15 Fakultätsübergreifend / Sonstige Einrichtung

Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/16

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Publication Type: search.filters.UBSTyp.KonferenzbeitragAuthor: search.filters.author.Ruder, Hanns

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    Self-consistent modelling of pulsar magnetospheres
    (1989) Herold, Heinz; Ertl, Thomas; Finkbeiner, Bernd; Ruder, Hanns
    The magnetosphere of a rapidly rotating, strongly magnetized neutron star with aligned magnetic and rotational axes (parallel rotator) is modelled numerically. Including the radiation of the particles accelerated to relativistic energies as an efficient damping mechanism, we obtain a quasi-stationary selfconsistent solution to this classical problem. The numerical simulation, which was started from the well-known vacuum solution, yields a global magnetospheric structure that can be characterized by two regions of oppositely charged particles, which eventually produce a relativistic pulsar wind, separated by a vacuum gap of considerable extent.
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    Simulation mit Supercomputern : ein neues Werkzeug der Physik
    (1990) Ruder, Hanns; Ertl, Thomas; Geyer, Florian; Herold, Heinz; Kraus, Ute; Nollert, Hans-Peter; Rebetzky, Andreas; Schweizer, Wolfgang; Zahn, Corvin
    Unser Wissen über die Struktur des Kosmos und die darin enthaltenen Objekte stammt aus der sorgfältigen Analyse der auf der Erde einfallenden elektromagnetischen Strahlung,verbunden mit einer theoretischen Modellierung im Rahmen der von uns erforschten Naturgesetze. Die sprunghafte Zunahme unserer Kenntnisse in den letzten zwei Jahrzehnten verdanken wir vor allem den vielen Forschungssatelliten, die die Beobachtung kosmischer Objekte ohne die störenden Einflüsse unserer Atmosphäre erlauben. Speziell im weichen Röntgenbereich ist dadurch eine Beobachtung überhaupt erst möglich , und es ist gerade dieser Spektralbereich, der uns wesentlich neue Erkenntnisse über hochinteressante Objekte geliefert hat, da intensive Röntgenstrahlung nur unter sehr extremen physikalischen Bedingungen entsteht. Die in diesen Röntgenemissionsgebieten vorherrschenden Temperaturen, Magnet- und Gravitationsfelder sind so extrem, daß sie in irdischen Labors nicht realisiert werden können. Folglich bleibt nur die Möglichkeit, die Eigenschaften der Materie und die unter diesen Bedingungen ablaufenden physikalischen Prozesse theoretisch zu berechnen, um so - im Vergleich mit den Beobachtungen - zu zuverlässigen Aussagen über die Struktur dieser kosmischen Objekte zu gelangen.
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    Kinematics and dynamics for computer animation
    (1994) Ruder, Hanns; Ertl, Thomas; Gruber, Karin; Günther, Michael; Hospach, Frank; Ruder, Margret; Subke, Jörg; Widmayer, Karin
    This tutorial will focus on the physical principles of kinematics and dynamics. After explaining the basic equations for point masses and rigid bodies a new approach for the dynamic simulation of multi-linked models with wobbling mass is presented, which has led to new insight in the field of biomechanics, but which has not been used in computer animation so far.
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    Towards a self-consistent modelling of pulsar magnetospheres
    (1987) Herold, Heinz; Ertl, Thomas; Finkbeiner, Bernd; Ruder, Hanns
    The numerical modelling of the general case of an oblique rotator is a very complicated time-dependent 3-dimensional problem and in its full extent probably outside the capicity of present.day computers. A considerable simplification occurs if one can assume that the essential effects may be understood by modelling the magnetosphere of an aligned rotator (where the rotation axis is parallel to the magnetic axis of the neutron star). This assumption is only reasonable for small obliqueness, since by this approach all electromagnetic wave effects are not taken into account.
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    Towards a self-consistent modelling of pulsar magnetospheres
    (1986) Herold, Heinz; Ertl, Thomas; Ruder, Hanns
    The numerical modelling of the general case of an obligue rotator is a very complicated time-dependent three-dimensional problem and in its full extent probably outside the capacity of present-day computers. A considerable simplification occurs if one can assume that the essential effects may be understood by modelling the magnetosphere of an aligned rotator (where the rotation axis is parallel to the magnetic axis of the neutron star). This assumption is only reasonable for small obliguenses, since by this approach all electromagnetic wave effects are not taken into account. An advantage, however, is that unipolar induction, which should be responsible for populsting the magnetosphere with charged particles pulled out from the neutron star surface via field emission, can be studied purity.
