Stochastic Dynamic System Suboptimal Control with Uncertain Parameters

The control of a linear system with random coefficients is studied here. The cost function is of a quadratic form and the random coefficients are assumed to be partially observable by the controller. By means of the stochastic Bellman equation, the optimal control of stochastic dynamic models with partially observable coefficients is derived. The optimal control is shown to be a linear function of the observable states and a nonlinear function of random parameters. The theory is applied to an optimal control design of an aircraft landing in wind gust.     

On Team Games: A Computational Structural Analysis

Team games are studied here with one performance index for the team as a unit in competition with one common opponent. A structural analysis is presented with the intent to simplify the computation of optimal decision and communication processes. The minimum principle and calculus of variations are used to compute time-optimal and quadratic-optimal trajectories for certain linear "pursuit-evasion" games. A composition method is presented to compute an approximate solution to the two-versus-one problem from the solution to two one-versus-one problems. Help zones of a second pursuer to assist in the "capture" of an evader are derived. The hierarchical command and communication structure for a quadratic linear game of N pursuers and one evader is derived. An approximation is generated which has a convenient ripple or recursive structure.     

Effects of HZE particle on the nigrostriatal dopaminergic system in a future Mars mission

Because of long duration travel outside the Earth's magnetic field, the effect of iron-rich high charge and energy (HZE) particles in Galactic Cosmic Rays on human body is the major concern in radiation protection. Recently attention has been directed to effects on the central nervous system in addition to mutagenic effects. In particular, a reduction in striatal dopamine content on nigrostriatal dopaminergic system has been reported by investigators using accelerated iron ions in ground-based mammalian studies. In addition, studies of the pathophysiology of Parkinson's disease demonstrated that excess iron cause a reduction in the dopamine content in the substantia nigra. This suggests an intriguing possibility to explain the selective detrimental effects of HZE particles on the dopaminergic system. Should these particles have biochemical effects, possible options for countermeasures are: (1) nutritional prevention, (2) medication, and (3) surgical placement of a stimulator electrode at a specific anatomic site in the basal ganglia.     

A Controllability Study for a Team Linear Quadratic Game

A controllability interpretation of team linear quadratic games, with one performance index for the team in competition with one common opponent, is conducted to provide criteria of choice of terminal unknowns for the optimal game solution and to facilitate the computations of the trajectories. Efficiency of the pursuers is expressed in terms of the team controllability. The criteria provide a perfect choice for particular team dispositions named "optimal teams," which are shown to neutralize the evader. The study produces a particularly simple method to dispose or place a team optimally and to compute the corresponding optimal solution.