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  • Articles  (5,064)
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  • 1985-1989  (4,594)
  • 1940-1944  (470)
  • Electrical Engineering, Measurement and Control Technology  (5,064)
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  • 1
    Electronic Resource
    Electronic Resource
    Current distribution along a vertical earth electrode of finite length (1989)
    Springer
    Electrical engineering 72 (1989), S. 7-10 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Es wird ein Verfahren vorgestellt, mit dem die Stromdichte längs einer senkrechten Erdungselektrode begrenzter Länge berechnet werden kann, die als Senke für einen von einer benachbarten Punkt-Erdungselektrode ausgehenden Gleichstrom wirkt. Die Integro-Differentialgleichung wird formuliert, und eine numerische Lösungsmethode wird abgeleitet.
    Notes: Contents A method of calculation of the current density impressed along a vertical earth electrode of finite length by drained d.c. and by d.c. leaving nearby a point earth electrode is presented. The integro-differential equation is formulated and a numerical method for the solution is derived.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01573563
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  • 2
    Electronic Resource
    Electronic Resource
    Die Stoßdrehmomente bei symmetrischen und unsymmetrischen Kurzschlüssen in Asynchronmaschinen (1989)
    Springer
    Electrical engineering 72 (1989), S. 43-50 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents The transient phenomena in drives with cage induction motors and resiliently coupled loads after switching on the motor at rest and after three-phase short circuit or line-to-line fault during operation are handled in the paper. The calculation method is explained for the unsymmetrical connections regarding the numerical solution of the equations. Especially the switching torques in the shafts are of practical importance. The results of the calculations are demonstrated in detail for two examples of drives. It has been turned out, that line-to-line fault does not represent the worst case at all events.
    Notes: Übersicht Der Aufsatz behandelt die Ausgleichsvorgänge in Antrieben mit Asynchronmaschinen mit Käfigläufer und drehelastisch gekuppelter Arbeitsmaschine beim Einschalten im Stillstand sowie beim dreipoligen und zweipoligen Klemmenkurzschluß der laufenden Maschine. Das Berechnungsverfahren für die unsymmetrischen Schaltungen wird vorgestellt im Hinblick auf die numerische Lösung der Gleichungssysteme. Für die Praxis wichtig sind insbesondere die Stoßmomente in den Wellensträngen. Die Ergebnisse der Rechnungen werden an zwei Beispielantrieben ausführlich erläutert. Es zeigt sich, daß der zweipolige Kurzschluß keineswegs immer den gefährlichsten Störungsfall darstellt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01573568
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  • 3
    Electronic Resource
    Electronic Resource
    Smart SIPMOS: Der intelligente Leistungsschalter (1989)
    Springer
    Electrical engineering 72 (1989), S. 83-88 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents Especially for automotive and industrial electronics Siemens has developed the smart SIPMOS technology. This technology includes SIPMOS transistors and CMOS circuits. The first smart SIPMOS products are high side switches for the voltage range 5 V to 60 V.
    Notes: Übersicht Insbesondere für die Industrie- und Autoelektronik entwickelte Siemens die Smart SIPMOS-Technologie. Diese Technologie umfaßt SIPMOS-Transistoren und CMOS-Schaltungen für Spannungen bis 60V, monolithisch integrierbar auf einem Chip. Erste Smart SIPMOS-Bauelemente sind high side-Schalter für den Spannungsbereich 5 V bis 60 V.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01573641
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  • 4
    Electronic Resource
    Electronic Resource
    Untersuchungen und Erfahrungen mit abschaltbaren Leistungshalbleitern (1989)
    Springer
    Electrical engineering 72 (1989), S. 95-111 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents Presented are new turn-off semiconductor power devices (GTO, bipolar transistor, IGT, MOSFET, SIT and fast recovery diodes), which have changed decisively power electronics in all power ranges during the last years. Discussed are the switching behavior (turn-on and turn-off) and the applicable frequency range. PWM-inverters with different types of transistors are compared; here the IGT has the best properties. Gate driver circuits and gate power demand are given. Low-loss snubbers for GTOs are presented. Applications and development trends are shown.
    Notes: Übersicht Vorgestellt werden neue abschaltbare Leistungshalbleiter (GTO, bipolare Transistoren, IGT, MOSFET, SIT und schnelle Dioden), die in den letzten Jahren die Leistungselektronik in allen Leistungsbereichen entscheidend verändert haben. Diskutiert werden das Schaltverhalten (Ein- und Ausschalten) und der sich daraus ergebende Frequenzbereich. PWM-Wechselrichter mit 20 kHz Pulsfrequenz mit verschiedenen Transistortypen werden verglichen: hier hat der IGT die besten Eigenschaften. Steuergeneratorschaltungen und Steuerleistungsbedarf werden angegeben. Für GTOs werden verlustarme Beschaltungen erörtert. Anwendungen und Entwicklungstrends werden aufgezeigt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01573643
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  • 5
    Electronic Resource
    Electronic Resource
    Zur Bestimmung großer Diffusionslängen in Silizium-Wafern mit der SPV-Methode (1989)
    Springer
    Electrical engineering 72 (1989), S. 141-148 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents A new method for the determination of carrier diffusion length by proper evaluation of the Surface Photo Voltage (SPV)-technique is presented. To obtain better and more specific results, we take into account the carrier profile and the effective absorption of the specimen structure and use a sophisticated and very accurate measurement technique. Diffusion lengths up to the magnitude of the wafer thickness can be determined with an accuracy better than 25%.
    Notes: Übersicht Für die Bestimmung der Diffusionslänge mit der Surface-Photo-Voltage (SPV)-Methode wurde ein Auswerteverfahren entwickelt, das den Einfluß der Probenstruktur und der effektiven Lichtabsorption auf das Ladungsträgerprofil berücksichtigt. Es wird gezeigt, daß sich mit diesem Verfahren bei hoher Meßgenauigkeit noch Diffusionslängen, die der Waferdicke entsprechen, mit einer Genauigkeit 〉25% auflösen lassen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01573647
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  • 6
    Electronic Resource
    Electronic Resource
    Diffusionslänge der Minoritätsladungsträger — der wichtigste Parameter für Solarzellen (1989)
    Springer
    Electrical engineering 72 (1989), S. 149-155 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents The efficiency of a solar cell produced in crystalline silicon with an + p-structure depends on the effective diffusion length of the minority carriers in the base and in the emitter, on the recombination in the depletion layer and on the surface recombination rate. Possible optimizations of the different regions will be discussed. This results in a proposal for an optimal solar cell structure.
    Notes: Übersicht Der Wirkungsgrad einer Solarzelle aus kristallinem Silicium mitn + p-Struktur hängt im wesentlichen von der effektiven Diffusionslänge der Minoritätsladungsträger in der Basis und im Emitter, von der Rekombination in der Raumladungszone und von der effektiven Oberflächen-rekombinationsgeschwindigkeit ab. Es werden die Optimierungsmöglichkeiten dieser Gebiete aufgrund der unterschiedlichen Rekombinationseigenschaften diskutiert. Daraus resultiert ein Vorschlag für eine optimale Solarzellenstruktur.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01573648
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  • 7
    Electronic Resource
    Electronic Resource
    Der Transiente Elementar Dipol zur Beschreibung elektromagnetischer Vorgänge in Hochspannungsmeßkreisen (1989)
    Springer
    Electrical engineering 72 (1989), S. 183-194 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents The calibration of impulse voltage measuring systems is based on a system identification by unit-step response measurements. Regarding extended measuring systems, step-response distortions result from radiative coupling between the divider column and the measuring circuit. This paper describes a three dimensional field calculation method, allowing the modeling of high-voltage measuring circuits. Unlike the method of moments, geometrical theory of diffraction and hybride technique, the described method is based on the time domain model of the Transient Elementary Dipole TED. The paper demonstrates the calculation of the electromagnetic field in step-response measuring circuits, and the simulation of step-response measurements considering transient radiation effects.
    Notes: Übersicht In der Hochspannungsmeßtechnik treten bei der Sprungantwortmessung von räumlich ausgedehnten Spannungsteilern Signalverzerrungen auf, die von der elektromagnetischen Kopplung der Teilersäule mit der Zuleitung und dem Impulsgenerator herrühren. Nach einer kurzen Übersicht über bestehende Verfahren zur Berechnung transienter elektromagnetischer Felder wird ein dreidimensionales Zeitbereichsmodell zur Nachbildung von Meßkreisen der Hochspannungstechnik vorgestellt, der Transiente Elementar Dipol TED. Als Anwendungsbeispiele werden die Berechnung des elektromagnetischen Feldes in Sprungantwortmeßkreisen, sowie die Simulation von Sprungantwortmessungen unter Berücksichtigung des transienten Strahlungsfeldes vorgestellt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01577517
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  • 8
    Electronic Resource
    Electronic Resource
    Sensitivity approach to the optimal shape design of a magnetic pole contour (1989)
    Springer
    Electrical engineering 72 (1989), S. 27-32 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht In dem vorliegenden Aufsatz wurde ein neuer Algorithmus, der auf der Empfindlichkeit beruht, zum optimalen Gestaltentwurf herangezogen. — Die Dekomposition der Empfindlichkeitsmatrix gegen ihre Singularwerte und die Programmierung der kleinsten Distanzen [3] wurden verwendet, um den Richtungsvektor zu definieren. — Zwei Arten von den Randbedingungen wurden vorgegeben, um die mathematische Technik zu überprüfen und unerwünschte Konturen zu vermeiden. — Dieser Algorithmus wird anhand der Modifizierung eines Magnetpols veranschaulicht, um zur erwünschten magnetischen Feldverteilung im Luftspalt zu gelangen.
    Notes: Contents Based on the sensitivity approach a new algorithm for optimal shape design has been presented in this paper. The Singular Value Decomposition (SVD) of the sensitivity matrix and the Least Distance Programming (LDP) [3] have been used in order to define a direction vector. —Two types of side constraints have been imposed to control the mathematical technique and to avoid undesirable shapes. — The algorithm is illustrated by its application to modify the magnetic pole contour so that a desired magnetic field distribution in the air gap is obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01573566
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  • 9
    Electronic Resource
    Electronic Resource
    A three phase and a quadrature-phase slip-ring model for saturated smooth-air-gap electrical machines (1989)
    Springer
    Electrical engineering 72 (1989), S. 59-68 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Das dreiphasen und zweiphasen Schleifringläufermodell für elektrische Zylinderläufermaschienen wird nachfolgend bei Berücksichtigung der Sättigung des Hauptflusses behandelt. Bei Verwendung der Raumzeigertheorie werden die Impedanz-Matrizen für die zwei modelle abgeleitet. Eine genaue Auswertung wurde durchgeführt und es wird gezeigt, daß abhängig von der Sättigung Unsymmetrien entstehen. Unter linear magnetischen Bedingungen führen die neu entwickelten Gleichungen zu den wohlbe-kannten Gleichungen, die in der allgemeinen elektrischen Maschinentheorie benutzt werden.
