Phillip A. Farrington

Age-Related Differences in the Motivation of Knowledge Workers

Abstract: With the impending retirement of the Baby Boom Generation, retention of older knowledge workers, defined as engineers, scientists, and information technologists, has become important to engineering managers. Traditional theories of worker motivation have not adequately addressed the impact of worker age on factors that affect worker motivation. The study outlined in this article gathered data regarding the satisfaction and importance of motivational factors to determine if there are differences in their impact on older and younger knowledge workers.

A comparison of cohesion metrics for object-oriented systems

Abstract Cohesion is the degree to which the elements of a class or object belong together. Many different object-oriented cohesion metrics have been developed; many of them are based on the notion of degree of similarity of methods. No consensus has yet arisen as to which of these metrics best measures cohesion; this is a problem for software developers since there are so many suggested metrics, it is difficult to make an informed choice. This research compares various cohesion metrics with ratings of two separate teams of experts over two software packages, to determine which of these metrics best match human-oriented views of cohesion. Additionally, the metrics are compared statistically, to determine which tend to measure the same kinds of cohesion. Differences in results for different object-oriented metrics tools are discussed.

A weighted variance capability index for general non‐normal processes

Process capability indices are considered to be one of the important quality measurement tools for the continuous improvement of quality and productivity. The most commonly used indices assume that process data are normally distributed. However, many studies have pointed out that the normally-based indices are very sensitive to non-normal processes. Therefore we propose a new process capability index applying the weighted variance control charting method for non-normal processes to improve the measurement of process performance when the process data are non-normally distributed. The main idea of the weighted variance method is to divide a skewed or asymmetric distribution into two normal distributions from its mean to create two new distributions which have the same mean but different standard deviations. In this paper we provide an example, a distribution generated from the Johnson family of distributions, to demonstrate how the weighted variance-based process capability indices perform in comparison with another two non-normal methods, namely the Clements and Johnson–Kotz–Pearn methods. This example shows that the weighted variance-based indices are more consistent than the other two methods in estimating process fallout for non-normal processes. Copyright

Evaluation of the performance domain of cellular and functional layouts

This paper examines the effect of system configuration, underlying system structure, demand variation, and operation time variability on overall system performance. Three specific system configurations were investigated: a cellular manufacturing system, a dedicated job shop, and a pure job shop. System performance was compared based on five traditional measures and three managerial measures. The traditional measures were average flow time, average job lateness, average work-in-process levels, average distance moved per order, and average machine utilization. The managerial measures were average numer of departmental interactions per order, average number of open orders in each department, and mean time to reappearance of parts in the same family at machines. The results indicate that the demand pattern variability and processing time variability exert the greatest impact on the measures of system performance. In general, the cellular systems performed the best under conditions of low processing time variability. In addition, machine dedication in a batch production environment seriously degraded system performance.

Mentoring of Scientists and Engineers: A Comparison of Gender

Abstract: This study investigates the influence of gender makeup of the mentor-protégé dyad (or pair) on mentoring roles associated with both career development and non-career support. The survey population consisted of 202 high technology protégés working in 22 organizations located in four countries. Results indicate that the overall mentoring program effectiveness is enhanced when the mentor and the protégé are of the same gender.

Overhanging Features and the SLM/DMLS Residual Stresses Problem: Review and Future Research Need

A useful and increasingly common additive manufacturing (AM) process is the selective laser melting (SLM) or direct metal laser sintering (DMLS) process. SLM/DMLS can produce full-density metal parts from difficult materials, but it tends to suffer from severe residual stresses introduced during processing. This limits the usefulness and applicability of the process, particularly in the fabrication of parts with delicate overhanging and protruding features. The purpose of this study was to examine the current insight and progress made toward understanding and eliminating the problem in overhanging and protruding structures. To accomplish this, a survey of the literature was undertaken, focusing on process modeling (general, heat transfer, stress and distortion and material models), direct process control (input and environmental control, hardware-in-the-loop monitoring, parameter optimization and post-processing), experiment development (methods for evaluation, optical and mechanical process monitoring, imaging and design-of-experiments), support structure optimization and overhang feature design; approximately 143 published works were examined. The major findings of this study were that a small minority of the literature on SLM/DMLS deals explicitly with the overhanging stress problem, but some fundamental work has been done on the problem. Implications, needs and potential future research directions are discussed in-depth in light of the present review.

Semantic software metrics computed from natural language design specifications

An approach using semantic metrics to provide insight into software quality early in the design phase of software development by automatically analysing natural language (NL) design specifications for object-oriented systems is presented. Semantic metrics are based on the meaning of software within the problem domain. In this paper, we extend semantic metrics to analyse design specifications. Since semantic metrics can now be calculated from early in design through software maintenance, they provide a consistent and seamless type of metric that can be collected through the entire lifecycle. We discuss our semMet system, an NL-based program comprehension tool we have expanded to calculate semantic metrics from design specifications. To validate semantic metrics from design specifications and to illustrate their seamless nature across the software lifecycle, we compare semantic metrics from different phases of the lifecycle, and we also compare them to syntactically oriented metrics calculated from the source code. Results indicate semantic metrics calculated from design specifications can give insight into the quality of the source code based on that design. Also, these results illustrate that semantic metrics provide a consistent and seamless type of metric that can be collected through the entire lifecycle.

Designing simulation experiments for evaluating manufacturing systems

Simulation experiments can benefit from proper planning and design, which can often increase the precision of estimates and strengthen confidence in conclusions drawn from the simulations. While simulation experiments are broadly similar to any statistical experiment, there are a number of differences. In particular, it is often possible to exploit the control of random numbers used to drive the simulation model. To illustrate the methodology described, four examples drawn from manufacturing are used.

An Exploration of Fisher's Framework for the Alignment of Supply Chain Strategy With Product Characteristics

Abstract: In his 1997 Harvard Business Review article, Fisher suggests that supply chain improvement efforts have not produced expected results due to misalignment of products with supply chain strategies. His framework appeals logically and researchers rapidly moved into modifications of Fishers premise. A critical missing component, however, is a quantitative analysis of the benefits of the proper classification of products and alignment with the appropriate supply chain strategies to optimize performance. Quantifiable proof of Fishers framework can strengthen the validity of the initial premise and expansions of his theory. This article presents such a quantitative analysis exploring the validity of Fishers framework for improving performance.

A Preliminary Assessment of the Relationships Between Project Success, System Engineering, and Team Organization

Abstract: Demand for improved functionality in modern aerospace systems has resulted in increased project complexity. Managers are finding it even more difficult to balance cost, schedule, and performance. Often, system engineering is proposed as a means to balance these demands; however, guidance on tailoring system engineering and team organization to effectively deploy team assets is often incomplete. This paper reports on the development and testing of a methodology to assess the relationship between project success, system engineering, and team organization. The initial work is showing promise in revealing correlations. Data is currently being gathered and analyzed on additional projects, relative to the initial project requirements as well as other similar projects. It is hoped that there will be sufficient data to statistically evaluate these relationships. The longterm goal of this project is to look at statistical relationships so that a project team can effectively tailor their system engineering processes.