Analysis of junction temperatures in high-power GaN-based LEDs

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...     

Photoluminescence of face-centered-cubic structure silicon nanoparticles deposited by pulsed laser ablation

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...     

有机硅耐烧蚀材料的研究进展

对有机硅耐烧蚀材料发展现状,影响性能的因素及应用前景作了较全面的综述。     

A new similarity computing method based on concept similarity in Chinese text processing

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.     

交流电机直接转矩控制系统的MATLAB仿真研究

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。     

一年级

在一年级教学的基本内容是什么？一年级和预科之间有什么不同？一年级的课程包括对整个建筑化的介绍,项目的介绍,和怎样去解决一个项目的问题。通过工作室和普通的项目,我们试图提供给学生怎样工作的方法。预科是针对缺少交流和基本技能的人。通过训练,我们教你怎样享受和建造,你需要我们的支持来完成一个项目。在预科有更多的连续的支持体系。     

桁架球填充交织网管复合结构吸能特性研究

采用Maxon Cinema 4D R21建立三维模型,利用3D打印技术打印出桁架球填充交织网管复合结构。对3D打印的不锈钢桁架球、铝合金薄壁管以及桁架球填充交织网管复合结构进行单向轴向压缩试验,得出试验曲线,计算它们的吸能指标,研究桁架球填充交织网管复合结构和其他两者的吸能特性有何不同。结果表明,复合结构可直接影响结构冲击变形程度和吸能能力,三种结构中,复合结构所能承受的载荷最高,桁架球所能承受的载荷最弱。经过试验研究,薄壁管的缓冲吸能特性介于铝合金薄壁管和桁架球之间。     

Investigation on mechanism of polymer filling in high-aspect-ratio trenches for through-silicon-via (TSV) application

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.     

RV减速器针摆传动啮合特性分析

在分析RV减速器的传动原理和结构特点的基础上,从系统角度出发,考虑RV减速器两级传动系统耦合变形、摆线轮轮辐结构以及轴承刚度,建立了RV减速器啮合特性分析模型。对RV减速器针摆传动啮合特性进行了仿真分析,具体讨论了摆线轮轮缘厚度、修形量以及载荷大小对啮合特性的影响规律。同时根据所建立的分析模型对RV减速器的扭转刚度进行了分析。最后通过对RV减速器进行了针齿壳齿根压应力实验测试以及扭转刚度实验测试,验证了仿真分析的正确性。