电推进技术的应用与发展趋势

扼要介绍了电推进技术的发展历史，概述了不同形式(电热、电磁和静电三大类)电推力器的特点及应用情况．指出了为满足不同空间任务电推进的发展趋势；并根据我国的研究状况、存在的问题和差距，提出了加快发展我国电推进技术的意见。     

薄片状聚酰亚胺多孔材料的研究进展

综述了薄片状聚酰亚胺多孔材料的研究进展,主要介绍了薄片状的聚酰亚胺多孔材料的产品种类、研究单位、性能指标、应用情况及制备方法,并提出了目前对薄片状聚酰亚胺多孔材料研究存在的问题以及研究现状,展望了薄片状聚酰亚胺多孔材料在今后的研究方向和发展趋势.薄片状聚酰亚胺多孔材料,已经作为垫片用在宇宙飞船的多层隔热系统中,甚至会逐渐替代传统的多层隔热系统材料.     

涡轴发动机技术参数与发展趋势评估

为了给先进涡轴发动机总体性能设计和尺寸与重量计算提供技术参数选择依据,本文收集10台一至四代国外典型的涡轴发动机技术参数,建立总体性能计算和尺寸与重量联合计算的涡轴发动机技术参数评估模型并开发计算程序,利用计算程序对收集的技术参数进行评估,获得涡轴发动机技术参数的水平和发展趋势,并预测下一代先进涡轴发动机的技术参数;以技术参数发展趋势为基础,研究各部件主要的气动、结构、强度、材料参数变化对涡轴发动机性能的影响。获得的涡轴发动机技术参数发展规律及其对发动机性能参数的影响,为先进涡轴发动机总体设计提供了依据。     

Telecommunications Technology in Metropolitan Areas

The electronic communication technology available today offers the possibility of changing many patterns of information transfer in urban areas. There are three major trends which are converging to make this change possible. These are: 1) the technology to permit wideband information transfer manifested in the existing 2300/CATV/Cable System and in modification of the Bell network for wideband services; 2) the potential demand for a vast range of new services to persons operating in the urban areas; 3) the increasing demands for meeting mobile information transfer needs in the urban areas through radio systems operating in the 100 to 1000 MHz part of the spectrum. The extent to which these trends are allowed to converge will be a function of the quality of telecommunication policy formulation and execution. In order to formulate policy, it is necessary to have a vision of the future toward which to work. This paper will discuss the types of services possible with the technology presently available, which will have impact on future policy decisions.     

我国改革开放以来发展观的演进

中国改革开放三十年来发展观的变迁经历了三个时期:自发地采用以经济增长为核心发展观的时期;自觉反思和探索发展观的时期;形成和实践科学发展观理论体系的时期。发展观的演进一方面受到国内外思潮的影响,另一方面又受到国内经济社会发展状况的制约。评价发展观的标准是其能否适应时代需求,滞后或过于超前都会带来负面的影响。     

Trends in the Neutral and Ionized Upper Atmosphere

This article reviews our knowledge of long-term changes and trends in the upper atmosphere and ionosphere. These changes are part of complex and comprehensive pattern of long-term trends in the Earth’s atmosphere. They also have practical impact. For example, decreasing thermospheric density causes the lifetime of orbiting space debris to increase, which is becoming a significant threat to important satellite technologies. Since the first paper on upper atmosphere trends was published in 1989, our knowledge has progressed considerably. Anthropogenic emissions of greenhouse gases affect the whole atmosphere, not only the troposphere. They cause warming in the troposphere but cooling in the upper atmosphere. Greenhouse gases such as carbon dioxide are not the only driver of long-term changes and trends in the upper atmosphere and ionosphere. Anthropogenic changes of stratospheric ozone, long-term changes of geomagnetic and solar activity, and other drivers play a role as well, although greenhouse gases appear to be the main driver of long-term trends. This makes the pattern of trends more complex and variable. A?consistent, although incomplete, scenario of trends in the upper atmosphere and ionosphere is presented. Trends in F2-region ionosphere parameters, in mesosphere-lower thermosphere dynamics, and in noctilucent or polar mesospheric clouds, are discussed in more detail. Advances in observational and theoretical analysis have explained some previous discrepancies in this global trend scenario. An important role in trend investigations is played by model simulations, which facilitate understanding of the mechanisms behind the observed trends.     

