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51.
Seong Hyuk Lee Junghee Lee Kwan-Gu Kang Joon Sik Lee 《Journal of Mechanical Science and Technology》2006,20(8):1292-1301
This article investigates numerically the carrier-phonon interactions in thin gallium arsenide (GaAs) film structures irradiated
by subpicosecond laser pulses to figure out the role of several recombination processes on the energy transport during laser
pulses and to examine the effects of laser fluences and pulses on non-equilibrium energy transfer characteristics in thin
film structures. The self-consistent hydrodynamic equations derived from the Boltzmann transport equations are established
for carriers and two different types of phonons, i.e., acoustic phonons and longitudinal optical (LO) phonons. From the results,
it is found that the two-peak structure of carrier temperatures depends mainly on the pulse durations, laser fluences, and
nonradiative recombination processes, two different phonons are in nonequilibrium state within such lagging times, and this
lagging effect can be neglected for longer pulses. Finally, at the initial stage of laser irradiation, SRH recombination rates
increases sufficiently because the abrupt increase in carrier number density no longer permits Auger recombination to be activated.
For thin GaAs film structures, it is thus seen that Auger recombination is negligible even at high temperature during laser
irradiation. 相似文献
52.
With video compression standards such as MPEG‐4, a transmission error happens in a video‐packet basis, rather than in a macroblock basis. In this context, we propose a semantic error prioritization method that determines the size of a video packet based on the importance of its contents. A video packet length is made to be short for an important area such as a facial area in order to reduce the possibility of error accumulation. To facilitate the semantic error prioritization, an efficient hardware algorithm for face tracking is proposed. The increase of hardware complexity is minimal because a motion estimation engine is efficiently re‐used for face tracking. Experimental results demonstrate that the facial area is well protected with the proposed scheme. 相似文献
53.
Kwang-Chul Noh Hyeon-Cheol Lee Dae-Young Kim Myung-Do Oh 《Electronics Packaging Manufacturing, IEEE Transactions on》2008,31(2):143-149
Practical studies on the method of contamination control for yield enhancement in the cellular phone modules production line were carried out. A contamination control method was proposed, consisting of data collection, data analysis, improvement action, verification, and implementation of control. The partition check method and the composition analysis for data collection and data analysis were respectively used in the cellular phone modules manufacturing process, and these methods were evaluated by the variation of yield loss before and after implementing the actions for improvement. In the partition check method, the critical process step was selected, and yield loss reduction through improvement actions was observed, whereas in the composition analysis, critical sources were selected, and yield loss reduction through improvement actions was investigated. From the results, it is concluded that the partition check and the composition analysis are effective solutions for contamination control in cleanroom production lines. 相似文献
54.
Hsu‐Wei Fang Hsien‐Chieh Wang Teh‐Hua Tsai Wei‐Bor Tsai Shao‐Yi Hou Hsuan‐Liang Liu Wun‐Hsing Lee Yung‐Chang Lu Chun‐Hsiung Huang 《应用聚合物科学杂志》2008,108(4):2428-2437
Wear of ultrahigh‐molecular‐weight polyethylene (UHMWPE) and wear‐particle‐induced osteolysis and bone resorption are the major factors causing the failure of total joint replacements. It is feasible to improve the lubrication and reduce the wear of artificial joints. We need further understanding of the lubrication mechanism of the synovial fluid. The objective of this study is to evaluate the lubricating ability of three major components in the synovial fluid: albumin, globulin, and phospholipids. An accelerated wear testing procedure in which UHMWPE is rubbed against a microfabricated surface with controlled asperities has been developed to evaluate the lubrication behavior. An analysis of the wear particle dimensions and wear amount of the tests has provided insights for comparing their lubrication performance. It is concluded that the presence of biomolecules at the articulating interface may reduce friction. A higher concentration of a biological lubricant leads to a decrease in the wear particle width. In addition, in combination with the wear results and mechanical analysis, the roles of individual biomolecules contributing to friction and wear at the articulating interface are discussed. These results can help us to identify the role of the biomolecules in the boundary lubrication of artificial joints, and further development of lubricating additives for artificial joints may be feasible. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
55.
Han‐Lang Wu Chen‐Chi M. Ma Chun‐Chieh Lin Yie‐Chan Chiu Chih‐Yuan Chen Chin‐Lung Chiang 《应用聚合物科学杂志》2008,107(5):3236-3243
Poly(arylene ether benzonitrile) (PAEBN) was synthesized with 2,6‐dichlorobenzonitrile and biphenol. PAEBNs with various molecular weights (MWs), 1,640,000 and 185,000 g/mol, were synthesized by control of the stoichiometry of the monomers and were blended with sulfonated poly(ether ether ketone) (SPEEK). The effects of MW on the water uptake, swelling, methanol permeability, and proton conductivity of the SPEEK/PAEBN blend membranes were investigated. The molecular mobility of the SPEEK/PAEBN blends was also examined in this study. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
56.
为了改善筛分机械的使用环境,降低筛分机械的噪声,从噪声源入手,从内因和外因两个方面分析了筛分机噪声的形成原因。论述了USL和USK系列振动筛在降低噪声方面所采取的先进技术措施。 相似文献
57.
58.
59.
Chun Lin Ma Qing Feng Wang Rufen Zhang Jikun Li 《Journal of Inorganic and Organometallic Polymers and Materials》2008,18(2):229-235
Six triorganotin(IV) complexes of the type {(R3Sn)2[C3S3(COO)2]}n (R = C6H5 1; n-Bu 2; PhCH2 4; p-F-PhCH2 5; o-F-PhCH2 6) and {(R3Sn)2[C3S3(COO)2]}n·[EtOH] (R = Me 3) have been synthesized by the reaction of bis(carboxymethyl)trithiocarbonate with triorganotin(IV) chloride
in the presence of sodium ethoxide. All complexes were characterized by elemental analysis IR, 1H, 13C and 119Sn NMR spectroscopy. Except for 4–6, all complexes were also characterized by X-ray crystallography. The X-ray date revealed
that complexes 1–3 show two-dimensional network polymeric structure in which the geometries of tin atoms are trigonal bipyramid
with the axial positions occupied by carboxylic oxygen atoms. 相似文献
60.
Learning and memory of novel spatial configurations aids behaviors such as visual search through an implicit process called contextual cuing (M. M. Chun & Y. Jiang, 1998). The present study provides rigorous tests of the implicit nature of contextual cuing. Experiment 1 used a recognition test that closely matched the learning task, confirming that memory traces of predictive spatial context were not accessible to conscious retrieval. Experiment 2 gave explicit instructions to encode visual context during learning, but learning was not improved and conscious memory remained undetectable. Experiment 3 illustrates that memory traces for spatial context may persist for at least 1 week, suggesting a long-term component of contextual cuing. These experiments indicate that the learning and memory of spatial context in the contextual cuing task are indeed implicit. The results have implications for understanding the neural substrate of spatial contextual learning, which may depend on an intact medial temporal lobe system that includes the hippocampus (M. M. Chun & E. A. Phelps, 1999). (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献