Engineering Costs and Production Economics最新文献

In this paper, the economic dispatch problem of a power system is formulated mathematically by using a linear load flow model. The generation cost is considered as a quadratic function of the generated active power of the generating nodes of the power system. Thus, the optimum allocation of active power generation, among the generating nodes, can be calculated for minimum generation cost.

The interest on Automated Guided Vehicle Systems (AGVS) research has increased significantly in the last decade. Among the many issues associated with the design and planning of AGV systems, a key problem is the vehicle management problem. In this paper, we give a comprehensive review and discussion of the procedures proposed in the literature.

Bulk conveyor systems often employ bins to segregate flow and to prevent interruptions in material handling. Analytical methods for sizing these bins were explored for the case when they serve multiple loading sources, each discharging a series of individual loads onto the conveyor. These methods included both an exact expression of the probability distribution for the required bin capacity and a normal approximation. The two analytical methods and a simulation model were used to size bins for some real and hypothetical applications. In comparing the modeling results of each method, only minor differences in the bin sizes were seen. For the applications examined, the normal approximation would be preferred as very little computational effort is required.

This paper reports the results of a study into the economic replacement of the auxiliary power supply units that are installed in every two-car unit making up passenger trains. The core of the study is the determination of when the existing power supply units should be replaced by more technically advanced units. Conventional theory is used to determine the resulting internal rate of return for replacement at different points in time. The paper also discusses the many subjective factors involved and the assumptions that will need to be made in order to solve large replacement problems of this kind.

Inventory system costs tend to be higher if uncertainty prevails in the supply lead times and consequently in the demand during the lead time because of the possibility of shortages or the need to maintain larger safety stocks. In this paper we explore a dual-sourcing technique in which the replenishment order quantity for the inventoried item with stochastic lead times is split between two sources of supply, and split-orders are placed simultaneously. It is shown that this results in effective lead times with lower variability and hence savings in the inventory holding and shortage costs are possible. If these savings exceed the incremental ordering costs associated with procurement from two sources overall cost economies result. In this paper, the theoretical concepts underlying the dual-sourcing technique and its implications for implementation in procurement management are presented along with an overview of the recent research in the area of dual sourcing.

Historically, the study of economic equipment replacement is primarily limited to that of a single machining system. The replacement situation whereby the machines under consideration are part of a large integrated system has received little attention. There are two major difficulties in analyzing such a problem: the interactive nature of an integrated system and the combinatorial nature of replacement alternatives. This paper attempts to first view the production system as a network of centers, and then approach the multiple equipment replacement decision as a configuration selection problem. An elaborate example is included.