一种增强的ZRTP认证机制

ZRTP本身的认证机制在一些特殊的情况下无法抵抗中间人攻击。为此,基于简单密钥协商协议(SAKA)提出一种NSAKA算法,改进ZRTP的认证机制,使用RFC4474中的SIP身份认证模型来安全传输用户预共享的秘密口令。通过分析表明,该方案可以提高ZRTP抵抗中间人攻击的能力,并弥补SAKA算法原有的安全缺陷。     

一台1000m3液化石油气球罐裂纹的成因分析及裂纹修复

本文采用磁粉探伤技术对1000m3液化石油气球罐进行无损检测,并结合金相试验结果对球罐横向裂纹萌生及扩展原因进行了分析。分析表明,现场安装时组对和焊接工艺控制不严格、焊后热处理未达预期目标是造成焊缝产生大量延迟裂纹的主要原因。     

How dense are cylindrical brushes grafted from a multifunctional macroinitiator?

A series of cylindrical brushes with poly(methyl methacrylate) (PMMA) and poly(n-butyl acrylate) (PBA) side chains of different lengths was studied to understand the grafting density of brush molecules prepared by the ‘grafting from’ approach. Molecules with PMMA side chains were prepared by grafting MMA from a multifunctional macroinitiator, poly(2-(2-bromoisobutyryloxy)ethyl methacrylate). Molecules with PBA side chains were prepared with poly(2-(2-bromopropionyloxy)ethyl methacrylate) as a macroinitiator. Analysis of the detached side chains showed an incomplete initiation process resulting in longer side chains than expected for complete initiation. Limited initiation (40-80%) was also observed for short PMMA chains using a low molar mass initiator ethyl 2-bromoisobutyrate with CuCl catalyst systems. The lower initiation efficiency was confirmed via visualization of individual molecules by atomic force microscopy. The larger distance between adsorbed brush molecules was consistent with <50% initiation efficiency.     

多重循环的软件流水：比较和提高

循环并行化是并行编译的核心问题之一。许多科学计算程序的大部分执行时间花费在循环上，有效开发循环中的并行性将提高整个程序的执行效率。多重循环最为常见，因此并行化多重循环具有重要的理论和现实意义。现代处理器中硬件资源迅速增长，也使得在整个多维循环空间中开发并行性成为必要。目前大多数软件流水算法只对最内层循环，仅有少数的算法对多重循环进行软件流水，本文介绍几种多重循环的软件流水算法，比较它们之间的相似与不同之处，为编译器实现中算法的选择提供了指导。     

Evaluation of the James Initiation Criterion in the 21 mm and 50 mm PMMA Gap Test

The gap test has been used for several decades as a measure for the shock sensitivity of high explosives. Normally the axial pressure in the gap is used as the necessary initiation pressure of a high explosive for a shock to detonation transition. But it has been shown in the past that the pressure in the gap is not a suitable measure for shock sensitivity and other criteria like the James criterion in terms of critical energy fluence and critical specific kinetic energy should be used. To evaluate the James criterion in the 21 mm and 50 mm polymethylmethacrylate (PMMA) gap test numerical simulations are conducted. To validate the simulations a 21 mm water gap test is simulated and compared to experimental results, where the axial pressure calibration can be reproduced with high accuracy. With the results from the simulation of the 21 mm and 50 mm gap test it is shown that at the same maximum axial pressure the energy fluence is higher in the 50 mm gap test. This explains to some extent the higher initiation pressures observed in smaller gap tests. The James criterion is derived and it is shown that the two gap tests probe very different regions in the energy fluence vs. specific kinetic energy plane. The results can be used as a calibration for the gap tests and are intended to improve the comparability of gap test results among each other and with different initiation experiments like flyer or heavy fragment impact testing.     

Enhanced Initiation Behavior of Reactive Material Projectiles Impacting Covered Explosives

Reactive materials bring the dramatically enhanced lethality by means of the combined defeat mechanisms of impact kinetic energy and chemical energy release. This paper presents such an investigation on these reactive materials for the enhanced initiation behavior of covered explosives. First, a simple initiation process comparison between the inert metal and reactive material projectiles impacting covered explosives is described. Then high velocity ballistic impact experiments, which include both reactive material and tungsten alloy projectiles with mass matched against covered explosives, are conducted to investigate and compare the initiation behavior of covered explosives. Finally, theoretical analysis and discussions about contributions of both kinetic energy‐to‐initiation and chemical energy‐to‐initiation mechanisms to the enhanced initiation behavior of covered explosives impacted by reactive materials are presented.     

非电多段微差起爆网路在地下矿挤压爆破中的应用

利用非电多段微差爆破网路在5个钙芒硝地下矿进行了100多次挤压爆破,地表生态环境没有受到爆破震动的影响,矿石破碎质量得以改善。应用这种网路时,孔间和排间延时使用1～20段非电毫秒雷管,而线路间延时则用一定长度的导爆管来控制。文中简述了挤压爆破的机理;提出了计算排间延时间隔的经验公式;讨论了线路间延时的确定方法。此外,还介绍了这种网路的一个应用实例。     

OSGi/SIP通信中间件架构设计

根据未来家庭网络应用对3G网络的需求,提出基于开放服务网关协议/会话初化协议(OSGi/SIP)的通信中间件架构.该架构依托Android操作系统,通过套接字通信机制解决SIP网络层和OSGi应用层数据的交互问题,利用SIP的会话功能为远程用户提供交互网关应用服务.实验结果表明,该架构具有较好的通用性,适用于医疗保健监...     

对SIP协议的研究及其基本功能的一个实例

会话初始协议SIP是IETF的多媒体数据和控制体系的一部分,它是一个基于应用层的控制协议,用来邀请用户参加多媒体会议。SIP不依附于任何一种特定的会议控制协议。SIP是被设计成独立于低层的传输协议的并且可以用一些额外的功能来进行扩展。本文介绍了SIP的工作原理和一些操作并且给出了一人两个用户SIP进行初始化的简单例子。     

大规模监控系统难点问题的解决思路探讨——H3C iVS IP监控解决方案

本文重点阐述了H3C iVS IP监控解决方案的结构及组成,以及H3C iVS是如何合理应用多种成熟的IP技术,解决大规模监控系统在灵活接入、海量存储管理、业务融合及系统扩容等方面所面临的挑战的。