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Für die Entwicklung steuerungstechnischer Sicherheitsfunktionen muss ab 2012 die Normen EN ISO 13849-1 oder EN 62061 befolgt werden, die sowohl Anforderungen an die Hardware als auch Anforderungen an die Software beschreibt. Die Anforderungen an die Software spielten bis vor einigen Jahren kaum eine Rolle, da Sicherheitsfunktionen vorzugsweise in Hardware realisiert wurden. Heutzutage ist es jedoch sehr häufig üblich, Sicherheitsfunktionen mit einer dafür geeigneten programmierbaren SPS zu realisieren. Die neuen Normen bzgl. der sicheren Steuerung von Maschinen verlangen neben der Quantifizierung der Hardware-Ausfallraten von Sicherheitsfunktionen noch ein Management der Sicherheitsfunktionen. Dazu gehört auch ein Management der Softwareentwicklung für Sicherheitsfunktionen, um systematische Fehler zu minimieren. Dieses Management der Softwareentwicklung wird im Wesentlichen durch das V-Modell repräsentiert. Für die Maschinebauindustrie darf dieser Managementprozess nicht zu aufwendig sein, ansonsten wird dieser in der Praxis nur schwer angenommen. Eine Möglichkeit der Abarbeitung des V-Modells wird vorgestellt. Wahrscheinlich ist diese aufgezeigte Möglichkeit für die Industrie noch zu aufwendig.
People have dreamed of machines, which would free them from unpleasant, dull, dirty and dangerous tasks and work for them as servants, for centuries if not millennia. Service robots seem to finally let these dreams come true. But where are all these robots that eventually serve us all day long, day for day? A few service robots have entered the market: domestic and professional cleaning robots, lawnmowers, milking robots, or entertainment robots. Some of these robots look more like toys or gadgets rather than real robots. But where is the rest? This is a question, which is asked not only by customers, but also by service providers, care organizations, politicians, and funding agencies. The answer is not very satisfying. Today’s service robots have their problems operating in everyday environments. This is by far more challenging than operating an industrial robot behind a fence. There is a comprehensive list of technical and scientific problems, which still need to be solved. To advance the state of the art in service robotics towards robots, which are capable of operating in an everyday environment, was the major objective of the DESIRE project (Deutsche Service Robotik Initiative – Germany Service Robotics Initiative) funded by the German Ministry of Education and Research (BMBF) under grant no. 01IME01A. This book offers a sample of the results achieved in DESIRE.
Open Source ERP-Systeme
(2012)
Mit Free and Open Source Software können die IT-Kosten in erheblichem Umfang gesenkt werden. Wegen ihres hohen Durchdringungsgrades in Unternehmen und des damit verbundenen Kostenblocks gilt dies insbesondere für Free and Open Source (FOS-) ERP-Systeme. Zwar sind die Verbreitung und die Akzeptanz von FOS-ERP-Systemen in den letzten Jahren schon stark angewachsen, durch eine verbesserte Markttransparenz lassen sich aber noch weitere Potenziale erschließen. Bestehende Marktübersichten für FOS-ERP-Systeme sind jedoch wenig umfassend. Vor diesem Hintergrund wurde ein Marktspiegel mit detaillierten Angaben zu den verschiedenen FOS-ERP-Systemen erstellt.
ERP systems are being used throughout the whole enterprise and are therefore responsible for a high percentage of IT expenses. The use of Free and Open Source ERP systems (FOS ERP systems) can help to reduce these IT costs. Though the acceptance of FOS ERP systems has increased enormously in the last years, even more entreprises would use FOS ERP systems to support their order processing, if the FOS ERP market was more transparent. Existing market surveys are less comprehensive. Therefore, a detailed market guide was developed.
