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Quantifying the spectrum occupancy in an outdoor 5 GHz WiFi network with directional antennas
(2018)
WiFi-based Long Distance networks are seen as a promising alternative for bringing broadband connectivity to rural areas. A key factor for the profitability of these networks is using license free bands. This work quantifies the current spectrum occupancy in our testbed, which covers rural and urban areas alike. The data mining is conducted on the same WiFi card and in parallel with an operational network. The presented evaluations reveal tendencies for various aspects: occupancy compared to population density, occupancy fluctuations, (joint)-vacant channels, the mean channel vacant duration, different approaches to model/forecast occupancy, and correlations among related interfaces.
More and more low-power wide-area networks (LPWANs) are being deployed and planning the gateway locations plays a significant role for the network range, performance and profitability. We choose LoRa as one LPWAN technology and evaluated the accuracy of the Received Signal Strength Indication (RSSI) of different chipsets in a laboratory environment. The results show the chipsets report significantly different RSSI. To estimate the range of a LPWAN beforehand, path loss models have been proposed. Compared to previous work, we evaluated the Longley-Rice Irregular Terrain Model which makes use of real-world elevation data to predict the path loss. To verify the results of that prediction, an extensive measurements campaign in a semi-urban area in Germany has been conducted. The results show that terrain data can increase the prediction accuracy.
The use of wearable devices or “wearables” in the physical activity domain has been increasing in the last years. These devices are used as training tools providing the user with detailed information about individual physiological responses and feedback to the physical training process. Advantages in sensor technology, miniaturization, energy consumption and processing power increased the usability of these wearables. Furthermore, available sensor technologies must be reliable, valid, and usable. Considering the variety of the existing sensors not all of them are suitable to be integrated in wearables. The application and development of wearables has to consider the characteristics of the physical training process to improve the effectiveness and efficiency as training tools. During physical training, it is essential to elicit individual optimal strain to evoke the desired adjustments to training. One important goal is to neither overstrain nor under challenge the user. Many wearables use heart rate as indicator for this individual strain. However, due to a variety of internal and external influencing factors, heart rate kinetics are highly variable making it difficult to control the stress eliciting individually optimal strain. For optimal training control it is essential to model and predict individual responses and adapt the external stress if necessary. Basis for this modeling is the valid and reliable recording of these individual responses. Depending on the heart rate kinetics and the obtained physiological data, different models and techniques are available that can be used for strain or training control. Aim of this review is to give an overview of measurement, prediction, and control of individual heart rate responses. Therefore, available sensor technologies measuring the individual heart rate responses are analyzed and approaches to model and predict these individual responses discussed. Additionally, the feasibility for wearables is analyzed.
Design optimization techniques are often used at the beginning of the design process to explore the space of possible designs. In these domains illumination algorithms, such as MAP-Elites, are promising alternatives to classic optimization algorithms because they produce diverse, high-quality solutions in a single run, instead of only a single near-optimal solution. Unfortunately, these algorithms currently require a large number of function evaluations, limiting their applicability. In this article we introduce a new illumination algorithm, Surrogate-Assisted Illumination (SAIL), that leverages surrogate modeling techniques to create a map of the design space according to user-defined features while minimizing the number of fitness evaluations. On a two-dimensional airfoil optimization problem SAIL produces hundreds of diverse but high-performing designs with several orders of magnitude fewer evaluations than MAP-Elites or CMA-ES. We demonstrate that SAIL is also capable of producing maps of high-performing designs in realistic three-dimensional aerodynamic tasks with an accurate flow simulation. Data-efficient design exploration with SAIL can help designers understand what is possible, beyond what is optimal, by considering more than pure objective-based optimization.
Telecollaborating and communicating in online contexts using English as a Lingua Franca (ELF) requires students to develop multiple literacies in addition to foreign language skills and intercultural communicative competence. This chapter looks at the intersection of technology and teaching ELF, examining mutual contributions of technologies, more specifically Web 2.0, and ELF to each other, and the challenges in designing and implementing collaboration projects across cultures. Moreover, it looks at how the development of digital competencies in ELF (DELF) can be enhanced through the implementation of Web 2.0 mediated intercultural dialogues. The detail of the research design including internet tools used, participants and tasks are also discussed. Data analysis points to a positive attitude towards telecollaboration, also providing confirmation of some of the problems identified in theoretical framework, such as different levels of personal engagement.
