Electrical resistivity of nickel-rich nickel-chromium alloys between 4 and 300 K

Electrical resistivity of Ni–Cr alloys containing 5.5, 11.3, 15.7, 16.8, 19.4, 22.0, 24.6, and 27.0 at % Cr has been measured as a function of the absolute temperatureT between 4 and 300 K. The sample with the Cr content of 22.0 at % exhibits a small minimum at about 10 K. No minimum has been observed in any other of the above samples, although an anomalousT dependence has been found in alloys containing 15.7, 16.8, and 19.4 at % Cr. The minimum has been discussed from the viewpoint of the Béal-Monod theory for the Kondo effect in concentrated systems and the mechanism by Greig and Rowlands based on aT-dependent decrease of the impurity electrical resistivity. It is concluded that the minimum in the Ni–Cr system is still a phenomenon which is not well understood at the present time.     

FPGA在某电视跟踪系统中的应用

介绍了一种以DSP为核心的数字式电视跟踪系统,主要研究了利用FPGA控制、处理数字视频信号的方法,实现了实时的视频叠加。详细讨论了FPGA的控制逻辑及其相关部分结构。采用FPGA实现视频显示信息的叠加,可有效减轻DSP的速度压力,提高系统性能。     

Observation and computer simulation of multicomponent chemical short-range order （MCSRO） for the bulk metallic glasses

The atomic configuration of chemical short-range order (CSRO) for the Zr-base metallic glasses was investigated by using nano-diffraction and high resolution transmission electronic microscopy (HRTEM) technology with a beam size of 0.5 rim. It is illustrated that the pattern of atomic configuration of CSRO might have various compound counterparts because of the chemical interaction of bonding atoms. Some atomic configuration of MCSRO is similar to the icosahedral structure with 10-fold symmetry of very weak spots. In deed, the nano-beam technology could clearly detect the evolution of atomic configuration in nanometer scale during the transformation from the metallic melt to the primary crystallization. The local atomic configuration of CSRO is also investigated by molecular dynamics simulation (MD) for the Zr2Ni compound in a wider temperature range. The CSRO in the melt could be pictorially demonstrated as distorted coordination polyhedron of the compound structure and/or the structure similar to cubo-octahedron analogs. The MD simulation illustrates that the atomic packing of long-range order disappears just above the melting point, but the chemical interaction of bonding atoms still exists that leads to form the various CSRO with the atomic configuration similar to stable or metastable unit cell of Zr2Ni compound. The icosahedral polyhedron became more abundance as the overheating temperature was raised.     

一种高效的视图维护算法

通过选择性算法将增量式视图维护和视图自维护有效地融合在一起．同时它还利用相关性算法对不相关更新进行过滤，可以有效地降低消息总数和数据的通信量，从而大大提高视图维护的效率，具有现实的应用意义．     

平面绕流泥沙磨损试验及水轮机磨损预估

本文介绍室内平面绕流磨损试验结果和应用于真机的磨损预估，与刘家峡、葛洲坝机组实测磨损量核算结果差别不大。在此基础上对在建的小浪底机组做了估算，并提出了一些看法。     

腐植酸造粒粘合剂的研究

给出了用不同粘合剂制备颗粒状腐植酸的试验结果。研究表明，腐植酸钠作为造粒的粘合剂，具有良好的综合指标。当其加入量为腐植酸含量的４％￣５％时，颗粒状腐植酸制成品抗冲击指数达到８２％以上，磨损指数低于８．８％。     

统一电力市场中兼具市场效率与经济公平的实现

南方电网中的五省(区)间差异巨大,为了建立统一的区域电力市场,在建立公平的交易机制和交易规则、促进自由竞争、提高市场效率的同时,必须考虑交易结果对区域内经济协调发展的影响。作者将关税理论应用于南方区域电力市场,结合各地区经济发展水平,提出了对自由竞争结果进行适度宏观调控的基本思路。算例分析表明,该思路是可行的。     

教室照明设计的几个问题

本文针对我国中小学学生视力低下率的状况,分析产生的原因,提出对建筑照明设计标准的建议及设计人员在中小学教室照明设计时需要注意的问题.     

高转速下薄壁转子不平衡质量计算

研究了高速旋转薄壁转子的不平衡质量的变化规律.将转子分成若干段,每个薄壁圆环按曲梁计算,进而提出一种由静止状态下不平衡质量推测高转速下不平衡质量的方法.此项研究对于高速运转薄壁转子的强迫振动研究具有重要意义,对确定静止状态下转子不平衡质量范围也有指导作用.     

采用图像格式的IDE硬盘直写记录

介绍一种采用IDE硬盘的高速图像记录系统的设计方法。该方法去掉了大量的软件编程代 之以硬盘直写图像文件的模式,将图像数据记录到硬盘的同时直接以文件形式存放。实验效果表明,采用该设计方法的记录设备做到了记录完全脱机,事后将硬盘通过USB接口直接与计算机相连,即可对图像进行访问,达到了预期的目的。