839 research outputs found
Interior feedback stabilization of wave equations with dynamic boundary delay
In this paper we consider an interior stabilization problem for the wave
equation with dynamic boundary delay.We prove some stability results under the
choice of damping operator. The proof of the main result is based on a
frequency domain method and combines a contradiction argument with the
multiplier technique to carry out a special analysis for the resolvent
Filtering for distributed mechanical systems using position measurements: perspectives in medical imaging
International audienceWe propose an effective filtering methodology designed to perform estimation in a distributed mechanical system using position measurements. As in a previously introduced method, the filter is inspired from robust control feedback, but here we take full advantage of the estimation specificity to choose a feedback law that can act on displacements instead of velocities and still retain the same kind of dissipativity property which guarantees robustness. This is very valuable in many applications for which positions are more readily available than velocities, as in medical imaging. We provide an in-depth analysis of the proposed procedure, as well as detailed numerical assessments using a test problem inspired from cardiac biomechanics, as medical diagnosis assistance is an important perspective for this approach. The method is formulated first for measurements based on Lagrangian displacements, but we then derive a nonlinear extension allowing to instead consider segmented images, which of course is even more relevant in medical applications
MIT Space Engineering Research Center
The Space Engineering Research Center (SERC) at MIT, started in Jul. 1988, has completed two years of research. The Center is approaching the operational phase of its first testbed, is midway through the construction of a second testbed, and is in the design phase of a third. We presently have seven participating faculty, four participating staff members, ten graduate students, and numerous undergraduates. This report reviews the testbed programs, individual graduate research, other SERC activities not funded by the Center, interaction with non-MIT organizations, and SERC milestones. Published papers made possible by SERC funding are included at the end of the report
Observers for compressible Navier-Stokes equation
We consider a multi-dimensional model of a compressible fluid in a bounded
domain. We want to estimate the density and velocity of the fluid, based on the
observations for only velocity. We build an observer exploiting the symmetries
of the fluid dynamics laws. Our main result is that for the linearised system
with full observations of the velocity field, we can find an observer which
converges to the true state of the system at any desired convergence rate for
finitely many but arbitrarily large number of Fourier modes. Our
one-dimensional numerical results corroborate the results for the linearised,
fully observed system, and also show similar convergence for the full nonlinear
system and also for the case when the velocity field is observed only over a
subdomain
Minimum time control of heterodirectional linear coupled hyperbolic PDEs
We solve the problem of stabilization of a class of linear first-order
hyperbolic systems featuring n rightward convecting transport PDEs and m
leftward convecting transport PDEs. Using the backstepping approach yields
solutions to stabilization in minimal time and observer based output feedback
On Polynomial Stability of Coupled Partial Differential Equations in 1D
We study the well-posedness and asymptotic behaviour of selected PDE-PDE and
PDE-ODE systems on one-dimensional spatial domains, namely a boundary coupled
wave-heat system and a wave equation with a dynamic boundary condition. We
prove well-posedness of the models and derive rational decay rates for the
energy using an approach where the coupled systems are formulated as feedback
interconnections of impedance passive regular linear systems.Comment: 12 pages, 1 figure, accepted for publication in the Proceedings of
"Semigroups of Operators: Theory and Applications", Kazimierz Dolny, Poland,
October 201
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