26 research outputs found

    Конкуренция самоорганизованных вращающихся спиральных автоволн в неравновесной диссипативной системе с трехуровневыми активными центрами

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    Методом компьютерного моделирования исследована конкуренция самоорганизованных вращающихся спиральных автоволн (ВСА) в неравновесной диссипативной системе, обладающей возбудимостью и двухканальным механизмом диффузии возбуждений. Система состоит из локально взаимодействующих активных центров (АЦ), свойства которых близки к свойствам АЦ в фазере (микроволновом фононном лазере). При слабой конкуренции ВСА наблюдалась динамическая стабилизация и сосуществование ВСА с различными топологическими зарядами. Для случая сильно конкурирующих ВСА обнаружено самоиндуцированное обращение знака топологического заряда и установлен механизм этого нелинейного явления. Обсуждаются перспективы исследования ВСА в неравновесных диссипативных системах с возбудимыми трехуровневыми АЦ.Методом комп'ютерного моделювання досліджена конкуренція самоорганізованих обертових спіральних автохвиль (ОСА) у нерівноважній дисипативній системі, яка має властивості збуджуваності та двоканальний механізм дифузії збуджень. Система складається із локально взаємодіючих активних центрів (АЦ), що мають властивості близькі до властивостей АЦ у фазері (мікрохвильовому фононному лазері). При слабкій конкуренції ОСА спостерігалась їх динамічна стабілізація та співіснування ОСА з різними топологічними зарядами. У випадку сильно конкурируючих ОСА виявлено самоіндуковане обернення знаку топологічного заряду та встановлено механізм цього нелінійного явища. Обговорюються перспективи дослідження ОСА у нерівноважних дисипативных системах зі збуджуваними трирівневими АЦ.Competition of self-organized rotating spiral autowaves (RSA) is computationally studied in a nonequilibrium dissipative system possessing excitability and the two-channel diffusion of excitations. Such the system consists of locally interacting three-level active centers (AC) having properties close to ones for AC in the phaser (microwave phonon laser). Dynamical stabilization and coexistence of RSA with different topological charges were observed under conditions of their weak competition. A phenomenon of self-induced reversing of the sign of topological charge was revealed for the case of strongly competing RSA; the mechanism of this nonlinear phenomenon is found. Perspectives of investigations of RSA in nonequilibrium dissipative systems with excitable three-level AC are discussed

    Fourth SIAM Conference on Applications of Dynamical Systems

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    Microgravity Science and Applications: Program Tasks and Bibliography for Fiscal Year 1996

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    NASA's Microgravity Science and Applications Division (MSAD) sponsors a program that expands the use of space as a laboratory for the study of important physical, chemical, and biochemical processes. The primary objective of the program is to broaden the value and capabilities of human presence in space by exploiting the unique characteristics of the space environment for research. However, since flight opportunities are rare and flight research development is expensive, a vigorous ground-based research program, from which only the best experiments evolve, is critical to the continuing strength of the program. The microgravity environment affords unique characteristics that allow the investigation of phenomena and processes that are difficult or impossible to study an Earth. The ability to control gravitational effects such as buoyancy driven convection, sedimentation, and hydrostatic pressures make it possible to isolate phenomena and make measurements that have significantly greater accuracy than can be achieved in normal gravity. Space flight gives scientists the opportunity to study the fundamental states of physical matter-solids, liquids and gasses-and the forces that affect those states. Because the orbital environment allows the treatment of gravity as a variable, research in microgravity leads to a greater fundamental understanding of the influence of gravity on the world around us. With appropriate emphasis, the results of space experiments lead to both knowledge and technological advances that have direct applications on Earth. Microgravity research also provides the practical knowledge essential to the development of future space systems. The Office of Life and Microgravity Sciences and Applications (OLMSA) is responsible for planning and executing research stimulated by the Agency's broad scientific goals. OLMSA's Microgravity Science and Applications Division (MSAD) is responsible for guiding and focusing a comprehensive program, and currently manages its research and development tasks through five major scientific areas: biotechnology, combustion science, fluid physics, fundamental physics, and materials science. FY 1996 was an important year for MSAD. NASA continued to build a solid research community for the coming space station era. During FY 1996, the NASA Microgravity Research Program continued investigations selected from the 1994 combustion science, fluid physics, and materials science NRAS. MSAD also released a NASA Research Announcement in microgravity biotechnology, with more than 130 proposals received in response. Selection of research for funding is expected in early 1997. The principal investigators chosen from these NRAs will form the core of the MSAD research program at the beginning of the space station era. The third United States Microgravity Payload (USMP-3) and the Life and Microgravity Spacelab (LMS) missions yielded a wealth of microgravity data in FY 1996. The USMP-3 mission included a fluids facility and three solidification furnaces, each designed to examine a different type of crystal growth

    Generalized averaged Gaussian quadrature and applications

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    A simple numerical method for constructing the optimal generalized averaged Gaussian quadrature formulas will be presented. These formulas exist in many cases in which real positive GaussKronrod formulas do not exist, and can be used as an adequate alternative in order to estimate the error of a Gaussian rule. We also investigate the conditions under which the optimal averaged Gaussian quadrature formulas and their truncated variants are internal

    MS FT-2-2 7 Orthogonal polynomials and quadrature: Theory, computation, and applications

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    Quadrature rules find many applications in science and engineering. Their analysis is a classical area of applied mathematics and continues to attract considerable attention. This seminar brings together speakers with expertise in a large variety of quadrature rules. It is the aim of the seminar to provide an overview of recent developments in the analysis of quadrature rules. The computation of error estimates and novel applications also are described
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