Benchmarking of maintenance performance: a case study in two manufacturers of furniture

When profit margins of a plant are decreasing, the need forreliable and efficient maintenance policy becomes more important.Measuring maintenance performance is important for companiesto recognize whether their planned goals are achieved or not.Also, such measurements can be utilized for benchmarking, whichis one of the tools for never-ending improvement. But, theseobjectives cannot be achieved without well-documented data ofthe relevant variables. Better data coverage and quality isnecessary for following maintenance performance developmentand it would, in many cases, clarify the ambiguity concerningthe main problem in the context, namely that neither the productionnor maintenance department can show what effect maintenancehas on profitability. A more effective maintenance policy indirectly implies improvementsin product quality and manufacturing process effectiveness.Elongation of the production time, i.e. reducing the downtimedue to failures, planned replacements and repair, in additionto the improvement in the total maintenance activities, arealso some of the results that can be expected when an efficientmaintenance policy is used. Measuring and monitoring maintenanceperformance measures is required partly for detecting, and eventuallytreating as soon as possible, undesirable changes and partlyto make benchmarking with the best in the branch, which savesappreciable economic losses for companies. In this paper, a model for how to identify the measurable variables,which are needed to develop measures for monitoring maintenanceperformance behaviour systematically, is developed. Five maintenanceperformance measures are proposed and applied. An additionalmodel for systematically analysing the trend of maintenanceperformance measures, for an overall assessment of the company'ssituation, is presented. Two case studies in manufacturers offurniture are conducted to verify these models.     

Simultaneous feature selection and parameter optimisation using an artificial ant colony: case study of melting point prediction

Background  

We present a novel feature selection algorithm, Winnowing Artificial Ant Colony (WAAC), that performs simultaneous feature selection and model parameter optimisation for the development of predictive quantitative structure-property relationship (QSPR) models. The WAAC algorithm is an extension of the modified ant colony algorithm of Shen et al. (J Chem Inf Model 2005, 45: 1024–1029). We test the ability of the algorithm to develop a predictive partial least squares model for the Karthikeyan dataset (J Chem Inf Model 2005, 45: 581–590) of melting point values. We also test its ability to perform feature selection on a support vector machine model for the same dataset.     

Jump Type Cahn-Hilliard Equations with Fractional Noises

The authors explore a class of jump type Cahn-Hilliard equations with fractional noises. The jump component is described by a （pure jump） Lévy space-time white noise. A fixed point scheme is used to investigate the existence of a unique local mild solution under some appropriate assumptions on coefficients.     

用X光背景阴影成象法研究球靶消融内爆物理过程

使用X光背景照明诊断技术得到时间分幅。两维空间分辨消融型球靶内爆物理过程的信息,与解析模型比较推算出部分内爆过程动力学参量。在此基础上进一步讨论并建议使用双分幅X光背景照明诊断技术的可行性。     

高效率激光二极管泵浦100 Hz 3.5 J Nd：YAG MOPA激光器

研制了结构简单、高效率激光二极管泵浦Nd:YAG MOPA激光器.振荡级输出单脉冲能量1.13J,重复频率为100 HZ.MOPA系统输出最大单脉冲能量2.35 J,光-光转换效率为39％.实验结果和理论计算符合较好.     

对共轭双烯定向聚合活性较高的氯化稀土催化剂

本文提出的对共轭双烯定向聚合的稀土催化剂是由LnCl₃-R₃Al组成.它能引发丁二烯高顺式1,4定向聚合.但活性不高.本文研究了该二元体系添加醇类,提高它的催化活性而不损失其定向效应.我们发现催化活性依赖于催化组分比和加料顺序.对醇的活化作用进行了探讨,表明ROH先与LnCl₃形成一固定组成的醇合物(LnCl₃·3ROH)后,再与R₃Al组合而成活性催化剂.     

激光梯度场中荧光关联谱学的实验研究

研究了荧光关联谱(fluorescence correlation spectroscopy,简称FCS)在FCS测量中外加激光梯度场的影响.实验显示,微区内粒子的扩散时间随梯度场强度增加而增加,近似呈线性关系.同时,微区内平均粒子数目随梯度场相应地增加.粒子的极化率越大,相同条件下受到激光梯度场的影响就越大. 关键词： 荧光关联谱(FCS) 激光梯度场 扩散时间     

用肖特基电容电压特性数值模拟法确定调制掺杂Al_xGa_(1-x)N/GaN异质结中的极化电荷

研究发展了用肖特基电容 电压特性数值模拟确定调制掺杂AlxGa1 -xN GaN异质结中极化电荷的方法 .在调制掺杂的Al0 2 2 Ga0 78N GaN异质结上制备了Pt肖特基接触 ,并对其进行了C V测量 .采用三维费米模型对调制掺杂的Al0 2 2 Ga0 78N GaN异质结上肖特基接触的C V特性进行了数值模拟 ,分析了改变样品参数对C V特性的影响 .利用改变极化电荷、n AlGaN层掺杂浓度和肖特基势垒高度对C V曲线不同部分位置和形状影响不同 ,可以精确地求取极化电荷面密度 .通过模拟 ,得到Al0 2 2 Ga0 78N厚度为 45nm的调制掺杂Al0 2 2 Ga0 78N GaN异质结界面附近极化电荷面密度为 6 78× 10 1 2 cm- 2 .     

尿样中海洛因代谢物的检验

使用自制的固相微萃取装置,对尿液中海洛因代谢物6－单乙酰吗啡进行萃取,在装有衍生化试剂的密封玻璃瓶内顶空衍生,用GC－MS检测,取得了较好的效果。方法简便、快速,可用于吸毒者的确认。