Engineering and Process Economics最新文献

An operational, interactive MRP system can be used for the study of the impact of suboptimizing models on the economics of production as well as pretesting the effects of the inevitable changes caused by engineering revisions, vendor delays, production interruptions or customer demand and schedule changes. Both optimizing techniques and common hueristics applied to a modest Master Production Schedule can be treated with the simulation model incorporated in the MRP program. Since the advent of computer based MRP systems, managers have had the visibility to anticipate shortages through the planned availability displays of MRP exception reports. However, the economics of a decision are difficult to test in a real environment but with an MRP simulation model, the alternatives of expediting, de-expediting, lot size changes and Master Schedule changes can be costed particularly with respect to inventory investment.

This paper presents some fundamental and critical aspects of computer-based corporate planning systems with emphasis on financial models. Special considerations is given to the interaction between the user and the system. A method for deisgning the architecture of such interactive decision support system and some implementation techniques are derived from the discussion of operational systems. This method tries to cope with the problems inherent in the integration of planning models into the practical planning process.

A significant problem in investment planning for major facilities such as transport systems and public utilities results from the inseparability of capacity expansion decisions and operation control during expansion periods. Short-run pricing and capacity management decisions must be optimized within the context of the longer run decisions to expand productive capacity. In this paper, the time-staged capacity expansion problem is formulated as a dynamic programming problem. Each stage of the program is decomposed into a series of short-run optimization problems ahat solve for an optimal set of prices and operational control policies. The pricing problem is one of determination of a peak-load responsibility price schedule that includes future capacity costs. The operational control policies represent public policy decisions that allocate capacity to distinct categories of consumers.

The general formulation is applied to the particular problem of airport capacity expansion. This problem is characteristic of the class of public utility investment decision problems where demand is growing but is subject to considerable peaking. The output of the airport is consumed by distinct categories of consumers and is therefore subject to a variety of capacity allocation options.

The problem of choice from a given set of portfolios is a problem of ordering the proper set F of probability distribution functions. In this paper the relations between (first and second degree) stochastic dominance rules and certain mean-variance rules are explored. Conditions are given under which stochastic dominance efficient sets are contained in mean-variance efficient sets as well as conditions under which the sets coincide. In this light some recent empirical work on efficient sets of portfolios is reconsidered; theoretical and practical reasons are discussed which limit the applicability of stochastic dominance rules in portfolio analysis.

When coming down on skis from a great height, the view changes from a vast panorama to the small village down in the valley, where the blacksmith is repairing the horse sleigh.

Analogous to this example, first the problems of top management will be reviewed and after that the tools of the operational research technique will be mentioned.

In this way, by summing up the problems at top management level and those of the working team in one lecture, the relations will be more distinct.

A heuristic approach to the problem of portfolio management is introduced as a dynamic extension of the portfolio selection problem. Both term and option contracts are fitted into the proposed scheme in order to achieve a realistic model for practical purposes.

A multicomponent production equipment is analyzed that requires occasional overhauls and readjustments to cut back increasing runtime costs. In addition stochastic failures of components are reset by so—called minimal repair actions. The occurence of failures as well as the initial runtime costs form independent stochastic processes. Using renewal theoretic arguments the behaviour of the equipment is mathematically evaluated. For a generalized loss structure sufficiency criteria are derived to provide for maximum availability, minimum costs, and maximum returns (using a costs dependent policy) in the long run.

To quantify the take-over value of a business firm, classical cash flow projection techniques frequently fail because the business is evaluated as an independent alternative. In this paper we show how a computer-based corporate planning model may be used to evaluate a candidate for take-over by an acquiring multinational firm.

The main part of the corporate planning system was an operational optimization system, searching the optimal plan of allocation of product markets to companies. In the introductory stage of the modelbuilding the optimization was based on a heuristic algorithm. During the evaluation of the synergistic advantages of the take-over of a small competitor, the heuristic was compared with a more sophisticated mixed integer linear programming model. The results of this comparison are reported.