der 10th International European Stainless Steel Conference and 6th European Duplex Stainless Steel Conference (ESSC & DUPLEX 2019), 30.09. – 02.10.2019, Vienna, Austria
This paper summarizes the trends in metallization and interconnection technology in the eyes of the participants of the 8th Metallization and Interconnection Workshop. Participants were asked in a questionnaire to share their view on the future development of metallization technology, the kind of metal used for front side metallization and the future development of interconnection technology. The continuous improvement of the screen-printing technology is reflected in the high expected percentage share decreasing from 88% in three years to still 70% in ten years. The dominating front side metal in the view of the participants will be silver with an expected percentage share of nearly 70% in 2029. Regarding interconnection technologies, the experts of the workshop expect new technologies to gain significant technology shares faster. Whereas in three years soldering on busbars is expected to dominate with a percentage share of 71% it will drop in ten years to 35% in the eyes of the participants. Multiwire and shingling technologies are seen to have the highest potential with expected percentage shares of 33% (multiwire) and 16% (shingling) in ten years.
The investigation of stress requires to distinguish between stress caused by physical activity and stress that is caused by psychosocial factors. The behaviour of the heart in response to stress and physical activity is very similar in case the set of monitored parameters is reduced to one. Currently, the differentiation remains difficult and methods which only use the heart rate are not able to differentiate between stress and physical activity, without using additional sensor data input. The approach focusses on methods which generate signals providing characteristics that are useful for detecting stress, physical activity, no activity and relaxation.
Die Entstehung von Radsatz-Torsionsschwingungen kann aufgrund der zunehmenden Ausnut- zung des Kraftschlusses im Rad-Schiene-Kontakt nicht vollends verhindert werden. Während analytische Untersuchungen zeigen, dass bei der Überschreitung eines bestimmten Dämp- fungswerts die Entstehung von Radsatz-Torsionsschwingungen vollständig vermieden wird, zeigen Simulationen, dass die Schwingungsamplitude des dynamischen Torsionsmoments in- folge des betragsmäβig sinkenden Kraftschlussgradienten und einer gewissen Antriebsstrang- dämpfung bei höheren Gleitgeschwindigkeiten begrenzt ist. Im Gegensatz zur analytischen Formel (17) ist damit ein maximales, dynamisches Torsionsmoment berechenbar.
Durch eine ganzheitliche Betrachtung des Gesamtsystems, bestehend aus dem Kraftschluss zwischen Rad und Schiene, dem Radsatz inkl. Lagerung, sowie Antriebsstrang können ver- schiedene Einflussfaktoren untersucht werden, die eine Radsatz-Torsionsschwingung beein- flussen. Die damit verbundenen Berechnungsmodelle sind aufgrund der Anzahl von Massen und Freiheitsgraden nicht mehr analytisch lösbar. Durch den Einsatz von Mehrkörperdynamik-Software können die Einflussfaktoren identifiziert und deren Einfluss auf die Torsionsneigung des Systems und das dynamische Torsionsmoment quantifiziert werden.
A significant proportion of road traffic accidents are due to inattentiveness or fatigue at the wheel. Approaches to monitoring the driver's condition range from eye tracking and driving behavior analysis to yawn and blink detection and ECG measurement. This work describes the development of a mobile system for the measurement and processing of ECG data. The aim of the signal processing is to quantify the driver’s fatigue with the heartrate variability (HRV). The work includes the hardware and software design of the sensor. First, the development of low-noise electronics including AD conversion is described. Then the software signal processing with QRS complex detection and plotting front end is explained. The resulting sensor is compact, low-cost and provides a good signal for HRV extraction.
Today, many resource-constrained systems, such as embedded systems, still rely on symmetric cryptography for authentication and digital signatures. Asymmetric cryptography provide a higher security level, but software implementations of public-key algorithms on small embedded systems are extremely slow. Hence, such embedded systems require hardware assistance, i.e. crypto coprocessors optimized for public key operations. Many such coprocessor designs aim on high computational performance. In this work, an area efficient elliptic curve cryptography (ECC) coprocessor is presented for applications in small embedded systems where high performance coprocessors are too costly. We propose a simple control unit with a small instruction set that supports different ECC point multiplication (PM) algorithms. The control unit reduces the logic and number of registers compared with other implementations of ECC point multiplications.