    Notes: Contents The three-phase model and quadrature-phase slip-ring model for smooth-air-gap electrical machines are presented, if saturation of the main flux paths is considered. By utilizing space-vector theory, the impedance matrices for the two models are derived. A detailed analysis is performed and it is shown that due to saturation, anisotropy will arise, which leads to extra elements and coupling in both impedance matrices. Under linear magnetic conditions the newly developed equations lead to the well-known equations used in generalized electrical machine theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01573570
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  • 10
    Electronic Resource
    Electronic Resource
    Einsatz von Protonenbestrahlung in der Technologie der Leistungshalbleiter (1989)
    Springer
    Electrical engineering 72 (1989), S. 133-140 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents With proton irradiation, recombination centres in well defined depths of silicon devices can be formed. In this way a new degree of freedom for optimizing the switching behaviour of bipolar silicon devices is obtained. — Proton irradiation enables reduced switching losses of GTO thyristors and improved recovery behaviour of power diodes. If the hydrogen implantation correlated donor formation is not tolerable, He-irradiation may be used.
    Notes: Übersicht Durch Protonenbestrahlung können Rekombinationszentren in Siliziumbauelementen in definierter Tiefe erzeugt werden. Dadurch ergibt sich ein neuer Freiheitsgrad für die Optimierung bipolarer Bauelemente. — Durch den Einsatz von Protonenbestrahlung können bei GTO-Thyristoren geringere Schaltverluste und bei Dioden günstigeres Kommutierungsverhalten erzielt werden. Falls die mit der Wasserstoffimplantation verbundene Bildung energetisch flacher Donatoren nicht zulässig ist, könnte stattdessen He-Bestrahlung eingesetzt werden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01573646
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  • 11
    Electronic Resource
    Electronic Resource
    Analysis of the commutation processes for PAM inverter having one LC-commutation circuit only (1989)
    Springer
    Electrical engineering 72 (1989), S. 175-182 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht In dieser Arbeit wird die Analyse der Kommutierungsprozesse und der Entwurf des Zwangskommutierungskreises für den PAM-Wechselrichter, der nur einen LC-Kommutierungskreis hat, wiedergegeben. Gleichfalls wird ein neues Steuerungsverfahren mit Pulsamplituden-modulation vorgestellt, das die Harmonischen von kleiner Ordnung, bis zur 17., des Statorstromes eliminiert. Auf der Grundlage dieses Prinzips erhält man eine höhere Stabilität in der dynamischen Arbeitsweise der Maschine.
    Notes: Contents In this paper, the analysis of the commutation processes and design of the forced commutation circuit is presented for the PAM inverter with having one LC-commutation circuit only and new pulse amplitude modulation control technique are described for this inverter, which eliminate the stator current harmonics of an order lower than 17th. Based on this principle resulting in a higher stability of the machine operation in the dynamic regime.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01577516
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  • 12
    Electronic Resource
    Electronic Resource
    Transientes Betriebsverhalten eines 2×3strängigen Stromrichtermotors mit Massivläufer (1989)
    Springer
    Electrical engineering 72 (1989), S. 205-217 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents In part 1 the mathematical model of a synchronous machine with solid iron rotor and two separate three-phase windings is described. Part 2 illustrates the modeling of the twelve-pulse inverter and explains the mathematical way and the programming of coupling subsystems. A final comparison between measurement and calculation shows a satisfactory correspondence. So it is possible to take into account eddy currents in the solid iron when simulating the transient behaviour of a converter-fed synchronous machine.
    Notes: Übersicht Teil 1 befaßte sich mit der mathematischen Modellbildung der 2×3strängigen Synchronmaschine mit Massivläufer. Im Teil 2 wird gezeigt, wie der 12pulsige Wechselrichter nachgebildet werden kann, und wie insbesondere das Problem der Kopplung der Teilsysteme mathematisch und programmtechnisch zu lösen ist. Ein abschließender Vergleich von Meßergebnissen mit den Ergebnissen einer Simulationsrechnung zeigt eine gute Übereinstimmung. Es ist somit möglich, die bei der Stromrichterspeisung im Rotor der Synchronmaschine auftretende elektrische Wirbelströmung bei der digitalen Simulation des transienten Betriebsverhaltens zu berücksichtigen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01577519
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  • 13
    Electronic Resource
    Electronic Resource
    Optimal working self-commutated reactive power compensator with inductive store (1989)
    Springer
    Electrical engineering 72 (1989), S. 233-237 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht In der Arbeit wird ein neuer Blindleistungsstromrichter mit induktivem Speicher vorgeschlagen, der eine höhere Wirksamkeit aufweist. Durch diesen Stromrichter erhält man Blindströme mit einem reduzierten Oberschwingungsgehalt durch einen Kompensationskreis mit 12 Pulsen und der den Vorteil aufweist, einfachere Zwangskommutierungskreise zu benötigen.
    Notes: Contents A new high performance reactive power compensator with inductive store is proposed, which permit to obtain reactive currents with reduced content in high harmonics by addopting a 12-pulse compensation scheme. This converter presents te advantage of a simpler turning-off circuits of the main thyristors, as compared to the version presented in the former work.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01573846
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  • 14
    Electronic Resource
    Electronic Resource
    Anisotrope Thyristorbrücken (1989)
    Springer
    Electrical engineering 72 (1989), S. 263-275 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents In the present paper, the effects of unbalanced firing-angle control on stationary terminal currents of threephase two-way converter bridges are calculated, using the theory of the symmetrical components. Analytical equations are given to determine the firingangle unbalance from measured irregularities of the terminal currents. Furthermore a control system for compensation of voltage unbalance in weak networks fed by HVDC-trans-mission is elaborated. This control system works with firing angles of the inverter station only changed by a minimum.
    Notes: Übersicht In der vorliegenden Arbeit werden die Auswirkungen von Steuerungsunsymmetrien auf den stationären Klemmenstrom sechspulsiger Thyristorbrücken mit der Theorie der symmetrischen Komponenten rechnerisch verfolgt. Analytische Gleichungen zur Bestimmung der Steuerungsunsymmetrie aus gemessenen Irregularitäten des Klemmenstromes werden angegeben. Des weiteren wird eine Symmetrierungsregelung HGÜ-gespeister Netze geringer Kurzschlußleistung entwickelt, die mit minimalen Zündwinkeländerungen des Wechselrichters auskommt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01573849
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  • 15
    Electronic Resource
    Electronic Resource
    Analysis of the magnetic field in a permanent-magnet motor, carried out by the finite element method (1989)
    Springer
    Electrical engineering 72 (1989), S. 1-5 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Es wird die Analyse des magnetischen Feldes einer elektrischen Maschine mit permanenten Magneten dargestellt und erläutert. Dabei wird die Methode der finiten Elemente benutzt, und zwar bei Verwendung des entsprechenden Funktionals. Die Resultate können für die analyse des magnetischen Feldes anderer ähnlicher Maschinen Anwendung finden.
    Notes: Contents An analysis has been made of the magnetic field in a permanent-magnet motor by applying the finite element method, using an adequate functional. The results obtained may be applied for analyzing the magnetic field in similar motors of a different design.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01573562
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  • 16
    Electronic Resource
    Electronic Resource
    Berechnung der elektrischen Kapazität von Elektrofiltern mit analytischen und numerischen Methoden (1989)
    Springer
    Electrical engineering 72 (1989), S. 377-380 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents The capacitance of electrostatic precipitators determines charging effects of pulsed energization, filtering of de power supplies and energy transfer during sparking. Whereas, for a specific geometry, this capacitance can be readily computed with today's field codes, no functional velationship is available relating it to various precipitator parameters, e.g. wire radius, duct spacing, distance of corona wires. Therefore, this paper presents a new analytical approximation formula permitting fast capacitance calculations. The obtained results agree very well with numerically computed precise values.
    Notes: Übersicht Die elektrische Kapazität eines Elektrofilters ist wegen ihrer Rückwirkung auf Impulsspannungsversorgungen, ihrer Gläuttungswirkung bei welligen Gleichspannungsversorgungen, sowie ihres Einflusses auf den Energieumsatz bei Überschlägen ein wichtiges Kriterium für die Aufteilung großer Filter in einzelne Sektionen. Mit digitalen Rechenprogrammen lassen sich zwar Kapazitäten für jeden Einzelfall berechnen, allgemeine Aussagen über den Einfluß verschiedener Parameter erfordern jedoch zahlreiche Parameterstudien. Dieser Beitrag verdeutlicht im ersten Teil die Problematik der Kapazitätsberechnung in Elektrofiltern am Beispiel paralleler Drähte. Im zweiten Teil wird eine analytische Näherung vorgestellt, die den Einfluß der unterschiedlichen Parameter wie Gassenabstand, Drahtradius und Sprühdrahtabstand zu berücksichtigen gestattet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01573755
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  • 17
    Electronic Resource
    Electronic Resource
    Numerical computation of loss distribution in transformer cores (1989)
    Springer
    Electrical engineering 72 (1989), S. 389-393 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Eine Methode für die Berechnung der Verteilung von Transformatorkernflüssen und-verlusten wird beschrieben. Besondere Aufmerksamkeit wird der Untersuchung des Einbusses des Luftspalts im Schnittpunkt der Schenkel- und Jochbieche auf die Verteilung der Verluste geschenkt. Im Vergleich mit Ergebnissen von Modellmessungen gibt die munerische Berechnung der Verluste sehr genaue Ergebnisse muter der Voraussetzung, daß die magnetische Charakteristil, des Luftspalts richtig einbezogen wird.
    Notes: Contents A numerical method for computation of flux and loss distribution in transformer cores is described. Special attention has been given to the investigation of the influence of leg and yoke joint-gap connections on the distribution of losses. In comparison with results of measurements on models, numerical computation of the distribution of losses provides results that are quite accurate, provided that the magnetic characteristic of the joint-gap has been correctly taken into account.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01573757
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  • 18
    Electronic Resource
    Electronic Resource
    Einfluß der Luftspaltweite auf die Verluste schnellaufender Asynchronmaschine mit Käfigläufer (1989)
    Springer
    Electrical engineering 72 (1989), S. 427-434 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents The additional losses of squirrel cage induction motors can be reduced considerably by increasing the air gap. A calculation method is presented how to determine the power losses which are influenced by air gap length. The results are verified by measurements of three various motors with a power output between 10 and 50 kW. In operation with inereased stator frequency a reduction of total losses ranging up to 32 p.u. is achieved. This is valid for operation with sinusoidal voltage. For supply by frequency inverters with nonsinusoidal output the total losses are reduced about the same absolute amount.
    Notes: Übersicht Die Zusatzverluste von asynchronen Käfigläufermotoren können durch Vergrößerung der Luftspaltweite beträchtlich vermindert werden. Es wird ein Berechnungsverfahren zur Bestimmung der luftspaltabhängigen Verluste vorgestellt. Die Ergebnisse wurden durch Messungen an drei verschiedenen Motoren im Leistungsbereich zwischen 10 und 50 kW überprüft. Bei Betrieb mit erhöhter Ständerfrequenz wird eine Reduzierung der Gesamtverluste um bis zu 32% erzielt. Dies gilt bei Betrieb der Motoren mit sinusförmiger Spannung. Bei Speisung über Frequenzumrichter mit nichtsinusförmigen Ausgangsgrößen reduzieren sich die Gesamtverluste um den gleichen absoluten Betrag.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01573761
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    Some remarks on the gap-field in electromagnetic gliders (1989)
    Springer
    Electrical engineering 72 (1989), S. 319-325 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Ein einfaches Modell des Spaltfeldes der linearen Asynchronmaschine wird angegeben, welches der strengen Behandlung mittels der Einstein-Minkowskischen Elektrodynamik zugänglich ist.
    Notes: Contents A simplified model of the gap-field of a linear induction machine is presented; the model lends itself to analysis within the framework of the Einstein-Minkowski lectrodynamics.
