排序方式: 共有17条查询结果,搜索用时 15 毫秒
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JIANG YuXuan LI Zheng SUN YongJian YU TongJun CHEN ZhiZhong ZHANG GuoYi ZHANG GuangChen & FENG ShiWei State Key Laboratory of Artificial Microstructure Mesoscopic Physics School of Physics Peking University Beijing China School of Electronic Information & Control Engineering Beijing University of Technology Beijing 《中国科学:信息科学(英文版)》2010,(2)
We presented the analysis of the incomplete conduction in bonding medium in high power GaN-based light-emitting diode (LED) packages. A numerical study was carried out with parametric model to understand the junction temperature variation due to bonding medium defects. Transient thermal measurement was performed to evaluate LED’s junction temperature. Thermal resistance from chip to lead frame was 20 K/W in our sample LED. It was suggested that only 60% of the surface area of the bonding medium was involved... 相似文献
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A new similarity computing method based on concept similarity in Chinese text processing 总被引:2,自引:0,他引:2
The paper proposes a new text similarity computing method based on concept similarity in Chinese text processing. The new method converts text to words vector space model at first, and then splits words into a set of concepts. Through computing the inner products between concepts, it obtains the similarity between words. The new method computes the similarity of text based on the similarity of words at last. The contributions of the paper include: 1) propose a new computing formula between words; 2) propose a new text similarity computing method based on words similarity; 3) successfully use the method in the application of similarity computing of WEB news; and 4) prove the validity of the method through extensive experiments. 相似文献
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YingTao Ding YangYang Yan QianWen Chen ShiWei Wang Xiu Chen YueYang Chen 《中国科学:技术科学(英文版)》2014,57(8):1616-1625
Vacuum-assisted spin-coating is an effective polymer filling technology for sidewall insulating of through-silicon-via (TSV). This paper investigated the flow mechanism of the vacuum-assisted polymer filling process based on experiments and numerical simulation, and studied the effect of vacuum pressure, viscosity of polymer and aspect-ratio of trench on the filling performance. A 2D axisymmetric model, consisting of polymer partially filled into the trench and void at the bottom of trench, was developed for the computational fluid dynamics (CFD) simulation. The simulation results indicate that the vacuum-assisted polymer filling process goes through four stages, including bubble formation, bubble burst, air elimination and polymer re-filling. Moreover, the simulation results suggest that the pressure significantly affects the bubble formation and the polymer re-filling procedure, and the polymer viscosity and the trench aspect-ratio influence the duration of air elimination. 相似文献
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ZHU ShiWei DU Jun WANG Lei & TU HaiLing Advanced Electronic Materials Institute General Research Institute for Nonferrous Metals Beijing China 《中国科学:信息科学(英文版)》2010,(4)
Face-centered-cubic(fcc) structure silicon nanoparticles(Si-nps) are synthesized by using nanosecond pulse excimer laser ablation of Si target in Ar ambient.The nonequilibrium environment caused by the plume confined in argon ambient gas is responsible for the formation of fcc Si-nps.Photoluminescence(PL),transmission electron microscopy,and X-ray photoelectron spectroscopy are used to characterize these Si-nps.Broad PL spectrum is obtained with a double-peak at 403 and 503 nm by an exciting laser of 325 nm... 相似文献
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Maintaining discovered frequent itemsets: Cases for changeable database and support 总被引:1,自引:1,他引:0 下载免费PDF全文
Mining frequent itemsets from large databases has played an essential role in many data mining tasks. It is also important to maintain the discovered frequent itemsets for these data mining tasks when the database is updated. All algorithms proposed so far for the maintenance of discovered frequent itemsets are only performed with a fixed minimum support,which is the same as that used to obtain the discovered frequent itemsets. That is, users cannot change the minimum support even if the new results are unsatisfactory to the users. In this paper two new complementary algorithms, FMP (First Maintaining Process) and RMP (Repeated Maintaining Process), are proposed to maintain discovered frequent itemsets in the case that new transaction data are added to a transaction database. Both algorithms allow users to change the minimum support for the maintenance processes. FMP is used for the first maintaining process, and when the result derived from the FMP is unsatisfactory, RMP will be performed repeatedly until satisfactory results are obtained. The proposed algorithms re-use the previous results to cut down the cost of maintenance. Extensive experiments have been conducted to assess the performance of the algorithms. The experimental results show that the proposed algorithms are very resultful compared with the previous mining and maintenance algorithms for maintenance of discovered frequent itemsets. 相似文献
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交流电机直接转矩控制系统的MATLAB仿真研究 总被引:4,自引:0,他引:4
本文介绍一种基于磁链偏差,转矩偏差和磁链位置来选择直接转矩控制电压矢量开关表,通过对磁链和转矩进行优化设计,提高了直接转矩控制系统的控制性能。应用MATLAB软件对其进行仿真和实验表明:DTC控制具有更好的稳定性,较强的鲁棒性和抑制扰动的能力。 相似文献
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介绍了机载导弹弹射发射装置的插头对接机构的原理,针对其分离过程建立了机构的动力学方程,并利用ADAMS软件对插头对接机构的分离过程进行了仿真分析,确定了机构中保持插头位置的弹簧力设计值和机构的插拔力,为整个机构的详细设计提供了力学依据. 相似文献
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Antimicrobial peptides from edible insects may serve as a potentially significant group of food preservatives. In the present work, the mode of action of a novel antimicrobial peptide MDpep9 from Chinese traditional edible housefly larvae was investigated. MDpep9 was shown to bind to bacterial DNA from the results of gel retardation and fluorescence quenching experiments. Further investigations confirmed that MDpep9 could bind with the phosphate group of DNA and intercalate into the base pairs in a helix of DNA or locate in hydrophobic environment of DNA. The previous and present results demonstrated that MDpep9 has dual mechanisms of bactericidal activity: disrupting bacterial cell membranes and binding to bacterial genomic DNA to inhibit cellular functions, ultimately leading to cell death. The results of DNA-binding mode may be contributive in designing new and promising antimicrobial peptides for food preservatives. 相似文献