Development of the critical film thickness correlation for an advanced annular film mechanistic dryout model applicable to MARS code

It is generally assumed in the mechanistic film dryout model that the critical heat flux (CHF) arises when liquid film calculated from evaporation, droplet entrainment and deposition gets dryout. The dryout of film is usually assumed when film thickness becomes zero. However, it was indicated that the complete dryout assumption can estimate CHF well for uniform heating case but cannot simulate accurately for non-uniform heating case. The critical film thickness concept may be an appropriate approach physically because there is a possibility of instantaneous disappearance of liquid film when it gets very thin. Therefore, a critical dryout film thickness correlation was developed to properly model dryout phenomenon together with MARS code based on experimental data. The modified version of MARS implementing a newly developed critical dryout film thickness correlation was assessed using various dryout data including those of non-uniform heating case and flow reduction transient test. The prediction results showed improved agreement with the experimental data.     

堆泵浦3He-Ar-Xe激光体系小信号增益与效率实验研究

介绍了CFBR-Ⅱ堆泵浦3He-Ar-Xe体系1.73μm波长激光小信号增益和泵浦效率的实验研究.在脉冲峰热中子注量率为6.9×1014cm-2.s-1、3He、Ar、Xe气体的比例为80.219.30.5,总压强为8.3×104Pa时,采用透射率从1.7%到10%的6个谐振腔输出镜均获得了激光输出.在谐振腔输出镜透射率为7%时,得到了激光脉冲峰功率为45mW,其对应的激光泵浦效率为1%.在此基础上,利用Rigroa分析方法拟合出3He-Ar-Xe体系激光的小信号增益为0.24%/cm,饱和光强为36W/cm2.     

500kV变电所保护小室设计及抗干扰措施

随着计算机软硬件技术、网络技术，通信技术的发展，计算机监控系统在500kV变电所中已广泛应用。在一些工程中，为减少控制电缆，缩减主建筑占地面积，二次设备采用了放至配电装置区的方式。由于弱电设备多，环境电压等级高，电磁干扰强，使许多人对这种方式的安全可靠性提出了疑问。本文着重从干扰源、抗干扰措施及保护小室的设计角度作了分析，对保护小室下放模式的安全可靠性作出肯定，并对小室屏蔽设计提出了一些看法。     

Microstructures of laser cladding of intermetallic-ceramic composite coatings

The microstructures of laser cladding of (Ni-24.5%(atom fraction)Al)+5O%(mass haction)WC coatingsbefore and after aging was comparetively studied by using SEM and TEM. It is shown that dissolving of WC and reprecipitating in the forms of WC and W,Coccurred during laser cladding, and intermetallic γ' (Ni3Al) orderly precipitatefrom metastable supersaturant Ni-matrix solid solution after heat treatment. The structures are favorable for coating'sproperties.     

A flexible and recoverable client/server database event notification system

A software architecture is presented that allows client application programs to interact with a DBMS server in a flexible and powerful way, using either direct, volatile messages, or messages sent via recoverable queues. Normal requests from clients to the server and replies from the server to clients can be transmitted using direct or recoverable messages. In addition, an application event notification mechanism is provided, whereby client applications running anywhere on the network can register for events, and when those events are raised, the clients are notified. A novel parameter passing mechanism allows a set of tuples to be included in an event notification. The event mechanism is particularly useful in an active DBMS, where events can be raised by triggers to signal running application programs. Received July 21, 1995 / Accepted May 30, 1996     

交换机LS中继全自动维护的实现

环路启动(LS)中继在电力专网中使用非常广泛,人工恢复长时间不拆线的LS中继的维护方式已经不能满足需求,故利用开发工具(Delphi)编写软件实现和交换机通信,自动检测所有LS中继线的状态,自动恢复长时间处于维护忙状态的LS中继。文章介绍了该系统的实现过程及系统中各模块的功能。该系统的实现提高了工作效率,保障了交换网的通信质量。     

基于小波变换的超声电机启动和关断特性的测试与分析

叙述了本研究中心研发的超声电机瞬态测试系统及其测试方法。由于噪声的影响，启动、关断响应曲线常常不太光滑，以往采用平滑技术和数字滤波等处理办法，获得启动和关断响应特性精度较差。本文利用小波变换对原始启动、关断响应数据进行分析，去除噪声，从而较准确地获得了超声电机启动和关断的响应时间。实验结果表明，超声电机确实具有毫秒级的响应时间。     

解决瓶颈问题提高精整能力

本文根据济钢中厚板厂精整生产线的设备能力，分析了双边剪、成品检查台、垛板台收集钢板存在的问题是精整乃至中厚板厂生产的“瓶颈”，并提出提高精整能力的途径。     

高压输电线路铁塔选型漫谈

本文结合近几年来,我国高压输电线路铁塔选型方面的基本情况,和作者本人从事高压输电线路铁塔结构设计中的一些经验和看法,简述了大负荷、新结构的塔型使用现状和铁塔选型应注意的一些问题。     

Ultra-precision lapping of machinable ceramic Si3N4-BN by in-process electrolytic dressing

The machinable ceramic Si₃N₄-BN is a material which is increasingly being employed for automobile bearings and machinable ceramics. This material is very hard and has high resistance against volatile temperature and wear. It's efficient quality and accurate surfaces have always been of high demand for many applications in the industrial field. Besides, this material is varied by the percentage of BN contained in it, and the characteristics of lapping also varies according to this percentage of BN. Hence, in-process electrolytic dressing for ultra-precision lapping was introduced and used to experiment with the differing BN percentages in machinable ceramic Si₃ N₄. Metal-bonded super-abrasive diamond lapping wheels have superior qualities such as high bond strength, high stability and high machinability. The major problems encountered are wheel loading and glazing, which impedes the effectiveness of the cast-iron bonded diamond lapping wheel and, therefore, dressing should be considered. In this respect, in-process electrolytic dressing (IED) is proposed as an effective method regarding continuous protruding abrasives on the surface of wheels, whereby loading and glazing phenomena can apparently disappear. In this paper, the machining characteristics of machinable ceramic Si₃N₄-BN have been studied by adapting the IED lapping process in terms of the percentage of h-BN material.