Improved ESD protection by combining InGaN-GaN MQW LEDs with GaN Schottky diodes

GaN Schottky diodes were built internally inside the GaN green LEDs by using etching and redeposition techniques. By properly selecting the etching areas underneath the bonding pads, one can minimize the optical loss due to the etching process. Although the reverse current and the forward turn-on voltage were both higher for the GaN LED with a Schottky diode, it was found that the internal Schottky diode could significantly increase the electrostatic discharge threshold from 450 to 1300 V.     

Electrothermal coupling analysis of current crowding and Joule heating in flip-chip packages

Solder bumps serve as electrical paths as well as structural support in a flip-chip package assembly. Owing to the differences of feature sizes and electric resistivities between a solder bump and its adjacent traces, current densities around the regions where traces connect the solder bump increase in a significant amount. This current crowding effect along with the induced Joule heating would accelerate fatigue failure due to electromigration. In this paper we apply the three-dimensional electrothermal coupling analysis to investigate current crowding and Joule heating in a flip-chip package assembly carrying different constant electric currents under different ambient temperatures. Experiments are conducted to calibrate temperature-dependent electric resistivities of solder alloy, Al trace, and Cu trace, and to verify the numerical model by comparing calculated and measured maximum temperatures on the die surface. Through the electrothermal coupling analysis, effects of current crowding and Joule heating induced by different solder bump structures are examined and compared.     

HYDRAULICS OF COMPOUND CHANNEL WITH VEGETATED FLOODPLAINS

1. INTRODUCTIONThe Pearl River delta is often subject to typhoons and heavy rainfalls. Big waves generated by typhoons cause scouring, even collapsing and breaching of river embankments. Facts have proved that the effectiveness for wind and ship wave prot…     

气调包装中的配气技术

介绍食品气调小包装中，简易的配气装置、原理和方法。     

横电磁波传输室的三维FDTD法分析

本文运用时域有限差分（FDTD）法模拟电磁波在TEMcell（横电磁波传输室）中的传输，并对之进行了三维分析，给出了TEMcell中TEM模场的横截面分布及纵向分布；计算了TEM模与高阶模的谐振频率；分析了TEMcell的上限可用频率。此结果对横电波传输室的设计和使用具有重要意义。     

智能卡SPA＆DPA攻击

智能卡是一种可防止被入侵设计的设备，为了防止攻击者藉由边际信道泄漏信息，如功率消耗、执行时间、故障时的输出与输入行为、电磁辐射、功率尖峰情形等信息攻击智能卡，必须采取一些防备措施。本文主要介绍攻击智能卡的简易功率分析（SPA），微分功率分析（DPA）。这些技术已被广泛地使用于窃取智能卡保护数据的技术上，提供这些技术的概略性观念，使我们知道问题所在，进一步想出对策，促使我们设计出更安全的智能卡。     

如何当好一名工程总监

作者根据现阶段工程监理的现状和困难，认为作一名总监如何在如此特殊的社会环境下发挥自己的作用，要做到以下三点：即一是给业主“把脉”，了解建设意图；二是给施工方“把脉”，设定监理工作侧重点；三是合理分工，明确职责，组建“学习型”项目部。     

LNG燃料汽车的发展前景

为推动我国燃气汽车事业的发展，由国家科技部牵头于1999年成立了全国清洁汽车协调领导小组，确定把北京、上海、天津、重庆、哈尔滨、长春、西安、乌鲁木齐、成都、广州、深圳、海口等12个城市作为“空气净化工程--清洁汽车行动”试点示范城市。文章介绍了我国各地推进清洁燃料汽车的进展和现状；分析比较了LNG燃料汽车的优点：能量密度大、运输方便、安全性能好、环保效果更佳；最后预测了LNG 汽车的发展前景。     

A third secreted protein that is encoded by the enteropathogenic Escherichia coli pathogenicity island is required for transduction of signals and for attaching and effacing activities in host cells

Enteropathogenic Escherichia coli strains are able to signal host cells, cause dramatic cytoskeletal rearrangements, and adhere intimately to the cell surface in a process known as the attaching and effacing effect. A pathogenicity island of 35 kb known as the locus of enterocyte effacement (LEE) is necessary and sufficient for this effect. The LEE encodes an outer membrane adhesin called intimin, a type III secretion apparatus, and the EspA and EspB secreted proteins. The DNA sequence of the region between espA and espB revealed a new gene, espD. The product of espD was demonstrated by using a T7 expression system. We constructed a nonpolar mutation in espD and found that the mutant is incapable of the signal transduction events that lead to activation of the putative intimin receptor in host cells and that the mutant fails to induce the attaching and effacing effect. These phenotypes were restored to the mutant by complementation with a plasmid containing the cloned espD locus. We demonstrated by immunoblotting and microsequencing that the EspD protein is secreted via the type III apparatus. Thus, we describe a novel locus encoding a secreted protein that is required for attaching and effacing activity.