We present our approach to extend a Virtual Reality software framework towards the use for Augmented Reality applications. Although VR and AR applications have very similar requirements in terms of abstract components (like 6DOF input, stereoscopic output, simulation engines), the requirements in terms of hardware and software vary considerably. In this article we would like to share the experience gained from adapting our VR software framework for AR applications. We will address design issues for this task. The result is a VR/AR basic software that allows us to implement interactive applications without fixing their type (VR or AR) beforehand. Switching from VR to AR is a matter of changing the configuration file of the application. We also give an example of the use of the extended framework: Augmenting the magnetic field of bar magnets in physics classes. We describe the setup of the system and the real-time calculation of the magnetic field, using a GPU.
Using virtual environment systems for road safety education requires a realistic simulation of road traffic. Current traffic simulations are either too restricted in their complexity of agent behavior or focus on aspects not important in virtual environments. More importantly, none of them are concerned with modeling misbehavior of traffic participants which is part of every-day traffic and should therefore not be neglected in this context. We present a concept for a traffic simulation that addresses the need for more realistic agent behavior with regard to road safety education. The two major components of this concept are a simulation of persistent agents which minimizes computational overhead and a model of cognitive processes of human drivers combined with psychological personality profiles to allow for individual behavior and misbehavior.
This paper compares the memory allocation of two Java virtual machines, namely Oracle Java HotSpot VM 32-bit (OJVM) and Jamaica JamaicaVM (JJVM). The basic difference of the architectures in both machines is that the JamaicaVM uses fixed-size blocks for allocating objects on the heap. The basic difference of the architectures is that the JJVM uses fixed size block allocation on the heap. This means that objects have to be split into several connected blocks if they are bigger than the specified block-size. On the other hand, for small objects a full block must be allocated. The paper contains both theoretical and experimental analysis on the memory-overhead. The theoretical analysis is based on specifications of the two virtual machines. The experimental analysis is done with a modified JVMTI Agent together with the SPECjvm2008 Benchmark.
This paper describes adaptive time frequency analysis of EEG signals, both in theory as well as in practice. A momentary frequency estimation algorithm is discussed and applied to EEG time series of test persons performing a concentration experiment. The motivation for deriving and implementing a time frequency estimator is the assumption that an emotional change implies a transient in the measured EEG time series, which again are superimposed by biological white noise as well as artifacts. It will be shown how accurately and robustly the estimator detects the transient even under such complicated conditions.
Along with the success of the digitally revived stereoscopic cinema, other events beyond 3D movies become attractive for movie theater operators, i.e. interactive 3D games. In this paper, we present a case that explores possible challenges and solutions for interactive 3D games to be played by a movie theater audience. We analyze the setting and showcase current issues related to lighting and interaction. Our second focus is to provide gameplay mechanics that make special use of stereoscopy, especially depth-based game design. Based on these results, we present YouDash3D, a game prototype that explores public stereoscopic gameplay in a reduced kiosk setup. It features live 3D HD video stream of a professional stereo camera rig rendered in a real-time game scene. We use the effect to place the stereoscopic effigies of players into the digital game. The game showcases how stereoscopic vision can provide for a novel depth-based game mechanic. Projected trigger zones and distributed clusters of the audience video allow for easy adaptation to larger audiences and 3D movie theater gaming.
The relative contributions of radial and laminar optic flow to the perception of linear self-motion
(2012)
When illusory self-motion is induced in a stationary observer by optic flow, the perceived distance traveled is generally overestimated relative to the distance of a remembered target (Redlick, Harris, & Jenkin, 2001): subjects feel they have gone further than the simulated distance and indicate that they have arrived at a target's previously seen location too early. In this article we assess how the radial and laminar components of translational optic flow contribute to the perceived distance traveled. Subjects monocularly viewed a target presented in a virtual hallway wallpapered with stripes that periodically changed color to prevent tracking. The target was then extinguished and the visible area of the hallway shrunk to an oval region 40° (h) × 24° (v). Subjects either continued to look centrally or shifted their gaze eccentrically, thus varying the relative amounts of radial and laminar flow visible. They were then presented with visual motion compatible with moving down the hallway toward the target and pressed a button when they perceived that they had reached the target's remembered position. Data were modeled by the output of a leaky spatial integrator (Lappe, Jenkin, & Harris, 2007). The sensory gain varied systematically with viewing eccentricity while the leak constant was independent of viewing eccentricity. Results were modeled as the linear sum of separate mechanisms sensitive to radial and laminar optic flow. Results are compatible with independent channels for processing the radial and laminar flow components of optic flow that add linearly to produce large but predictable errors in perceived distance traveled.
