The variable sampling interval X̄ chart with estimated parameters

The VSI chart has been investigated by many researchers under the assumption of known process parameters. However, in practice, these parameters are usually unknown and it is necessary to estimate them from the past data. In this paper, we evaluate and compare the performance of the VSI chart in terms of its average time to signal in the case where the process parameters are known and in the case where these parameters are estimated. We also provide new chart constants taking into account the number of phase I samples. Copyright © 2011 John Wiley & Sons, Ltd.     

Variation Of Airflow Pattern Through Dissimilar Valve Lift In A Spark Ignition Engine

Abstract

Bi-fuel conversions are a common alternative fuelling option for mono-fuel gasoline SI vehicles because of the minor vehicle modifications required. In Malaysia, most bi-fuel vehicles are fuelled with compressed natural gas (CNG) and gasoline. However, CNG flame speed is lower than gasoline reducing the power and range of the vehicle when operating on CNG. This situation can be improved by increasing the flame speed via higher swirl generation. A Computational fluid dynamics model is used to analyse swirl generated by dissimilar valve lift (DVL) profiles on the intake valve. A three-dimensional engine simulation shows differences in swirl motion and turbulence between the original symmetric valve lift profile and the DVL. The higher swirl number reduces the turbulence kinetic energy level slightly. The best case profile is selected for further experimental testing.     

Information deduction approach through quality function deployment for the quantification of the dependency between design tasks

The design structure matrix (DSM) has been widely known as an effective approach for the modelling and analysis of a design process for the manufacture of a product from the perspective of information flow. It provides a formal method to capture and manage the interactions and interdependences among design tasks. Nonetheless, the difficulties in constructing a reliable numerical DSM prevent wider applications of DSM and its derived techniques. In this work, an approach to quantify systematically the dependency between design tasks in a DSM is proposed. The proposed approach aims at estimating the coupling strength of tasks in a DSM by making full use of the information contained in quality function deployment matrices. To realize this, a house of quality matrix is first constructed, followed by transferring the information in the house of quality to an extended design deployment matrix, and then the dependence strength of each task–attribute pair in the extended design deployment matrix is analysed. The details of the proposed approach are presented. The performance of the proposed prototype is illustrated by using a case study on a burn-in system. The results obtained from the case study are discussed.     

Tailoring insoluble nanobelts into soluble anti-UV nanopotpourris

Soluble, transparent and anti-UV nanopotpourris have been prepared by tailoring long nanobelts. The strains and layered structures facilitate the breaking of the as-synthesized nanobelts under an applied mechanical action. The developed tailoring process of nanobelts is a general top-down secondary processing of layered nanostructures at the nanoscale level, which can be expended to the modifications of layered nanowires, nanotubes and hierarchical nanostructures. By tailoring, the size, morphology and solubility are modified, which may open up an area of advanced processing of nanomaterials and hint at some potential applications. Because of the excellent solubility of the tailored nanopotpourris, they are easily dispersed in cosmetics or polymer films, which are quite useful for some anti-UV protection applications, such as anti-UV sunscreen creams and anti-UV window films for vehicles and buildings.     

Efficacy of chlorine and peroxyacetic acid on reduction of natural microflora, Escherichia coli O157:H7, Listeria monocyotgenes and Salmonella spp. on mung bean sprouts

Sprouts-related outbreaks have risen due to increased raw sprouts consumption. To minimize such cases, chemical sanitations are applied. While chlorine is commonly used, concerns with its effectiveness and health implication have prompted researchers to seek alternatives. Peroxyacetic acid (PAA) has shown efficacy in inactivating foodborne pathogens on fresh vegetables, and hence could be considered as an alternative. Thus, the objective of this study was to compare the efficacy of chlorine and PAA in inactivating Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spp., and natural microflora on mung bean sprouts. Resistance of non- and acid-adapted pathogens to these sanitizer treatments was also evaluated. Un-inoculated and inoculated sprouts were treated with chlorine at 106, 130 and 170 ppm and PAA at 25, 51 and 70 ppm for 90 and 180 s at room temperature. Overall, the greater log reductions were obtained with the increase in the sanitizer concentration. For 180 s, chlorine treatment at 170 ppm reduced 2.0, 1.3, 1.5, 0.9-logs and PAA treatment at 70 ppm resulted in 2.3, 1.8, 2.1, 1.1-log reductions for non-adapted E. coli O157:H7, L. monocytogenes, Salmonella spp., and natural microflora, respectively. These results revealed that the efficacy of PAA was significantly better than or similar to that of chlorine. For acid-adapted cells, these sanitizer treatments were less effective with the ranges of 1.0–1.2-log reductions for chlorine and 1.1–1.6-log reductions for PAA compared to non-adapted cells, indicating that acid-adapted cells were more resistant to the sanitizing treatment. These data suggest that PAA may replace chlorine in the disinfection of mung bean sprouts and that acid-adapted pathogens should be used to design an effective sanitizing strategy.     