The Lempel-Ziv-Welch (LZW) algorithm is an important dictionary-based data compression approach that is used in many communication and storage systems. The parallel dictionary LZW (PDLZW) algorithm speeds up the LZW encoding by using multiple dictionaries. The PDLZW algorithm applies different dictionaries to store strings of different lengths, where each dictionary stores only strings of the same length. This simplifies the parallel search in the dictionaries for hardware implementations. The compression gain of the PDLZW depends on the partitioning of the address space, i.e. on the sizes of the parallel dictionaries. However, there is no universal partitioning that is optimal for all data sources. This work proposes an address space partitioning technique that optimizes the compression rate of the PDLZW using a Markov model for the data. Numerical results for address spaces with 512, 1024, and 2048 entries demonstrate that the proposed partitioning improves the performance of the PDLZW compared with the original proposal.
The cornerstone of cognitive systems is environment awareness which enables agile and adaptive use of channel resources. Whitespace prediction based on learning the statistics of the wireless traffic has proven to be a powerful tool to achieve such awareness. In this paper, we propose a novel Hidden Markov Model (HMM) based spectrum learning and prediction approach which accurately estimates the exact length of the whitespace in WiFi channels within the shared industrial scientific medical ISM) bands. We show that extending the number of hidden states and formulating the prediction problem as a maximum likelihood (ML) classification leads to a substantial increase in the prediction horizon compared to classical approaches that predict the immediate (short-term) future. We verify the proposed algorithm through simulations which utilize a model for WiFi traffic based on extensive measurement campaigns.
CO2 compensation measures, in particular the compensation of flights, are becoming more and more popular. Carbon offsetting is defined as measures financed by donations that save greenhouse gases previously emitted elsewhere through climate protection projects.
CO2 abatement costs are often low in developing countries. This is why most offset projects are implemented there. Nevertheless, this does not mean that the holiday resort and the project country are in any way related to each other.
By linking carbon offset projects with the destination country, the tourist is able to get an impression of the co-financed project. In case such projects are realized in cooperation with the hotel, the hotel operator obtains a new tourist attraction and can demonstrate its efforts to climate protection in a PR-effective way.
This work proposes a suboptimal detection algorithm for generalized multistream spatial modulation. Many suboptimal detection algorithms for spatial modulation use two-stage detection schemes where the set of active antennas is detected in the first stage and the transmitted symbols in the second stage. For multistream spatial modulation with large signal constellations the second detection step typically dominates the detection complexity. With the proposed detection scheme, the modified Gaussian approximation method is used for detecting the antenna pattern. In order to reduce the complexity for detecting the signal points, we propose a combined equalization and list decoding approach. Simulation results demonstrate that the new algorithm achieves near-maximum-likelihood performance with small list sizes. It significantly reduces the complexity when compared with conventional two-stage detection schemes.
The goal of this paper pretends to show how a bed system with an embedded system with sensor is able to analyze a person’s movement, breathing and recognizing the positions that the subject is lying on the bed during the night without any additional physical contact. The measurements are performed with sensors placed between the mattress and the frame. An Intel Edison board was used as an endpoint that served as a communication node from the mesh network to external service. Two nodes and Intel Edison are attached to the bottom of the bed frame and they are connected to the sensors.
The introduction of multi level cell (MLC) and triple level cell (TLC) technologies reduced the reliability of flash memories significantly compared with single level cell (SLC) flash. The reliability of the flash memory suffers from various errors causes. Program/erase cycles, read disturb, and cell to cell interference impact the threshold voltages. With pre-defined fixed read thresholds a voltage shift increases the bit error rate (BER). This work proposes a read threshold calibration method that aims on minimizing the BER by adapting the read voltages. The adaptation of the read thresholds is based on the number of errors observed in the codeword protecting a small amount of meta-data. Simulations based on flash measurements demonstrate that this method can significantly reduce the BER of TLC memories.