In Form der Nachhaltigkeitsberichterstattung werden erstmals sämtliche darauf bezogenen Daten im Unternehmen zusammengestellt und zu Indikatoren aggregiert. Im vorliegenden Beitrag wird überprüft, inwieweit dieser Datenpool für die Produktionsplanung und -Steuerung (PPS) genutzt werden kann. Dazu werden die Berichterstattungsstandards GRI und SASB herangezogen. Die Qualität der Nachhaltigkeitsindikatoren wird anhand der Kriterien Fehlerfreiheit, Aktualität, Relevanz und Angemessener Umfang hinterfragt. Der Lösungsansatz besteht zunächst darin, die für die Nachhaltigkeitsindikatoren aggregierten Daten wieder in ihre Komponenten zu separieren. Bei Daten ohne klaren Bezug zum Produktionsprozess (z.B. gemischte Abfallsammelbehälter) liefert das Erfahrungswissen der Mitarbeiter vor Ort die Basis für einen weiteren Regelkreis, der als Kontinuierlicher Verbesserungsprozess (KVP bzw. Kaizen) innerhalb der Produktion und Montage auf gebaut werden kann. Die Langform des Beitrags wurde online auf ERP-Management.de veröffentlicht.
BWL kompakt für Dummies
(2018)
"BWL kompakt für Dummies" bietet Ihnen eine verständliche Einführung in die Betriebswirtschaftslehre, egal ob Sie sie für die Aus- oder Weiterbildung brauchen oder sich einfach schlau machen wollen. Tobias Amely stellt Ihnen die wesentlichen Elemente und Grundbegriffe der Betriebswirtschaftslehre vor und zeigt die Bezüge zur Unternehmenspraxis auf: Materialwirtschaft, Leistungsbereitstellung und Produktion, Marketing, Investition und Finanzierung, Unternehmensorganisation und -führung, Rechnungswesen und Controlling.
BWL-Formeln für Dummies
(2018)
Können Sie sich auch Formeln so schlecht merken? Das ist mit diesem handlichen Nachschlagewerk auch gar nicht mehr nötig! Der Autor des Bestsellers "BWL für Dummies" Tobias Amely hat für Sie die wichtigsten BWL-Formeln zusammengestellt. Zu jeder Formel finden Sie auch gleich ein anschauliches Beispiel, wie sie eingesetzt wird und eine Erklärung, wofür man sie eigentlich braucht. "BWL-Formeln für Dummies" ist also viel mehr als eine reine Auflistung von Formeln.
Shared Autonomous Vehicles: Potentials for a Sustainable Mobility and Risks of Unintended Effects
(2018)
Automated and connected cars could significantly reduce congestion and emissions through a more efficient flow of traffic and a reduction in the number of vehicles. An increase in demand for driving with autonomous vehicles is also conceivable due to higher comfort and improved quality of time using driverless cars. So far, empirical evidence supporting this hypothesis is missing. To analyze the influence of autonomous driving on mobility behavior and to uncover user preferences, which serve as an indicator for future travel mode choices, we conducted an online survey with a paired comparison of current and future travel modes with 302 German participants. The results do not confirm the hypothesis that ownership will become an outdated model in the future. Instead they suggest that private cars, whether traditional or fully automated, will remain the preferred travel mode. At the same time, carsharing will benefit from full automation more than private cars. However, findings indicate that the growth of carsharing will mainly be at the expense of public transport, showing that more effort should be placed in making public transportation more attractive if sustainable mobility is to be developed.
Friction effects impose a requirement for the supplementary amount of torque to be produced in actuators for a robot to move, which in turn increases energy consumption. We cannot eliminate friction, but we can optimize motions to make them more energy efficient, by considering friction effects in motion computations. Optimizing motions means computing efficient joint torques/accelerations based on different friction torques imposed in each joint. Existing friction forces can be used for supporting certain types of arm motions, e.g standing still.