Interactive Distributed Rendering of 3D Scenes on Multiple Xbox 360 Systems and Personal Computers
(2012)
Um eine Software fertigzustellen und dem Endkunden zu übergeben muss zunächst der Entwicklungsprozess durchschritten werden. Das zügige Durchlaufen dieses Entwicklungsprozesses ist besonders für den Endkunden von entscheidender Bedeutung, da die Wartezeit auf das Softwareprodukt für ihn reduziert wird. Problematisch könnte beispielsweise dabei ein modulares Vorgehen werden, wenn zunächst alle einzelnen Teilkomponenten eines Softwareproduktes entwickelt und diese daraufhin in einer anschließenden Phase, auch Integrationsphase genannt, zusammengefügt würden. Die Länge dieser Integrationsphase kann nur schwer vorausgesagt werden, so dass weder das Entwicklerteam noch der Endkunde wissen, wie lang die Fertigstellung des Produktes dauern wird. Dabei entsteht ein weiterer Nachteil. Da die Komponenten separat voneinander entwickelt werden, könnte es passieren, dass diese beim finalen Zusammenfügen nicht kompatibel sein und müssten, falls notwendig, angepasst werden. Die Folge wäre eine Verschwendung von personellen und somit auch finanziellen Ressourcen seitens des entwickelnden Unternehmens.
Die Matrix-Vektor-Multiplikation für dünn besetzte Matrizen (SpMV) stellt für weitreichende wissenschaftliche Anwendungen eine der Kernoperationen des High-Performance-Computing-Bereichs dar. Für die verteilte Berechnung mit immer beliebter werdenden hybriden Rechenclustern kommt dabei die Frage nach einer geeigneten Partitionierungsstrategie für die Verteilung von Daten und Berechnung auf. Diese Arbeit beschäftigt sich damit welchen Einfluss die Struktur der Matrix und die unterschiedlichen Prozessortypen auf die Leistung der SpMV haben und schlägt ein Modell vor, um für diese eine lastbalancierte Verteilung zu erreichen. Wesentliche Bestandteile sind dabei die Laufzeitvorhersage für aktuelle CPUs und GPUs basierend auf einem abgewandelten Roofline-Modell sowie die bewährte Methode der Graph-Partitionierung.
Distributed computing environments allow collaborative problem solving across teams and organisations. A fundamental precondition for collaboration is the ability to find available participants and be able to exchange information. One way to approach this conceptual formulation are central directories or registry services. A major disadvantage of centralized components is, that they limit the flexibility to form ad hoc networks that are targeted to solve a specific problem. To facilitate flexible and dynamic collaborations, ideas from decentralized and self-organising networks can be combined with concepts of service oriented computing. This project aims to investigate potential solutions for dynamic discovery of network participants and outlines how to manage challenges associated with the development of a discovery protocol for distributed systems. During the course of this project a prototypical implementation was created that integrates into the open source distributed, collaborative problem solving environment RCE [9]. It is currently developed at the German Aerospace Center (DLR) but is planned to make the framework available to broader community.
In der Arbeit wurde ein Steuerungsframework für die LAMA-Bibliothek (http://www.libama.org) zur Konfiguration von Lösern linearer Gleichungssysteme entwickelt. Hierzu wurde ein Parser mit der Boost.Spirit-Biblithek realisiert, der die Laufzeitinterpretation einer domänenspezifische Sprache (DSL) erlaubt. Durch die Konfigurationssprache ist es möglich, Löser ohne Einschränkungen über ihre ID zu verknüpfen, diesen Lösern Logger und logisch verknüpfte Haltekriterien zuzuordnen.
