利用PLC实现动中通的集中控制

本文针对动中通的集中控制需求,设计了一种基于PLC 的控制系统,目的在于解决当前控制系统的可靠性不高、不便操控、性能不稳定等问题。介绍了以松下的FPX系列晶体管输出型的可编程控制器（PLC）为核心的动中通集中控制系统,详细描述了系统的硬件组成及软件结构,包括PLC 与人机界面（HMI）联机通信,实现人机对话,全方位管理和监控动中通系统的工作状态, 对出现的故障实时报警。     

Satellite inclination effects on UHF Satcom operation

The cause, magnitude, and time variance of satellite inclination are examined in light of the effects on military UHF SATCOM operation. The effects on required demodulator acquisition range, earth coverage footprint, and user terminal antenna pointing accuracy are considered. It is shown that the allowable satellite inclination to maximize on-orbit lifetime is not based on earth-terminal antenna pointing accuracy, but on allowable loss of high-latitude satellite coverage area. Worst-case Doppler shift for a UHF military satellite is 85-Hz uplink and 67-Hz downlink for a 5° SATCOM user elevation angle and 10° of satellite inclination. This amount of inclination is a reasonable allowance for station-keeping, to minimize thruster fuel and thus maximize satellite life. It is also shown that uplink Doppler frequency shift due to satellite inclination may be corrected based on satellite ephemeris data and rough user terminal location data     

Mobile Satellite Plans and Status

A variety of new communication functions will become available near the end of the decade when mobile satellite services (MSS) are introduced commercially in the United States and Canada. Mobile radios, hand carried radios and small fixed transponders will communicate directly through satellites into the telephone network or to private base stations. Voice, data, and position fixing services will be distance insensitive with good performance in difficult terrain and remote locations. Experiments with NASA satellites and studies in the U.S. and Canada demonstrated the technical feasibility and practical applications of mobile satellites. In 1983 Mobile Satellite Corporation, followed by Skylink Corporation, applied to the FCC for authorization to build and operate a land and aeronautical mobile satellite system for the United States. Canada had advanced its plans for an MSAT system. In response to these initiatives, the FCC issued a ``Notice of Proposed Rulemaking' that proposed the allocation of radio spectrum for the new service and asked for applications from prospective providers. Twelve applications were received. The shortage of radio spectrum in the U.S. has resulted in much contention over the proposed allocations, and the numerous applications have introduced competing systems concepts. The paper describes a likely system implementation, its services and markets, and the current regulatory status.     

Battlefield awareness via synergistic SAR and MTI exploitation

“Battlefield awareness” is critical to the success of future military operations. Existing and new sensor platforms will provide the necessary surveillance data; DARPA is developing the systems needed to turn the sensor data into meaningful information for the commanders. A central thrust of these efforts exploits the synergistic relationship between SAR and MTI radar. Used together, they offer comprehensive coverage of the battlefield     

Application of Ground/Air Data Link to General Aviation Operations

The Federal Aviation Administration (FAA) is currently upgrading secondary surveillance radars with systems which will have an integral data link capability, the Mode Select (Mode S) beacon system. These new systems will allow two-way data communications between ground systems (e.g., weather databases and Air Traffic Control (ATC) systems) and aircraft that are equipped with data link compatible Mode S transponders and suitable display and input devices. Initial data link services include both weather information and ATC advisories. The MITRE Corporation* is developing an in-house capability to perform end-to-end operational evaluation of data link services. Initially, a low-cost, portable pilot position man-machine interface is being developed for use in general aviation operations. The objective is to explore operational issues in laboratory and limited flight test environments, and to demonstrate these services on a data link I/O device, a laptop portable personal computer (PC) with touch panel. A group of pilots will bench test the interface design, and the results will be incorporated into the design used in flight testing. This paper describes the project's objectives and results to date, including implementation details and pilot test results.     

Integrated automatic vehicle location systems

The state-of-the-art transportation management system integrates automatic vehicle location, in-vehicle systems, customer information networks, and management information systems. As advanced technologies are integrated into transportation systems, the transit system becomes more efficient and reliable, which, in turn, makes it more attractive to users. The greatest benefit will not be realized until all of these technologies are integrated. Transit agencies and system integrators who take a total systems approach to the integration of advanced technologies will have a competitive advantage. They will provide services which provide the greatest utility to prospective users, riders, and the transit agency at the lowest cost     

ATM and FIS data link services

The Federal Aviation Administration (FAA) currently has under development data link services for Air Traffic Management (ATM), Flight Information Service (FIS), and communications, navigation, and surveillance (CNS). These services will be provided over the Aeronautical Telecommunications Network (ATN), a worldwide data network intended to provide data communications connectivity among mobile aircraft, airlines, and civil aviation authorities. The ATM and FIS services currently under development are part of an evolutionary process that will begin, for the most part, with duplication of voice services. In the future, services will facilitate a common source of data for pilots, controllers, and flight planners, as well as computer-to-computer communications between ground based and airborne automation systems. These future services will provide benefits such as the use of optimum aircraft tracks and flight profiles     

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.     