This article describes a research project that aims at investigating individual entrepreneurial founders concerning their shift tendencies of decision-making logics - especially during the respective phases of the venture creating process. Prior studies found that team founders show a hybrid perspective on strategic decision-making. They not only combine causation (planning-based) and effectuation (flexible) logics but also show logic shifts and also re-shifts over time. Due to the fact, that founders' social identity shapes early structuring processes, this article describes the necessity of elimination of in-group influences of multi-founding ventures and focus on individuals in order to make specific assessments on logic shifts and re-shifts. Based on an extensive literature review, a pre-selection-test and a qualitative case study design from the empirical body of the paper. Insofar, this study applies a qualitative design of a process research approach to investigate shifts of decision-making logics of individual founders in new venture creation over time.
Autismus-Spektrum-Störungen (ASD) bei Kindern werden häufig zu spät diagnostiziert und die Begleitung der chronischen Krankheit gestaltet sich schwierig. Der vorgestellte Ansatz erlaubt die Behandlung der Kinder in dem bekannten häuslichen Umfeld und versucht die Beziehungen zwischen Schlaf und Verhalten herauszuarbeiten. Die gewonnenen Erkenntnisse sollen die Lebensqualität der Patienten verbessern und den Eltern Hilfestellung geben. Die notwendige infrastrukturelle Unterstützung wird durch medizinisches Fachpersonal geleistet, das auf einen web-basierten Service zurückgreifen kann, der sämtliche Prozesse (Diagnostik, Datenerfassung, -aufzeichnung und Training etc.) begleitet. Die anonymisierten Daten werden in einem Diagnosesystem zentral abgelegt und können so für zukünftige Behandlungsstrategien nutzbar sein. Die umfassende Lösung setzt auf zentrale Elemente von Smart-Homes und AAL auf.
Das hier vorgestellte Netzoptimierungstool kann dem Verteilnetzbetreiber bei einem Störfall im Netz in Echtzeit eine Lösung zur Steuerung seiner Betriebsmittel vorschlagen. Dadurch kann das bestehende Netz optimal genutzt werden und ein kostenintensiver Netzausbau im Mittel- und Niederspannungsnetz verringert oder sogar verhindert werden. Als Grundlage für den Netzoptimierer dient ein künstliches neuronales Netz (KNN). Zum Training des KNN wurden Störfälle generiert, die auf reellen Erzeugungs- und Lastprofilen aus dem CoSSMic-Projekt basieren [1]. Für jeden Störfall wurde aus allen möglichen und sinnvollen Netzkonfigurationen eine optimierte Netztopologie anhand von Lastflussberechnungen ermittelt. Durch die Variation der Stufenschalter der Transformatoren und der Stellungen aller installierten Schalter im Netz wurde berechnet, wie der Stromfluss gelenkt werden muss, damit keines der Betriebsmittel die zulässigen Belastungsgrenzen mehr überschreitet. Für ein virtuelles Testnetz konnte mit einem trainierten KNN zu 90 Prozent die optimale Lösung des jeweiligen Störfalls erkannt werden. Durch die Anwendung der N-Best Methode konnte die Vorhersagewahrscheinlichkeit auf annähernd 99 Prozent erhöht werden.
We present an alternative approach to grid management in low voltage grids by the use of artificial intelligence. The developed decision support system is based on an artificial neural network (ANN). Due to the fast reaction time of our system, real time grid management will be possible. Remote controllable switches and tap changers in transformer stations are used to actively manage the grid infrastructure. The algorithm can support the distribution system operators to keep the grid in a safe state at any time. Its functionality is demonstrated by a case study using a virtual test grid. The ANN achieves a prediction rate of around 90% for the different grid management strategies. By considering the four most likely solutions proposed by the ANN, the prediction rate increases to 98.8%, with a 0.1 second increase in the running time of the model.
Due to the rising need for palliative care in Russia, it is crucial to provide timely and high-quality solutions for patients, relatives, and caregivers. A methodology for remote monitoring of patients in need of palliative care and the requirements will be developed for a hardware-software complex for remote monitoring of patients' health at home.
