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This research considers a project scheduling problem with the object of minimizing weighted earliness-tardiness penalty costs, taking into account a deadline for the project and precedence relations among the activities. An exact recursive method has been proposed for solving the basic form of this problem. We present a new depth-first branch and bound algorithm for extended form of the problem, which time value of money is taken into account by discounting the cash flows. The algorithm is extended with two bounding rules in order to reduce the size of the branch and bound tree. Finally, some test problems are solved and computational results are reported. © 2008 Asian Network for Scientific... 

A mixed binary integer mathematical programming model is developed in this paper for ordering items in multi-item multi-period inventory control systems, in which unit and incremental quantity discounts as well as interest and inflation factors are considered. Although the demand rates are assumed deterministic, they may vary in different periods. The situation considered for the problem at hand is similar to a seasonal inventory control model in which orders and sales happen in a given season. To make the model more realistic, three types of constraints including storage space, budget, and order quantity are simultaneously considered. The goal is to find optimal order quantities of the... 

In this paper we develop two models; the without shortages and the completely backlogging shortages with the price dependant demand rate under time value of money and inflation, finite time horizon and exponentially deterioration rate with the objective of maximizing the present worth of the total system profit. Using the dynamic programming method for each model, we are able to obtain different selling price, order quantity and cycle length for each cycle. We also use a proper numerical example to show accuracy of the solution procedures and to compare the results. This research and its results are unique and have never been concluded before  

Nowadays the maintenance of the deteriorating structures is an important subject in industry and research. Due to the limitations of the budget and time, the optimization algorithms have been used widely to determine the best maintenance strategies to provide the more economical structures. On the other side, the Less life-cycle cost will result in less safe structures. As safety is a vital criterion for the users of a structural system, there is a severe need to make a suitable trade-off between cost and safety. So, the optimal maintenance strategies are those that fulfill both the safety and the economical requirements. In this paper, the reliability of the structural system is selected to... 

In this paper, an exact solution procedure is presented for the Weighted Earliness-Tardiness Project Scheduling Problem (WETPSP) with Generalized Precedence Relations (WETPSP-GPR), taking into account the time value of money (WETPSPDC-GPR) and a fixed deadline for the project. The WETPSP-GPR extends the WETPSP to arbitrary minimal and maximal time-lags between the starting and completion times of activities. We present a new depth-first Branch and Bound (B&B) algorithm for an extended form of the problem, in which the time value of money is taken into account by discounting cash flows, and minimum, as well as maximum, time-lags between different activities may be given. The algorithm is...