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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Electrical engineering 79 (1996), S. 393-406 
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Wir behandeln magnetissche FelderB z (r, t) undB φ (r, t), die in homogene leitfähige Kreiszylinder mit dem Radiusr 0 diffundieren mit der Randbedingung, daß fürr=r 0 die Felder proportionalt n sind. Dabei wird die Laplace-Transformation benutzt, wobei deren Inversion für größere Werten sehr umständlich ist. Durch die Einführung bestimmter Polynome kann das Vorgehen sehr erleichtert werden. Diese Polynome haben bemerkenswerte Eigenschaften und können für viele Anwendungen sehr nützlich sein. Will man z.B. die dissipierten Energien berechnen, so benötigt man dazu gewisse unendliche Summen der Eigenwerte der Probleme, die mit Hilfe der genannten Polynome leicht berechnet werden können. Die Behandlung der analogen ebenen Probleme zeigt, daß diese Polynome das zylindrische Analogon der Bernoulli-und Euler-Polynome sind. Die Beziehungen zwischen unseren Polynomen und Fourier-Bessel-Reihen sind dieselben wie die zwischen Bernoulli-und Euler-Polynomen und Fourier-Reihen. Abschließend werden auch Hohlzylinder behandelt. Die Ergebnisse sind ähnlich, jedoch erheblich komplizierter als für Vollzylinder.
    Notes: Contents We discuss magnetic fieldsB z (r, t) andB φ (r, t) diffusing into homogeneous conducting circular cylinders of radiusr 0 with boundary conditionsB z (r 0,t) orB φ (r 0,t) proportional tot n. Laplace-transforms are used. The main difficulty is their inversion for larger values ofn. The procedures can be strongly simplified by the introduction of certain polynomials. They have very remarkable properties. They are also helpful for many applications. If one wants to calculate the dissipated Joule-heat for instance, one needs certain infinite sums related to the eigenvalues of the problems. These infinite sums can easily be evaluated with the help of the polynomials mentioned. The corresponding plane problems are also considered in order to show that these polynomials are the cylindrical analogues of Bernoulli- and Euler-polynomials. The relations between our polynomials and Fourier-Bessel-expansions are the same as those between Bernoulli- and Euler-polynomials and Fourier-expansions. Finally hollow cylinders are discussed, too. The results are similar but more complicated than for full cylinders.
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Electrical engineering 78 (1995), S. 345-363 
    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 werden die Green'schen Funktionen transienter ebener Wellen in endlichen und unendlichen verlustbehafteten Medien behandelt. Im Fall endlicher Medien können diese durch zwei wesentlich verschiedene unendliche Reihen dargestellt werden, deren eine für kleine, Zeiten, deren andere für große Zeiten extrem rasch konvergiert. In der Grenze unendlicher Lichtgeschwindigkeit ergeben sich diffundierende elektromagnetische Felder, die in einer vorhergehenden Arbeit behandelt wurden [1]. In diesem Spezialfall sind die Felder durch θ-Funktionen gegeben, deren unterschiedliche Reihendarstellungen über die Jacobi-Transformationen miteinander zusammenhängen. Die Ergebnisse der vorliegenden Arbeit verallgemeinern diese Zusammenhänge.
    Notes: Contents This paper treats the Green's functions of transient plane waves in lossy media for finite and infinite regions. For infinite regions they are given by two essentially different infinite series, one converging extremely rapidly for small times, one for large times. In the limit of infinite light velocity one obtains diffusing fields in terms of θ-functions, discussed in a preceding paper [1]. They can also be represented by two essentially different infinite series related to one another by Jacobi-transformations. So the present paper generalises the results of the earlier one.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Electrical engineering 79 (1996), S. 297-301 
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Übersicht Es wurde behauptet, daß zu den Differentialoperatoren Δ−1, grad, div und rot inverse Operatoren Δ, grad−1, div−1 und rot−1 existierten [1–3]. Dem wird widersprochen, und es wird gezeigt, welche Konsequenzen die Anwendung dieser angeblich inversen Operatoren hätte. Weiter wird ausgeführt, daß und wie alle hier zu diskutierenden Fragen insbesondere durch das Helmholtzsche Theorem vollständig und elegant gelöst sind.
