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排序方式: 共有1792条查询结果,搜索用时 468 毫秒
91.
Tony Minoru Tamura Lopes Andre Augusto Ciré Cid Carvalho de Souza Arnaldo Vieira Moura 《Constraints》2010,15(2):151-189
Brazilian petrobras is one of the world largest oil companies. Recurrently, it faces a very difficult planning and scheduling problem: how to
operate a large pipeline network in order to adequately transport oil derivatives and biofuels from refineries to local markets.
In spite of being more economical and environmentally safer, the use of a complex pipeline network poses serious operational
difficulties related to resource allocation and temporal constraints. The current approaches known from the literature only
consider a few types of constraints and restricted topologies, hence they are far from being applicable to real instances
from petrobras. We propose a hybrid framework based on a two-phase problem decomposition strategy. A novel Constraint Programming (CP) model
plays a key role in modelling operational constraints that are usually overlooked in literature, but that are essential in
order to guarantee viable solutions. The full strategy was implemented and produced very adequate results when tested over
large real instances. 相似文献
92.
93.
94.
O.P. Malik G.S. Hope M.A.H. Sheirah 《International Journal of Electrical Power & Energy Systems》1983,5(3):159-165
The processing capability of computers makes it feasible to implement sophisticated techniques for process control. However, to minimize the software development costs, it is desirable to develop algorithms that can have a wider application. In keeping with this, an AVR and speed governor for a generating unit have been designed using the same algorithm, called the selftuning regulator. The selftuning AVR and speed governor have been implemented using a microprocessor and a minicomputer online. The feasibility of developing unified algorithms is demonstrated by means of realtime tests, in which the two controllers are used simultaneously for a generating unit physical model. 相似文献
95.
O.P. Malik G.S. Hope Ju M. Gorski V.A. Ushakov 《International Journal of Electrical Power & Energy Systems》1983,5(1):61-71
Results of experimental tests carried out with microprocessor-based voltage and speed regulators using a digital-analogue-physical model complex of a large power system at the Siberian Power Institute of the USSR Academy of Sciences are described. The physical test facility, and the test objectives and procedures are also outlined. Tests were carried out on a Soviet-built microprocessor AVR and a Canadian-built microprocessor AVR and speed governor. The work described shows that the development of speed and voltage regulators using microprocessors is a feasible and promising proposition. 相似文献
96.
故障现象:制冷正常,但制热时烧熔丝。分析与检测:该空调安装好后,试机时只试了制冷状态,制冷工作正常,却未进行制热试机。后来用户想试一下制热,拨到制热挡,熔断器一开机就跳闸,等合上闸后整机就无任何反应了。最初分析也许是巧合,检查主控板上的熔丝已经烧了,随即更换上了一块线路板,试机制冷正常,但在制热状态立刻烧熔断,判断制热存在严重短路现象。即然制冷正常,制热状态只多一个四通阀线圈用电,检查室外机的接线,原来是安装工错将三跟导线中的黄线接到了地上。 相似文献
97.
Tony Armstrong 《今日电子》2006,(10):38-39,41
就由电池供电并以微硬盘(HDD)作为主要存储介质的手持产品而言,目前有3种市场驱动因素汇聚在一起,可能导致在这些便携式产品的电池工作时间方面产生极大的突破。这类便携式产品包括便携式播放器(PMP)、MP3播放器、数码相机(DSC)、数字录像机(DVR)、智能电话和GPS系统等。 相似文献
98.
Although research has found an association between social anxiety and alcohol use in noncollege samples, results have been mixed for college samples. College students face many novel social situations in which they may drink to reduce social anxiety. In the current study, the authors tested a model of college problem drinking, incorporating social anxiety and related psychosocial variables among 228 undergraduate volunteers. According to structural equation modeling (SEM) results, social anxiety was unrelated to alcohol use and was negatively related to drinking consequences. Perceived drinking norms mediated the social anxiety-alcohol use relation and was the variable most strongly associated with problem drinking. College students appear to be unique with respect to drinking and social anxiety. Although the notion of social anxiety alone as a risk factor for problem drinking was unsupported, additional research is necessary to determine whether there is a subset of socially anxious students who have high drinking norms and are in need of intervention. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
99.
Error Analysis for Image Inpainting 总被引:1,自引:0,他引:1
Image inpainting refers to restoring a damaged image with missing information. In recent years, there have been many developments
on computational approaches to image inpainting problem [2, 4, 6, 9, 11–13, 27, 28]. While there are many effective algorithms
available, there is still a lack of theoretical understanding on under what conditions these algorithms work well. In this
paper, we take a step in this direction. We investigate an error bound for inpainting methods, by considering different image
spaces such as smooth images, piecewise constant images and a particular kind of piecewise continuous images. Numerical results
are presented to validate the theoretical error bounds.
Tony F. Chan received the B.S. degree in engineering and the M.S. degree in aerospace engineering in 1973, from the California Institute
of Technology, and the Ph.D. degree in computer science from Stanford University in 1978.
He is Professor of Mathematics and currently also Dean of the division of Physical science at University of California, Los
Angeles, where he has been a Professor since 1986. His research interests include mathematical and computational methods in
image processing, multigrid, domain decomposition algorithms, iterative methods, Krylov subspace methods, and parallel algorithms.
Sung Ha Kang received the Ph.D. degree in mathematics in 2002, from University of California, Los Angeles, and currently is Assistant
Professor of Mathematics at University of Kentucky since 2002. Her research interests include mathematical and computational
methods in image processing and computer vision. 相似文献
100.
Total Variation Wavelet Inpainting 总被引:6,自引:0,他引:6
Tony F. Chan Jianhong Shen Hao-Min Zhou 《Journal of Mathematical Imaging and Vision》2006,25(1):107-125
We consider the problem of filling in missing or damaged wavelet coefficients due to lossy image transmission or communication.
The task is closely related to classical inpainting problems, but also remarkably differs in that the inpainting regions are
in the wavelet domain. New challenges include that the resulting inpainting regions in the pixel domain are usually not geometrically
well defined, as well as that degradation is often spatially inhomogeneous. We propose two related variational models to meet
such challenges, which combine the total variation (TV) minimization technique with wavelet representations. The associated
Euler-Lagrange equations lead to nonlinear partial differential equations (PDE’s) in the wavelet domain, and proper numerical
algorithms and schemes are designed to handle their computation. The proposed models can have effective and automatic control
over geometric features of the inpainted images including sharp edges, even in the presence of substantial loss of wavelet
coefficients, including in the low frequencies. Existence and uniqueness of the optimal inpaintings are also carefully investigated.
Research supported in part by grants ONR-N00014-03-1-0888, NSF DMS-9973341, DMS-0202565 and DMS-0410062, and NIH contract
P 20 MH65166. 相似文献