in this paper, two inverse problems of stephen kind with local (dirichlet) boundary conditions are investigated. in the first problem only a part of boundary is unknown and in the second problem, the whole of boundary is unknown. for the both of problems, at first, analytic expressions for unknown boundary are presented, then by using these analytic expressions for unknown boundaries and bounda...

ABSTRACT Background: The radiographic image accuracy depends on the X-ray film information visibility. Good visibility is found by good contrast. Radiation exposure parameters (kVp, mAs) and film processing conditions have impact on contrast. In dentistry radiography machines, exposure time and processing procedure are set by radiographer. No optimized exposure time and process...