Dara

Abstract: eBay and Yahoo allow sellers to list their auctions with a buy price at which a bidder may purchase the item immediately. On eBay, the buy-now option disappears once a bid is placed, while on Yahoo the buy-now option remains in effect throughout the auction. We show that when bidders are risk averse, both types of auctions raise seller revenue for a wide range of buy prices. The Yahoo format raises more revenue than the eBay format when bidders have either CARA or DARA. Bidders with DARA prefer the eBay auction, while bidders with CARA are indifferent between the two.

Abstract: The required computational effort in the areas of production planning and logistics, scheduling, distribution and resource allocation is reduced by a procedure for solving a Discrete Activity Resource Allocation (DARA) problem. The procedure begins by reducing all activities and resources which do not contribute to maximizing benefit. Thus, all infeasible and non-profitable activities are discarded and all non-constraining resources are discarded, thereby considerably simplifying the solution to the problem. Next, an automatic mathematical model formulation of the DARA problem is performed. Based on this model, a list of cliques and covers are generated. The linear relaxation of the DARA problem using standard linear programming software is solved, and the generated list of clique and cover induced inequalities is scanned to select a set violated by the solution of the linear relaxation of the DARA problem. For those inequalities found, constraints are appended to the formulated DARA problem, forming another DARA problem with the same set of variables, but with additional constraints. The new DARA problem is then solved using the previous solution as the start of the solution. Based on this solution, the generated list of clique and cover induced inequalities is again scanned, and this process is continued until no violated inequalities are found. At this point in the procedure, conventional branch-and-bound or branch-and-cut routines are used to solve the enlarged DARA problem. The solution yields the optimal resource allocation producing the maximum benefit.

Abstract: A hybrid wireless-optical broadband access network (WOBAN) is a promising architecture for future access networks. Recently, the WOBAN has been gaining increasing attention, and early versions are being deployed as municipal access solutions. This architecture saves on network deployment cost because fiber need not penetrate to each end user. However, a major research opportunity exists in developing an efficient routing algorithm for the wireless front-end of the WOBAN. We propose and investigate the characteristics of the delay-aware routing algorithm (DARA) that minimizes the average packet delay in the wireless front-end of a WOBAN. In DARA we model wireless routers as queues and predict wireless link states periodically. Our performance studies show that DARA achieves less delay and congestion, and improved load balancing compared to traditional approaches such as the minimum-hop routing algorithm, shortest-path routing algorithm, and predictive throughput routing algorithm.