α屏栅电离室谱仪系统的研制

介绍用于α放射性活度测量的平行板屏栅电离室谱仪系统.设计了一套带独立真空系统的屏栅电离室.该谱仪系统由三部分组成,电离室主体、充气系统及电子学系统.能量分辨率对于239Pu源可达25keV,在4～6MeV能区本底计数率为4h-1,探测效率接近50%.该谱仪系统可以测量核素的α射线能量,分析出它们的能谱结构,进而鉴定出各个α能谱所相应的核素及其相对含量和绝对含量.     

武钢金山店铁矿西副井通风机房进风口噪声治理

叙述了对空气动力噪声和机械噪声所采取的降噪措施以及其计算与构造 ,对采取降噪措施前后的声环境进行了实测     

破罡湖新站泵型方案的选择

文章介绍了破罡湖新站设计方案中,立式抽芯式轴流泵与常规的立式轴流泵方案比较及立式抽芯式轴流泵方案选择。     

A high-pressure MWPC detector for crystallography

The application of the Multi-Wire Proportional Counter (MWPC) as a potential detector for protein crystallography and other wide-angle diffraction experiments is presented. Electrostatic problems found with our large area MWPC when operated at high pressure are discussed. We suggest that a solution to these problems is to use a glass micro-strip detector in place of the wire frames. The characteristics of a high-pressure Micro-Strip Gas Chamber (MSGC) tested in the laboratory are presented.     

An ionization chamber with magnetic levitated electrodes

A new type of ionization chamber which has magnetically levitated electrodes has been developed. The electrodes are supplied voltages for the repelling of ions by a battery which is also levitated with the electrodes. The characteristics of this ionization chamber are investigated in this paper.     

热膨胀式断路器在发展

介绍国外热膨胀式断路器发展状况,特别介绍Alsthom公司为热膨胀式断路器研制出的最新灭弧室。     

富春江大坝船闸变形异常成因解析

监测资料表明,富春江左3闸墙段的上下游方向变位经常产生突变.通过定性和定量分析,对左3闸墙上下游方向变位异常进行了解析,发现主要是由于下游水位的日变化,以及每段闸墙结构状况不同和测点所处位置差异引起的,其上下游方向变位属于正常情况.     

Shape optimization of one‐chamber perforated plug/non‐plug mufflers by simulated annealing method

To economically and efficiently lower the venting noise, the development of a high‐quality muffler with compact volume has become crucial in the modern industrial field. The research work of shape optimization of straight silencers in conjunction with plug/non‐plug perforated ducts which may noticeably increase the acoustical performance is rarely addressed; therefore, the main purpose of this paper is not only to analyze the sound transmission loss (STL) of a one‐chamber plug/non‐plug perforated muffler but also to optimize the best design shape under a limited space. In this paper, on the basis of plane wave theory, the four‐pole system matrix in evaluating the acoustic performance is derived by using the decoupled numerical method. Moreover, a simulated annealing (SA) algorithm searching for the global optimum by imitating the softening process of metal has been adopted during the muffler's optimization. To assure SA's correctness, the STL's maximization of one‐chamber perforated plug mufflers at a targeted frequency of 500 Hz is exemplified first. Furthermore, a numerical case in dealing with a broadband noise emitted from a fan by using one‐chamber plug/non‐plug mufflers has been introduced and fully discussed. To achieve a better optimization in SA, various SA parameter sets of cooling rate and iteration parameter values were used. Before the SA operation can be carried out, the accuracy check of the mathematical models with respect to plug/non‐plug perforated mufflers has to be supported by experimental data. The optimal result in eliminating broadband noise reveals that the muffler with a plug acoustical mechanism has a better noise reduction than that of a non‐plug muffler. Consequently, the approach used for the optimal design of the noise elimination proposed in this study is certainly easy, economical, and quite effective. Copyright © 2007 John Wiley & Sons, Ltd.     

用于测量脉动气流平均流量的稳压箱的研究

以稳压箱为控制体建立基本方程对其无量纲化后进行数值求解，并用准则方程式予以拟合。计算结果表明，按本准则方程得到的曲与ＩＳＯ／ＴＲ３３１３中提供的实验数据的吻合程序优于该技术报告中的理论分析结果与实验数据的吻合程度。