Feasibility analysis of solar thermal propulsion system with thermal energy storage

Possessing relatively high specific impulse and moderate thrust levels, solar thermal propulsion (STP) is a promising candidate in spacecraft propulsion system. However, the traditional solar thermal propulsion system suffers from thrust failure in the shadow area, which seriously affects its applicability. In this paper, we investigate feasibility of regenerative solar thermal propulsion system (RSTP) incorporating thermal energy storage, which can effectively overcome unmatched synchronous working time and illumination time. A numerical model for RSTP considering the whole energy transfer process from light concentrating, heat storage, to thrust generation is built, which is verified by experiment measurements with relative errors less than 15 %. The result shows that the maximum time to complete heat storage is about 4000 s, which is within the illumination time for low Earth orbit. In the solar eclipse region, the thrust (F_t) and the specific impulse (I_sp) of the system increase with the propellant flow rate, which can reach about 2 N and 690 s, respectively. What’s more, the system can operate for around 100 s continuously at the maximum thrust in the shadow area. This work provides alternative approaches for microsatellite propulsion with high specific impulse, high thrust, and continuous operation despite presence of solar eclipse.     

中继卫星系统仿真软件设计与应用*

设计开发中继卫星系统仿真软件,并针对理想信道条件、I/Q幅相不平衡、幅频特性、群时延、相位噪声、功放饱和条件、非线性信道条件这七种信道,仿真16QAM和16APSK的误码率性能,并对仿真结果进行分析。利用仿真平台得出的非线性信道条件下误码率需求与所需信噪比之间的关系,可以作为完善系统技术指标的重要依据,为中继卫星系统后续建设和应用提供重要参考。     

Simulator of pyroshock environment and effect rules of its adjustable parameters

During the launching of spacecraft, the on-board devices will undergo a series of pyroshock environments. In order to verify the reliability of these devices under these pyroshock environments, all of them are needed to take the shock test before launching. This paper has carried out an in-depth research on the simulation method of the pyroshock based on the true explosive excitation. In this study, a simulator containing multiple adjustment parameters is presented and the safety is considered by the design of the protective cover. And the working process of this setup is simulated with the explicit dynamic codes LS-DYNA. What’s more, the effects of the adjustment parameters on the three factors of shock Response Spectrum (SRS) of the resonant board are explored carefully. The rules achieved in this paper are verified by a typical example. The results indicate that the improved simulator can avoid the danger of explosive and make full use of the advantage of actual explosive excitation. And the test condition can be quickly realized at the simulator according to the effect rules of the three adjustable parameters.     

PM-TiAl 基合金热处理及其性能

为了优化TiAl合金的使用性能,本文研究了热等静压后的PM-TiAl基合金经过热处理后显微组织的变化情况及力学性能,发现其在热处理温度为1 355℃为全片层组织,在1 335℃为双态组织.全片层组织常温下的抗拉强度为446 MPa,随着温度的升高而增加;屈服强度为386 MPa,随着温度的升高而降低.     

扩频测控系统抗干扰性能及措施分析

测控设备处于纷繁复杂的电磁环境中,面临的各种干扰日益严重。本文对扩频测控系统抗各种形式的干扰性能进行了分析与比较。分析结果对扩频测控系统的设计及应用有一定的指导作用。     

民用飞机结构的全尺寸疲劳试验

进行全尺寸疲劳试验是新型民用飞机取得型号合格证的必要前提,也是对疲劳和损伤容限设计准则和评定技术的考核验证。从适航条例的最新要求出发,对民机结构的全尺寸疲劳试验作综述,并以波音777飞机的全尺寸疲劳试验为例,对试验相关的各项技术要点,特别是试验载荷谱予以阐述。     

一种用于导弹姿态控制系统的直接力非线性控制法

为改善传统导弹姿控系统线性控制法的不足,用相平面法分析了直接力作用下导弹的姿态运动规律和气动力作用对直接力控制的影响,提出了一种综合控制精度、姿控发动机产品特性和推进剂消耗量等指标的直接力非线性控制方法,给出了控制模型。仿真结果表明,该法能在气动力作用或干扰无法忽略的条件下实现导弹姿控发动机的开关工作正常,保证精度及推进剂消耗最省,其控制精度与线性比例微分(PD)控制律相当。     

具有星间链路的星座相位设计

通过分析星座空间构形的变化规律，综合考虑星座空间构形对地面覆盖特性、星间链路、空间测量精度以及工作性能的影响，利用改进的层次分析法对星座相位进行优化设计。通过对全球覆盖星座进行仿真，验证了方法的可行性。     

频率捷变时间精密测试系统

较详细地介绍了捷变时间的定义以及６种常用测量方法的原理、数据处理过程、及测量结果等内容。６种方法分别为检相－示波器法、鉴频－示波器法、检相－时间间隔计数器法、鉴频一时间间隔计数器法，ＨＰ５３７２Ａ测频和ＨＰ５３７２Ａ测相。给出了这几种测量方法的适用范围和优缺点。     

船舶齿轮箱振动测试分析及优化研究

齿轮箱是船舶动力传动系统的主要振源之一，为了研究船舶齿轮箱振动性能及优化措施，进而实现船舶的低噪声化，以本单位自主研发的船用齿轮箱为例，通过台架试验和振动频谱分析结合的方法分析齿轮箱振动的主要影响因素，对振动性能关键影响因素进行优化改进。本文结合振动频谱分析结果对齿轮箱从齿轮修形设计和液压供油系统改进两个方面进行了优化，并对采取优化措施后的齿轮箱进行振动试验验证和振动频谱分析。结果表明：齿轮修形和液压供油系统改进两项优化措施可以切实有效的改善齿轮箱的振动性能。在文中的齿轮箱案例中，齿轮修形后齿轮啮合频率处振动峰值下降40.2%，总振级下降1.85dB，进一步采取液压供油系统改进措施后，齿轮箱总振级下降9.99dB。齿轮修形和液压供油系统改进对船用齿轮箱振动性能提升具有工程应用价值。