CZ-4C探月任务多星发射结构总体方案

为了建立嫦娥四号探测器在月球背面与地球之间的通信,并利用月球背面良好的低频辐射环境开展低频射电天文观测,根据嫦娥四号工程要求,需要发射一颗中继星及两颗月球轨道编队超长波天文观测微卫星至地月转移轨道.这是CZ-4C运载火箭首次被用于探月任务,为适应探月轨道一箭三星发射及未来深空探测任务需求,CZ-4C运载火箭针对探月任务的特点对构型进行了通用化设计.从整流罩选型、主星发射方案、搭载星发射方案等3个方向对CZ-4C探月任务多星发射结构总体方案的研制进行总结,为后续用于深空探测小卫星发射建立基础.     

基于末级钝化推力变轨的月球借力轨道设计

对于运载火箭发射探月返回飞行试验器任务,火箭末级会跟随试验器再入返回地球,因其再入速度快、落区散布范围广,存在严重的安全隐患.为解决末级再入带来的安全性问题,提出基于末级钝化推力变轨的月球借力轨道设计方法,使末级进入绕地月飞行的大椭圆轨道.利用钝化推力实现月球引力辅助变轨,进而达到优化绕地月飞行轨道近地点高度的目的.     

向月飞行轨道误差分析

根据月球探测器向月飞行轨道动力学方程式得到了飞行轨道误差的迭代方程,采用协方差分析方法对轨道初始误差误差源造成的轨道误差进行了分析,结合具体算例,给出了探测器初始轨道位置和速度误差引起的向月飞行轨道误差的时间历程和轨道终点误差。计算结果表明,若发射环月卫星,必须进行多次中途轨道修正。     

使用遗传算法和B平面参数进行月球探测器地月转移轨道设计

通过遗传算法和B平面参数对月球探测器地月转移轨道进行了设计和计算，计算结果表明，结合遗传算法和B平面参数可以很好地解决探月轨道搜索的全局性和快速收敛性问题。     

雅典娜2成功发射月球勘探者号探测器

雅典娜２成功发射月球勘探者号探测器美国洛克希德－马丁公司的雅典娜２火箭（即原来的ＬＭＬＶ２）于１９９８年元月６日从卡纳维拉尔角成功地把月球勘探者号探测器送入了轨道。这是这种火箭的首次发射，发射费为２５００万美元。此前，运载能力较小的雅典娜１火箭（即原...     

月地返回轨道参数的初步分析

对月球探测器的返回轨道进行建模与参数分析.基于双二体假设,在三维空间中建立返回轨道的数学模型;根据模型计算给出初步设计轨道的算例,并以此结果为初值,在已有高精度动力学模型下搜索计算,较快地得到了精确轨道参数;通过两条轨道参数的对比,证明文中初步设计解析方法的正确性;通过对模型进行仿真计算,得到落区位置等因素对近月点机动...     

空间探测器飞行原理

空间探测器离开地球时必须获得足够大的速度才能克服或摆脱地球引力,实现深空飞行。探测器沿着与地球轨道和目标行星轨道都相切的日心椭圆轨道（双切轨道）运行,就可能与目标行星相遇,或者增大速度以改变飞行轨道,可以缩短飞抵目标行星的时间。例如,美国旅行者2号探测器的速度比双切轨道所要求的大0.2公里/秒,到达木星的时间缩短了将近四分之一。     

长征五号运载火箭探火轨道高精度制导技术

长征五号火箭发射天问一号探测器进入地火转移轨道(探火轨道),是中国航天60年来首次冲出地球束缚、奔向火星.针对长征五号运载火箭将有效载荷送入地火转移轨道的适应性难题,提出了一种适应探火轨道的高精度制导技术,并给出了制导设计方案及相应的仿真结果.长征五号火箭探火轨道高精度制导技术实现了火星探测器的高精度入轨,入轨指标达到了工程任务要求的百分之三的量级,标志着中国火箭具备执行地外行星探测任务的能力.     

