TY - JOUR A1 - Denecke, Klaus-Dieter T1 - On the characterization of primal partial algebras by strong regular hyperidentities Y1 - 1994 ER - TY - JOUR A1 - Denecke, Klaus-Dieter A1 - Halkowska, Katarzcyna T1 - P-compatible hybrid-identities and hyperidentities Y1 - 1994 ER - TY - JOUR A1 - Denecke, Klaus-Dieter A1 - Malcev, I. A. T1 - Separation of clones by means of hyperidentities Y1 - 1994 ER - TY - JOUR A1 - Denecke, Klaus-Dieter A1 - Wismath, Shelly T1 - Solid varieties of semigroups Y1 - 1994 ER - TY - JOUR A1 - Denecke, Klaus-Dieter A1 - Koppitz, Jörg T1 - Hyperassociative semigroups Y1 - 1994 ER - TY - JOUR A1 - Denecke, Klaus-Dieter T1 - Pre-solid varieties Y1 - 1994 ER - TY - BOOK A1 - Denecke, Klaus-Dieter A1 - Todorov, Kalco T1 - Algebraische Grundlagen der Arithmetik T3 - Berliner Studienreihe zur Mathematik Y1 - 1994 VL - 4 PB - Heldermann CY - Berlin ER - TY - GEN A1 - Ascher, Uri M. A1 - Chin, Hongsheng A1 - Reich, Sebastian T1 - Stabilization of DAEs and invariant manifolds N2 - Many methods have been proposed for the stabilization of higher index differential-algebraic equations (DAEs). Such methods often involve constraint differentiation and problem stabilization, thus obtaining a stabilized index reduction. A popular method is Baumgarte stabilization, but the choice of parameters to make it robust is unclear in practice. Here we explain why the Baumgarte method may run into trouble. We then show how to improve it. We further develop a unifying theory for stabilization methods which includes many of the various techniques proposed in the literature. Our approach is to (i) consider stabilization of ODEs with invariants, (ii) discretize the stabilizing term in a simple way, generally different from the ODE discretization, and (iii) use orthogonal projections whenever possible. The best methods thus obtained are related to methods of coordinate projection. We discuss them and make concrete algorithmic suggestions. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 030 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-15625 ER - TY - GEN A1 - Leimkuhler, Benedict A1 - Reich, Sebastian T1 - Symplectic integration of constrained Hamiltonian systems N2 - A Hamiltonian system in potential form (formula in the original abstract) subject to smooth constraints on q can be viewed as a Hamiltonian system on a manifold, but numerical computations must be performed in Rn. In this paper methods which reduce "Hamiltonian differential algebraic equations" to ODEs in Euclidean space are examined. The authors study the construction of canonical parameterizations or local charts as well as methods based on the construction of ODE systems in the space in which the constraint manifold is embedded which preserve the constraint manifold as an invariant manifold. In each case, a Hamiltonian system of ordinary differential equations is produced. The stability of the constraint invariants and the behavior of the original Hamiltonian along solutions are investigated both numerically and analytically. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 032 KW - differential-algebraic equations KW - constrained Hamiltonian systems KW - canonical discretization schemes KW - symplectic methods Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-15653 ER - TY - GEN A1 - Ascher, Uri M. A1 - Chin, Hongsheng A1 - Petzold, Linda R. A1 - Reich, Sebastian T1 - Stabilization of constrained mechanical systems with DAEs and invariant manifolds N2 - Many methods have been proposed for the simulation of constrained mechanical systems. The most obvious of these have mild instabilities and drift problems. Consequently, stabilization techniques have been proposed A popular stabilization method is Baumgarte's technique, but the choice of parameters to make it robust has been unclear in practice. Some of the simulation methods that have been proposed and used in computations are reviewed here, from a stability point of view. This involves concepts of differential-algebraic equation (DAE) and ordinary differential equation (ODE) invariants. An explanation of the difficulties that may be encountered using Baumgarte's method is given, and a discussion of why a further quest for better parameter values for this method will always remain frustrating is presented. It is then shown how Baumgarte's method can be improved. An efficient stabilization technique is proposed, which may employ explicit ODE solvers in case of nonstiff or highly oscillatory problems and which relates to coordinate projection methods. Examples of a two-link planar robotic arm and a squeezing mechanism illustrate the effectiveness of this new stabilization method. