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The harmonic and interharmonic analysis recommendations are contained in the latest International Electrotechnical Commission (IEC) standards on power quality. Measurement and analysis experiences have shown that great difficulties arise in the interharmonics detection and measurement with acceptable levels of accuracy. In this paper, the spectral leakage problems of the discrete Fourier transform due to synchronization errors of interharmonics are analyzed. The time-domain averaging is investigated for the processing of harmonics in the framework of the IEC standards. A difference filter is proposed to detect interharmonics and can be compatible with the IEC standards. Simulations and the field results show the usefulness of the proposed methods.
In this paper we describe a session management system for setting up various collabora- tive classroom ,scenarios. The approach ,is addressing the additional workload ,of administrating classroom networks on the teacher, which is an important aspect for teachers' willingness to im- plement technology enhanced,learning in schools. The system facilitates preparation of classroom scenarios and the adhoc installation of networked collaborative sessions. We provided a graphical interface, which is usable for administration, monitoring, and for specification of a wide variety of different classroom ,situations with group work. The resulting graphical specifications are well suited to be re-used in the more formal learning design format IMS/LD; this is achieved by a auto- matable transformation of the scenarios to LD documents. Keywords: Collaborative classroom scenarios, lightweight classroom orchestration, learning de- sign, shared workspaces.
Sensing and processing of multimedia information is one of the basic traits of human beings. The development of digital technologies and applications allows the production of huge amounts of multimedia data. The rapidly decreasing prices for hardware such as digital cameras/camcorders, sound cards and the corresponding displays led to wide distribution of multimedia-capable input and output devices in all fields of the everyday life, from home entertainment to companies and educational organisations. Thus, multimedia information in terms of digital pictures, videos, and music can be created intuitively and is affordable for a broad spectrum of users.
NewsGrid
(2005)
Film archives—particularly those storing video material on all kinds of news items—are important information sources for TV stations. Each TV station creates and maintains its own archive by storing video material received via satellite and/or internet on tapes in analogue and/or digital form. It cannot be predicted in advance which of this archived material will actually be used. Thus all material received must be catalogued and stored. On average only a small percentage of the material stored is actually used. Due to the increase in data volumes the cost of maintaining such repositories and retrieving particular stored items has become prohibitive. To-day digital videos are increasingly replacing analogue material. Digital videos offer the advantage that the can be stored in distributed databases and then be transferred without loss of quality to the transmitting station. Such digital archives can be made accessible to many TV stations, thus spreading the maintenance cost. Individual stations can retrieve only the material they actually need for particular news casts. In this paper a grid architecture for distributed video archives for news broadcasts is proposed. A crucial aspect of such a grid approach is that advanced methods for retrieving data must be available.
Im vorliegenden Beitrag wird das Phasen-Differenz-Verfahren zur Frequenzmessung der durch Rauschen gestörten Signale vorgestellt. Es wird gezeigt, dass Frequenzausreißer bei Anwendungen dieses Verfahrens entstehen, auch wenn das Signal-zu-Rausch-Verhältnis ausreichend groß ist. Die Ursachen der Frequenzausreißer werden analysiert. Zur Korrektur wird ein Lösungsansatz vorgeschlagen. Im Vergleich mit anderen Verfahren kann das verbesserte Phasen-Differenz-Verfahren die Frequenz der durch Rauschen gestörten Signale mit größerer Genauigkeit und vertretbarem Rechenaufwand berechnen.