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9th International Workshop on Plasma Edge Theory in Fusion Devices

作者： Ohno, N Budaev, VP Furuta, K Miyoshi, H Takamura, S Nagoya Univ Ctr Integrated Res Sci & Engn Nagoya Aichi 4648603 Japan RRC Kurchatov Inst Nucl Fus Inst Moscow 123182 Russia Nagoya Univ Grad Sch Engn Dept Energy Engn & Sci Nagoya Aichi 4648603 Japan

We have investigated the velocity distribution of the intermittent bursty fluctuations in the ion saturation currents observed in the linear divertor plasma simulator, NAGDIS-II. The intermittent bursty signals were analyzed by the wavelet transform with complex Morlet mother wavelet. Analyzing a lot of bursts in the ion saturation currents based on the wavelet cross-correlation gives the velocity distribution function. It is positively skewed at the peripheral region of the plasma column, which means the intermittent bursts mainly propagate toward the wail. The averaged velocity depends on the neutral pressure associated with the transition between the attached and detached plasmas. (C) 2004 WILEY-VCH Verlag GmbH & Co. KG A. Weinheim

关键词： blobs wavelet analysis velocity distribution

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Blob transport in the Tokamak scrape-off-layer

Blob transport in the Tokamak scrape-off-layer

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9th International Workshop on Plasma Edge Theory in Fusion Devices

作者： D'Ippolito, DA Myra, JR Krasheninnikov, SI Yu, GQ Pigarov, AY Lodestar Res Corp Boulder CO USA Univ Calif San Diego La Jolla CA 92093 USA

Recent experimental evidence suggests the importance of fast radial plasma transport in the scrape-off-layer (SOL) of tokamaks. The outward transport appears to be convective rather than diffusive, extends into the far SOL, and can produce significant recycling from the main-chamber walls, partially bypassing the divertor. A plausible theoretical mechanism to explain this phenomenon is the radial transport of "blobs" of locally dense plasma created by turbulent processes. A related process is the inward transport of "holes" of reduced density plasma, which provides a mechanism for rapid inward transport of impurities. The blob model is also consistent with the spatial and temporal intermittency and the non-Gaussian statistics observed in the SOL plasma. This paper reviews the present status of blob theory, including analytic models and simulations, and discusses the preliminary comparisons of the blob model with experimental data. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

关键词： Tokamak transport SOL convection blobs

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基于数据库的文档管理系统及其在企业中的应用

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计算机应用研究 2004年第6期21卷 183-186页

作者：傅佳芳赵保华中国科学技术大学计算机科学系

讨论了基于数据库的文档管理系统的解决方案及其实现的关键技术 ,特别是通过ADO中的Stream对象对数据库中的文档资料进行读写。

关键词：数据库 blobs ADO Recordset对象 Stream对象

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Beyond blobs in percolation cluster structure: The distribution of 3-blocks at the percolation threshold

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Physical Review E 2002年第5期65卷 056126-056126页

作者： Gerald Paul H. Eugene Stanley Center for Polymer Studies and Department of Physics Boston University Boston Massachusetts 02215

The incipient infinite cluster appearing at the bond percolation threshold can be decomposed into singly connected “links” and multiply connected “blobs.” Here we decompose blobs into objects known in graph theory as 3-blocks. A 3-block is a graph that cannot be separated into disconnected subgraphs by cutting the graph at two or fewer vertices. Clusters, blobs, and 3-blocks are special cases of k-blocks with k=1, 2, and 3, respectively. We study bond percolation clusters at the percolation threshold on two-dimensional (2D) square lattices and three-dimensional cubic lattices and, using Monte Carlo simulations, determine the distribution of the sizes of the 3-blocks into which the blobs are decomposed. We find that the 3-blocks have fractal dimension d3=1.2±0.1 in 2D and 1.15±0.1 in 3D. These fractal dimensions are significantly smaller than the fractal dimensions of the blobs, making possible more efficient calculation of percolation properties. Additionally, the closeness of the estimated values for d3 in 2D and 3D is consistent with the possibility that d3 is dimension independent. Generalizing the concept of the backbone, we introduce the concept of a “k−bone,” which is the set of all points in a percolation system connected to k disjoint terminal points (or sets of disjoint terminal points) by k disjoint paths. We argue that the fractal dimension of a k-bone is equal to the fractal dimension of k-blocks, allowing us to discuss the relation between the fractal dimension of k-blocks and recent work on path crossing probabilities.

