激光击穿不同气体的激光推进实验研究

为了研究激光击穿气体工质的机理,通过测量冲量耦合系数,比较了激光在不同压强下击穿不同惰性单原子气体(氩气、氦气)的效果,试验结果表明:原子序数较大的无机气体原子可以电离出更多的电子,从而击穿阈值更低,激光能量转化为爆轰波能量的能量转化效率更高,冲量耦合系数就越大,同样条件下更容易击穿。推进剂气体不同,冲量耦合系数差别较大。测量摆角对结果的影响也较大。     

基于切削热-力耦合效应的表面强化技术及其工艺试验研究

经过对超高强度钢工件高速切削加工表面质量的系统研究,发现在某种特定的切削条件下,工件表面质量将会发生显著改变.该变化不仅表现为表面特征的大幅改善,如表面粗糙度可以控制在0.4μm以下,无宏观裂纹发生等,还表现为表层及次表层显微硬度的明显提高、最大残余压应力深度的大幅增加(达到0.35 mm)以及表面耐磨性能的显著增强等.研究结果表明,合理的切削工艺将极有可能成为一种能够在获得工件结构形状与精度指标的同时,对加工表面表层、次表层的组织特性与工件使用性能产生积极影响的表面强化手段.     

三轴陀螺稳定平台的惯量耦合问题研究

分析了三轴陀螺稳定平台的惯量耦合规律,给出了转动惯量耦合方程,并进行仿真计算与分析,从而为陀螺稳定平台的进一步研究工作打下了基础。     

一种抑制控制力矩陀螺框架电机共模电压的方法

控制力矩陀螺作为执行机构,是保障航天器在轨寿命和工作性能的核心部件之一。为了抑制控制力矩陀螺外框电机的共模电压,提高控制力矩陀螺的在轨寿命,本文提出了一种三相四桥臂的拓扑结构与优化的SVPWM调制算法结合的共模电压抑制方法,调制过程中避免零矢量的使用,使驱动器可以保持在平衡状态,经过仿真试验的结果对比分析,验证了这种方法可以有效的抑制系统的共模电压。     

交流电子负载校准技术研究

介绍了交流电子负载的校准方法、校准设备和校准原理等。交流电子负载是对是各种交流电源、UPS电源测试和老化试验的主要设备之一,其各项参数指标的优劣对被测设备的检测及故障分析具有重要意义。研究了交流负载的恒定电压、恒定电流、恒定电阻和恒定功率等功能的校准方法和指标,并通过实际测试、校准进行了验证,对校准结果的不确定度进行了评定,校准结果表明本文的校准方法能够满足仪器的技术要求。     

干涉配合构件的应力腐蚀开裂特性

采用恒载荷拉伸实验技术,研究了镀锌３０ＧｒＭｎＳｉＡ锡螺栓干涉配合连接ＬＹ１２－ＣＺ铝合金构件在３．５％ＮａＣａｌ＋０．５％Ｈ２Ｏ２溶液中的应力腐蚀开裂特性。结果表明,随干涉量的增加,应力腐蚀敏感性有所下降,基材与紧固件的电偶效应对应力腐蚀繁感性有重大影响。     

Effects of yaw-roll coupling ratio on lateral-directional aerodynamic characteristics

Experimental investigation of large amplitude yaw-roll coupled oscillations was conducted in a low-speed wind tunnel using an aircraft configuration model. A special test rig was designed and constructed to provide different coupled motions from low to high angles of attack.A parameter ‘‘coupling ratio" was introduced to indicate the extent of yaw-roll coupling. At each pitch angle, seven coupling ratios were designed to study the yaw-roll coupling effects on the lateraldirectional aerodynamic characteristics systematically. At high angles of attack, the damping characteristics of yawing and rolling moments drastically varied with coupling ratios. In the coupled motions with the rotation taking place about the wind axis, the lateral-directional aerodynamic moments exhibited unsteady characteristics and were different from the ‘‘quasi-steady" results of the rotary balance tests. The calculated results of the traditional aerodynamic derivative method were also compared with the experimental data. At low and very high angles of attack, the aerodynamic derivative method was applicative. However, within a wide range of angles of attack, the calculated results of aerodynamic derivative method were inconsistent with the experimental data, due to the drastic changes of damping characteristics of lateral-directional aerodynamic moments with yaw-roll coupling ratios.     

Coupled Stress-Electricity Model for Electromagnetic Emission Induced by Concrete Fracture

Electromagnetic emission induced during concrete fracturing is of great significance to health monitoring of concrete structures.A coupled stress-electricity model is established by analyzing the interaction between stress and electricity during concrete fracturing.And based on this model,the electromagnetic radiation parameters are calculated.The theoretical calculation is well coincident with experimental results.This work provides theoretical support for concrete testing system.     

用于航空高压直流电源系统的笼型异步发电机控制策略的研究

 现代电力电子技术的发展使得笼型异步发电机能够适用于航空高压直流系统中。着重对笼型异步电机与电力电子变换器结合构成的发电系统进行了研究,说明了采用直接转矩控制策略可使这种发电系统具有很好的动态特性。介绍了异步发电机直接转矩控制的原理与实现方法,并给出了仿真与实验结果。     

基于BICMOS电流控制型多路输出电源的研制

介绍一种适用于低压、宽范围供电的多路输出DC/DC变换器,在功率电路中使用无损耗箝位电路实现了变压器磁芯的复位,控制电路使用第三代BICOMS电流控制型PWM,简化了电路设计、降低了噪声敏感度,给出了多路输出电源中变压器和耦合电感的工程设计的详细过程,同时分析了多路输出耦合电感对负载交叉调节性能的影响.研制的变换器输入电压范围8V-40VDC,输出5V/3A、±15V/0.5A、 10V/0.5A.