锆离子轰击Zr-4的腐蚀行为及其慢正电子谱研究

为了研究锆离子轰击对Zr-4合金锆耐蚀性的影响,用金属蒸汽真空弧(MEVVA)源对纯锆样品进行了1?015 至2?017 cm-2 的锆离子轰击,加速电压为50 kV。用X-射线光电子谱(XPS)对轰击表面各元素进行价态分析;用俄歇电子能谱(AES)分析氧化膜厚度。对轰击样品进行3次极化测量,以评价轰击样品在1N 硫酸溶液中的耐蚀性。利用慢正电子谱研究了轰击样品表面的缺陷情况。研究结果表明:除1×1015cm-2剂量外,轰击样品的耐蚀性都好于空白Zr-4,且5×1016 cm-2离子轰击样品的耐蚀性最好,轰击样品的自腐蚀电位大体上随着剂量的增加而下降。轰击Zr-4样品的腐蚀行为与其慢正电子谱之间存在着一定的对应关系。     

On the optimum plunger acceleration law in the slow shot phase of pressure die casting machines

The objective of this paper is to analyse a plunger acceleration law that is expected to minimize air entrapment in the slow shot phase of pressure die casting in horizontal cold chambers, and thus to reduce porosity in manufactured parts. The study is carried out using results from an analytical model of the flow of molten metal in the shot sleeve, which is based on the shallow-water approximation, and whose predicted optimum acceleration parameters are in good agreement with available experimental results. The results for the surface profiles of the wave formed during plunger movement using plunger acceleration laws which are typically used in pressure die casting are compared with those corresponding to the proposed law. Some analytical predictions for the wave profiles and for the mass of trapped air are compared with numerical results obtained from a finite-element code, which solves momentum and mass conservation equations. The limiting values of the initial filling fraction required for appropriate operating conditions are determined for wide ranges of acceleration parameters and pouring hole locations.     

慢扫速示波计时电位法同时测定合金中的铅与锌

采用慢扫速示波计时电位法同时测定铝合金中的铅与锌。该方法具有简便、快速,干扰小,选择性高等优点,特别适合于在其它离子共存条件下,测定合金样品中某种金属元素的含量。通过对铝合金样品中铅、锌测定,平均回收率和RSD分别为99.18%,99.00%和11%,16%。     

Slow-trap profiling of NO and N2O nitrided oxides grown on Si and SiC substrates

In this paper, we demonstrate the unique ability of a newly developed slow-trap profiling technique to characterise silicon-based MOS capacitors in strong inversion. We also demonstrate the applicability of the slow-trap profiling technique for the characterisation of oxides grown on SiC. The obtained slow-trap profiles show that NO nitridation eliminates while N₂O creates defects acting as slow traps in the case of both Si and SiC substrates. The corresponding effects of nitridation on interface traps and fixed oxide charge are also discussed.     

一种新型的非平稳随机系统参数辨识算法

本文针对带输入端慢时变干扰非平稳动态系统，基于理论推导提出新型的两步最小二乘算法，并对算法性质进行了详细的理论分析，数值仿真结果表明该算法的有效性和算法的一些重要性质。     

缓慢是不可能的——当代建筑中全球化理念、观念和速度的注解

作为悉尼基地的MGT建筑师事务所合伙人,理查德·弗兰西斯-琼斯相信,建筑文化的发展是通过辩论推进的,建筑师必须倾听并且参与这样的讨论与辩论从而更加理解建筑的内涵。这里提供了他相关的观点和分析。     

81枪簇气相缓蚀液态法防锈封存与包装研究

８１枪簇是部队装备较多的一种轻武器，其防锈封存与包装一直是部队仓库管理的难点，本文在实验的基础上，对８１枪簇气相缓冲蚀液态法防锈封存与包装作用机理，封存与包装工艺及其主要性能作了较详细的介绍，对部队基层仓库的枪械封存具有极大的指导作用。     

可伸缩TAGS

In a distributed Web server system where tasks are unpreemptible,the most important issue for improving quality of service(QoS)is how to realize fairness and reduce average slow down.In this paper we present an algorithm named Scalable TAGS by integrating Central Queue algorithm and Task Assignment by Guessing Size(TAGS),together with its performance analysis,system parameter setting algorithm subject to fairness require-ment,and optimal grouping method.     

慢中子正比计数器探测效率研究

推导出典型几何计数器中子探测效率及热能谱修正系数。~3He和BF_3计数器热中子探测效率实测值与理论预言值满意地符合。在E>0.1eV能区,仅考虑~3He(n,p)反应的理论值低于蒙特卡罗计算值[已计及(n,n)反应]和实验值,而实验数据与蒙特卡罗计算结果较好地符合。     

工程塑料管道焊接质量检测和性能评定方法

随着工程塑料管道应用的不断深入,管道的焊接质量检测及其性能评定成了一个重要的问题。介绍了工程塑料管道焊接接头的外观检测、内部缺陷的无损检测、焊接接头性能试验及快速裂纹扩展和慢速裂纹扩展方法等,这些对推动工程塑料管道的广泛使用具有重要的意义。