关键词： .backbone fractal dimensions disjoint blobs decomposed percolation threshold subgraphs graph theory k-bone terminal points dimension of blocks

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Scaling and finite-size effects for the critical backbone

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FRACTALS-COMPLEX GEOMETRY PATTERNS AND SCALING IN NATURE AND SOCIETY 2003年第Feb2003_sup期11卷 19-27页

作者： Barthelemy, M Buldyrev, SV Havlin, S Stanley, HE Boston Univ Ctr Polymer Studies Boston MA 02215 USA Bar Ilan Univ Minerva Ctr IL-52900 Ramat Gan Israel Bar Ilan Univ Dept Phys IL-52900 Ramat Gan Israel

In a first part, we study the backbone connecting two given sites of a two-dimensional lattice separated by an arbitrary distance r in a system of size L. We find a scaling form for the average backbone mass and we also propose a scaling form for the probability distribution P(M-B) of backbone mass for a given r. For r approximate to L, P (M-B) is peaked around L-,(dB) whereas for r much less than L, P(M-B) decreases as a power law, M-B(-tauB), with tau(B) similar or equal to 1.20 +/- 0.03. The exponents psi and tau(B) satisfy the relation psi = d(B) (tau(B) - 1), and psi is the codimension of the backbone, psi = d - d(B). In a second part, we study the multifractal spectrum of the current in the two-dimensional random resistor network at the percolation threshold. Our numerical results suggest that in the infinite system limit, the probability distribution behaves for small i as P(i) similar to 1/i where i is the current. As a consequence, the moments of i of order q less than or equal to q, = 0 diverge with system size, and all sets of bonds with current values below the most probable one have the fractal dimension of the backbone. Hence we hypothesize that the backbone can be described in terms of only (i) blobs of fractal dimension d(B) and (ii) high current carrying bonds of fractal dimension going from d(red) to d(B), where d(red) is the fractal dimension of the red bonds carrying the maximal current.

关键词： .threshold probability distribution Power law system size multifractal blobs bonds scaling form backbone connecting average backbone peaked SCALING AND FINITE-SIZE CRITICAL BACKBONE LdB resistor network fractal dimension dB

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Development of cytochrome oxidase blobs in visual cortex of normal and visually deprived cats

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CEREBRAL CORTEX 2001年第2期11卷 122-135页

作者： Murphy, KM Duffy, KR Jones, DG Mitchell, DE McMaster Univ Dept Psychol Hamilton ON L8S 4K1 Canada McMaster Univ Dept Comp & Software Hamilton ON L8S 4K1 Canada Dalhousie Univ Dept Psychol Halifax NS B3H 4J1 Canada

Cytochrome oxidase (CO) blobs are central to our understanding of the columnar organization and parallel pathways in primate and cat visual cortex. In primates, development of blobs and their relationship with other columnar features of the visual cortex begins pre-natally, before visual experience. In kittens, the supragranular layers differentiate post-natally, after eye opening, raising the possibility that visual experience may influence the development of blobs in cat V1. We have examined the development of blobs in unfolded and flattened sections through the visual cortex of normally reared, dark reared, monocularly deprived and binocularly deprived kittens. blobs were found in superficial layers of V1 of normally reared kittens as early as 2 weeks of age, although at this age the overall GO staining in V1 was lighter than in V2. By 6 weeks of age the blobs were adult-like. A patchy pattern of CO staining was also found in V2 of young kittens but not in adults. Visual experience was not necessary for expression of the blobs and monocularly deprived kittens had well developed blobs, indicating that strong Y cell drive is not necessary for the development of blobs in cat V1. CO blobs appear in kitten V1 very early in post-natal development and their expression is independent of visual experience, suggesting that they may be an intrinsic feature of V1 organization.

关键词： .Oxidase Cytochrome deprived cats blobs

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Visualization of hemiknot DNA structure with an atomic force microscope

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NUCLEIC ACIDS RESEARCH 2002年第22期30卷 4902-4909页

作者： Lyubchenko, YL Shlyakhtenko, LS Binus, M Gaillard, C Strauss, F Arizona State Univ Dept Microbiol Tempe AZ 85287 USA Arizona State Univ Dept Biol Tempe AZ 85287 USA Inst Jacques Monod F-75251 Paris France

