低温热水分户计量采暖系统共用立管水力平衡分析

本文分析了重力作用压头对低温热水计量采暖系统共用立管形式的影响,通过运用基尔霍夫定律分析了下分异程式双管系统和下分同程式双管系统的水力平衡状况,得出了下分异程式双管系统更适用于低温热水采暖系统的结论,并确定了立管经济比摩阻的范围和下分异程式双管可以负担的楼层数。     

拉伸速率对NEPE推进剂力学性能的影响

运用单向拉伸手段,研究了不同拉伸速率(0.5～500 mm/min)、测试温度(25～70℃)对NEPE推进剂最大抗拉强度σm和最大伸长率εm的影响。试验结果发现,NEPE推进剂σm和εm均与拉伸速率v呈幂律函数关系,建立了相关性较好的幂函数方程σm=k(T)va和εm=f(T)vb。利用该方程,对极慢拉伸速率下NEPE推进剂σm和εm进行了预示,计算结果可为固体火箭发动机设计及推进剂贮存性能研究提供技术支持。     

双基地天基雷达功率孔径积分析

功率孔径积是制约天基雷达系统性能的一项重要因素.从接收功率的角度给出双基地天基雷达搜索方程的详细理论推导,并通过与单基地天基雷达搜索方程的比较得出一个重要的结论--双基地天基雷达的功率孔径积在面积覆盖率和目标散射系数固定条件下,只与接收距离有关而与发射距离无关.进一步证明了地球同步卫星-飞艇双基地天基雷达系统需要更低的...     

电机变频控制实现换热器节能的应用研究

结合寒冷地区气候特点与通信机房温控的现状,针对50%浓度乙二醇溶液为工质的换热器,试验研究了自然冷源利用率与换热器自身变频节能的关系。结合乙二醇冷剂的特性,通过建立功率与频率关系模型、温差与功率和频率关系模型,实现了换热器循环泵和风机的变频控制策略。结果表明:在室内外温差、换热功率与循环泵、风机频率同时满足的条件下,以功率模型作为参数进行换热器自身的变频节能是可行的。通过对哈尔滨地区的气候数据与散热房控温试验分析,证明了乙二醇换热器的变频节能效果。     

壳体内腔大深度T型刀加工方案分析

对于外形、内腔结构复杂,零件体积大,材料去除率高等特点的壳体,锻件加工要求所编制的数控程序异常复杂,数据庞大,手工编程难以编制程序。采用UGCAM作为编程手段,利用3维实体辅助编程技术解决此类问题。     

Subsidence rate monitoring of Aghajari oil field based on Differential SAR Interferometry

Land subsidence, due to natural or anthropogenic processes, causes significant costs in both economic and structural aspects. That part of subsidence observed most is the result of human activities, which relates to underground exploitation. Since the gradual surface deformation is a consequence of hydrocarbon reservoirs extraction, the process of displacement monitoring is amongst the petroleum industry priorities. Nowadays, Differential SAR Interferometry, in which satellite images are utilized for elevation change detection and analysis – in a millimetre scale, has proved to be a more real-time and cost-effective technology in contrast to the traditional surveying method. In this study, surface displacements in Aghajari oil field, i.e. one of the most industrious Iranian hydrocarbon sites, are being examined using radar observations. As in a number of interferograms, the production wells inspection reveals that surface deformation signals develop likely due to extraction in a period of several months. In other words, different subsidence or uplift rates and deformation styles occur locally depending on the geological conditions and excavation rates in place.     

机载单站只测向定位最优机动研究

概述了机载单站只测向定位最优机动求解算法，研究了基于最大方位角变化率准则下的观测机机动轨迹，得到理论上的最优定位机动，并结合实际运用，分析出两种近似最优的机动：“一”形（直线形）机动和S形机动，通过仿真，验证了这2种机动方式在一定条件下可以等效于最优机动，具有良好的定位效果。     

飞机电气系统参数测试标准实施中问题分析

结合本标准宣贯、研讨会上所提供的信息,分析了飞机电气系统参数测试标准在实际应用中存在的一些问题,并对瞬态电压和频率调制率等重点问题进行了详细的讨论和分析.     

Optimum parameter matching obtained by experiments for coring drilling into lunar simulant

This paper performs a series of ground experiments (on the Earth) to obtain optimum parameter matching for a future core drill on the Moon. Three common stages, I, II, III, are recognized with respect to the cut per revolution (CPR), which is defined as the ratio between the feeding speed and the rotating speed. The optimum matching between the feeding speed and the rotating speed for drills locates at the boundary position between Stage II and Stage III, where the coring rate saturates and the weight on the bit and the driving torque are still low. Further data analysis of the ground experiments reveals that the optimum matching signifies a proportional relation between the maximum conveying rate (MCR) by the groove of the auger and its rotating speed. The kinetic analysis in an ideal condition without gravity, the friction from the auger groove and the pressure at the bit confirm a similar proportion. The correlation between the proportions needs further study to determine whether the optimum matching obtained on the ground can be directly applied to future drills on the Moon.     

嵌金属丝推进剂燃烧起始阶段增速特性研究

考虑了使用嵌金属丝装药的发动机工作过程中的多种因素,建立了金属丝与药柱、燃气间相互作用的控制方程组,并对方程组进行了数值求解,得到了嵌金属丝推进剂在燃烧起始阶段,增速比随时间的详细变化过程。结果表明,金属丝的热扩散率、熔点、直径和黑度以各自不同的方式影响金属丝的增速效果,熔点相对较低的金属丝可能会在内弹道曲线的初始阶段形成一个轻微的压强峰,固有燃速较低、着火温度较低的推进剂对嵌入金属丝较为敏感。文中数值方法计算量小,结果可靠,适于工程应用。