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791.
民用航空事故可能导致部分人群的心理危机,我国可在“突发公共事件应急指挥中心”下设灾难心理服务中心——主管国家灾后心理救援的全局工作,并相应成立省、市一级的心理服务机构,整合其他资源,共同组成我国多层级的、有效的心理救援框架. 相似文献
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溶液法制备PVDF薄膜电活性相方法 总被引:4,自引:4,他引:0
为了制备具有电活性相的聚偏氟乙烯(PVDF)薄膜,采用了简单易操作的溶液涂膜方法,并研究了不同前驱体溶液浓度、搅拌时间以及热压工艺对PVDF不同电活性相的晶型结构形成的影响,利用X射线衍射仪、傅里叶变换红外光谱仪(FTIR)对PVDF薄膜的晶型结构进行分析.结果表明:前驱体溶液浓度7%~10%,搅拌时间2~3h都有利于β相的形成,利用红外光谱,可以计算β相的含量,在前驱体溶液浓度7%,搅拌时间2h时得到最大的β相含量81.3%;热压对PVDF薄膜的晶型结构有很大的影响,经过热压处理的PVDF薄膜中γ相转变成更加致密的β相. 相似文献
795.
针对脉冲星导航要求X射线探测器具有高能量分辨率和高时间分辨率的需求,研究基于石墨烯电场效应来实现X射线探测的可行性。通过蒙特卡罗方法模拟不同能量X射线和不同厚度探测器基底的相互作用过程,得到不同厚度探测器对X射线的探测效率。利用有限元方法分析X射线在探测器内电离产生载流子的输运过程,验证了X射线入射对石墨烯电学特性的影响。理论分析计算探测器的时间分辨率和能量分辨率等指标参数,结果表明:基于石墨烯电场效应的X射线探测器具有较高的能量分辨率和时间分辨率,是一种潜力巨大的X射线探测方式,可满足未来脉冲星导航的工程应用。 相似文献
796.
突然启动流动问题在气动弹性、扑翼飞行和机动飞行中有重要应用价值。鉴于此,对突然启动流动问题涉及的流动与升力演化机制和理论分析方法进行统一介绍并指出目前的理论空白。比较性地介绍了升力随时间变化的原因、预测升力演化的理论方法和主要变化规律。从中发现,不可压缩和可压缩突然启动问题存在各自独立的研究方法与结论,因此进行统一介绍与分析对建立二者之间的关联有指导意义。同时指出,大迎角可压缩突然启动问题尚无理论分析方法和研究结果。作为一项补充研究,采用数值计算发现一个之前尚未报道的现象,即升力系数首先从较低值快速增加至一个峰值,接着快速下降,趋于定常值。该文综述介绍的方法可用于分析突然启动问题升力演化规律。 相似文献
797.
Xingzhi Hu Xiaoqian Chen Yong Zhao Wen Yao 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
The separation systems are crucial for the launch of satellites. With respect to the existing design issues of satellite separation systems, an optimization design approach based on Multi-Island Genetic Algorithm is proposed, and a hierarchical optimization of system mass and separation angular velocity is designed. Multi-Island Genetic Algorithm is studied for the problem and the optimization parameters are discussed. Dynamic analysis of ADAMS used to validate the designs is integrated with iSIGHT. Then the optimization method is employed for a typical problem using the helical compression spring mechanism, and the corresponding objective functions are derived. It turns out that the mass of compression spring catapult is decreased by 30.7% after optimization and the angular velocity can be minimized considering spring stiffness errors. Moreover, ground tests and on-orbit flight indicate that the error of separation speed is controlled within 1% and the angular velocity is reduced by nearly 90%, which proves the design result and the optimization approach. 相似文献
798.
Peng Chen Yibin Yao Jiajun Chen Wanqiang Yao Xuejun Zhu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
On April 20, 2013, an earthquake of M7.0 occurred in Lushan, Sichuan province, China. This paper investigates the coseismic ionospheric anomalies using GPS (Global Positioning System) data from 23 reference stations in Sichuan province that are a part of the Crustal Movement Observation Network of China (CMONOC). The recorded results show that a clear ionospheric anomaly occurred within 15 min after the earthquake near the epicenter, and the occurrence time of the anomalies recorded by various stations is related to the distance from the epicenter. The maximum anomaly is 0.25 TECu, with a 2 min duration and the distance of the recording station to the epicenter is 83 km. Acoustic waves generated by the crustal vertical movement during the earthquake propagate up to the height of the ionosphere lead to the ionospheric anomaly, and the propagation speed of the acoustic wave is calculated as 0.72 ± 0.04 km/s based on the propagation time and propagation distance, consistent with the average speed of sound waves within a 0–450 km atmospheric height. 相似文献
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800.
Directing to the strong position coupling problem of electro-hydraulic load simulator (EHLS), this article presents an adap-tive nonlinear optimal compensation control strategy based on two estimated nonlinear parameters, viz. the flow gain coeffi-cient of servo valve and total factors of flow-pressure coefficient. Taking trace error of torque control system to zero as control object, this article designs the adaptive nonlinear optimal compensation control strategy, which regards torque control output of closed-loop controller converging to zero as the control target, to optimize torque tracking performance. Electro-hydraulic load simulator is a typical case of the torque system which is strongly coupled with a hydraulic positioning system. This article firstly builds and analyzes the mathematical models of hydraulic torque and positioning system, then designs an adaptive nonlinear optimal compensation controller, proves the validity of parameters estimation, and shows the comparison data among three control structures with various typical operating conditions, including proportion-integral-derivative (PID) controller only, the velocity synchronizing controller plus PID controller and the proposed adaptive nonlinear optimal compensation controller plus PID controller. Experimental results show that systems’ nonlinear parameters are estimated exactly using the proposed method, and the trace accuracy of the torque system is greatly enhanced by adaptive nonlinear optimal compensation control, and the torque servo system capability against sudden disturbance can be greatly improved. 相似文献