湖南光电高清动中通卫星车系统

本文对湖南广电高清动中通卫星车系统进行了介绍说明,对湖南广电高清动中通卫星车系统中的动中通天线伺服控制系统、卫星通信系统、视频系统、音频系统、通话系统、集中控制系统与车体改造系统分别进行了说明;介绍了湖南广电高清动中通卫星车系统所采用的卫星通信体制、卫星链路计算结果及卫星测试结果;最后,本文介绍了动中通卫星车系统在广电领域进行高清电视实时移动转播中的应用前景。     

现代应急卫星通信系统应用综述

针对目前频繁出现大型灾难的救援工作,本文介绍了现代应急卫星通信系统的关键设备-动中通.介绍了目前国内动中通的四种方案-单脉冲体制的动中通、单脉冲辅以惯性器件的动中通、相控阵天线和纯惯导方案的动中通,并介绍了捷联惯导动中通的工作原理与特点.针对现代应急卫星通信系统,本文介绍了车载应急卫星通信系统、舰载应急卫星通信系统与机...     

“动中通”原理及应用

本文对“动中通”的原理和应用进行了说明,介绍了目前国内“动中通”的两种方案——单脉冲体制的“动中通”系统和采用惯导技术的“动中通”系统,并介绍了目前国内两种进口的低轮廓“动中通”系统——“相控阵天线”和“轮胎天线”;针对捷联惯导“动中通”系统,本文介绍了它的工作原理与特点;并对“动中通”卫星通信系统的网络设计进行了介绍;最后,本文介绍了“动中通”系统的应用前景。     

轮盘低循环疲劳试验器自动控制系统的开发

利用高速旋转试验设备进行轮盘低循环疲劳试验是开展轮盘疲劳寿命及损伤容限性能研究的有效手段。为确保此类试验器能够长时间稳定运行,开发了1套可靠的、无人值守的自动控制系统,以触摸屏为人机接口（HMI）完成试验参数的设置,以可编程逻辑控制器（PLC）为主站控制设备启停及转速循环,监测系统采用工控机（IPC）完成数据显示和保存,并采用第3方控件实现IPC和PLC的串口通信。测试结果表明：该控制系统稳定性高、可靠性好,完全满足设计要求     

基于PLC的潜油电泵机组试验测试系统

针对潜油电泵机组试验测试系统的现状，提出了应用可编程控制器（PLC）和PC组成集散控制系统，完成对电泵机组试验参数的数据采集和调节控制的设计方案，详细讲解了中心控制站和各个现场控制站的主要功能。应用表明系统性能稳定可靠、安装维护简捷，可以达到用户要求。     

PLC应用系统的可靠性问题研究

目的 提高PLC控制系统工程应用的可靠性。方法 逻辑分析与实证研究。结果 介绍了PLC控制系统中的主要干扰源，分析了PLC控制系统应用中的可靠性设计，最后给出了PLC控制系统主要采取的抗干扰措施。结论 研究PLC控制系统的可靠性，可以减少工业控制故障，提高经济效益。     

基于PLC的加输油控制阀测试装置控制系统的设计

简要介绍了某型飞机加输油控制阀测试系统工作原理和功能,设计了基于PLC的控制系统,给出了控制系统的硬件、软件设计和实现方法。     

"动中通"系统中极化角的计算

根据"动中通"卫星移动通信中极化角计算的情况,分析了极化角的产生机理,并详细推导了其计算公式.在"动中通"系统实际应用中,由于载体位置不断发生改变,极化角随之改变.本文进一步推导了极化角的补偿算法,为工程应用提供了理论参考,并且已经在"动中通"系统中取得较好的应用效果.     

基于PLC的PID控制方法在机械手调速控制系统的实现

针对实验室用机械手控制系统的调速要求,探讨一种基于PLC的PID控制的实现方法。通过采用对控制系统建立数学模型,并使用matlab/simulink仿真技术对系统性能进行分析,优化各项PID控制参数,应用PLC的PID功能指令实现对该系统的调速控制。     

用PLC取代原继电器控制系统的设计方法

本文分析了PLC控制系统与继电器控制系统比较具有的优势，在此基础上给出了用PLC取代继电器控制系统的方法。     

Satellite communication-a continuing revolution

SATCOM technology has revolutionized communications over the last 40 years. Initial SATCOM systems provided trunk telephony through large, fixed stations; current systems offer many services to smaller, fixed and mobile terminals. Personal Communications Systems, when fully implemented, will allow individuals to communicate with “anyone, anywhere, anytime,” and thus transform the world into a truly global village. New systems (currently being planned) will offer innovative services, such as computer networking and multimedia to the expanding mass market at an affordable cost. The rate of SATCOM progress shows no sign of slowing, and this revolution is expected to continue well into the future     