Reducing energy consumption of robot's arms will provide many benefits, such as longer battery life of mobile robots, reducing heat in motor systems, etc.
The aim of this project is extending an already available constrained hybrid dynamic solver, by including static friction effects in the computations of energy optimal motions. When the algorithm is extended to account for static friction factors, a convex optimization (maximization) problem must be solved.
The author of this hybrid dynamic solver has briefly outlined the approach for including static friction forces in computations of motions, but without providing a detailed derivation of the approach and elaboration that will show its correctness. Additionally, the author has outlined the idea for improving the computational efficiency of the approach, but without providing its derivation.
In this project, the proposed approach for extending the originally formulated algorithm has been completely derived and evaluated in order to show its feasibility. The evaluation is conducted in simulation environment with one DOF robot arm, and it shows correct results from the computation of motions. Furthermore, this project presents the derivation of the outlined method for improving the computational efficiency of the extended solver.
Bei der Übertragung und Speicherung von Daten ist es eine wesentliche Frage, inwieweit die Daten komprimiert werden können, ohne dass deren Informationsgehalt verloren geht.
Ein Maß für den Informationsgehalt von Daten ist also von grundlegender Bedeutung. Vor etwa siebzig Jahren hat C. E. Shannon ein solches Maß eingeführt und damit das Lehr- und Forschungsgebiet der Informationstheorie begründet, welches seit dem bis heute hin wesentlich zur Konzeption und Realisierung von Informationsund Kommunikationstechnologien beigetragen hat. Etwa zwanzig Jahre später hat A. N. Kolmogorov ein anderes Maß für den Informationsgehalt von Daten eingeführt. Während die Shannonsche Informationstheorie zum Curriculum von mathematischen, informatischen und elektrotechnischen Studiengängen gehört, ist die Algorithmische Informationstheorie von Kolmogorov weit weniger bekannt und eher Gegenstand von speziellen Lehrveranstaltungen.
Seit einigen Jahren nimmt allerdings die Beschäftigung mit dieser Theorie zu, zumal in der einschlägigen Literatur von erfolgreichen praktischen Anwendungen der Theorie berichtet wird. Die vorliegende Arbeit gibt eine Einführung in grundlegende Ideen dieser Theorie und beschreibt deren Anwendungsmöglichkeiten bei einigen ausgewählten Problemstellungen der Theoretischen Informatik.
Die Ausarbeitung kann als Skript für einführende Lehrveranstaltungen in die Algorithmische Informationstheorie sowie als Lektüre zur Einarbeitung in die Thematik als Ausgangspunkt für Forschungs- und Entwicklungsarbeiten verwendet werden.
The increasing complexity of tasks that are required to be executed by robots demands higher reliability of robotic platforms. For this, it is crucial for robot developers to consider fault diagnosis. In this study, a general non-intrusive fault diagnosis system for robotic platforms is proposed. A mini-PC is non-intrusively attached to a robot that is used to detect and diagnose faults. The health data and diagnosis produced by the mini-PC is then standardized and transmitted to a remote-PC. A storage device is also attached to the mini-PC for data logging of health data in case of loss of communication with the remote-PC. In this study, a hybrid fault diagnosis method is compared to consistency-based diagnosis (CBD), and CBD is selected to be deployed on the system. The proposed system is modular and can be deployed on different robotic platforms with minimum setup.
Robot deployment in realistic dynamic environments is a challenging problem despite the fact that robots can be quite skilled at a large number of isolated tasks. One reason for this is that robots are rarely equipped with powerful introspection capabilities, which means that they cannot always deal with failures in a reasonable manner; in addition, manual diagnosis is often a tedious task that requires technicians to have a considerable set of robotics skills.
