Ian Ashdown has been named senior research scientist at TIR Systems Ltd., a developer of enabling technologies for solid-state lighting.   . . .   Mellanox Technologies Ltd., supplier of InfiniBand semiconductors, has appointed Yuval Leader as the vice president of systems solutions.   . . .   3D Systems Corp. has named Grant R. Flaharty executive vice president of global business operations and E. James Selzer senior vice president.