308 research outputs found
Estimation over Communication Networks: Performance Bounds and Achievability Results
This paper considers the problem of estimation over communication networks. Suppose a sensor is taking measurements of a dynamic process. However the process needs to be estimated at a remote location connected to the sensor through a network of communication links that drop packets stochastically. We provide a framework for computing the optimal performance in the sense of expected error covariance. Using this framework we characterize the dependency of the performance on the topology of the network and the packet dropping process. For independent and memoryless packet dropping processes we find the steady-state error for some classes of networks and obtain lower and upper bounds for the performance of a general network. Finally we find a necessary and sufficient condition for the stability of the estimate error covariance for general networks with spatially correlated and Markov type dropping process. This interesting condition has a max-cut interpretation
Lyapunov Conditions for Input-to-State Stability of Impulsive Systems
This paper introduces appropriate concepts of input-to-state stability (ISS) and integral-ISS for impulsive systems, i.e., dynamical systems that evolve according to ordinary differential equations most of the time, but occasionally exhibit discontinuities (or impulses). We provide a set of Lyapunov-based sufficient conditions for establishing these ISS properties. When the continuous dynamics are ISS but the discrete dynamics that govern the impulses are not, the impulses should not occur too frequently, which is formalized in terms of an average dwell-time (ADT) condition. Conversely, when the impulse dynamics are ISS but the continuous dynamics are not, there must not be overly long intervals between impulses, which is formalized in terms of a novel reverse ADT condition. We also investigate the cases where (i) both the continuous and discrete dynamics are ISS and (ii) one of these is ISS and the other only marginally stable for the zero input, while sharing a common Lyapunov function. In the former case we obtain a stronger notion of ISS, for which a necessary and sufficient Lyapunov characterization is available. The use of the tools developed herein is illustrated through examples from a Micro-Electro-Mechanical System (MEMS) oscillator and a problem of remote estimation over a communication network
The Impact of Message Passing in Agent-Based Submodular Maximization
Submodular maximization problems are a relevant model set for many real-world
applications. Since these problems are generally NP-Hard, many methods have
been developed to approximate the optimal solution in polynomial time. One such
approach uses an agent-based greedy algorithm, where the goal is for each agent
to choose an action from its action set such that the union of all actions
chosen is as high-valued as possible. Recent work has shown how the performance
of the greedy algorithm degrades as the amount of information shared among the
agents decreases, whereas this work addresses the scenario where agents are
capable of sharing more information than allowed in the greedy algorithm.
Specifically, we show how performance guarantees increase as agents are capable
of passing messages, which can augment the allowable decision set for each
agent. Under these circumstances, we show a near-optimal method for message
passing, and how much such an algorithm could increase performance for any
given problem instance
Group Chase and Escape
We describe here a new concept of one group chasing another, called "group
chase and escape", by presenting a simple model. We will show that even a
simple model can demonstrate rather rich and complex behavior. In particular,
there are cases in which an optimal number of chasers exists for a given number
of escapees (or targets) to minimize the cost of catching all targets. We have
also found an indication of self-organized spatial structures formed by both
groups.Comment: 13 pages, 12 figures, accepted and to appear in New Journal of
Physic
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