Space power systems requirements and issues: the next decade

Some of the more important space power technology issues, requirements, and challenges of the 1990s are described, and the impact of new component technology on the overall performance of space power systems is assessed. Advanced component, subsystem and system technologies that will significantly affect the performance, reliability, and survivability of next-generation baseload and burst mode space power systems are emphasized. Technology disciplines related to power sources (solar/nuclear and chemical), power conversion, energy storage, power conditioning/distribution and control, and waste-heat acquisition, transport, and rejection are primarily addressed. For some of them, performance trends that can be used as the basis for projecting future advanced power-system performance are developed. Performance capabilities for several different types of space power system for both baseload and burst mode applications are postulated on the basis of evolving technology and point designs that incorporate projections of advanced component capabilities     

空气流速和自热效应对湿度传感器测量准确度的影响

通过对多种典型型号湿度传感器在不同空气流速条件下对同一相对湿度测量结果的变化的实验研究,得出了0～1.5 m/s流速范围内湿度传感器的示值随流速的变化趋势,即示值随流速增大而增大,总变化量最大达2%RH以上,且变化主要发生0.5 m/s以下的低流速情况下,同时传感器表面温度随流速增大而降低,两者变化趋势相互吻合。进一步分析表明,上述现象是湿度传感器的自热效应和空气与传感器之间的对流换热效应共同作用的结果,它给湿度传感器的测量结果带来新增不确定度。     

未来空天一体化力量的发展方向探讨

分析了空天一体化力量在未来战争中的重要作用,以及国外空天一体化力量的发展概况和发展趋势.在此基础上,重点探讨了我国空天一体化力量未来发展的五个主要方向.最后,针对世界空天一体化力量的发展趋势,结合我国具体国情给出了几点建议.     

Industrial battery technologies and markets

Industrial battery market segments generally fall into two major categories--traction batteries, also called motive power batteries; and stationary batteries, also referred to as standby power batteries. The major industrial battery subcategories are discussed. Industrial trucks and rail and mine vehicles represent two major subcategories of motive power batteries. Industrial trucks include forklifts, automated guided vehicles (AGVs), various types of towing vehicles, floor cleaning equipment and so forth. Battery-powered rail and mine vehicles are used in mines where gas is present that could be ignited by spark ignition engines. Locomotive starting batteries and railcar emergency power batteries are also included in the second subcategory. The distinction is beginning to blur between valve-regulated industrial batteries and golf cart or marine batteries. Both industrial and SLI(starting/lighting/ignition)-derivative batteries are competing for markets in the future. The future trends in industrial battery production in Japan, USA and Europe are discussed     

Implications for Entry Level Test Professionals

This paper discusses the product and manufacturing trends that are currently impacting the testing function. In addition, since educational experiences relevant to testing is minimal at most universities, the impact of current and future trends in testing are noted.     

国外航天运输系统防热系统,结构和材料的总体分析研究

对近年来国外航天运输系统包括飞船、航天飞机和空天飞机等的防热方案的选用方向、防热结构和防热材料的研究与应用以及发展方向进行了高度概括与分析，采用了新的分类方法，介绍了各种新型的防热系统、结构和材料。     

Design by extrapolation: an evaluation of fault tolerant avionics

Over the past 30 years, safety-critical avionics systems such as Fly-By-Wire (FBW) flight controls, full-authority digital engine controls, and other systems have been introduced on many commercial and military airplanes and spacecraft. Early FBW systems, such as on the F-16 and Airbus A320, were considered revolutionary and introduced with extreme caution. These early systems and their successors all make use of redundant and fault-tolerant avionics to provide the required dependability and safety, but have used significantly different architectures. This paper examines the different levels of criticality and fault tolerance required by different types of avionics systems, establishes architectural categories of fault-tolerant architectures, and identifies the discriminating features of the varied approaches. Examples of discriminators include the level of redundancy, methods of engaging backup systems, protection from software errors, and the use of dissimilar hardware and software. The strengths and weaknesses of the approaches will be identified. The paper concludes with some speculation on trends for future systems based on this evaluation of previous systems     

