Showing papers in "Elektrotechnik Und Informationstechnik in 2002"

LoL@: designing a location based UMTS application

Abstract: UMTS combines mobile communications and the Internet. After showing some fundamental issues of UMTS services, this paper presents LoL@, the Local Location Assistant. It is a prototype of a location based UMTS service, combining localization/navigation and multimedia. These components can be seen as “killer components”, they can be combined to provide various services over various networks.

Learning with progressive transductive support vector machine

Abstract: Support vector machine (SVM) is a new learning method developed in recent years based on the foundations of statistical learning theory. By taking a transductive approach instead of an inductive one in support vector classifiers, the working set can be used as an additional source of information about margins. Compared with traditional inductive support vector machines, transductive support vector machine is often more powerful and can give better performance. In transduction, one estimates the classification function at points within the working set using information from both the training and the working set data. This will help to improve the generalization performance of SVMs, especially when training data is inadequate. Intuitively, we would expect transductive learning to yield improvements when the training sets are small or when there is a significant deviation between the training and working set subsamples of the total population. In this paper, a progressive transductive support vector machine is addressed to extend Joachims' transductive SVM to handle different class distributions. It solves the problem of having to estimate the ratio of positive/negative examples from the working set. The experimental results show the algorithm is very promising.

Evaluation of lightning location data employing measurements of direct strikes to a radio tower

Abstract: A lightning location systems (LLS) provides large scale information for lightning strikes to ground. In addition to the event time and strike point position, the LLS gives estimates for the lightning peak current. For the end user of LLS data it is important to know the technical limits of the applied network in terms of detection efficiency, accuracy of the stroke location and peak current estimate. To establish a ground truth reference for comparison of natural lightning current parameters and the data of ALDIS (Austrian Lightning Detection & Information System), a telecommunication tower on Gaisberg near the city of Salzburg (Austria) was instrumented for direct lightning current measurement. Since the start of the tower experiment in 1998 we have recorded more than 200 lightning flashes to the tower. Based on the analysis of the current waveforms nearly all of them are so called upward initiated discharges. GPS time synchronization of both data sets allows a precise correlation of individual events measured at the tower and reported by the lightning location network.

Causalité institutionnelle : la futurité chez J. R. Commons

Abstract: L’une des contributions importantes de John R. Commons a l’economie institutionnaliste est de proposer le concept pragmatiste de futurite. Ce concept est, selon cet auteur, indispensable pour comprendre la necessaire inscription des actions economiques dans la temporalite et pour analyser ces actions selon leur logique de causalite propre : la causalite institutionnelle. Selon cette derniere, la futurite, structuree par l’action collective, est la cause de l’action economique presente. Une application a l’analyse de la transaction de marchandage est presentee.

L’entreprise comme organisation et comme institution. Un regard à partir de l’institutionnalisme de J.R. Commons

Abstract: Ce texte s’inscrit dans les debats theoriques sur l’analyse economique de l’entreprise en developpant une approche fondee sur les apports de l’ancien institutionnalisme et particulierement sur les conceptions de Commons. L’originalite de cette vision est que l’entreprise doit etre concue a la fois comme une organisation et comme une institution, ces deux notions etant intimement liees. Sur cette base, nous montrons, d’une part, que l’analyse de la coordination necessite de combiner les dimensions cognitives et politiques des regles constituant l’entreprise et, d’autre part, que la comprehension de l’entreprise ne peut etre isolee de celle de la structure institutionnelle de la societe et de sa dynamique historique.

Das Katastrophenhochwasser vom 7. August 2002 am Kamp — Eine erste Einschätzung

Abstract: In dieser Arbeit wird das Katastrophenhochwasser am Kamp vom 7. August 2002 aus hydrologischer Sicht analysiert. Niederschlags- und Abflussdaten der letzten 100 Jahre wurden ausgewertet, um dieses Ereignis einzuordnen. Die Niederschlage waren um 70% hoher als die grosten bisher beobachteten Werte. Die Abflusse betrugen rund das Dreifache des grosten bisher beobachteten Hochwassers. Die rechnerische Jahrlichkeit wurde mit mehreren tausend Jahren abgeschatzt. Nur bei einem Eisstos im 17. Jahrhundert wurde ein ahnlicher Wasserstand erreicht. Die bei diesen Untersuchungen gewonnenen Erkenntnisse ermoglichen auch eine neue Einschatzung, wie Hochwasserschutz und Warnung in Osterreich mit derart extremen Ereignissen umgehen kann. Uberflutbare Damme, Definition von Risikoflachen fur Extremereignisse und Installation von Fruhwarnsystemen konnen dazu beitragen.

