Network-Enabled Missile Deflection: Games and Correlation Equilibrium

The problem of deploying countermeasures (CM) against antiship missiles is investigated from a network centric perspective in which multiple ships coordinate to defend against a known missile threat. Using the paradigm of network enabled operations (NEOPS), the problem is formulated as a transient stochastic game with communication where the appropriate strategy takes the form of an optimal stationary correlated equilibrium. Under this strategy, ships cooperate through real-time communication to satisfy both local and collective interests. The use of communication results in a performance improvement over the noncommunicating, Nash equilibrium scenario. This framework allows us to develop a theoretical foundation for NEOPS and captures the trade-off between information exchange and performance, while generalizing the standard Nash equilibrium solution for the missile deflection game given in [1], The NEOPS equilibrium strategy is characterized as the solution to an optimization problem with linear objective and bilinear constraints, which can be solved calculating successive improvements starting from an initial noncooperative (Nash) solution. The communication overhead required to implement this strategy is associated with the mutual information between individual action probability distributions at equilibrium. Numerical results illustrate the trade-off between communication and performance.     

Asynchronous Performance of Polyphase Slitted Rotor Reluctance Machine

The asynchronous performance of a polyphase reluctance machine with rotor provided with axial slits is investigated for the first time on the basis of conductor boundary treated as a flux line. Theoretical and experimental investigations are presented for rotors with 1) many values of pole arc/pole pitch ratio, 2) varying slot depths, 3) slots on either pole faces or slot portions or both of them, and 4) with and without terminating end rings. Their comparison with predictions leads to interesting conclusions.     

Cochannel Interference in Partially Coherent Communication

Effects of cochannel interference and synchronization error of the carrier phase on the probability of error in binary communications are considered. Several bounds on the probability of error are proposed. The bounds are easy to compute and do not require complete statistical characterization of the errors. They turn out to be simple linear combinations of error probabilities with no cochannel interferences and no phase errors. Several illustrative examples are given which show that the bounds can be tight.     

Reduced spatio-temporal complexity MMPP and image-based tracking filters for maneuvering targets

We present reduced-complexity nonlinear filtering algorithms for image-based tracking of maneuvering targets. In image-based target tracking, the mode of the target is observed as a Markov modulated Poisson process (MMPP) and the aim is to compute optimal estimates of the target's state. We present a reduced complexity algorithm in two steps. First, a gauge transformation is used to reexpress the filtering equations in a form that is computationally more efficient for time discretization than naive discretization of the filtering equations. Second, a spatial aggregation algorithm with guaranteed performance bounds is presented for the time-discretized filters. A numerical example illustrating the performance of the resulting reduced-complexity filtering algorithms for a switching turn-rate model is presented.     

Asynchronous Performance of Slitted Rotor Reluctance Machines: Saturation Effects

Analytical investigation based on limiting nonlinear theory presented here for the asychronous performance of a slitted solid iron rotor reluctance machine include the effect of rotor iron saturation. Characteristic curves depicting nondimensional expressions developed for the rotor impedance factor and the power factor enable a visualization of the effects of 1) ratio of depth of saliency to depth of penetration, 2) slit number and depth, and 3) effective resistivities and saturation flux densities of different regions of the rotor on rotor parameter variations. Further predicted values are compared with experimental values and conclusions are drawn.     

Performance analysis of a dynamic programming track before detectalgorithm

We analyze a dynamic programming (DP)-based track before detect (TBD) algorithm. By using extreme value theory we obtain explicit expressions for various performance measures of the algorithm such as probability of detection and false alarm. Our analysis has two advantages. First the unrealistic Gaussian and independence assumptions used in previous works are not required. Second, the probability of detection and false alarm curves obtained fit computer simulated performance results significantly more accurately than previously proposed analyses of the TBD algorithm     

Hierarchical resource management in adaptive airborne surveillance radars

In this paper we present hierarchical resource management algorithms for adaptive airborne surveillance radars. By abstracting the physical layer sensor performance into a quality of service measure, the resource management problem is formulated as a constrained Markov decision process. A two-level (two-timescale) resource management algorithm is presented based on Lagrangian relaxation. A numerical example is given with scenarios involving different target densities.     

Emission management for low probability intercept sensors in network centric warfare

Sensor platforms with active sensing equipment such as radars may betray their existence, by emitting energy that can be intercepted by enemy surveillance sensors thereby increasing the vulnerability of the whole combat system. To achieve the important tactical requirement of low probability of intercept (LPI) requires dynamically controlling the emission of platforms. In this paper we propose computationally efficient dynamic emission control and management algorithms for multiple networked heterogenous platforms. By formulating the problem as a partially observed Markov decision process (POMDP) with an on-going multi-armed bandit structure, near optimal sensor management algorithms are developed for controlling the active sensor emission to minimize the threat posed to all the platforms. Numerical examples are presented to illustrate these control/management algorithms.     

On gas-phase ignition of diffusion flame in the stagnation-point boundary layer

An analytical expression for gas-phase ignition is developed for a diffusion flame in the two-dimensional or axisymmetric stagnation-point boundary-layer flow of a hot oxidizing gas about a vaporizing condensed fuel surface. The analysis is based on the limit of large activation energy for a one-step, irreversible reaction describing the overall combustion process in the gas phase. The approach in this work, following that of our recent analysis on extinction for the same geometry, is to seek an exact correspondence of the parameters of the present problem with those of counterflow diffusion-flame problem of Liñán. Such a correspondence has been found in the frozen-flow regime and as a consequence, the asymptotic structure of the flame in the nearly frozen ignition regime is identical in both the problems. A particular result of this observation is the availability of an analytical criterion for ignition in the present problem. The analysis reveals that contrary to the case of extinction, fluid dynamic details do not have significant effect on the ignition criterion and that Liñán's results may be applied with good accuracy to the condensed fuel problem.     

Bounds on the Probability of Error in Digitial Communications

A class of upper bounds and lower bounds on the probability of error in digital communications are derived. Several degrading factors like intersymbol interference, cochannel interference, inaccurate carrier synchronization, and incoherent detection can be considered in obtaining the bounds. Several examples are given and it is shown that many situations not considered so far can be put into the conceptual framework developed here.