斜拉桥拉索风雨激振理论模型和机理研究

斜拉桥拉索风雨激振的机理研究是国际风工程和桥梁工程领域的著名难题。本文设计、制作了可方便调节拉索模型倾角和风向角的试验装置以及用于测压试验的带人工雨线的拉索模型,并在风洞中进行了细致的试验。试验得到了具有典型倾角的拉索在不同风向角下,拉索和水线模型上的平均风压和脉动风压系数,以及气动力系数。在此基础上,建立了拉索风雨激振新的理论模型,计算分析了节段三维拉索的风雨激振响应及其机制。     

智慧火箭数据获取技术探索与展望

随着智慧火箭概念的提出,对运载火箭数据获取技术提出新的挑战,目前,运载火箭存在测量领域受限、测量精度不高、可靠性不高、可扩展性差和可裁剪性不高等问题。结合数据获取现状和问题分析,总结出未来数据获取朝着智能化、网络化和轻质高效化方向发展的趋势。结合趋势研判给出某火箭的数据获取总体框架,并对结构健康监测、光纤传感网络、无缆化等关键技术的优缺点和应用场景进行对比分析,提出了光纤光栅传感网络、无线传感网络、磁谐振式无线传能等技术在智慧火箭数据获取上的应用展望。     

空间碎片撞击卫星影响分析及验证

近年来，空间碎片环境日益复杂严峻，对卫星在轨飞行构成严重威胁，发生碰撞风险大幅增加。针对低轨卫星遭受空间碎片撞击问题，分析了撞击产生的二次碎片云损伤机理，提出了利用遥测数据评估撞击产生的影响，分析撞击信息的流程，设计了相应地面验证实验。结果表明:碎片云引发二次损伤为空间碎片撞击卫星主要损伤形式。碎片云可导致多层隔热材料(MLI)发生破损甚至严重撕裂、外翻，同时引起供电线缆损伤、导线被击断。破损的供电电缆，通过大电流后发生断路的可能性急剧提升，对卫星危害巨大。     

索网结构非线性有限元分析中初始张力状态的快速构造方法

预应力索网结构是以柔性拉索为主要承重构件或辅助承重构件的一种结构体系,用于可展开天线等空间结构。为在有限元数值分析时准确、高效地施加张拉预应力,综合考虑索网的几何非线性、刚度矩阵奇异性、索网与支撑结构存在耦合变形等问题,利用索网式可展开天线的特性,在非线性有限元计算时忽略初位移刚度矩阵,将问题线性化,并详细介绍了以降温法模拟预应力时降温值的计算过程。此方法无需迭代,且得到的降温值在用于索网非线性计算时具有足够的精度;此方法能充分利用通用有限元计算程序,可进一步开展模态和响应等力学计算,便于在工程中实际应用。     

Reliability analysis of arresting hook engaging arresting cable for carrier-based aircraft influenced by multifactors

The carrier-based aircraft landing and arrest process is complex and nonlinear, and includes the coupling effect between the aircraft and arresting system. It has many uncertain factors, which lead to difficulty in the reliability analysis. To make the reliability analysis more accurate and effective, this paper presents some studies. Taking a certain type of carrier-based aircraft as the research object, a dynamic model of the landing and arrest cable was established, and the accuracy of the model was verified using laboratory test results. Based on the model, this paper shows how the key parameters, including the sinking velocity, pitch angle and horizontal velocity, affect the collision rebound performance of the arresting hook. After that, a limit state equation of the arresting hook system’s reliability was established. For the implicit limit state equation, a surrogate model of the reliability of the arresting hook was established using the Support Vector Machine (SVM) method, and then reliability analysis was carried out using the Monte Carlo method. Finally, it was explained in detail how the key parameters affect the reliability of the hook engaging the arresting cable, and some meaningful conclusions were obtained. This analysis method and its results can provide a reference for the top-level parameter design of carrier-based aircraft and reliability research on the arresting systems.     

A new approach for pulse amplitude measurement using Lagrange’s interpolation for radiation or particle detectors

In radiation detector signal processing, usually, the charge-sensitive preamplifier converts the small charge signal coming from the semiconductor-based detector into voltage form and then the signal is further amplified to measure the energy of the incoming radiation. The voltage pulse from a charge-sensitive preamplifier (CSPA) is amplified using a shaping amplifier which reduces the signal bandwidth. To achieve better energy resolution, precise measurement of the peak amplitude of shaping amplifier output is required. The signal processing methods are available in which the signal from the charge-sensitive preamplifier can be directly digitized using high-speed Analog to Digital Converters (ADC), and then further signal processing such as gain and shaping is carried out inside the Field Programmable Gate Arrays (FPGA). For multiple detector systems, digital signal processing methods are quite difficult to implement in Field Programmable Gate Arrays (FPGA). In this context, The development of an alternative technique is initiated that uses a charge-sensitive preamplifier, shaping amplifier, low sampling analog-to-digital converter, and FPGA, where LaGrange’s interpolation technique is implemented in FPGA to precisely measure the peak of the analog pulse. In this paper, the comparison of the proposed method with other pulse amplitude measurement techniques is discussed. Results show that the implemented technique gives similar energy resolution compared to digital pulse processing and standard peak detector-based techniques.