During product design process, conventional case-based reasoning (CBR) has shown significant applications in coping with new problems by recalling and reusing solutions in old context. However, conventional CBR still lacks effective methods to assist designers in generating creative design solutions of identified problems during modification stage. To make up for this deficiency, an extended CBR (ECBR) method characterized by two retrieval stages is proposed in this paper. The former retrieval stage is aimed to retrieve the most similar source case for design reusing, and the latter one is designed to assist designers in searching for relevant function units to generate creative design ideas for final design solution. A five-tuple knowledge model of product case is presented. It includes both specific design information for design reusing and abstract function units for generating creative design ideas. To effectively organize these case information, a hierarchy knowledge model of case base is established. It consists of case type layer, product case layer, and function unit layer. A corresponding retrieval strategy is presented to deal with different retrieval goals. To improve the performance of ECBR method in modification stage, the substance-attribute-function-cause analysis model and TRIZ tools are integrated together to aid problem analysis and problem-solving of retrieved product case. Finally, a new product conceptual design process is proposed based on ECBR method and the conceptual design of a smokeless barbecue equipment is employed as an example to verify the feasibility and effectiveness of ECBR method.

In this paper, we consider a multi-antenna wireless multicast system with multiple multicast groups. The problem of resource allocation with downlink precoding for the multicast systems is studied, assuming the channel state information between transmit and all the receivers is available at the transmitter. Specifically, we formulate an optimization problem to maximize the system throughput given a set of available resources (power and subcarriers). A three-step algorithm is proposed, in which the multicast precoding process, subcarrier assignment and power allocation is operated separately to reduce the computational complexity. In two extreme cases, namely, low and high SNR regimes, the low-complexity allocation algorithm is further simplified. Simulation results also show that the system throughput is significantly improved by using our proposed algorithms both in multicast system and in unicast system.

The lack of information on the correlation between root causes and corresponding control criteria in the importance calculation of root causes of design problems results in less accurate determinations of core problems. Based on the interaction between customer needs, bad product parameters, and root causes, a hierarchical representation model of the design problem is established in this paper. A network layer of bad parameters, including various types of correlations, and a control layer, including technical feasibility and cost, are constructed. Then, a method based on the network analytic hierarchy process is proposed to rank the importance of root causes of the design problem and determine the core problems. Finally, a product design process based on the core problem solving is established to assist designers with improving design quality and efficiency. The design for the coolant flow distribution device in the lower chamber of a third-generation pressurized water reactor is employed as an example to demonstrate the effectiveness of the proposed method.