北斗三号新信号体制共视时间比对

为促使北斗系统特别是北斗三号系统尽早加入国际原子时计算,利用中国科学院国家授时中心以及捷克无线电工程和电子学院两个守时实验室接收机产生的北斗三号新信号体制观测数据,开展基于北斗三号新信号体制共视时间比对试验。结果表明,北斗三号信号的多路径噪声影响小于北斗二号信号,且信噪比优于北斗二号信号。对比已有的研究,北斗三号新信号体制(B1C和B2a)共视时间比对的噪声相对于北斗三号卫星播发的北斗二号兼容信号体制(B1I和B3I)有较大的改善,其结果与GPS、Galileo共视比对结果相当,且在零基线共钟比对中,基于北斗三号新信号体制比对钟差的标准偏差相对于北斗二号信号提高了40%以上;利用北斗三号新信号体制共视得到的亚欧两地钟差噪声小于北斗二号信号,且比对钟差的稳定度相对于北斗二号提高了10%以上。该试验也可为北斗三号时间比对纳入国际原子时计算提供相关的研究基础。     

Reaction degree of composition B explosive with multi-layered compound structure protection subjected to detonation loading

The explosive reaction degree and protection from explosions are concerns in the military field.In this work,the reaction degree of the composition B explosive was investigated experimentally.Multi-layered compound structures were used as barriers to weaken the blast loads.A comprehensive experiment using a high-speed camera and image processing techniques,side witness plates,and bottom witness plates was presented.Using the experimental fragment velocities,fragment piercing patterns,and damage characteristics,the reaction degree of the explosive impeded by different multi-layered com-pound structures could be precisely differentiated.Reaction parameters of the explosive obstructed by compound structures were obtained by theoretical analysis and numerical simulations.Unlike the common method in which the explosive reaction degree is only distinguished based on the initial pressure amplitude transmitted into the explosive,a following shock wave reflected from the side steel casing was also considered.Different detonation growth paths in the explosive formed.Therefore,all these shock wave propagation characteristics must be considered to analyze the explosive response impeded by compound structures.     

Thermodynamics and performance of Al/CuO nanothermite with different storage time

The storage stability of energetic materials is important for its application. Here, the storage stability of Al/CuO nanothermite, which was prepared by electrospray method and stored with different storage time, was systematically researched. The activation energy of Al/CuO nanothermite was calculated by differential scanning calorimetry (DSC). The ignition temperature and the curve pressure history of Al/CuO nanothermite was measured using ignition temperature measuring device and constant-volume pressurization tests, respectively. Further, the thermites were characterized by X-ray Diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and Transmission electron microscopy (TEM). The results show that the morphology of the thermites did not change significantly. The activation energy was decreased from 254.1 kJ/mol to 181.8 kJ/mol after storage for 13 months. When stored for 0, 7 and 13 months, the peak pressures of Al/CuO nanothermite were 685.8 kPa, 626.3 kPa and 625.5 kPa, respectively. In addition to the ignition temperature, it was 775 ℃, 739 ℃ and 754 ℃, respectively. This result indicated that the ignition and combustion properties of Al/CuO nano-thermite are obviously reduced when stored for a long time, at room temperature.     

基于排队论的防空导弹群作战效能研究

结合防空导弹群防空战斗的特点,利用可列状态生灭过程的排队论方法,研究了防空导弹群作战效能,建立了数学模型,分析了导弹群防空武器系统对目标平均击毁概率的计算方法,并通过引入拦截适宜性因子对理想条件下的排队模型进行了修正,为类似问题的研究提供了一种参考。     

电晕放电辐射场若干特性分析

为了研究电晕放电辐射场若干特性,首先进行了电晕放电时电晕电流的理论分析,研究了电晕电流的波形随电压变化情况。然后在采用针-板电极物理实验模型的基础上进行了电晕放电实验研究,分析了放电针上的充电电压对脉冲电流的影响,并确定了辐射场随传播距离的变化规律以及放电重复率随电压的变化情况。实验结果发现,当针为负极性时先发生放电,但正极性下先发生火花放电;电晕放电辐射场与距离成反比关系;放电重复率随着电压的增大而增大。     

基于IP层的保密通信技术研究及实现

针对W indows2000下自带的IPSec与L inux的IPSec相互通讯比较困难的问题,对L inux IPSec、ND IS网络驱动程序以及WDM设备驱动程序进行了研究,在W indows平台下设计并实现了一个基于中间层驱动程序的IP-Sec,它能与L inux IPSec通讯。中间层驱动程序对过往的数据包进行加密或者解密操作是通过WDM设备驱动程序与上层应用程序的通讯机制,以此来实现应用层与内核的双向通讯,即应用层向内核传递密钥及其他配置信息,内核向上层应用程序提供底层的配置信息。此外,在L inux IPSec源代码的基础上增加了安全审计功能,具体测试结果表明,这个系统可以与L inux IPSec通信。     

一种用于ESD测试的PLC单轴运动控制台研究

研制了一种以可编程控制器 (PLC) 作为控制单元的单轴控制台。这种单轴控制台有效控制了静电放电(ESD) 模拟器空气放电电极的运动状态, 为ESD测试实验提供了一种新的手段, 并与手持放电方式进行了实验比较。     

指挥自动化系统可生存性研究

可生存性是指当一个系统在受到攻击、出现错误或发生紧急事件时仍然能够完成其任务的一种能力.指挥自动化系统是现代战争中部队战斗力的倍增器.在信息化战争条件下,传统的安全策略将不能保证指挥自动化系统的生存能力.通过介绍可生存性思想,分析指挥自动化系统及子系统的特点和存在的问题,提出了利用可生存性设计指挥自动化系统的基本原则.     

国外保障性试验与评价的做法与启示

保障性试验与评价是实现装备战备完好性目标、降低装备寿命周期费用和研制风险的重要而有效的决策手段.分别介绍了美、法、德、日等国家在保障性试验与评价方面的组织、结构、管理和实际做法,并得出几点启示,为我国开展保障性试验与评价提供了借鉴和参考.     

论我国的法学教育现状及法律人才的培养

随着改革开放,经济发展,我国法学教育在实践中存在的弊端已日益凸显,对法学教育的改革刻不容缓。本文从分析我国法学教育的现状入手,提出对法学教育改革方向和新世纪法律人才培养的几点建议。