83,667 research outputs found
Issues in the design of switched linear systems : a benchmark study
In this paper we present a tutorial overview of some of the issues that arise in the design of switched linear control systems. Particular emphasis is given to issues relating to stability and control system realisation. A benchmark regulation problem is then presented. This problem is most naturally solved by means of a switched control design. The challenge to the community is to design a control system that meets the required performance specifications and permits the application of rigorous analysis techniques. A simple design solution is presented and the limitations of currently available analysis techniques are illustrated with reference to this example
PMU-Based Estimation of Dynamic State Jacobian Matrix
In this paper, a hybrid measurement- and model-based method is proposed which
can estimate the dynamic state Jacobian matrix in near real-time. The proposed
method is computationally efficient and robust to the variation of network
topology. A numerical example is given to show that the proposed method is able
to provide good estimation for the dynamic state Jacobian matrix and is
superior to the model-based method under undetectable network topology change.
The proposed method may also help identify big discrepancy in the assumed
network model.Comment: IEEE International Conference on Circuits and Systems (ISCAS) 201
Pathogen evolution in switching environments: a hybrid dynamical system approach
We propose a hybrid dynamical system approach to model the evolution of a
pathogen that experiences different selective pressures according to a
stochastic process. In every environment, the evolution of the pathogen is
described by a version of the Fisher-Haldane-Wright equation while the
switching between environments follows a Markov jump process. We investigate
how the qualitative behavior of a simple single-host deterministic system
changes when the stochastic switching process is added. In particular, we study
the stability in probability of monomorphic equilibria. We prove that in a
"constantly" fluctuating environment, the genotype with the highest mean
fitness is asymptotically stable in probability. However, if the probability of
host switching depends on the genotype composition of the population,
polymorphism can be stably maintained.
This is a corrected version of the paper that appeared in Mathematical
Biosciences 240 (2012), p. 70-75. A corrigendum has appeared in the same
journal.Comment: 15 pages, 4 figure
Enhancement of synchronization in a hybrid neural circuit by spike timing dependent plasticity
Synchronization of neural activity is fundamental for many functions of the brain. We demonstrate that spike-timing dependent plasticity (STDP) enhances synchronization (entrainment) in a hybrid circuit composed of a spike generator, a dynamic clamp emulating an excitatory plastic synapse, and a chemically isolated neuron from the Aplysia abdominal ganglion. Fixed-phase entrainment of the Aplysia neuron to the spike generator is possible for a much wider range of frequency ratios and is more precise and more robust with the plastic synapse than with a nonplastic synapse of comparable strength. Further analysis in a computational model of HodgkinHuxley-type neurons reveals the mechanism behind this significant enhancement in synchronization. The experimentally observed STDP plasticity curve appears to be designed to adjust synaptic strength to a value suitable for stable entrainment of the postsynaptic neuron. One functional role of STDP might therefore be to facilitate synchronization or entrainment of nonidentical neurons
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