This paper provides an overview and perspective of recent research and applications of statistical process monitoring.

Some current directions in the theory and application of statistical process monitoring

In this expository article we give an overview of some statistical methods for the monitoring of social networks. We discuss the advantages and limitations of various methods as well as some relevant issues. One of our primary contributions is to give the relationships between network monitoring methods and monitoring methods in engineering statistics and public health surveillance. We encourage researchers in the industrial process monitoring area to work on developing and comparing the performance of social network monitoring methods. We also discuss some of the issues in social network monitoring and give a number of research ideas.

An overview and perspective on social network monitoring

In this expository paper we give an overview of some statistical methods for the monitoring of social networks. We discuss the advantages and limitations of various methods as well as some relevant issues. One of our primary contributions is to give the relationships between network monitoring methods and monitoring methods in engineering statistics and public health surveillance. We encourage researchers in the industrial process monitoring area to work on developing and comparing the performance of social network monitoring methods. We also discuss some of the issues in social network monitoring and give a number of research ideas.

Through systematical experiments,the mechanical properties,carbonation characteristics and shrinkage properties of concretes with fly ash contents of 50% and 60% for long-term curing ages were investigated in more detail.The results show that,for the concretes with fly ash contents of 50% and 60%,their later strength increases so rapidly and have a little difference with that of concretes without fly ash when they were cured for long-term ages and added an appropriate amount of activator.Moreover,long-term curing ages can obviously increase their carbonation resistance and certainly improve their shrinkage propertiy,but almost have no effect on the tendency of shrinkage.

High-performance High-volume Fly Ash Concrete

Control charts based on the Poisson distribution are commonly used to monitor count data in attributes. However, the Poisson distribution is based on the underlying equidispersion assumption that is limiting as discussed by different researchers in the literature. Therefore, a generalized control chart is required that can be used to monitor both overdispersed and underdispersed count data. This article reviews the methods to implement for dispersed count data and present ideas for future work in this area. A comprehensive literature review for researchers and practitioners is presented in this article. Copyright © 2014 John Wiley & Sons, Ltd.

Control Charts for Dispersed Count Data: An Overview

Much of the research involving simultaneous monitoring of several related quality characteristics that follow a multivariate Poisson distribution has relied on using the normal approximation to the Poisson distribution in order to determine the appropriate control limits. In this paper, evaluation and implementation of MEWMA schemes for count rates using the multivariate Poisson framework itself are presented. We demonstrate that the multivariate EWMA chart-based directly on the multivariate Poisson distribution is superior to one based on normal-theory with respect to the in-control average run length. The proposed scheme performs similarly to one based on normal-theory for detecting an out-of-control process. We also illustrate a step-by-step numerical example on the practical use of the new control chart.

EWMA control charts for multivariate Poisson-distributed data

Concrete is the most widely used material in construction industries. Therefore, it is necessary to understand and when possible, improve the efficiency of a concrete production process. Statistical process control is generally applied to gain information about variation in the manufacturing process. Control charts can be implemented to monitor the various processes involved in the production, the delivery and construction of concrete. When historical data are available on various projects, better insight into operational procedures can be obtained through the use of control charts. This paper studies a series of statistical analysis procedures to analyze the compressive strength of concrete. The proposed method is based on combining the cumulative sum (CUSUM) control chart and a run chart (CUSUM-run chart) for early detection of shifts in the process mean. The combined charts address both the consumers' and the producers' perspectives. The CUSUM-run chart can aid the consumer in making decisions about accepting or rejecting a strength test. In addition, the producers (concrete manufacturers) can use the chart to determine if the monitored process is out-of-control and subsequently attempt to identify the possible causes for the out-of-control situation. By identifying assignable causes of the out-of-control process, the producer can then improve the manufacturing process by reducing product variation, unnecessary waste, or over-designed concrete mixtures. The CUSUM-run chart is also beneficial in that it can often indicate when the strength of mixture is less than the minimum acceptable level very quickly. The delay in detecting an unacceptable strength can result in more penalties, project delays and increased associated costs.

Hybrid Control Charts for Active Control and Monitoring of Concrete Strength

This paper introduces a one-sided multivariate exponentially weighted moving average MEWMA chart for detecting an increase in a process mean. The control limits are based on the multivariate Poisson distribution and have applications for both industrial processes and public health data. The statistical performance of the proposed MEWMA is examined using run length distributions and is also compared to the traditional MEWMA based on normal-theory limits. Two out-of-control scenarios are of interest: 1 detecting a single point plotting beyond the control limits; 2 a run of two or more points in a row.

A one-sided MEWMA control chart for Poisson-distributed data

This research project addresses the opportunity to contain the escalating costs of concrete materials in construction projects. Both statistical process control and rational acceptance criteria show that quality improvement and cost savings can be achieved. The report presents a comprehensive statistical evaluation of the compressive strength of concrete used in various sectors of the transportation infrastructure in Arizona. The proposed methodology is applicable to the concrete materials specified at other industrial sectors such as privately financed construction projects. Several case studies are conducted based on actual field data to show that performance based specification procedures can be used to improve the quality control process while decreasing the overall construction costs. Three sets of compressive data from various construction projects were selected. These data were evaluated by means of statistical process-control tools while state-of-the-art procedures were utilized to evaluate the strength as a measure of quality. Several acceptance criteria based on the percent within limit (PWL) and operational-characteristic curves (OC) are proposed and evaluated. Various pay factor equations are considered and the historical records are evaluated based on hypothetical pay factor equations.

https://rosap.ntl.bts.gov/view/dot/5629/dot_5629_DS1.pdf

Development of Rational Pay Factors Based on Concrete Compressive Strength Data

This report showcases several new approaches of using materials science and structural mechanics to accomplish sustainable design of concrete materials. The topics addressed include blended cements, fiber-reinforced concrete (FRC), internal curing with lightweight aggregate, and statistical process control (SPC). Materials, methodologies, and test methods to enhance the performance and durability of concrete are addressed. Properties of pozzolans, blended cements, fly ashes, and other materials, along with proposed categories of high-performance concrete (HPC) mixtures using high-volume fly ash are briefly described. Early-age cracking and drying shrinkage are addressed in detail, as they both reduce load-carrying capacity and accelerate deterioration, resulting in increased maintenance costs and reduced service life. New developments in HPC materials using FRC are proposed, and it is shown that considerable cost savings can be realized by using fiber concrete mixtures. Internal curing techniques as a means of improving the quality of concrete using pre-soaked lightweight aggregate as an internal water supply were studied. The superior results of internally cured samples with lightweight aggregates, especially sintered bottom ash, indicate a great potential for using them in hot-weather concreting or when external curing is not possible. A new method for statistical data processing of concrete strength data also is presented. Technical tools were developed to improve performance-based specifications and statistical process control methods using cumulative sum (CUSUM) and exponentially weighted moving average (EWMA). Both of these approaches allow for process control and quality control (QC) monitoring of the materials. This report concludes with specifications for quality assurance (QA) and introduces quality measures as criteria for reducing the costs.

Busaba Laungrungrong

Papers

EWMA control charts for multivariate Poisson-distributed data

Hybrid Control Charts for Active Control and Monitoring of Concrete Strength

A one-sided MEWMA control chart for Poisson-distributed data

Development of Rational Pay Factors Based on Concrete Compressive Strength Data

Economical Concrete Mix Design Utilizing Blended Cements, Performance-Based Specifications, and Pay Factors