Search results for "Inuit"

Approximation of piecewise smooth functions and images by edge-adapted (ENO-EA) nonlinear multiresolution techniques

2008

Abstract This paper introduces and analyzes new approximation procedures for bivariate functions. These procedures are based on an edge-adapted nonlinear reconstruction technique which is an intrinsically two-dimensional extension of the essentially non-oscillatory and subcell resolution techniques introduced in the one-dimensional setting by Harten and Osher. Edge-adapted reconstructions are tailored to piecewise smooth functions with geometrically smooth edge discontinuities, and are therefore attractive for applications such as image compression and shock computations. The local approximation order is investigated both in L p and in the Hausdorff distance between graphs. In particular, i…

On a new centered strategy to control the accuracy of weighted essentially non oscillatory algorithm for conservation laws close to discontinuities

2020

Efficient boundary integral-resonant mode expansion method implementation for full-wave analysis of passive devices based on circular waveguides with…

2013

In this study, the efficient full-wave analysis of passive devices composed of circular and arbitrarily-shaped waveguides is considered. For this purpose, the well-known boundary integral-resonant mode expansion (BI RME) method has been properly extended. Circular waveguides are used for resonant mode expansion, whereas the arbitrary contour is defined by any combination of straight, circular and elliptical segments, thus allowing the exact representation of the most widely used geometries. The proposed algorithm extends previous implementations of the BI RME method based on circular waveguides by considering circular and elliptical arcs for defining arbitrary geometries. Similarly, it allo…

Local regularity for time-dependent tug-of-war games with varying probabilities

2016

We study local regularity properties of value functions of time-dependent tug-of-war games. For games with constant probabilities we get local Lipschitz continuity. For more general games with probabilities depending on space and time we obtain H\"older and Harnack estimates. The games have a connection to the normalized $p(x,t)$-parabolic equation $(n+p(x,t))u_t=\Delta u+(p(x,t)-2) \Delta_{\infty}^N u$.

Fake Nodes approximation for Magnetic Particle Imaging

2020

Accurately reconstructing functions with discontinuities is the key tool in many bio-imaging applications as, for instance, in Magnetic Particle Imaging (MPI). In this paper, we apply a method for scattered data interpolation, named mapped bases or Fake Nodes approach, which incorporates discontinuities via a suitable mapping function. This technique naturally mitigates the Gibbs phenomenon, as numerical evidence for reconstructing MPI images confirms.

On the application of the generalized means to construct multiresolution schemes satisfying certain inequalities proving stability

2021

Multiresolution representations of data are known to be powerful tools in data analysis and processing, and they are particularly interesting for data compression. In order to obtain a proper definition of the edges, a good option is to use nonlinear reconstructions. These nonlinear reconstruction are the heart of the prediction processes which appear in the definition of the nonlinear subdivision and multiresolution schemes. We define and study some nonlinear reconstructions based on the use of nonlinear means, more in concrete the so-called Generalized means. These means have two interesting properties that will allow us to get associated reconstruction operators adapted to the presence o…

Faults identification, location and characterization in electrical systems using an analytical model-based approach

2005

The start of the electrical energy market has encouraged distributors to make new investments at distribution level so as to attain higher quality levels. The service continuity is one of the aspects of greater importance in the definition of the quality of the electrical energy. For this reason, the research in the field of fault diagnostic for distribution systems is spreading ever more. This paper presents a novel methodology to identify, locate and characterize the faulty events in the electrical distribution systems. The methodology can be extended to all types of faulty events and is applicable to reconfigurable systems. After having described the guidelines of the methodology, the Au…

Does Regression Discontinuity Design Work? Evidence from Random Election Outcomes

2014

We use data for 198121 candidates and 1351 random election outcomes to estimate the effect of incumbency status on future electoral success. We find no evidence of incumbency advantage using data on randomized elections. In contrast, regression discontinuity design, using optimal bandwidths, produces a positive and significant incumbency effect. Using even narrower bandwidths aligns the results with those obtained using the randomized elections. So does the bias-correction of Calonico et al. (forthcoming). Standard validity tests are not useful in detecting the problems with the optimal bandwidths. The appropriate bandwidth seems narrower in larger elections and is thus context specific.

Fine-Mesh Numerical Simulations for 2D Riemann Problems with a Multilevel Scheme

2001

The numerical simulation of physical problems modeled by systems of conservation laws can be difficult due to the occurrence of discontinuities and other non-smooth features in the solution.

Partial self-consistency and analyticity in many-body perturbation theory: Particle number conservation and a generalized sum rule

2016

We consider a general class of approximations which guarantees the conservation of particle number in many-body perturbation theory. To do this we extend the concept of $\Phi$-derivability for the self-energy $\Sigma$ to a larger class of diagrammatic terms in which only some of the Green's function lines contain the fully dressed Green's function $G$. We call the corresponding approximations for $\Sigma$ partially $\Phi$-derivable. A special subclass of such approximations, which are gauge-invariant, is obtained by dressing loops in the diagrammatic expansion of $\Phi$ consistently with $G$. These approximations are number conserving but do not have to fulfill other conservation laws, such…