This paper studies different methods proposed so far for segmentation evaluation. Most methods can be classified into three groups: the analytical, the empirical goodness and the empirical discrepancy groups. Each group has its own characteristics. After a brief description of each method in every group, some comparative discussions about different method groups are first carried out. An experimental comparison for some empirical (goodness and discrepancy) methods commonly used is then performed to provide a rank of their evaluation abilities. In addition, some special methods are also discussed. This study is helpful for an appropriate use of existing evaluation methods and for improving their performance as well as for systematically designing new evaluation methods.

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Powder metallurgy FeNi/Cu composites with low thermal expansivity and high electrical (thermal) conductivity were fabricated. T he eVects of Cu content, FeNi particle size, sintering temperature, and rolling reduction on the coeYcient of thermal expansion (CT E) and electrical (thermal) resistivity were investigated. T he results show that the CT E and electrical resistivity were aVected by the volume fraction of the components, the particular properties of the FeNi alloy, diVusion between the FeNi particles and the Cu particles, and the distribution of the Cu particles and the FeNi particles. T he experiments indicated that the FeNi/Cu composites could be used as heat sinks in welding type bolt silicon rectifier tubes.MST /4315