Orientation Control of a Satellite

In this paper we consider the problem of controlling the orientation of a satellite with thrusters which provide two control torques. We derive open loop steering control laws for steering the satellite from one orientation to another. Then, we develop closed loop regulation control laws. For a ﲳymmetric satellite, (i.e. one with two moments of inertia equal) we stabilize a five dimensional subset of the states. The regulator for the asymmetric satellite, which is controllable, renders an arbitrary configuration asymptotically stable. A novel choice of ﲌisting coordinates for SO (3) proves to be useful in deriving these control laws

Intra-molecular coupling as a mechanism for a liquid-liquid phase transition

We study a model for water with a tunable intra-molecular interaction $J_\sigma$, using mean field theory and off-lattice Monte Carlo simulations. For all $J_\sigma\geq 0$, the model displays a temperature of maximum density.For a finite intra-molecular interaction $J_\sigma > 0$,our calculations support the presence of a liquid-liquid phase transition with a possible liquid-liquid critical point for water, likely pre-empted by inevitable freezing. For J=0 the liquid-liquid critical point disappears at T=0.Comment: 8 pages, 4 figure

Manufacturing flow line systems: a review of models and analytical results

The most important models and results of the manufacturing flow line literature are described. These include the major classes of models (asynchronous, synchronous, and continuous); the major features (blocking, processing times, failures and repairs); the major properties (conservation of flow, flow rate-idle time, reversibility, and others); and the relationships among different models. Exact and approximate methods for obtaining quantitative measures of performance are also reviewed. The exact methods are appropriate for small systems. The approximate methods, which are the only means available for large systems, are generally based on decomposition, and make use of the exact methods for small systems. Extensions are briefly discussed. Directions for future research are suggested.National Science Foundation (U.S.) (Grant DDM-8914277