SUMMARYNumerical simulation of a two-dimensional mixed compression supersonic inlet is carried out by solving unsteady compressible Euler equations via a stabilized ÿnite element method. The geometry of the inlet is similar to the one used by Anderson and Wong for experimental investigation for Mach 3 ow. The computations are capable of simulating the start-up problems associated with the inlet. The critical back pressure for the successful operation of the inlet is computed. The e ect of inlet back pressure on the total pressure recovery and the ow distortion level is analysed. Contrary to the popular belief, it is found that in addition to the throat to inlet capture area ratio, the ramp geometry close to the throat plays an important role in the start-up dynamics. It is demonstrated via simulations that, everything else being same, the geometries of ramp upstream of the throat that are associated with a curvature higher than a certain threshold, result in unstarting the intake.

Security games, and important class of Stackelberg games, are used in deployed decision-support tools in use by LAX police and the Federal Air Marshals Service. The algorithms used to solve these games find optimal randomized schedules to allocate security resources for infrastructure protection. Unfortunately, the state of the art algorithms either fail to scale or to provide a correct solution for large problems with arbitrary scheduling constraints. We introduce ASPEN, a branch-and-price approach that overcomes these limitations based on two key contributions: (i) A column-generation approach that exploits a novel network flow representation, avoiding a combinatorial explosion of schedule allocations; (ii) A branch-and-bound algorithm that generates bounds via a fast algorithm for solving security games with relaxed scheduling constraints. ASPEN is the first known method for efficiently solving massive security games with arbitrary schedules.

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