A new variable control chart under failure‐censored reliability tests for Weibull distribution

In this paper, we propose a new variable control chart under type II or failure‐censored reliability tests by assuming that the lifetime of a part follows the Weibull distribution with fixed and stable shape parameter. The purpose is to monitor the mean and the variance of a Weibull process. In fact, the mean and the variance are related to the scale parameter. The necessary measures are given to calculate the average run length (ARL) for in‐control and shifted processes. The tables of ARLs are presented for various shift constants and specified parameters. A simulation study is given to show the performance of the proposed control chart. The efficiency of the proposed control chart is compared with a control chart based on the conditional expected value under type II censoring. An example is also given for the illustration purpose.     

Super‐resolution mapping of the waterline from remotely sensed data

Methods for mapping the waterline at a subpixel scale from a soft image classification of remotely sensed data are evaluated. Unlike approaches based on hard classification, these methods allow the waterline to run through rather than between image pixels and so have the potential to derive accurate and realistic representations of the waterline from imagery with relatively large pixels. The most accurate predictions of waterline location were made from a geostatistical approach applied to the output of a soft classification (RMSE = 2.25 m) which satisfied the standards for mapping at 1 : 5000 scale from imagery with a 20 m spatial resolution.     

Realisation of grounded capacitor with operational amplifiers and resistance

A simple circuit is given for the simulation of a high-quality grounded capacitor. It uses only two operational amplifiers and one resistance. Experimental results are included.     

A new method for monitoring micro-electric discharge machining processes

Micro-electric discharge machining (μ-EDM) is a very complex phenomenon in terms of its material removal characteristics since it is affected by many complications such as adhesion, short-circuiting and cavitations. This paper presents a new method for monitoring μ-EDM processes by counting discharge pulses and it presents a fundamental study of a prognosis approach for calculating the total energy of discharge pulses. For different machining types (shape-up and flat-head) and machining conditions (mandrel rotation and tool electrode vibration), the results obtained using this new monitoring method with the prognosis approach show good agreement between the discharge pulses number and the total energy of discharge pulses to the material removal and tool electrode wear characteristic in μ-EDM processes. On applying tool electrode vibration, the machining time becomes shorter, because it removes adhesion. The effect of tool electrode vibration in order to remove adhesion can be monitored with good results. In order to achieve high accuracy, the tool wear compensation factor has been successfully calculated, since the amount of tool electrode wear is different in each machining type and condition. Consequently, a deeper understanding of the μ-EDM process has been achieved.     

引发剂用量对聚联苯胺结构及性能的影响

采用界面聚合法于室温不同单体与引发剂摩尔比条件下合成了聚联苯胺。利用红外光谱(FTIR)、紫外可见吸收光谱(UV-vis)、透射电镜(TEM)、X射线粉末衍射(XRD)、循环伏安(cyclic voltammogram)等方法初步探讨了引发剂用量对聚联苯胺形貌、结构和性能的影响。结果表明,采用界面聚合法合成的聚联苯胺均呈现微米级棒状形貌,且分布均匀、表面光滑,引发剂用量对聚合物形貌没有明显影响;通过结构分析及循环伏安测试可知,当n(单体)∶n(引发剂)=1∶1时,聚联苯胺的共轭程度、分子链排列规整性及电化学活性最佳。     

SUBJECTS INDEX

Exponentially weighted moving average (EWMA) control charts are very widely used for the detection of small shifts. Another similar charting structure is double EWMA (DEWMA) control chart for the improved detection of the shifts. Many interesting features of EWMA and DEWMA have been described in the literature. This study intends to investigate EWMA and DEWMA control charts under Type-I censoring for gamma-distributed lifetimes. The idea of conditional expected values is used to monitor the mean level. The performance evaluations are carried out using average run length as a measure in this study. The optimum sample size comparisons for the specified and unspecified parameter are also part of the study. To assess the overall performance of the control charts, we also used extra quadratic loss and it is found DEWMA is an efficient chart for the detection of shift in scale parameter. Moreover, an illustrative example for practical considerations is included in the study. It is observed that varying censoring rates affect the performance of the chart depending upon the type of chart, the method of estimation, and the amount of shift.     

嵌段共聚物为模板合成纳米结构导电聚合物材料研究进展

简述了以嵌段共聚物为模板合成纳米结构导电聚合物材料的国内外发展状况。近年来,纳米结构导电聚合物材料作为极具研究价值的新型功能材料而成为了材料科学的研究热点。以嵌段共聚物为模板则是制备此类材料最有前途的方法之一。本文详细地总结并归纳了通过该方法制备形貌规整的纳米级导电聚合物材料的成形机理、实验方法及其影响因素等。最后总结了纳米结构导电聚合物材料相关研究中存在的诸多问题,并简要指出以嵌段共聚物为模板有助于提高导电高聚物的形貌及尺寸的可控性,进而有助于改善导电高聚物的溶解性、加工性能、电导率等各项性能,也将有利于拓宽导电高聚物在纳米科技领域中的应用前景。     

Precision machining by discharge pulse counting methods in micro EDM processes

Due to the occurrences of debris, the ability of micro-EDM to produce precise dimension is degraded, hence positioning display indicator of micro-EDM machine is not accurately measure the real dimension. Therefore, imprecise workpiece dimension is happen. In order to overcome this problem, in this paper, the use of discharge pulse counting methods to correct this error is introduced. The dimension error from micro-EDM processes by using discharge pulse counting method is much smaller than when using the positioning display indicator of micro-EDM machine. Hence, by using discharge pulse counting method, high precision machining can be achieved.     

Analysis of fractional Navier–Stokes equations

In this study, we apply the fractional Laplace variational iteration method (FLVIM), a computer methodology for exploring fractional Navier–Stokes equation solutions. In light of the theory of fixed points and Banach spaces, this paper also explores the uniqueness and convergence of the solution of general fractional differential equations obtained by the suggested method. In addition, the fractional Laplace variational iteration method solution's error analysis is covered. The computational technique also clearly demonstrates the validity and dependability of the suggested method for solving fractional Navier-Stokes equations. Furthermore, the obtained solutions are a perfect fit with previously established solutions.     

Controllability of Fractional Differential Equation of Order α∈(1,2] With Non‐Instantaneous Impulses

The objective of this paper is to establish the sufficient condition for the exact controllability of a control system governed by the fractional differential equation of order α∈(1,2] with non‐instantaneous impulses in a Hilbert space X. The results are obtained using the α‐order cosine family and Banach fixed point theorem. Also, the exact controllability of an integrodifferential problem is studied. Finally, a few examples are given to illustrate the applications of these abstract results.