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    Calculation of propulsion forces in EDS-MAGLEV transport systems with superconducting coils (1989)
    Springer
    Electrical engineering 72 (1989), S. 333-339 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Im Artikel wird ein analytisch-dreidimensionales Verfahren beschrieben, das die Berechnung der Antriebskraft erlaubt, die bei überschnellen Beförderungssystemen wie EDS-MAGLEV durch lineare Langstator-Synchronmotoren entsteht, wobei Supraleitungsspulen sowohl zur Motorerregung als auch zur magnetischen Levitation des Fahrzeuges verwendet werden. Das Verfahren berücksichtigt die endliche Spulendicke und geht aus von der Änderung der magnetischen Energie, die in den Anker- und Erregerwicklungen (Zylinder- sowie Wellenwicklungen) des Motors gespeichert ist. Die Werte der Antriebskraft, die durch die Anwendung dieses Verfahrens auf einen in Japan ausgeführten Experimentalprototyp ermittelt werden, weisen eine gute Übereinstimmung mit den experimentellen Werten auf.
    Notes: Contents The paper describes an analytical three-dimensional method which allows the determination of the propulsion force produced by air core long stator linear synchronous motors in EDS-MAGLEV transport systems, using super-conducting coils both for motor field winding and for vehicle levitation. The method, which allows to take into account the finite thickness of the coils, is based on the variation of the magnetic energy stored in the field and armature (over-lapped or non-overlapped) windings of the motor. The application of the method to an experimental Japanese prototype gives good concordance with the experimental data.
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    URL: http://dx.doi.org/10.1007/BF01573714
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    Komplexe Größen in der Elektrotechnik (1989)
    Springer
    Electrical engineering 72 (1989), S. 407-414 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents Complex quantities are extremely useful for the description of some physically technical interrelations in electrical engineering. The common mathematical formatism, however, misleads into disregarding the differences between the individual ranges of application and into using unsuitable terms. The attempt is made to physically define the individual possibilities of employing the complex quantities and to find convenient names for them.
    Notes: Übersicht Komplexe Größen haben sich für die Beschreibung von gewissen physikalisch-technischen Zusammenhängen in der Elektrotechnik als besonders nützlich erwiesen. Der gemeinsame mathematische Formalismus verleitet jedoch zur Mißachtung der inhaltlichen Unterschiede in den einzelnen Anwendungsgebieten und zur Einführung von zahlreichen unzutreffenden Bezeichnungen. Es wird nun der Versuch gemacht, die einzelnen Anwendungsmöglichkeiten der komplexen Größen physikalisch zu definieren und mit entsprechenden Namen zu versehen.
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    An antenna array synthesis technique by the help of Chebyshev polynomials (1989)
    Springer
    Electrical engineering 72 (1989), S. 435-441 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht In der vorliegenden Arbeit wird eine Methode für den Entwurf von strahlungsgekoppelten Drahtstrukturen mit vorgegebener Anzahl der Nebenzipfel und Nebenkeulendämpfung behandelt. Das Richtdiagramm wird als Produkt eines Chebyshevschen Polynomsn-ten Grades mit einem Polynom ersten Grades angesehen. Außerdem wird mit Hilfe der Momentenmethode die Strahlungscharakteristik einer Drahtantenne in Form einer aus Punktquellen bestehenden strahlenden Linie angegeben. Dadurch wird der Entwurf auf letztere zurückgeführt. Mehrere Beispiele deuten die Anwendbarkeit dieser Methode an.
    Notes: Contents A method for synthesis of antenna arrays with a given number of sidelobes and sidelobe levels is discussed. The pattern is given as a multiplication of a Chebyshev polynomial of nth degree with the one of first degree. The radiation pattern of a wire antenna in a form similar to that of an array with point sources is also given by the method of moments. So the synthesis procedure can be reduced. Several examples show the applicability of the method.
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    Erzeugung von Lösungsklassen für feldtheoretische Zweimedienprobleme aus speziellen Dirichlet- und Neumann-Lösungen (1989)
    Springer
    Electrical engineering 72 (1989), S. 219-223 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents Arrangements with only piecewise homogeneous medium are quite common in field theory. A method is presented here which fits the quite involved boundary conditions by combining much easier obtained Dirichlet and Neumann solutions. No restrictions must be imposed on the shape of the boundary surface. The procedure reveals the shared background of electrical fields, magnetic fields produced by currents and currentflow fields.
    Notes: Übersicht Feldberechnungen bei nur stückweise homogenem Medium verlangen die Erfüllung komplizierter Feldlinienbrechungsgesetze an den Mediengrenzen. Die hier vorgeschlagene Methode löst das Problem durch Zurückführung auf viel einfachere Dirichlet- und Neumann-Randbedingungen. Dabei muß die Mediengrenze keine spezielle Form haben, so daß allgemeine Aufgaben einbezogen sind. Es werden auch die Gemeinsamkeiten und die vorzunehmenden Modifikationen erklärt, die notwendig werden, wenn statt elektrischer Felder Magnetfelder von Strömen oder Stromdichtefelder zu berechnen sind.
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    Field distribution and eddy-current losses in coupled cylindrical shells, as in a turbogenerator rotor with a grooved surface (1989)
    Springer
    Electrical engineering 72 (1989), S. 251-262 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Die Berechnung der Wirbelströme in der gerillten Rotoroberfläche eines Turbogenerators führt allgemein auf das Problem, Wirbelströme in gekoppelten Kreiszylinderschalen zu berechnen. Die Theorie läßt sich dreidimensional aufbauen und formulieren, wenn man von dem praktisch wichtigen Sonderfall ausgeht, daß Felder und Ströme zeitlich stationär verlaufen.
    Notes: Contents Calculation of the eddy-currents which occur in the grooved surfaces of turbogenerators generally leads to the problem of calculating the eddy-currents in coupled cylindrical shells. The theory can be built up and formulated by starting with the important special practical case in which the fields and currents have reached a steady-state condition.
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    Untersuchung zur magnetischen Kopplung von Längs- und Querachse durch Sättigung am Beispiel der Reluktanzmaschine (1989)
    Springer
    Electrical engineering 72 (1989), S. 277-282 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents Iron-saturation in synchronous machines causes magnetic cross-coupling of the flux pathes of direct and quadrature axis. This coupling effect is investigated by means of numerical field analysis using a reluctance machine for testing. The comparison with experimental results shows, that only by considering the cross-coupling effect useful results of calculation can be obtained.
    Notes: Übersicht Die Eisensättigung bewirkt bei Synchronmaschinen eine magnetische Kopplung zwischen den Flußpfaden der Längs- und der Querachse. Anhand einer Reluktanzmaschine wird diese Kopplung mit der Hilfe numerischer Feldberechnung untersucht. Der Vergleich mit Meßergebnissen zeigt, daß nur mit Berücksichtigung der magnetischen Kopplung bei hohen Sättigungen brauchbare Berechnungsergebnisse erhalten werden können.
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    Field diffusion in magnetic circuits containing moving conducting parts (1989)
    Springer
    Electrical engineering 72 (1989), S. 11-18 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Der Beitrag beschreibt eine numerische Methode zur Berechnung des transienten elektromagnetischen Feldes in magnetischen Kreisen, die bewegte leitende Teile enthalten. Das Verfahren ermöglicht die Bestimmung der Feldverteilung, wenn nur die speisende Spannung bekannt ist. Dabei wurden die Gleichungen des elektromechanischen Gleichgewichts herangezogen. Das Verfahren fand bei einer Analyse des transienten Verhaltens eines schnellen elektromagnetischen Aktuators Anwendung.
    Notes: Contents The paper describes a numerical method of calculating the transient electromagnetic field in magnetic circuits containing moving conducting parts. The procedure allows determining the field distribution if only the supply voltages are known. The equations of the converter's electro mechanical equilibrum have been taken into account. The procedure has been employed for an analysis of transient states in a fast-acting electromagnetic actuator.
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    Reliability modelling interactive techniques of power systems including wind generating units (1989)
    Springer
    Electrical engineering 72 (1989), S. 33-41 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Die stochastische Energiedarbietung unterscheidet Windgeneratoren von konventionellen Generatoren und ist bei Zuverlässigkeitsuntersuchungen zu beachten. Hier wird das System in mehrere Teilsysteme zerlegt, deren eines die konventionellen Einheiten zusammenfaßt, während die übrigen den Windenergiekonvertern zugeordnet sind. Für jedes Teilsystem wird ein Modell der Verfügbarkoit gebildet, und daraus werden Erwartungswerte der Ausfallzeiten berechnet. Die Methode wird anhand einer ausgeführten Energieverteilung auf einer griechischen Insel dargestellt.
    Notes: Contents Interactive computational techniques for reliability evaluation of power systems including wind generating units are presented. The fluctuating nature of energy produced by wind generators has a different effect on the overall system reliability than conventional units. The overall power system is divided into a subsystem containing the conventional units and into several subsystems containing the wind generating units. For each of these subsystems a generation availability model is built and the obtained models are combined to evaluate the loss of load expectation index for the time period of study. The developed methodology is illustrated by the analysis of a system based on a real power distribution system existing in a Greek island. Although the paper concentrates on wind energy sources, the general configuration of the developed techniques is applicable to generation systems containing any type of intermittent sources such as solar energy sources.
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    Der feldgesteuerte Thyristor (FCTh) — ein Leistungsschalter mit weitgehend optimalen Eigenschaften für den Einsatz im oberen Leistungsbereich (1989)
    Springer
    Electrical engineering 72 (1989), S. 69-82 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents Due to their principle of operation, FCThs (FTDs, SIThs) are among the best candidates for switching high currents and voltages: They conduct like diodes, are blocked by field effect and require drive current only during turn-on and turn-off.— Two main innovations were necessary to make this potential accessible: By means of the recessedgate-(Verigrid)-technology the device's control finger width, height, doping and contacting can be optimized independently, and by an extremely low inductive drive fast and homogeneous turn-off is obtained. — With small technological effort we have realized FCThs exhibiting features which come close of the theoretical limits of bipolar silicon devices. Therefore it is likely that the FCTh will make possible snubberless circuits in the near future even at highest power level.
    Notes: Übersicht Das Funktionsprinzip prädestiniert den FCTh (alias FTD, SITh) für das Schalten großer Ströme und Spannungen: FCThs leiten wie Dioden, werden durch Feldeffekt blockiert und benötigen nur zum Umschalten Ansteuerenergie. — Doch zwei grundlegende Innovationen waren zur Erschließung dieses Potentials erforderlich: Die Recessed-Gate-(Verigrid)-Technologie, damit Breite, Höhe, Dotierung und Kontaktierung der Steuerfinger der FCThs unabhängig voneinander optimiert werden können und eine extrem niederinduktive Ansteuerung zum schnellen und homogenen Ausschalten der FCThs.— So haben wir unter geringem technologischem Aufwand Bauelemente mit Eigenschaften realisiert, die den theoretischen Grenzen bipolarer Si-Schalter sehr nahe sind. Snubberfreie Schaltungen dürften damit auch in der höchsten Leistungsklasse in Kürze realisierbar sein.
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    Vergleich verschiedener planarer Passivierungstechniken für Halbleiterleistungsbauelemente (1989)
    Springer
    Electrical engineering 72 (1989), S. 89-94 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents Different passivation techniques for planar semiconductor power devices with blocking voltages of 1600 V are studied using two-dimensional numerical simulations.