A Conceptual Design For A Spaceborne 3D Imaging Lidar

Abstract: First generation spaceborne altimetric approaches are not well-suited to generating the few meter level horizontal resolution and decimeter accuracy vertical (range) resolution on the global scale desired by many in the Earth and planetary science communities. The present paper discusses the major technological impediments to achieving few meter transverse resolutions globally using conventional approaches and offers a feasible conceptual design which utilizes modest power kHz rate lasers, array detectors, photoncounting multi-channel timing receivers, and dual wedge optical scanners with transmitter point-ahead correction.

Cable Measurements Supporting xDSL Technologies

Abstract: The ongoing developments in the field of high-speed data transmission over twisted-pair cables (DSL-Digital Subscriber Line) leads to methods that can exploit the transmission media with increased efficiency. MIMO (Multiple-Input Multiple-Output) transmission, i.e., the coordinated use of many pairs within a bundle, is such an emering DSL technology. A further goal is to maintain a certain transmission quality in the presence of non-DSL noise. For example, cancellation techniques to combat narrowband radio interference, which is generated by radio amateur transmitters and may be picked up by the wire close to the subscriber or by the in-hourse wiring, become important.

Origin and abatement of tonal emission from high voltage transmission lines

Abstract: The origin of the locally unacceptable and intensive tonal 2f=100 Hz emission from overhead high voltage lines has been clearly traced by means of multiple diagnostics applied to a model line in the laboratory. Use of a special hydrophilic surface preparation has demonstrated a significant reduction of tonal acoustic noise emission after heavy rain.

On Controlled Switching of High Voltage Unloaded Transmission Lines

Abstract: The limitation of switching overvoltages on very high voltage transmission lines is traditionally carried out with the aid of circuit breakers — fitted with closing resistors. This widely used system has repeatedly shown itself to be highly efficient. Nevertheless, it is possible to envisage other methods, in particular, those giving control of the circuit breaker instant of closing. This paper examines the possibilities offered by controlled switching on UHV transmission lines and compares existing solutions. It takes into account the various network characteristics that may be encountered. It details the results in terms of overvoltage levels which could be attained, due to the performance of the circuit breaker. The paper also highlights the critical points relative to the application.

From Walrasian general equilibrium to incomplete contracts : making sense of institutions

Abstract: This paper explores the specific contribution of recent literature on incomplete contracts in comparison with the acontractual Walrasian general equilibrium as well as the complete optimal contracts of the Agency theory regarding the institutional identity of agents. It underlines a tension between the theoretical justification of contractual incompleteness on the one hand, and rationality postulate, on the other hand. It concludes the relevance of bounded rationality assumption to overcome some logical incoherencies of present incomplete contracts literature.

Grundlagen der Wahrscheinlichkeitsrechnung für iterative Decodierverfahren

Abstract: In dieser Ubersichtsarbeit werden die Grundgleichungen der iterativen Decodierung mittels elementarer Verfahren der Wahrscheinlichkeitsrechnung abgeleitet und zusammengestellt. Dabei zeigt sich, dass durch direkte Reprasentation einer Symbolzuverlassigkeit mittels der a-posteriori-Wahrscheinlichkeit diese Beziehungen einfach darzustellen sind, und die Prinzipien der iterativen Decodierung dadurch leicht fasslich formuliert werden konnen. Die Vorteile anderer gebrauchlicher Methoden zur Reprasentation von Symbolzuverlassigkeiten und deren Wechselbeziehungen werden diskutiert.

