3,377 research outputs found
Penny-shaped crack in a fiber-reinforced matrix
Using a slender inclusion model developed earlier, the elastostatic interaction problem between a penny-shaped crack and elastic fibers in an elastic matrix is formulated. For a single set and for multiple sets of fibers oriented perpendicularly to the plane of the crack and distributed symmetrically on concentric circles, the problem was reduced to a system of singular integral equations. Techniques for the regularization and for the numerical solution of the system are outlined. For various fiber geometries numerical examples are given, and distribution of the stress intensity factor along the crack border was obtained. Sample results showing the distribution of the fiber stress and a measure of the fiber-matrix interface shear are also included
On linear H∞ equalization of communication channels
As an alternative to existing techniques and algorithms, we investigate the merit of the H∞ approach to the linear equalization of communication channels. We first give the formulation of all causal H∞ equalizers using the results of and then look at the finite delay case. We compare the risk-sensitive H∞ equalizer with the MMSE equalizer with respect to both the average and the worst-case BER performances and illustrate the improvement due to the use of the H∞ equalizer
Spontaneous decay of an excited atom placed near a rectangular plate
Using the Born expansion of the Green tensor, we consider the spontaneous
decay rate of an excited atom placed in the vicinity of a rectangular plate. We
discuss the limitations of the commonly used simplifying assumption that the
plate extends to infinity in the lateral directions and examine the effects of
the atomic dipole moment orientation, atomic position, and plate boundary and
thickness on the atomic decay rate. In particular, it is shown that in the
boundary region, the spontaneous decay rate can be strongly modified.Comment: 5 pages, 5 figure
A Bayesian Perspective for Determinant Minimization Based Robust Structured Matrix Factorizatio
We introduce a Bayesian perspective for the structured matrix factorization
problem. The proposed framework provides a probabilistic interpretation for
existing geometric methods based on determinant minimization. We model input
data vectors as linear transformations of latent vectors drawn from a
distribution uniform over a particular domain reflecting structural
assumptions, such as the probability simplex in Nonnegative Matrix
Factorization and polytopes in Polytopic Matrix Factorization. We represent the
rows of the linear transformation matrix as vectors generated independently
from a normal distribution whose covariance matrix is inverse Wishart
distributed. We show that the corresponding maximum a posteriori estimation
problem boils down to the robust determinant minimization approach for
structured matrix factorization, providing insights about parameter selections
and potential algorithmic extensions
Qualitative features of periodic solutions of KdV
In this paper we prove new qualitative features of solutions of KdV on the
circle. The first result says that the Fourier coefficients of a solution of
KdV in Sobolev space , admit a WKB type expansion up to first
order with strongly oscillating phase factors defined in terms of the KdV
frequencies. The second result provides estimates for the approximation of such
a solution by trigonometric polynomials of sufficiently large degree
An energy-based material model for the simulation of shape memory alloys under complex boundary value problems
Shape memory alloys are remarkable 'smart' materials used in a broad spectrum
of applications, ranging from aerospace to robotics, thanks to their unique
thermomechanical coupling capabilities. Given the complex properties of shape
memory alloys, which are largely influenced by thermal and mechanical loads, as
well as their loading history, predicting their behavior can be challenging.
Consequently, there exists a pronounced demand for an efficient material model
to simulate the behavior of these alloys. This paper introduces a material
model rooted in Hamilton's principle. The key advantages of the presented
material model encompass a more accurate depiction of the internal variable
evolution and heightened robustness. As such, the proposed material model
signifies an advancement in the realistic and efficient simulation of shape
memory alloys
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