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James Albert Sethian (born 10 May 1954) is a professor of mathematics at the University of California, Berkeley, and the head of the Mathematics Group () at the United States Department of Energy's Lawrence Berkeley National Laboratory. He received his Ph.D from Berkeley in 1982 under the direction of Alexandre Chorin. Afterward he was an National Science Foundation postdoctoral fellow at the Courant Institute, under Peter Lax. He returned to Berkeley in 1985 where he is now a full professor. Sethian was elected member of the National Academy of Engineering (NAE) in 2008 as well as the National Academy of Sciences (NAS) in 2013. Sethian has acted as Interim Director Research at Thinking Machines Corporation, as well as held visiting positions at the National Center for Atmospheric Research and the National Institute of Standards and Technology. ==Work== Sethian has worked on numerical algorithms for tracking moving interfaces for over three decades, starting with his seminal 1982 work on curve and surface propagation in combustion, and his 1985 work on entropy conditions, curvature, stability of numerical algorithms. This work led to development of the level set method in 1988, which was developed jointly with Stanley Osher. These are numerical algorithms for tracking moving interfaces in complex situations, and have proved instrumental in a wide collection of applications, including semiconductor processing, fluid mechanics, medical imaging, computer graphics, and material sciences. Jointly with D. Adalsteinsson, Sethian then introduced the idea of adaptivity to level set methods, in which computational labor is focused on the evolving front: their Adaptive Narrow Band level set method and its variants are what makes level set methods efficient and practical, and are the most common form of these techniques in practice today. Together with Alexander Vladimirsky, Sethian developed a class of Dijkstra-like ordered upwind methods for solving static Hamilton–Jacobi equations. In the case of an Eikonal equation, the first method to do so was developed by Jon N. Tsitsiklis using a control-theoretic approach: followed shortly by Sethian's work on high order finite difference Dijkstra-like Fast Marching Methods. Ravikanth Malladi and Sethian pioneered the application of these techniques to image segmentation, Ron Kimmel and Sethian introduced them to robotic navigation and extended them to curved domains, and Mihai Popovici and Sethian were the first to use them as fast wave solvers in geophysical seismic imaging. Together with Sergey Fomel, Sethian invented Escape Arrival Methods for computing multiple arrivals in wave propagation and geophysical imaging. Algorithms based on the work of Sethian and his colleagues are now commonly used throughout science and engineering. Examples include informing engineers how to design more precise ink jet plotters, allowing physicians to analyze brain and cardiac images, aiding oil companies in locating petroleum reserves, and telling process engineers how to build reliable computer chips. He maintains the "level set methods and fast marching methods" webpage (), which is a popular resource for these methods, and provides a variety of applets, movies, and explanations for both the popular and technical audiences. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「James Sethian」の詳細全文を読む スポンサード リンク
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