Current Issues and Future Trends: DVB-RCS Satellite Systems

The telecommunications market is reaching new types of customers who require their applications anywhere and anyway. Therefore, the DVB-RCS standard, which had great success in the fixed version is changing in this direction. The main objective of this work is to give an overview of architectures and technologies that can be used for implementation of a first-generation of advanced mobile satellite systems for the provision of broadband multimedia services.     

Ultra-reliable real-time control systems-future trends

Today's aircraft use ultra-reliable real-time controls for demanding functions such as Fly-By-Wire (FBW) flight control. Future aircraft, spacecraft and other vehicles will require greater use of these types of controls for functions that currently are allowed to fail, fail to degraded operation, or require human intervention in response to failure. Fully automated and autonomous functions will require ultra-reliable control. But ultra-reliable systems are very expensive to design and require large amounts of on-board equipment. This paper will discuss how the use of low-cost sensors with digital outputs, digitally commanded fault-tolerant actuation devices and interconnecting networks of low-cost data buses offer the promise of more affordable ultra-reliable systems. Specific technologies and concepts to be discussed include low-cost automotive and industrial data buses, “smart” actuation devices with integral fault masking capabilities, management of redundant sensors, and the fault detection and diagnosis of the data network. The advantages of integrating the control and distribution of electrical power with the control system will be illustrated. The design, installation, and upgrade flexibility benefits provided by an all-digital and shared network approach will be presented. The economic benefits of systems that can operate following failure and without immediate repair will be reviewed. The inherent ability of these redundant systems to provide effective built-in test and self-diagnostics capabilities will be described. The challenges associated with developing ultra-reliable software for these systems and the difficulties associated with exhaustive verification testing will be presented as will additional development hurdles that must be overcome     

关于直升机旋翼挥舞问题的探讨

本文研究直升机旋翼挥舞运动的变化规律和操纵规律,以桨叶挥舞运动的微分方程为模型,分析研究桨叶挥舞运动中旋翼拉力保持不变,且旋翼保持的挥舞状态,以及影响旋翼挥舞状态的因素。同时,直升机在悬停的基础上以前推杆为例,找出旋翼挥舞角的变化规律和旋翼锥体的倾斜方向变化规律,为分析旋翼挥舞中的实际飞行问题提供理论依据。     

Satellite communication system integrated into terrestrial ISDN

This paper presents an advanced satellite communication system named DYANET II. This system uses satellite channels as subscriber lines for ISDN customers as well as trunk circuits for overflow traffic. The system can offer the same ISDN services to satellite customers as those available to terrestrial subscribers in terms of numbering, signaling, and charging systems as well as user-network interfaces. It can also set up satellite channels on a demand assignment basis to achieve efficient satellite channel utilization, and to connect customers by single-hop satellite connections. A compact, lightweight Earth station has been developed for remote customers and temporary demands such as exhibitions.     

我院建成航空卫星通信实验地球站

在世界范围内实现新的通信、导航和监视／空中交通管理，能改善空中交通服务，减少运营费用和提高飞行安全等。中国民航学院建成航空卫星移动通信实验地球站，为研究新航行系统、试验自动相关监视等，创造了良好条件     

Where next for airborne AESA technology?

Airborne radar has evolved from early systems where almost all radar characteristics were fixed to today's highly flexible, software-driven systems. The most recent advance has been the widespread adoption of active electronically scanned array (AESA) antennas, which has given the system designer unprecendented control of antenna characteristics. However, in common with most conventional radars, even these systems only operate within a limited frequency band. This argues that the next major advance will be the advent of wideband and multi-band systems, thus addressing the major remaining constraint facing the system designer and offering the capability for a step change in the functionality and performance of future systems.     

大展弦比机翼试验随动加载系统研究

在飞机结构试验中,通常会遇到试验加载点随试验件变形而移动变化的问题,尤其是机翼大变形会导致加载点与翼面不垂直的问题。开发一种适用于全复合材料机翼试验的随动加载系统,该系统引入有限元分析方法将机翼变形划分成N个特征飞行点,采用飞行点随动加载来保证各级加载点与翼面的垂直度,实现垂直跟随加载;应用该加载系统进行大展弦比的机翼静力试验。结果表明:运用该加载系统可顺利实现该无人机机翼试验,且加载过程平稳,试验件无抖动,变形均匀,应变数据符合试验要求,可以为类似加载系统提供设计依据。     

