Analysis on Output Power for Multi-direction Piezoelectric Vibration Energy Harvester

To predict the performance of multi-direction piezoelectric vibration energy harvester,an equation for calculating its output power is obtained based on elastic mechanics theory and piezoelectricity theory.Experiments are performed to verify theoretical analysis.When the excitation direction is along Y direction,a maximal output power about 0.139 mW can be harvested at a resistive load of 65kΩ and an excitation frequency of 136 Hz.Theoretical analysis agrees well with experimental results.Furthermore,the performance of multi-direction vibration energy harvester is experimentally tested.The results show that the multi-direction vibration energy harvester can harvest perfect energy as the excitation direction changes in XY plane,YZ plane,XZ plane and body diagonal plane of the harvester.     

基于子阵级非周期的有限扫描阵列研究

对基于子阵级非周期的有限扫描阵列进行研究,采用数值仿真和遗传算法对基于不同子阵规模的非周期阵列进行优化设计,分析4?4和2?2两种子阵规模对接收多波束应用中伴随波束方向图的影响,研究表明子阵规模过大会引起伴随波束方向图的旁瓣抬升,通过减小子阵规模可以避免该问题,论证了设计的基于2?2子阵的非周期八角阵可应用于有限视场扫描相控阵中。     

Orbit determination and prediction of GEO satellite of BeiDou during repositioning maneuver

In order to establish a continuous GEO satellite orbit during repositioning maneuvers, a suitable maneuver force model has been established associated with an optimal orbit determination method and strategy. A continuous increasing acceleration is established by constructing a constant force that is equivalent to the pulse force, with the mass of the satellite decreasing throughout maneuver. This acceleration can be added to other accelerations, such as solar radiation, to obtain the continuous acceleration of the satellite. The orbit determination method and strategy are illuminated, with subsequent assessment of the orbit being determined and predicted accordingly. The orbit of the GEO satellite during repositioning maneuver can be determined and predicted by using C-Band pseudo-range observations of the BeiDou GEO satellite with COSPAR ID 2010-001A in 2011 and 2012. The results indicate that observations before maneuver do affect orbit determination and prediction, and should therefore be selected appropriately. A more precise orbit and prediction can be obtained compared to common short arc methods when observations starting 1 day prior the maneuver and 2 h after the maneuver are adopted in POD (Precise Orbit Determination). The achieved URE (User Range Error) under non-consideration of satellite clock errors is better than 2 m within the first 2 h after maneuver, and less than 3 m for further 2 h of orbit prediction.     

Electron density inversed by plasma lines induced by suprathermal electron in the ionospheric modification experiment

Incoherent scatter radar (ISR) is the most powerful ground-based measurement facility to study the ionosphere. The plasma lines are not routinely detected by the incoherent scatter radar due to the low intensity, which falls below the measured spectral noise level of the incoherent scatter radar. The plasma lines are occasionally enhanced by suprathermal electrons through the Landau damping process and detectable to the incoherent scatter radar. In this study, by using the European Incoherent Scatter Association (EISCAT) UHF incoherent scatter radar, the experiment observation presents that the enhanced plasma lines were observed. These plasma lines were considered as manifest of the suprathermal electrons generated by the high-frequency heating wave during the ionospheric modification. The electron density profile is also obtained from the enhanced plasma lines. This study can be a promising technique for obtaining the accurate electron density during ionospheric modification experiment.     

月球表层采样样品智能确认方法

表层采样是月球采样探测的重要方式，样品智能确认有助于提升工作效率与复杂问题处理能力。结合月球表层采样铲挖工作过程，分析了铲挖过程中臂载相机图像的特点，模仿有人参与识别过程，提出了层次解耦的月球样品智能识别流程，利用深度学习方法构建了一类深度卷积识别网络，完整地描述了图像、特征、标记在网络中的正反传递关系，并在月球表层采样地面试验中进行了验证，结果表明该方法对不同光照、不同背景、不同过程、不同形态的样品，具有较好的泛化识别能力，误识别率优于8.1%，平均单幅识别时间约0.7 s。     

Electrochemical micromachining of micro-dimple arrays on cylindrical inner surfaces using a dry-film photoresist

The application of surface textures has been employed to improve the tribological performance of various mechanical components. Various techniques have been used for the application of surface textures such as micro-dimple arrays, but the fabrication of such arrays on cylindrical inner surfaces remains a challenge. In this study, a dry-film photoresist is used as a mask during through-mask electrochemical micromachining to successfully prepare micro-dimple arrays with dimples 94 lm in diameter and 22.7 lm deep on cylindrical inner surfaces, with a machining time of 9 s and an applied voltage of 8 V. The versatility of this method is demonstrated, as are its potential low cost and high efficiency. It is also shown that for a fixed dimple depth, a smaller dimple diameter can be obtained using a combination of lower current density and longer machining time in a passivating sodium nitrate electrolyte.     

海洋大气环境下微动开关触点回跳时间增大故障的试验复现与分析

结合某型微动开关触点回跳时间增大导致某系统故障问题,设计了由干湿交替酸性盐雾试验和湿热试验组成的海洋大气环境效应加速模拟试验剖面,选取与外场故障件型号一致的微动开关为研究对象,通过实验室加速模拟试验,成功复现了外场故障现象,并结合试验结果对腐蚀性环境、电烧蚀等因素对触点回跳时间增大的影响机制进行了分析。     

飞机锁类机构性能退化可靠性分析方法综述

随着航空航天装备的快速发展,对飞行器装备的可靠性要求逐渐提高,飞机锁类机构的可靠性对飞机起降的安全至关重要。以飞机舱门锁机构为研究对象,首先通过文献调研了大量舱门锁机构并分析了锁机构的特点和失效模式,阐述了锁机构的工作原理。其次综述了锁机构失效机理建模、机构渐变损伤的研究现状以及目前存在的问题,分析了国内外有关锁机构可靠性的研究现状;并针对多连杆机构可靠性分析和锁机构可靠性分析进行了分类梳理。最后对锁机构的可靠性分析研究思路进行总结,并对目前复杂锁机构的可靠性分析存在的问题及其研究趋势进行了展望。     

超燃冲压发动机燃烧室出口温度场分布CARS测量

针对超燃冲压发动机研究中对燃烧室出口温度场的测量需求以及暂冲式超燃冲压发动机燃烧台架试验中的应用难点,开发了适用于瞬态燃烧场温度测量的单脉冲相干反斯托克斯拉曼反射（CARS）系统及CARS光谱计算和温度反演软件CARSCF。采用USED相位匹配方式来降低湍流影响,结合多尺度小波分析方法来实现CARS光谱降噪处理,提高信噪比。在暂冲式脉冲燃烧风洞上开展了来流马赫数2.6条件下超燃冲压发动机燃烧室出口温度测量试验,获取了超声速来流（冷态）建立、H₂点火加热空气、建立超声速燃烧流场直至试验结束过程中的燃烧室出口温度,以及煤油/空气燃烧时燃烧室出口温度场分布。结果显示,超声速冷流时温度处于低温（约205K）状态,随着H₂点火加热来流空气,来流温度上升至853K;随着煤油/Air点火,温度急剧上升,稳定燃烧状态下燃烧流场温度为1970K±144K。燃烧室出口截面温度场分布测量结果显示,高温区位于燃烧室出口截面上侧区域,而燃烧室出口截面上中间区域的温度低于上下两侧。燃烧室出口温度分布CARS测量结果与火焰自发光成像结果一致,表明单脉冲CARS技术用于瞬态燃烧流场温度测量的可行性。