For the case when the abstraction of instantaneous state transitions is adopted, this paper proposes to start fault detection and isolation in an engineering system from a single time-invariant causality bond graph representation of a hybrid model. To that end, the paper picks up on a long-known proposal to model switching devices by a transformer modulated by a Boolean variable and a resistor in fixed conductance causality accounting for its ON resistance. Bond graph representations of hybrid system models developed in this way have been used so far mainly for the purpose of simulation. The paper shows that they can well constitute an approach to the bond-graph-based quantitative fault detection and isolation of hybrid models. Advantages are that the standard sequential causality assignment procedure can be a used without modification. A single set of analytical redundancy relations valid for all physically feasible system modes can be (automatically) derived from the bond graph. Stiff model equations due to small values of the ON resistance in the switch model may be avoided by symbolic reformulation of equations and letting the ON resistance of some switches tend to zero, turning them into ideal switches.
First, for two examples considered in the literature, it is shown that the approach proposed in this paper can produce the same analytical redundancy relations as were obtained from a hybrid bond graph with controlled junctions and the use of a sequential causality assignment procedure especially for fault detection and isolation purpose. Moreover, the usefulness of the proposed approach is illustrated in two case studies by its application to standard switching circuits extensively used in power electronic systems and by simulation of some fault scenarios. The approach, however, is not confined to the fault detection and isolation of such systems. Analytically validated simulation results obtained by means of the program Scilab give confidence in the approach.
A bond graph representation of switching devices known for a long time has been a modulated transformer with a modulus b(t)∈{0,1}∀t≥0 in conjunction with a resistor R:Ron accounting for the ON-resistance of a switch considered non-ideal. Besides other representations, this simple model has been used in bond graphs for simulation of the dynamic behaviour of hybrid systems. A previous article of the author has proposed to use the transformer–resistor pair in bond graphs for fault diagnosis in hybrid systems. Advantages are a unique bond graph for all system modes, the application of the unmodified standard Sequential Causality Assignment Procedure, fixed computational causalities and the derivation of analytical redundancy relations incorporating ‘Boolean’ transformer moduli so that they hold for all system modes. Switches temporarily connect and disconnect model parts. As a result, some independent storage elements may temporarily become dependent, so that the number of state variables is not time-invariant. This article addresses this problem in the context of modelling and simulation of fault scenarios in hybrid systems. In order to keep time-invariant preferred integral causality at storage ports, residual sinks previously introduced by the author are used. When two storage elements become dependent at a switching time instance ts, a residual sink is activated. It enforces that the outputs of two dependent storage elements become immediately equal by imposing the conjugate3 power variable of appropriate value on their inputs. The approach is illustrated by the bond graph modelling and simulation of some fault scenarios in a standard three-phase switched power inverter supplying power into an RL-load in a delta configuration. A well-developed approach to model-based fault detection and isolation is to evaluate the residual of analytical redundancy relations. In this article, analytical redundancy relation residuals have been computed numerically by coupling a bond graph of the faulty system to one of the non-faulty systems by means of residual sinks. The presented approach is not confined to power electronic systems but can be used for hybrid systems in other domains as well. In further work, the RL-load may be replaced by a bond graph model of an alternating current motor in order to study the effect of switch failures in the power inverter on to the dynamic behaviour of the motor.
This article concerns with the accessibility of Business process modelling tools (BPMo tools) and business process modelling languages (BPMo languages). Therefore the reader will be introduced to business process management and the authors' motivation behind this inquiry. Afterwards, the paper will reflect problems when applying inaccessible BPMo tools. To illustrate these problems the authors distinguish between two different categories of issues and provide practical examples. Finally the article will present three approaches to improve the accessibility of BPMo tools and BPMo languages.
Jede Führungskraft hat ein bestimmtes Menschenbild, das ihre Arbeit und den Umgang mit den Mitarbeitern prägt. Diese Menschenbilder sind auch einem historischen Wandel unterworfen. Denn im Lauf der Jahrzehnte haben sich unsere Vorstellungen vom Menschen als Mitarbeiter grundlegend gewandelt. Welche Konsequenzen dieser Wandel für die Mitarbeiterführung hat, untersucht der folgende Artikel.