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 033 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-15698 ER - TY - GEN A1 - Reich, Sebastian T1 - Momentum conserving symplectic integrators N2 - In this paper, we show that symplectic partitioned Runge-Kutta methods conserve momentum maps corresponding to linear symmetry groups acting on the phase space of Hamiltonian differential equations by extended point transformation. We also generalize this result to constrained systems and show how this conservation property relates to the symplectic integration of Lie-Poisson systems on certain submanifolds of the general matrix group GL(n). T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 044 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-16824 ER - TY - BOOK A1 - Schmidt, Hans-Jürgen T1 - Why do all the curvature invariants of a gravitational wave vanish? T3 - Preprint / Universität Potsdam, Institut für Mathematik Y1 - 1994 VL - 1994, 03 PB - Univ. CY - Potsdam ER - TY - BOOK A1 - Jonas, Peter A1 - Langer, Heinz T1 - Selfadjoint extensions of a closed linear realtion of defect one in a Krein space. Universität Potsdam, Fachbereich Mathematik T3 - Preprint / Universität Potsdam, Institut für Mathematik Y1 - 1994 VL - 1994, 17 PB - Univ. CY - Potsdam ER - TY - BOOK A1 - Dahlke, Stephan A1 - Maaß, Peter T1 - The affine uncertainty principle in one and two dimensions T3 - Preprint / Universität Potsdam, Fachbereich Mathematik Y1 - 1994 VL - 1994, 01 PB - Univ. CY - Potsdam ER - TY - BOOK A1 - Wollenberg, Manfred T1 - On an inverse problem in modular theory T3 - Preprint / Universität Potsdam, Institut für Mathematik Y1 - 1994 VL - 1994, 07 PB - Univ. CY - Potsdam ER - TY - BOOK A1 - Dahlke, Stephan A1 - Maaß, Peter T1 - A continuous wavelet transform on tangent bundles of spheres T3 - Preprint / Universität Potsdam, Institut für Mathematik Y1 - 1994 VL - 1994, 16 PB - Univ. CY - Potsdam ER - TY - BOOK A1 - Quaisser, Erhard T1 - Die Symmetriestruktur von Figuren T3 - Preprint / Universität Potsdam, Institut für Mathematik Y1 - 1994 VL - 1994, 08 CY - Potsdam ER - TY - BOOK A1 - Kasper, Uwe T1 - On first class sonstraints of simple cosmological models in Einstein's gravity theory T3 - Preprint / Universität Potsdam, Institut für Mathematik Y1 - 1994 VL - 1994, 10 PB - Univ. CY - Potsdam ER - TY - BOOK A1 - Schmidt, Hans-Jürgen T1 - Stability and Hamiltonian formulation of higher derivative theories T3 - Preprint / Universität Potsdam, Institut für Mathematik Y1 - 1994 VL - 1994, 04 PB - Univ. CY - Potsdam ER - TY - BOOK A1 - Reuter, Stefan A1 - Schmidt, Hans-Jürgen T1 - Klassisch konformäquivalente Gravitationstheorien und deren korrespondierende Wheeler-de-Witt-Gleichungen T3 - Preprint / Universität Potsdam, Institut für Mathematik Y1 - 1994 VL - 1994, 05 PB - Univ. CY - Potsdam ER - TY - BOOK A1 - Rainer, Martin T1 - Conformal minisuperspace quantization and equivalence of multidimensional classical and quantum models : lecuture presented at the International Conference on Multidimensional Cosmology, Jaroslavl, June 20-26, 1994 T3 - Preprint / Universität Potsdam, Institut für Mathematik Y1 - 1994 VL - 1994, 09 PB - Univ. CY - Potsdam ER - TY - JOUR A1 - Alpers, Karsten T1 - Über zweidimensionale diskrete Bewegungsgruppen der pseudoeuklidischen Ebene Y1 - 1994 ER - TY - BOOK A1 - Baumgärtel, Hellmut T1 - A modified approach to the Doplicher-Roberts theorem on the construction of field algebra and the symmetry group in superselection theory T3 - Preprint / SFB 288, Differentialgeometrie und Quantenphysik Y1 - 1994 VL - 134 CY - Berlin ER - TY - BOOK A1 - Bölling, Reinhard T1 - Das Fotoalbum für Weierstraß = A photoalbum for Weierstrass Y1 - 1994 PB - Vieweg CY - Braunschweig [u.a.] ER - TY - JOUR A1 - Bölling, Reinhard T1 - Karl