On mappings of bounded variation

We present the properties of mappings of bounded variation defined on a subset of the real line with values in metric and normed spaces and show that major aspects of the theory of realvalued functions of bounded variation remains valid in this case. In particular, we prove the structure theorem and obtain the continuity properties of these mappings as well as jump formulas for the variation. We establish the existence of Lipschitz continuous geodesic paths and prove an analog of the well-known Helly selection principle. For normed space-valued smooth mappings we obtain the usual integral formula for the variation without the completeness assumption on the space of values. As an application of our theory we show that compact set-valued mappings (=multifunctions) of bounded variation admit regular selections of bounded variation. Partially supported by the Russian Foundation for Fundamental Research, Grant No. 96-01-00278.     

基于DSP的便携式多功能电能测量仪的应用研究

介绍了DSP技术在电力测量中的应用，经A/D采样后的电流，电压送入DSP芯片，并进行相关处理。得到所需的电流和电压的平均值。有功功率及功率因数等电力参数。本系统还可以通过通信模块进行远程测量和数据传输。该方法具有灵活，可升级和高效的特点。     

苏里格气田水平井随钻地质导向技术及应用

确保水平井轨迹顺畅、提高储层钻遇率和实施效果已成为水平井开发的技术难点。以苏54区块所实施水平井为例,通过对水平井实施情况进行分析,结合苏里格气田基本地质特征,从水平段地质模型及地质导向等关键环节入手,总结出了适合苏里格气田水平井开发相关随钻地质导向配套技术。通过现场应用,效果明显,也为同类气藏水平井随钻地质导向提供了有益借鉴和指导作用。     

54/5位直流数字电压表的设计

介绍了高精度、高分辨率数字电压表的一种设计方法,可作数字万用表或精密测量仪器的表头,供设计者参考。     

加工中心编程、操作存在的问题与对策

在数控机床普及推广应用中,常常因操作或编程失误,造成撞毁刀具,损坏工件、出现废品、发生机械事故,给操作者带来了很大的心理压力。通过在数控加工中心的实践教学中的体会,对G54Z坐标的设置,对刀过程操作、设置刀具号与刀具库号,刀具号与刀具补偿号、刀具补偿号与刀具补偿值、刀补方向与刀具路径方向、编程小数点书写、程序输入等常易出现的问题,提出了防范措施。     

Extraction of zinc from ammoniacal/ammonium sulphate solutions by LIX 54

The extraction of zinc from ammoniacal/ammonium sulphate aqueous media using LIX 54 has been studied. The metal extraction rate has been examined and also the effect of temperature on the extraction of zinc (ΔH° = −8·8 kJ mol⁻¹). The effect of the aqueous pH, and therefore zinc ammine complex formation, on the extraction of zinc was studied. Stripping of the metal from loaded organic phases was carried out at various rates, temperatures (ΔH° = 3·2 kJ mol⁻¹) and sulphuric acid concentrations. The results obtained were compared with others obtained from the literature wherein different extractants were used. © 1998 SCI.     

Recovery of copper from ammoniacal/ammonium sulfate medium by LIX 54

The extraction‐stripping reaction of Cu(II) by LIX 54 in Iberfluid from aqueous ammonium sulfate medium at pH 8.5 has been investigated. The effects of pH, metal ion, extractant concentration as well as the loading capacity of the reagent were studied. The extraction equilibrium constant for copper was determined numerically to be 7 × 10⁻⁷. Experimental data can be explained assuming the formation of CuR₂ species in the organic phase (R represents the extractant). Copper stripping was studied using typical spent copper electrowinning solutions as stripping medium. The number of stages required for the extraction and stripping of copper was also evaluated. The results were used to asses the conditions for purification of industrial waste solutions (eg spent etchants) containing copper through counter‐current extraction‐stripping. © 1999 Society of Chemical Industry     

含硫-铝钢GS35C-A硫化钙夹杂热力学分析和工艺改进

针对试验GS35C-A钢（/%:0.34～0.35C,0.20～0.22Si,0.69Mn,0.013～0.016P,0.026～0.045S,0.027～0.046A1,0.000 8～0.001 9Ca）夹杂物变性进行了热力学计算,并对工艺1[BOF-LF（硫合金化）-RH-钙处理-CC]和优化工艺2[BOF-LF-RH-钙处理-硫合金化-CC]对应的钢中夹杂物形貌及数量进行了研究。结果表明:（1）随着钢液中[S]的升高,生成CaS所需的平衡钙含量降低,钙处理变性生成低熔点夹杂物时钢液中的[Al]逐渐降低;（2）优化工艺2后RH离站Ca、S含量分别从优化前（工艺1）的0.001 9%和0.045%降至0.000 8%和0.026%,平均连浇炉数由原2.5炉提高至8炉;（3）优化前（工艺1）中间包典型夹杂物组分为硫化钙包裹的镁铝尖晶石,优化后（工艺2）中间包夹杂物为铝酸钙;RH离站、中间包钢中每mm²夹杂物个数分别从优化前9.09和6.23降至5.06和3.76。     

基于TMS320C54x的机内测试测试性验证系统

通过故障注入的方式检测测试系统的性能是一种有效的验证系统测试性水平的方法．本文提出了一种基于TMS320C54x的机内测试（Built-in Test,BIT）测试性验证系统的设计方案,给出了系统实现的基本原理以及总体结构框图、工作流程图、原理图等设计．故障注入系统是BIT测试性验证系统的核心部分,经试验证明采用基于TMS320C54x将测试性验证系统以平台化方式实现的设计,能够满足验证BIT测试性的要求,并有效地降低了设计复杂度,达到了预期的设计目的．     

EK1决议选译

德国GS标志是德语"经检测安全"的缩写,表示产品通过德国认证机构的型式检测和批量生产监督.该标志是一个包括电气产品在内的通用产品安全认证标志.GS认证属于自愿性认证.