This article concerns the design and development of Information- and Communication Technology, in particular computer systems in regard to the demographic transition which will influence user capabilities. It is questionable if current applied computer systems are able to meet the requirements of altered user groups with diversified capabilities. Such an enquiry is necessary based on actual forecasts leading to the assumption that the average age of employees in enterprises will increase significantly within the next 50-60 years, while the percentage of computer aided business tasks, operated by human individuals, rises from year to year. This progress will precipitate specific consequences for enterprises regarding the design and application of computer systems. If computer systems are not adapted to altered user requirements, efficient and productive utilisation could be negatively influenced. These consequences constitute the motivation to extend traditional design methodologies and thereby ensure the application of computer systems that are usable, independent of user capabilities.
IT-Radar für BPM und ERP
(2012)
Mit dem IT-Radar für BPM und ERP liegt ein Instrument zur Unterstützung der aktiven Steuerung und Validierung der IT-Strategie vor. Die ersten Ergebnisse zeigen, dass klassische Aufgaben des BMP- und ERP-Managements wie Prozessintegration nach wie vor hohe Aktualität haben und neue Themen wie die dienstliche Nutzung privater Endgeräte (BYOD - Bring Your Own Device), die Verarbeitung von sehr großen Datenmengen (Big Data) und Echtzeitverarbeitung (In-Memory Computing) zwar intensiv auf die Agenda des Chief Information Officers (CIO) drängen, aber klassische Aufgaben nicht verdrängen.
IT-Controlling
(2012)
Big Data
(2012)
Die vorliegende wirtschaftswissenschaftliche Studie, die vom Forschungsinstitut für Glücksspiel und Wetten am BusinessCampus der Hochschule Bonn-Rhein-Sieg im Auftrag der Deutschen Automatenindustrie erstellt wurde, setzt sich kritisch-methodisch mit den bestehenden Annahmen über die sozialen Folgekosten von Spielsucht in Bezug auf gewerbliche Spielautomaten in Gastbetrieben und Spielhallen auseinander. Sie kommt hierbei zu neuen, fundierten Bewertungen, insbesondere im Vergleich mit Risiken bei Spielbanken und Lotterien. In einer Kosten-Nutzen-Bilanz überwiegen die Nutzenaspekte des gewerblichen Geld-Gewinnspiels die Kosten um ein Mehrfaches.
Mikroökonomie: Grundlagen der Wissenschaft von Märkten und Institutionen wirtschaftlichen Handelns
(2012)
Die Mikroökonomie gehört zu den Kernfächern in wirtschaftswissenschaftlichen Bachelor- und Masterprogrammen. Das vorliegende Buch bietet mit vielen Beispielen und Aufgaben, beispielsweise aus den Gebieten Arbeits-, Kapital-, Versicherungs-, Güter-, und Gesundheitsmarkt, die Möglichkeit, die Theorie anzuwenden und nachzuvollziehen.
forschung@h-brs
(2011)
Topics
Dialogue University President Hartmut Ihne and Jakob Rhyner, Vice Rector of the United Nations University (UNU), talk about common goals and the concept of regional internationality ...
Studies and Teaching University scores high with the Teaching Quality Pact (Pro-MINT-us), career training and Bachelor studies all in one, three attractive Master’s programmes set up, central e-Learning platform online, International Centre for Sustainable Development already hard at work ...
Research Graduate Institute establishes new Ph.D. culture, research focus on visual computing secures third-party funding, energy harvesting project wins university competition, research on the impact of zero gravity on arteries, security systems protect against car thieves ...
Campus Centre for Science and Technology Transfer, International Welcome Centre - a first stop for foreign students, alumni coordinator keeps in close contact with former students, hackathon brings students from around the world together, H-BRS prepared for the double Abitur year ...
What if ... ... the Bonn-Rhein-Sieg University of Applied Sciences did not exist? Personal answers to an unusual question ...
Region H-BRS- a strong engine for the region, research centre for region’s SMEs looks for investors, companies invest in scholarships, students advise the Alexander- Koenig-Gesellschaft, BusinessCampus opens a third location, concept for medical tourism along the Rhine corridor ...
