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ChemInform Abstract: Magnetic Properties and Magnetocaloric Effect in Selected MM′X‐type (M, M′: 3d or 4d Metal, X: As, P, Ge) and Mn1‐xTxAs‐type (T: 3d Metal) Intermetallics

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ChemInform 2011年第35期42卷

作者： Ryszard Zach Wieslaw Chajec Janusz Tobola Daniel Fruchart El Kebir Hlil Mohamed Balli Pierre Wolfers Inst. Phys. Fac. Phys. Math. Appl. Comput. Sci. Krakow Univ. Technol. PL‐30‐084 Krakow Pol.

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关键词： inorganic chemistry, review dielectric properties, magnetic properties transition metals phosphorus group

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Adaptive Synchronization Between Hyperchaotic Lorenz System and Chen System

Adaptive Synchronization Between Hyperchaotic Lorenz System ...

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International Conference on comput.tional Intelligence and Security

作者： Francis Austin Chen Xu Jian-wen Feng Wei-qiang Zhang Dept. of Appl. Math. Hong Kong Polytech. Univ. Kowloon China Inst. of Intell. Comput. Sci. Shenzhen Univ. Shenzhen China Hong Kong Polytechnic University Kowloon HK

This paper introduces the chaos synchronization between two different hyperchaotic systems with fully unknown parameters, i. e. the synchronization between hyperchaotic Lorenz system and hyperchaotic Chen system. Based on the Lyapunov stability theory, an adaptive control law is derived for the case when the parameters of the drive and response systems to be synchronized are fully uncertain. Finally, numerical simulation results are presented to show the effectiveness of the techniques.

关键词： Chaotic communication Adaptive control Control systems comput.tional intelligence Lyapunov method Numerical simulation Security Competitive intelligence math.matics Optical arrays

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Web Services Interfaces and Open Standards Integration into the European UNICORE 6 Grid Middleware

Web Services Interfaces and Open Standards Integration into ...

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International Workshop on Enterprise Distributed Object comput.ng, EDOCW

作者： M. Riedel B. Schuller D. Mallmann R. Menday A. Streit B. Tweddell M. Shahbaz Memon A. Shiraz Memon B. Demuth T. Lippert D. Snelling S. van den Berghe V. Li M. Drescher A. Geiger G. Ohme A. Vanni C. Cacciari S. Lanzarini P. Malfetti K. Benedyczak P. Bala R. Ratering A. Lukichev Central Institute for Applied Mathematics John von Neumann Institute of Computing Forschungszentrum Julich Julich Germany John von Neumann Inst. for Comput. Forschungszentrum Julich Central Inst. for Appl. Math. Julich Fujitsu Laboratories Limited Hayes UK Solutions for Research T-Systems Corporation Wessling Germany High Performance Computing Department CINECA Bologna Italy Faculty of Mathematics and Computer Science Torun Nicolaus Copernicus University Torun Poland Software and Solutions Group Intel Corporation Bruhl Germany

The UNICORE grid system provides a seamless, secure and intuitive access to distributed grid resources. In recent years, UNICORE 5 is used as a well-tested grid middleware system in production grids (e.g. DEISA, D-Grid) and at many supercomput.r centers world-wide. Beyond this production usage, UNICORE serves as a solid basis in many European and International research projects and business scenarios from T-Systems, Philips Research, Intel, Fujitsu and others. To foster ongoing developments in multiple projects, UNICORE is open source under BSD license at SourceForge. More recently, the new Web services-based UNICORE 6 has become available that is based on open standards such as the Web services addressing (WS-A) and the Web services resource framework (WS-RF) and thus conforms to the open grid services architecture (OGSA) of the open grid forum (OGF). In this paper we present the evolution from production UNICORE 5 to the open standards-based UNICORE 6 and its various Web services-based interfaces. It describes the interface integration of emerging open standards such as OGSA-BES and OGSA-RUS and thus provides an overview of UNICORE 6.

关键词： Web services Middleware Service oriented architecture Space technology math.matics Grid comput.ng High performance comput.ng Supercomput.rs Production facilities Paramagnetic resonance

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Tangent linear and second‐order models from the Born and Rytov approximations

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The Journal of the Acoustical Society of America 2006年第5_SUPPLEMENT期119卷 3248-3248页

作者： Emmanuel Skarsoulis George Piperakis George Makrakis Inst. of Appl. & Comput. Math. FORTH P.O. Box 1385 711 10 Heraklion Greece Univ. of Crete Crete Greece

Adjoint and higher‐order methods for the solution of inverse problems in underwater acoustics rely on tangent linear and higher‐order models of the forward propagation problem, with respect to the underlying parameters of interest. The use of Born and Rytov approximations is examined for the representation of perturbations of the Green’s function and perturbations of the phase, respectively, caused by range‐dependent variations of the sound‐speed distribution about a range‐independent background environment. Using the normal‐mode representation for the background Green’s function and appl.ing the stationary‐phase approach in combination with analytic evaluation at singular points, closed‐form expressions are derived for the first‐ and second‐order perturbations of the Green’s function, generalizing previous perturbation results derived under the assumption of range independence. The resulting expressions for the phase show the second‐order character of the phase (and the associated travel times) in the case of range‐dependent, zero‐mean sound‐speed perturbations.