Long term experience on lightning acquisition in Italy and Austria and data application to the improvement of lightning performance

Abstract: Lightning location systems (LLS) have been in operation in Italy and Austria for about 10 years. The two networks have been running a collaboration sharing sensors data since the beginning. The importance of this collaboration is shown, analyzing the behavior of the two networks as standing alone or as cooperating. In particular a detailed analysis is run on a set of data, evaluating the importance of the other network sensors in the calculation of lightning and in the efficiency and accuracy of the final results. The application of LLS data to improve the lightning performance evaluation of transmission and distribution lines is analyzed. Lightning density at ground is a key factor for performance evaluation of transmission lines. More accurate and detailed maps than those standardized may be derived from LLS, indicating that standardized values (average values for an area) are not sufficiently accurate to describe the situation of a given territory. The use of LLS data to correlate faults and lightning is discussed. For MV lines, one of the particular problems discussed is the necessary accuracy in lightning location.

Mechanismen der Anreizregulierung

Abstract: Die Vorteile und Nachteile unterschiedlicher Regulierungsmodelle werden kurz behandelt, bevor die Anreize der Preisobergrenzenregulierung mit Hilfe einfacher Beispiele diskutiert werden. Die diskutierten Themen umfassen die Lange der Regulierungsperiode, die Anreize fur strategische Anpassungen bzw. Uberlegungen, wie diese vermieden werden konnen, und die Wirkung von individuellen Effizienzfaktoren. Abschliesend werden die Rahmenbedingungen der osterreichischen Preisobergrenzenregulierung kurz beschrieben.

ENUM — Phone numbers on the Internet

Abstract: The problem of a single identifier for multiple communication services can be solved with different approaches. One simple approach is the ENUM system developed by the IETF (Internet Engineering Task Force), using existing E. 164 telephone numbers, protocols and infrastructure to point to different services available under this identifier. The technical aspects of the underlying protocols and the administrative aspects of the distributed database used — the domain name system — are presented. This includes the related activities in ITU and ETSI and possible national implementations.

À propos de la distinction entre institution et organisation chez les institutionnalises : apports et limites

Abstract: L’apport de l’article est de montrer que l’ancien institutionnalisme (O.I) propose une distinction conceptuelle originale entre institution et organisation, notamment chez Veblen, distinction qui repose entre autres sur une theorie des actifs. L’O.I. se deploie sur arrangements institutionnel et organisationnel, conflits distributifs, en y apportant des elements fondateurs. Toutefois, Veblen a une certaine difficulte a faire de l’organisation un element endogene de l’institution, ce qui est moins patent chez Commons. Le Nouvel institutionnalisme ne peut repondre a cette distinction entre institution et organisation optant soit pour l’institution, soit pour l’organisation, ne se deployant que sur une seule combinaison privilegiee et ignorant la question du conflit distributif.

Sicherheit der Übertragungsnetze

Abstract: Im Zuge der europaweiten Offnung der Elektrizitatsmarkte sind eine starke Veranderung im internationalen Energieaustausch und eine zunehmende Auslastung der Ubertragungsnetze zu beobachten. Weiters ist durch die stetige Verbrauchszunahme und den veranderten Kraftwerkseinsatz sowie durch Stillegung von regional unwirtschaftlichen Kraftwerken ein erhohtes weitlaufiges Transportaufkommen festzustellen. Diese Faktoren haben aufgrund der zentralen Lage Osterreichs im UCTE-Netz einen starken Einfluss auf das osterreichische Ubertragungsnetz. Bedingt durch langwierige Genehmigungsverfahren und mangelnde regionale Akzeptanz von Seiten der Bevolkerung wird der seit Jahren von den verantwortlichen Netzbetreibern geplante und geforderte Ausbau eines leistungsfahigen osterreichischen Ubertragungsnetzes verzogert, so dass heute die Kapazitatsgrenze wichtiger innerosterreichischer Leitungen erreicht ist. Weitraumige nicht prognostizierbare Transitverschiebungen im umgebenden europaischen Verbundnetz fuhren somit zu kurzfristigen Engpassen und Leitungsbelastungen, die zeitweise bis an die thermische Kapazitatsgrenze reichen. Im Falle von Uberlastauslosungen und zu geringem Eigenerzeugungsanteil kame es in weiterer Folge zur Bildung von regionalen Netzinseln. Anhand von Simulationen wird das Abfangen einer Inselbildung in Nord-Ost-Osterreich durch Unterfrequenz-Lastanpassung und Einsatz der Kraftwerksregler bei hohem Eigenerzeugungsanteil bestatigt. Falls zukunftig der Eigenerzeugungsanteil weiter stark zuruckgehen sollte und das osterreichische Ubertragungsnetz nicht entsprechend dem europaischen Standard ausgebaut wird, konnen sich solche Inselbildungen zu Netzzusammenbruchen ausweiten.