2011年全球前十大MEMS器件厂商排名

MEMS传感器除了传统应用如喷墨打印头、投影仪、麦克风、汽车等领域,它还广泛应用在手机、平板电脑等移动终端上,可为设备添加更多智能化功能。据IHS iSuppli公司的MEMS市场调查显示,2011年最大的十家MEMS厂商的合计营业收入为47亿美元,比2010年的42亿美元增长12%。德州仪器继续稳居全球最大的MEMS器件制造商地位,在激烈竞争中保住了冠军位置,惠普仍然屈居第二。十大MEMS厂商中其他几家按降序排列依次是博世、意法半导体、佳能、松下、电装、楼氏、ADI和爱普生。飞思卡尔半导体原来也位于十大厂商行列,但2011年排名第十一,跌出了前十之列。     

2012年苹果仍将是平板电脑销量冠军

虽然基于Android系统的平板电脑增长快速,但目前看来苹果仍将保持绝对领先的态势。随着英特尔超极本的推出以及Windows8面市,PC型平板或将成为平板市场上一股新的力量。据IHS iSuppli公司全球平板电脑市场追踪报告显示,2012年苹果公司将以其iPad系列产品轻松保持在全球平板电脑市场的绝对领先地位,尽管一众Android产品和基于PC的平板产品也在努力进入这个迅速增长的市场。今年包括媒体平板和PC型平板在内的平板电脑销量将增加到1.266亿台,比2011年的     

2011电视半导体市场增长势头减弱

由于价格压力沉重和电视销售低迷,去年电视主板上使用的半导体销售额萎缩,并迫使一些知名厂商永远退出该产业。不过随着新功能的推出,半导体企业仍存在增长机会。     

A Cumulative Sum scheme for monitoring frequency and size of an event

This article proposes a Cumulative Sum (CUSUM) scheme, called the TC‐CUSUM scheme, for monitoring a negative or hazardous event. This scheme is developed using a two‐dimensional Markov model. It is able to check both the time interval (T) between occurrences of the event and the size (C) of each occurrence. For example, a traffic accident may be defined as an event, and the number of injured victims in each case is the event size. Our studies show that the TC‐CUSUM scheme is several times more effective than many existing charts for event monitoring, so that cost or loss incurred by an event can be reduced by using this scheme. Moreover, the TC‐CUSUM scheme performs more uniformly than other charts for detecting both T shift and C shift, as well as the joint shift in T and C. The improvement in the performance is achieved because of the use of the CUSUM feature and the simultaneous monitoring of T and C. The TC‐CUSUM scheme can be applied in manufacturing systems, and especially in non‐manufacturing sectors (e.g. supply chain management, health‐care industry, disaster management, and security control). Copyright © 2009 John Wiley & Sons, Ltd.     

A study of time‐between‐events control chart for the monitoring of regularly maintained systems

Owing to usage, environment and aging, the condition of a system deteriorates over time. Regular maintenance is often conducted to restore its condition and to prevent failures from occurring. In this kind of a situation, the process is considered to be stable, thus statistical process control charts can be used to monitor the process. The monitoring can help in making a decision on whether further maintenance is worthwhile or whether the system has deteriorated to a state where regular maintenance is no longer effective. When modeling a deteriorating system, lifetime distributions with increasing failure rate are more appropriate. However, for a regularly maintained system, the failure time distribution can be approximated by the exponential distribution with an average failure rate that depends on the maintenance interval. In this paper, we adopt a modification for a time‐between‐events control chart, i.e. the exponential chart for monitoring the failure process of a maintained Weibull distributed system. We study the effect of changes on the scale parameter of the Weibull distribution while the shape parameter remains at the same level on the sensitivity of the exponential chart. This paper illustrates an approach of integrating maintenance decision with statistical process monitoring methods. Copyright © 2008 John Wiley & Sons, Ltd.