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The time, quality, and cost are three important but contradictive objectives in a building construction project. It is a tough challenge for project managers to optimize them since they are different parameters. This paper presents a time-cost-quality optimization model that enables managers to optimize multiobjectives. The model is from the project breakdown structure method where task resources in a construction project are divided into a series of activities and further into construction labors, materials, equipment, and administration. The resources utilized in a construction activity would eventually determine its construction time, cost, and quality, and a complex time-cost-quality trade-off model is finally generated based on correlations between construction activities. A genetic algorithm tool is applied in the model to solve the comprehensive nonlinear time-cost-quality problems. Building of a three-storey house is an example to illustrate the implementation of the model, demonstrate its advantages in optimizing trade-off of construction time, cost, and quality, and help make a winning decision in construction practices. The computational time-cost-quality curves in visual graphics from the case study prove traditional cost-time assumptions reasonable and also prove this time-cost-quality trade-off model sophisticated.

This paper studies on the discrete time dynamic flow model and its application. Time is taken as the main consideration, and based on the discrete time unit. Combined with a single source evacuation algorithm, the discrete-time dynamic network flow model for evacuation can be formulated. Given there is uncertainty in the number of escapees, it is unable to calculate the minimal evacuation time. However establishing a network dynamic flow evacuation model, the problem can be transformed into the maximum dynamic network flow problem. The model can produce lower bounds for the evacuation time without considering any individual behavior, the value can be used to evaluate or analyze the evacuation of the community.

95 p. The refrigeration cycles have wide applications in our daily lives and play an essential role in a sustainable development. The extensive utilization of refrigeration processes has caused severe consequences on global-warming. Therefore, reducing energy consumption in refrigeration cycles has been one of the major research fields for many years. Master of Science (Power Engineering)