Robot deployment in realistic environments is challenging despite the fact that robots can be quite skilled at a large number of isolated tasks. One reason for this is that robots are rarely equipped with powerful introspection capabilities, which means that they cannot always deal with failures in an acceptable manner; in addition, manual diagnosis is often a tedious task that requires technicians to have a considerable set of robotics skills. In this paper, we discuss our ongoing efforts to address some of these problems. In particular, we (i) present our early efforts at developing a robotic black box and consider some factors that complicate its design, (ii) explain our component and system monitoring concept, and (iii) describe the necessity for remote monitoring and experimentation as well as our initial attempts at performing those. Our preliminary work opens a range of promising directions for making robots more usable and reliable in practice.
A Method for the Sustainable Documentation of Operations Processes in Parcel Distribution Centers
(2018)
There is often no common understanding on operational processes in logistics companies as they are not properly documented. Hence, people execute the same process differently and training is conducted by experienced operators on an ad-hoc basis. Furthermore, continuous process improvement is hampered as neither the ideal process nor current issues in as-is processes are visible. A major reason for the missing documentation is the complexity of existing business process modelling languages. Modelling experts are required for initially describing the processes and also for updating the models after process changes. Furthermore, operations people are usually not used to read complex process models in EPCs or BPMN diagrams. In order to overcome these limitations, a domain-specific modelling language which facilitates maintaining up-to-date process models has been designed with a large logistics company in Germany. The paper at hand briefly describes this language and illustrates the method on how to apply it in operations environments.
This paper analyzes the complex effects and risks of social protection programmes in Ghana and Kenya on poor people’s human wellbeing, voice and empowerment and interactions with the social protection regulatory framework and policy instruments. For this purpose, it adopts a comprehensive Inclusive Development framework to systematically explore the complex effects of cash transfers and health insurance at the individual, household and community level. The findings highlight the positive provisionary and preventive effects of social protection, but also illustrate that the poorest are still excluded and that promotive effects, in the form of enhanced productivity, manifest themselves mainly for the people who are less resource poor. They can build more effectively upon an existing asset base, capabilities, power and social relations to counter the exclusionary mechanisms of the system, address inequity concerns and offset the transaction costs of accessing and benefitting from social protection. The inclusive development framework enables to lay these complex effects and interactions bear, and points to areas that require more longitudinal and mixed methodology research.
The paper contributes to the debate on the political economy of implementation of propoor social policy. It argues for a broadening of the debate, which is dominated by technocratic arguments, emphasizing the lack of financial resources, technology or skills as the major barriers for effective implementation. Describing the dynamic interplay of ‘formal’ operational programme structures and ‘informal’ traditional institutions in delivering the CT-OVC – the largest and oldest cash transfer programme in Kenya – it argues for the need to look more closely into the local political economy as an important mediating arena for implementing social policies. Implementation is heavily contingent upon the local social, political and institutional context that influences and shapes its outcomes. These processes are highly dynamic and ambivalent evolving between ‘formal’ and ‘informal’ structures and institutions. They may change over time and place, challenging the implicit assumption that programmes are evenly implemented across geographic and political entities.
Innovative Technologien, veränderte Anbieterstrukturen, stets neue Leistungsangebote und wandelnde Kundenanforderungen prägen und verändern von Beginn an das Erscheinungsbild des TK-Marktes. Unter Berücksichtigung einer Betrachtung im Zeitablauf lässt sich der Markt in drei aufeinanderfolgende Phasen einteilen: 1. Marktöffnung, 2. Konsolidierung und Optimierung, 3. Automatisierung. Die Phasen sind selbstverständlich nicht Überschneidungsfrei, geben jedoch einen Hinweis auf die strukturellen Veränderungen des Marktes.
Die Optimierung von Produktionsprozessen steht im Vordergrund jedes Produzenten, vor allem im Hinblick auf den optimalen Erntezeitpunkt. Zur Pflückreife sollen Kirschen als nicht-klimakterische Früchte eine optimale und hochwertige Fruchtqualität aufweisen, eine ausreichende Anzahl an Erntehelfern, Pflückhilfen, Transportkisten, Sortier- und Lagereinrichtungen sowie Absatzwege vorhanden sein. Aus diesem Grund entwickelten Wissenschaftler in der Vergangenheit diverse Reifeindices und Erntemodelle zur Bestimmung des optimalen Erntezeitpunkts von Früchten, erst an Äpfeln, dann für Steinobst.