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Reconstructing the seafloor properties from acoustic reflection data

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The Journal of the Acoustical Society of America 2005年第4B_SUPPLEMENT期89卷 1883-1883页

作者： John S. Papadakis Michael I. Taraoudakis Panagiotis J. Papadakis Foundation for Res. and Technol.‐Hellas Inst. of Appl. and Comput. Math. P.O. Box 1527 711 10 Iraklion Crete Greece

The determination of the structure of the seafloor using measurements of the acoustic reflected power is an important inverse hydroacoustic problem with many appl.cations in ocean geophysics. A realistic description of the seafloor includes many sedimentary layers over a harder substrate. Assuming that a rough estimation of the thicknesses of the various layers is available (by suitable subbottom profiling) the important thing is to recover the properties of the various layers, that is, the density, the sound velocity, and the attenuation coefficient. A simple scheme for the reconstruction of the seabottom is presented based on the assumption that reliable reflection coefficient measurements from a broadband acoustic source are available. The scheme is based on a systematic variation of the geoacoustic parameters of a background bottom model, so as the calculated reflection coefficient converges to the measured data. It is shown that data from various frequencies are necessary in order to obtain satisfactory results. [Work supported by EEC/MAST program.]

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Sensitivity kernels of finite‐frequency travel times in ocean acoustic tomography

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The Journal of the Acoustical Society of America 2004年第5_SUPPLEMENT期115卷 2617-2617页

作者： Emmanuel K. Skarsoulis Bruce D. Cornuelle Inst. of Appl. and Comput. Math. FORTH 711 10 Heraklion Crete Greece Scripps Inst. of Oceanogr. La Jolla CA 92093

Wave theoretic modeling is appl.ed to obtain travel‐time sensitivity kernels representing the amount by which travel times are affected by localized sound‐speed variations anywhere in the medium. In the ray approximation travel times are sensitive to medium changes only along the corresponding eigenrays. In the wave‐theoretic approach the perturbations of peak arrival times are expressed in terms of pressure perturbations, which are further related with the underlying sound‐speed perturbations using the first Born approximation. In this way, an integral representation of travel‐time perturbations is obtained in terms of sound‐speed perturbations; the associated kernel represents the spatial sensitivity of travel times to sound‐speed perturbations. The appl.cation of the travel‐time sensitivity kernel to an ocean acoustic waveguide gives a picture close to the ray‐theoretic one in the high‐frequency case but significantly differs at lower frequencies. Low‐frequency travel times are sensitive to sound‐speed changes in areas surrounding the eigenrays, but not on the eigenrays themselves, where the sensitivity is zero. Further, there are areas of positive sensitivity, where, e.g., a sound‐speed increase results in a counter‐intuitive increase of arrival times. These findings are confirmed by independent forward calculations.

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An axially twice acceleration low impedance HPM source 12

An axially twice acceleration low impedance HPM source

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12th International Conference on High-Power Particle Beams, BEAMS 1998

作者： Ding, Wu Inst. of Appl. Phys. and Comput. Math. P.O.Box 8009 Beijing China

ISBN: (纸本)0780342879

M.J. Arman presented a new low impedance HPM source-Radial Acceletron (1996), it has the following new characteristics: (1) There are very high harmonic currents in the device because it combines the oscillator and the diode into one;(2) The impedance of the diode is very low due to being coaxial, thus allowing larger input and output powers. We try to make two improvements for the device: (1) Add a accelerating section after the diode/ oscillator, make the bunched beam to be accelerated again, then extract the radiation emitted by the bunched and postaccelerated beam in the extraction cavity. Therefore one can not only raise the power and conversion efficiency of the beam, but also select output frequency of the waves. While in the Radial Acceletron, the conversion efficiency is not high enough, and the output frequency can not be tuned;(2) Change the radial acceleration to axial acceleration. In the configuration of radial outward twice acceleration, radius of the cavity should be very large, and the field and beam in it are divergence. In the configuration of radial inward acceleration, the power capacity is very small;While the new configuration of axially twice acceleration does not have these problems. The coaxial axially twice acceletron needs no magnetic guide field like the Super-Reltron. But its modulation cavity is TTO rather than SCO, and compared to SCO, it is not easy to breakdown due to its larger power capacity and the bunching of the beam is much better because of the combining of the oscillator with the diode. © 1998 Beam Organizing Committee.

