Strategy of improving the stability and detonation performance for energetic material by introducing the boron atoms

A novel stable energetic compound (E)‐1,2‐diamino‐1,2‐dinitrodiboron (DANB) was theoretically designed based on the structure of 1,1‐diamino‐2,2‐dinitroethene (FOX‐7). Atomization method in combination with Hess' law was used to predict the heat of formation. The detonation velocity (D) and detonation pressure (P) of DANB were approximatively estimated by using Kamlet–Jacobs equations. As a result, DANB has huge heat of formation (2013.5 kJ/mol) and specific enthalpy of combustion (?26.4 kJ/g). Furthermore, DANB possesses high crystal density (1.85 g/cm³) and heat of detonation (5476.0 cal/g), which lead to surprising detonation performance (D = 10.72 km/s, P = 51.9 GPa) that is greater than those of FOX‐7 (D = 8.63 km/s, P = 34.0 GPa) and CL‐20 (D = 9.62 km/s, P = 44.1 GPa). More importantly, DANB is very stable because its bond dissociation energy of the weakest bond (BDE = 357.8 kJ/mol) is larger than those of the most common explosives, such as FOX‐7 (BDE = 200.4 kJ/mol), CL‐20(BDE = 209.2 kJ/mol), HMX(BDE = 165.7 kJ/mol), and RDX (BDE = 161.4 kJ/mol). Therefore, our results show that DANB is a promising candidate for stable and powerful energetic material.     

High-power 880-nm diode-directly-pumped passively mode-locked Nd:YVO₄ laser at 1342 nm with a semiconductor saturable absorber mirror

A high-power 880-nm diode-directly-pumped passively mode-locked 1342 nm Nd:YVO? laser was demonstrated with a semiconductor saturable absorber mirror (SESAM). The laser mode radii in the laser crystal and on the SESAM were optimized carefully using the ABCD matrix formalism. An average output power of 2.3 W was obtained with a repetition rate of 76 MHz and a pulse width of 29.2 ps under an absorbed pump power of 12.1 W, corresponding to an optical-optical efficiency of 19.0% and a slope efficiency of 23.9%, respectively.     

光的折射定律(Snell定律)演示实验装置

基于光子动量在不同媒质分界面上沿分界面方向守恒原理,制作了光的折射定律演示装置.使用该装置可演示入射角连续变化,折射角也自动遵循折射定律相应变化.本文介绍了该演示装置的原理、构造及使用方法.     

The moire topography based on optical logic operation

The optical logic-operated moire,which is proposed on the basis of optical logicoperation,is a new method to obtain specific moire beat pattern.Its advantages lie in the ca-pability to select carrier-free,sharpened fringes with high contrast.The experimental methodand results of the application of the optical logic-operared moire in moire topography are pre-sented in this paper.     

A Novel Method for Wavelength Conversion with Dual-pump Four-wave Mixing in a Semiconductor Optical Amplifier

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　ＩｎｔｈｅＷＤＭｎｅｔｗｏｒｋ ,ｔｈｅｄｅｓｉｒａｂｌｅｆｅａｔｕｒｅｓｏｆａｎａｌｌ ｏｐｔｉｃａｌｗａｖｅｌｅｎｇｔｈｃｏｎｖｅｒｔｅｒｉｎｃｌｕｄｅｐｏｌａｒｉｚａｔｉｏｎｉｎｓｅｎｓｉｔｉｖｉｔｙ ,ｔｒａｎｓｐａｒｅｎｃｅｔｏｍｏｄｕｌａｔｉｏｎｆｏｒｍａｔａｎｄｂｉｔ ｒａｔｅ ,ｆｕｌｌｔｕｎａｂｉｌｉｔｙ ,ａｃｃｅｐｔａｂｌｅｏｕｔｐｕｔＳＮＲｏｖｅｒｔｈｅｅｎｔｉｒｅｒａｎｇｅｏｆｔｈｅｗａｖｅｌｅｎｇｔｈｓｕｓｅｄｉｎｔｈｅｎｅｔｗｏｒｋ[1] .Ｗａｖｅ…     

The Combinatorics of Laguerre,Charlier, and Hermite Polynomials

This paper describes several combinatorial models for Laguerre, Charlier, and Hermite polynomials, and uses them to prove combinatorially some classical formulas. The so-called “Italian limit formula” (from Laguerre to Hermite), the Appel identity for Hermite polynomials, and the two Sheffer identities for Laguerre and Charlier polynomials are proved. We also give bijective proofs of the three-term recurrences. These three families form the bottom triangle in R. Askey's chart classifying hypergeometric orthogonal polynomials.     

基于小波分解系数的贝叶斯人脸识别方法

本文给出了贝叶斯人脸识别方法中匹配准则的多个近似表达式及一种实用的快速计算方法,在此基础上,利用反对称双正交小波变换的微分算子功能,提出了一种利用两幅人脸图像的小波变换系数差作为模式矢量的贝叶斯人脸识别方法,并利用AR人脸图象库进行了实验,实验结果表明本文方法与基于图像灰度的类似方法相比,识别率提高8％左右,此外本文方法也提供了一条在图像压缩数据域中实现人脸识别的可能途径。     

近严格凸与最佳逼近

本文研究近严格凸与最佳逼近的关系．证明了Ｂａｎａｃｈ空间Ｘ是近严格凸的当且仅当Ｘ的每个子空间是紧－半－切比晓夫空间．     

荧光法直接测定环境中邻羟基苯甲酸和苯酚混合物的含量

本文研究了用荧光分光度法测定环境水中苯酚和邻羟基苯甲酸的含量碘在ＰＨ〉１１时直接测定邻羟基苯甲酸的含量,波长为λｅｘ／λｅｍ＝２８９／３３８ｎｍ,检出 为３．４ｎｇ／ｍＬ,线性范围０－６．０μｇ／ｍＬ。在ＰＨ＝６,波长为λｅｘ／λｅｍ＝２７０／２９７ｎｍ测得苯酚含量,检出限为４．０ｎｇ／ｍＬ,线性范围在０－０．８５μｇ／ｍＬ,回收率为９８－１０１％,,结果满意。