Entrepreneurial employees
(2019)
Volatile markets and accelerating innovation cycles progressively force established companies to adopt alternative innovation strategies such as entrepreneurship. Due to the key role entrepreneurial employees play for strengthening the company's abilities for innovation and change, various concepts have emerged like corporate entrepreneurship or intrapreneurship. While the extant literature has increasingly examined only specific issues of entrepreneurial employees, an overall view on it lacks investigation. Therefore, the purpose of this paper is to structurally present current research on entrepreneurial employees by conducting a broad systematic literature review. The resulting research streams contribute to a clearer justification for future research and are a first step towards a comprehensive research view related to intrapreneurship.
Die Studienanfänger in den technischen Studiengängen der Hochschulen für angewandte Wissenschaften haben nicht nur in Mathematik sondern auch in Physik sehr unterschiedliche Vorkenntnisse. Obwohl diese Fächer für das grundlegende Verständnis technischer Vorgänge von großer Bedeutung sind, kann die Ausbildung in diesen Bereichen angesichts der begrenzten dafür im Verlauf des Studiums zur Verfügung stehenden Zeitfenster nicht bei Null anfangen. Für Mathematik wurde daher von der Arbeitsgruppe cosh ein Mindestanforderungskatalog zusammengestellt und 2014 veröffentlicht. Er beschreibt Kenntnisse und Fertigkeiten, die Studienanfänger zur erfolgreichen Aufnahme eines WiMINT-Studiums (Wirtschaft, Mathematik, Informatik, Naturwissenschaft, Technik) an einer Hochschule benötigen. Inzwischen hat sich nun eine Arbeitsgruppe von Physikerinnen und Physikern an Hochschulen in Baden-Württemberg gebildet, deren Ziel es ist, einen analogen Mindestanforderungskatalog für den Bereich Physik zu erstellen. Hier wird der aktuell erreichte Stand der Arbeiten vorgestellt.
Extracting suitable features from acquired data to accurately depict the current health state of a system is crucial in data driven condition monitoring and prediction. Usually, analogue sensor data is sampled at rates far exceeding the Nyquist-rate containing substantial amounts of redundancies and noise, imposing high computational loads due to the subsequent and necessary feature processing chain (generation, dimensionality reduction, rating and selection). To overcome these problems, Compressed Sensing can be used to sample directly to a compressed space, provided the signal at hand and the employed compression/measurement system meet certain criteria. Theory states, that during this compression step enough information is conserved, such that a reconstruction of the original signal is possible with high probability. The proposed approach however does not rely on reconstructed data for condition monitoring purposes, but uses directly the compressed signal representation as feature vector. It is hence assumed that enough information is conveyed by the compression for condition monitoring purposes. To fuse the compressed coefficients into one health index that can be used as input for remaining useful life prediction algorithms and is limited to a reasonable range between 1 and 0, a logistic regression approach is used. Run-to-failure data of three translational electromagnetic actuators is used to demonstrate the health index generation procedure. A comparison to the time domain ground truth signals obtained from Nyquist sampled coil current measurements shows reasonable agreement. I.e. underlying wear-out phenomena can be reproduced by the proposed approach enabling further investigation of the application of prognostic methods.
One important skill for engineers is the ability of optimizing their experiments. On their job they will often spend a lot more time designing and improving an experimental setup compared to running the actual experiment itself. Is it possible to teach this complex task in physics labs? A method for reaching this goal is proposed an example is given and discussed.
The exposure to the light has a great influence on human beings in their everyday life. Various lighting sources produce light that reaches the human eye and influences a rhythmic release of melatonin hormone, that is a sleep promoting factor.
Since the development of new technologies provides more control over illuminance, this work uses an IoT based lighting system to set up dim and bright scenarios. A small study has been performed on the influence of illuminance on sleep latency. The system consists of different light bulbs, sensors and a central bridge which are interconnected like a mesh network. Also, a mobile app has been developed, that allows to adjust the lighting in various rooms. With the help of a ferro-electret sensor, like applied in sleep monitoring systems, a subject’s sleep was monitored. The sensor is placed below the mattress and it collects data, which is stored and processed in a cloud or in other alternative locations.
