Remaining life estimation of used components in consumer products: Life cycle data analysis by Weibull and artificial neural networks

Environmental awareness and legislative pressures have made manufacturers responsible for the take-back and end-of-life treatment of their products. To competitively exploit these products, one option is to incorporate used components in “new” or remanufactured products. However, this option is partly limited by a firm's ability to assess the reliability of used components. A comprehensive two-step approach is proposed. The first stage phase statistically analyzes the behavior of components for reuse. A well-known reliability assessment method, the Weibull analysis, is applied to the time-to-failure data to assess the mean life of components. In the second phase, the degradation and condition monitoring data are analyzed by developing an artificial neural network (ANN) model. The advantages of this approach over traditional approaches employing multiple regression analysis are highlighted with empirical data from a consumer product. Finally, the Weibull analysis and the ANN model are then integrated to assess the remaining useful life of components for reuse. This is a critical advance in sustainable management of supply chains since it allows for a better understanding of not only service requirements of product, but the remaining life in a product and hence its suitability for reuse or remanufacture. Future work should assess: (1) reduction in downtime of process equipment through the implementation of this technique as a means to better manage preventative maintenance; (2) reduce field failure of remanufactured product; (3) selling-service strategy through implementation of the proposed methodology.     

Designing a guideline-based utilization management program

Many public and private organizations are developing and publishing clinical guidelines to assist health care providers and patients in making appropriate medical decisions. Unless clinical guidelines are part of a well-designed managed care program, they have little effect on physician practice styles. This article explores integral components of an effective guideline-based utilization management program. Initial evaluation of this program suggests that, as part of a well-designed utilization management program, clinical guidelines can inform patients and physicians, and create appropriate incentives for effective health care delivery.     

Growth and equity effects of changing demographic structures in the Netherlands: simulations within a social accounting matrix

"This paper deals with the economic consequences of a changing demography in an industrialized country, namely the Netherlands. The analytical framework chosen is that of general equilibrium as statistically given by the social accounting matrix (SAM) in which we introduce households by size for the present economic demographic situation (1981) and for a future simulated situation (2010) featuring in particular a relative increase in one-person households (individualization). The income (output) multipliers of both SAMs show a positive growth bias towards three and more person households and towards mining, public utilities, trade and banking."     

Intention and Stochastic Outcomes: An Experimental study

Do people care about intentions – even when good intentions do not produce good results? In our experiments we find that rates of punishment and reward react strongly to intentions (the wage a firm decides to pay) and more modestly to distributional outcomes (the higher or lower wage actually received including the stochastic component). For example, workers who end up receiving medium wages respond much more positively when this resulted from the firm offering a high wage but bad luck lowered the worker's pay than when this resulted from the firm offering a low wage and good luck raised the pay.     

Regional, national, and spatially explicit scenarios of demographic and economic change based on SRES

We report here spatially explicit scenario interpretations for population and economic activity (GDP) for the time period 1990 to 2100 based on three scenarios (A2, B1, and B2) from the IPCC Special Report on Emissions Scenarios (SRES). At the highest degree of spatial detail, the scenario indicators are calculated at a 0.5 by 0.5 degree resolution. All three scenarios follow the qualitative scenario characteristics, as outlined in the original SRES scenarios. Two scenarios (B1 and B2) also follow (with minor adjustments due to scenario improvements) the original SRES quantifications at the level of 4 and 11 world regions respectively. The quantification of the original SRES A2 scenario has been revised to reflect recent changing perceptions on the demographic outlook of world population growth. In this revised “high population growth” scenario, A2r world population reaches some 12 billion by 2100 (as opposed to some 15 billion in the original SRES A2 scenario) and is characterized by a “delayed fertility transition” that is also mirrored in a delayed (economic) development catch-up, resulting in an initially stagnating and subsequently only very slow reduction in income disparities. The spatially explicit scenario interpretation proceeds via two steps. Through a combination of decomposition and optimization methods, world regional scenario results are first disaggregated to the level of 185 countries. In a subsequent second step, national results are further disaggregated to a grid cell level, taking urbanization and regional (rural–urban) income disparities explicitly into account. A distinguishing feature of the spatially explicit scenario results reported here is that both methodologies, as well as numerical assumptions underlying the “downscaling” exercise, are scenario-dependent, leading to distinctly different spatial patterns of population and economic activities across the three scenarios examined.     

