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 - JOUR A1 - Gerber, Stefan A1 - Gössel, Michael T1 - Detection of permanent faults of a floating point adder by pseudoduplication Y1 - 1994 ER - TY - JOUR A1 - Gössel, Michael A1 - Sogomonyan, Egor S. T1 - Self-parity combinational-circuits for self-testing, concurrent fault-detection and parity scan design Y1 - 1994 ER - TY - JOUR A1 - Bogue, Ted A1 - Jürgensen, Helmut A1 - Gössel, Michael T1 - Design of cover circuits for monitoring the output of a MISR Y1 - 1994 SN - 0-8186-6307-3 , 0-8186-6306-5 ER - TY - JOUR A1 - Gössel, Michael A1 - Sogomonyan, Egor S. T1 - Code disjoint self-parity combinational circuits for self-testing, concurrent fault detection and parity scan design Y1 - 1994 ER - TY - JOUR A1 - Gössel, Michael A1 - Morosov, Andrej A1 - Saposhnikov, V. V. A1 - Saposhnikov, VL. V. T1 - Design of combinational self-testing devices with unidirectionally independent outputs Y1 - 1994 ER - TY - JOUR A1 - Crome, Erhard A1 - Franzke, Jochen T1 - Towards an East German party system? : the local elections in Brandenburg in 1993 Y1 - 1994 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 - Köberle, Peter A1 - Laschewsky, André T1 - Hybrid materials from organic polymers and inorganic salts N2 - The prepaparation of amorphous, homogeneous blends of zwitterionic polymers and transition metal salts was investigated. Homogeneous miscibility was achieved in many cases up to equimolar amounts of salt, depending on the anion and cation chosen. Various analytical techniques point to a solid state solution of the inorganic ions in the polymer matrix. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 086 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-26884 ER - TY - GEN A1 - Selting, Margret T1 - Question intonation revisited : the intonation of conversational questions N2 - Content: 1. Introduction 2. Aim and approach of the present analysis 3. Non-restrictive 'open' conversational questions 4. More restrictive "narrower" questions 5. "Deviant cases" 6. Conclusions T3 - Zweitveröffentlichungen der Universität Potsdam : Philosophische Reihe - 66 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-43179 ER - TY - INPR A1 - Witt, Annette A1 - Kurths, Jürgen A1 - Krause, F. A1 - Fischer, K. T1 - On the validity of a model for the reversals of the Earth‘s magnetic field N2 - We have used techniques of nonlinear dynamics to compare a special model for the reversals of the Earth's magnetic field with the observational data. Although this model is rather simple, there is no essential difference to the data by means of well-known characteristics, such as correlation function and probability distribution. Applying methods of symbolic dynamics we have found that the considered model is not able to describe the dynamical properties of the observed process. These significant differences are expressed by algorithmic complexity and Renyi information. T3 - NLD Preprints - 4 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-13460 ER - TY - INPR A1 - Kurths, Jürgen A1 - Voss, A. A1 - Witt, Annette A1 - Saparin, P. A1 - Kleiner, H. J. A1 - Wessel, Niels T1 - Quantitative analysis of heart rate variability N2 - In the modern industrialized countries every year several hundred thousands of people die due to the sudden cardiac death. The individual risk for this sudden cardiac death cannot be defined precisely by common available, non-invasive diagnostic tools like Holter-monitoring, highly amplified ECG and traditional linear analysis of heart rate variability (HRV). Therefore, we apply some rather unconventional methods of nonlinear dynamics to analyse the HRV. Especially, some complexity measures that are basing on symbolic dynamics as well as a new measure, the renormalized entropy, detect some abnormalities in the HRV of several patients who have been classified in the low risk group by traditional methods. A combination of these complexity measures with the parameters in the frequency domain seems to be a promising way to get a more precise definition of the individual risk. These findings have to be validated by a representative number of patients. T3 - NLD Preprints - 5 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-13470 ER - TY - JOUR A1 - Eisenberg, Peter T1 - German Y1 - 1994 ER -