Weierstraß - Stationen eines Lebens Y1 - 1994 ER - TY - BOOK A1 - Kasper, Uwe T1 - On the Hamilton formalism for cosmological models in fourth order gravity theories T3 - Preprint / Universität Potsdam, Institut für Mathematik Y1 - 1994 VL - 1994, 11 CY - Potsdam ER - TY - BOOK A1 - Neidhardt, Hagen A1 - Zagrebnov, Valentin A. ED - Demuth, Michael ED - Exner, Pavel T1 - Mathematical results in quantum mechanics : international conference in Blossin (Germany), May 17 - 21, 1993 T3 - Operator Theory Y1 - 1994 VL - 70 PB - Birkhäuser CY - Basel ER - TY - JOUR A1 - Gähler, Siegfried A1 - Gähler, Werner T1 - Fuzzy real numbers Y1 - 1994 ER - TY - JOUR A1 - Gähler, Werner T1 - Die Theorie der Kontinua : ein Gebiet, in dem die Anschauung teilweise versagt Y1 - 1994 ER - TY - JOUR A1 - Schmidt, Hans-Jürgen A1 - Baier, Frank W. A1 - Bleyer, Ulrich A1 - Hubrig, Swetlana A1 - Meister, Claudia-Veronika A1 - Schilbach, Elena A1 - Tiersch, Heinz T1 - Zum Wissenschaftler-Integrationsprogramm Y1 - 1994 ER - TY - JOUR A1 - Louis, Alfred K. A1 - Maaß, Peter A1 - Rieder, Andreas A1 - Stark, H.-G. T1 - Wavelets and digital image processing Y1 - 1994 ER - TY - JOUR A1 - Jaksic, V. A1 - Jung, K. A1 - Klein, Markus A1 - Seiler, R. T1 - Corrections to quantized charge transport in quantum hall systems Y1 - 1994 ER - TY - BOOK A1 - Baumgärtel, Hellmut A1 - Jurke, Matthias A1 - Lledó, Fernando T1 - A remark on covariant and causal nets of CAR-resp.CCR-type local algebras assigned to the irreducible unitary representation of the poincare group labeled by (m>0, s, +) T3 - Preprint / SFB 288, Differentialgeometrie und Quantenphysik Y1 - 1994 VL - 120 CY - Berlin ER - TY - JOUR A1 - Jahnke, Thomas A1 - Wippermann, Christina T1 - Vernünftig bremsen und rechnen! : zehn Aufgaben für Bahn-, Auto- und Radfahrer Y1 - 1994 ER - TY - JOUR A1 - Jahnke, Thomas A1 - Wippermann, Christina T1 - Weg, Geschwindigkeit und Beschleunigung im Mathematikunterricht Y1 - 1994 ER - TY - JOUR A1 - Klein, Markus T1 - Hall conductance of Riemann surfaces Y1 - 1994 ER - TY - JOUR A1 - Klotzek, Benno T1 - Diskontinuierliche Bewegungsgruppen verschiedenen Grades in metrischen Räumen Y1 - 1994 ER - TY - GEN A1 - Klotzek, Benno T1 - Falkner, N., A characterization of inner product spaces Y1 - 1994 ER - TY - GEN A1 - Klotzek, Benno T1 - Stammler, L., Einige Themen im Zusammenhang mit rasterbezogenem Approximieren Y1 - 1994 ER - TY - GEN A1 - Klotzek, Benno T1 - Stärk, R., Beispiele zur Anwendung eines Computeralgebrasystems in der Geometrie Y1 - 1994 ER - TY - BOOK A1 - Baumgärtel, Hellmut A1 - Jurke, Matthias A1 - Lledó, Fernando T1 - Mathematische Strukturen passen auf die Natur : Reflexionen über das Wechselverhältnis von Mathematik und Physik T3 - Preprint / Universität Potsdam, Institut für Mathematik Y1 - 1994 VL - 1994, 18 PB - Univ. CY - Potsdam ER - TY - BOOK A1 - Quaisser, Erhard A1 - Wendland, Horst T1 - Seminar zur Darstellenden Geometrie : Skripte Y1 - 1994 PB - Univ. CY - Potsdam ER - TY - BOOK A1 - Schmidt, Hans-Jürgen T1 - An alternate Hamiltonian formulation of fourth-order theories T3 - Preprint / Universität Potsdam, Institut für Mathematik Y1 - 1994 VL - 1994, 12 PB - Univ. CY - Potsdam ER - TY - BOOK A1 - Quaisser, Erhard T1 - Symmetrie und Symmetriegruppen in der Geometrie : Skripte Y1 - 1994 PB - Univ. CY - Potsdam ER - TY - THES A1 - Reichel, Mario T1 - Bi-Homonorphismen und Hyperidentitäten Y1 - 1994 PB - Univ. CY - Potsdam ER - TY - THES A1 - Rainer, Martin T1 - The topology of the space of real LIE algebras up to dimension 4 with applications to homogeneous cosmological models Y1 - 1994 PB - Univ. ER - TY - BOOK A1 - Louis, Alfred K. A1 - Maaß, Peter A1 - Rieder, Andreas T1 - Wavelets : Theorie und Anwendungen Y1 - 1994 PB - Teubner CY - Stuttgart ER - TY - JOUR A1 - Maaß, Peter T1 - Wavelet galerkin methods for inverse problems Y1 - 1994 ER - TY - JOUR A1 - Neidhardt, Hagen A1 - Zagrebnov, Valentin A. T1 - Singular perturbations, regularization and extension theory Y1 - 1994 ER - TY - BOOK A1 - Quaisser, Erhard T1 - Bewegungsgeometrische Sachverhalte im Raum - unterrichtsrelevant? : Geometrieworkshop, Universität Greifswald, 30.05. - 01.06.1994 ; erweiterter Vortragsauszug Y1 - 1994 PB - Univ. CY - Greifswald ER -