54,831 research outputs found
ENO-wavelet transforms for piecewise smooth functions
We have designed an adaptive essentially nonoscillatory (ENO)-wavelet transform for approximating discontinuous functions without oscillations near the discontinuities. Our approach is to apply the main idea from ENO schemes for numerical shock capturing to standard wavelet transforms. The crucial point is that the wavelet coefficients are computed without differencing function values across jumps. However, we accomplish this in a different way than in the standard ENO schemes. Whereas in the standard ENO schemes the stencils are adaptively chosen, in the ENO-wavelet transforms we adaptively change the function and use the same uniform stencils. The ENO-wavelet transform retains the essential properties and advantages of standard wavelet transforms such as concentrating the energy to the low frequencies, obtaining maximum accuracy, maintained up to the discontinuities, and having a multiresolution framework and fast algorithms, all without any edge artifacts. We have obtained a rigorous approximation error bound which shows that the error in the ENO-wavelet approximation depends only on the size of the derivative of the function away from the discontinuities. We will show some numerical examples to illustrate this error estimate
Four functions of mens rea
Everyone agrees that mens rea is relevant to fault. The maxim actus non fit reus nisi mens sit rea has been around for centuries.1 According to foundational principles of the criminal law, it is normally not enough to support a conviction that D perpetrates the actus reus. Neither should it be. Causing harm to another person may be unfortunate, but the moral turpitude associated with a criminal conviction requires some element of fault. And to show that, we need mens rea
Inducing breach of contract: one tort or two?
IT is said to be a tort for D intentionally to induce C to break C’s contract with P. Where this occurs, P has an action in tort against D, quite apart from P’s action for breach of contract against C. But the rationale for this tort is controversial, and its legitimacy has been doubted by a number of commentators
Computer evaluation of network performance by a topological flowgraph technique
Algorithm for computer evaluation of linear network by topological flow techniqu
Gravastars and Black Holes of Anisotropic Dark Energy
Dynamical models of prototype gravastars made of anisotropic dark energy are
constructed, in which an infinitely thin spherical shell of a perfect fluid
with the equation of state divides the whole spacetime
into two regions, the internal region filled with a dark energy fluid, and the
external Schwarzschild region. The models represent "bounded excursion" stable
gravastars, where the thin shell is oscillating between two finite radii, while
in other cases they collapse until the formation of black holes. Here we show,
for the first time in the literature, a model of gravastar and formation of
black hole with both interior and thin shell constituted exclusively of dark
energy. Besides, the sign of the parameter of anisotropy () seems to
be relevant to the gravastar formation. The formation is favored when the
tangential pressure is greater than the radial pressure, at least in the
neighborhood of the isotropic case ().Comment: 16 pages, 8 figures. Accepted for publication in Gen. Rel. Gra
LDPC Code Design for the BPSK-constrained Gaussian Wiretap Channel
A coding scheme based on irregular low-density parity-check (LDPC) codes is
proposed to send secret messages from a source over the Gaussian wiretap
channel to a destination in the presence of a wiretapper, with the restriction
that the source can send only binary phase-shift keyed (BPSK) symbols. The
secrecy performance of the proposed coding scheme is measured by the secret
message rate through the wiretap channel as well as the equivocation rate about
the message at the wiretapper. A code search procedure is suggested to obtain
irregular LDPC codes that achieve good secrecy performance in such context.Comment: submitted to IEEE GLOBECOM 2011 - Communication Theory Symposiu
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