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     

Substorm timings and timescales: A new aspect

The magnetospheric substorm is a fundamental element of magnetospheric disturbances. After more than 40 years of intensive studies, various aspects of substorm morphology have been qualitatively established. Observations from the International Solar-Terrestrial Physics (ISTP) mission during the last decade have provided more detailed and complete pictures of substorms than before and, consequently, have provided new insights into substorm mechanisms. From the global auroral imaging it is shown that substorm onsets are locally confined; however, the effects of substorms involve a very large space at different times. Observations relying on in situ techniques can be misleading and can introduce confusion if not properly interpreted. On the other hand, remote sensing techniques such as global auroral imaging not only provide a robust means for studying substorm phenomenology but also yield relatively consistent results. This article reviews and summarizes a number of substorm studies conducted based primarily on global auroral images from NASA's Polar satellite, with a main focus on “quantitative” substorm morphology (i.e., onset timing, locations, energy input, and substorm timescales). These studies conclude that (1) auroral breakups are the most reliable substorm indicator, whereas other commonly used onset proxies may not always be associated with substorms and are subject to a propagation delay; (2) after breakup, the expanded auroral bulge can move either westward (60%) or eastward (40%); and (3) a typical substorm expansion phase lasts ～10 minutes and increases with increasing distances from the onset. A key conclusion from some recent studies seems to suggest that magnetotail reconnection, if it ever exists, is a consequence of substorm expansion onset. These findings provide constraints for substorm models and theories.     

Propagating Shocks

A survey of propagating interplanetary shocks reveals the following properties: (1) More shocks are observed around solar-activity maximum than minimum. (2) The maximum frequency of shock occurrence is between 2 and 5 AU. (3) Shocks slow down in the inner solar system, but in the outer solar system some may get a boost in speed when overtaken by a following shock. (4) The average shock strength (as measured by either the Mach number or the density ratio) also reaches peak values at distances of 2–5 AU. (5) Shocks are stronger at their noses than at their flanks. (6) At 1 AU, there are many more quasiperpendicular than quasiparallel shocks with the frequency of occurrence roughly constant with the cosine of the angle between the upstream field and the shock normal.     

PLC双行车全自动控制程序的设计

本文介绍了使用ＰＬＣ对两台车进行全自动控制的程序设计过程，重点 利用表格法驱动行车的方案和具体实现方法。     

水泥养护箱的远程智能控制系统

本文介绍了一种使用计算机和可编程控制器对水泥养护箱进行远程智能控制的系统 ,其管理部分采用工控机 ,控制部分采用OMRONPLC系统 ,二者通过RS - 4 2 2口进行串行通讯 ,同时介绍了系统的故障检测和报警功能     

柔性制造系统加盖机械手的PLC控制

柔性制造系统的加盖机械手是通过PLC控制程序来实现自动控制的。因此,PLC控制程序的设计就显得尤为重要。首先介绍了柔性制造系统的加盖机械手,进而编写了加盖机械手的控制程序,经实验验证,达到了预期的效果。     

Modeling of reliability and performance assessment of a dissimilar redundancy actuation system with failure monitoring

Actuation system is a vital system in an aircraft, providing the force necessary to move flight control surfaces. The system has a significant influence on the overall aircraft performance and its safety. In order to further increase already high reliability and safety, Airbus has imple-mented a dissimilar redundancy actuation system (DRAS) in its aircraft. The DRAS consists of a hydraulic actuation system (HAS) and an electro-hydrostatic actuation system (EHAS), in which the HAS utilizes a hydraulic source (HS) to move the control surface and the EHAS utilizes an elec-trical supply (ES) to provide the motion force. This paper focuses on the performance degradation processes and fault monitoring strategies of the DRAS, establishes its reliability model based on the generalized stochastic Petri nets (GSPN), and carries out a reliability assessment considering the fault monitoring coverage rate and the false alarm rate. The results indicate that the proposed reli-ability model of the DRAS, considering the fault monitoring, can express its fault logical relation and redundancy degradation process and identify potential safety hazards.     

The Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) on the New Horizons Mission

The Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) comprises the hardware and accompanying science investigation on the New Horizons spacecraft to measure pick-up ions from Pluto’s outgassing atmosphere. To the extent that Pluto retains its characteristics similar to those of a “heavy comet” as detected in stellar occultations since the early 1980s, these measurements will characterize the neutral atmosphere of Pluto while providing a consistency check on the atmospheric escape rate at the encounter epoch with that deduced from the atmospheric structure at lower altitudes by the ALICE, REX, and SWAP experiments on New Horizons. In addition, PEPSSI will characterize any extended ionosphere and solar wind interaction while also characterizing the energetic particle environment of Pluto, Charon, and their associated system. First proposed for development for the Pluto Express mission in September 1993, what became the PEPSSI instrument went through a number of development stages to meet the requirements of such an instrument for a mission to Pluto while minimizing the required spacecraft resources. The PEPSSI instrument provides for measurements of ions (with compositional information) and electrons from 10 s of keV to ～1 MeV in a 160°×12° fan-shaped beam in six sectors for 1.5 kg and ～2.5 W.