Economic and economic-statistical design of a chi-square chart for CBM

In this paper, the economic and economic-statistical design of a χ² chart for a maintenance application is considered. The machine deterioration process is described by a three-state continuous time Markov chain. The machine state is unobservable, except for the failure state. To avoid costly failures, the system is monitored by a χ² chart. The observation process stochastically related to the machine condition is assumed to be multivariate, normally distributed. When the chart signals, full inspection is performed to determine the actual machine condition. The system can be preventively replaced at a sampling epoch and must be replaced upon failure; preventive replacement costs less than failure replacement. The objective is to find the optimal control chart parameters that minimize the long-run average maintenance cost per unit time. For the economic-statistical design, an additional constraint guaranteeing the occurrence of the true alarm signal on the chart before failure with given probability is considered. For both designs, the objective function is derived using renewal theory.     

Profile monitoring of reflow process using approximations of mixture second‐order polynomials

Lately, profile monitoring has received considerable attention in the statistical process control research field. This paper proposes a novel monitoring framework for the reflow process data, which uses two goodness‐of‐fit criteria to select the change points in the mixture polynomial model. Among change points, the mixture second‐order polynomials are utilized to piecewisely approximate the nonlinear profile data of the reflow process. The well‐known Hotelling T² and proposed EWMA₄ control charts are then employed to monitor the parameter estimates. The experimental results demonstrate that the proposed monitoring framework presents better performances in detecting outlying profiles than the conventional methods in phase I. In phase II, the performance of the proposed framework is assessed in terms of the out‐of‐control average run length. Copyright © 2014 John Wiley & Sons, Ltd.     

双功能偶联剂SPC的一种新合成方法及其碘标记

放射性碘标记药物广泛用于医学检验及临床诊断和治疗中。放射性碘标记蛋白质不管是采用Ch-T、Iodogen直接标记方法还是采用Bolton-Hunter试剂间接标记方法,其存在的主要问题是标记物可能在体内严重脱碘[1,2]。为了克服这一问题,人们不断改进碘标记方法。其中,Zalutsky、W ilbur     

电网在三种边攻击方式下的级联失效

研究美国西部电网在三种边攻击方式下级联失效差异性.定义边ij的初始负载为(k_ik_j)^θ,k_i,k_j分别表示节点i和j的度,θ为一可调参数.三种边攻击方式分别为:最小负载边攻击方式(LL)、最大负载边攻击方式(HL)和容量比最小边攻击方式(SPC).通过分析电网的拓扑结构,研究三种攻击方式级联失效差异性.研究表明:HL和LL攻击方式下,受攻击边的范围不随θ而改变,HL的攻击效果随θ的增大而增强,LL的攻击效果随θ的增大而减弱.而SPC法选中的被攻击边随θ变化,当θ取值较小时,SPC攻击边是拓扑结构较特殊的一种最小负载边,随着θ的增大,SPC攻击边趋向于高负载边,因此θ较小时,SPC的攻击效果和LL接近,当θ较大时,SPC的攻击效果和HL接近.     

利用谱共轭技术补偿光纤传输信号的失真

分析了谱共轭技术用于补偿光纤色散和非线性的基本原理。通过对超高斯脉冲的数值计算表明，谱共轭技术（SPC）较时域相位共轭技术（TPC）能更好地恢复波形失真。为了弥补SPC不能补偿脉冲内拉曼散射的缺点，提出将SPC和TPC结合使用的方法。将其作用于光孤子串脉冲，不仅进一步优化了整形效果，而且还能有效抑制孤子自频移。     

GARCH型过程相关控制图

将 GARCH模型引入到自相关质量过程控制图中 ,提出了 GARCH型控制图 ,为方差随时间变化的过程提供了处理工具 ,可以解决实际工作中因设备、原材料或操作因素使质量波动水平发生变化的控制问题     

Enzymatically modified Soy Protein

Optimum temperature and pH for the isolation of soy protein isolate (SPI) from soy protein concentrate (SPC) were established. Enzymatic hydrolysis of SPI with enzymes of different specificities such as trypsin, chymotrypsin, papain and urease was carried out and the products of hydrolysis were characterized by molecular mass determination [sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)] and thermal techniques [differential scanning calorimetry (DSC) and thermogravimetric analysis (TG)]. Enzymatic hydrolysis resulted in a significant reduction in molecular masses. However the thermal stability of hydrolysed SPI was similar to native SPI indicating that it is independent of molecular mass. DSC studies indicated an increase in temperatures of endothermic transition associated with SPI denaturation and loss of absorbed moisture in samples of lower molecular masses. This revised version was published online in August 2006 with corrections to the Cover Date.     

Evaluating use of ferricyanide-mediated respiration bioassays to quantify stimulatory and inhibitory effects on Escherichia coli populations

A number of recent studies have utilised ferricyanide as a respiratory mediator for microbial-based assays for determining water quality parameters such as biochemical oxygen demand (BOD) and toxicity. The majority of assays published to date obtain a result by determining the difference in ferrocyanide accumulation between a test sample and one or more control samples. However, a validation of the relationship between ferrocyanide accumulation and standard measures of cell density or viability has not yet been performed. To this end, a rapid microbially catalysed ferricyanide-mediated respiration (FM-RES) assay was compared with standard plate count (SPC) and spectrophotometer (OD₆₀₀) measurements on a growing batch culture of Escherichia coli. Good agreement was observed between all techniques, with predictable deviations noted in different phases of the growth curves. Standardised FM-RES assays showed excellent correlations with the SPC method under controlled conditions, indicating that short-term changes in microbial activity are due to a change in per-cell respiration, rather than changes in cell numbers. The FM-RES assay was then used to observe the changes in the respiration of E. coli induced by the addition of a glucose-glutamic acid (GGA) mixture, 3,5-dichlorophenol (3,5-DCP) and Ag⁺ in various combinations and concentrations. Stimulation of respiration was pronounced in the presence of GGA while both 3,5-DCP and, in particular, Ag⁺ demonstrated inhibitory respiratory effects. The results highlight the validity and suitability of ferricyanide-mediated respiration bioassays, with appropriate modification, to monitor either stimulatory effects on microbial populations, such as occurs with BOD, or inhibitory effects, such as occurs with toxicity assays.     

固定时间域可变采样间隔的统计控制图

本文从提高统计控制图对过程波动检测能力和方便管理的角度出发 ,对可变采样间隔(VSI)控制图进行改进 ,提出了针对连续过程质量控制应用需要的固定时间域可变采样间隔(VSIFT)控制图。文章详细介绍了VSIFT均值极差控制图、VSIFTEWMA控制图的设计 ,并分别评价了它们对过程异常状态的检测能力     

高能量短脉冲激光作用水分子的动力学模拟

基于高能量短脉冲激光作用水分子实验的复杂性,需用采取一种比较准确且较为方便的方法来预测实验结果是必要的.本文采用分子动力学方法(Molecular Dynamics)对高能量密度短脉冲激光加载下的超临界水分子进行热力学分析及结构研究.结果表明,随着能量快速加入加载区域,水分子系统的温度迅速提高.同时,由于分子迅速向四周扩散,在加载区域产生空泡.其中,只有25.5%的能量用以提高水分子系统的动能(温度),其余的能量都用于增大水分子系统的势能(水分子间距).伴随着温度的提高,水分子热运动加快,有序程度逐渐减弱,O—H间距增加,水分子间的氢键作用减弱,分子极性降低.分子动力学模拟方法研究短脉冲高能量激光对水分子的作用,对水下激光微加工研究有一定指导意义.