    Notes: Übersicht Für die Entwicklung einer optimalen Planar-passivierung von Halbleiterleistungsbauelementen mit Sperrspannungen von 1600 V wird ein Vergleich verschiedener Strukturen anhand zweidimensionaler numerischer Simulationen durchgeführt.
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    Dynamischer Avalanche beim Abschalten von GTO-Thyristoren und IGBTs (1989)
    Springer
    Electrical engineering 72 (1989), S. 113-123 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents The enhancement of the electric field by free carriers and the associated avalanche generation (dynamical avalanche) during turn-off of GTO-thyristors and IGBTs are studied on the base of one-dimensional numerical simulations. The snubberless element is assumed to switch an inductive load. For the usual gate turn-off of GTOs as well as for the GTO-cascode turn-off, which in its internal mode of operation agrees with the IGBT switch-off process, the field enhancement by free carriers amounts to 20 to 30% in cases discussed in the paper. This results in a reduction of the safe operating area and a significant enhancement of switch-off losses for current and voltage values not far away from the SOA limit. Compared with the space charge of holes obtained from their current and drift velocity, however, the dynamical field enhancement is small. This is due to a high degree of compensation of the hole charge in the space charge layer by electrons, which after the termination of injection from then emitter (or source, respectively) are generated by the dynamical avalanche. In this way the avalanche process limits and controls itself. The self-controlled dynamical avalanche governs largely the sweepingout of carriers and voltage build-up during the storage phase of the GTO-cascode and IGBT turn-off process.
    Notes: Übersicht Die Felderhöhung durch freie Ladungsträger und die dadurch ausgelöste Avalanche-Generation (dynamischer Avalanche) beim Abschalten von GTO-Thyristoren und IGBTs werden mit Hilfe eindimensionaler Simulationsrechnungen untersucht. Mit dem snubberlosen Schaltelement wird eine induktive Last geschaltet. Sowohl bei der üblichen GTO-Abschaltung als auch bei der GTO-Kaskodenabschaltung, die im inneren Funktionsablauf mit der IGBT-Abschaltung übereinstimmt, beträgt die Feldüberhöhung in den dargestellten Fällen 20 bis 30%. Dies führt zu einer Verkleinerung des sicheren Arbeitsbereichs und einer erheblichen Vergrößerung der Abschaltverluste für Strom-und Spannungswerte, die nicht weit von der SOA-Grenze entfernt liegen. Verglichen mit der Raumladung der Löcher, die sich aus deren Strom und Driftgeschwindigkeit ergibt, ist die dynamische Feldüberhöhung jedoch gering. Dies beruht auf einer weitgehenden Kompensation der Löcher in der Raumladungszone durch Elektronen, die nach Beendigung der Injektion aus demn-Emitter (bzw. dem Source) durch den dynamischen Avalanche generiert werden. Letzterer begrenzt und steuert sich auf diese Weise selbst. Der selbstkontrollierte dynamische Avalanche bestimmt weitgehend das Ausräumen der Ladungsträger und den Spannungsaufbau während der Speicherphase der GTO-Kaskodenund IGBT-Abschaltung.
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    Transformation method for electromagnetic wave problems with moving boundary conditions (1989)
    Springer
    Electrical engineering 72 (1989), S. 165-173 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Eine Methode zur Lösung von Anfangs-Randwert-Problemen der Wellengleichung mit bewegten Randbedingungen wird gegeben, welche die Wellengleichung für das Gebiet mit bewegter Grenzfläche in eine form-invariante Wellengleichung für ein Gebiet mit ruhender Grenzfläche umformt. Zwei Arten von Transformationen werden gefunden, welche sich auf zeitlich (1) expandierende und (2) schrumpfende Gebiete beziehen. Als Anwendung wird die Kompression von Mikrowellen in einem eindimensionalen Hohlraum 0≦x≦s(t) mit einem festen Liner beix=0 und einem nach Innen bewegten Liner beix=s(t) analytisch behandelt. Es wird gezeigt, daß sich große Mengen von Mikrowellen-Energie in der Endphases(t)→0 der Kompression mit Hilfe eines durch Explosivstoffe angetriebenen Kupfer Liners ( $$\left| {(\dot s(t)} \right| 〉 10^3 m/s$$ ) erzeugen lassen, für Zeiten von der Größenordnung der elektromagnetischen Diffusionszeitτ D =μσd 2∼10-2s. Derartige Mikrowellen-Kompressionen erfolgen quasi-statisch bei nicht-relativistischen Liner Geschwindigkeiten, $$\left| {\dot s(t)} \right| \ll c$$ .
    Notes: Contents A method for the solution of initial-boundary-value problems of the wave equation with moving boundary conditions is presented, which transforms the wave equation for the region with moving boundary into a form-invariant wave equation for a region with fixed boundary. Two kinds of transformations are found which refer to regions (1) expanding and (2) contracting with (increasing) time. As an application, the compression of microwaves in a one-dimensional cavity 0≦x≦s(t) with fixed liner atx=0 and an inward moving liner atx=s(t) is treated analytically. It is shown that large amounts of microwave energy can be generated in the final compression stages(t)→0 with the help of a copper liner driven by explosives ( $$\left| {(\dot s(t)} \right| 〉 10^3 m/s$$ ), for times of the order of the electromagnetic diffusion time,τ D =μσd 2∼10-2s. Such microwave compressions proceed quasi-statically for non-relativistic liner velocities, $$\left| {\dot s(t)} \right| \ll c$$ .
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    Die Stoßdrehmomente bei symmetrischen und unsymmetrischen Kurzschlüssen in Asynchronmaschinen (1989)
    Springer
    Electrical engineering 72 (1989), S. 224-224 
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    Topics: Electrical Engineering, Measurement and Control Technology
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    Synthesis of magnetic fields by optimisation of the shape of current areas (1989)
    Springer
    Electrical engineering 72 (1989), S. 293-300 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Die Arbeit behandelt eine neue Methode zur Synthese von zweidimensionalen Magnetfeldern. Das vorgeschlagene Verfahren ermöglicht die Berechnung der optimalen Form von Gleichstromgebieten bei der Erzeugung vorgegebener Magnetfelder. Die Grundidee des Berechnungsverfahrens basiert auf der Anwendung einer modifizierten Gradientmethode zur Lösung von nichtlinearen, überbestimmten Gleichungssystemen, die mit der Methode der finiten Elemente entwickelt wurden. Für die Synthese eines bereichsweise homogenen Magnetfeldes werden die Ergebnisse der numerischen Berechnungen dargestellt.
    Notes: Contents The paper deals with a new method for the synthesis of two-dimensional magnetic fields. The proposed algorithm makes it possible to determine the optimal structure of constant-current areas by generation of the required magnetic field distribution. The main idea of this algorithm is based on the application of a modified gradient method for solving the overdetermined, nonlinear system of algebraic equations obtained by the finite element method. Numerical calculations performed in examples demonstrate the application of the proposed method for the synthesis of the uniform magnetic field.
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    Development of the Boundary Element Method aimed at magnetic field computation of an induction motor (1989)
    Springer
    Electrical engineering 72 (1989), S. 309-317 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Die Rand-Elemente-Methode wird in Zusammenhang mit der Methode der finiten Elemente zur Berechnung des magnetischen Feldes eines Asynchronmotors im Leerlauf verwendet. Die Eisensättigung der Motorblechpakete wurde in den Berechnungen berücksichtigt.
    Notes: Contents The Boundary Element Method (BEM) designed in special way is employed in conjunction with the Finite Element Method (FEM) to calculate the magnetic field of an induction motor at no-load. The B−H characteristic of the motor laminations is taken into account.
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    Induzierte Wirbelströme in einem dünnen leitenden Band bei beliebiger Form der erregenden Leiterschleife (1989)
    Springer
    Electrical engineering 72 (1989), S. 301-308 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents Using MATHIEU functions, the magnetic scalar potential of a spatial coil in elliptic cylinder coordinates are studied analytically in this paper. Provided the strip-line is thin compared to the skin depth the induced eddy currents can be determined by the aid of the scalar stream function, the coefficients of which are resulting from an infinite linear equation system. Using a lucid example of a coil of simple shape, the eddy current distribution and the stream lines are represented graphically for different points of time.
    Notes: Übersicht Es wird zunächst das magnetische Skalarpotential einer räumlichen Leiterschleife in elliptischen Zylinderkoordinaten durch Entwicklung nach MATHIEUschen Funktionen angegeben. Unter der Voraussetzung großer Eindringtiefen im Vergleich zur Dicke des Bandleiters können die induzierten Wirbelströme durch die skalare Stromfunktion beschrieben werden, für deren Lösungskoeffizienten unendliche lineare Gleichungssysteme aufgestellt und numerisch ausgewertet werden. Am Beispiel einer einfachen Leiterschleifenanordnung wird die Stromdichte im Bandleiter sowie der Verlauf der Stromlinien zu verschiedenen Zeitpunkten grafisch dargestellt.
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    Earthing impedance of cylindrical conductor in a two-layer soil (1989)
    Springer
    Electrical engineering 72 (1989), S. 349-355 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Die Arbeit beschäftigt sich mit der Bestimmung Erdausbreitungsimpedanz von zylindrischen Elektroden. Im Fall von aus zwei Schichten bestehendem Erdboden wird die Abhängigkeit der Wirkung der Wirbelströme von der spezifischen Leitfähigkeit bzw. von der Schichtdicke untersucht. Die Lösung der Helmholtz'schen Differentialgleichung, die die magnetische Feldstärke beschreibt, erfolgt durch die Globalelementmethode der Variationsrechnung. Die Erfüllung der Dirichlet'schen Randbedingungen an der Oberfläche der Erde und entlang derz-Achse, sowie die Erfüllung der Kontinuitätsbedingungen an den Schichtgrenzen ist durch die Anwendung derR-Funktionen gesichert.
    Notes: Contents The paper deals with the determination of the earthing impedance of a cylindrical electrode modelling an earthing system of a transmission tower. Assuming a soil of two layers, the effect of the eddy currents in the soil is investigated with the conductivity and the thickness of the layers varied. The solution of the Helmholtz equation given for the magnetic field intensity is obtained by a global variation method. The satisfaction of Dirichlet boundary conditions on the surface of earth and along thez-axis as well as of the continuity conditions on the interface of the layers is ensured with the aid ofR-functions.
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    Difference method in integral technique in field analysis of doubly salient switched reluctance motor (1989)
    Springer
    Electrical engineering 72 (1989), S. 381-387 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Der Artikel betrifft die auf die Verteilung des elektromagnetischen Feldes gestützte Berechnungsmethode des Drehmoments eines geschalteten Doppelreluktanzmotors. Die magnetischen Berechnungen wurden nach der Differenzenmethode in der integralen Auffassung durchgeführt. Die Analyse der Verteilung des elektromagnetischen Feldes wurde für einen Modellmotor bei Berücksichtigung der nichtlinearen Eigenschaften der Medien dargestellt. Die Momentenkennlinie des Reluktanzmotors zeigt die Abhängigkeit des Drehmoments von der Rotorstellung.
    Notes: Contents The paper presents a method of calculation of the switched reluctance motor torque on the basis of the calculated electromagnetic field distribution while the difference method in integral technique has been employed. The analysis of the electromagnetic field distribution has been performed for the model motor, with the effect of magnetic nonlinearity of the medium taken into account. The obtained SR motor torque curves gives evidence of the torque as a function of the rotor position.
