We report on an industrial project in which we developed an inventory model to provide decision support for the design and deployment of the field service support system for a remanufacturable product. The product was a dialysis unit for home use. Each unit that was installed in a home would eventually be removed due to failure, or the need for preventative maintenance, or the termination of the service. Upon removal, each unit was shipped to a central depot for re-manufacturing so that it could be returned to service. We develop a model to determine the inventory requirements at each regional depot, and then describe how to use the model to determine the inventory requirements in the two-echelon system consisting of the central facility and the regional depots. / Singapore-MIT Alliance (SMA)

In this paper, we study the stochastic transportation-inventory network design problem involving one supplier and multiple retailers. Each retailer faces some uncertain demand. Due to this uncertainty, some amount of safety stock must be maintained to achieve suitable service levels. However, risk-pooling benefits may be achieved by allowing some retailers to serve as distribution centers (and therefore inventory storage locations) for other retailers. The problem is to determine which retailers should serve as distribution centers and how to allocate the other retailers to the distribution centers. Shen et al. (2000) and Daskin et al. (2001) formulated this problem as a set-covering integer-programming model. The pricing subproblem that arises from the column generation algorithm gives rise to a new class of submodular function minimization problem. They only provided efficient algorithms for two special cases, and assort to ellipsoid method to solve the general pricing problem, which run in O(n⁷ log(n)) time, where n is the number of retailers. In this paper, we show that by exploiting the special structures of the pricing problem, we can solve it in O(n² log n) time. Our approach implicitly utilizes the fact that the set of all lines in 2-D plane has low VC-dimension. Computational results show that moderate size transportation-inventory network design problem can be solved efficiently via this approach. / Singapore-MIT Alliance (SMA)

We report on a project with Polaroid Corporation in which we developed a supply chain model to provide decision support for planning production and transportation. Production occurs in Asia to serve world-wide demand. Production planners must determine both the production quantities as well as whether to ship by sea or by air. We develop a model to optimize a static version of this problem and then show how to use this static model in a dynamic setting. We test the model with data from Polaroid and show its effectiveness. / Singapore-MIT Alliance (SMA)

We analyze an infinite horizon, single product, periodic review model in which pricing and production/inventory decisions are made simultaneously. Demands in different periods are identically distributed random variables that are independent of each other and their distributions depend on the product price. Pricing and ordering decisions are made at the beginning of each period and all shortages are backlogged. Ordering cost includes both a fixed cost and a variable cost proportional to the amount ordered. The objective is to maximize expected discounted, or expected average profit over the infinite planning horizon. We show that a stationary (s,S,p) policy is optimal for both the discounted and average profit models with general demand functions. In such a policy, the period inventory is managed based on the classical (s,S) policy and price is determined based on the inventory position at the beginning of each period. / Singapore-MIT Alliance (SMA)

Traditional inventory models focus on risk-neutral decision makers, i.e., characterizing replenishment strategies that maximize expected total profit, or equivalently, minimize expected total cost over a planning horizon. In this paper, we propose a framework for incorporating risk aversion in multi-period inventory models as well as multi-period models that coordinate inventory and pricing strategies. In each case, we characterize the optimal policy for various measures of risk that have been commonly used in the finance literature. In particular, we show that the structure of the optimal policy for a decision maker with exponential utility functions is almost identical to the structure of the optimal risk-neutral inventory (and pricing) policies. Computational results demonstrate the importance of this approach not only to risk-averse decision makers, but also to risk-neutral decision makers with limited information on the demand distribution. / Singapore-MIT Alliance (SMA)

The aim of this study was to determine the psychometric properties of a shortened version of the Zimbardo Time Perspective Inventory (ZTPI) in an African context. This self-report questionnaire, referred to as the Zimbardo Time Perspective Inventory -Revised Form (ZTPI-RF) consists of 20 items representing the five subscales of the original scale, namely: Past-Positive, Past-Negative, Present-Hedonistic, Present-Fatalistic and Future. The ZTPI-RF was completed by participants (N=1050) from urban (n=451) and rural (n=599) areas in the North-West Province of South Africa, together with a number of measures of psychological well-being. These scales, which were included for criterion-related validity purposes, were the Affectometer 2 (short version) (Kammann & Flett, 1983), the Satisfaction with Life Scale (Diener, Emmons, Larsen & Griffin, 1985), Sense of Coherence Scale (Antonovsky, 1987, 1993) and the General Health Questionnaire (Goldberg & Hillier, 1979). Results regarding the reliability and construct validity of the ZTPI-RF and its subscales were unsatisfactory. Qualitative data was also obtained, and analyzed by means of direct content analysis to help establish a picture of how time perspective prevails in an African context, and to determine whether time perspective is associated with psychological well-being. Qualitative results showed that participants from an African context were strongly oriented toward the present and that social support played the most prominent role regarding participants' attitude toward the present. It was concluded that the ZTPI-RF is, in its current form, not reliable for the determination of time perspective of individuals from an African context, and that a longitudinal qualitative approach might be best suited to obtain information about the nature and dynamics of time perspective in an African context. / Thesis (M.A. (Psychology))--North-West University, Potchefstroom Campus, 2008.

Thesis (Ph. D.)--Ohio State University, 1984. / Includes bibliographical references (leaves 171-177). Available online via OhioLINK's ETD Center.

A unique approach is developed for evaluating Human Capital (workforce) requirements. With this approach, new ways of measuring personnel availability are proposed and available to ensure that an organization remains ready to provide timely, relevant, and accurate products and services in support of its strategic objectives over its planning horizon. The development of this analysis and methodology was established as an alternative approach to existing studies for determining appropriate hiring and attrition rates and to maintain appropriate personnel levels of effectiveness to support existing and future missions. The contribution of this research is a prescribed method for the strategic analyst to incorporate a personnel and cost simulation model within the framework of Human Resources Human Capital forecasting which can be used to project personnel requirements and evaluate workforce sustainment, at least cost, through time. This will allow various personnel managers to evaluate multiple resource strategies, present and future, maintaining near “perfect” hiring and attrition policies to support its future Human Capital assets.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Fuel inventory and generation of carbon and metal dust in a tokamak are perceived to be serious safety and economy issues for the steady-state operation of a fusion reactor, e.g. ITER. These topics have been explored in this thesis in order to contribute to a better understanding and the development of methods for controlling and curtailing fuel accumulation and dust formation in controlled fusion devices. The work was carried out with material facing fusion plasmas in three tokamaks: TEXTOR in Forschungszentrum Jülich (Germany), Tore Supra in the Nuclear Research Center Cadarache (France) and JET in Culham Centre for Fusion Energy (United Kingdom). Following issues were addressed: (a) properties of material migration products, i.e. co-deposited layers and dust particles; (b) impact of fuel removal methods on dust generation and on modification of plasma-facing components; (c) efficiency of fuel and deposit removal techniques; (d) degradation mechanism of diagnostic components - mirrors - and methods of their regeneration. / <p>QC 20121116</p>