一个拼音汉字自动转换系统的设计与实现

给出了拼音汉字转换的定义，并建立了一个带调拼音词句到汉字语句的自动转换系统。它由五个部分组成，自动分词模块，词法分析模块，句法和语义分析模块，语义修饰模块和显示模块。其中句法分析是系统的核心，在比较各种方法的基础上选择了扩充转移网络模型，使ＡＴＮ的优点和音字转换的特点得到较好的结合，测试结果表明，系统的正确转换率达到９７％。     

基于C/S和B/S混合模式上机实验一体化系统的研究

基于C／S和B／S混合模式上机实验一体化系统的研究就是要解决当前上机教学中急需的计算机电子化管理的问题。该项目的完成除了对计算中心计算机基础课程上机实验适用以外，其它相关专业课程的上机教学和各种计算机课程综合训练等也同样适用，项目的完成对于提高上机实验环节的教学质量具有重要作用，因此具有实际意义。     

Performance of a simple Closed Aquatic Ecosystem (CAES) in space.

A simple Closed Aquatic Ecosystem (CAES) consisting of single-celled green algae (Chlorella pyrenoidosa, producer), a spiral snail (Bulinus australianus, consumer) and a data acquisition and control unit was flown on the Chinese Spacecraft SHENZHOU-II in January 2001 for 7 days. In order to study the effect of microgravity on the operation of CAES, a 1 g centrifuge reference group in space, a ground 1 g reference group and a ground 1 g centrifuge reference group (1.4 g group) were run concurrently. Real-time data about algae biomass (calculated from transmission light intensity), temperature, light and centrifugation of the CAES were logged at minute intervals. It was found that algae biomass of both the microgravity group and the ground 1 g-centrifuge reference group (1.4 g) fluctuated during the experiment, but the algae biomass of the 1 g centrifuge reference group in space and the ground 1 g reference group increased during the experiment. The results may be attributable to influences of microgravity and 1.4 g gravity on the algae and snails metabolisms. Microgravity is the main factor to affect the operation of CAES in space and the contribution of microgravity to the effect was also estimated. These data may be valuable for the establishment of a complex CELSS in the future.     

Interleaved boost converter with zero diode reverse-recovery loss

A three-phase interleaved continuous-inductor-current-mode (CICM) boost converter with zero diode reverse-recovery loss is proposed. In the converter, the di/dt of the output rectifiers is controlled by an integrated magnetic component. All the output rectifiers can be turned off softly and a very high efficiency is obtained. The equivalent-circuit model of the integrated inductors, the operation principle of the converter, and the design issues are discussed. Simulation and experimental results are presented.     

Physics of Substorm Growth Phase,Onset, and Dipolarization

A new scenario of substorm growth phase, onset and dipolarization during expansion phase and the corresponding physical processes are presented. During the growth phase, as a result of enhanced plasma convection, the plasma pressure and its gradient continue to be enhanced over the quiet-time values in the plasma sheet. Toward the late growth phase, a strong cross-tail current sheet is formed in the near-Earth plasma sheet region, where a local magnetic well is formed. The equatorial plasma beta (β _eq ) can reach a local maximum with value larger than 50 and the cross-tail current density can be enhanced to over 10nA/m² as obtained from 3D quasi-static magnetospheric equilibrium solutions for the growth phase. The most unstable kinetic ballooning instabilities (KBI) are expected to be located in the tailward side of the strong cross-tail current sheet region. The field lines in the most unstable KBI region map to the transition region between the region-l and region-2 currents in the ionosphere, which is consistent with the observed initial brightening location of the breakup arc in the intense proton precipitation region. The KBI explains the AMPTE/CCE observations that a low frequency instability with a wave period of 50–75 seconds is excited about 2–3 min prior to substorm onset and grows exponentially to a large amplitude at the onset of current disruption (or current reduction). At the onset of current disruption higher frequency instabilities are excited so that the plasma and electromagnetic field fluctuations form a strong turbulent state. Plasma transport takes place due to the strong turbulence to relax the ambient plasma pressure profile so that the plasma pressure and current density are reduced and the ambient magnetic field intensity increases by more than a factor of 2–3 in the high-β _eq region and the field line geometry recovers from tail-like to dipole-like – dipolarization.     

Near Earth Asteroid Rendezvous: Mission Overview

The Near Earth Asteroid Rendezvous (NEAR) mission launched successfully on February 17, 1996 aboard a Delta II-7925. NEAR will be the first mission to orbit an asteroid and will make the first comprehensive scientific measurements of an asteroid's surface composition, geology, physical properties, and internal structure. It will orbit the unusually large near-Earth asteroid 433 Eros for about one year, at a minimum altitude of about 15 km from the surface. NEAR will also make the first reconnaissance of a C-type asteroid during its flyby of the unusual main belt asteroid 253 Mathilde. The NEAR instrument payload is: a multispectral imager (MSI), a near infrared spectrometer (NIS), an X-ray/gamma ray spectrometer (XRS/GRS), a magnetometer (MAG), and a laser rangefinder (NLR), while a radio science investigation (RS) uses the coherent X-band transponder. NEAR will improve our understanding of planetary formation processes in the early solar system and clarify the relationships between asteroids and meteorites. The Mathilde flyby will occur on June 27, 1997, and the Eros rendezvous will take place during February 1999 through February 2000.     

基于以太网的飞机结构应变测试系统

基于我国飞机结构疲劳强度测试系统的实际情况,结合目前网络技术在工业领域中的应用,提出了一种基于以太网的远程控制型分布式应变测试系统,着重论述了采用以太网技术实现多个远程监控端和测试端之间的通信,通过实验验证了命令和数据传输的可靠性与实时性。     

基于位置信息的高分辨雷达角闪烁抑制方法

角闪烁误差是导引头寻的制导的主要误差来源,基于高分辨力雷达的单脉冲测角算法可有效改善角闪烁现象。现有的研究大多基于幅度加权的思想,利用距离单元的幅度信息进行加权平滑处理。本文在现有高分辨测角算法的基础上,结合高分辨一维距离像的位置信息,提出了一种新的角度信息处理方法。该算法充分利用了距离像有效单元的目标信息,提高了角度测量精度。仿真实验表明该算法对角闪烁有较好的抑制作用。     

面向质量的飞机制造过程BOM模型

飞机的质量保障能力与质量要求的矛盾日益突出,在其研制过程中迫切需要能够满足飞机产品质量信息传递的数字保障模型。本文依据质量的形成过程,以飞机的设计、工艺、制造步骤为主线,分析EBOM、PBOM到MBOM的转换过程,提出面向质量的飞机产品制造过程BOM模型。     

基于机器人柔性毛刷的空间翻滚目标消旋

设计了一种柔性减速刷消旋机构，将其安装于七自由度机械臂的末端，通过与翻滚目标帆板之间的接触碰撞进行消旋。利用绝对节点坐标法推导了柔性减速刷的动力学模型，并对其接触碰撞进行分析。针对自由漂浮空间机器人动力学建模和基座姿态的控制进行了研究，采用基于计算力矩法的滑模控制策略，对末端参数不确定的七自由度机械臂进行控制。滑模控制具有快速响应、对参数变化及扰动不灵敏等特点，确保了系统的全局鲁棒性和稳定性。有利于节省消旋时间，提高消旋效率。通过PD控制和滑模控制消旋仿真验证，该消旋策略能够成功消除初始旋转速度，消旋程度达90%以上，具有可行性与有效性。