嫦娥”探月工程梗概

20世纪60年代至70年代，美国、前苏联曾竞相开展探月、登月活动，先后发射了数十个月球探测器。“阿波罗”计划完成后，月球探测一度陷入低迷状态。20世纪90年代以来，新一轮月球探测的热潮再度掀起。美国宣布将于2015年重返月球；2003年9月欧洲发射了SMART-1号月球探测器；日本也将月球探测定为其星球探测计划的首要目标；印度也提出将在2007年左右发射月球卫星，2015年前实现航天员登月。     

国外航天飞机和空间站的研制经费

美苏等工业国家早已开始竟相发展空间技术,25年来(1961～1983年)在空间开发和应用上耗资4000亿美元。其中,美国利用土星等四种类型运载火箭,1964年发射了第一颗对地静止通信卫星,1966年首次实现轨道对接,1969年宇航员第一次登上月球,1981年进行第一次可重复使用型载人飞船飞行等共耗资1400亿美元;苏联利用质子号等六种运载火箭,1957年发射了第一颗人造地球卫星,1961年进行了第一次载人空间飞行,1982年4月又发射了新     

Stability of the Third Generation Intensifier under Illumination

The stability under illumination of transmission-mode GaAs photocathode sealed in the third generation intensifier is investigated by use of spectral response testing instruments. The variations of spectral response with the illumination times under weak and intense illumination are compared. The variations of photoemission performance parameters are also characterized. The results show that during initial several weak illuminations photocathode behaves no evident decay and a maximum sensitivity is achieved, while under intense illumination the sensitivity of photocathode begin to decrease largely at the first illumination. The calculated performance parameters show that the variation of surface escape probability with illumination times is a direct cause of instability of photocathode. It is also found that under intense illumination peak wavelength is moved towards short-wave and peak response is decreased, which shows that the ability of long-wave response of photocathode is decreased.     

Passive Acoustic Radar for Detecting Supersonic Cruise Missile

A Passive Acoustic Radar is presented as a necessary complement to electromagnetic wave radar, which will be expected to be an effective means for detecting cruise missiles. Acoustic characteristics of supersonic flying projectiles with diverse shapes are expounded via experiment. It is pointed out that simulation experiment could be implemented using bullet or shell instead of cruise missile. Based on theoretical analysis and experiment, the ““acoustic fingerprint““ character of cruise missile is illustrated to identify it in a strong noise environment. After establishing a locating mathematical model, the technique of acoustic embattling is utilized to resolve a problem of confirming the time of early-warning, considering the fact that velocity of sound is much slower than that of light. Thereby, a whole system of passive acoustic radar for detecting supersonic cruise missile is formed.     

Super-resolution Restoration of Remote-sensing Images

A novel image restoration scheme, which is super-resolution image restoration algorithm Poisson-maximum-afterword-probability based on Markvo constraint （MPMAP） combined with evaluating image detail parameter D, has been proposed. The advantage of super-resolution algorithm MPMAP incorporated with parameter D lies in the fact that superresolution algorithm MPMAP model is discrete, which is in accordance with remote-sensing imaging model, and the algorithm MPMAP is proved applicable to linear and non-linear imaging models with a unique solution when noise is not severe. According to simulation experiments for practical images, super-resolution algorithm MPMAP can retain image details better than most of traditional restoration methods; at the same time, the proposed parameter D can help to identify real point spread function （PSF） value of degradation process. Processing result of practical remote-sensing images by MPMAP combined with parameter D are given, it illustrates that MPMAP restoration scheme combined PSF estimation has a better restoration result than that of Photoshop processing, based on the same original images. It is proved that the proposed scheme is helpful to offset the lack of resolution of the original remote-sensing images and has its extensive application foreground.     

Design and Simulation of TF and TA Controller for Missile

A nonlinear terrain following(TF) and terrain avoidance(TA) controller is proposed for missile control systems. Based on classical TF algorithm (adaptive angle method), a new method for TF controller is proposed by using angle of attack. A method of obtaining terrain outline data from digital elevation map (DEM) for TF control is discussed in order to save store space. A TA algorithm is proposed by using bank-to-turn technique. The block control model, which is suitable for backstepping design, is given for nonlinear model of missile. Making full use of the characteristics of the system and combining block control principle and backstepping technique, a robust controller design method is proposed. Uncertainties in every sub-block are allowed, and can be canceled by using the idea of nonlinear damping. It is proved that the state tracking errors are converged to a neighborhood of the origin exponentially. Finally, nonlinear six-degree-of-freedom simulation results for the missile model are presented to demonstrate the effectiveness of the proposed control law.     

