CAD技术的引深化发展

随着企业CAD技术的深入 ,设计中的数据管理、工艺等问题日益突出 ,采用PDM技术是CAD发展的必然趋势。     

变电站继电保护二次系统接地技术方案的设计探讨

随着国家经济的发展和信息时代的发展,电力系统的自动化建设地位日益提升,加强对电力系统稳定与安全的维护是十分必要的.鉴于此,本文主要分析变电站继电保护二次系统接地技术方案的设计.     

Quelques progrès récents dans le domaine des réseaux à paramètres répartis

Progress of distributed filters is very rapid. This paper shortly analyses the important methods of synthesis and approximation of microwave filters used until this day.     

变电运行中跳闸故障及处理技术

当前形势下,经济环境不断变化,电力系统的重要性正在日益凸显,而变电运行在电力系统中占据十分重要的位置。变电站运行的整体情况直接影响电力系统的运行效果,进而影响着人们的用电安全。目前,我国整体经济发展速度非常快,人们对资源的需求量与日俱增。因此,提高变电站的稳定性和安全性,已经成为电力系统工作的重点。基于此,结合具体实际,对变电运行的跳闸故障原因进行了深入的分析和研究,并提出了针对性的处理技术。     

浅论视频会议系统的运维保障

当前,基于各种专线网的远程视频会议系统的应用越来越普及,视频会议的运维保障成为各行业信息技术部门的重要工作内容,是一项新兴的专业技术管理工作。本文从视频会议系统运维保障的各个环节阐述了运维保障工作的内容和要求。     

数字电视整转中模拟用户管理系统到数字用户管理系统的过渡

有线电视的数字化转换是大势所趋,为进一步加快项城市有线电视数字化建设步伐,满足人民群众日益增长的精神文化需求,推动经济社会又好又快发展,项城市于2009年10月,搭建有线数字电视前端平台,开通有线数字电视信号;2010年6月正式开始整转,至2011年7月完成3万户的有线数字电视业务试点转换工作;2台操作机,每天办理整转300多户,如此高效,除了工作人员的辛勤努力,模拟用户管理系统和数字SMS管理系统的完美配合起了至关重要的作用。     

基于软交换平台的宽带电话业务的实现

在日趋激烈的电信市场竞争下，如何才能以快速、有效的接入方式为用户提供综合性业务是运营商最为关注的问题，随着软交换技术的日益成熟，宽带电话业务接入技术已成为业界普遍关注的一个重要课题，就软交换机技术及宽带电话的特点、组网方案及穿越防火墙技术进行了探讨。     

Reduction of lasing threshold current density by the lowering of valence band effective mass

In present day semiconductor lasers, there is a serious asymmetry between the very light conduction band mass and the very heavy valence band mass. Under laser threshold conditions, the hole occupation remains classical even while the electrons are degenerate. This results in a significant penalty in terms of threshold current density, carrier injection level, and excess Auger and other nonradiative recombination. We propose a combination of strain and quantum confinement to reduce the valence band effective mass and to lessen the laser threshold requirements.     

抗红外成像制导技术浅析

红外成像制导导弹自诞生以来 ,经过数十年的发展 ,技术日臻完善 ,应用日趋广泛 ,研究和探讨对抗红外成像制导的技术和方法就显得尤为重要。介绍了红外成像制导的基本原理、发展和在战争中的重要作用 ,重点探讨了对抗红外成像制导的几种技术手段。     

GNSS伪距单点定位及其实现──GNSS卫星导航定位方法之一

GNSS伪距单点定位,是一种较简易且非常实用的卫星导航定位方法,用户只需使用一台GNSS信号接收机,就能够全天候、全天时和全球性地测量运动载体的7维状态参数,本文简要地论述了GNSS伪距单点定位的基本原理及其实现。     

High‐Rate Continuous Synthesis of Nanocrystalline Perovskites and Metal Oxides in a Colliding Vapor Stream of Microdroplets

A high‐rate, continuous synthesis of functional nanomaterials using a home engineered reactor is reported. The reactor is able to produce low‐cost, kilogram‐scale BaTiO₃ nanopowders with a nanocrystalline particle size less than 30 nm at mild temperatures (<100 °C) and ambient pressure. Nebulization and collision of warm microdroplets (60–80 °C) of Ba(OH)₂ and Ti(O‐nBu)₄ very quickly result in total hydrolysis and subsequent conversion to BaTiO₃, yielding 1.3 kg/day of high purity, highly crystalline nanoparticles (25–30 nm). This synthesis procedure also enables high‐rate production of TiO₂ anatase (2.9 kg/day). It therefore provides a general platform for processing and scaling up of functional inorganic nanomaterials under very mild conditions.     

随机大气信道对激光信号传输影响的分析

首先介绍了激光信号通过随机大气信道时,大气中的气体分子和大气气溶胶离子、尘埃、雾、雨、霾等对激光信号的吸收和散射效应,造成了对激光信号的能量衰减,接着分析了大气湍流效应对光信号传输的影响,即光束的闪烁、弯曲、分裂.最后,对于不同大气条件下激光信号的传输进行了实验研究,给出了在同一时刻的不同天气条件、在同一天的不同时刻及不同能见度条件下的测试结果,并就实验现象进行了分析.所得到的结果很好地反映了理论分析,为大气通信提供了一定的指导.     

