基于QoS的PQ_SIP协议栈设计

针对某些网络对业务和用户划分优先级的问题,该文基于现有会话初始化协议（SIP）栈设计一种支持服务质量（QoS）的PQ_SIP协议栈,并将其应用于某部人民防空应急通信指挥系统中。实践证明,改进后的协议栈能有效提高终端资源的利用率,体现用户和数据业务的不同优先级,实现对呼叫和会话有差别的控制。     

基于SIP的无线局域网络视频电话系统

未来的电信网络无论是固网还是移动网络都将整合成一个AllIP网络的架构。因此异构网络间的信息如何正确的传递变得尤为重要,SIP协议已成为其中的重要关键技术。目前在有线的因特网上,已有许多通信软件提供了语音服务,而本研究则以SIP为基础在无线局域网络上开发视频电话系统,并设计了客户端代理者接口程序与服务器系统,在无线局域网中实现了基于SIP技术的视频电话系统。     

基于PTD2112的VoIP网关的软硬件设计

以往的IP电话设备主要采用H．323协议实现，但是H．323协议实现过程较复杂，在实际使用中存在很多的问题．提出一种基于FFD2112的VoIP网关的实现方法，阐述了基于FFD2112的VoIP网关的软硬件设计过程，电话接口的性能测试结果表明，所提出的方案在因特网上运行良好．     

基于强认证技术的会话初始协议安全认证模型

针对会话初始协议（SIP）的典型安全威胁,提出了基于强认证技术的SIP安全认证模型,并分析了其安全性。该认证模型通过智能卡和数字证书的强组合实现强认证,并据此对SIP做出相应扩展,将强认证技术有机地融入到SIP协议当中,实现了会话双方的安全认证,保证了SIP消息传输的机密性、真实性、完整性和不可否认性,从而提高了SIP的安全性。     

Divergent Detonation Wave Processes in PBX Based on RDX

In order to characterize the initial phase of the divergent detonation wave in PBX, a hemispheric explosive sample was initiated by a long cylindrical charge of the same explosive. The tested PBX is composed of 85 wt% of RDX and 15 wt% of binder based on HTPB. This PBX‐RDX presents an effective density of 1.57 g/cm³, and a detonation velocity of 7.90 mm/μs.     

Environment and time dependent effects on the fatigue response of an advanced nickel based superalloy

The fatigue behaviour of the nickel based superalloy RR1000 is characterised using double edge notch specimens incorporating shot peening. Evaluations were conducted at two test temperatures, 300 °C and 650 °C, employing baseline and dwell waveforms. The effects of air and vacuum environments plus prior exposure at 650 °C were also assessed. It is demonstrated that surface oxidation does not control performance at the test conditions of interest. Rather, the modification to stabilized peak and mean stresses resulting from either thermal relaxation of peened stresses or a time dependent shake down of stress under mechanical loading governs ultimate behaviour.     

Projectile Attack of Surface Scattered Munitions Comparing Closed Form Theory with Live Trials

This paper describes research that has been undertaken to develop a low‐cost vehicle‐mounted gun system to provide for the rapid disposal of surface deployed munitions (principally mines) from up to 100 m distance. Inert high‐shock projectiles with optimized internal, external and terminal ballistic performance have been developed during this study. Work on shock wave interaction was reviewed in terms of the Rankine‐Hugoniot jump equations, and Walker and Wasley criterion has been employed using two modifications from James to predict initiation in this divergent shock application.     

熔融挤出接枝法制备粘接性LDPE

用过氧化二异丙苯(DCP)作引发剂,通过双螺杆挤出机将复合接枝单体、低密度聚乙烯(LDPE)、分散剂(ESBO)混合均匀后进行熔融挤出接枝反应,制备粘接性LDPE,并对有关影响因素及熔融接枝反应机理进行讨论。     

Shear Initiation of Al/MoO3‐Based Reactive Materials

Reactive mixtures based on nano aluminium and nano‐ or micron size molybdenum trioxide have been pressed. These energetic mixtures have been tested in the Ballistic Impact Chamber and as an energetic projectile impacting a steel plate. Al/MoO₃‐based reactive mixtures can be initiated by a controlled mechanical stimulus. The sensitivity depends on deformation velocity, pressing density, addition of fluorine containing binder and particle size. Nanometric mixtures of Al and MoO₃ have a shorter time to reaction compared to the corresponding mixtures with micron size MoO₃. The sensitivity decreases with increase in porosity. No influence of fuel/oxidizer ratio has been found in the experiments. An extensive deformation is needed before the start of reaction is observed. An analytical evaluation of shear rate cannot be applied as a detailed numerical simulation of the deformation process in PBXN‐109 shows.     

The Shock Initiation Threshold of HNS as a Function of its Density

The shock initiation threshold of hexanitrostilbene (HNS) pellets with different densities has been investigated by performing small‐scale gap tests. As the sensitivity of HNS strongly depends on the density of the pellet, the density was varied in a range that the pellet material can be expected to be insensitive by means of no initiation at pressure loads of 2.6 GPa. In the case of HNS we observed that the material became insensitive at densities larger than 1.65 g cm⁻³. Further, we found that the pressure loads can be increased from 2.6 GPa to 3.29 GPa for densities increasing from ϱ=1.65 g cm⁻³ to ϱ=1.70 g cm⁻³ (98% TMD) without detonation of the HNS pellet.