International Mechanical engineering students in Ethiopia, businesses and universities collaborate in Ghana, university partnership with Namibia, Study Buddies for foreign students, student initiates German-Argentine Master’s degree, Spanish teacher conference, intercultural training for all university staff ...
Facts and Figures Programmes of study, statistics, organisational structure, international partnerships, awards ...
Die sogenannte Regionalstudie trägt den Langtitel "Regionalwirtschaftliche Bedeutung der Hochschule Bonn-Rhein-Sieg und zukünftige Einbindung in die strategische Entwicklung der Region" und wurde 2010 erstellt und 2011 veröffentlicht. Sie analysiert die regionalwirtschaftliche Bedeutung der Hochschule primär unter quantitativen Aspekten und aus externer Sicht. Viele der daraus resultierenden Anregungen für die strategische Ausrichtung der Hochschule wurden bereits während der Feldphase im Hochschulentwicklungsplan aufgegriffen, konnten wegen der Parallelität aber nicht in der Studie Eingang finden.
Die Analyse zeigt, welchen Beitrag die Hochschule für die regionale Entwicklung leisten kann - im Einklang mit den Kommunen, der Gebietskörperschaften und der regional ansässigen Unternehmen.
DNA Sequencing
(2011)
Isolation of DNA and RNA
(2011)
Polymerase Chain Reaction
(2011)
Streptococcus agalactiae is the leading cause of bacterial sepsis and meningitis in neonates and is also the causative agent of several serious infections in immunocompromised adults. S. agalactiae encounters multiple niches during an infection, suggesting that regulatory mechanisms control the expression of specific virulence factors in this bacterium. The present study describes the functional characterization of a gene from S. agalactiae, designated rga, which encodes a protein with significant similarity to members of the RofA-like protein (RALP) family of transcriptional regulators. After deletion of the rga gene in the genome of S. agalactiae, the mutant strain exhibited significantly reduced expression of the genes srr-1 and pilA, which encode a serine-rich repeat surface glycoprotein and a pilus protein, respectively, and moderately increased expression of the fbsA gene, which encodes a fibrinogen-binding protein. Electrophoretic mobility shift assays demonstrated specific DNA binding of purified Rga to the promoter regions of pilA and fbsA, suggesting that Rga directly controls pilA and fbsA. Adherence assays revealed significantly reduced binding of the Δrga mutant to epithelial HEp-2 cells and to immobilized human keratin 4, respectively. In contrast, the adherence of the Δrga mutant to A549 cells and its binding to human fibrinogen was significantly increased. Immunoblot and immunoelectron microscopy revealed that the quantity of pilus structures was significantly reduced in the Δrga mutant compared with the parental strain. The wild-type phenotype could be restored by plasmid-mediated expression of rga, demonstrating that the mutant phenotypes resulted from a loss of Rga function.
Balanites aegyptiaca (Balanitaceae) is a widely grown desert plant with multiuse potential. In the present paper, a crude extract from B. aegyptiaca seeds equivalent to a ratio of 1 : 2000 seeds to the extract was screened for antiplasmodial activity. The determined IC(50) value for the chloroquine-susceptible Plasmodium falciparum NF54 strain was 68.26 μg/μL ± 3.5. Analysis of the extract by gas chromatography-mass spectrometry detected 6-phenyl-2(H)-1,2,4-triazin-5-one oxime, an inhibitor of the parasitic M18 Aspartyl Aminopeptidase as one of the compounds which is responsible for the in vitro antiplasmodial activity. The crude plant extract had a K(i) of 2.35 μg/μL and showed a dose-dependent response. After depletion of the compound, a significantly lower inhibition was determined with a K(i) of 4.8 μg/μL. Moreover, two phenolic compounds, that is, 2,6-di-tert-butyl-phenol and 2,4-di-tert-butyl-phenol, with determined IC(50) values of 50.29 μM ± 3 and 47.82 μM ± 2.5, respectively, were detected. These compounds may contribute to the in vitro antimalarial activity due to their antioxidative properties. In an in vivo experiment, treatment of BALB/c mice with the aqueous Balanite extract did not lead to eradication of the parasites, although a reduced parasitemia at day 12 p.i. was observed.
