[en] The two Coulomb centers problem in a complex plane of an internuclear distance R is considered as a system of the nonlinear equations. The system, which arises at use of a finite-difference method, is solved by the Newton's method with the use of LU-decomposition of the system matrix. At an evaluation of the LU-decomposition and solution of the system the regularization was applied

No abstract available

[en] In the solution of large-scale numerical prob- lems, parallel computing is becoming simultaneously more important and more difficult. The complex organization of today's multiprocessors with several memory hierarchies has forced the scientific programmer to make a choice between simple but unscalable code and scalable but extremely com- plex code that does not port to other architectures. This paper describes how the SMARTS runtime system and the POOMA C++ class library for high-performance scientific computing work together to exploit data parallelism in scientific applications while hiding the details of manag- ing parallelism and data locality from the user. We present innovative algorithms, based on the macro -dataflow model, for detecting data parallelism and efficiently executing data- parallel statements on shared-memory multiprocessors. We also desclibe how these algorithms can be implemented on clusters of SMPS

[en] This paper reports progress on implementing a new capability of adaptive mesh refinement into the Eulerian multimaterial shock- physics code CTH. The adaptivity is block-based with refinement and unrefinement occurring in an isotropic 2:1 manner. The code is designed to run on serial, multiprocessor and massive parallel platforms. An approximate factor of three in memory and performance improvements over comparable resolution non-adaptive calculations has-been demonstrated for a number of problems

[en] The phenomena of transient movements have an wavy character due to the pipe elasticity, inertia and compressibility of the fluid. Disturbances of the boundary conditions would result in local and pressure changes which are further transferred through waves along the whole hydraulic installation. A program based of the method of wave superposition was developed and implemented on PC/386 computers. The program was applied for analysis of water hammer shock effects in the Emergency Core Cooling System at the Nuclear Power Plant Cernavoda

[en] The paper proposes an algorithms to reduce the memory size of look-up tables, when adding and subtracting numbers in the Redundant Logarithmic Number System, which requires voluminous look-up table especially when adding numbers. In the look-up tables are saved only curvature points in the function s_b(z). The point values between two curvature points, required for addition and subtraction, are calculated with a cubic spline interpolation for unequally spaced points. Since the cubic spline interpolation involves a lot of multiplications and divisions, logarithmic arithmetic is used in multiplications and divisions to be implemented easily in hardware. (Author)

[en] A computer program is presented that translates logic equations into promburner files (or the reverse) for programmable logic devices of various kinds, namely PROMs FPLAs, FPLSs and PALs. The program achieves flexibility through the use of a database containing detailed information about the devices to be programmed. New devices can thus be accommodated through simple extensions of the database. When writing logic equations, the user can define logic combinations of signals as new logic variables for use in subsequent equations. This procedure yields compact and transparent expressions for logic operations, thus reducing the chances for error. A logic simulation program is also provided so that an independent check of the design can be performed at the software level

[en] The plasticity of crystalline solids results from the motion of linear defects, the dislocations. A potential exists for the development of numerical methods in this domain, as a consistent theoretical description of plasticity, from the atomic scale to the scale of the bulk material is presently beyond reach. The emphasis is put here on simulations at the mesoscopic scale, i.e. at the scale of the dislocation microstructure. After a brief review of the current state of the art, an application to dislocation patterning during cyclic deformation is outlined. (orig.)

[en] The structure of topological theory coupled to topological gravity is studied. We show that in this theory Q-exact terms do not decouple. This not decoupling in the action of the theory is connected with the existence of boundaries of the moduli space and leads to problems in defining the topological gravity for massive topological theories. Not decoupling of Q-exact observables leads to filtration of the gravitational descendants constructed from matter fields. Two a priori different preferred splittings of this filtration are constructed (one connected with the massive deformation of the theory and the other connected with the flatness of the connection on the space of theories). It is conjectured that they coincide

[en] This work deals with the problem of output robust stabilization of uncertain discrete systems with matched uncertainties. In the continuous case, the problem of the existence of an output min-max controller for systems with matched uncertainties was treated extensively and has been fully resolved. It was shown that an output min-max controller exists if and only if there exists a feedback gain matrix that makes the nominal system strictly positive real. It was found that if the system is minimum phase and has a high frequency gain with a full column rank, then there exists an output controller that makes the system. These results have motivated this work that presents a comprehensive solution to the problem of the existence of an output discrete min-max controller (static and dynamic) for multiple input multiple output systems which can be stabilized and are detectable. The question of the existence of an output feedback gain, K, that assures that for the resulting closed loop there exists a static output LMMC is investigated. For square systems an extremely simple criterion is derived. For non square systems, the condition involves searching for the matrix W that assures that asymptotically stabilized the system. Conditions for the existence of a static output RMMC are also investigated. 44 refs