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    Interactive control of biomechanical animation : contribution to the GI Workshop: Visualisierung - Rolle von Interaktivitat und Echtzeit, GMD, Sankt Augustin, 2.-3. Juni 1992
    (1992) Ertl, Thomas; Ruder, Hanns; Gruber, Karin; Günther, Michael; Hospach, Frank; Krebs, Thomas; Subke, Jörg; Widmayer, Karin
    Physical based animation can be generated by performing a complete dynamical simulation of multi-body systems. This leads to a complex system of differential equations which has to be solved incorporating biomechanical results for the physics of impacts. Motion control is achieved by interactively modifying the internal torques. Realtime response requires the distribution of the workload of the computation between a highspeed computerserver and the graphics workstation by means of a remote procedure call mechanism.
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    Analysis of hydrogen Rydberg spectra in a uniform magnetic field: uncovering the transition from regularity to irregularity in a real quantum system
    (1986) Wunner, Günter; Woelk, Ulrich; Zech, Ingrid; Zeller, Gudrun; Ertl, Thomas; Geyer, Florian; Steitz, Arno; Schweizer, Wolfgang; Ruder, Hanns
    Studies of the behaviour of quantum systems in a range of energy where their classical counterparts undergo transitions from regularity to irregularity, as manifested in phase space by the gradual destruction of invariant tori, to date have largely been confined to model Hamiltonian systems such as harmonic oscillators with cubic, quartic, or higher-degree polynomial corrections, or the stadium problem. We show that phenomena which have turned out characteristic of the onset of "quantum stochasticity" in these model systems can in fact be recovered in the quantal energy spectra of a "real" physical system, viz. spectra of hydrogen Rydberg atoms in strong magnetic fields. This implies that one has a simple prototype system at hand in which to study - not only in theory but also in experiment, quantitatively and in detail, and as a function of a continuously tunable external parameter - phenomena that are expected to be typical of the quantum properties of nonintegrable systems in general.
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    Self-consistent numerical modelling of pulsar magnetospheres
    (1992) Herold, Heinz; Ertl, Thomas; Finkbeiner, Bernd; Ruder, Hanns
    The magnetosphere of a rapidly rotating, strongly magnetized neutron star with aligned magnetic and rotational axes (parallel rotator) is modelled numerically. Including the radiation of the particles accelerated to relativistic energies as an efficient damping mechanism, we obtain a quasi-stationary self-consistent solution to this classical problem. The numerical simulation,which was started from the well-known vacuum solution, yields a global magnetospheric structure that can be characterized by two regions of oppositely charged particles, which eventually produce a relativistic pulsar wind, separated by a vacuum gap of considerable extent.
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    Computersimulation in der Astrophysik
    (1990) Ruder, Hanns; Ertl, Thomas; Geyer, Florian; Herold, Heinz; Kraus, Ute; Nollert, Hans-Peter; Rebetzky, Andreas; Zahn, Corvin
    Unser Wissen über die Struktur des Kosmos und die darin enthaltenen Objekte stammt aus der sorgfältigen Analyse der einfallenden elektromagnetischen Strahlung, verbunden mit einer theoretischen Modellierung im Rahmen der von uns erforschten Naturgesetze. Die Beobachtungen erstrecken sich dabei heute vom Radiowellenbereich über den Infrarot-, den optischen, den Röntgenbereich bis hin zum Höchstenergie-Gamma-Bereich, also über mehr als 20 Dekaden des elektromagnetischen Spektrums. Eine realistische Modellierung der Systeme im Rahmen einer beobachtungsnahen Theorie erfordert vor allem bei Systemparameterstudien im allgemeinen den Einsatz der größten verfügbaren Rechenleistungen.
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    Visualization in astrophysics
    (1989) Ertl, Thomas; Geyer, Florian; Herold, Heinz; Kraus, Ute; Niemeier, Roland; Nollert, Hans-Peter; Rebetzky, Andreas; Ruder, Hanns; Zeller, Gudrun
    This paper reports on progress we have made in modelling cosmic X·ray sources on supercomputers. The results we present are meant to serve as an example for the fact that sophisticated visualization techniques play a crucial role in scientific computing. Among the graphical methods we demonstrate, raytracing in curved space-time and a physically motivated 3D-volume rendering algorithm might be of interest to the graphics community in general.