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    Zum Einfluß der Streufeldkopplung auf die magnetischen Eigenschaften und den Wirkungsgrad handelsüblicher Transformatorkerne aus kornorientierten Silizium-Eisen-Elektroblechen (1989)
    Springer
    Electrical engineering 72 (1989), S. 395-405 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents From a survey of the important stray-field sources of a grain oriented M-shaped silicon-iron sheet follows that only the stray field at the air gap can give a remarkable contribution to the stray-field coupling. The influence of this air-gap stray fields on the magnetization structure and the magnetization reversal of a neighbouring sheet is investigated. From the shielding effect of the neighbouring sheet in dependence on the excitation in an applied field some statements concerning the influence of the stray-field coupling on the energy loss and the efficiency of the complete transformer core consisting of several sheets are derived and some proposals for the improvement of the efficiency during voltage transformation are given.
    Notes: Übersicht Aus einem vergleichenden Überblick über die wesentlichen Streufeldquellen eines M-Schnitt-Bleches aus kornorientiertem Silizium-Eisen folgt, daß nur das Luftspaltfeld einen merklichen Anteil zur Streufeldkopplung liefern kann. Der Einfluß dieses Luftspalt-Streufeldes auf die Magnetisierungsstruktur und den Ummagnetisierungsvorgang in einer benachbarten Blechlage wird untersucht. Aus einer Diskussion der abschirmenden Wirkung des benachbarten Bleches in Abhängigkeit von der Aussteuerung folgen Aussagen über den Einfluß der Streufeldkopplung auf die Energieverluste und den Wirkungsgrad des kompletten Transformatorkernes aus mehreren Blechlagen und Vorschläge zur Verbesserung des Wirkungsgrades bei der Spannungswandlung.
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    Excitation controller design of synchronous machine with output feedback using high and reduced-order models (1989)
    Springer
    Electrical engineering 72 (1989), S. 415-426 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Aus dem Modell einer Synchronmaschine in Form eines licaren zeitinvarianten Systems 8. Ordnung wird ein reduziertes Modell 4. Ordnung abgeleitet, das die wichtigsten Eigenwerte des Systems beibehält. Mit Hilfe eines algebraischen Verfahrens zur Bestimmung der Pole können lineare Regler der Erregung entworfen werden, die ein verbessertes Verhalten der Maschine bezüglich Stabilität und Spannungsregelung herbeiführen. Der für das Modell 4. Ordnung entworfene Regler zeigt bei Betrachtung am System 8. Ordnung keine Verschlechterung des Verhaltens. Auf die Bedeutung des Verfahrens für praktische Ausführungen bei großen Turbogeneratoren wird hingewiesen.
    Notes: Contents A practical 8th-order single-input multiple-output (SIMO) time-invariant linear model of a synchronous machine with first order conventional exciter, supplying power to the power system through a transformer and a transmission line has been developed. The criterion for the effective contribution of each system state to the total energy response at the output is used to obtain an adequate reduced 4th-order model in which the most important states and eigenvalues of the original model are retained. An efficient algebraic pole—placement method, using output feedback has been used to design the 8th and 4th-order models, physically realisable linear excitation controllers (with easily measurable state variables) for the purpose of substantially enhancing the dynamic stability characteristics and voltage control of a synchronous machine. The controller designed for the 4th-order model has also been tested on the 8th order model to demonstrate the validity of implementing reduced order formulations without degrading the performance of the control. A procedure for implementing the control strategies is presented in this study, and attention is drawn to the wider implications of implementing practical designs on large turbogenerators currently in use.
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    Analysis of temperature and stress fields in bars of induction motor cage during starting (1989)
    Springer
    Electrical engineering 72 (1989), S. 443-450 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Der Beitrag enthält eine Analyse des Temperatur-und Spannungsfeldes im Nutteil des Induktionsmotorstabs während eines Anlaufs. Bei den Berechnungen hat man die Parameteränderungen des Stabs berücksichtigt, die aus den Temperaturänderungen und den Wärmeabfluß vom Stab zu der Umgebung folgen. Zur Berechnung wurde die Methode der finiten Elemente verwendet.
    Notes: Contents The analysis of thermal field and stresses field in the slot part of the bar of an induction motor in the course of starting have been presented in the paper. The changes of the bar parameters resulting from the temperature changes and the heat flow from the bar into the surroundings have been considered. The finite element method has been used in the calculations.
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    Die Grenzen permanentmagneterregter Mehrphasenmaschinen mit Feldschwächung über die Ankerwicklung (1989)
    Springer
    Electrical engineering 72 (1989), S. 19-26 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents With regard to the converter expense many variable-speed drives operate using a field weakening.—In case of excitation provided by permanent magnets field weakening is realized by the armature winding: proper controlled currents generate ampere turns in direct axis change-able their magnitude and direction. — The effectiveness regarding to the attainable expense-reducing with high field weakening ratio and praxis orientated unit-capacity factor is rather small; dominating by this is the armature reaction.
    Notes: Übersicht Viele Stromrichterantriebe werden mit Rücksicht auf den Stromrichteraufwand mit Feldschwächung betrieben.—Dies erfolgt bei dauermagneterregten Maschinen über die Ankerwicklung. Ströme mit entsprechendem zeitlichen Verlauf erzeugen in einer mehrphasigen Wicklung längsmagnetisierende Ankerstrombelagsabschnitte, die nach Größe und Vorzeichen verändert werden.—Die Wirksamkeit bezogen auf die erreichbare Aufwandsreduzierung ist bei höheren Feldstellbereichen und praxisnaher Maschinenausnutzung erheblich eingeschränkt; dabei ist der Einfluß der Ankerrückwirkung dominierend.
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    Zur Inhomogenität des inneren Feldes und der Flußdichte von kornorientierten Elektroblechen aus Silizium-Eisen bei Fehlorientierungen in der Blechebene (1989)
    Springer
    Electrical engineering 72 (1989), S. 51-57 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents Starting from a model of a g.o. silicon-iron sheet with ideal goss-texture and an in-plane misoriented grain in the center the magnetization, the structure of the inner field and of the flux density in dependence on the external applied field are shown so that the deterioration of the flux guidance caused by such misoriented grains becomes visible.
    Notes: Übersicht Ausgehend von einem Modell eines kornorientierten Silizium-Eisenbleches mit idealer Goss-Textur und einem in der Blechebene fehlorientierten Korn im Zentrum werden die Magnetisierung, die Struktur des inneren Feldes und die Flußdichte berechnet. Die Struktur des inneren Feldes und der Flußdichte wird in Abhängigkeit vom aussteuernden Feld dargestellt, so daß die Verschlechterung der Flußführung durch derartig fehlorientierte Körner sichtbar wird.
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    Zur Berechnung von Schaltungen der Leistungselektronik im Spektralbereich (1989)
    Springer
    Electrical engineering 72 (1989), S. 125-132 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents In order to design power electronic circuits in the frequency domain an analysis method is presented which leads to standardized system equations and which is applicable in a general manner. This is obvious with power electronic circuits with a preset transfer function of the switching devices. This extended analysis method can be used to analyze and to compute all kinds of power electronic circuits. The numerical properties of the standardized system equations such as their regularity, convergence and truncation errors are also described. The results of the analysis method are shown for a line commutated converter as an example.
    Notes: Übersicht Für die Methode der Berechnung von Schaltungen der Leistungselektronik im Spektralbereich wird ein Verfahren angegeben, das zu standardisierten Systemgleichungen führt und allgemein angewendet werden kann. Das ist für Schaltungen mit vorgegebener Übersetzungsfunktion für die Ventilschaltung naheliegend. Es wird jedoch gezeigt, daß das Verfahren so erweitert werden kann, daß es sich auf alle Schaltungen der Leistungselektronik anwenden läßt. Die numerischen Eigenschaften der standardisierten Systemgleichungen, wie die Regularität, die Konvergenz und die Abbruchfehler werden auch angegeben. Die Anwendung des Verfahrens wird an einem einfachen Beispiel demonstriert.
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    Determination of the volume diffusion length of minority carriers within the base region of mono-crystalline solar cells by means of transient measurements (1989)
    Springer
    Electrical engineering 72 (1989), S. 157-164 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Zeitliches Abklingen der Leerlaufspannung (OCVD) an zahlreichen monokristallinen Silicium-Solarzellen nach IR-optischer und elektrischer Anregung (PIVD) wurde vermessen. Aus den Abkling-Flanken wurden die Lebensdauer und die Volumen-Diffusionslänge der Minoritätsladungsträger gewonnen, indem die Geometrie der Proben berücksichtigt wurde, vor allem dabei die Dicke der Basis. Des Verfahren benutzt Modellkurven, die durch Lösung der Differentialgleichung für die Diffusion der Minoritätsladungsträger bei kartesischer dreidimensionaler Geometrie der Proben erhalten wurden. Auswertungen anhand eines Ersatzschaltbildes, das in einer stärker dem Verhalten realer Solarzellen entsprechenden Weise den Abbau der gespeicherten Minoritätsträger beschreibt, ergeben neben der Minoritäten-Lebensdauer eine zweite Zeitkonstante, die in den Abkling-Flanken vorhanden ist und von der Anregung abhängt. Gute Übereinstimmung für die nach unterschiedlichen Verfahren ermittelten Werte der Diffusionslänge wurde nachgewiesen, und dies bestätigt die Brauchbarkeit dieser Methode.
    Notes: Contents Open-circuit voltage decay (OCVD) of many monocrystalline silicon solar cells after IR optical and electrical excitation (PIVD) has been measured. From the slopes of the decay the lifetime and volume diffusion length of minority carriers have been extracted, making allowance for the geometry of the devices, especially for the thickness of the base region. The procedure uses model curves which have been obtained by solving the differential equation for diffusion of minority carriers for a cartesian 3-dimensional geometry of the samples. More realistic circuit model evaluations of the stored charge of minority carriers yield a second time constant besides minority carrier lifetime, apparent in the voltage decay and excitation dependent. Good agreement has been achieved for differently extracted diffusion length, thus confirming the validity of this approach.
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    Expressions for solution of the Laplace and Helmholtz equations in three-dimensional eddy-current problems (1989)
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    Electrical engineering 72 (1989), S. 195-203 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Es werden allgemeine dreidimensionale Lösungen für die Laplacegleichung und die Helmholtzgleichung im Zylinderkoordinatensystem bei zeitlich harmonischen Vorgängen angegeben. Die vorgestellten Lösungsansätze, sowohl für die magnetischen- und elektrischen Feldgrößen, als auch für das übergeordnete Vektorpotential, erlauben eine analytische Lösung. Zusammenhänge zwischen Feldgrößen, Vektorpotential und übergeordnetem Vektorpotential werden diskutiert. Einige technische Anwendungsbeispiele für die analytische Berechnungsmethode werden angegeben.
    Notes: Contents General three-dimensional solutions are given for the Laplace equation and Helmholtz equation in the cylindrical co-ordinate system, for processes which remain harmonic with time. The expressions for solution which are presented, not only for the magnetic and electrical field variables, but also for the higher-order vector potential, permit an analytical solution. The interrelationships between the field variables, the vector potential, and the higher-order vector potential are discussed. Several examples of engineering applications of the analytical calculation method are given.
