6,785 research outputs found
Hypercube matrix computation task
A major objective of the Hypercube Matrix Computation effort at the Jet Propulsion Laboratory (JPL) is to investigate the applicability of a parallel computing architecture to the solution of large-scale electromagnetic scattering problems. Three scattering analysis codes are being implemented and assessed on a JPL/California Institute of Technology (Caltech) Mark 3 Hypercube. The codes, which utilize different underlying algorithms, give a means of evaluating the general applicability of this parallel architecture. The three analysis codes being implemented are a frequency domain method of moments code, a time domain finite difference code, and a frequency domain finite elements code. These analysis capabilities are being integrated into an electromagnetics interactive analysis workstation which can serve as a design tool for the construction of antennas and other radiating or scattering structures. The first two years of work on the Hypercube Matrix Computation effort is summarized. It includes both new developments and results as well as work previously reported in the Hypercube Matrix Computation Task: Final Report for 1986 to 1987 (JPL Publication 87-18)
Multi-Objective Model Checking of Markov Decision Processes
We study and provide efficient algorithms for multi-objective model checking
problems for Markov Decision Processes (MDPs). Given an MDP, M, and given
multiple linear-time (\omega -regular or LTL) properties \varphi\_i, and
probabilities r\_i \epsilon [0,1], i=1,...,k, we ask whether there exists a
strategy \sigma for the controller such that, for all i, the probability that a
trajectory of M controlled by \sigma satisfies \varphi\_i is at least r\_i. We
provide an algorithm that decides whether there exists such a strategy and if
so produces it, and which runs in time polynomial in the size of the MDP. Such
a strategy may require the use of both randomization and memory. We also
consider more general multi-objective \omega -regular queries, which we
motivate with an application to assume-guarantee compositional reasoning for
probabilistic systems.
Note that there can be trade-offs between different properties: satisfying
property \varphi\_1 with high probability may necessitate satisfying \varphi\_2
with low probability. Viewing this as a multi-objective optimization problem,
we want information about the "trade-off curve" or Pareto curve for maximizing
the probabilities of different properties. We show that one can compute an
approximate Pareto curve with respect to a set of \omega -regular properties in
time polynomial in the size of the MDP.
Our quantitative upper bounds use LP methods. We also study qualitative
multi-objective model checking problems, and we show that these can be analysed
by purely graph-theoretic methods, even though the strategies may still require
both randomization and memory.Comment: 21 pages, 2 figure
A taxonomy framework for unsupervised outlier detection techniques for multi-type data sets
The term "outlier" can generally be defined as an observation that is significantly different from
the other values in a data set. The outliers may be instances of error or indicate events. The
task of outlier detection aims at identifying such outliers in order to improve the analysis of
data and further discover interesting and useful knowledge about unusual events within numerous
applications domains. In this paper, we report on contemporary unsupervised outlier detection
techniques for multiple types of data sets and provide a comprehensive taxonomy framework and
two decision trees to select the most suitable technique based on data set. Furthermore, we
highlight the advantages, disadvantages and performance issues of each class of outlier detection
techniques under this taxonomy framework
FIESTA 2: parallelizeable multiloop numerical calculations
The program FIESTA has been completely rewritten. Now it can be used not only
as a tool to evaluate Feynman integrals numerically, but also to expand Feynman
integrals automatically in limits of momenta and masses with the use of sector
decompositions and Mellin-Barnes representations. Other important improvements
to the code are complete parallelization (even to multiple computers),
high-precision arithmetics (allowing to calculate integrals which were undoable
before), new integrators and Speer sectors as a strategy, the possibility to
evaluate more general parametric integrals.Comment: 31 pages, 5 figure
Dynamics of iterative families with memory based on weight functions procedure
[EN] In this paper, we analyze the stability of a parametric family of iterative methods with memory for solving nonlinear equations. This family is obtained from an optimal class of fourth -order schemes without memory designed by means of weight functions procedure. By studying the real fixed and critical points of the rational function resulting from the application of the family with memory on quadratic polynomials, the best elements of the family, in terms of absence of chaotic behavior, are selected. Finally, a numerical study is performed verifying the dynamical theoretical results. (C) 2018 Elsevier B.V. All rights reserved.The authors would like to thank the anonymous reviewers for their useful comments and suggestions. This research was partially supported by both Ministerio de Economia y Competitividad and Generalitat Valenciana, Spain, under grants MTM2014-52016-C2-2-P and PROMETE0/2016/089, respectively.Chicharro López, FI.; Cordero Barbero, A.; Torregrosa Sánchez, JR. (2019). Dynamics of iterative families with memory based on weight functions procedure. Journal of Computational and Applied Mathematics. 354:286-298. https://doi.org/10.1016/j.cam.2018.01.019S28629835
Geodesics on an ellipsoid of revolution
Algorithms for the computation of the forward and inverse geodesic problems
for an ellipsoid of revolution are derived. These are accurate to better than
15 nm when applied to the terrestrial ellipsoids. The solutions of other
problems involving geodesics (triangulation, projections, maritime boundaries,
and polygonal areas) are investigated.Comment: LaTex, 29 pages, 16 figures. Supplementary material is available at
http://geographiclib.sourceforge.net/geod.htm
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