Traditional approaches are based on Markov models, which cannot evaluate the reliability of systems whose components have arbitrary (non-exponential) time-to-failure distributions. To overcome the limitations of the existing methods, we developed and refined two combinatorial and analytical methods, one is based on the Sequential Binary Decision Diagram (SBDD) and another one is based on the Sequential Multistate Decision Diagram (SMDD). Several case studies were performed to illustrate the application and advantages of the proposed methods. The results of the proposed approaches can also be used as the objective function to solve the redundancy allocation problem for a WSP system in series-parallel. Genetic algorithm can be applied to allocate the redundancy for each subsystem and provide the optimal model that maximizes the reliability and still meets both cost and weight constraints. Solving redundancy allocation problem provide an economical as far as cost, weight and energy consumption without jeopardizing the reliability of the system. The research results from this work have applications in the practice of reliable design of complex systems in many disciplines such as computer engineering, electrical engineering, mechanical engineering, and power engineering. The project involves collaboration with researchers and students from NUS. We are currently working on more collaboration. The research results and knowledge related to the project have been publicized through two seminar talks. The project finding will also be disseminated through a journal paper that will be submitted soon. My learning experience falls beyond the technical aspects of the project. In fact, participating in problem solving activities, sharing ideas and doing fun programs with NUS students made this summer a rich experience in both research and cultural aspects. It has been a very interesting experience to be able to discuss work with people from different backgrounds, to see things from different perspectives and to perceive a various ways of thinking. I was exposed to the culture of East Asia with its various traditions and customs. In short, this trip had a substantial positive impact on my future career.