The hemiknot, a novel type of DNA structure in which a loop is stabilized by threading one end of the duplex through another, has been studied in this paper. The hemiknot was obtained by reassociation of a DNA fragment with (CA/TG)(n) inserts of different lengths. Slow and fast migrating products were purified by gel electrophoresis and imaged by atomic force microscopy (AFM) using the aminopropylsilatrane-mica technique for sample preparation. Slow migrating product was characterized by the formation of small blobs for the short insert (60 bp) and clear loops and other morphologies for the long insert (188 bp). These structural features were found in almost 100% of the molecules of the slow migrating sample and were not present in the control sample. Measurements showed that the location of the blobs coincided with the positions of the inserts. The sample with the 188 bp insert in the 573 bp fragment had large structural irregularities. The majority of the molecules (77%) had asymmetrically located loops. The location of the loop in the molecules correlated well with the position of the insert in the fragment. The measured sizes of the loops were in agreement with the insert size. Altogether, these data support the hypothesis for hemiknot formation suggested earlier. In addition to looped structures, other morphologies of the hemiknot were identified in AFM images. Possible models for hemiknot formation and structure are discussed.

关键词： .insert sizes morphologies bp fragment atomic force lengths AFM DNA fragment CA/TG irregularities blobs hemiknot formation

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Adsorption of PEO in highly confining porous glass

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MACROMOLECULES 2001年第23期34卷 8315-8320页

作者： Grüll, H Shaulitch, R Yerushalmi-Rozen, R Ben Gurion Univ Negev Reimund Stadler Minerva Ctr Mesoscale Macromol En IL-84105 Beer Sheva Israel Ben Gurion Univ Negev Dept Chem Engn IL-84105 Beer Sheva Israel

Adsorption of poly(ethylene oxide) within porous glass, from aqueous solutions, was investigated as a function of the polymer molecular weight, pore diameter, concentration, and time, using differential refractometry. The kinetics of the process was found to depend on the ratio of pore diameter to the correlation length in the polymer solutions. The adsorbed amount exhibited a dependence on pore diameter for the longer molecular weights, with an unexpected observation of a higher adsorption in smaller pores. This observation is explained by the interplay between geometry-dependent enthalpic gain due to adsorption and entropic loss due to confinement.

关键词： .aqueous solutions length scale correlation length confinement molecular weights blobs Adsorption of PEO Porous Glass adsorbed amount enthalpic due to adsorption entropic loss pore diameter porous media

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Three-dimensional semantic object tracking in video sequences

Three-dimensional semantic object tracking in video sequence...

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2nd Conference on Internet Imaging

作者： Gao, J Kosaka, A Purdue Univ Sch Elect & Comp Engn Robot Vis Lab W Lafayette IN 47907 USA

ISBN: (纸本)0819439894

One of the difficulties in semantic object tracking is to trace the object precisely as time going on. In this paper, a system for 3D semantic object motion tracking is proposed. Different from other approaches which have used regular shapes as tracked region, our system starts with a specially designed Color Image Segmentation Editor (CISE) to devise shapes that more accurately describe the region of interest (ROI) to be tracked. CISE is an integration of edge and region detection, which is based on edge-linking, split-and-merge and the energy minimization for active contour detection. An ROI is further segmented into single motion blobs by considering the constancy of the motion parameters in each blob. The tracking of each blob is based on an extended Kalman filter derived from linearisation of a constraint equation satisfied by the pinhole model of a camera. The Kalman filter allows the tracker to project the uncertainties associated with the blob feature points into the next frame. Feature points extraction is done by similarity test based on optimized semantic search region. Extracted feature points serially update motion parameters. Experimental results show the different stages of the system.

关键词： tracking video motion 3D segmentation Kalman filtering uncertainty region blobs

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Investigation of smooth basis functions and an approximated projection algorithm for faster tomography

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INTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY 2000年第6期11卷 347-354页

作者： Rydesäter, P Gustavsson, B Mid Sweden Univ S-83125 Ostersund Sweden Natl Inst Polar Res Tokyo 1738515 Japan

To decrease the calculation time of iterative tomographic reconstruction, this study proposes and investigates the uses of the "dot-projection" algorithm, which uses smooth basis functions for data representation. Basis functions give an approximation to the basis functions of blobs, which provide a more accurate reconstruction at the same resolution than for traditional "ray-driven" projection algorithms with voxels. This study evaluates the calculation time decrease and obtained errors from the algorithm for reconstruction, as well as its response to spatial frequencies. Finally, we compare the dot-projection for several basis functions and the ray-driven projection with respect to accuracy. (C) 2001 John Wiley & Sons, Inc.

关键词： tomography blobs fast projection smooth basis function

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