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Spatial modulation (SM) is a low-complexity multiple-input/multiple-output transmission technique that combines index modulation and quadrature amplitude modulation for wireless communications. In this work, we consider the problem of link adaption for generalized spatial modulation (GSM) systems that use multiple active transmit antennas simultaneously. Link adaption algorithms require a real-time estimation of the link quality of the time-variant communication channels, e.g., by means of estimating the mutual information. However, determining the mutual information of SM is challenging because no closed-form expressions have been found so far. Recently, multilayer feedforward neural networks were applied to compute the achievable rate of an index modulation link. However, only a small SM system with two transmit and two receive antennas was considered. In this work, we consider a similar approach but investigate larger GSM systems with multiple active antennas. We analyze the portions of mutual information related to antenna selection and the IQ modulation processes, which depend on the GSM variant and the signal constellation.
Durch Beanspruchungen bei der Fertigung oder in der Anwendung können metastabile austenitische Stähle eine Phasenumwandlung von ?- Austenit zu ?‘-Martensit durchlaufen. Verbunden damit sind Eigenschaftsänderungen, welche sich signifikant auf das Werkstoffverhalten unter mechanischer, tribologischer oder korrosiver Belastung auswirken können.
Um möglichen negativen Auswirkungen wie ungewollte Magnetisierbarkeit oder Beeinflussung von Fertigungsparameter sowie Korrosionseigenschaften zu unterbinden muss die martensitische Phase zunächst erfasst und quantifiziert werden.
Für diese Aufgabe stehen neben den bekannten und kostenintensiven Verfahren wie EBSD und XRD für die praxisnahe Anwendung das magneto-induktive Messverfahren und verschiedene Ätzmethoden zur Verfügung.
Anhand von Applikationen aus Anwendung, Fertigung und Forschung werden die Wirkweisen, Vorteile und Grenzen verschiedener Ätzverfahren und dem magneto-induktiv messenden FERITSCOPE® MP30 aufgezeigt. Ebenso werden ergänzende Methoden bzw. Techniken zur Validation der Verfahren diskutiert und erläutert.
Der DEX Deutscher Ethik Index® gibt Auskunft darüber, ob der Erfolg eines Unternehmens auf anständige Weise erreicht wurde. Zielgruppe des veröffentlichten DEX sind alle Anspruchsgruppen (Stakeholder) und die Gesellschaft. Der DEX informiert darüber, ob das Unternehmen einen Mehrwert für alle seine Stakeholder schafft (= Stakeholder Value). Der DEX unterstützt Entscheidungen der Öffentlichkeit, ob einer Organisation aufgrund ihres Beitrags für die Gesellschaft die „License to Operate“ erteilt wird (= Shared Value).
Im Rahmen des KONTEC Kongresses 2021 in Dresden wurden sowohl ein Poster als auch ein Paper des Forschungsprojekts EKont veröffentlicht. Neben der Schilderung des Versuchsaufbaus werden neuartige Schneidprozesse und Abtragsprinzipien vorgestellt. Im Anschluss daran werden vier Prototypen (gleichsinniger Stufenfräser, gegenläufiger Stufenfräser, mittig gegenläufiger Stufenfräser - Getriebe und oszillierender Werkzeugaufsatz) beschrieben.
Entrepreneurial motivations have become a frequently discussed topic in entrepreneurship research. However, few studies investigated entrepreneurs' motivation across gender and different venture types and tend to rely on surveys or case studies. By using a text mining approach, we investigate if there are differences between male and female entrepreneurs' motivation and if female entrepreneurs' motivation differs across different venture types. This text mining approach in combination with a qualitative content analysis was used to examine unique motivational data from 472 entrepreneurial projects from three different entrepreneurship support programs in Norway and Sweden. Findings suggest that motivation of female and male entrepreneurs differ only slightly, while motivation of female entrepreneurs differs according to the different venture types. We thus contribute to a better understanding of entrepreneurial motivation and to a better understanding of why female entrepreneurs start a business. This can, for instance, benefit the improvement of future female entrepreneurship support programs.
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.
This paper presents a generic method to enhance performance and incorporate temporal information for cardiorespiratory-based sleep stage classification with a limited feature set and limited data. The classification algorithm relies on random forests and a feature set extracted from long-time home monitoring for sleep analysis. Employing temporal feature stacking, the system could be significantly improved in terms of Cohen’s κ and accuracy. The detection performance could be improved for three classes of sleep stages (Wake, REM, Non-REM sleep), four classes (Wake, Non-REM-Light sleep, Non-REM Deep sleep, REM sleep), and five classes (Wake, N1, N2, N3/4, REM sleep) from a κ of 0.44 to 0.58, 0.33 to 0.51, and 0.28 to 0.44 respectively by stacking features before and after the epoch to be classified. Further analysis was done for the optimal length and combination method for this stacking approach. Overall, three methods and a variable duration between 30 s and 30 min have been analyzed. Overnight recordings of 36 healthy subjects from the Interdisciplinary Center for Sleep Medicine at Charité-Universitätsmedizin Berlin and Leave-One-Out-Cross-Validation on a patient-level have been used to validate the method.