Multi-user detection in multicarrier-CDMA systems

Abstract: The upcoming third generation mobile radio system in Europe is based on UMTS (Universal Mobile Telecommunications Standard). In order to supply access to a common transmission channel for several users, UMTS incorporates Code Division Multiple Access (CDMA). Besides a lot of practical advantages, CDMA suffers from multi-user interference limiting spectral efficiency dramatically. However, bandwidth is a very valuable resource and should be used as efficiently as possible. One appropriate mean to increase spectral efficiency of CDMA systems is multi-user detection. This paper gives an overview of different multi-user detection techniques and compares them with the conventional single-user detection including channel coding. Specifically, linear as well as nonlinear multi-user detectors are considered. Efficient realizations of linear detectors are presented and extended to improved nonlinear techniques. It is shown that nonlinear MUD including channel decoding can achieve a spectral efficiency twice as high as that of the well-known GSM standard (Global System for Mobile Communications) employing TDMA and FDMA.

Decision Premises, Institutions and Organisation

Abstract: In formal reasoning, premises are decisive; but most economists are reluctant to treat them as problematic, either for analysts or economic agents. After illustrating the significance of alternative premises for economic theory, we explore the implications of Knightian uncertainty and cognitive limitations for the formation and co-ordination of decision premises as well as the development of dispersed and asymmetric knowledge. Institutions help people to frame decision spaces while facilitating knowledge-sharing; and formal organisation promotes investment in decision-making systems and the development of organisation-specific institutions. A discussion of authority, trust and strategy concludes.

Benchmarking und Regulierung elektrischer Netze: internationale Erfahrungen und Konsequenzen für Österreich

Abstract: Im Zuge der Liberalisierung der Strommarkte bleiben die Ubertragungs- und Verteilnetze auch weiterhin von ihrer Struktur her naturliche Monopole. Um jedoch Wettbewerb auch im Netzbetrieb abzubilden, bedienen sich die internationalen Regulierungsbehorden grundlegend neuer Benchmarking- und Netztarifregulierungsverfahren. Das zentrale Ziel dieses Aufsatzes ist eine diesbezugliche Analyse und insbesondere die Ableitung von daraus resultierenden Schlussfolgerungen fur den zukunftigen Netzbetrieb in Osterreich. In liberalized electricity markets transmission and distribution grids still remain natural monopolies. In order to implement competitive elements also on the grid, international regulatory authorities make use of fundamentally new methods on benchmarking and grid regulation. The core objective of this paper is to analyze these new instruments and to derive conclusions for grid regulation in Austria in the future.

Control system design based on holistic eigenvalue allocation

Abstract: A trade-off between optimum allocation of the entire set of eigenvalues and the size of controller norm or a general actuator effort is carried out for continuous-time and discrete-time systems. Controllers achieving appropriate results are termed holistic. The design is based on the trace and determinant of the closed-loop state-space matrix. To solve the problem within the scope of actuating effort, the norm of the state controller matrixor the actuator effort transfer matrix are taken into consideration. The method is also extended for designing holistic observers. For preserving stability, a Lyapunov condition is included.

Non-conventional instrument transformers in high voltage substations

Abstract: Today non-conventional current and voltage transformers have achieved high performance. In addition, the digital output complies with the most stringent requirements of protective relays and meters. The designs take into account the harshest environmental conditions of temperature, vibrations and electromagnetic compatibility. Final solutions with respect to standardization of the interfaces will be available soon which will increase the number of on-site installations.