Realization of an optimized wing camber by using formvariable flap structures

According to market research predictions, a large growth in the number of passengers as well as airfreight volume can be expected for the civil transport aircraft industry. This will lead to an increased competition between aircraft manufacturers. To stay competitive it will be essential to improve the efficiency of new generation of aircraft. Transonic wings of civil aircraft with their fixed geometry offer an especially large potential for improvement. Such fixed geometry wings are optimized for only one design point, characterized by the following parameters: altitude, mach number and aircraft weight. Since these vary permanently during the mission of the aircraft the wing geometry is rarely optimal. As aerodynamic investigations have shown, one possibility to compensate for this major disadvantage lies in the chordwise and spanwise differential variation of the wing camber for mission duration. This paper describes the design of a flexible flap system for an adaptive wing to be used in civil transport aircraft that allows both a chordwise as well as a spanwise differential camber variation during flight. Since both lower and upper skins are flexed by active ribs, the camber variation is achieved with a smooth contour and without any additional gaps. This approach for varying the wing's camber is designed to be used for replacement and enhancement of a given flap system. In addition, the kinematics of the rib structure allows for adaptation of the profile contour to different types of aerodynamic and geometric requirements.     

The DAVID mission of the Italian Space Agency (ASI - Agenzia Spaziale Italiana)

Italian satellite mission development history is dominated by the need to explore increasing frequency ranges and characterizing, through experimental results, communications channels, in order to render them useful for the design of operational systems using these frequency ranges. the DAVID (DAta and Video Interactive Distribution) Programme is a multi-experiment mission of the Italian Space Agency (ASI - Agenzia Spaziale Italiana). As the frequency range expands, today's frontiers will be in full use tomorrow; the series provides the status and main achievements of the program to date. DAVID will pioneer the use of the W-band (94 GHz channel) for telecommunications experiments that can contribute to the exploitation of that frequency range for future high-capacity operational services.     

Tethered dual spacecraft configuration: a solution to attitude control problems

A new dual spacecraft configuration comprising of two spacecraft halves judiciously connected through extremely short tethers is proposed. The simple tethered configuration induces stabilizing torques when subjected to attitude disturbances, thus ensuring 3-d pointing stability of both the satellite platforms. The enhanced system performance obtained using tethers enables a much greater flexibility in the choice of satellite mass distribution. Three particular TSS models involving parallel tethers, a `parachute-like' conical tether layout as well as a single tether connection have been considered. A detailed numerical response simulation shows that these modes of tether attachments bring about a radical change in the satellite attitude behavior from the nominal one involving relatively large librational amplitudes or instability to a virtually fixed desired orientation. Of these, the parachute configuration appears to be superior. The passive nature of the proposed mechanisms using tether lengths on the order of merely a couple of meters needed for small and medium size systems makes the concept particularly attractive for future space missions. Finally, it is felt that the proposed tethered dual satellite systems may offer a simple answer to three-axis attitude control problems.     

Aeronautical information and meteorological data-link services

Aeronautical Information and Meteorological Management is a key component of the International Civil Aviation Organization's (ICAO) global Air Traffic Management (ATM) operational concept. This global ATM concept is central to the Joint Planning and Development Office's (JPDO) Next Generation Air Transportation System (NGATS), and underlies Europe's Single European Sky ATM Research (SESAR) initiative. The availability of timely, accurate, and relevant aeronautical and meteorological information in the cockpit is critical for safe conduct of flight and forms the basis for Air Traffic Management (ATM) decision-making. The data-link of aeronautical and meteorological information will facilitate the creation of a common picture of the airspace situation for all flight crews, air traffic controllers, and airline operations personnel. Change notifications, timely warnings and alerts of threats to safe and efficient flight conduct will be enabled by these services. The ultimate goal is to provide access to on-line, real-time, quality information, and weather services to any aviation user, anytime, anywhere. In this framework, we present operational services and environment of the Aeronautical Information Management (AIM) and Meteorological (MET) data-link services envisaged to be implemented over the next decade in both Europe and the USA. It reflects concepts and system performance requirements currently developed by a joint EUROCAE (WG-76) / RTCA (SC-206) Committee. The envisaged AIM data-link services are presented: aeronautical updates both in textual and graphical fore, synchronization of aeronautical data between on-board and ground systems (exchange of permanent aeronautical data regardless of AIRAC cycles). The MET data-link services are also developed: weather planning, near-term, and reactive decision services.     

Achieving higher levels of electronic integration throughsystem-on-chip

All aerospace vehicles have the common constraint of limited space for the electronic systems. The challenge has always been how to pack effective electronic systems into the space available. Higher levels of electronic integration can give a competitive advantage; for example, by providing extra channels in a communications satellite thereby increasing revenue to the operator. Today's deep sub-micron manufacturing processes for integrated electronics offer an opportunity for a step change for electronic functionality that can be packaged in a given space. This technology makes possible, for the first time, a true system-on-chip approach to electronic systems, which is already being exploited by the commercial sector in products such as the mobile telephone