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  • 14
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents If 3-dimensional electromagnetic problems are solved by finite elements, the computation of the fields for problems involving infinite space causes difficulties. To treat such problems either infinite elements [1] or so called ‘ballooning elements’ [2] can be used. Another possibility is the coupling of finite elements and boundary elements. In this article the calculation of electrostatic and magnetostatic fields in infinite space is presented, utilizing coupled elements. The problems are formulated in terms of potentials. In the electrostatic case the scalar potential ϕ and in the magnetostatic case the vector potentialA is used. To investigate the capability of the coupled elements, among other things two examples have been calculated and compared to their solutions gained with the help of Biot-Savart's law.
    Notes: Übersicht Will man elektromagnetische Probleme, die auf unendlichen Grundgebieten definiert sind, mit Hilfe der Methode der finiten Elemente lösen, so bereitet die Berücksichtigung der unendlichen Grundgebiete Schwierigkeiten. Um diese Schwierigkeiten zu überwinden, kann man beispielsweise zusätzlich infinite Elemente [1] oder sog. “Ballooning-Elemente” [2] verwenden. Eine andere Möglichkeit ist die Kopplung der Methode der finiten Elemente mit der Randelementmethode [4]. In diesem Artikel wird die Berechnung elektrostatischer und magnetischer Felder im unendlichen Raum mit Hilfe einer solchen Hybridmethode vorgestellt. Die Probleme werden entweder mit dem skalaren elektrischen Potential ϕ oder mit dem magnetischen Vektorpotential A formuliert. Um die Leistungsfähigkeit des Hybridansatzes zu untersuchen, werden u. a. zwei Beispiele behandelt, und deren Ergebnisse werden mit den nach dem Biot-Savart'schen Gesetz gewonnenen Lösungen vergleichen.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 207 (1967), S. 83-104 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The neutrons formd—d-reactions in a hot deuterium plasma can be used for plasma diagnostic purposes. The ion velocity distribution is responsible both for the total rate of neutron production and the energy spectrum of the neutrons. Anisotropic velocity distributions give rise to neutron fluxes and neutron energy spectra which are also anisotropic. These effects are discussed for generalized Maxwellian distributions (characterised by different parallel and perpendicular “temperatures”) and for monoenergetic distributions (three-dimensional and two-dimensional), which serve as typical examples.
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  • 16
    Electronic Resource
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    Springer
    The European physical journal 232 (1970), S. 174-189 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Total reaction rates and energy spectra of the generated particles are discussed for fusion reactions in high energy plasmas. Examples, discussed in some detail, concern elliptic and monoenergetic velocity distributions of the plasma. One obtains energy spectra with very typical shapes which should be useful for diagnostic purposes. This is true in particular, of reactions between different particles such as thed-t reaction.
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  • 17
    Electronic Resource
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    Springer
    The European physical journal 232 (1970), S. 405-414 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In the following paper we discuss the possibility of measuring magnetic fields by scattered light. In the case of uncorrelated electrons (i.e. α ≪1) the electron spectrum is modulated with the electron gyration frequency if a certain condition is fulfilled. The essential parameters are discussed and some spectra are computed numerically.
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  • 18
    Electronic Resource
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    Springer
    The European physical journal 216 (1968), S. 488-498 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The relaxation of a strongly anisotropic two-component-plasma is treated by using the Balescu-Lenard-equation, i.e. taking into account collective effects. The relaxation process is described by parallel and perpendicular temperatures as functions of time; it is assumed that the distribution functions remain elliptical. The result is that collective effects are only significant if the ratio of electron and ion temperatures is very small (〈10−4) or very large (〉10+2).
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 206 (1967), S. 284-292 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The relaxation of anisotropic plasmas due to collisions between two kinds of particles is discussed on the basis of the Fokker-Planck equation, i.e. collective interactions are not taken into account. An initially elliptic distribution is assumed to remain elliptic during the relaxation process. This is the only approximation made, i.e. the usual restriction to small anisotropy is avoided.
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  • 20
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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