4,753 research outputs found

    Energy release mechanism of current loops in the solar atmosphere: solar flares and corona heating

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    Policy-Oriented Impact Assessment of Climatic Variations

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    IIASA organized a Task Force Meeting (held in late June 1986) to undertake a policy-oriented assessment of various climatic impacts. Among the questions addressed were: What are the main policy questions and research needs of this field? Is there a niche for IIASA to fill meaningfully over the next several years? If so, should the work be an independent entity within the current Environment Program or should it be absorbed within the framework of other projects? This report of the Task Force Meeting provides a focus not only for IIASA, but also for many other national and international bodies engaged in climate impact research. In particular, the idea of integrated regional assessments seems to have caught on, and this Research Report is likely to become a basic reference

    MHD equilibrium and stability properties of a bipolar current loop

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    Magnetic Phase Diagram of the Ferromagnetically Stacked Triangular XY Antiferromagnet: A Finite-Size Scaling Study

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    Histogram Monte-Carlo simulation results are presented for the magnetic-field -- temperature phase diagram of the XY model on a stacked triangular lattice with antiferromagnetic intraplane and ferromagnetic interplane interactions. Finite-size scaling results at the various transition boundaries are consistent with expectations based on symmetry arguments. Although a molecular-field treatment of the Hamiltonian fails to reproduce the correct structure for the phase diagram, it is demonstrated that a phenomenological Landau-type free-energy model contains all the esstential features. These results serve to complement and extend our earlier work [Phys. Rev. B {\bf 48}, 3840 (1993)].Comment: 5 pages (RevTex 3.0), 6 figures available upon request, CRPS 93-

    Recreation Demand of Consumer with Experiential Marketing in Festival

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    AbstractExperiential marketing that allows visitors to fully participate and appreciate festival activities con be coupled with strategies of market segmentation, which is of great benefit to industrial and cultural activities. In this study, we used factor analysis method to understand the perception factor of visitors participate the Sweet Taiwan Year Festival in Tainan country of Taiwan. And segmented festival market by cluster analysis based on delineated experiential perception factors. The empirical result of this study shows that experiential perception clusters and the visitor type have become the most important factors in influencing the experiential value, the relation quality and the relation outcome

    Image Reconstruction with a LaBr3-based Rotational Modulator

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    A rotational modulator (RM) gamma-ray imager is capable of obtaining significantly better angular resolution than the fundamental geometric resolution defined by the ratio of detector diameter to mask-detector separation. An RM imager consisting of a single grid of absorbing slats rotating ahead of an array of a small number of position-insensitive detectors has the advantage of fewer detector elements (i.e., detector plane pixels) than required by a coded aperture imaging system with comparable angular resolution. The RM therefore offers the possibility of a major reduction in instrument complexity, cost, and power. A novel image reconstruction technique makes it possible to deconvolve the raw images, remove sidelobes, reduce the effects of noise, and provide resolving power a factor of 6 - 8 times better than the geometric resolution. A 19-channel prototype RM developed in our laboratory at Louisiana State University features 13.8 deg full-angle field of view, 1.9 deg geometric angular resolution, and the capability of resolving sources to within 35' separation. We describe the technique, demonstrate the measured performance of the prototype instrument, and describe the prospects for applying the technique to either a high-sensitivity standoff gamma-ray imaging detector or a satellite- or balloon-borne gamma-ray astronomy telescope.Comment: submitted to Nuclear Instrument & Methods, special edition: SORMA 2010 on June 16, 201

    Phenomenological model of elastic distortions near the spin-Peierls transition in CuGeO3CuGeO_3

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    A phenomenological model of the Landau type forms the basis for a study of elastic distortions near the spin-Peierls transition TcT_c in CuGeO3CuGeO_3. The atomic displacements proposed by Hirota {\it et al.} [Phys. Rev. Lett. {\bf 73}, 736 (1994)] are accounted for by the model which includes linear coupling between CuCu and OO distortions. CuCu displacements are seen to be responsible for anomalies in the elastic properties {\it at} TcT_c, whereas incipient OO distortions give rise to temperature dependence below TcT_c. A discussion of possible critical behavior is also made.Comment: 1 figure available upon reques

    A 7/9 - Approximation Algorithm for the Maximum Traveling Salesman Problem

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    We give a 7/9 - Approximation Algorithm for the Maximum Traveling Salesman Problem.Comment: 6 figure

    A New Algorithm for Automatic History Matching

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    Parameterized complexity of DPLL search procedures

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    We study the performance of DPLL algorithms on parameterized problems. In particular, we investigate how difficult it is to decide whether small solutions exist for satisfiability and other combinatorial problems. For this purpose we develop a Prover-Delayer game which models the running time of DPLL procedures and we establish an information-theoretic method to obtain lower bounds to the running time of parameterized DPLL procedures. We illustrate this technique by showing lower bounds to the parameterized pigeonhole principle and to the ordering principle. As our main application we study the DPLL procedure for the problem of deciding whether a graph has a small clique. We show that proving the absence of a k-clique requires n steps for a non-trivial distribution of graphs close to the critical threshold. For the restricted case of tree-like Parameterized Resolution, this result answers a question asked in [11] of understanding the Resolution complexity of this family of formulas
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