天梯系统指标初步研究

天梯是一种将有效载荷从地球表面运输到空间的低成本解决方案,是未来航天运输系统的重点发展方向之一.对天梯系统规模和运载能力等指标的设计方法进行研究,给出了一种确定天梯系统规模及运载能力的基本方法和具体设计流程,分析了相关设计参数对天梯系统规模及运载能力的影响,为后续开展天梯方案论证提供了参考.     

中国航天运输系统未来发展展望

当前世界航天已发展到大规模进出空间新阶段,对航天运输系统发展提出了更高的要求。面向航天强国建设的历史使命,聚焦中国航天运输系统建设,研究了国外航天运输系统发展态势,总结了中国航天运输系统的发展现状,结合未来发展需求,提出了中国航天运输系统未来发展展望。     

美国可重复使用助推器发展综述

对美国未来航天运输系统研究中的可重复使用助推器(Reusable Booster Vehicle, RBV)技术的研发现状进行介绍.通过了解主要研发机构进行的相关型号研究,对美国RBV及相应航天运输系统的关键技术进行分析,并对未来发展方向进行展望,对新型航天运输系统的研发有一定借鉴意义.     

中国航天运输系统的发展与未来

航天运输系统作为一个国家开展航天活动的支撑和基础,是其综合国力的重要标志之一.在对当今世界各国航天运输系统发展新特点进行分析的基础上,针对我国航天运输系统所面临的国内外政治、经济、军事、科技发展需求带来的机遇与挑战,明确指出:未来我国需要建立相对完备的航天运输系统,需要完成以新一代运载火箭研制为核心的一次性运载火箭更新换代与新运载体系构建,需要开展以先进上面级技术为基础的轨道转移运输系统的研究,需要进行以部分重复使用为阶段目标的完全重复使用运载器的探索,需要跟踪国外新概念航天运输技术进展,需要不断完善、壮大和拓展整个运输体系.     

中国航天运输系统未来发展战略的思考

概括了航天运输系统的概念、任务、总体技术要求的发展变化,总结了国外航天运输系统的技术特点和发展状况,分析了我国航天运输系统的差距和不足,进而提出了我国航天运输系统未来的发展战略。     

法国高超音速飞机(AGV)和2000年航天运输系统(STS)使用的发动机

在本刊(AIR & COSMOS)介绍布尔日航展的一期中,曾介绍了法国航空航天公司在高超音速飞机、未来航天运输系统、赫尔姆斯接替者、阿里安5以及2000年航天运输系统(STS)领域内进行的研究。其结论之一是:这些飞行器采用哪种动力装置的问题是最紧迫、最有决定性的,同时又要求进行最深入的研究。     

增材制造技术在国外航天领域的研究应用现状

增材制造是一种新型的数字化制造技术,在航天领域得到了越来越广泛的应用。针对近几年国外在航天领域开展的增材制造技术研究与应用进行了调研分析,重点阐述了增材制造技术在国外航天运输系统、导弹武器系统、卫星系统以及太空制造中的研究应用情况。综合来看,国外航天领域增材制造技术正逐渐进入主流制造技术的行列。     

航天运输系统专利预警分析与应对模型构建研究

在航天运输系统领域,面对国外企业在中国大面积的专利部署,有必要建立专利预警分析与应对模型,以应对可能存在的专利侵权纠纷。研究提出构建航天运输系统专利预警分析与应对模型的步骤,重点提出专利预警警度的判断方法,使其满足军工企业知识产权管理模式。     

推动中国航天运输系统发展迈向世界航天强国

建设航天强国是当代航天人的神圣使命和光荣职责.在中国全面开展"十三五"布局的关键时期,抓住推行创新驱动及军民融合等重大发展战略举措的机遇,系统思考、顶层谋划航天技术未来发展,对实现航天强国建设目标具有重要意义.对标建设航天强国要求,提出了航天运输系统的发展目标、思路、重点及途径.     

航天运输系统对火箭发动机的需求

为推进中国航天推进事业的发展,从未来航天运输系统的任务需求出发,从大推力、高推质比、高比冲、泵后摆、可延伸喷管、推力调节、多次启动等7个方面提出对火箭发动机的发展方向和关健技术.最后根据中国航天运输系统的情况,对优先发展的技术进行了建议.     

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.