38毫米催泪子母弹增程设计及弹道仿真

在子母弹射程优化控制问题的研究中,射程是武器系统重要战术性能指标,增加射程可有效提高武器作战性能.在分析子母弹射程、弹丸初速及装药量三者关系的基础上,针对38毫米催泪子母弹发射器出口速度较低导致的实际射程较近(＜100米)及无法达到预期战术技术指标的问题.由于传统发射器出口初速度低,性能差.为此提出用数字仿真的方法,在MATLAB上进行弹道模型仿真,仿真出子母弹的弹道曲线.仿真结果表明,在保持药室容积不变的情况下,增加装药量,可提高子母弹初速,进而增大射程.通过计算机仿真射弹过程中的大量随机因素,相当于在计算机上打靶,所得结果具有较高的可信度和精度.以某型38毫米催泪子母弹为实例,结果表明,方法精确、简单实用,可为子母弹射程优化设计提供参考.     

基于MapXtreme的数字校园房管系统的开发

校园规模在不断地扩大,校园房屋管理规划部门对日益更新和迅速增加的建筑物房屋信息的管理与维护愈感困难,而现有的系统对空间数据与属性数据没有很好集成,更不利于图文信息的相互查询、检索和更新等。针对如上现实问题,应用MapInfo平台中的WebGIS技术,即MapXtreme技术,以及UML统一建模技术和SQL Server数据库等技术,成功地实现了数字校园房屋管理系统设计与开发,解决了房管部门面临的查询搜索更新校园建筑房屋信息时效率低下、管理与维护困难等实际问题。     

燃气轮机在线状态建模与仿真研究

关于燃气轮机在线监测优化问题,状态监测对于燃气轮机的安全运行起着至关重要的作用。为了实现对燃机状态监测和性能评估的优化,应对燃机机组热力性能诊断、各部件性能精确预测。根据单轴燃气轮机的工作特点,进行系统建模,通过牛顿迭代法确定燃机各部件的共同工作点,实现对各种运行状态的监测和评估,并针对某型燃机编制了状态监测和性能评估软件进行仿真。结果表明,运算收敛速度较快,得到的结果与型燃机运行数据趋势基本一致,满足燃气轮机在线状态监测的需要,可以投入工程应用。     

双发模式下视三维SAR成像方法研究

在合成孔径雷达(SAR)成像优化过程中,由于受到地形环境噪声的影响,使成像模糊和信息丢失,利用阵列天线SAR(LA-SAR)进行成像是一个不错的解决方法。然而传统的单发模式要求有足够多的阵元以满足空间采样率的要求,工程实现的难度较大。为解决上述问题,提出了一种采用正负斜率线性调频信号的双发模式下视三维SAR成像新方法,可以大幅减少天线阵元的数目,提高雷达平台的空间利用率,有效降低工程实现的难度。分析校正了俯仰向的距离徙动因子,给出了双发模式下回波信号的处理方法。进行仿真的结果证明了改进的三维成像方法对成像优化的有效性。     

温度对Ni—P化学镀层结合力影响的研究

用弯曲法、划痕法研究了镀后加热温度对Ni-P化学镀层结合力的影响,结果表明:镀后退火温度越高,镀层结合力越好,但温度过高时,镀层硬度将下降。用金相观察及电子探针分析,探讨了镀后退火温度影响结合力的机理。结果指出:退火时将在镀层和基体界面上发生Ni与Fe的互扩散,形成Ni-Fe合金扩散层,从而提高了结合力。为了能在保证镀层硬度的前提下提高结合力,本文提出了二次镀覆的设想,获得较好试验结果。     

High-temperature sulfidation of Fe-Nb alloys

The sulfidation behavior of Fe-Nb alloys containing up to 30 w/o Nb was studied over the range of 600–900°C in 0.01 aim. S₂ vapor. All alloys were two-phase, consisting of an Fe-rich solid solution and Fe₂Nb, and followed the parabolic rate law at all temperatures. Scales consisted of two layers-an outer layer of FeS and an inner, complex layer which contained some FeS, FeNb₂S₄ (possibly some FeNb₃S₆), NbS₂, and intermetallic particles which were either completely or only partially sulfidized. Platinum markers were located always at the interface between the two layers, which corresponded to the original metal surface. Activation energies were 18±3 kcal/mol in close agreement with the 19.8 reported for pure iron. The sulfidation rate decreased markedly with increasing Nb content of the alloys. The decrease is attributed to increasing amounts of Fe₂Nb with increasing Nb, the net effect being that the diffusion path for outward iron diffusion through the inner layer is reduced as the Nb content increases. An analysis of the structure of NbS₂ reveals that it is easily intercalated with Fe between loosely bonded layers of S-Nb-S. The S-Nb-S layers are covalently bonded which results in very low diffusivities of either S or Nb in pure NbS₂. Although intercalated Fe tends to change the Van der Waal's type bonding between layers to more ionic or covalent, Fe diffuses readily between the layers in NbS₂. Intercalation of Fe also increases the concentration of sulfur defects in NbS₂, which in turn increases the diffusivity of sulfur. Nb was observed to be immobile. Thus, it is thought that either outward iron diffusion or inward sulfur diffusion in the inner layer is the rate-controlling step, in spite of the close agreement of activation energies with that of the sulfidation of pure iron.     

Simulation of smoke flow and longitudinal ventilation in tunnel fire

1 Introduction The tunnel is one of the important facilities of railroad and highway transportation, and also a throat of railroad and highway. With the development of transportation, there are more and more tunnels. Although the tunnel fire occurs seldo…     

Site occupations and ordering behaviour of O phase in Ti2AlNb—based intermetallics

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离子氮化对镀铬层组织与性能的影响

研究了镀铬层经离子氮化后的组织和性能。分别用SEM、电子探针和X光衍射仪观察和分析了复合处理层剖面的组织、结构和成分,试验结果表明:离子氮化能使镀铬层的网状裂纹弥合,可明显提高了镀层表面硬度、结合力和耐蚀性。     

考虑客户画像和能量枢纽的配电网多目标抢修重构模型

随着大规模风电以及能量枢纽接入配电网,配电网故障后抢修重构面临新挑战,提出一种考虑客户画像和能量枢纽的配电网多目标多故障抢修重构模型。通过对配电网用电客户多因素精准画像,确定权重,建立兼顾客户画像和能量枢纽的配电网多目标抢修重构模型,提出一种改进NSGA-II算法以适应对模型求解,从而获得Pareto解集,并利用模糊最大满意度进行决策。算例仿真表明所提模型正确有效,与传统模型相比更加精细而客观。