The research was conducted on healthy young subjects after being previously exposed to the preconfigured illuminance for at least three hours before bedtime. The results indicate correlation between sleep onset latency and exposure to different illuminance before bedtime. In a dimmed environment, the subject fell asleep in average 28% faster compared to the brighter environment.
Pitting susceptibility of metastable austenitic stainless steels as a function of surface conditions
(2019)
The influence of surface roughness and local defects on pitting susceptibility of type 304 (UNS S30400) and type 301 (UNS S30100) in chloride solution were investigated. Because the mechanical properties can be regarded as decisive for the achieved surface quality, different properties of the base material were obtained by cold rolling the metastable austenites. This was done before the surfaces were finished. Therefor the surfaces were treated by different grinding parameters to generate different surface conditions and different defects. As a reference, different standardised surface finishes were used.
By using and comparing different methods for the characterization of surface roughness and surface texture, it is possible to find a relationship between the quantity and characteristics of local defects on the one hand and pitting susceptibility on the other hand. For the machining parameters used, a ranking of the influencing factors on the corrosion resistance achieved could be determined.
The automated application of software-based solutions for estimating the pitting susceptibility of machined surfaces and components will be discussed using concrete examples.
Pitting susceptibility of metastable austenitic stainless steels as a function of surface conditions
(2019)
Fachvortrag auf der 10th International European Stainless Steel Conference and 6th European Duplex Stainless Steel Conference (ESSC & DUPLEX 2019), 30.09. – 02.10.2019, Vienna, Austria
Fachvortrag auf dem Swiss Tribology Symposium, 12.11.2019, Hightechzentrum Aargau, Brugg, Schweiz
Corporate Entrepreneurship (CE) became the new paradigm for organizations to cope with the accelerated development of innovations. Therefore, especially established organizations increasingly implement CE activities, even in combination. Scholars point out that a coordinated portfolio of CE activities could yield synergies and thus higher value for the organization and further call for more scientific examinations. This literature review aims to better the understanding of the combined and coordinated use of CE activities as well as about resulting synergies. Results show that there are only very few studies that addressed a combination and/or coordination of CE activities with respect to the creation of additional value, however, without empirical analyses. Yet, five categories of direct and indirect synergies could be derived. Discussing the results as well as the heterogenous use of terminology and concepts, this paper concludes with a research agenda for future analyses.
Fatigue and drowsiness are responsible for a significant percentage of road traffic accidents. There are several approaches to monitor the driver’s drowsiness, ranging from the driver’s steering behavior to analysis of the driver, e.g. eye tracking, blinking, yawning or electrocardiogram (ECG). This paper describes the development of a low-cost ECG sensor to derive heart rate variability (HRV) data for the drowsiness detection. The work includes the hardware and the software design. The hardware has been implemented on a printed circuit board (PCB) designed so that the board can be used as an extension shield for an Arduino. The PCB contains a double, inverted ECG channel including low-pass filtering and provides two analog outputs to the Arduino, that combined them and performs the analog-to-digital conversion. The digital ECG signal is transferred to an NVidia embedded PC where the processing takes place, including QRS-complex, heart rate and HRV detection as well as visualization features. The compact resulting sensor provides good results in the extraction of the main ECG parameters. The sensor is being used in a larger frame, where facial-recognition-based drowsiness detection is combined with ECG-based detection to improve the recognition rate under unfavorable light or occlusion conditions.
Why does a teacher use drama elements in her language classes? This article critically reflects on the author's experiences with employing drama elements in a compulsory class of German as a Foreign Language at college level. Motives for using drama are discussed, with regard to possible positive effects for the teacher-such as rapport with learners and personal confidence-and potential benefits for the language learners-such as promoting vocabulary and grammar learning, fostering oral skills and increasing motivation. After that the drama activities used in class are briefly described. However, two years of experimentation have also shown up a number of problems with implementing drama elements in class and still leave questions open, requiring further iterations of the drama-based approach in this context. The paper was developed from a talk given at the Drama in Education Days in Konstanz 2018.
