Characteristics of the telescope Gamma-1 in the coded aperture mode

The efficiency of using the coded aperture on the Gamma-1 telescope to solve a variety of astrophysical problems has been considered. The coded aperture technique is shown to be at a disadvantage in relation to the conventional one so far as discriminating a source from the background is concerned. However, for powerful sources the coded aperture technique has an advantage from the viewpoint of accuracy of source location on the celestial sphere, the resolution of closely spaced sources and the determination of the sizes of sources.     

Optics of the far infra-red and submillimetre space telescope

Some of the considerations in the design of the telescope for FIRST are discussed. It is pointed out that instruments that operate at submillimetre wavelengths need to be analyzed with techniques derived from both the Radio and Optical/IR traditions. The issue of emissivity of reflector surfaces is also discussed.     

The future of space infrared astronomy

Conclusion I can remember vividly when Tim Hawarden first came into my office about 7 years ago and talked very excitedly about passively-cooled space infrared telescopes. He was sufficiently persuasive that we even managed to get the idea into the various forward-look exercises in which the SERC indulges every year. The idea has evolved considerably since then and the climax of that activity was when Tim presented the case for POIROT to the European Space Agency a couple of years ago. The project did very well indeed as it passed through the peer-review committees and was unlucky just to miss being selected for further study.Since then, the momentum has continued largely through the enthusiasm of Tim and of Harley Thronson's advocacy in the USA. It is my view that the time has come when the agencies have to take these proposals very seriously indeed as the way forward for space infrared astronomy. Our goal over the next two days is to expose all the issues which have to be addressed to convert the concept into a realistic space mission.     

Radiative and hybrid cooling of infrared space telescopes

The designs of cold space telescopes, cryogenic and radiatively cooled, are similar in most elements and both benefit from orbits distant from the Earth. In particular such orbits allow the anti-sunward side of radiatively-cooled spacecraft to be used to provide large cooling radiators for the individual radiation shields. Designs incorporating these features have predictedT _tel near 20 K. The attainability of such temperatures is supported by limited practical experience (IRAS, COBE). Supplementary cooling systems (cryogens, mechanical coolers) can be advantageously combined with radiative cooling in hybrid designs to provide robustness against deterioration and yet lower temperatures for detectors, instruments, and even the whole telescope. The possibility of such major additional gains is illustrated by the Very Cold Telescope option under study forEdison, which should offerT _tel5 K for a little extra mechanical cooling capacity.     

Conceptual design of near-space synthetic aperture radar for high-resolution and wide-swath imaging

Airborne synthetic aperture radar (SAR) has the capability of high-resolution, and spaceborne SAR has the capability of wide-swath. Inspired by recent advances in near-space defined as the region between 20 km and 100 km, this paper conceptually designed near-space vehicle-borne SAR. The near-space vehicle-borne SAR has the synthetical advantages of the satellite and airplane platforms. By placing SAR transmitter or receiver in near-space vehicles, many functions that are currently performed with satellites or airplanes could be performed in low cost way. These advantages make simultaneous high-resolution and wide-swath SAR imaging possible. As such, this paper focuses on the role of near-space vehicle for high-resolution and wide-swath SAR imaging, and deals with conceptual performance, as opposed to technological implementation. The concepts, models and processing algorithms are provided. To further suppress the azimuth ambiguities and extend swath width, multiple beams in azimuth is applied. Furthermore, an example near-space vehicle-borne SAR is designed. It is shown that the use of cost effective near-space vehicles can provide the solutions that were previously thought to be out of reach for remote sensing scientists and customers.     

