34 research outputs found
An asymptotically optimal model for isotropic heterogeneous linearly elastic plates
In this paper, we derive and analyze a Reissner-Mindlin-like model
for isotropic heterogeneous linearly elastic plates.
The modeling procedure is based on a Hellinger-Reissner principle,
which we modify to derive consistent models.
Due to the material heterogeneity, the classical polynomial profiles
for the plate shear stress are replaced by more sophisticated choices,
that are asymptotically correct.
In the homogeneous case we recover a Reissner-Mindlin model
with 5/6 as shear correction factor.
Asymptotic expansions are used to estimate the modeling error. We remark that our derivation is not based on asymptotic
arguments only.
Thus, the model obtained is more sophisticated (and accurate) than
simply taking the asymptotic limit of the three dimensional problem.
Moreover, we do not assume periodicity of the heterogeneities
Final-state, Open-loop Control of the Heat equation in Tensorial Domains (full version)
In this paper, a quadratic optimal control problem will be considered for the
heat equation in tensorial domains with homogeneous Dirichlet boundary
conditions, in which the control function (depending only on time) constitutes
a source term. These problems involve choosing a control function (with or
without "peak-value" constraints) to approximately steer the solution of the
heat equation to a desired function at the end of a prescribed (finite)
time-interval. To compute approximations to the desired optimal control
functions, semi-discrete, spectral (with eigenfunctions) Galerkin
approximations to the corresponding heat equation and the corresponding
(approximating) control problems are tackled. Two simple, illustrative examples
are presented in the final section.Comment: 32 pages, 11 figures, submitte
Operations and control of unmanned underwater vehicles
Operations and control of unmanned underwater vehicle systems arediscussed in terms of systems and technologies, vehicles, operational deploymentsand concepts of operation. The notions underlying the specification of single vehicleoperations are contrasted to new concepts of operation to illustrate the challengesthey pose to control engineering. New research directions are discussed in thecontext of the theories and techniques from dynamic optimization and computerscience. The overall discussion is done in the context of the activities of theUnderwater Systems and Technology Laboratory from Porto University