41,100 research outputs found
Step-Indexed Logical Relations for Probability (long version)
It is well-known that constructing models of higher-order probabilistic
programming languages is challenging. We show how to construct step-indexed
logical relations for a probabilistic extension of a higher-order programming
language with impredicative polymorphism and recursive types. We show that the
resulting logical relation is sound and complete with respect to the contextual
preorder and, moreover, that it is convenient for reasoning about concrete
program equivalences. Finally, we extend the language with dynamically
allocated first-order references and show how to extend the logical relation to
this language. We show that the resulting relation remains useful for reasoning
about examples involving both state and probabilistic choice.Comment: Extended version with appendix of a FoSSaCS'15 pape
Design and implementation of 30kW 200/900V LCL modular multilevel based DC/DC converter for high power applications
This paper presents the design, development and testing of a 30kW, 200V/900V modular multilevel converter (MMC) based DC/DC converter prototype. An internal LCL circuit is used to provide voltage stepping and fault tolerance property. The converter comprises two five level MMC based on insulated gate bipolar transistors (IGBTs) and metal oxide semiconductor field effect transistor (MOSFET). Due to low number of levels, selective harmonic elimination modulation (SHE) is used, which determines the switching angles in such a way that third harmonic is minimized whereas the fundamental component is a linear function of the modulation index. In addition, instead of using an expensive control board, three commercial control boards are embedded. This is required to implement the sophisticated DC/DC converter control algorithm. Simulation and experimental results are presented to demonstrate the converter performance in step up and down modes
Coherent States for Generalized Laguerre Functions
We explicitly construct a Hamiltonian whose exact eigenfunctions are the
generalized Laguerre functions. Moreover, we present the related raising and
lowering operators. We investigate the corresponding coherent states by
adopting the Gazeau-Klauder approach, where resolution of unity and overlapping
properties are examined. Coherent states are found to be similar to those found
for a particle trapped in a P\"oschl-Teller potential of the trigonometric
type. Some comparisons with Barut-Girardello and Klauder-Perelomov methods are
noticed.Comment: 12 pages, clarifications and references added, misprints correcte
VoroCrust: Voronoi Meshing Without Clipping
Polyhedral meshes are increasingly becoming an attractive option with
particular advantages over traditional meshes for certain applications. What
has been missing is a robust polyhedral meshing algorithm that can handle broad
classes of domains exhibiting arbitrarily curved boundaries and sharp features.
In addition, the power of primal-dual mesh pairs, exemplified by
Voronoi-Delaunay meshes, has been recognized as an important ingredient in
numerous formulations. The VoroCrust algorithm is the first provably-correct
algorithm for conforming polyhedral Voronoi meshing for non-convex and
non-manifold domains with guarantees on the quality of both surface and volume
elements. A robust refinement process estimates a suitable sizing field that
enables the careful placement of Voronoi seeds across the surface circumventing
the need for clipping and avoiding its many drawbacks. The algorithm has the
flexibility of filling the interior by either structured or random samples,
while preserving all sharp features in the output mesh. We demonstrate the
capabilities of the algorithm on a variety of models and compare against
state-of-the-art polyhedral meshing methods based on clipped Voronoi cells
establishing the clear advantage of VoroCrust output.Comment: 18 pages (including appendix), 18 figures. Version without compressed
images available on https://www.dropbox.com/s/qc6sot1gaujundy/VoroCrust.pdf.
Supplemental materials available on
https://www.dropbox.com/s/6p72h1e2ivw6kj3/VoroCrust_supplemental_materials.pd
Thermodynamical Properties of Hall Systems
We study quantum Hall effect within the framework of a newly proposed
approach, which captures the principal results of some proposals. This can be
established by considering a system of particles living on the non-commutative
plane in the presence of an electromagnetic field and quantum statistical
mechanically investigate its basic features. Solving the eigenvalue equation,
we analytically derive the energy levels and the corresponding wavefunctions.
These will be used, at low temperature and weak electric field, to determine
the thermodynamical potential \Omega^{nc} and related physical quantities.
Varying \Omega^{nc} with respect to the non-commutativity parameter \theta, we
define a new function that can be interpreted as a \Omega^{nc} density.
Evaluating the particle number, we show that the Hall conductivity of the
system is \theta-dependent. This allows us to make contact with quantum Hall
effect by offering different interpretations. We study the high temperature
regime and discuss the magnetism of the system. We finally show that at
\theta=2l_B^2, the system is sharing some common features with the Laughlin
theory.Comment: 20 pages, misprints correcte
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