Zhen He
Tianjin University, College of Management & Economics, Faculty Member
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)... more
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 ...
Research Interests:
This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with... more
This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit:
Profile monitoring is used to check the stability of the quality of a product over time when the product quality is best represented by a function at each time point. However, most previous monitoring approaches have not considered that... more
Profile monitoring is used to check the stability of the quality of a product over time when the product quality is best represented by a function at each time point. However, most previous monitoring approaches have not considered that the argument values may vary from profile to profile, which is common in practice. A novel nonparametric control scheme based on profile error is proposed for monitoring nonlinear profiles with varied argument values. The proposed scheme uses the metrics of profile error as the statistics to construct the control charts. More details about the design of this nonparametric scheme are also discussed. The monitoring performance of the combined control scheme is compared with that of alternative nonparametric methods via simulation. Simulation studies show that the combined scheme is effective in detecting parameter error and is sensitive to small shifts in the process. In addition, due to the properties of the charting statistics, the out-of-control signal can provide diagnostic information for the users. Finally, the implementation steps of the proposed monitoring scheme are given and applied for monitoring the blade manufacturing process. With the application in blade manufacturing of aircraft engines, the proposed nonparametric control scheme is effective, interpretable, and easy to apply.
A robust desirability function approach to simultaneously optimizing multiple responses is proposed. The approach considers the uncertainty associated with the fitted response surface model. The uniqueness of the proposed method is that... more
A robust desirability function approach to simultaneously optimizing multiple responses is proposed. The approach considers the uncertainty associated with the fitted response surface model. The uniqueness of the proposed method is that it takes account of all values in the confidence interval rather than a single predicted value for each response and then defines the robustness measure for the traditional desirability function using the worst case strategy. A hybrid genetic algorithm is developed to find the robust optima. The presented method is compared with its conventional counterpart through an illustrated example from the literature.
The primary objectives of this study are (1) to develop a measurement model tied directly to the Baldrige criteria at both construct and dimension levels, and (2) to validate the theoretical model underlying the Baldrige framework based... more
The primary objectives of this study are (1) to develop a measurement model tied directly to the Baldrige criteria at both construct and dimension levels, and (2) to validate the theoretical model underlying the Baldrige framework based on evidence from China. Using both exploratory factor analysis and confirmatory factor analysis on data collected from 2302 manufacturing and service firms in China, authors find that the proposed theoretical model with 19 hypotheses are statistically supported at ,0.05 level. Contributions of this study are threefold: (1) the newly developed measurement model provides a neat and reliable reference for both practitioners and researchers; (2) the theoretical model developed was statistically supported regarding the overall model fit indices and hypothesised linkages, demonstrating the robustness of the Baldrige framework; and (3) based on evidence from China, process management is the most important construct in the Baldrige framework, followed by leadership, which shows a slight departure from previous studies on industrialised countries.
A traffic accident can be considered as an example of the attribute events, and the number of the injured in each accident is called the event size. Some control charts have been developed for monitoring either the time interval (T)... more
A traffic accident can be considered as an example of the attribute events, and the number of the injured in each accident is called the event size. Some control charts have been developed for monitoring either the time interval (T) between the occurrences of an event or the event size (C) in each occurrence. This article studies the statistical monitoring of the attribute events in which T and C are monitored simultaneously and C is an integer. Essentially, it integrates a T chart and a C chart, and is therefore referred to as a T &C scheme. Our studies show that the new chart is more effective than an individual T chart or C chart for detecting the out-of-control status of the event, in particular for detecting downward shifts (sparse occurrence and/or small size). Another desirable feature of the T &C scheme is that its detection effectiveness is more invariable against different types of shifts (i.e. T shift, C shift and joint shift in T &C) compared with an individual T or C chart. The improvement in performance is achieved due to the simultaneous monitoring of T and C. The T &C 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).
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)... more
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).
Typically in the analysis of industrial data for product/process optimization, there are many response variables that are under investigation at the same time. Robustness is also an important concept in industrial optimization. Here,... more
Typically in the analysis of industrial data for product/process optimization, there are many response variables that are under investigation at the same time. Robustness is also an important concept in industrial optimization. Here, robustness means that the responses are not sensitive to the small changes of the input variables. However, most of the recent work in industrial optimization has not dealt with robustness, and most practitioners follow up optimization calculations without consideration for robustness. This paper presents a strategy for dealing with robustness and optimization simultaneously for multiple responses. In this paper, we propose a robustness desirability function distinguished from the optimization desirability function and also propose an overall desirability function approach, which makes balance between robustness and optimization for multiple response problems. Simplex search method is used to search for the most robust optimal point in the feasible operating region. Finally, the proposed strategy is illustrated with an example from the literature.
This article, the first in a series of three articles written by the Quality in Education Think Tank of the International Academy for Quality, focuses on the meaning and scope of quality in education...