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  • 1
    Electronic Resource
    Electronic Resource
    A fast interface solver for the biharmonic Dirichlet problem on polygonal domains (1998)
    Springer
    Numerische Mathematik 78 (1998), S. 577-596 
    Details
    ISSN: 0945-3245
    Keywords: Mathematics Subject Classification (1991): 31A30, 35J40, 65N30, 65N12
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary. In this paper we propose and analyze an efficient discretization scheme for the boundary reduction of the biharmonic Dirichlet problem on convex polygonal domains. We show that the biharmonic Dirichlet problem can be reduced to the solution of a harmonic Dirichlet problem and of an equation with a Poincaré-Steklov operator acting between subspaces of the trace spaces. We then propose a mixed FE discretization (by linear elements) of this equation which admits efficient preconditioning and matrix compression resulting in the complexity $\log \varepsilon^{-1} O ( N \log^qN)$ . Here $N$ is the number of degrees of freedom on the underlying boundary, $\varepsilon 〉 0$ is an error reduction factor, $q = 2$ or $q = 3$ for rectangular or polygonal boundaries, respectively. As a consequence an asymptotically optimal iterative interface solver for boundary reductions of the biharmonic Dirichlet problem on convex polygonal domains is derived. A numerical example confirms the theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002110050326
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  • 2
    Electronic Resource
    Electronic Resource
    Design Issues of a Semi-Autonomous Robotic Assistant for the Health Care Environment (1998)
    Springer
    Journal of intelligent and robotic systems 22 (1998), S. 191-209 
    Details
    ISSN: 1573-0409
    Keywords: robotic assistant ; mobile service robot ; health care ; fetch-and-carry task ; mobile manipulation ; human-robot interface ; augmented virtual workspace
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper discusses design issues of a mobile robotic assistant for health or home care applications with the objective of relieving hospital personnel or domestic users of time-consuming routine tasks. These tasks are delegated to the robot via natural language and in turn autonomously executed. With respect to the execution of typical fetch-and-carry tasks, key components are surveyed and a system architecture for integration of the individual hardware and software modules into a service robot is presented. A prototype implementation is described and used for demonstrating the performance of the proposed design approach in real-world service scenarios.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008082024638
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of acute administration of ethanol and the μ-opiate agonist etonitazene on thyroid hormone metabolism in rat brain (1998)
    Springer
    Psychopharmacology 135 (1998), S. 63-69 
    Details
    ISSN: 1432-2072
    Keywords: Key wordsEthanol ; Etonitazene ; Deiodinases ; Thyroid hormones ; Rat brain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of acute, low-dose administration of ethanol (1 g/kg bodyweight) and the μ-opioid receptor agonist etonitazene (30 μg/kg bodyweight) on the activities of the iodothyronine deiodinase isoenzymes were investigated in nine regions of the rat brain. The experiments were performed at three different times of the 24-h cycle (1300, 2100 and 0500 hours) and the rats were decapitated 30 and 120 min after administration of the respective drugs. Interest was focused on changes in the two enzymes that catalyze 1) 5′-deiodination of thyroxine (T4) to the biologically active triiodothyronine (T3), i.e. type II 5′-deiodinase (5′D-II) and 2) 5 (or inner-ring) deiodination of T3 to the biologically inactive 3′3-T2, i.e. type III deiodinase (5D-III). 120 min after administration of ethanol and etonitazene 5D-III activity was selectively inhibited in the frontal cortex (at 1300 and 1700 hours) and the amygdala (at all three measuring times). The 5′D-II activity was significantly enhanced 30 min after administration of etonitazene in the frontal cortex, amygdala and limbic forebrain, and after administration of ethanol in the amygdala alone. These effects on 5′D-II activity were seen at 2100 hours only. In conclusion, the two different addictive drugs both reduced the inactivation of the physiologically active thyroid hormone T3 and enhanced its production. These effects occurred almost exclusively in the brain regions which were most likely to be involved in the rewarding properties of addictive drugs. As thyroid hormones have stimulating and mood-elevating properties, an involvement of these hormones in the reinforcing effects of addictive drugs seems conceivable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050486
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  • 4
    Electronic Resource
    Electronic Resource
    Diffraction in periodic structures and optimal design of binary gratings. Part I: direct problems and gradient formulas (1998)
    Chichester, West Sussex : Wiley-Blackwell
    Mathematical Methods in the Applied Sciences 21 (1998), S. 1297-1342 
    Details
    ISSN: 0170-4214
    Keywords: Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: The aim of the paper is to provide the mathematical foundation of effective numerical algorithms for the optimal design of periodic binary gratings. Special attention is paid to reliable methods for the computation of diffraction efficiencies and of the gradients of certain functionals with respect to the parameters of the non-smooth grating profile. The methods are based on a generalized finite element discretization of strongly elliptic variational formulations of quasi-periodic transmission problems for the Helmholtz equation in a bounded domain coupled with boundary integral representations in the exterior. We prove uniqueness and existence results for quite general situations and analyse the convergence of the numerical solutions. Furthermore, explicit formulas for the partial derivatives of the reflection and transmission coefficients with respect to the parameters of a binary grating profile are derived. Finally, we briefly discuss the implementation of the generalized finite element method for solving direct and adjoint diffraction problems and present some numerical results. © 1998 B. G. Teubner Stuttgart - John Wiley & Sons, Ltd.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Polymeranaloge Umsetzungen an Copolymeren mit Maleinsäureanhydrid in der Schmelze (1998)
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 70 (1998), S. 560-566 
    Details
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cite.330700515
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    Paper (German National Licenses)
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