50 Years of Optimization in Japan Using Superstructures

One of the most important contributions of Japanese researchers is the proposition of the superstructure concept. Umeda and coworkers proposed in 1972 a system structure for a reaction-separation process structure in which split ratios determine the connecting flows. Later, this concept changed to structure parameter and, finally, to the superstructure. Since 1980, superstructure-based optimization has been a very active field in Process Systems Engineering (PSE). This review presents the research done in Japan over the last 50 years as a tribute to the pioneering work of Japanese engineers and researchers in Academia and Industry. Recent advancements in superstructure-based optimization are in the direction of low aggregation representations that contain functional modules covering phenomenological aspects. The synthesis of distillation structures, biomass utilization, supply chain networks, and (bio)pharmaceutical processes are active topics in Japan, and further extensions and applications are expected in the future.