Control of a large space structure using MMAE/MMAC techniques

The application of moving-bank multiple model adaptive estimation and control (MMAE/MMAC) algorithms to an actual spade structure (Space Integrated Controls Experiment (SPICE)) being examined at Phillips Laboratory at Kirtland AFB, NM, is presented. The structure consists of a large platform and a smaller platform connected by three legs in a tripod fashion. Kalman filtering and LQG (linear system, quadratic cost, Gaussian noise) control techniques are utilized as the primary design tools for the components of the MMAE/MMAC. Implementing a bank of filters or controllers increases the robustness of the algorithms when uncertainties exist in the system model, whereas the moving bank is utilized to reduce the computational load. Several reduced-order models are developed from the truth model using modal analysis and modal cost analysis. The MMAE/MMAC design with a substantially reduced-order filter model provides an excellent method to estimate a wide range of parameter variations and to quell oscillations in the structure.     

Development of a 1m-normal-incidence-EUV telescope

Astrophysical plasmas at temperatures in the range (0.5–5)×10⁵ K that occur e.g. in interstellar space, in the extended atmospheres around stars of essentially all spectral types, including the numerous late-type stars with low photospheric temperatures, and in the atmospheres of highly evolved stars, can best be studied at extreme ultraviolet wavelengths where they release the bulk of their energy. We report here the current development status of a 1m-normal-incidence-EUV-telescope that will be flown on an ARIES rocket to observe the spectra of nearby stars in the 350 – 700 mm range.     

Simple adaptive control of large flexible space structures

Simple adaptive control procedures that do not require explicit parameter identification have been shown to be fit for control of large systems such as flexible structures. It is of interest, however, to test their robustness when fast adaptation is needed or when the resulting adaptive control system must confront finite sensor and actuator dynamics or parasitic disturbances. Flexible structures case studies using parallel feedforward and simplified adaptive controllers are used to present a robust adaptive control solution to these problems. The detailed proof of robust stability of the adaptive control system is also presented. Simulations illustrate the simplicity of implementation and the power of the proposed algorithm in difficult realistic situations     

某型箔条/红外干扰弹投放器检测系统

为了实现干扰弹投放器的快速自动检测，在对其电子电路系统的工作原理进行深入分析的基础上，设计开发了一种新型干扰弹投放器检测系统，并详细介绍了系统的软硬件设计方案，该系统专用于某型干扰弹投放器的电子电路系统装机前的内场综合检验和测试，实现故障的实时诊断和定位。     

大型回流边界层风洞的气动与结构设计

大型边界层风洞是开展风工程研究的必备装备。以浙江大学ZD-1边界层风洞的研制为背景,详细介绍了大型回流边界层风洞气动设计和立式结构设计中的关键问题,在风洞气动设计时采用了收缩比为4∶1的单回路单试验段气动轮廓,在试验段中设置了0．22°的当量扩散角,对拐角导流片外形作了特殊处理,并采用钢结构与混凝土结构相结合的立式结构。流场校验结果表明,大型回流边界层风洞的气动与结构设计能满足设计要求,某些指标甚至达到航空风洞的标准,在试验段中设置扩散角有利于降低轴向静压梯度,立式结构设计对提高试验段气流的水平均匀性有一定的作用,可为今后类似风洞的研制提供参考。     

红外辅助着陆及DGPS/RA精密进近系统设计

介绍了红外辅助着陆及DGPS/RA精密进近系统的设计.该系统可提高飞机对野外机场的适应能力和着陆阶段的干扰能力.     

大型后掠自适应风力机叶片的气动扭角设计优化

针对大型后掠式自适应叶片(STB)中显著的气动/结构耦合现象,利用优化方法探讨了直叶片转化为后掠式自适应叶片后的气动扭角补偿优化,STB叶片没有不改变原直叶片的输出功率和结构强度。优化算法采用遗传算法,以功率为约束条件,扭角分布为优化变量,优化目标为叶片根部应力最小。建立了叶片的气动模型和六自由度铁摩辛科悬臂梁结构模型,叶片的气动特性分析采用了基于动量叶素理论的数值算法,结构特性分析采用有限元法,优化算法采用遗传算法。最后在额定风速条件下,完成了2.0MW叶片的气动扭角的补偿设计优化。分析结果表明,STB叶片通过扭角补偿后,可满足功率输出的要求,并大幅降低叶片的轴向推力。     