Welfare effects of 1992: A general equilibrium assessment for EC and EFTA countries

In this paper production, trade and welfare effects of European integration are discussed, with particular emphasis on the effects for the EC and EFTA. Insights from previous partial and general equilibrium analyses of the internal market are reviewed, and new model simulations are presented. In addition to the standard experiments of 1992 — as reduced trade costs and as full market integration — for the EC alone, and for the European Economic Area (EEA), an intermediate case, with full integration in the EC but only lower trade costs between the EC and EFTA, is analysed. All cases show that EFTA will benefit significantly from freer trade and closer integration with the EC. With regard to non-European regions, the simulations of European integration show some degree of trade diversion, but stylized model experiments indicate that a successful outcome of the Uruguay-round may more than offset the trade-diverting effects of 1992.     

Some comparative-statics results for nonlinear input-output models of a multisectored economy,and related results for nonlinear price-demand relations

For a nonlinear version of the linear input-output model of Leontief, we consider the effect, on the vector x of total gross outputs, of changes in the components of the final-demand vector c. For example, it is shown that, for a certain important class of models, the “large-change elasticity” of any component of x, with respect to any component of c, is less than or equal to unity. Some similar results are proved concerning properties of nonlinear price-demand relations for the case in which all goods are weak gross substitutes. Unlike earlier work in this general area, we do not introduce hypotheses concerning the indecomposability or homogeneity of certain mappings. For that reason, the results are valid for the price-demand relation for a single firm, or for any collection of firms.     

The demand for game day attendance in college football: an analysis of the 1997 Division 1‐A season

This paper develops a predictive model which includes game, team and university specific factors that are likely to influence game day demand for Division 1‐A college football. Attendance during the 1997 regular season is used as the dependent variable. Tobit estimates of two separate equations reveal that the quality of both teams, traditional rivalry and membership of specific conferences have a significant influence on demand. In addition, colleges with lower enrollments and a higher percentage of off‐campus students attract smaller crowds. The presence of a nearby professional football team also detracts from a college team's drawing power. Copyright © 2003 John Wiley & Sons, Ltd.     

Equipment replacement policy: a survey

Over the past ten years there has been a considerable increase in application of theoretically correct measurement methods in determining the economic life of equipment. Approximately 89% of the firms surveyed have equipment replacement policies. The discounted rate of return method is the most widely used in determining the service life of equipment; the MAPI formula is not widely used. Difficulties in applying a replacement policy can be classified into three groups: operational, organizational, and economic. The problems mentioned most often are operational. In organizational difficulties there is usually a lack of coordination between staff and line managers. Economic problems are generally the limited funds available for equipment replacement. Formal educational programs are lacking for the development of equipment replacement managers. For the firms having replacement policies, individuals with engineering degrees are preferred over those in other disciplines for the management of the equipment replacement policy.     

Estimation of a non-invertible moving average process: The case of overdifferencing

The effect of differencing all of the variables in a properly specified regression equation is examined. Excessive use of the difference transformation induces a non-invertible moving average (MA) process in the disturbances of the transformed regression. Monte Carlo techniques are used to examine the effects of overdifferencing on the efficiency of regression parameter estimates, inferences based on these estimates, and tests for overdifferenccing based on the estimator of the MA parameter for the disturbances of the differences regression. Overall, the problem of overdifferencing is not serious if careful attention is paid to the properties of the disturbances of regression equations.