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    Die Induktivität von Induktionsrinnenöfen und anderer koaxialer Wicklungsanordnungen mit zylindrischem Eisenkern (1989)
    Springer
    Electrical engineering 72 (1989), S. 225-232 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents Calculation, for the rotation-symmetrical case, of the magnetic field and the magnetic energy of two coaxial, multilayer cylindrical coils which are arranged concentrically around a cylindrical iron core, and are carring a direct current. For the special case, where the secondary winding consists of one turn, arranged axial-symmetrically to the induction winding, leakage inductivity follows from the magnetic energy.
    Notes: Übersicht Für den rotationssymmetrischen Fall werden das Magnetfeld und die magnetische Energie zweier koaxialer, mehrlagiger Zylinderspulen, welche konzentrisch um einen zylindrischen Eisenkern angeordnet und von Gleichstrom durchflossen sind, berechnet. Für den Sonderfall, daß die sekundäre Wicklung aus einer Windung besteht und axialsymmetrisch zur Induktorspule angeordnet ist, folgt aus der magnetischen Energie die Streuinduktivität von Induktionsrinnenöfen.
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    Algorithmic methods of induction machines parameters estimation from measured slip-curves (1989)
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    Electrical engineering 72 (1989), S. 239-249 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Der Beitrag stellt Methoden zur Bestimmung der Parameter von mathematischen Modellen der Induktionsmaschinen dar. Es wird auf eine objektive algorithmische Weise die Schrittregressionmethode angewendet. Die experimentelle Grundlage der Parameterschätzung sind gemessene Schlupfkennlinien. Zuerst wird die einfache Schätzmethode beschrieben, die nur eine ausgewählte Charakteristik als Grundlage zur Parameterbestimmung ausnutzt. Danach werden die mehrdimensionalen Schätzverfahren dargestellt, die zur Parameterbestimmung gleichzeitig eine Zahl von Schlupfkennlinien ausnutzen. Als Ergebnis bekommt man einen universellen Parametersatz. Die vorgestellten Methoden sind allgemein, aber die Beziehungen im Beitrag betreffen nur Doppelkäfigmaschinen. Am Schluß des Beitrags werden die Anwendungsbeispiele für die Doppelkäfigmaschine und den Stromverdrängungsmotor angegeben. Die erhaltenen Parameter werden für Berechnungen der typischen dynamischen Vorgänge benutzt. Die rechnerischen Ergebnisse werden mit auf experimentellem Weg ermittelten Verläufen verglichen.
    Notes: Contents The paper presents methods of determining the parameters of induction machine models in objective, algorithmic way employing the stepwise-regression method. The experimental base for parameter-estimation are measured slip-curves of the machine. At first a singular estimation method is presented, which uses one slip-curve as the source for determining the parameters. Then multidimensional estimation methods are introduced, which take several slip-curves into account and result in one versatile set of parameters. The methods are quite general, but in this paper specific formulae are given for double-cage machines. The paper is concluded with examples of application to double-cage and deep-bar motors, and the obtained parameters are used in computations of typical transients which are compared with recorded curves.
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    An analytic method to study open thick microstrips (1989)
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    Electrical engineering 72 (1989), S. 283-291 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht In dieser Studie wird ein analytisches Verfahren zur Untersuchung der Dispersionskennlinien von Mikrostreifen endlicher Breite dargelegt. Mit Hilfe des hertzschen Vektorpotentials wurde die Integralgleichung zur Bestimmung der Stromverteilung und der Ausbreitungskonstante aufgestellt. Die numerische Auswertung ergab, daß die durch die endliche Leitfähigkeit der Leiter bedingte Dämpfungskonstante kleiner bei halbkreisförmigen als bei rechteckigen Mikrostreifen ist. Im Fall der Stromverteilung war die Longitudinalkomponente zumindest das Zehnfache der Transversalkomponente; daher genügt es, zur Untersuchung von Mikrostreifen endlicher Breite, nur die Longitudinalkomponente des Stroms heranzuziehen.
    Notes: Contents In this paper an analytic method of study the dispersion characteristics of an open thick microstrip is presented. By the help of the hertzian vector it was found the integral equation for the current distribution and the transmission coefficient. From the numerical results it is shown that the attenuation constant due to the conductor loss is less in the rounded edge microstrip than in the rectangular one. For the current distribution the transverse current was at least ten times less the longitudinal one. So to study an open thick microstrip we have good approximation by using only the longitudinal current.
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    A digital method for sinewave generation (1989)
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    Electrical engineering 72 (1989), S. 327-331 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Es wird ein einfaches Verfahren zur Erzeugung von Sinuswellen mit konstanter Amplitude über ein relativ breites Frequenzband beschrieben. Das Verfahren beruht auf der Erzeugung einer Anzahl von Stichproben innerhalb einer Sinuswellenperiode, indem ein Aufwärts-/Abwärts-Zähler und ein Dekodierer herangezogen werden, um daraufhin diese Stichproben in einem Addierer und einem Verstärker mit geregelter Verstärkung zu verarbeiten und da-durch eine stufenartige Näherung der Sinuswelle zu erreichen. Die Gesamtverformung der Oberschwingungen (THD) der entstandenen Sinuswelle kann durch ein Tiefpaß-Filter herabgesetzt werden.
    Notes: Contents A simple method to digitally produce a sine wave-form with constant amplitude over a relatively wide band of frequencies is described. The method is based on the generation of a number of samples per cycle of the sine wave-form, using an up/down counter and a decoder, and then processing these samples in a summing amplifier and in a controlled-gain amplifier to produce a staircase approximation of the sinewave. The total harmonic distortion of the resulting waveform can be reduced substantially by inserting a low-pass filter.
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    On the identification of redundant constraints in optimisation problems (1989)
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    Electrical engineering 72 (1989), S. 341-347 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Auf der Basis der “Extended Sign Test Methods” wird ein Verfahren entwickelt, das zur Identifizierung der redundanten Nebenbedingungen bei Optimierungsproblemen geeignet ist. Hierzu wird eine Reihe von linearen Programmie-rungsproblemen gelöst, wobei jedes auf die minimale Abweichung einer Nebenbedingung vom Grenzvieleck der zulässigen Lösungen führt. Mit Hilfe einiger Theoreme ist es dann möglich, aus den dazwischenliegenden Simplextableaus die redundanten und die nichtredundanten Nebenbedingungen zu erkennen. Als Beispiel wird der optimale Lastfluß eines einfachen Testnetzes untersucht.
    Notes: Contents A procedure, based on the “Extended Sign Test Method”, is given to classify the constraints of an optimisation problem as either redundant or nonredundant. A series of LP problems is solved; for each problem the slack of a particular constraint is minimised with respect to the feasible region. With the aid of several theorems the intermediate tableaux are scanned for the identification of redundant and nonredundant constraints. The algorithm is demonstrated by applying it to the optimal power flow of a simple testsystem.
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    Beugung elektromagnetischer Wellen am ideal leitenden zylindrischen Hohlspiegel (1989)
    Springer
    Electrical engineering 72 (1989), S. 363-368 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents The “problem of relative convergence” [1–3] can be observed analytically while treating the diffraction by a cylindrical concave mirror. In order to solve this boundary value problem, we describe the tangential fields on the mirror using orthogonal expansions, which lead to the well-known results for a closed cylinder. Numerical data are presented like current- and far field distributions; especially the behaviour of the current at the edge is treated in detail.
    Notes: Übersicht Die Behandlung der Beungung am zylindrischen Hohlspiegel (vgl. auch Sommerfeld [4]) bietet die Möglichkeit, das generell bei Zwei- oder Mehrraumproblemen auftretende “Problem der relativen Konvergenz” [1–3] analytisch zu untersuchen. Zur Lösung dieses Randwertproblems werden für die tangentialen Feldgrößen auf dem Spiegel Orthogonalansätze gemacht, die für den Fall des Vollzylinders auf die klassische Lösung führen. Die numerische Auswertung umfaßt Strom- und Fernfeldverläufe; insbesondere wird das Verhalten der Flächenstromdichte an der Kante untersucht.
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    Theoretical and experimental analysis of the steady state operation and the losses in a spuirrel cage induction motor (1989)
    Springer
    Electrical engineering 72 (1989), S. 369-376 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Es wird eine vom Konzept her einfache, aber allgemeingültige Theorie vorgestellt, die das Verhalten eines in Stern geschalteten Käfigläufermotors im stationären Betrieb erklärt. Möglichkeiten zur Berücksichtigung der Nutöffnungen und der Sättigung werden diskutiert. Die Analyse ergibt einen Einblick in den Zusammenhang zwischen den Oberfeldern, die durch die Wicklungsverteilung und die Sättigung hervorgerufen werden, und den Verlusten. Zusammen mit einem Lösungsalgorithmus wird ein Ausdruck für das Moment abgeleitet. Die theoretischen Ergebnisse werden experimentell überprüft.
    Notes: Contents A conceptually simple, but general theory is proposed to explain the behaviour of aY-connected squirrel cage induction machine operating in steady state. Means for accounting for slot openings and saturation are discussed. The analysis provides an insight into how harmonics due to both magnetomotive force distribution and saturation contribute to losses. An expression for torque is derived, together with an algorithm for solution. Finally, results obtained are compared with those found on an actual machine.
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    URL: http://dx.doi.org/10.1007/BF01573754
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    Determination of excitation parameter limits for generator dynamic stability (1989)
    Springer
    Electrical engineering 72 (1989), S. 357-362 
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    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Erregersystem und Spannungsregler beeinflussen bekanntlich die Stabilität von Synchrongeneratoren beträchtlich. In dem Beitrag werden Parameter des Erregersystems, insbesondere die Verstärkung und die dominante Zeitkonstante an der Stabilitätsgrenze berechnet. Nach einem Erregermodell erster Ordnung wird ein solches vierter Ordnung behandelt. Die Darstellung mittels Stabilitätskarten kann als Hilfsmittel bei der Parameterwahl genutzt werden.
    Notes: Contents The voltage regulator and the excitation system are known to affect strongly the dynamic stability of a synchronous generator. This effect is often detrimental, sometimes leading even to dynamic instability. This paper concentrates on determining the excitation system parameter values for which the generator's dynamic stability becomes marginal. This defines a stable and an unstable region in the space of the dominant excitation system parameters, namely the transient or the steady state gain and the dominant time constant of the excitor-voltage regulator system. In the case of a first order excitation system model, the stability limits can be determined analytically in the form of an inequality constraint. A fourth order excitation system is also examined but this time the stability limits are computed using the concept of the gain margin. The determination of the stable region in the parameter space is an extremely useful tool for the proper selection of excitation system parameter settings.
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    URL: http://dx.doi.org/10.1007/BF01573717
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    Application of back-action evading amplifier to optical network communications (1989)
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    Optical and quantum electronics 21 (1989), S. 131-136 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract This paper shows applications of the back-action evading amplifier, which amplifies a signal without degradation of the signal-to-noise ratio (SNR), to optical decoupling systems and clarifies the effects of the number of branches and the amplitude gain to SNR. As a result, it is shown that this concept provides an ideal optical system for networks with optical branches.
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    URL: http://dx.doi.org/10.1007/BF02190078
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    Optical beam deflection using dynamic volume reflection gratings (1989)
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    Optical and quantum electronics 21 (1989), S. 151-154 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We propose a scheme for optical beam deflection using dynamic volume reflection gratings. Since the direction change of the diffracted beam with the recording wavelength is much larger for a reflection grating a passive beam-tilting element may not be required.