Design and Analysis of Test Schemes of Static Postponing Time on Shrapnels Used to Riot Control

The test scheme of static postponing time given in our actual national military test standard on shrapnels used to control riot is a nine-point test scheme on the combined action of three kinds of temperatures and three kinds of pressures,the consumed ammunitions are more excessive. Statistic analysis and tentative checkout about a lot of test data are done,feasibility gists are put forward for optimizing of the test design scheme. The optimizing design and data analysis of test scheme of the item are done by managing uniformity design theory, two scientific and reasonable six-point test schemes are confirmed. The feasibility and reliability of the optimizing design schemes put forward above are proved ulteriorly by test validating. The gained schemes not only have good design uniformity and little ammunition wastage and meet the test demand, but also have better forecast ability for the result data of other points using the mathematic models from the actual test points.     

Design of Non-fragile Satisfactory Estimator for Linear Continuous Perturbed Stochastic Systems

The design problem of non-fragile estimator is addressed for a class of perturbed linear continuous systems. The perturbations occur on the plant and estimator parameters. The estimator designed should force the error system to achieve the desired decay rate and force the steady error variance less than the specified upper bound irrdevancy of the admissible plant perturbations and estimator perturbations. Consistency problem of the decay rate with the variance upper bound is first considered via linear matrix inequality （LMI） approach. The solution of the estimator parameter under specifications to be consistent is then discussed. The consistency condition of specifications and estimator parameter solution are transformed to feasible or minimum problems subject to a set of LMI respectively. The method is illustrated by a numerical example.     

An Improved Scene-based Nonuniformity Correction Algorithm for Infrared Focal Plane Arrays Using Neural Networks

The improved scene-based adaptive nonuniformity correction （NUC） algorithms using a neural network （NNT） approach for infrared image sequences are presented and analyzed. The retlna-like neural networks using steepest descent model was the first proposed infrared focal plane arrays （IRFPA） nonuniformity compensation method, which can perform parameter estimation of the sensors over time on a frame by frame basis. To increase the strength and the robustness of the NNT algorithm and to avoid the presence of ghosting artifacts, some optimization techniques, including momentum term, regularization factor and adaptive learning rate, were executed in the parameter learning process. In this paper, the local median filtering result of Xij （ n ） is proposed as an alternative value of desired network output of neuron Xij （ n ）, denoted as Tij （ n ）, which is the local spatial average of Xij （ n ） in traditional NNT methods. Noticeably, the NUC algorithm is inter-frame adaptive in nature and does not rely on any statistical assumptions on the scene data in the image sequence. Applications of this algorithm to the simulated video sequences and real infrared data taken with PV320 show that the correction results of image sequence are better than that of using original NNT approach, especially for the short-time image sequences （several hundred frames） subjected to the dense impulse noises with a number of dead or saturated pixels.     

Piecewise Filter of Infrared Image Based on Moment Theory

The disadvantages of IR images mostly include high noise, blurry edge and so on. The characteristics make the existent smoothing methods ineffective in preserving edge, To solve this problem, a piecewise moment filter （PMF） is put forward. By using moment and piecewise linear theory, the filter can preserve edge. Based on the statistical model of random noise, a related-coefficient method is presented to estimate the variance of noise. The edge region and model are then detected by the estimated variance. The expectation of first-order derivatives is used in getting the reliable offset of edge. At last, a fast moment filter of double-stair edge model is used to gain the piecewise smoothing results and reduce the calculation. The experimental result shows that the new method has a better capability than other methods in suppressing noise and preserving edge.     

Bistatic Sonar Localization Based on Best Linear Unbiased Estimation

A best linear unbiased estimation （BLUE） algorithm for bistatic sonar localization is proposed. The Cramer-Rao bound for bistatic Sonar and the geometrical dilution of precision （GDOP） in different conditions are given. The simulation results show that the location accuracy of BLUE algorithm is higher than the weighted least square method.     

Research on Gear-broken Fault Diagnosis in a Tank Gearbox

A fault diagnosis method of working position gear in a tank gearbox is put forward based on simulating the fault of working position gear in an actual tank, extracting the envelope of vibration signal by Hilbert transformation amplitude demodulation method, and zooming the low-frequency band to envelope signal.