水滴在撞击不同厚度水膜条件下产生的二次液滴特性

采用高速相机对水滴撞击水膜的飞溅过程进行了详细测量,分析了水滴撞击水膜的飞溅临界值、二次液滴的直径分布和二次液滴的速率等飞溅特性。结果表明,在实验参数范围内,当韦伯数增大时发生飞溅现象。此外,可以使用量纲为一参数K 来描述飞溅临界值,K=We·Oh^-0.4。当K值大于2 100时发生飞溅现象,二次液滴的量纲为一直径和二次液滴的量纲为一速率随着K值的增大而增大。水膜量纲为一厚度对二次液滴直径分布的影响不明显,但由冠状水花产生的二次液滴的平均量纲为一速率随水膜量纲为一厚度的增加而减小。     

入侵检测系统规则的挖掘

针对基于网络的入侵检测系统Snort,提出了一种新颖的规则挖掘方法.这种方法希望帮助Snort入侵检测系统,自动从检测的攻击数据中生成误用检测规则,实现自动检测最新攻击和异常攻击的能力.为了达到这样的功能,设计了一个规则挖掘模块,它能够应用数据挖掘技术从收集的检测攻击包中提出新的攻击规则,并且转化到Snort系统的检测...     

防误操作检修闸刀程序软件的开发与应用

杜绝误操作事故历来是电力公司的目标和宗旨,随着城乡电网的发展,变电所出线增多,检修闸刀的工作量增大,一但发生误操作事故,将造成极大的社会、经济影响.基于目前国内采用的机械防误装置、程序锁、电气防误装置的原理,想要实现“防止误操作检修中闸刀”的强制闭锁的可能性几乎为零.为此,笔者所在单位成立QC小组,研发出防误操作检修闸...     

Vertical and Smooth, etching of InP by Cl2／CH4／Ar Inductively Coupled Plasma at Room Temperature

We study the room-temperature dry, etching of InP by inductively coupled plasma (ICP) using C12/CH4/Ar mixtures. Etches were characterized in terms of anisotropy and surface roughness by scanning electron microscopy and atomic force microscopy, respectively. It is found that the flow ratio between C12 and Ctt4, ICP power, rf chuck power, and table temperature can greatly influence the, etching results. By adjusting, etching parameters,vertical sidewall and smooth surface can be obtained simultaneously, together with a moderate, etch rate and a good select ratio. The root-mean-square surface roughness is measured to be as low as 0.27nm. To the best of our knowledge, this is the best result for InP to date. The, etch rate is 855nm/min, and the selectivity ratio overSi02 is estimated to be higher than 15:1. The stoichiometry of the, etched surface has also been investigated by Auger electron spectroscopy. The, etched surface is found to manifest a slight P deficiency, and the ratio between P and In reaches the stoichiometric value within about 0.75nm depth into the surface.     

Deep InP Gratings for Opto-Electronic Devices Etched by C12/CH4/Ar Inductively Coupled Plasma

Deep InP gratings are etched by C12/CH4/Ar inductively coupled plasma （ICP） at room temperature. A comparison is made between SiNz mask patterns formed by wet and dry etching. SF6 reactive ion etching is adopted for smooth and vertical sidewall. The etching conditions of C12/CH4/Ar ICP are optimized for high anisotropy, and a 1.7-μm-deep InP grating with an aspect ratio of 10：1 is demonstrated. The technique is then used for the fabrication of 1.55-μm laterally coupled distributed feedback A1GMnAs-InP laser.     

230Acβ延发裂变的观测

搜索了230Ac β延发裂变. 由60MeV/u18O离子照射232Th,通过多核子转移反应产生230Ra. 经放射化学分离和薄的230Raβ- 230 Ac源的制备,获得了108个230Ac原子. 该源对云母裂变径迹探测器曝光. 借助于所测的γ能谱和两个裂变事件,鉴别了β延发裂变核230Ac,得到了它的β延发裂变几率为(1.19±0.85)×10-8.     

GaN基三维结构生长与器件应用

目前,c面氮化镓(GaN)基发光二极管的制备技术已经十分成熟并取得了商业化成功,但仍面临极化电场导致的大电流密度下效率下降(Droop效应)和黄绿光波段效率低的问题。为消除极化电场的影响,人们开始关注半极性和非极性面GaN。其中,基于传统极性面衬底通过三维结构生长来获得半极性和非极性GaN的方法,由于其低成本和生长的灵活性,受到了广泛研究。本文首先总结了三种GaN三维结构的制备方法并分析其生长机理。接着,在此基础上介绍了不同晶面InGaN量子阱的外延生长和发光特性。最后,列举了GaN基三维结构在半极性面LED、颜色可调LED和无荧光粉白光发光二极管方面的应用。     

面向高速网络连接记录管理的高效哈希表

针对高速网络环境下连接记录管理的性能需求,提出了一种改进的高效哈希表PRH-MTF(伪随机哈希-移至最前).首先在定义输入关键字即连接标识符的基础上,通过选择适当的运算符,设计了高效鲁棒的哈希函数PRH.为有效解决哈希冲突,根据网络数据流局部性特点,应用MTF启发法,改进了传统的链式冲突解决方法.以分组火车模型作为数据包到达模式,分析了PRH-MTF哈希表的算法复杂度,推导出了平均查找长度.最后通过实际高速网络数据流和模拟攻击的方式,对PRH-MTF哈希表进行了实验评估.实验结果表明,PRH-MTF哈希表在查找性能和抗攻击能力等方面均优于传统的简单排序哈希表.     

Study on the saturation characteristics of high-speed uni-traveling-carrier photodiodes based on field screening analysis

A back-illuminated mesa-structure InGaAs/InP charge-compensated uni-traveling-carrier(UTC) photodiode(PD) is fabricated,and its saturation characteristics are investigated.The responsivity of the 40-μmdiameter PD is as high as 0.83 A/W,and the direct current(DC) saturation current is up to 275 mA.The 1-dB compression point at the 3-dB cutoff frequency of 9 GHz is measured to be 100 mA,corresponding to an output radio frequency(RF) power of up to 20.1 dBm.According to the calculated electric field distributions in the depleted region under both DC and alternating current(AC) conditions,the saturation of the UTC-PD is caused by complete field screening at high optical injection levels.     

含五元杂环的聚酰亚胺的合成与性能研究

以多聚磷酸为溶剂,4-氨基苯甲酸与硫代氨基脲反应制得一种含噻二唑环的二胺单体4-(5-对氨基苯基)-1,3,4-噻二唑苯胺(2); 2与均苯四酸二酐反应合成了含五元杂环的聚酰亚胺(3),其结构和性能经¹H NMR, FT-IR和TGA表征,并研究了3的溶解性能。结果表明：3的热稳定性较好,T_5%为402 ℃。 3在二甲基亚砜、DMF和N-甲基吡咯烷酮等溶剂中溶解性较好。