For some years, universities in countries where the first language is not English choose English as the medium of instruction. In German universities, instruction in German is still the dominant form, which makes university study in Germany less accessible to international students. To attract international students and to improve career prospects for home students, many German universities offer programmes taught in English or in a combination of German and English. It is widely expected that the implementation of EMI-programmes leads to improvements in English language proficiency (ELP). However, it has emerged that substantial gains in ELP in EMI programmes will only occur as the result of content and language integrated learning.
Engineering and management
(2019)
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.
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.
This document presents a new complete standalone system for a recognition of sleep apnea using signals from the pressure sensors placed under the mattress. The developed hardware part of the system is tuned to filter and to amplify the signal. Its software part performs more accurate signal filtering and identification of apnea events. The overall achieved accuracy of the recognition of apnea occurrence is 91%, with the average measured recognition delay of about 15 seconds, which confirms the suitability of the proposed method for future employment. The main aim of the presented approach is the support of the healthcare system with the cost-efficient tool for recognition of sleep apnea in the home environment.
The electrochemical behavior for different surface conditions and different degrees of deformation of metastable austenitic stainless steel AISI 304 UNS S30400 were studied using critical pitting potential and electrochemical noise measurements. The influence on corrosion resistance by using different abrasives (silicon carbide and corundum) for surface finish by grinding is illustrated. For the characterization of local defects and surface topography, scanning electron microscopy (SEM) and tactile measurements were used. An inverse correlation between occurrence of local defects on the surface and critical pitting potential was found by using image processing. Therefore, gray scale values of different surfaces were compared. The influence of mass content of α'-martensite on the corrosion resistance is shown by comparing different qualities of surface finish. For smooth machined surfaces it can be shown that an increasing numbers of strain induced martensite is decreasing the corrosion resistance lightly. For low abrasive machining an inverse correlation between the critical pitting potential and surface roughness is given. However, for higher abrasive machining parameters, this correlation could not be found.
For European space missions the importance of electric propulsion is strongly growing and has recently experienced a real burst in the telecom market. The initial drivers of this development were programs of the European Space Agency and projects of the European national space agencies. In addition, electric propulsion is now on the priority list of European commercial satellite manufacturers. Actual programs target orbit raising and station keeping with full electric propulsion for telecom satellites. European space industry, represented by individual companies, has developed specific and generic solutions for the electronics dedicated to powering and controlling electric propulsion systems. The European Space Agency and the European Commission providing support for enabling technology related to Power Processing Units (PPUs) and increasing competitiveness.
Was in Kommunen im benachbarten Ausland, bspw. der Schweiz, Österreich oder den Niederlanden offenbar seit vielen Jahren Stand der Technik ist, ist auf Deutschlands Kommunalstraßen eine „Sonderbauweise“: Betonfahrbahnen. Obwohl, gerade in den neuen Bundesländern diese Bauweise häufig zum Einsatz kam, wird sie heute auf größeren Flächen wie gesamte Straßenzüge, bspw. in Wohngebieten, kaum noch angewendet (Bild 1). Die Gründe liegen offenbar in den schlechten Erfahrungen hinsichtlich einer komfortablen Nutzungsdauer sowie der Notwendigkeit, einen „leichteren“ Zugriff auf die unter der Straßenoberfläche liegenden Ver- und Entsorgungseinrichtungen zu haben. Infolge vermehrt auftretender Schäden wie Spurrinnen, Verdrückungen und weiteren Schäden werden hochbelastete Verkehrsflächen wie Bushaltestellen, Busspuren und Kreisverkehre immer häufiger anstatt in Asphalt- oder Pflaster in Betonbauweise ausgeführt. Die Gründe für die Vernachlässigung der Betonbauweise im kommunalen Umfeld liegen neben einem geringen Erfahrungsschatz sicherlich auch in einer aufwändigeren Planung, höheren Ausführungskosten, einem komplexeren Einbau, gerade in Zusammenhang mit Einbauten, Instandhaltungsmaßnahmen und Maßnahmen Dritter an den Ver- und Entsorgungseinrichtungen. Offen ist auch der Nachweis, dass die Betonbauweise im Lebenszyklus wirtschaftlicher als beispielsweise die Asphaltbauweise ist. Die Thematik „Einsatz von Betonflächen in Kommunen“ ist sehr umfangreich und weitläufig und lässt sich mit einem Vortrag generell nicht behandeln. Mit nachfolgenden Ausführungen soll demnach grundsätzlich auf die Belange der Planung, dem Bau und der Wirtschaftlichkeit kommunaler Verkehrsflächen in Betonbauweise eingegangen werden. Es können leider nicht alle Besonderheiten und Einzelheiten wie Baustoffe (Glasfaser) Berücksichtigung finden. Ziel des Vortrages ist, generelle Möglichkeiten hinsichtlich dem Einsatz von Betonflächen im kommunalen Bereich aufzuzeigen. Besonderer Dank gilt dem Straßenbauamt Böblingen sowie Herrn Baudirektor Andreas Klein, dessen persönliche Erfahrungen hier einfließen durften.
