飞行器性能样机虚拟试验系统研究与实现

为实现航天飞行器研制中性能样机模型的充分利用,提出了飞行器性能样机虚拟试验系统的总体方案,通过试验基础数据库、试验数据管理、验证辅助工具、虚拟试验应用等子系统划分和工作流程设计,提供对虚拟试验的全流程支持。系统突破了试验数据对象化管理、试验流程建模等关键技术,并基于虚拟试验支撑平台VITA完成了相应系统实现,在多个飞行器研制过程中开展了典型应用。     

超高速高空低动压柔性罩体脱落天地相关性研究

柔性罩体包裹于飞行器外表面,在飞行中段起到保护作用.再入过程中在气动力/热共同作用下,从飞行器表面拉开、脱落,脱落过程产生的附加干扰力/力矩,对飞行器再入姿态产生影响,造成惯性落点偏差.采用地面风洞模拟超高速高空低动压环境,考核不同再入动压条件下,罩体连接绳在气动力作用下的脱开过程,以及脱落过程对飞行器产生的干扰力/力矩.根据动态相似准则,将地面试验条件下罩体模型的脱落历程推导到飞行条件,建立刚体动力学仿真模型计算落点,与无干扰模型的理论落点对比,采用概率统计的方法分析罩体脱落引起的飞行器落点偏差,为罩体连接形式的优化设计提供支撑.      

超导磁悬浮支承系统干扰力矩及漂移误差分析

在超导磁悬浮支承系统中, 如果被悬浮的超导球形转子是一个理想的球体, 并且是表现出完全的迈斯纳态, 那么由于球体的对称性, 就不会产生干扰力矩. 但实际的情况并非如此, 一般情况下, 超导球形转子总是存在加工制造误差, 且在高速旋转时总是存在离心变形, 因此转子的表面并不是理想的球面, 当超导转子悬浮在磁场中时, 沿转子表面法线方向的磁悬浮力, 不是完全通过转子质心, 将会产生磁支承干扰力矩, 从而引起转子的漂移误差. 本文从超导转子磁支承干扰力矩的物理机理出发, 对干扰力矩及其引起的漂移误差进行了分析, 包括转子非球形产生的一次干扰力矩、转子非球形与失中度和装配误差产生的二次干扰力矩, 并推导出了磁支承干扰力矩引起的漂移率计算公式, 代入转子参数计算出各种干扰力矩引起的漂移率大小, 为转子漂移测试和系统误差补偿提供了参考, 对于转子的结构优化设计具有指导意义.     

星载测量通信系统模拟器设计与实现

为了在地面对星载测量通信系统之间互联互通性能进行测试评估,设计了一种可替代星载测量通信系统的地面模拟器,该模拟器由收发信机,时频单元,信道仿真器以及管理控制计算机构成,收发信机采用双FPGA架构设计,支持星间信号的收发处理,在功能性能指标方面与星载设备具有良好的一致性,信道仿真器能够实现信号传输延时、多普勒以及衰落特性的实时仿真,可显著增强试验场景的真实性以及评估结论的可信性。互联互通试验过程表明,该模拟器功能齐全、性能可靠、操控简单并且易于搬运,试验结果有效验证了星间互联互通方案的可行性。     

总体电路瞬态浪涌抑制

航天系统设备多,负载特性复杂,产生的瞬态浪涌电流通常对航天飞行器电气系统总体电路的危害很大。为了解决航天飞行器电气系统中瞬态浪涌如何有效抑制的问题,本文从瞬态浪涌形成的原理、影响及测量方法出发,在电气系统总体设计角度,分别从浪涌抑制电路、负载分配策略、负载休眠唤醒工作模式三方面提出了串电阻法、软启动法、负载休眠唤醒法等多种解决方案,通过搭建仿真试验平台和实物试验平台开展了相应的试验验证,瞬态浪涌电流得到了有效抑制。     

虚拟试验支撑框架VITA研究与实现

虚拟试验验证技术可为复杂航天产品的试验验证提供有效的技术支撑。本文主要介绍了虚拟试验支撑框架VITA研究与实现情况,包括其系统组成及主要技术特点,重点介绍系统实现方案及其在飞行器研制过程中的应用情况。实践表明VITA支持对产品关键系统的技术性能验证,有效解决了产品难以开展大系统联合试验的难题。     

如此称重准确吗

通过对“ 双秤砣”法称重的准确性进行分析, 将力矩平衡问题与实际生活应用联系起来     

某型导弹发射装置平衡机的改装设计

根据某试飞器发射装置改装方案,在对平衡机工作原理研究的基础上对某型导弹发射装置平衡机进行了改装设计;根据平衡机的设计原则,分析了平衡机的工作原理,计算了带弹和不带弹定向器的重量力矩,由此进行了平衡机的弹簧结构参数和平衡性能参数计算;通过对平衡力矩曲线和高低机负载曲线进行分析讨论,文章设计的方案中,平衡机的平衡力矩曲线与理想情况相符,切不平衡力矩曲线变化较为平缓,设计结果符合方案要求,且改装工作量小。     

分布式负载垂直极化有界波电磁脉冲模拟器外泄场的规律分析

将基于MPI平台的并行时域有限差分(FDTD)方法与基于完全磁导体(PMC)镜像法相结合,并结合CST模拟软件,模拟给出分布式负载垂直极化有界波电磁脉冲(EMP)的外泄场(包括侧泄场和后泄场)的分布规律。模拟结果与实验结果符合得很好。研究表明:在高度方向上,地面附近的外泄场峰值最大,但远离模拟器时,在1.5 m高的高度范围内,外泄场的峰值差别不大;不管采用何种双指数脉冲源,距离模拟器边缘位置比较近的测点在传输线段的侧泄场的幅值大于分布式负载段侧泄场的幅值,且两者都大于分布式负载末端的后泄场幅值,但随着测点与模拟器边缘的垂直距离的增加,分布式负载段的后泄场可能会比侧泄场大;对于电压峰值相同的双指数激励源而言,所含的高频分量越多,在一定范围内,从其分布式负载末端外泄的后泄场更大;模拟器下方大地的电导率增加,模拟器的外泄场增加。     

一种虚实结合的联合试验系统及方法

虚拟试验正朝着“虚实结合”和“综合集成”的方向发展,将实物设备与数学模型集成起来进行联合试验现已成为虚拟试验中“虚实结合”的有效手段,文章给出了一种将实物设备与数学模型进行联合试验的系统及方法,设计了模型包装器、实时网与RTI网的桥接器,论述了系统的时间管理方式,并在某型号的联合试验中得到了验证,将以反射内存网连接的半实物系统与以HLA连接的防御系统互联进行联合试验,考核型号的总体指标,应用表明该系统与方法具有良好的复用性、可扩展性和互操作性。     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.