This document presents an algorithm for a non-obtrusive recognition of Sleep/Wake states using signals derived from ECG, respiration, and body movement captured while lying in a bed. As a core mathematical base of system data analytics, multinomial logistic regression techniques were chosen. Derived parameters of the three signals are used as the input for the proposed method. The overall achieved accuracy rate is 84% for Wake/Sleep stages, with Cohen’s kappa value 0.46. The presented algorithm should support experts in analyzing sleep quality in more detail. The results confirm the potential of this method and disclose several ways for its improvement.
Generative Design Software - How does digitalization change the professional profile of architects
(2019)
Abstract, Poster und Vortrag
The computational complexity of the optimal maximum likelihood (ML) detector for spatial modulation increases rapidly as more transmit antennas or larger modulation orders are employed. Hence, ML detection may be infeasible for higher bit rates. This work proposes an improved suboptimal detection algorithm based on the Gaussian approximation method. It is demonstrated that the new method is closely related to the previously published signal vector based detection and the modified maximum ratio combiner, but can improve the detection performance compared to these methods. Furthermore, the performance of different signal constellations with suboptimal detection is investigated. Simulation results indicate that the performance loss compared to ML detection depends heavily on the signal constellation, where the recently proposed Eisenstein integer constellations are beneficial compared to classical QAM or PSK constellations.
Error correction coding (ECC) for optical communication and persistent storage systems require high rate codes that enable high data throughput and low residual errors. Recently, different concatenated coding schemes were proposed that are based on binary Bose-Chaudhuri-Hocquenghem (BCH) codes that have low error correcting capabilities. Commonly, hardware implementations for BCH decoding are based on the Berlekamp-Massey algorithm (BMA). However, for single, double, and triple error correcting BCH codes, Peterson's algorithm can be more efficient than the BMA. The known hardware architectures of Peterson's algorithm require Galois field inversion. This inversion dominates the hardware complexity and limits the decoding speed. This work proposes an inversion-less version of Peterson's algorithm. Moreover, a decoding architecture is presented that is faster than decoders that employ inversion or the fully parallel BMA at a comparable circuit size.
The Industrial Internet of Things (IIoT) will leverage on wireless network technologies to integrate in a seamless manner Cyber-Physical Systems into existing information systems. In this context, the 6TiSCH architecture, proposed by IETF, represents the current leading standardization effort to enable timed and reliable data communication within IPv6 networks for industrial applications. In wireless networks, Link Quality Estimation (LQE) is a crucial task to select the best routes for data forwarding, regardless of unpredictable time varying conditions. Although, many solutions for LQE have been proposed in literature, the majority of them are not designed specifically for 6TiSCH networks. In this paper, we analyze the performance of existing LQE strategies on 6TiSCH networks.
First, we run a set of simulations to measure the performance of one existing LQE strategy in 6TiSCH. Our simulations show that such strategy can result in measurements with low accuracy due to the 6TiSCH default timeslot allocation strategy. Consequently, we propose an extension of the 6TiSCH Minimal Configuration that allocates specific timeslots for the transmission of probing messages to mitigate the problem. The proposed methodology is demonstrated to effectively reduce the LQE error.
Flooded Edge Gateways
(2019)
Increasing numbers of internet-compatible devices, in particular in the context of IoT, usually cause increasing amounts of data. The processing and analysis of a continuously growing amount of data in real-time by means of cloud platforms cannot be guaranteed anymore. Approaches of Edge Computing decentralize parts of the data analysis logics towards the data sources in order to control the data transfer rate to the cloud through pre-processing with predefined quality-of-service parameters. In this paper, we present a solution for preventing overloaded gateways by optimizing the transfer of IoT data through a combination of Complex Event Processing and Machine Learning. The presented solution is completely based on open-source technologies and can therefore also be used in smaller companies.