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    URL: http://dx.doi.org/10.1007/BF02190081
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    Double-beam two-photon optical bistability in a Fabry-Perot cavity with polar molecules (1989)
    Springer
    Optical and quantum electronics 21 (1989), S. 415-422 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Optical bistability in a micrometre-sized Fabry-Perot cavity, filled with appropriate polar molecules, is analysed after two incident beams (with frequenciesgw 1 andgw 2) produce in the system a two-photon resonance at frequencygw 1 +gw 2. One-photon resonances at the frequenciesgw 1 andgw 2 are discarded. It was not necessary to assume a particular relationship betweengw 1 andgw 2, and the single-beam two-photon optical bistability whengw 1 andgw 2 are of the same order or equal is emphasized.
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    Cutoff behaviour of graded-index slab waveguides (1989)
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    Optical and quantum electronics 21 (1989), S. 451-462 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The cutoff behaviour of graded-index planar waveguides is analysed in terms of the normalized waveguide parameters by using the multilayer technique and the WKB approach. The results show a very high degree of accuracy when checked against exact known values for exponential and hyperbolic index profiles. A set of universal plots showing the general features is given for the cutoff values of both fundamental and first-order modes. The TM polarization is also studied by comparison with the TE one.
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    Semiconductor laser optical amplifiers in switching and distribution networks (1989)
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    Optical and quantum electronics 21 (1989), S. S59 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Applications of semiconductor laser optical amplifiers in coherent multichannel systems are investigated with respect to the switching and distribution of many channels to a large number of customers. All-optical switching of data signals is achieved with the optical amplifier operating as a frequency converter. Measurements of the conversion efficiency and a transmission experiment with a 1500 GHz conversion range are described. Possible applications are all-optical ‘multipoint to point’ and ‘point to multipoint’ switching. Optical amplifiers may also be useful in multichannel distribution networks to compensate for combining and splitting losses. We discuss an example demonstrating how optical amplifiers increase the number of customers in a coherent multichannel distribution system.
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    A model for noise processes in semiconductor laser amplifiers, part 1: the travelling-wave semiconductor laser amplifier (1989)
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    Optical and quantum electronics 21 (1989), S. S33 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A new model for the noise processes in a travelling-wave semiconductor laser amplifier is presented. This model is based on applying perturbation techniques to the basic travelling-wave rate equations to deduce the noise rate equations. These equations are then used to calculate the power spectral densities of the intensity, electron density and phase noises introduced into a single signal mode propagating through the amplifier. The model can be applied to any gain profile within the amplifier, ranging from unsaturated to completely saturated. Furthermore, in contrast to most other semiconductor laser amplifier models, this model does not require the homogenization of the photon field over the length of the device.
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    Fibre Brillouin amplifiers (1989)
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    Optical and quantum electronics 21 (1989), S. S105 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The operation and noise properties of fibre Brillouin amplifiers are described, and the applications demonstrated to date are reviewed.
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    Design of FIR filters with reduced computations (1989)
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    Circuits, systems and signal processing 8 (1989), S. 17-23 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The performance of a symmetric nonrecursive filter can be improved by multiple use of the same filter. The method is based on an Amplitude Change Function (ACF). An approach to the design of nonrecursive filters using an ACF is discussed in this paper. The prototype filter chosen is a Recursive Running Sum (RRS) filter which does not require any multipliers for its implementation. The required filter specifications are met by multiple use of the RRS filters. The overall filter requires a much smaller number of multiplications and adders than the one designed using the conventional method. It is shown that this method provides reduced noise due to coefficient quantization and product quantization compared with the conventional design technique.
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    Statistical analysis of two nonlinear least-squares estimators of sine-wave parameters in the colored-noise case (1989)
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    Circuits, systems and signal processing 8 (1989), S. 3-15 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract This paper establishes the large-sample accuracy properties of two nonlinear least-squares estimators (NLSE) of sine-wave parameters: the basic NLSE, which ignores the possible correlation of the noise, and the optimal NLSE, which, besides the sine-wave parameters, also estimates the noise correlation (appropriately parametrized). It is shown that these two NLS estimators have thesame accuracy in large samples. This result provides complete justification for preferring the computationally less expensive basic NLSE over the “optimal” NLSE. Both estimators are shown to achieve the Cramér-Rao Bound (CRB) as the sample size increases. A simple explicit expression for the CRB matrix is provided, which should be useful in studying the performance of sine-wave parameter estimators designed to work in the colored-noise case.
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    URL: http://dx.doi.org/10.1007/BF01598742
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    Synthesis of two-dimensional losslessm-Ports with prescribed scattering matrix (1989)
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    Circuits, systems and signal processing 8 (1989), S. 97-119 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Multidimensional lossless networks are of special interest for use as reference structures for multidimensional wave digital filters [l]–[3]. The starting point of the presented synthesis procedure for two-dimensional representatives of the networks mentioned is a scattering matrix description of the desired multiport. This given matrix is assumed to have those properties which have turned out to be necessary [9], [10] for any scattering matrix of a multidimensional lossless network. The method presented for the synthesis of 2-D reactancem-ports is based mainly on known properties of block-companion matrices and the factorization of a univariable rational matrix which is discrete para-Hermitian and nonnegative definite on the unit circle. The resulting network always contains only a minimal number of frequency-dependent building elements. No restrictions are made concerning the coefficients of the rational entries of the scattering matrix; they may be either real or complex, so as to include even complex networks which are of special interest for multi-dimensional wave digital filters [3].
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    Systems which possessg- andh- Representations (1989)
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    Circuits, systems and signal processing 8 (1989), S. 145-162 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Examples are given concerning the range of applicability of recent representation results that provide a means of studying the input-output properties of nonlinear systems in terms of the familiar impulse-response concept, and which extend the concept of integral transformation to nonlinear maps. We show that such representations, which we call “g-” and “h-representations,” exist for important classes of systems governed by nonlinear integral equations. In particular, it is proved that a large class of maps that have Volterra series representations also have these representations.
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    Photonic switches and switch arrays on LiNbO3 (1989)
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    Optical and quantum electronics 21 (1989), S. 1-15 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract In recent years there has been tremendous progress in lithium niobate-based photonic switches. The various switch configurations proposed and implemented, and their characteristics, are reviewed. A summary of the device technology is given. Performance analysis based on different architecture and the size of arrays that can be relalized are discussed.
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    Theory of two-section laser amplifiers (1989)
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    Optical and quantum electronics 21 (1989), S. S15 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A new theory of two-section amplifiers has been developed in order to account explicitly for dispersive effects arising from the carrier dependence of the refractive index. It has been found that non-linear and bistable effects in two-section devices, which are conventionally attributed to saturable absorption, contain a stong component of dispersive non-linearity. The implication is that the advantages claimed for two-section amplifiers over single-section devices may not be as great as had hitherto been thought.
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    Performance of a dual-stage semiconductor laser amplifier for optical transmission repeater system (1989)
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    Optical and quantum electronics 21 (1989), S. S75 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The performance of a dual-stage semiconductor laser amplifier consisting of a preamplifier and a power amplifier is evaluated theoretically and experimentally. The dual-stage optical amplifier can offer high-gain amplification with low noise figure by using a low-noise amplifier as a preamplifier. Using the dual-stage amplifier, 2.4 Gbits−1 193 km optical fibre transmission was demonstrated. In addition, by applying an automatic power control system to the dual-stage amplifier, output power stabilization with wide dynamic range was obtained.
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    Announcement (1989)
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    Optical and quantum electronics 21 (1989), S. 16-16 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
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    Ray transfer matrix analysis of multiple-prism dye laser oscillators (1989)
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    Optical and quantum electronics 21 (1989), S. 47-54 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A ray transfer matrix description of multiple-prism beam expanders used to produce narrow-linewidth emission in pulsed dye lasers is given. The formulae are then applied to describe beam divergence characteristics of a narrow-linewidth multiple-prism grating oscillator. A comparison between theory and measured beam divergence and laser linewidth is provided.
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    Pulse shortening of 5×103 by the combined pulse forming of dye oscillators, saturated amplifiers and gated saturable absorbers (1989)
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    Optical and quantum electronics 21 (1989), S. 55-61 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A simple excimer-laser-pumped cascade dye laser-amplifier system has been presented which due to the combined pulse-forming effects of cascade dye lasers, saturated amplifiers and gated saturable absorbers, is capable of generating single 3 ps pulses.
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    3.5 μm optical communication experiment at 100 Mbits−1 using a PbCdS diode laser (1989)
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    Optical and quantum electronics 21 (1989), S. 69-72 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A mid-infrared optical communication experiment using a lead-salt diode laser emitting at 3.5 μm is reported. Bit-error rate measurements have been performed for pulse code modulated data at 100 Mbits−1 using a fluoride glass fibre as a transmission channel. A bit-error rate better than 10−10 was achieved at a signal-to-noise ratio of 20 dB.
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    Relationship between field shift and phase constant change in two-dimensional three-layered dielectric or hollow waveguides due to uniform bends (1989)
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    Optical and quantum electronics 21 (1989), S. 63-67 
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    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract It is shown theoretically that the field shift Δx and phase constant change Δβ in two-dimensional three-layered dielectric or hollow waveguides bent uniformly with large bending radiusR are related by Δx = 2RΔβ/β 0, whereβ 0 is the axial phase constant. The relationship predicts that the field distributions of the TE0 or TM0 mode shift toward the outward direction of bending, whereas those of other TE n or TM n (n=1,2,...) modes shift inward in a hollow waveguide. Characteristic features in dielectric waveguides are also described.
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    Theoretical analysis of a PSK coherent heterodyne optical receiver using external cavity semiconductor lasers (1989)
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    Optical and quantum electronics 21 (1989), S. 87-92 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The performance of a PSK heterodyne optical transmission system using external cavity semiconductor lasers as remote and local oscillators in evaluated theoretically. The actual shape of the instantaneous frequency fluctuations power spectral density of the optical oscillators is taken into account, obtaining indications for optimum design of the external optical feedback.
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    Analysis of non-linear multilayer waveguides with Kerr-like permittivities (1989)
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    Optical and quantum electronics 21 (1989), S. 109-116 
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    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract This paper presents a semi-analytical method for calculating the dispersion relationships for stationary non-linear TE waves guided by general multilayer waveguides with Kerr-like permittivities. The non-linear wave equations are solved rigorously for each layer, and the mode index and field distribution are systematically determined so as to satisfy the boundary conditions at all interfaces. To verify the validity of the present method, a non-linear graded-index waveguide is approximated by a number of step layers and the resultant multilayer waveguide is analysed numerically. The convergence properties of mode index and total power flow are presented, and these are compared with direct solutions of the non-linear wave equation by the numerical integration method. The dispersion relationships for a non-linear multiple-quantum-well waveguide have also been investigated under two simple permittivity models. The present method is useful for the analysis of non-linear graded-index waveguides in addition to non-linear multilayer waveguides such as the multiple-quantum-well structure.
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    A megawatt excimer laser of small discharge volume (3.8 cm3) (1989)
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    Optical and quantum electronics 21 (1989), S. 147-150 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We demonstrated intense laser action form a 14 cm gain length, 3.8 cm3 active volume XeCl laser. The laser peak power of 1.3 MW was comparable with the best results obtained from a similar small active volume excimer laser, and the laser energy of 40 mJ per pulse obtained from our device was considerably higher.