A New Method for the Demodulation of FM Signals

A novel time-domain semidigital approach for frequency demodulation is described. This conceptually simple method, utilizing a couple of engineering approximations, has excellent linearity for small frequency deviation, an undeteriorating sensitivity even for very small frequency deviation, is self-timed and is highly suitable for circuit integration; however, with the present day circuit technology, the usefulness of the method is limited to low frequency FM only.     

GPS: primary tool for time transfer

The Global Positioning System (GPS) is not only a navigation system, it is also a time-transfer system. As a time-transfer system it provides stability very close to one part in ten to the fourteenth over one day (1 ns/day). After a brief introduction to timekeeping terms, this paper reviews the role of GPS in time distribution and clock synchronization. The GPS coarse acquisition (C/A)-code single-frequency single-channel (one satellite) common-view (CV) time transfer is then discussed. Special consideration is given to progress in GPS C/A-code CV time and frequency transfer through the use of “all-in-view” multichannel receivers. This technique increases the number of daily observations by a factor of ten relative to conventional single-channel receivers and results in an improvement in time and frequency transfer stability by a factor of about three. Other important improvements discussed are the use of GPS carrier phase measurements and temperature-stabilized antennas. The latter reduce the daily and seasonal delay variations of GPS time-receiving equipment. The use of GLONASS as a complementary tool to GPS time transfer is also be reported. These improvements indicate that GPS, as a time-transfer system, should provide the capability to reach a stability of one part in ten to the sixteenth over one day (10 ps/day)     

甚低频横跨极区传播相位的观测与研究

对甚低频横跨极区传播相位观测数据进行了分析与研究,得出了甚低频跨极区传播相位的日、季变化的主要特征及规律:(1)在夏至前后的一段时间内,传播相位日变化往往呈现"驼峰"形状;(2)昼夜间的传播相位差季节变化明显;(3)传播相位的随机起伏大.     

Automated diagnostics for manufacturing machinery based on well-regularized deep neural networks

This paper presents a bigdata framework based on regularized deep neural networks for automated diagnostics for manufacturing machinery based on emitted sound, vibration, and magnetic field data. More precisely, we present SpotCheck, a prototype system that uses well-regularized deep neural networks to analyze sound, vibrational, and magnetic emissions of industrial machinery to provide noninvasive machine diagnostics, both for fault detection and to meter the day to day mode of operation of the machinery. It is completely automatic requiring no manual extraction of handcrafted features. It can operate with relatively small amounts of training data, but can take advantage of large volumes of unlabeled data when available, and scale to very large volumes of labeled or unlabeled data to improve performance as more data becomes available after deployment.     

Ultra-low drift microwave cryogenic oscillator

The operation of a microwave cryogenic sapphire resonator oscillator presenting an exceptional frequency stability for long integration times has been demonstrated. Based on a very simple design the 11.5 GHz oscillator presents a fractional frequency instability lower than 6/spl times/10/sup -14/ over one day.     

35KV开关柜内湿度分布监测及规律研究

35KV高压开关柜是电力系统非常重要的电气设备,因为其柜体密闭,常常造成柜内湿度富集和凝露,导致绝缘击穿甚至短路燃烧.本文针对下雨前、下雨天、雨后天晴接连三天的天气变化,采集并分析了实验数据,获得了三种天气条件下开关柜内湿度分布的规律.     

Diurnal distribution of rain attenuation in communication andbroadcasting satellite systems at 11.6 GHz in Italy

The paper presents long term probability distributions of rain attenuation exceeded in 0.5-h, 1-h, 2-h, 4-h, 8-h, 12-h and 24-h contiguous periods of the day, at 11.6 GHz, circular polarization, in satellite radio links, at two sites in Italy (Gera Lario and Fucino). These data can be useful to match the system design to the time of the day, which can be affected very differently by rain attenuation. The results can be scaled to higher frequencies and are directly applicable to actual satellite TV and radio broadcasting, and to telecommunication systems in the 12 GHz band. The data have been obtained by applying the synthetic storm technique (after testing its predictions in the 4-h case against experimental long term results) to a large and statistical reliable set of rain rate time series collected in five years (1978-1982) of continuous observation during the satellite SIRIO experiment, in slant paths of elevation angles 32° and 33°. The number of concurrent rain rate (and rain attenuation) time series considered is 587 for Gera Lario and 562 for Fucino, a very large data bank     

Method of Measuring Ultralow Water Vapor Permeation for OLED Displays

It is well known that proper encapsulation is crucial for the lifetime of organic LED (OLED) displays. With the development of better and better barrier coatings and perimeter seals, it has now become very desirable to be able to precisely measure the rate of water vapor and oxygen permeation through barrier coatings and perimeter sealing. This paper demonstrates a new permeation measurement method that uses tritium-containing water (HTO) as tracer materials. The theoretical detection limit is 2.4/spl times/10/sup -7/ g/(m/sup 2//spl middot/day).