This paper presents a new likelihood-based partitioning method of the measurement set for the extended object probability hypothesis density (PHD) filter framework. Recent work has mostly relied on heuristic partitioning methods that cluster the measurement data based on a distance measure between the single measurements. This can lead to poor filter performance if the tracked extended objects are closely spaced. The proposed method called Stochastic Partitioning (StP) is based on sampling methods and was inspired by a former work of Granström et. al. In this work, the StP method is applied to a Gaussian inverse Wishart (GIW) PHD filter and compared to a second filter implementation that uses the heuristic Distance Partitioning (DP) method. The performance is evaluated in Monte Carlo simulations in a scenario where two objects approach each other. It is shown that the sampling based StP method leads to an improved filter performance compared to DP.
At the University of Applied Sciences Konstanz, Germany, a modern electronically controlled dynamometer and several cars are available for tests. Numerous studies have been carried out, and the latest results will be presented. The paper is intended to explain different tests under load. One focus is the driving cycle WLTC (Worldwide harmonized Light vehicles Test Cycle) and the requirements for the proper conduct of investigation with this driving cycle. Two and three wheelers have a great importance for mobility in various Asian countries. But also in other countries, this segment is very important for the so-called First or Last Mile Vehicles. Because of this, a short explanation of the driving cycle WMTC (Worldwide harmonized Motorcycle Emissions Certification/Test Procedure) is given. The various possibilities for the operation of the dynamometer and for carrying out various experiments are shown.
Other important figures that can be determined on a dynamometer are the wheel power, the power losses and eventually the engine performance. With the brake specific torque, the traction force at the propelled wheels, the maximum acceleration or maximum gradeability of a car can be determined.
As well the slippage related to load can be measured on the dynamometer. The dynamic wheel radius of the driven wheels has a significant influence on the slippage. Because of the temperature increase of the tires during the tests the tire pressure increases. A rise of tire temperature, tire pressure, and wheel speed results in an increase of the dynamic wheel radius and slippage. Equations for the determination of the dynamic wheel radius are presented.
Flatness-based feed-forward control of solenoid actuators is considered. For precise motion planning and accurate steering of conventional solenoids, eddy currents cannot be neglected. The system of ordinary differential equations including eddy currents, that describes the nonlinear dynamics of such actuators, is not differentially flat. Thus, a distributed parameter approach based on a diffusion equation is considered, that enables the parametrization of the eddy current by the armature position and its time derivatives. In order to design the feedforward control, the distributed parameter model of the eddy current subsystem is combined with a typical nonlinear lumped parameter model for the electrical and mechanical subsystems of the solenoid. The control design and its application are illustrated by numerical and practical results for an industrial solenoid actuator.
Ziel der Masterarbeit war es, die Feuchtigkeitseigenschaften von Estrichen bei unterschiedlichen Klimaten mithilfe von Sorptionsisothermen zu charakterisieren. Die wenigen Literaturangaben zu Sorptionsisothermen von mineralischen Estrichen beziehen sich im Wesentlichen auf Calciumsulfatestriche und genormte Zementestriche (ohne dass die Zementart: Portlandzemente, Hochofenzemente bzw. CEM I, CEM II, CEM III etc. unterschieden werden) und i.d.R. nur auf eine Lufttemperatur (= 20 Grad C). Anliegen der Arbeit war es, zusätzlich die seit ca. 20 Jahren marktüblichen ternären Schnellzemente mit zu untersuchen und die baupraktisch interessanten Temperaturen von 15 Grad C und 25 Grad C einzubeziehen. Ebenso wurden die Auswirkungen der Klimabedingung auf der Baustelle (Jahreszeit, Luftfeuchtigkeit, Temperatur) auf den Hydratationsvorgang der Estriche untersucht. Dabei wurden jeweils nicht nur ein Vertreter der verschiedenen Bindemittelsysteme, sondern mindestens zwei verschiedene Estriche unterschiedlicher Hersteller mit einbezogen. In Kombination mit den Ergebnissen der Gefügeuntersuchungen (u. a. Hg-Porosametrie) wird belegt, weshalb sich die zement- und schnellzementgebundenen Estriche vollkommen anders verhalten als die calciumsulfatgebundenen Estriche. Dieses unterschiedliche Verhalten ist auch einer der Gründe, warum Estriche mit der KRL-Methode in Bezug auf ihren Feuchtegehalt nicht bewertet werden können. Aus diesem Grund folgt ein Vergleich der Materialfeuchtemessungen "KRL-Methode" mit der handwerksüblichen und seit Jahrzehnten in der Praxis bewährten "CM-Methode".