关键词： Diodes

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Fast normal‐mode approximation of tomographic arrival patterns

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The Journal of the Acoustical Society of America 1996年第4_SUPPLEMENT期100卷 2614-2614页

作者： E. K. Skarsoulis Inst. of Appl. and Comput. Math. F.O.R.T.H. 71110 Heraklion Crete Greece

The wave‐theoretic calculation of arrival patterns for the needs of ocean acoustic tomography is comput.tionally expensive due to the large number of comput.tion frequencies necessary for properly synthesizing a broadband signal in the time domain. A scheme for approximate fast normal‐mode calculations of broadband acoustic signals in the time domain is proposed, based on a second‐order Taylor expansion of eigenvalues and eigenfunctions with respect to frequency. For the case of a Gaussian impulse source, a closed‐form expression is obtained for the pressure in the time domain. Using perturbation theory, analytical expressions are derived for the first and second frequency derivatives of eigenvalues and eigenfunctions. The proposed approximation significantly accelerates arrival‐pattern calculations, since the eigenvalues, eigenfunctions, and their derivatives need to be calculated at a single frequency, the central frequency of the tomographic source. Furthermore, it offers a satisfactory degree of accuracy for the lower‐ and intermediate‐order modes. This is due to the fact that essential wave‐theoretic mechanisms such as dispersion and frequency dependence of mode amplitudes are contained in the representation up to a sufficient order. Numerical results demonstrate the efficiency of the method. [Work partially supported by EU/MAST.]

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Second‐order perturbations of peak‐arrival times due to sound‐speed disturbances

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The Journal of the Acoustical Society of America 1996年第4_SUPPLEMENT期100卷 2605-2605页

作者： G. A. Athanassoulis E. K. Skarsoulis Dept. of Naval Architecture and Marine Eng. Natl. Tech. Univ. of Athens 15710 Zografos Athens Greece Inst. of Appl. and Comput. Math. Crete Greece

Ocean acoustic tomography has been commonly used in a linear framework, by assuming small perturbations of the ocean environment about a given background state. However, in the case of large sound‐speed variations (e.g., seasonal changes) nonlinear dependencies of arrival times on the sound speed may become significant; such a case occurred in the THETIS‐2 tomographic experiment conducted in 1994 in the western Mediterranean basin. Second‐order arrival‐time perturbations are studied here on a wave‐theoretic basis, using the recently introduced notion of peak arrivals [G. A. Athanassoulis and E. K. Skarsoulis, J. Acoust. Soc. Am.97, 3575–3588 (1995); Skarsoulis et al., J. Acoust. Soc. Am. 100 (August 1996)]. A second‐order perturbation formula relating arrival‐time with sound‐speed perturbations is derived, containing background arrival times and also functional derivatives of the background field with respect to the sound speed. For the case of a range‐independent environment the perturbation formula is further elaborated by exploiting normal‐mode theory. Its performance is demonstrated using simulations motivated from the THETIS‐2 environment. [Work partially supported by EU/MAST.]

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HOMOCLINIC TANGLES - CLASSIFICATION AND appl.CATIONS

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NONLINEARITY 1994年第2期7卷 441-473页

作者： ROMKEDAR, V Dept. of Appl. Math. & Comput. Sci. Weizmann Inst. of Sci. Rehovot Israel

Here we develop the Topological Approximation Method (TAM) which gives a new description of the mixing and transport processes in chaotic two-dimensional time-periodic Hamiltonian flows. It is based upon the structure of the homoclinic tangle, and supplies a detailed solution to a transport problem for this class of systems, the characteristics of which are typical to chaotic, yet not ergodic dynamical systems. These characteristics suggest some new criteria for quantifying transport and mixing-hence chaos-in such systems. The results depend on several parameters, which are found by perturbation analysis in the near integrable case, and numerically otherwise. The strength of the method is demonstrated on a simple model. We construct a bifurcation diagram describing the changes in the homoclinic tangle as the physical parameters are varied. From this diagram we find special regions in the parameter space in which we approximate the escape rates from the vicinity of the homoclinic tangle, finding non-trivial self-similar solutions as the forcing magnitude tends to zero. We compare the theoretical predictions with brute force calculations of the escape rates, and obtain satisfactory agreement.

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