JNK1, but Not JNK2, Is Required in Two Mechanistically Distinct Models of Inflammatory Arthritis
(2011)
Die Debatte um das menschliche Erkenntnisvermögen, also die Frage nach der Art und Weise, wie Menschen Wissen und Erkenntnis erlangen, ist nicht neu, sondern sie stellt sich seitdem philosophische Fragen gestellt werden – ohne dass allerdings über die Jahrhunderte hinweg eine definitive Antwort auf diese Frage gefunden werden konnte.
Dieses Buch ist kein Lehrbuch im eigentlichen Sinne. Aus Vorlesungsskripten entstanden, verfolgt es das Ziel, den Studenten der Wirtschaftswissenschaften an Fachhochschulen und Universitäten eine systematische, auf das Wesentliche konzentrierte Lernhilfe mit Übungen zur Vorbereitung auf Prüfungen im Grundstudium im Fach „Unternehmensbesteuerung“ anzubieten.
In this paper, the performance evaluation of Frequency Modulated Chaotic On-Off Keying (FM-COOK) in AWGN, Rayleigh and Rician fading channels is given. The simulation results show that an improvement in BER can be gained by incorporating the FM modulation with COOK for SNR values less than 10dB in AWGN case and less than 6dB for Rayleigh and Rician fading channels.
"Innovation Journalism ist die Politikberichterstattung der Zukunft" Interview mit David Nordfors
(2011)
Die Anforderungen an die Tragfähigkeit von Seilrollen aus Guss-Polyamiden nehmen aufgrund der Erwartungen hinsichtlich der maximal zu realisierenden Hublasten bei neueren Förder- und Hebegeräte stetig zu. Die heutige Konstruktionspraxis erlaubt für normale Betriebsbedingungen eine gesicherte Auslegung der Seilrollen. Aus jahrelanger Erfahrung sind hierfür Grenzwerte für maximal zulässigen Belastungen im Betrieb unter verschiedensten Betriebsbedingungen gewonnen worden. Jedoch ist bei steigenden Lasten, besserer Ausnutzung des Werkstoffpotenzials oder Modifikationen des Basiswerkstoffs nur noch eine eingeschränkte Bestimmung der tatsächlichen "Worst-Case"-Tragfähigkeit mit dieser Konstruktionspraxis möglich. Berechnungsmodelle einer neuen Bemessungsgrundlage basieren auf der Anwendung der Finite Elemente Methode. Die ersten Berechnungsmodelle aus der modifizierten Bemessungsgrundlage ermöglichen den Einfluss von geometrischen Änderungen der Form bzw. der Ausführung, von lokalen Materialeigenschaften und von realistischere Lastzustände auf den Deformationsund Spannungszustand einer Seilrolle theoretisch zu beschreiben. Weitere Berechnungsmodelle, die z.B. die Erwärmung der Seilrolle durch die Rollreibung zwischen Seil und Seilrolle sowie des Walkens durch die Bewegung des Seiles bei dynamischer Belastung beschreiben können, sind in der Entwicklung. Für den Konstrukteur werden zudem parametrisierte Geometrie-, Last- und FE-Modelle entwickelt, die eine schnelle und betriebssichere Dimensionierung von Seilrollen aus Guss-Polyamiden ermöglichen. Alle theoretischen Ergebnisse werden z.Z. durch umfangreiche Versuche abgesichert.
The small and remote households in Northern regions demand thermal energy rather than electricity. Wind turbine in such places can be used to convert wind energy into thermal energy directly using a heat generator based on the principle of the Joule machine. The heat generator driven by a wind turbine can reduce the cost of energy for heating system. However the optimal performance of the system depends on the torque-speed characteristics of the wind turbine and the heat generator. To achieve maximum efficiency of operation both characteristics should be matched. In the article the condition of optimal performance is developed and an example of the system operating at maximum efficiency is simulated.