Summary of the 8th Workshop on Metallization and Interconnection for Crystalline Silicon Solar Cells
(2019)
This article gives a summary of the 8th Metallization and Interconnection workshop and attempts to place each contribution in the appropriate context. The field of metallization and interconnection continues to progress at a very fast pace. Several printing techniques can now achieve linewidths below 20 μm. Screen printing is more than ever the dominating metallization technology in the industry, with finger widths of 45 μm in routine mass production and values below 20 μm in the lab. Plating technology is also being improved, particularly through the development of lower cost patterning techniques. Interconnection technology is changing fast, with introduction in mass production of multiwire and shingled cells technologies. New models and characterization techniques are being introduced to study and understand in detail these new interconnection technologies.
This paper presents the integration of a spline based extension model into a probability hypothesis density (PHD) filter for extended targets. Using this filter the position and extension of each object as well as the number of present objects can jointly be estimated. Therefore, the spline extension model and the PHD filter are addressed and merged in a Gaussian mixture (GM) implementation. Simulation results using artificial laser measurements are used to evaluate the performance of the presented filter. Finally, the results are illustrated and discussed.
Dramapädagogik-Tage 2018
(2019)
Der Tagungsband zur 4. Konferenz zu Drama und Theater im Fremd- und Zweitsprachenunterricht versammelt Tagungsbeiträge aus den Bereichen Grundlagen, Forschung und Praxis. Die Beiträge reichen von Begriffsklärungen zur Dramapädagogik über Skizzen aktueller Forschungprojekte hin zu Praxisbeiträgen zu den Themen Process Drama und interkulturelles Lernen, Körpersprache und Fremdsprachenlernen, Fremdsprachenlernen mit Gedichten, reflektiver Praxis, Drama Grammatik und performativer Literatur- und Kulturdidaktik.
Fast and reliable acquisition of truth data for document analysis using cyclic suggest algorithms
(2019)
In document analysis the availability of ground truth data plays a crucial role for the success of a project. This is even more true at the rise of new deep learning methods which heavily rely on the availability of training data. But even for traditional, hand crafted algorithms that are not trained on data, reliable test data is important for the improvement and evaluation of the methods. Because ground truth acquisition is expensive and time consuming, semi-automatic methods are introduced which make use of suggestions coming from document analysis systems. The interaction between the human operator and the automatic analysis algorithms is the key to speed up the process while improving the quality of the data. The final confirmation of data may always be done by the human operator. This paper demonstrates a use case for acquisition of truth data in a mail processing system. It shows why a new, extended view on truth data is necessary in development and engineering of such systems. An overview over the tool and the data handling is given, the advantages in the workflow are shown, and consequences for the construction of analysis algorithms are discussed. It can be shown that the interplay between suggest algorithms and human operator leads to very fast truth data capturing. The surprising finding is the fact that if multiple suggest algorithms circularly depend on data, they are especially effective in terms of speed and accuracy.
Some 165 global experts and specialists from industry and academic institutes met at the 8th Metallization & Interconnection Workshop (MIW2019) that took place from 13 to 14 May 2019 in Konstanz, Germany. Participants from 19 countries debated results of 28 oral and 11 poster presentations.
All presentations are available on www.metallizationworkshop.info as pdf documents. As in previous editions, lots of room was available for discussions and networking during the two-days program which included panel and market-place discussions as well as social events (reception, workshop dinner).
These proceedings contain: a summary of the oral and poster presentations, the results of the survey conducted during the workshop, and peer-reviewed papers based on workshop contributions.