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    Thermally induced optical bistability in PbTe at room temperature (1989)
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    Optical and quantum electronics 21 (1989), S. 159-165 
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    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Thermally induced optical bistability by continuous-wave CO2 laser excitation is obtained for the first time in PbTe. Optical switching of the etalon atT=300K is achieved for input powers of tens of milliwatts. A theoretical analysis of the input-output characteristics is presented, where the temperature dependence of the free carrier absorption has been accounted for.
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    Pixellation of optically bistable elements (1989)
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    Optical and quantum electronics 21 (1989), S. 191-203 
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    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The elements of optical logic arrays can, in principle, be shielded from inter-element crosstalk by material pixellation. This confinement might seem to allow closer packing of such elements. However, using a Fourier optics approach to diffusion, we show that the pixellation process itself prevents radial removal of heat, and this can seriously affect device operation. The importance of this effect is illustrated by means of a numerical simulation.
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    A new c.w. CO laser: simultaneous double-wavelength operation of tunable CO laser (1989)
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    Optical and quantum electronics 21 (1989), S. 233-234 
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    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We demonstrate simultaneous two wavelength operations of a cooled CO laser. Tunable operations over seven vibrational bands is achieved.
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    Excitation of theE u polariton in a centrosymmetric crystal by four-wave mixing (1989)
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    Optical and quantum electronics 21 (1989), S. 235-240 
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    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We investigate the contribution ofE u phonon-polariton to the four-wave mixing signal obtained in a TiO2 crystal. Experimental results indicate that the contribution is via second- oder quadrupolar susceptibility χ yxxy .
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    Two-photon absorption and emission dynamics of bulk GaAs (1989)
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    Optical and quantum electronics 21 (1989), S. 283-306 
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    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Bulk n-type GaAs (dopant silicon) is investigated with picosecond pump pulses of a passively mode-locked Nd:glass laser. The two-photon absorption, the spontaneous emission, and the longitudinal amplified spontaneous emission are measured. The experimental results are compared with computer simulations and relevant material parameters are determined.
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    Float-glass: An industrial substrate for integrated optics (1989)
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    Optical and quantum electronics 21 (1989), S. 307-319 
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    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Low-loss single-mode waveguides form at the surface of glass in contact with liquid tin during the float process. Theoretical and experimental studies have demonstrated that float-glass can serve as an industrial substrate for integrated optics.
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    Approximate solution of optical soliton in lossless fibres with third-order dispersion (1989)
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    Optical and quantum electronics 21 (1989), S. 335-341 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A near zero-dispersion regime, fundamental soliton with third-order dispersion is considered. There are three different waves radiated from the soliton. We find a threshold condition for the radiated waves. Below the threshold condition a stable soliton exists; an approximate soliton solution is obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02027304
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    A parametric study of surface-discharge nitrogen lasers (1989)
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    Optical and quantum electronics 21 (1989), S. 353-362 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A parametric study of sandwich-type discharge chamber nitrogen lasers has been carried out. A non-monotonic dependence of the energy emitted by the laser and the discharge chamber thicknessτ is found. Discharge chambers withτ = 1 have the best electro-optical efficiency. The ratio between the electrode gap,d, andτ is found to be a scaling parameter. The possible influence of wall ablation in the comportment is also discussed.
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    URL: http://dx.doi.org/10.1007/BF02028179
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    Saturation effects at backward-stimulated scattering in the single-mode regime of interaction (1989)
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    Optical and quantum electronics 21 (1989), S. 381-395 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The effects of amplitude modulation of interacting waves at stimulated Mandelstam-Brillouin scattering (SMBS) in a monomode fibre caused by the noise origin of the initial Stokes wave are investigated both theoretically and experimentally. Depending on the determined conditions, there can taken place either a smoothing of the noise amplitude modulation or its preservation in the Stokes radiation in the deep saturation regime of SMBS. Amplitude modulation with period corresponding to the double time of radiation propagation through the fibre is observed along with noise-amplitude modulation of the Stokes and pump waves. The effect of this period prolongation is discussed. The influence of phase fluctuations on amplitude modulation of interacting waves is investigated. The role of phase correlations in the feedback regime of SMBS is considered. Experimental results are in good agreement with numerical calculations.
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    URL: http://dx.doi.org/10.1007/BF02028181
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    Parametric solitons on Raman resonance and self-induced transparency in silica optical fibre (1989)
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    Optical and quantum electronics 21 (1989), S. 429-433 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract An analytical and numerical analysis of the dynamics of parametric solitons on Raman resonance is performed. The results of calculations describe an effect of self-induced transparency for parameteric solitons and the influence of the initial phase on Raman Stokes gain and anti-Stokes absorption. This can be used to maintain the process of energy transfer between pulses.
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    URL: http://dx.doi.org/10.1007/BF02028186
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    A laser amplifier model for system optimization (1989)
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    Optical and quantum electronics 21 (1989), S. 463-470 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A laser amplifier system model has been developed, incorporating many of the features of real devices. The theoretical performance of systems with several amplifiers is investigated to illustrate the effects of optical filters and control techniques. Realistic and practical system limits are also identified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02189126
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    Acoustic-optic frequency shifter using coaxial fibres (1989)
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    Optical and quantum electronics 21 (1989), S. 491-498 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract In this paper a frequency shifter using coaxial fibres with the applied acoustic wave is proposed. Two frequency shifts for a given coaxial structure are found to be possible when the coaxial fibre is excited with appropriate light patterns and acoustic model power. The general design procedure for such a frequency shifter is also outlined.
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    URL: http://dx.doi.org/10.1007/BF02189129
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    Succession of one-soliton pulses in the zero-dispersion region of silica optical fibres: The role of the phase difference between the adjacent pulses (1989)
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    Optical and quantum electronics 21 (1989), S. 507-510 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Some features of the propagation of one-soliton successions in the third order dispersion region are presented for the case where the phase difference between adjacent pulses is π rads. We show that this considerably improves the stability of the pulses in the zero-dispersion region. Walk-off can be diminished by increasing the number of pulses in the succession. These features may help optimize the bandwidth of non-linear fibre communication links.
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    URL: http://dx.doi.org/10.1007/BF02189131
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    Book reviews (1989)
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    Optical and quantum electronics 21 (1989), S. 525-529 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
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    URL: http://dx.doi.org/10.1007/BF02189135
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    On approximate theories of single-mode rectangular waveguides (1989)
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    Optical and quantum electronics 21 (1989), S. 517-520 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We present a new scheme of computation for the CEVAR (cosine-exponential field based variational method) for modelling wave propagation in single mode rectangular waveguides. The method avoids non-linear optimization. We show that the fully optimized weighted index approach is identical to the CEVAR method in which the Rayleigh quotient is optimized to obtain the best separable approximation to the field propagating in single mode guides with rectangular dimensions.
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    URL: http://dx.doi.org/10.1007/BF02189133
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    Special issue on: Charge transport assisted optical nonlinearities (1989)
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    Optical and quantum electronics 21 (1989), S. 533-533 
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    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
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    URL: http://dx.doi.org/10.1007/BF02189136
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    The pseudorandom sequence of arrays (1989)
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    Circuits, systems and signal processing 8 (1989), S. 133-144 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Pseudorandom (or maximal length) sequences and arrays have been known for a long time, and have been reported by several authors. Pseudorandom volumes have also been mentioned. This paper presents a different type of sequence of arrays in which the arrays share many properties with the pseudorandom arrays of the literature, and the sequence (or group) of arrays has many properties in common with the pseudorandom sequences. It is proposed that this set of arrays be called a “pseudorandom sequence of arrays,” or PRSAs. Some interesting properties of the PRSA as well as its practical (hardware) implementation have been mentioned. It has also been shown that our result is a special case of the generalN(3)/D(3) case.
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    URL: http://dx.doi.org/10.1007/BF01599934
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    A recursive parameter estimator yielding exponential convergence under sufficient excitation (1989)
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    Circuits, systems and signal processing 8 (1989), S. 207-228 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract For linear time-invariant discrete-time systems, an exponentially convergent recursive parameter identification scheme is derived requiring only that the regression vector be sufficiently exciting, that is the sum of the outer products of the regression vector is eventually positive definite. The algorithm produces a parameter estimate that converges to the batch-form (nonrecursive) least-squares estimate without requiring a persistent excitation. The rate of convergence can be selected as a design parameter. If the regression vector is persistently exciting, it is shown that a forgetting factor can be added to the formulation in such a way that the magnitude of the forgetting factor and the rate of exponential convergence can be set separately.
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    URL: http://dx.doi.org/10.1007/BF01599938
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    Image modeling and restoration: A new approach (1989)
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    Circuits, systems and signal processing 8 (1989), S. 229-229 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01599939
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    Some circuits and systems applications of semistate theory (1989)
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    Circuits, systems and signal processing 8 (1989), S. 235-260 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The semistate theory of circuits and systems is reviewed with regard to its applications. Among these latter discussed are electronic circuit design and analysis, hysteresis, knot generation, neural networks, and constrained robot characterizations.
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    URL: http://dx.doi.org/10.1007/BF01598413
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    On Hautus-type conditions for controllability of implicit linear discrete-time systems (1989)
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    Circuits, systems and signal processing 8 (1989), S. 289-298 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Four notions of controllability for general (i.e., possibly nonregular) implicit linear discrete-time systems are considered. Relationships between them are studied. A Hautus-type characterization of all of these notions is also given.
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    URL: http://dx.doi.org/10.1007/BF01598416
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    Strategies for finite-time control in singular systems in open- and closed-loop configurations (1989)
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    Circuits, systems and signal processing 8 (1989), S. 299-312 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract A new concept of system equivalence which allows the establishment of a formal relation between singular and regular systems has been introduced. By applying this concept, an open-loop strategy for finite-time control of a given solvable singular system, which is simple for both computation and implementation, is developed. A strategy for finite-time output feedback control is considered for a continuous singular system. It is shown that provided the system is observable, a desired polynomial command for finite-time control can be determined from a finite sequence of output measurements sampled at discrete instants of time.
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    URL: http://dx.doi.org/10.1007/BF01598417
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    Reachability, observability, and minimality for shift-invariant two-point boundary-value descriptor systems (1989)
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    Circuits, systems and signal processing 8 (1989), S. 313-340 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In this paper we study the system-theoretic properties of two related classes of shift-invariant two-point boundary-value descriptor systems (TPBVDSs), namelydisplacement systems for which Green's function is shift-invariant, andstationary systems for which the input-output map is stationary. For such systems it is possible to obtain detailed characterizations of the properties of weak reachability and observability introduced in [16] and of minimality as well. An important difference, that has also been noted before in a different context [9], is that there is a certain level of nonuniqueness in minimal realizations. Another property that is studied in this paper is that of extendibility, i.e., the concept of considering a TPBVDS as being defined on a sequence of intervals of increasing length. Necessary and sufficient conditions for extendibility are given.
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    URL: http://dx.doi.org/10.1007/BF01598418
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    Call for papers (1989)
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    Circuits, systems and signal processing 8 (1989), S. I 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01598422
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    Signal scaling in cascade digital filters (1989)
    Springer
    Circuits, systems and signal processing 8 (1989), S. 421-426 
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    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Scaling of filter variables is central to fixed-point implementation of digital filters. A simple method of scaling based on scaling constants of individual sections of a cascade digital filter is presented. The proposed method saves much computational labor in the implementation of higher-order digital filters. Maximal amplitude expressions of second-order filter transfer functions are also presented.
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    URL: http://dx.doi.org/10.1007/BF01599763
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