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81.
82.
83.
Kai Tang Ming-En Wang Lin-Lin Chen Shuo-Yan Chou Tony C. Woo Ravi Janardane 《Computer aided design》1997,29(12):825-836
A translational sweep is the translating of a polygon, called the generatrix G, around another polygon, called the directrix D, under two conditions: (1) G is always in contact with D; and (2) the interiors of G and D do not intersect. Three classes of translational sweep are studied, including the case in which both G and D are convex; the case in which G is convex, D monotone; and the case in which both are monotone. Efficient algorithms for computing the trajectory and the swept area as well as geometric and computational properties are presented for each class. A notion called the inverse generatrix, which reveals a duality between the trajectory and the swept polygon, is introduced to reduce complexity. 相似文献
84.
Novel error concealment method with adaptive prediction to the abrupt and gradual scene changes 总被引:1,自引:0,他引:1
Soo-Chang Pei Yu-Zuong Chou 《Multimedia, IEEE Transactions on》2004,6(1):158-173
In this paper, the impact of scene change on the conventional error concealment method is addressed and a novel error concealment method is proposed to improve the insufficiency of the conventional temporal error concealment algorithm due to the occurrence of scene change. Combining with the low complexity scene change detection algorithm using macroblock type information, the corrupt blocks resulting from bit errors are concealed either temporally or spatially depending on whether or not an abrupt scene change is found. In the case of gradual scene change, a novel error concealment method of interpolation and extrapolation is proposed to utilize the linear property of gradual scene change sequence, and effectively reduce the concealment error in comparison with the conventional algorithm. A great improvement of about 3 to 5 dB PSNR on average and 6 to 8 dB in some cases is obtained with very little memory and computation overhead. 相似文献
85.
Discovery of context-specific ranking functions for effective information retrieval using genetic programming 总被引:1,自引:0,他引:1
Fan W. Gordon M.D. Pathak P. 《Knowledge and Data Engineering, IEEE Transactions on》2004,16(4):523-527
The Internet and corporate intranets have brought a lot of information. People usually resort to search engines to find required information. However, these systems tend to use only one fixed ranking strategy regardless of the contexts. This poses serious performance problems when characteristics of different users, queries, and text collections are taken into account. We argue that the ranking strategy should be context specific and we propose a , new systematic method that can automatically generate ranking strategies for different contexts based on genetic programming (GP). The new method was tested on TREC data and the results are very promising. 相似文献
86.
Yen-Shin Lai Po-Sheng Chen Hsiang-Kuo Lee Chou J. 《Industry Applications, IEEE Transactions on》2004,40(6):1613-1620
The main theme of this paper is to demonstrate the applications of the newly developed common-mode voltage reduction pulsewidth-modulation (PWM) technique, which restricts the common-mode voltage to one-third of DC-link voltage, to vector-controlled induction motor drives. As compared to previous common-mode voltage reduction techniques, the presented technique can be applied to the inverter with diode front end and has no adverse effect on the linear modulation range. Therefore, vector-controlled drives using the developed technique for inverter control have a wide speed range. Moreover, the effects of the common-mode voltage reduction PWM technique on speed response for vector-controlled induction motor drives will be fully investigated in this paper. It will be demonstrated by intensive experimental results that speed performance does not deteriorate significantly within the rated speed range. 相似文献
87.
A. Norman A. Ahmed J. Chou A. Dalal K. Fortson M. Jindal C. Kurz H. Lee K. Payne R. Rando K. Sheppard E. Sublett J. Sussman I. White 《Computational Economics》2004,23(2):173-192
A consumer entering a new bookstore can face more than 250,000alternatives. The efficiency of compensatory and noncompensatory decisionrulesfor finding a preferred item depends on the efficiency of their associatedinformation operators. At best, item-by-item information operators lead tolinear computational complexity; set information operators, on the other hand,can lead to constant complexity. We perform an experiment demonstrating thatsubjects are approximately rational in selecting between sublinear and linearrules. Many markets are organized by attributes that enable consumers toemploya set-selection-by-aspect rule using set information operations. In cyberspacedecision rules are encoded as decision aids. 相似文献
88.
Influence of Conductivity of Slag on Decarburization Reaction 总被引:3,自引:0,他引:3
By altering the electrochemical properties of slag, the decarburization reaction of Fe3+-based slag withFe-C droplet was studied. The results showed that a lot of free electrons and holes exist in the slag containing transition metal oxides (such as TiO2 and Fe2O3). So electronic conduction in the slag increases. Finally, it led to the increment of the decarburization reaction rate between slag and Fe-C droplet, and mass fraction of carbon remaining indroplet decreases to a lower level. 相似文献
89.
J. Ha S. Chae K. W. Chou T. Tyliszczak P. J. M. Monteiro 《Journal of Materials Science》2012,47(2):976-989
This study investigated the effects of organic polymers (polyethylene glycol and hexadecyltrimethylammonium) on structures
of calcium silicate hydrates (C–S–H) which is the major product of Portland cement hydration. Increased surface areas and
expansion of layers were observed for all organic polymer modified C–S–H. The results from attenuated total reflectance–Fourier
transform infrared (ATR–FTIR) spectroscopic measurements also suggest lowered water contents in the layered structures for
the C–S–H samples that are modified by organic polymers. Scanning transmission X-ray microscopy (STXM) results further supports
this observation. We also observed difference in the extent of C–S–H carbonation due to the presence of organic polymers.
No calcite formed in the presence of HDTMA whereas formation of calcite was observed with C–S–H sample modified with PEG.
We suggest that the difference in the carbonation reaction is possibly due to the ease of penetration and diffusion of the
CO2. This observation suggests that CO2 reaction strongly depends on the presence of organic polymers and the types of organic polymers incorporated within the C–S–H
structure. This is the first comprehensive study using STXM to quantitatively characterize the level of heterogeneity in cementitious
materials at high spatial and spectral resolutions. The results from BET, XRD, ATR–FTIR, and STXM measurements are consistent
and suggest that C–S–H layer structures are significantly modified due to the presence of organic polymers, and that the chemical
composition and structural differences among the organic polymers determine the extent of the changes in the C–S–H nanostructures
as well as the extent of carbonation reaction. 相似文献
90.
设计了连续而又稳定循环的三效吸附式热泵单元-三效冷环。由于各吸附床的吸附循环之间具有先后连贯性,因此既避免了吸附床的过热,又消除了热泵输出端的不稳定工作状态,使得热泵系统的COP值Yong效率以及各吸附循环的效率比双效和单效系统均有显著提高。 相似文献