裂纹参数和筋条布局对共振九宫板动态应力强度因子的影响

由于裂纹的出现会改变振动结构的断裂行为,本文建立了含中心裂纹九宫板结构的有限元模型并采用模态叠加原理快速求解出该结构在共振条件下的裂纹尖端应力强度因子（SIF）,然后分析并讨论了裂纹参数（偏转角度和裂纹长度）及筋条布局对应力强度因子的影响。结果表明：随着裂纹偏转角度的增加,Ⅰ、Ⅱ和Ⅲ型应力强度因子最大值分别表现出不同的变化趋势（单调增加、无显著变化、先增加后减小）;裂纹长度同时影响应力强度因子最大值和裂纹类型;对于裂纹参数相同的九宫板,筋条布局改变了结构的模态振型,从而导致不同裂纹类型出现;特别地,当九宫板中央区域为正方形时,应力强度因子最大值和裂纹类型对裂纹偏转角度不敏感。     

A hybrid deep neural network based on multi-time window convolutional bidirectional LSTM for civil aircraft APU hazard identification

Safety is one of the important topics in the field of civil aviation. Auxiliary Power Unit(APU) is one of important components in aircraft, which provides electrical power and compressed air for aircraft. The hazards in APU are prone to cause economic losses and even casualties. So,actively identifying the hazards in APU before an accident occurs is necessary. In this paper, a Hybrid Deep Neural Network(HDNN) based on multi-time window convolutional neural network-Bidirectional Long Short-Term M...     

大气偏振光导航技术

为克服现有导航技术在战场应用中存在的不足,借鉴生物光学导航机理,开发新的导航方式,是未来导航技术研究的一个重要发展趋势。本文对自然界中的昆虫光学导航机理进行了介绍和分析,并对大气偏振光导航的发展趋势进行了探讨,提出了大气振光导航技术发展过程中需要解决的关键问题。     

基于数字滤波技术的飞参数据预处理

由于存在干扰,飞参系统记录的发动机参数中会存在噪声误差.为了利用数据对发动机工作状态和性能趋势进行监控,必须对数据进行预处理.本文利用动态数字滤波技术对高、低压转速数据进行预处理.处理后的数据更加连续、平滑,且更加清晰地反映出参数随时间的变化趋势,由此证明该方法是有效的.处理结果可在航空发动机状态监控中得到应用.     

计测仪器与模拟仿真技术

综述了计测仪器的技术特点、计测仪器与模拟仿真技术及其发展趋势。     

MQL切削的现状和发展

简介了MQL切削的现状及发展趋势。     

Review of cylinder block/valve plate interface in axial piston pumps: Theoretical models,experimental investigations,and optimal design

Axial piston pumps have been widely used in aircraft hydraulic systems to supply the system with pressurized fluid. The continuous improvement of the aircraft performance has put forward the demand on aviation piston pumps for high power density, safety, and reliability. The lubricating interfaces in axial piston machines are the key design issue that greatly determines the pump performance and service life. The cylinder block/valve plate interface is one of these critical lubricating interfaces and has received considerable attention from many researchers in the last half century. This study aims to review the state‐of‐the‐art literature on the cylinder block/valve plate interface comprehensively and systematically. First, we introduce various theoretical models developed to investigate the lubrication behaviors of the interface and compare them in terms of their assumptions and limitations. Second, the experimental studies on the cylinder block/valve plate interface are presented comprehensively, where the involved test rigs are divided into three types according to their fidelity levels and measurement functionality. Third, we summarize some typical approaches of structure optimization, surface shaping, and surface strengthening, which help improve the load-carrying and anti-wear capacities of the interface under severe operating conditions. Finally, the challenges and future trends of the cylinder block/valve plate interface research are discussed briefly.