Der Einfluss dezentraler Erzeugung auf die Verteilnetze

Abstract: Im Zuge der Liberalisierung werden dezentrale Erzeuger verstarkt in die Verteilnetze einspeisen. Die Einflusse der neuen Netzkomponenten sind netzplanerisch zu analysieren, um sie im Sinne von Wirtschaftlichkeit und Versorgungsqualitat vorteilhaft zu nutzen. Neue Simulationsmodelle fur dynamisches und quasi-stationares Verhalten von erneuerbaren Energiequellen, Speichern, Netzkupplern und Stromerzeugungsanlagen mit Kraft-Warme-Kopplung wurden fur die Analyse zweier Pilotnetze mit dezentraler Erzeugung eingesetzt.

Prototype implementation of an assembly system for tissue engineered constructs

Abstract: In the course of the research described in this paper a prototype assembly system for the automated fabrication of customized, biodegradable bone implants for tissue engineering applications has been developed This work is part of a collaborative effort between the Handling Laboratory (hLab) of Fachhochschule Vorarlberg and the Bone Tissue Engineering Center (BETC) of Carnegie Mellon University Bone implants are built up using thin layers of highly porous, biodegradable polymer scaffold materials These layers can be seeded with cells prior to assembly The main focus of this work is robotic handling of the prefabricated polymer layers Additional components that are addressed include the cutting of contoured polymer layers from sheetstock and the assembly of the 21/2 dimensional layers to form 3D bone implants Cutting tests have been performed to assess different cutting technologies Assembly tests with mechanical connectors and fibrin adhesive have also been conducted These components are integrated within a robot cell to demonstrate overall system feasibility

Admissible short-time uncertainty in networked control systems

Abstract: Increasing in number, busses and wireless networks are used as signal transmission in control systems. Networked control systems of this kind are characterized by occasional or arbitrary time delay or interruptions of minor loops. These influences are modelled as short-time uncertainties, in contrast to robust control systems in the literature, which are mainly studied as families with time-invariant uncertainties. Severe uncertainties are taken into consideration even if they cause short-time instability. An uncertainty can be valuated admissible if the accompanying signal amplitude or energy increase remains bounded. A third-order example with unstable behavior in a short-time interval is carried out in detail.

Deregulierung und Sicherheit in der Energieversorgung@@@Deregulation and security of energy supply

Abstract: ZusammenfassungDie Versorgungssicherheit ist für die Volkswirtschaft von großer Bedeutung. Die langfristige Versorgungs-sicherheit betrachtet die Liefersicherheit der Energieressourcen, die kurzfristige betrachtet die Versorgungszuverlässigkeit der Kunden. Durch die Deregulierung haben die Netzbetreiber nur mehr die Aufgabe, einen zuverlässigen Netztransit zu ermöglichen, die Ressourcensicherheit ist Aufgabe des freien Strommarktes. Aufgrund einer Klassifizierung der im Netz möglichen Versorgungsunterbrechungen und des Funktionsverhaltens der Kundenanlagen ist eine Einteilung in Risikoklassen möglich. Die Kundenanlagen sind sensibler geworden und fallen teilweise bereits bei Dips aus, ohne dass die Möglichkeit für automatischen Wiederanlauf besteht. Aufgrund des Anlagenrisikos kann eine Bewertung durchgeführt werden, ob eine erhöhte Sicherheit der Netze oder unterbrechungsfreie Kundenanlagen wirtschaftlicher sind.AbstractThe security of supply is of great importance for the economy. The security of resources considers the availability of energy resources in the long run. The continuity of supply considers the reliable supply of the customers. As a consequence of deregulation, the network has now only the duty for reliable transmission, the reliability of energy supply is a task of the deliberated energy market. The classification of the different causes of interruptions of supply in a grid and of the functional behaviour of consumers enables a scaling of the risk of the consumer equipment. The customers have become more sensitive and have a breakdown even after a dip without an automatic restarting possibility. Based of the risk of breakdown a valuation can be performed to see if an improved security of network supply or an uninterruptible power supply at customer side is more economical.