Ozer Igra has devoted most of his research activities to studying various aspects of shock and blast waves phenomena. His studies include both experimental and numerical investigations of strong (ionizing shocks in argon) and moderate to weak shock/blast wave in gases and in suspensions. Results of his investigations can be found in his many publications available in leading professional journals dealing with gas-dynamic flows and shock waves. He received his B.Sc. and M.Sc. degrees from the Department of Aeronautical Engineering of the Technion, Israel Institute of Technology and his Ph.D. from the Institute for Aerospace Studies, University of Toronto, Canada. He Joined the Ben Gurion University of the Negev in 1971. There he established the Shock Waves Laboratory, supervised many masters, doctorate and post-doc students and served as the chairman of the Department of Mechanical Engineering and thereafter as the Dean of the Faculty of Engineering. He is on the InternationalAdvisory Committee of the International Symposium on Shock Waves (ISSW) and the International Symposium on Shock Interactions (ISIS), and on the editorial board of the Shock Waves Journal.Kazuyoshi Takayama was born on April 3rd, 1940 in Sapporo Hokkaido, Japan. On March, 1963, he graduated from Nagoya Institute of Technology, entered Graduate School of Tohoku University, Department of Mechanical Engineering obtained Master Degree on March 1965 and obtained Doctor of Engineering on March 1970. He was appointed to be Lecturer of the Institute of High Speed Mechanics of Tohoku University on April 1970 and was promoted to Assistant Professor of the same. He spent his sabbatical from August 1977 to August 1979 in the University of Toronto Institute of Aerospace Studies (UTIAS).In 1980 he applied double exposure holographic interferometry to quantitatively visualize underwater shock waves which were generated by explosion of lead azide pellets of 4mg in weight. In collaborating with Professor M. Kuwahara of the Department of Urology, Medical School of Tohoku University, he worked on a design of extracorporeal shock wave lithotripsy using micro-explosives. This collaboration initiated medical applications of the shock waves to various clinical facilities.In April 1986, he was promoted to Professor of the High Speed Mechanics, Tohoku University and appointed to the Director of the Shock Wave Research Center, Institute of High Speed Mechanics, Tohoku University. In June 1989, the Institute of High Speed Mechanics was abolished and restarted as the Institute of Fluid Science.In April 1990, he launched the Shock Wave, an International Journal from the Sringer-Verlag, Heidelberg. Professor I.I. Glass of UTIAS was appointed to be the first editor-in-chief. In July 1991, he successfully hosted the 18th International Shock Wave Symposium (ISWS) in Sendai. Later the International Shock Wave Institute was established. Then, the Journal was published under the auspices of the International Shock Wave Institute. The transition of reflected shock waves over wedges in shock tube flows is one of the typical non-linear phenomena in high-speed gas dynamics. Discrepancies between analytical predictions and experiments are attributable presumably to the diaphragm ruptures in generating shock waves. In order to verify such effects, he worked on the design and the construction of highly reproducible shock tubes. In June 1994, Professor I.I. Glass of UTIAS gave him the 100mm×70mm cross sectional hypervelocity shock tube. He refurbished it to an elaborate diaphragm-less shock tube and eventually revealed that the disagreements of the reflected shock wave transition between analytical predictions and experiments are caused by the presence of boundary layers developing behind the shock waves.In March 2004 he retired but continued to work on Interdisciplinary Shock Wave Research as a vising Professor of theInstitute of Fluid Science, Tohoku University and fully retired in March 2011. His research works are summarized in the Visualization of Shock Wave Phenomena published by Springer-Verlag Heidelberg (2019).