Standardmäßig werden zur Modellierung magnetischer Systeme für regelungstechnische Anwendungen oder im Bereich der Diagnose und Prognose konzentriert parametrische Modelle verwendet. Falls eine hohe Qualität der Prozessabbildung erforderlich ist, z.B. um Wirbelströme oder Sättigung geeignet zu berücksichtigen, nehmen diese Modelle schnell relativ hohe Ordnungen an. Es ist seit einiger Zeit bekannt, dass verteilparametrische Systeme, die z.B. (Feld-)Diffusionsprozesse beinhalten, durch niederdimensionale Modelle mit nicht ganzzahligen Ableitungen, so genannte fraktionale Modelle, sehr gut abgebildet werden können. Im Bereich der magnetischen Aktuatoren wurden diese vor rund 10 Jahren zum ersten Mal untersucht. Seitdem wird auf diesem Gebiet in verschiedenen Arbeitsgruppen geforscht. Während im Frequenzbereich die Handhabung fraktionaler Systeme einfach ist, sind Anwendungen im Zeitbereich bisher insbesondere bei zeitkritischen Anwendungen kaum anzutreffen. Der Beitrag stellt die prinzipielle Idee dar und zeigt Möglichkeiten zum Einsatz dieser Verfahren im Bereich magnetischer Aktoren auf. In einer konkreten Anwendung wird in Simulation und Experiment demonstriert, wie mit Hilfe dieser Modelle Zustandsschätzung in Magnetaktuatoren erfolgen kann und welche Vorteile sich dadurch ergeben.
Einfluss der Oberfläche
(2018)
Ein neuzeitlicher Pfahlbau
(2016)
This paper compares novel methods to efficiently include input constraints using the nonlinear Model Predictive Path Integral (MPPI) approach. The MPPI algorithm solves stochastic optimal control problems and is based on sampled trajectories. MPPI results from the physical path integral framework. Sample-based algorithms are characterized by the fact that they can be computed in parallel and offer the possibility to handle discontinuous dynamics and cost functions. However, using standard MPPI the input costs in the Lagrange term have to be chosen quadratic. This fact is unfavorable for various real applications. Further, in standard nonlinear model predictive control (NMPC) approaches hard box constraints on the control input trajectory can be treated directly. In this contribution, novel architectures based on integrator action are compared. The investigated input constraint MPPI controllers were tested on an autonomous self-balancing vehicle. Therefore both, simulation and real-world experiments are presented. This paper addresses the question of how the MPPI algorithm can be further developed to consider input box constraints. Videos of the self-balancing vehicle are available at: https: https://tinyurl.com/mvn8j7vf
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.
Effect of cold working on the localized corrosion behavior of CrNi and CrNiMnN metastable austenites
(2015)
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.
In the last decade, both sustainability (Green &
Blue Economies) and business models for sustainability
(BMfS) have increased in importance. Social life cycle
sustainability assessment has not fully achieved goal,
mainly because sustainability‐oriented business is very
complex and dynamic. System Dynamics (SD) is a powerful
methodology and computer simulation modeling technique
for framing, understanding and discussing complex issues
and problems. This paper responds to the urgent need for
a new business model by presenting a concept for dynamic
business modeling for sustainability using system dynamics.
The paper illustrates the key operating principles through
an application from the smartphone industry with help
from STELLA® software for simulation. Simulations
suggest that dynamic business modeling for sustainability
may contribute to sustainable business model research and
practice by introducing a systemic design tool that frames
environmental, social, and economic drivers of value
generation into a dynamic business model causal feedback
structure, therefore overcoming shortcomings of current
business models when applied to complex systems.
Fachvortrag auf dem Swiss Tribology Symposium, 12.11.2019, Hightechzentrum Aargau, Brugg, Schweiz
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.
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.