Editorial: Celebrating the 70th Anniversary of Professor Yongnian Yan: A life dedicated to science and technology

directly from computer generated models emerged in the 1980s under the name of rapid prototyping. The basic concept of rapid prototyping is layer laminate manufacturing where three-dimensional (3D) structures are formed by laminating thin layers according to two-dimensional (2D) slice data, obtained from a 3D model created on a CAD/ CAM system. Rapid prototyping emerged as a step forward in the product development cycle, reducing lead times for new products. Initially, additive technologies were used as rapid prototyping mainly employed for: i) physical verification of a previously defined CAD model, ii) form, fit and function testing, iii) creating models regardless of draft angles and parting lines; iv) concept presentations and design reviews, v) creating anatomical models designed from computeraided tomography (CAT) data for surgical planning and prosthesis design; vi) producing relief models for geographical applications; creating 3D portraits (three-dimensional photography) using data produced by 3D shape digitising technology, etc. In the 1990s, additive prototyping moved from rapid prototyping to rapid tooling. In this new domain, additive technologies were used for direct tooling as well to produce masters for rapid tooling, using conversion technologies like investment casting and silicone, epoxy and spray metal moulds. In the late 1990s, two new domains emerged of additive technologies’ applications. One is Rapid Manufacturing integrating computer automated production with intrinsic technology characteristics to make individual products in small volumes with no need of tooling. The other is Biomanufacturing combining the use of additive technologies, biodegradable and biocompatible materials, cells, growth factors, etc., to produce biological structures for tissue engineering applications. Professor Yongnian Yan was a pioneer in the field of additive technologies and played a key role in all the abovementioned major domains. He was born in Chongqing on January, 12, 1938 at Chongqing, China. After graduating from Tsinghua University in 1962, he stayed all his academic career at the same University. Professor Yan explored developed additive technologies in all its different aspects: materials, fabrication strategies, computer simulation, etc. He extended the use of these technologies to a wide range of new application fields and proposed novel fabrication principles such as the Rapid Ice Prototyping Forming. The first Chinese melted extrusion manufacturing system, called MEM-250-II, was also developed by his group at the Center for Laser Rapid Forming, Tsinghua University. Other systems developed by Professor Yan’s group were the Auro-350 a stereolitography machine and the Slicing Solid Manufacturing system based on the Laminated Object Manufacturing process. Professor Yan conducted relevant research in rapid tooling too. In this domain, he studied both the use of electroforming moulds based on stereolithography prototypes and the unbaked ceramic mould casting process based on the rapid prototyping technology. He also proposed a three-dimensional non-linear thermo-mechanical model for the computer simulation of the dimensional accuracy for casting dies in rapid tooling. In 2005, Professor Yan together with Professor Wei Sun (Drexel University), Myron Spector (Harvard Medical School) and Feng Lin (Tsinghua University) organised the first US China National Science Foundation-sponsored workshop on biomanufacturing. This workshop, which brought together multi-disciplinary researchers from United States, China, Australia and Portugal (Figure 1), Editorial: Celebrating the 70th Anniversary of Professor Yongnian Yan: A life dedicated to science and technology Virtual and Physical Prototyping, Vol. 3, No. 4, December 2008, 189 191