With the development of the society and the progress of science and technology, people have more requests on the quality, variety and function of products and the global market competition becomes harder. How enterprises can develop new products with high quality, low costs as soon as possible is a new focus of the market competition. Concurrent Engineering(CE) is a systematic approach to the integrated , concurrent design of products and their related processes ,including manufacture and surpport. As an important competition approach, CE has been used in many enterprises and has made great good influences. Because the scheduling of design activities can reduce the product development cycle, which is the main purpose of CE, the design activities scheduling problem is an essential part of CE .This dissertation is concerned with two respects of the problem :1)the modeling of the design activities scheduling problems and 2)the heuristic methods to schedule them. Main contributions of the dissertation are as follows: 1.Models of scheduling problems with different scheduling envionments and object are constructed. In the models, three kinds of situations of the product development project and objects based on time, resource costs, and the trade-off between them are considered. To reflect the pratical situation of the product design, the extended precedence constraints are intrduced into the models too. 2.Several heuristic scheduling algorithms are constructed to solve the scheduling problems. To the scheduling problems with time object, a basic procedure based on sequencing and two improved procedures based on beam search method are proposed .All these procedures avoid the NP hard problem and one of the improved procedure gets satisfying result. To the scheduling problems with resource cost object, a heuristic algorithm is constructed and the convergence of the algorithm is discussed. 3.Theoriticaly,several theorems are proved .One of them is that with the assumption of preemption being allowed and other conditions being equal, the scheduling problem with extended precedence constraints equals to the the scheduling problem with normal precedence constraints.The other two theorems are about the existence of optimal solutions of the scheduling problems with resource cost object or time/resource cost trade-off object. 4.A method is provided to solve the cycle problem which occurs frequently in a design process. And because both static scheduling and dynamic scheduling strategy have their own merits and dismerits, a so-called semi-dynamic scheduling strategy is proposed. The dissertation also gives the concepts of the Resource Absence Degree, Resource Importance Degree and Task Performance Gain.
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