Predefined-time controller design for a multiple space transportation robots system based on Lp-Norm-Normalized Sign Function

This paper presents a predefined-time controller for Multiple Space transportation Robots System(MSRS), which can be applied in on-orbit assembly tasks to transport modules to pre-assembly configuration quickly. Firstly, to simplify the analysis and design of predefinedtime controller, a Predefined-time Stability Criterion is proposed in the form of Composite Lyapunov Function(CLF-PSC). Besides simplicity, the CLF-PSC also has the advantage of less conservativeness due to utilization of initial state information. Secondly, a concept of LpNorm-Normalized Sign Function(LPNNSF) is proposed based on the CLF-PSC. Different from traditional norm-normalized sign function, the Lp-norm of LPNNSF can be selected arbitrarily according to practical control task requirements, which means that the proposed LPNNSF is more generalized and more convenient for calculation. Thirdly, a predefined-time disturbance observer and predefined-time controller are designed based on the LPNNSF. The observer has the property of predefined-time convergence to achieve quicker and more accurate estimation of the lumped disturbance. The controller has less control input and chattering phenomenon than traditional predefined-time controller. In addition, by introducing the observer into the controller, the closed-loop system enjoys high precision and strong robustness. Finally, the effectiveness of the proposed controller is verified by numerical simulations. By employing the controller, the MSRS can carry assembly modules to the desired pre-assembly configuration accurately within predefined time.     

海军导弹通用测试系统软件的设计与实现

阐述了一种通用测试系统软件平台的功能、原理、结构和设计方法.     

空间目标逆轨网捕拦截停泊轨道的优化设计

为了提高对空间目标的拦截成功率,可采用拦截器从停泊轨道转移进入拦截轨道逆轨网捕拦截的方式。利用椭圆弹道理论,讨论和分析了该拦截方式停泊轨道优化问题的描述、模型的建立及优化的方法。计算结果表明,对该拦截方式所建立的模型和采用的优化方法满足逆轨拦截对轨道设计的要求,可为空间快速拦截应用提供理论借鉴和参考。     

Flow field design and experiment of high-efficiency electrochemical milling with large machining area

Materials that are difficult to cut, such as titanium alloys, are widely used in large loadbearing integral components of aircraft, leading to great challenges for manufacturing. Electrochemical milling is a way for machining difficult-to-cut materials through Computer Numerical Control（CNC） trajectory motion. Using a tilted large cathode machining surface and the cut-in feed mode, an efficient and low-cost method is obtained for machining the large integral components. A novel crossed and inclined structure of the flow mode is designed to realize electrochemical milling with a large tilted cathode surface. Compared to the vertical flow mode with one inlet, the proposed flow mode has two inlets that independently supply electrolytes, and the inclined channels make the flow field more stable. Flow field simulations are performed for both the vertical and proposed flow modes. The results show that the proposed flow mode avoids the random diversion of electrolytes and the ultralow flow velocity at both ends of the nozzle area, improving the velocity,uniformity, and stability of the electrolytes. The inclination angle of the crossed and inclined flow field is optimized. Finally, limit feed rate experiments are conducted in two modes, and the limit feed rate is 70 mm/min in the proposed mode. A sector workpiece of a large circular surface with approximately 8.77 mm thickness is machined 9 times by the cut-in electrochemical milling, the material removal rate is 4872 mm³/min, and the surface roughness is superior to 1.15 μm.     

基于概率方法的航天器姿态控制系统参数设计

针对传统航天器控制系统参数设计方法中存在的设计保守、主观经验性较强等缺点,使用概率分布对参数不确定性进行量化描述,采用概率指标代替确定性指标,对参数随机分布的系统进行概率分析,并使用可行域图对设计空间进行表征。在此基础上,应用概率优化方法对控制器参数进行优化设计。最后,通过实例对提出的方法进行仿真验证。仿真结果表明,概率分析方法能够放宽参数的设计空间,通过概率优化方法可以得到满足概率指标要求的设计结果,提高了设计效率。