Value of information in remanufacturing complex products

Remanufacturing facilities usually face a trade-off between limited information about remanufacturing yields and potentially long supplier lead times. To improve production performance, these firms may attempt to acquire more timely and accurate information about remanufacturing yields or alternatively, to reduce the lead times of purchased parts. We develop four decision-making models to evaluate the impact of yield information and supplier lead time on manufacturing costs. We identify the operating conditions under which these capabilities are valuable, along with their relative impact on facility performance. Each model is formulated as an infinite horizon, stochastic dynamic program (Markov decision process). Our results indicate that the yield information is generally quite valuable, while investments in supplier responsiveness provide trivial returns to products with few parts. However, as product complexity increases with large number of target parts, the value of short lead times increases.     

Spare parts inventory management with demand lead times and rationing

We study an inventory system that consists of two demand classes. The orders in the first class need to be satisfied immediately, whereas the orders in the second class are to be filled in a given demand lead time. The two classes are also of different criticality. For this system, we propose a policy that rations the non-critical orders. Under a one-for-one replenishment policy with backordering and for Poisson demand arrivals for both classes, we first derive expressions for the service levels of both classes. The service level for the critical class is an approximation, whereas the service level for the non-critical class is exact. We then conduct a computational study to show that our approximation works reasonably, the benefits of rationing can be substantial, and the incorporation of demand lead time provides more value when the demand class with demand lead time is the critical class. The research is motivated by the spare parts service system of a major capital equipment manufacturer that faces two types of demand. For this company, the critical down orders need to be satisfied immediately, while the less critical maintenance orders can be satisfied after a fixed demand lead time. We conduct a case study with 64 representative parts and show that significant savings (as much as 14% on inventory on hand) are possible through incorporation of demand lead times and rationing.     

Software process improvement as emergent change: A structurational analysis

This paper presents a framework that draws on Structuration theory and dialectical hermeneutics to explicate the dynamics of software process improvement (SPI) in a packaged software organisation. Adding to the growing body of qualitative research, this approach overcomes some of the criticisms of interpretive studies, especially the need for the research to be reflexive in nature.Our longitudinal analysis of the case study shows SPI to be an emergent rather than a deterministic activity: the design and action of the change process are shown to be intertwined and shaped by their context. This understanding is based upon a structurational perspective that highlights how the unfolding/realisation of the process improvement (intent) are enabled and constrained by their context. The work builds on the recognition that the improvements can be understood from an organisational learning perspective. Fresh insights to the improvement process are developed by recognising the role of the individual to influence the improvement through facilitating or resisting the changes. The understanding gained here can be applied by organisations to enable them to improve the effectiveness of their SPI programmes, and so improve the quality of their software.     

ON THE USE OF BUFFER INVENTORIES TO MINIMIZE COSTS WITH AN UNRELIABLE MACHINE

In this paper, we discuss the problem of quality control with an unreliable machine which produces defects at a rate of Λ₀, per unit when in-control and a rate of Lambda; ₁, when out-of-control (where Λ₁ Λ ₀). Every h time periods, we sample n units, count the number of defects, and (using a process based on a Shewart c-chart) test the hypothesis that the machine is in control by comparing the total number of defects to an upper control limit (UCL). More important, we introduce the concept that a buffer inventory which immediately follows the unreliable machine may reduce expected total costs. This buffer serves to delay the movement of items from the unreliable machine to the next stage of the production process. In this way, we can isolate and repair most defective items before they are embedded in a product downstream or sold to customers where repair is more costly. To search for the optimal control policy, we find bounds for n, h, and UCL; given values for these variables, we show how the optimal buffer size can be determined directly. Numerical results illustrate the magnitude of potential savings.     

An objective comparison of the cost effectiveness of three testing methods

Branch testing is a well established method for exercising software. JJ-path testing, whilst employed by some practitioners, is less popular, and the testing of JJ-pairs finds few adherents. In this paper an objective, practical study of the cost-effectiveness of these three testing methods is reported. The effectiveness of each method is assessed, in the presence of infeasible paths, not only on its ability to cover the specific structural element of code that it targets, but also on its ability to cover the structural elements targeted by the other two methods – the collateral coverage it achieves. The assessment is based on the results derived from experiments in which each of the three methods is applied to 35 units of program code.     

Global software development: Exploring socialization and face-to-face meetings in distributed strategic projects

Socialization is one means through which globally distributed teams (GDTs) can improve collaboration. However, harnessing socializing processes to support globally distributed collaboration is not easy. In particular, infrequent and limited face-to-face (F2F) contact between remote counterparts might result in difficulties in sharing norms, attitudes and behaviours. In this paper we seek to understand how dispersed teams create socialization in globally distributed settings. Based on data collected at SAP, LeCroy and Baan we conclude that, while F2F meetings are important in socializing remote counterparts, other activities and processes employed before and after F2F meetings are no less important. In particular, the paper highlights the importance of re-socializing remote counterparts throughout a project lifecycle. Re-socializing means supporting the re-acquisition of behaviours, norms and attitudes that are necessary for participation in an organization. We offer a framework in which three phases of creating, maintaining and renewing socialization in GDTs are discussed. The paper concludes by offering managers some guidelines concerning socialization in GDTs.