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91.
This article investigates a hybrid procurement mechanism that combines a reverse auction with flexible noncompetitive contracts. A buyer adopts such mechanism to procure multiple units of a product from a group of potential suppliers. Specifically, the buyer first offers contracts to some suppliers who, if accepting the contract, do not participate in the auction while committing to selling a unit to the buyer at the price of the subsequent auction. For the suppliers rejecting the offers, they can join the subsequent auction with the other suppliers to compete on the remaining units. When the buyer offers only one flexible noncompetitive contract, we find that the selected supplier may accept the offer regardless of whether he knows his exact cost information. Meanwhile, the buyer can benefit from offering such a contract, as opposed to solely conducting a regular reverse auction or offering a noncompetitive contract that does not allow suppliers declining offers to join the subsequent auction. Moreover, we find that the suppliers' information about their own costs has a significant impact on the buyer's decision. When the buyer makes multiple offers, we analyze the resulting game behavior of the selected suppliers and demonstrate that the buyer can benefit more than just offering one such contract. Therefore, the hybrid procurement mechanism can be mutually beneficial for both the buyer and the selected suppliers. 相似文献
92.
A common problem faced by many firms in their supply chains can be abstracted as follows. Periodically, or at the beginning of some selling season, the firm needs to distribute finished goods to a set of stocking locations, which, in turn, supply customer demands. Over the selling season, if and when there is a supply‐demand mismatch somewhere, a re‐distribution or transshipment will be needed. Hence, there are two decisions involved: the one‐time stocking decision at the beginning of the season and the supply/transshipment decision throughout the season. Applying a stochastic dynamic programming formulation to a two‐location model with compound Poisson demand processes, we identify the optimal supply/transshipment policy and show that the optimal initial stocking quantities can be obtained via maximizing a concave function whereas the contribution of transshipment is of order square‐root‐of T. Hence, in the context of high‐volume, fast‐moving products, the initial stocking quantity decision is a much more important contributor to the overall profit. The bounds also lead to a heuristic policy, which exhibits excellent performance in our numerical study; and we further prove both the bounds and the heuristic policy are asymptotically optimal when T approaches infinity. Extension to multiple locations is also discussed. 相似文献
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Davis K 《Social science》1986,71(1):1-5
The current revolution in sex roles is not simply the result of feminist ideology; it is a consequence of the demographic changes that have occurred during this century. Women seek work outside the home in response to a situation created, in part, by the decline in birth and mortality rates. Engaging in productive labor is not, however, a new activity for married women. In fact, the male "breadwinner" system of the last century has been a historical aberration. Women have traditionally participated in production. Feminism clearly provides an ideological basis for the new egalitarianism in marriage, but it is not possible to meaningfully examine the changing sex roles during this century without also examing the concurrent demographic trends. 相似文献
97.
Optimal three-stage designs with equal sample sizes at each stage are presented and compared to fixed sample designs, fully sequential designs, designs restricted to use the fixed sample critical value at the final stage, and to modifications of other group sequential designs previously proposed in the literature. Typically, the greatest savings realized with interim analyses are obtained by the first interim look. More than 50% of the savings possible with a fully sequential design can be realized with a simple two-stage design. Three-stage designs can realize as much as 75% of the possible savings. Without much loss in efficiency, the designs can be modified so that the critical value at the final stage equals the usual fixed sample value while maintaining the overall level of significance, alleviating some potential confusion should a final stage be necessary. Some common group sequential designs, modified to allow early acceptance of the null hypothesis, are shown to be nearly optimal in some settings while performing poorly in others. An example is given to illustrate the use of several three-stage plans in the design of clinical trials. 相似文献
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Sport participation and positive development in older persons 总被引:2,自引:1,他引:1
Joseph Baker Jessica Fraser-Thomas Rylee A. Dionigi Sean Horton 《European review of aging and physical activity》2010,7(1):3-12
In many Western countries, more and more people are living longer. As part of this demographic shift, increasing numbers are
participating in Masters sport. In the past, sport was considered important for the development of young people; however,
the potential for sport participation to affect positive development across the lifespan is now recognized. The purpose of
this paper is to introduce conceptual frameworks from developmental psychology that are being used to understand youths’ positive
development through sport, and to explore these frameworks in the context of sport as an avenue for positive development in
older persons. To achieve this aim, we outline research on sport participation as it applies to youth development and consider
relevant aspects as they broadly apply to development later in life. This discussion highlights the inherent paradox of sport
participation—that it has the potential to provide considerable positive growth but also the potential for significant negative
consequences. Finally, we explore areas of future research related to positive development in older persons through sport. 相似文献